Muscarinic ACh Receptors Contribute to Aversive Olfactory Learning in Drosophila

PubMed Central

Silva, Bryon; Molina-Fernández, Claudia; Ugalde, María Beatriz; Tognarelli, Eduardo I.; Angel, Cristian; Campusano, Jorge M.

2015-01-01

The most studied form of associative learning in Drosophila consists in pairing an odorant, the conditioned stimulus (CS), with an unconditioned stimulus (US). The timely arrival of the CS and US information to a specific Drosophila brain association region, the mushroom bodies (MB), can induce new olfactory memories. Thus, the MB is considered a coincidence detector. It has been shown that olfactory information is conveyed to the MB through cholinergic inputs that activate acetylcholine (ACh) receptors, while the US is encoded by biogenic amine (BA) systems. In recent years, we have advanced our understanding on the specific neural BA pathways and receptors involved in olfactory learning and memory. However, little information exists on the contribution of cholinergic receptors to this process. Here we evaluate for the first time the proposition that, as in mammals, muscarinic ACh receptors (mAChRs) contribute to memory formation in Drosophila. Our results show that pharmacological and genetic blockade of mAChRs in MB disrupts olfactory aversive memory in larvae. This effect is not explained by an alteration in the ability of animals to respond to odorants or to execute motor programs. These results show that mAChRs in MB contribute to generating olfactory memories in Drosophila. PMID:26380118

Food Avoidance Learning in Squirrel Monkeys and Common Marmosets

PubMed Central

Laska, Matthias; Metzker, Karin

1998-01-01

Using a conditioned food avoidance learning paradigm, six squirrel monkeys (Saimiri sciureus) and six common marmosets (Callithrix jacchus) were tested for their ability to (1) reliably form associations between visual or olfactory cues of a potential food and its palatability and (2) remember such associations over prolonged periods of time. We found (1) that at the group level both species showed one-trial learning with the visual cues color and shape, whereas only the marmosets were able to do so with the olfactory cue, (2) that all individuals from both species learned to reliably avoid the unpalatable food items within 10 trials, (3) a tendency in both species for quicker acquisition of the association with the visual cues compared with the olfactory cue, (4) a tendency for quicker acquisition and higher reliability of the aversion by the marmosets compared with the squirrel monkeys, and (5) that all individuals from both species were able to reliably remember the significance of the visual cues, color and shape, even after 4 months, whereas only the marmosets showed retention of the significance of the olfactory cues for up to 4 weeks. Furthermore, the results suggest that in both species tested, illness is not a necessary prerequisite for food avoidance learning but that the presumably innate rejection responses toward highly concentrated but nontoxic bitter and sour tastants are sufficient to induce robust learning and retention. PMID:10454364

A distinct entorhinal cortex to hippocampal CA1 direct circuit for olfactory associative learning.

PubMed

Li, Yiding; Xu, Jiamin; Liu, Yafeng; Zhu, Jia; Liu, Nan; Zeng, Wenbo; Huang, Ning; Rasch, Malte J; Jiang, Haifei; Gu, Xiang; Li, Xiang; Luo, Minhua; Li, Chengyu; Teng, Junlin; Chen, Jianguo; Zeng, Shaoqun; Lin, Longnian; Zhang, Xiaohui

2017-04-01

Lateral and medial parts of entorhinal cortex (EC) convey nonspatial 'what' and spatial 'where' information, respectively, into hippocampal CA1, via both the indirect EC layer 2→ hippocampal dentate gyrus→CA3→CA1 and the direct EC layer 3→CA1 paths. However, it remains elusive how the direct path transfers distinct information and contributes to hippocampal learning functions. Here we report that lateral EC projection neurons selectively form direct excitatory synapses onto a subpopulation of morphologically complex, calbindin-expressing pyramidal cells (PCs) in the dorsal CA1 (dCA1), while medial EC neurons uniformly innervate all dCA1 PCs. Optogenetically inactivating the distinct lateral EC-dCA1 connections or the postsynaptic dCA1 calbindin-expressing PC activity slows olfactory associative learning. Moreover, optetrode recordings reveal that dCA1 calbindin-expressing PCs develop more selective spiking responses to odor cues during learning. Thus, our results identify a direct lateral EC→dCA1 circuit that is required for olfactory associative learning.

Odor-Induced Neuronal Rhythms in the Olfactory Bulb Are Profoundly Modified in ob/ob Obese Mice

PubMed Central

Chelminski, Yan; Magnan, Christophe; Luquet, Serge H.; Everard, Amandine; Meunier, Nicolas; Gurden, Hirac; Martin, Claire

2017-01-01

Leptin, the product of the Ob(Lep) gene, is a peptide hormone that plays a major role in maintaining the balance between food intake and energy expenditure. In the brain, leptin receptors are expressed by hypothalamic cells but also in the olfactory bulb, the first central structure coding for odors, suggesting a precise function of this hormone in odor-evoked activities. Although olfaction plays a key role in feeding behavior, the ability of the olfactory bulb to integrate the energy-related signal leptin is still missing. Therefore, we studied the fate of odor-induced activity in the olfactory bulb in the genetic context of leptin deficiency using the obese ob/ob mice. By means of an odor discrimination task with concomitant local field potential recordings, we showed that ob/ob mice perform better than wild-type (WT) mice in the early stage of the task. This behavioral gain of function was associated in parallel with profound changes in neuronal oscillations in the olfactory bulb. The distribution of the peaks in the gamma frequency range was shifted toward higher frequencies in ob/ob mice compared to WT mice before learning. More notably, beta oscillatory activity, which has been shown previously to be correlated with olfactory discrimination learning, was longer and stronger in expert ob/ob mice after learning. Since oscillations in the olfactory bulb emerge from mitral to granule cell interactions, our results suggest that cellular dynamics in the olfactory bulb are deeply modified in ob/ob mice in the context of olfactory learning. PMID:28154537

Tunicamycin impairs olfactory learning and synaptic plasticity in the olfactory bulb.

PubMed

Tong, Jia; Okutani, Fumino; Murata, Yoshihiro; Taniguchi, Mutsuo; Namba, Toshiharu; Wang, Yu-Jie; Kaba, Hideto

2017-03-06

Tunicamycin (TM) induces endoplasmic reticulum (ER) stress and inhibits N-glycosylation in cells. ER stress is associated with neuronal death in neurodegenerative disorders, such as Parkinson's disease and Alzheimer's disease, and most patients complain of the impairment of olfactory recognition. Here we examined the effects of TM on aversive olfactory learning and the underlying synaptic plasticity in the main olfactory bulb (MOB). Behavioral experiments demonstrated that the intrabulbar infusion of TM disabled aversive olfactory learning without affecting short-term memory. Histological analyses revealed that TM infusion upregulated C/EBP homologous protein (CHOP), a marker of ER stress, in the mitral and granule cell layers of MOB. Electrophysiological data indicated that TM inhibited tetanus-induced long-term potentiation (LTP) at the dendrodendritic excitatory synapse from mitral to granule cells. A low dose of TM (250nM) abolished the late phase of LTP, and a high dose (1μM) inhibited the early and late phases of LTP. Further, high-dose, but not low-dose, TM reduced the paired-pulse facilitation ratio, suggesting that the inhibitory effects of TM on LTP are partially mediated through the presynaptic machinery. Thus, our results support the hypothesis that TM-induced ER stress impairs olfactory learning by inhibiting synaptic plasticity via presynaptic and postsynaptic mechanisms in MOB. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

A model of olfactory associative learning

NASA Astrophysics Data System (ADS)

Tavoni, Gaia; Balasubramanian, Vijay

We propose a mechanism, rooted in the known anatomy and physiology of the vertebrate olfactory system, by which presentations of rewarded and unrewarded odors lead to formation of odor-valence associations between piriform cortex (PC) and anterior olfactory nucleus (AON) which, in concert with neuromodulators release in the bulb, entrains a direct feedback from the AON representation of valence to a group of mitral cells (MCs). The model makes several predictions concerning MC activity during and after associative learning: (a) AON feedback produces synchronous divergent responses in a localized subset of MCs; (b) such divergence propagates to other MCs by lateral inhibition; (c) after learning, MC responses reconverge; (d) recall of the newly formed associations in the PC increases feedback inhibition in the MCs. These predictions have been confirmed in disparate experiments which we now explain in a unified framework. For cortex, our model further predicts that the response divergence developed during learning reshapes odor representations in the PC, with the effects of (a) decorrelating PC representations of odors with different valences, (b) increasing the size and reliability of those representations, and enabling recall correction and redundancy reduction after learning. Simons Foundation for Mathematical Modeling of Living Systems.

Steroid Hormone (20-Hydroxyecdysone) Modulates the Acquisition of Aversive Olfactory Memories in Pollen Forager Honeybees

ERIC Educational Resources Information Center

Geddes, Lisa H.; McQuillan, H. James; Aiken, Alastair; Vergoz, Vanina; Mercer, Alison R.

2013-01-01

Here, we examine effects of the steroid hormone, 20-hydroxyecdysone (20-E), on associative olfactory learning in the honeybee, "Apis mellifera." 20-E impaired the bees' ability to associate odors with punishment during aversive conditioning, but did not interfere with their ability to associate odors with a food reward (appetitive…

Predicting human olfactory perception from chemical features of odor molecules.

PubMed

Keller, Andreas; Gerkin, Richard C; Guan, Yuanfang; Dhurandhar, Amit; Turu, Gabor; Szalai, Bence; Mainland, Joel D; Ihara, Yusuke; Yu, Chung Wen; Wolfinger, Russ; Vens, Celine; Schietgat, Leander; De Grave, Kurt; Norel, Raquel; Stolovitzky, Gustavo; Cecchi, Guillermo A; Vosshall, Leslie B; Meyer, Pablo

2017-02-24

It is still not possible to predict whether a given molecule will have a perceived odor or what olfactory percept it will produce. We therefore organized the crowd-sourced DREAM Olfaction Prediction Challenge. Using a large olfactory psychophysical data set, teams developed machine-learning algorithms to predict sensory attributes of molecules based on their chemoinformatic features. The resulting models accurately predicted odor intensity and pleasantness and also successfully predicted 8 among 19 rated semantic descriptors ("garlic," "fish," "sweet," "fruit," "burnt," "spices," "flower," and "sour"). Regularized linear models performed nearly as well as random forest-based ones, with a predictive accuracy that closely approaches a key theoretical limit. These models help to predict the perceptual qualities of virtually any molecule with high accuracy and also reverse-engineer the smell of a molecule. Copyright © 2017, American Association for the Advancement of Science.

Effects of Caffeine on Olfactory Learning in Crickets.

PubMed

Sugimachi, Seigo; Matsumoto, Yukihisa; Mizunami, Makoto; Okada, Jiro

2016-10-01

Caffeine is a plant-derived alkaloid that is generally known as a central nervous system (CNS) stimulant. In order to examine the effects of caffeine on higher CNS functions in insects, we used an appetitive olfactory learning paradigm for the cricket Gryllus bimaculatus. Crickets can form significant long-term memories (LTMs) after repetitive training sessions, during which they associate a conditioned stimulus (CS: odor) with an unconditioned stimulus (US: reward). Administration of hemolymphal injections of caffeine established LTM after only single-trial conditioning over a wide range of caffeine dosages (1.6 µµg/kg to 39 mg/kg). We investigated the physiological mechanisms underlying this enhancement of olfactory learning performance pharmacologically, focusing on three major physiological roles of caffeine: 1) inhibition of phosphodiesterase (PDE), 2) agonism of ryanodine receptors, and 3) antagonism of adenosine receptors. Application of drugs relevant to these actions resulted in significant effects on LTM formation. These results suggest that externally applied caffeine enhances LTM formation in insect olfactory learning via multiple cellular mechanisms.

Acetylcholine and Olfactory Perceptual Learning

ERIC Educational Resources Information Center

Wilson, Donald A.; Fletcher, Max L.; Sullivan, Regina M.

2004-01-01

Olfactory perceptual learning is a relatively long-term, learned increase in perceptual acuity, and has been described in both humans and animals. Data from recent electrophysiological studies have indicated that olfactory perceptual learning may be correlated with changes in odorant receptive fields of neurons in the olfactory bulb and piriform…

Olfactory learning prevents MK-801-induced psychosis-like behaviour in an animal model of schizophrenia.

PubMed

Naimark, Ari; Barkai, Edi; Michael, Matar A; Kozlovsky, Nitzan; Kaplan, Zeev; Cohen, Hagit

2008-01-01

There is mounting evidence to support the concept that education is associated with the formation of a functional reserve in the brain, a process that appears to provide some protection against certain aspects of severe central nervous system disorders. The goal of this study was to examine whether learning prevents psychosis-like behaviour in an animal model of schizophrenia. A series of behavioural tasks were used to assess olfactory learning-induced protection against the effects of NMDA channel blocker, MK801. This blocker caused sensory-motor disturbances, spatial learning acquisition deficit, and swimming strategy alterations in pseudo-trained and naive rats, but had a considerably lesser effect on trained rats. In sharp contrast, olfactory learning provided no protection against d-amphetamine application. Our data support the notion that learning-induced protection against schizophrenic behaviour is maintained by non-NMDA-mediated enhanced activation of local connections in the relevant cortical networks.

Neuronal Nitric-Oxide Synthase Deficiency Impairs the Long-Term Memory of Olfactory Fear Learning and Increases Odor Generalization

ERIC Educational Resources Information Center

Pavesi, Eloisa; Heldt, Scott A.; Fletcher, Max L.

2013-01-01

Experience-induced changes associated with odor learning are mediated by a number of signaling molecules, including nitric oxide (NO), which is predominantly synthesized by neuronal nitric oxide synthase (nNOS) in the brain. In the current study, we investigated the role of nNOS in the acquisition and retention of conditioned olfactory fear. Mice…

Olfactory Interference during Inhibitory Backward Pairing in Honey Bees

PubMed Central

Dacher, Matthieu; Smith, Brian H.

2008-01-01

Background Restrained worker honey bees are a valuable model for studying the behavioral and neural bases of olfactory plasticity. The proboscis extension response (PER; the proboscis is the mouthpart of honey bees) is released in response to sucrose stimulation. If sucrose stimulation is preceded one or a few times by an odor (forward pairing), the bee will form a memory for this association, and subsequent presentations of the odor alone are sufficient to elicit the PER. However, backward pairing between the two stimuli (sucrose, then odor) has not been studied to any great extent in bees, although the vertebrate literature indicates that it elicits a form of inhibitory plasticity. Methodology/Principal Findings If hungry bees are fed with sucrose, they will release a long lasting PER; however, this PER can be interrupted if an odor is presented 15 seconds (but not 7 or 30 seconds) after the sucrose (backward pairing). We refer to this previously unreported process as olfactory interference. Bees receiving this 15 second backward pairing show reduced performance after a subsequent single forward pairing (excitatory conditioning) trial. Analysis of the results supported a relationship between olfactory interference and a form of backward pairing-induced inhibitory learning/memory. Injecting the drug cimetidine into the deutocerebrum impaired olfactory interference. Conclusions/Significance Olfactory interference depends on the associative link between odor and PER, rather than between odor and sucrose. Furthermore, pairing an odor with sucrose can lead either to association of this odor to PER or to the inhibition of PER by this odor. Olfactory interference may provide insight into processes that gate how excitatory and inhibitory memories for odor-PER associations are formed. PMID:18946512

Selective impairment of subcategories of long-term memory in mice with hippocampal lesions accessed by the olfactory tubing maze.

PubMed

Chaillan, F A; Marchetti, E; Soumireu-Mourat, B; Roman, F S

2005-03-30

A new apparatus, the olfactory tubing maze for mice, was developed recently to study learning and memory processes in mice in regard to their ethological abilities. As in humans, BALB/c mice with selective bilateral lesions of the hippocampal formation showed selective impairment of subcategories of long-term memory when tested with the olfactory tubing maze. After three learning sessions, control mice reached a high percentage of correct responses. They consistently made the olfactory-reward associations, but antero-dorsal and postero-ventral hippocampal-lesioned mice did not. However, all lesioned mice learned the paradigm and the timing of the task as fast and as well as control mice. These data suggest that the olfactory tubing maze can be used to study subcategories of memory, such as declarative and non-declarative memory, which are similar in some respects to those observed in humans. Consequently, possible memory effects of classical approaches (i.e., pharmacological or lesion studies) or genetic modifications in transgenic or gene-targeting mice can be effectively analyzed using this new apparatus.

Acute ethanol ingestion impairs appetitive olfactory learning and odor discrimination in the honey bee

PubMed Central

Mustard, Julie A; Wright, Geraldine A; Edgar, Elaina A; Mazade, Reece E.; Wu, Chen; Lillvis, Joshua L

2008-01-01

Invertebrates are valuable models for increasing our understanding of the effects of ethanol on the nervous system, but most studies on invertebrates and ethanol have focused on the effects of ethanol on locomotor behavior. In this work we investigate the influence of an acute dose of ethanol on appetitive olfactory learning in the honey bee (Apis mellifera), a model system for learning and memory. Adult worker honey bees were fed a range of doses (2.5, 5, 10 or 25%) of ethanol and then conditioned to associate an odor with a sucrose reward using either a simple or differential conditioning paradigm. Consumption of ethanol before conditioning significantly reduced both the rate of acquisition and the asymptotic strength of the association. Honey bees also exhibited a dose dependent reduction in arousal/attention during conditioning. Consumption of ethanol after conditioning did not affect recall 24 h later. The observed deficits in acquisition were not due to the affect of ethanol on gustatory sensitivity or motor function. However, honey bees given higher doses of ethanol had difficulty discriminating amongst different odors suggesting that ethanol consumption influences olfactory processing. Taken together, these results demonstrate that an acute dose of ethanol affects appetitive learning and olfactory perception in the honey bee. PMID:18723103

Side-Specificity of Olfactory Learning in the Honeybee: Generalization between Odors and Sides

PubMed Central

Sandoz, Jean-Christophe; Menzel, Randolf

2001-01-01

Honeybees (Apis mellifera) can be trained to associate an odor stimulus with a sucrose reward. The neural structures involved in the detection and integration of olfactory stimuli are represented bilaterally in the brain. Little is known about the respective roles of the two sides of the brain in olfactory learning. Does each side learn independently of the other, or do they communicate, and if so, to what extent and at what level of neural integration? We addressed these questions using the proboscis extension response (PER) conditioning paradigm applied in a preparation that allows the separation of the two input sides during olfactory stimulations. Bees conditioned to two odorants A and B, one being learned on each side (A+/B+ training), showed in extinction tests rather unspecific responses: They responded to both odorants on both sides. This could be attributable to either a transfer of the learned information between sides, or to a generalization between odorants on each side. By subjecting bees to conditioning on one side only (A+/0 training), we found that the learned information is indeed transferred between sides. However, when bees were trained explicitly to give opposite values to the two odorants on the two sides (A+B−/B+A− training), they showed clear side-specific response patterns to these odorants. These results are used in the elaboration of a functional model of laterality of olfactory learning and memory processing in the honeybee brain. PMID:11584076

No evidence for visual context-dependency of olfactory learning in Drosophila

NASA Astrophysics Data System (ADS)

Yarali, Ayse; Mayerle, Moritz; Nawroth, Christian; Gerber, Bertram

2008-08-01

How is behaviour organised across sensory modalities? Specifically, we ask concerning the fruit fly Drosophila melanogaster how visual context affects olfactory learning and recall and whether information about visual context is getting integrated into olfactory memory. We find that changing visual context between training and test does not deteriorate olfactory memory scores, suggesting that these olfactory memories can drive behaviour despite a mismatch of visual context between training and test. Rather, both the establishment and the recall of olfactory memory are generally facilitated by light. In a follow-up experiment, we find no evidence for learning about combinations of odours and visual context as predictors for reinforcement even after explicit training in a so-called biconditional discrimination task. Thus, a ‘true’ interaction between visual and olfactory modalities is not evident; instead, light seems to influence olfactory learning and recall unspecifically, for example by altering motor activity, alertness or olfactory acuity.

Preservation of Essential Odor-Guided Behaviors and Odor-Based Reversal Learning after Targeting Adult Brain Serotonin Synthesis.

PubMed

Carlson, Kaitlin S; Whitney, Meredith S; Gadziola, Marie A; Deneris, Evan S; Wesson, Daniel W

2016-01-01

The neurotransmitter serotonin (5-HT) is considered a powerful modulator of sensory system organization and function in a wide range of animals. The olfactory system is innervated by midbrain 5-HT neurons into both its primary and secondary odor-processing stages. Facilitated by this circuitry, 5-HT and its receptors modulate olfactory system function, including odor information input to the olfactory bulb. It is unknown, however, whether the olfactory system requires 5-HT for even its most basic behavioral functions. To address this question, we established a conditional genetic approach to specifically target adult brain tryptophan hydroxylase 2 ( Tph2 ), encoding the rate-limiting enzyme in brain 5-HT synthesis, and nearly eliminate 5-HT from the mouse forebrain. Using this novel model, we investigated the behavior of 5-HT-depleted mice during performance in an olfactory go/no-go task. Surprisingly, the near elimination of 5-HT from the forebrain, including the olfactory bulbs, had no detectable effect on the ability of mice to perform the odor-based task. Tph2 -targeted mice not only were able to learn the task, but also had levels of odor acuity similar to those of control mice when performing coarse odor discrimination. Both groups of mice spent similar amounts of time sampling odors during decision-making. Furthermore, odor reversal learning was identical between 5-HT-depleted and control mice. These results suggest that 5-HT neurotransmission is not necessary for the most essential aspects of olfaction, including odor learning, discrimination, and certain forms of cognitive flexibility.

Mammalian social odours: attraction and individual recognition

PubMed Central

Brennan, Peter A; Kendrick, Keith M

2006-01-01

Mammalian social systems rely on signals passed between individuals conveying information including sex, reproductive status, individual identity, ownership, competitive ability and health status. Many of these signals take the form of complex mixtures of molecules sensed by chemosensory systems and have important influences on a variety of behaviours that are vital for reproductive success, such as parent–offspring attachment, mate choice and territorial marking. This article aims to review the nature of these chemosensory cues and the neural pathways mediating their physiological and behavioural effects. Despite the complexities of mammalian societies, there are instances where single molecules can act as classical pheromones attracting interest and approach behaviour. Chemosignals with relatively high volatility can be used to signal at a distance and are sensed by the main olfactory system. Most mammals also possess a vomeronasal system, which is specialized to detect relatively non-volatile chemosensory cues following direct contact. Single attractant molecules are sensed by highly specific receptors using a labelled line pathway. These act alongside more complex mixtures of signals that are required to signal individual identity. There are multiple sources of such individuality chemosignals, based on the highly polymorphic genes of the major histocompatibility complex (MHC) or lipocalins such as the mouse major urinary proteins. The individual profile of volatile components that make up an individual odour signature can be sensed by the main olfactory system, as the pattern of activity across an array of broadly tuned receptor types. In addition, the vomeronasal system can respond highly selectively to non-volatile peptide ligands associated with the MHC, acting at the V2r class of vomeronasal receptor. The ability to recognize individuals or their genetic relatedness plays an important role in mammalian social behaviour. Thus robust systems for olfactory learning and recognition of chemosensory individuality have evolved, often associated with major life events, such as mating, parturition or neonatal development. These forms of learning share common features, such as increased noradrenaline evoked by somatosensory stimulation, which results in neural changes at the level of the olfactory bulb. In the main olfactory bulb, these changes are likely to refine the pattern of activity in response to the learned odour, enhancing its discrimination from those of similar odours. In the accessory olfactory bulb, memory formation is hypothesized to involve a selective inhibition, which disrupts the transmission of the learned chemosignal from the mating male. Information from the main olfactory and vomeronasal systems is integrated at the level of the corticomedial amygdala, which forms the most important pathway by which social odours mediate their behavioural and physiological effects. Recent evidence suggests that this region may also play an important role in the learning and recognition of social chemosignals. PMID:17118924

Use of an innovative T-tube maze assay and the proboscis extension response assay to assess sublethal effects of GM products and pesticides on learning capacity of the honey bee Apis mellifera L.

PubMed

Han, Peng; Niu, Chang-Ying; Lei, Chao-Liang; Cui, Jin-Jie; Desneux, Nicolas

2010-11-01

Transgenic Cry1Ac+CpTI cotton (CCRI41) is a promising cotton cultivar throughout China but side effects and especially sublethal effects of this transgenic cultivar on beneficial insects remain poorly studied. More specifically potential sublethal effects on behavioural traits of the honey bee Apis mellifera L. have not been formally assessed despite the importance of honey bees for pollination. The goal of our study was to assess potential effects of CCRI41 cotton pollen on visual and olfactory learning by honey bees. After a 7-day oral chronic exposure to honey mixed with either CCRI41 pollen, imidacloprid-treated conventional pollen (used as positive sublethal control) or conventional pollen (control), learning performance was evaluated by the classical proboscis extension reflex (PER) procedure as well as a T-tube maze test. The latter assay was designed as a new device to assess potential side effects of pesticides on visual associative learning of honey bees. These two procedures were complementary because the former focused on olfactory learning while the latter was involved in visual learning based on visual orientation ability. Oral exposure to CCRI41 pollen did not affect learning capacities of honey bees in both the T-tube maze and PER tests. However, exposure to imidacloprid resulted in reduced visual learning capacities in T-tube maze evaluation and decreased olfactory learning performances measured with PER. The implications of these results are discussed in terms of risks of transgenic CCRI41 cotton crops for honey bees.

Social Modulation of Associative Fear Learning by Pheromone Communication

ERIC Educational Resources Information Center

Bredy, Timothy W.; Barad, Mark

2009-01-01

Mice communicate through visual, vocal, and olfactory cues that influence innate, nonassociative behavior. We here report that exposure to a recently fear-conditioned familiar mouse impairs acquisition of conditioned fear and facilitates fear extinction, effects mimicked by both an olfactory chemosignal emitted by a recently fear-conditioned…

Olfactory bulb size, odor discrimination and magnetic insensitivity in hummingbirds.

PubMed

Ioalé, P; Papi, F

1989-05-01

Relative olfactory bulb size with respect to telencephalic hemispheres (olfactory ratio) was measured in five species of hummingbirds. Trochiliformes were found to be next to last among 25 avian orders with respect to olfactory bulb development. One hummingbird species, the White-vented Violetear (Colibri serrirostris), was trained in a successive go/no-go discrimination task, and learned to feed or not to feed from a container dependent on the olfactory stimuli associated with it. Test birds learned to discriminate amyl acetate vs. turpentine essence, jasmine essence vs. lavender essence, eucalyptus essence vs. no odor, beta-ionone vs. no odor, carvone vs. eucalyptol. In contrast, 1-phenylethanol vs. beta-ionone discrimination, two odorants which appear similar to humans, was unsuccessful. Using a similar procedure, attempts were made to condition a White-vented Violetear and a Versicolored Emerald (Amazilia versicolor) to magnetic stimuli. The birds were unable to discriminate between a normal field and an oscillating field (square wave, 1 Hz, amplitude +/- 0.40 G).

Associative learning for danger avoidance nullifies innate positive chemotaxis to host olfactory stimuli in a parasitic wasp

NASA Astrophysics Data System (ADS)

Benelli, Giovanni; Stefanini, Cesare; Giunti, Giulia; Geri, Serena; Messing, Russell H.; Canale, Angelo

2014-09-01

Animals rely on associative learning for a wide range of purposes, including danger avoidance. This has been demonstrated for several insects, including cockroaches, mosquitoes, drosophilid flies, paper wasps, stingless bees, bumblebees and honeybees, but less is known for parasitic wasps. We tested the ability of Psyttalia concolor (Hymenoptera: Braconidae) females to associate different dosages of two innately attractive host-induced plant volatiles (HIPVs), ethyl octanoate and decanal, with danger (electric shocks). We conducted an associative treatment involving odours and shocks and two non-associative controls involving shocks but not odours and odours but not shocks. In shock-only and odour-only trained wasps, females preferred on HIPV-treated than on blank discs. In associative-trained wasps, however, P. concolor's innate positive chemotaxis for HIPVs was nullified (lowest HIPV dosage tested) or reversed (highest HIPV dosage tested). This is the first report of associative learning of olfactory cues for danger avoidance in parasitic wasps, showing that the effects of learning can override innate positive chemotaxes.

MiR-132 regulated olfactory bulb proteins linked to olfactory learning in greater short-nosed fruit bat Cynopterus sphinx.

PubMed

Mukilan, Murugan; Rajathei, David Mary; Jeyaraj, Edwin; Kayalvizhi, Nagarajan; Rajan, Koilmani Emmanuvel

2018-05-30

Earlier, we showed that micro RNA-132 (miR-132) regulate the immediate early genes (IEGs) in the olfactory bulb (OB) of fruit bat Cynopterus sphinx during olfactory learning. This study was designed to examine whether the miR-132 regulate other proteins in OB during olfactory learning. To test this, miR-132 anti-sense oligodeoxynucleotide (AS-ODN) was delivered to the OB and then trained to novel odor. The 2-dimensional gel electrophoresis analysis showed that inhibition of miR-132 altered olfactory training induced expression of 321 proteins. Further, liquid chromatography-mass spectrometry (LC-MS/MS) analysis reveals the identity of differently expressed proteins such as phosphoribosyl transferase domain containing protein (PRTFDC 1), Sorting nexin-8 (SNX8), Creatine kinase B-type (CKB) and Annexin A11 (ANX A11). Among them PRTFDC 1 showing 189 matching peptides with highest sequence coverage (67.0%) and protein-protein interaction analysis showed that PRTFDC 1 is a homolog of hypoxanthine phosphoribosyltransferase-1 (HPRT-1). Subsequent immunohistochemical analysis (IHC) showed that inhibition of miR-132 down-regulated HPRT expression in OB of C. sphinx. In addition, western blot analysis depicts that HPRT, serotonin transporter (SERT), N-methyl-d-asparate (NMDA) receptors (2A,B) were down-regulated, but not altered in OB of non-sense oligodeoxynucleotide (NS-ODN) infused groups. These analyses suggest that miR-132 regulates the process of olfactory learning and memory formation through SERT and NMDA receptors signalling, which is possibly associated with the PRTFDC1-HPRT interaction. Copyright © 2017. Published by Elsevier B.V.

Circuit oscillations in odor perception and memory.

PubMed

Kay, Leslie M

2014-01-01

Olfactory system neural oscillations as seen in the local field potential have been studied for many decades. Recent research has shown that there is a functional role for the most studied gamma oscillations (40-100Hz in rats and mice, and 20Hz in insects), without which fine odor discrimination is poor. When these oscillations are increased artificially, fine discrimination is increased, and when rats learn difficult and highly overlapping odor discriminations, gamma is increased in power. Because of the depth of study on this oscillation, it is possible to point to specific changes in neural firing patterns as represented by the increase in gamma oscillation amplitude. However, we know far less about the mechanisms governing beta oscillations (15-30Hz in rats and mice), which are best associated with associative learning of responses to odor stimuli. These oscillations engage every part of the olfactory system that has so far been tested, plus the hippocampus, and the beta oscillation frequency band is the one that is most reliably coherent with other regions during odor processing. Respiratory oscillations overlapping with the theta frequency band (2-12Hz) are associated with odor sniffing and normal breathing in rats. They also show coupling in some circumstances between olfactory areas and rare coupling between the hippocampus and olfactory bulb. The latter occur in specific learning conditions in which coherence strength is negatively or positively correlated with performance, depending on the task. There is still much to learn about the role of neural oscillations in learning and memory, but techniques that have been brought to bear on gamma oscillations (current source density, computational modeling, slice physiology, behavioral studies) should deliver much needed knowledge of these events. © 2014 Elsevier B.V. All rights reserved.

Fragile X Mental Retardation Protein and Dendritic Local Translation of the Alpha Subunit of the Calcium/Calmodulin-Dependent Kinase II Messenger RNA Are Required for the Structural Plasticity Underlying Olfactory Learning.

PubMed

Daroles, Laura; Gribaudo, Simona; Doulazmi, Mohamed; Scotto-Lomassese, Sophie; Dubacq, Caroline; Mandairon, Nathalie; Greer, Charles August; Didier, Anne; Trembleau, Alain; Caillé, Isabelle

2016-07-15

In the adult brain, structural plasticity allowing gain or loss of synapses remodels circuits to support learning. In fragile X syndrome, the absence of fragile X mental retardation protein (FMRP) leads to defects in plasticity and learning deficits. FMRP is a master regulator of local translation but its implication in learning-induced structural plasticity is unknown. Using an olfactory learning task requiring adult-born olfactory bulb neurons and cell-specific ablation of FMRP, we investigated whether learning shapes adult-born neuron morphology during their synaptic integration and its dependence on FMRP. We used alpha subunit of the calcium/calmodulin-dependent kinase II (αCaMKII) mutant mice with altered dendritic localization of αCaMKII messenger RNA, as well as a reporter of αCaMKII local translation to investigate the role of this FMRP messenger RNA target in learning-dependent structural plasticity. Learning induces profound changes in dendritic architecture and spine morphology of adult-born neurons that are prevented by ablation of FMRP in adult-born neurons and rescued by an metabotropic glutamate receptor 5 antagonist. Moreover, dendritically translated αCaMKII is necessary for learning and associated structural modifications and learning triggers an FMRP-dependent increase of αCaMKII dendritic translation in adult-born neurons. Our results strongly suggest that FMRP mediates structural plasticity of olfactory bulb adult-born neurons to support olfactory learning through αCaMKII local translation. This reveals a new role for FMRP-regulated dendritic local translation in learning-induced structural plasticity. This might be of clinical relevance for the understanding of critical periods disruption in autism spectrum disorder patients, among which fragile X syndrome is the primary monogenic cause. Copyright © 2016 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Social modulation of associative fear learning by pheromone communication

PubMed Central

Bredy, Timothy W.; Barad, Mark

2009-01-01

Mice communicate through visual, vocal, and olfactory cues that influence innate, nonassociative behavior. We here report that exposure to a recently fear-conditioned familiar mouse impairs acquisition of conditioned fear and facilitates fear extinction, effects mimicked by both an olfactory chemosignal emitted by a recently fear-conditioned familiar mouse and by the putative stress-related anxiogenic pheromone β-phenylethylamine (β-PEA). Together, these findings suggest social modulation of higher-order cognitive processing through pheromone communication and support the concurrent excitor hypothesis of extinction learning. PMID:19117912

Social modulation of associative fear learning by pheromone communication.

PubMed

Bredy, Timothy W; Barad, Mark

2009-01-01

Mice communicate through visual, vocal, and olfactory cues that influence innate, nonassociative behavior. We here report that exposure to a recently fear-conditioned familiar mouse impairs acquisition of conditioned fear and facilitates fear extinction, effects mimicked by both an olfactory chemosignal emitted by a recently fear-conditioned familiar mouse and by the putative stress-related anxiogenic pheromone beta-phenylethylamine (beta-PEA). Together, these findings suggest social modulation of higher-order cognitive processing through pheromone communication and support the concurrent excitor hypothesis of extinction learning.

Associative Processes in Early Olfactory Preference Acquisition

PubMed Central

Sullivan, Regina M.; Wilson, Donald A.; Leon, Michael

2007-01-01

Acquisition of behavioral conditioned responding and learned odor preferences during olfactory classical conditioning in rat pups requires forward or simultaneous pairings of the conditioned stimulus (CS) and the unconditioned stimulus (US). Other temporal relationships between the CS and US do not usually result in learning. The present study examined the influence of this CS-US relationship upon the neural olfactory bulb modifications that are acquired during early classical conditioning. Wistar rat pups were trained from Postnatal Days (PN) 1-18 with either forward (odor overlapping temporally with reinforcing stroking) or backward (stroking followed by odor) CS-US pairings. On PN 19, pups received either a behavioral odor preference test to the odor CS or an injection of 14C 2-DG and exposure to the odor CS, or olfactory bulb single unit responses were recorded in response to exposure to the odor CS. Only pups that received forward presentations of the CS and US exhibited both a preference for the CS and modified olfactory bulb neural responses to the CS. These results, then, suggest that the modified olfactory bulb neural responses acquired during classical conditioning are guided by the same temporal constraints as those which govern the acquisition of behavioral conditioned responses. PMID:17572798

Use of an innovative T-tube maze assay and the proboscis extension response assay to assess sublethal effects of GM products and pesticides on learning capacity of the honey bee Apis mellifera L.

PubMed Central

Han, Peng; Lei, Chao-Liang; Cui, Jin-Jie; Desneux, Nicolas

2010-01-01

Transgenic Cry1Ac+CpTI cotton (CCRI41) is a promising cotton cultivar throughout China but side effects and especially sublethal effects of this transgenic cultivar on beneficial insects remain poorly studied. More specifically potential sublethal effects on behavioural traits of the honey bee Apis mellifera L. have not been formally assessed despite the importance of honey bees for pollination. The goal of our study was to assess potential effects of CCRI41 cotton pollen on visual and olfactory learning by honey bees. After a 7-day oral chronic exposure to honey mixed with either CCRI41 pollen, imidacloprid-treated conventional pollen (used as positive sublethal control) or conventional pollen (control), learning performance was evaluated by the classical proboscis extension reflex (PER) procedure as well as a T-tube maze test. The latter assay was designed as a new device to assess potential side effects of pesticides on visual associative learning of honey bees. These two procedures were complementary because the former focused on olfactory learning while the latter was involved in visual learning based on visual orientation ability. Oral exposure to CCRI41 pollen did not affect learning capacities of honey bees in both the T-tube maze and PER tests. However, exposure to imidacloprid resulted in reduced visual learning capacities in T-tube maze evaluation and decreased olfactory learning performances measured with PER. The implications of these results are discussed in terms of risks of transgenic CCRI41 cotton crops for honey bees. PMID:20872243

The Olfactory Mosaic: Bringing an Olfactory Network Together for Odor Perception.

PubMed

Courtiol, Emmanuelle; Wilson, Donald A

2017-01-01

Olfactory perception and its underlying neural mechanisms are not fixed, but rather vary over time, dependent on various parameters such as state, task, or learning experience. In olfaction, one of the primary sensory areas beyond the olfactory bulb is the piriform cortex. Due to an increasing number of functions attributed to the piriform cortex, it has been argued to be an associative cortex rather than a simple primary sensory cortex. In fact, the piriform cortex plays a key role in creating olfactory percepts, helping to form configural odor objects from the molecular features extracted in the nose. Moreover, its dynamic interactions with other olfactory and nonolfactory areas are also critical in shaping the olfactory percept and resulting behavioral responses. In this brief review, we will describe the key role of the piriform cortex in the larger olfactory perceptual network, some of the many actors of this network, and the importance of the dynamic interactions among the piriform-trans-thalamic and limbic pathways.

Long-term enhancement of synaptic transmission between antennal lobe and mushroom body in cultured Drosophila brain.

PubMed

Ueno, Kohei; Naganos, Shintaro; Hirano, Yukinori; Horiuchi, Junjiro; Saitoe, Minoru

2013-01-01

In Drosophila, the mushroom body (MB) is a critical brain structure for olfactory associative learning. During aversive conditioning, the MBs are thought to associate odour signals, conveyed by projection neurons (PNs) from the antennal lobe (AL), with shock signals conveyed through ascending fibres of the ventral nerve cord (AFV). Although synaptic transmission between AL and MB might play a crucial role for olfactory associative learning, its physiological properties have not been examined directly. Using a cultured Drosophila brain expressing a Ca(2+) indicator in the MBs, we investigated synaptic transmission and plasticity at the AL-MB synapse. Following stimulation with a glass micro-electrode, AL-induced Ca(2+) responses in the MBs were mediated through Drosophila nicotinic acetylcholine receptors (dnAChRs), while AFV-induced Ca(2+) responses were mediated through Drosophila NMDA receptors (dNRs). AL-MB synaptic transmission was enhanced more than 2 h after the simultaneous 'associative-stimulation' of AL and AFV, and such long-term enhancement (LTE) was specifically formed at the AL-MB synapses but not at the AFV-MB synapses. AL-MB LTE was not induced by intense stimulation of the AL alone, and the LTE decays within 60 min after subsequent repetitive AL stimulation. These phenotypes of associativity, input specificity and persistence of AL-MB LTE are highly reminiscent of olfactory memory. Furthermore, similar to olfactory aversive memory, AL-MB LTE formation required activation of the Drosophila D1 dopamine receptor, DopR, along with dnAChR and dNR during associative stimulations. These physiological and genetic analogies indicate that AL-MB LTE might be a relevant cellular model for olfactory memory.

Long-term enhancement of synaptic transmission between antennal lobe and mushroom body in cultured Drosophila brain

PubMed Central

Ueno, Kohei; Naganos, Shintaro; Hirano, Yukinori; Horiuchi, Junjiro; Saitoe, Minoru

2013-01-01

In Drosophila, the mushroom body (MB) is a critical brain structure for olfactory associative learning. During aversive conditioning, the MBs are thought to associate odour signals, conveyed by projection neurons (PNs) from the antennal lobe (AL), with shock signals conveyed through ascending fibres of the ventral nerve cord (AFV). Although synaptic transmission between AL and MB might play a crucial role for olfactory associative learning, its physiological properties have not been examined directly. Using a cultured Drosophila brain expressing a Ca2+ indicator in the MBs, we investigated synaptic transmission and plasticity at the AL–MB synapse. Following stimulation with a glass micro-electrode, AL-induced Ca2+ responses in the MBs were mediated through Drosophila nicotinic acetylcholine receptors (dnAChRs), while AFV-induced Ca2+ responses were mediated through Drosophila NMDA receptors (dNRs). AL–MB synaptic transmission was enhanced more than 2 h after the simultaneous ‘associative-stimulation’ of AL and AFV, and such long-term enhancement (LTE) was specifically formed at the AL–MB synapses but not at the AFV–MB synapses. AL–MB LTE was not induced by intense stimulation of the AL alone, and the LTE decays within 60 min after subsequent repetitive AL stimulation. These phenotypes of associativity, input specificity and persistence of AL–MB LTE are highly reminiscent of olfactory memory. Furthermore, similar to olfactory aversive memory, AL–MB LTE formation required activation of the Drosophila D1 dopamine receptor, DopR, along with dnAChR and dNR during associative stimulations. These physiological and genetic analogies indicate that AL–MB LTE might be a relevant cellular model for olfactory memory. PMID:23027817

Color Modulates Olfactory Learning in Honeybees by an Occasion-Setting Mechanism

ERIC Educational Resources Information Center

Mota, Theo; Giurfa, Martin; Sandoz, Jean-Christophe

2011-01-01

A sophisticated form of nonelemental learning is provided by occasion setting. In this paradigm, animals learn to disambiguate an uncertain conditioned stimulus using alternative stimuli that do not enter into direct association with the unconditioned stimulus. For instance, animals may learn to discriminate odor rewarded from odor nonrewarded…

An olfactory subsystem that detects carbon disulfide and mediates food-related social learning.

PubMed

Munger, Steven D; Leinders-Zufall, Trese; McDougall, Lisa M; Cockerham, Renee E; Schmid, Andreas; Wandernoth, Petra; Wennemuth, Gunther; Biel, Martin; Zufall, Frank; Kelliher, Kevin R

2010-08-24

Olfactory signals influence social interactions in a variety of species. In mammals, pheromones and other social cues can promote mating or aggression behaviors; can communicate information about social hierarchies, genetic identity and health status; and can contribute to associative learning. However, the molecular, cellular, and neural mechanisms underlying many olfactory-mediated social interactions remain poorly understood. Here, we report that a specialized olfactory subsystem that includes olfactory sensory neurons (OSNs) expressing the receptor guanylyl cyclase GC-D, the cyclic nucleotide-gated channel subunit CNGA3, and the carbonic anhydrase isoform CAII (GC-D(+) OSNs) is required for the acquisition of socially transmitted food preferences (STFPs) in mice. Using electrophysiological recordings from gene-targeted mice, we show that GC-D(+) OSNs are highly sensitive to the volatile semiochemical carbon disulfide (CS(2)), a component of rodent breath and a known social signal mediating the acquisition of STFPs. Olfactory responses to CS(2) are drastically reduced in mice lacking GC-D, CNGA3, or CAII. Disruption of this sensory transduction cascade also results in a failure to acquire STFPs from either live or surrogate demonstrator mice or to exhibit hippocampal correlates of STFP retrieval. Our findings indicate that GC-D(+) OSNs detect chemosignals that facilitate food-related social interactions. Copyright 2010 Elsevier Ltd. All rights reserved.

Upregulation of Neurotrophic Factors Selectively in Frontal Cortex in Response to Olfactory Discrimination Learning

PubMed Central

Naimark, Ari; Barkai, Edi; Matar, Michael A.; Kaplan, Zeev; Kozlovsky, Nitzan; Cohen, Hagit

2007-01-01

We have previously shown that olfactory discrimination learning is accompanied by several forms of long-term enhancement in synaptic connections between layer II pyramidal neurons selectively in the piriform cortex. This study sought to examine whether the previously demonstrated olfactory-learning-task-induced modifications are preceded by suitable changes in the expression of mRNA for neurotrophic factors and in which brain areas this occurs. Rats were trained to discriminate positive cues in pair of odors for a water reward. The relationship between the learning task and local levels of mRNA for brain-derived neurotrophic factor, tyrosine kinase B, nerve growth factor, and neurotrophin-3 in the frontal cortex, hippocampal subregions, and other regions were assessed 24 hours post olfactory learning. The olfactory discrimination learning activated production of endogenous neurotrophic factors and induced their signal transduction in the frontal cortex, but not in other brain areas. These findings suggest that different brain areas may be preferentially involved in different learning/memory tasks. PMID:17710248

A Synergistic Transcriptional Regulation of Olfactory Genes Drives Blood-Feeding Associated Complex Behavioral Responses in the Mosquito Anopheles culicifacies.

PubMed

Das De, Tanwee; Thomas, Tina; Verma, Sonia; Singla, Deepak; Chauhan, Charu; Srivastava, Vartika; Sharma, Punita; Kumari, Seena; Tevatiya, Sanjay; Rani, Jyoti; Hasija, Yasha; Pandey, Kailash C; Dixit, Rajnikant

2018-01-01

Decoding the molecular basis of host seeking and blood feeding behavioral evolution/adaptation in the adult female mosquitoes may provide an opportunity to design new molecular strategy to disrupt human-mosquito interactions. Although there is a great progress in the field of mosquito olfaction and chemo-detection, little is known about the sex-specific evolution of the specialized olfactory system of adult female mosquitoes that enables them to drive and manage the complex blood-feeding associated behavioral responses. A comprehensive RNA-Seq analysis of prior and post blood meal olfactory system of An. culicifacies mosquito revealed a minor but unique change in the nature and regulation of key olfactory genes that may play a pivotal role in managing diverse behavioral responses. Based on age-dependent transcriptional profiling, we further demonstrated that adult female mosquito's chemosensory system gradually learned and matured to drive the host-seeking and blood feeding behavior at the age of 5-6 days. A time scale expression analysis of Odorant Binding Proteins (OBPs) unravels unique association with a late evening to midnight peak biting time. Blood meal-induced switching of unique sets of OBP genes and Odorant Receptors (Ors) expression coincides with the change in the innate physiological status of the mosquitoes. Blood meal follows up experiments further provide enough evidence that how a synergistic and concurrent action of OBPs-Ors may drive "prior and post blood meal" associated complex behavioral events. A dominant expression of two sensory appendages proteins (SAP-1 & SAP2) in the legs of An. culicifacies suggests that this mosquito species may draw an extra advantage of having more sensitive appendages than An. stephensi , an urban malarial vector in the Indian subcontinents. Finally, our molecular modeling analysis predicts crucial amino acid residues for future functional characterization of the sensory appendages proteins which may play a central role in regulating multiple behaviors of An. culicifacies mosquito. SIGNIFICANCE   Evolution and adaptation of blood feeding behavior not only favored the reproductive success of adult female mosquitoes but also make them important disease-transmitting vectors. An environmental exposure after emergence may favor the broadly tuned olfactory system of mosquitoes to drive complex behavioral responses. But, how these olfactory derived genetic factors manage female specific "pre and post" blood meal associated complex behavioral responses are not well known. Our findings suggest that a synergistic action of olfactory factors may govern an innate to prime learning strategy to facilitate rapid blood meal acquisition and downstream behavioral activities. A species-specific transcriptional profiling and an in-silico analysis predict that "sensory appendages protein" may be a unique target to design disorientation strategy against the mosquito Anopheles culicifacies .

Honey Bees Modulate Their Olfactory Learning in the Presence of Hornet Predators and Alarm Component.

PubMed

Wang, Zhengwei; Qu, Yufeng; Dong, Shihao; Wen, Ping; Li, Jianjun; Tan, Ken; Menzel, Randolf

2016-01-01

In Southeast Asia the native honey bee species Apis cerana is often attacked by hornets (Vespa velutina), mainly in the period from April to November. During the co-evolution of these two species honey bees have developed several strategies to defend themselves such as learning the odors of hornets and releasing alarm components to inform other mates. However, so far little is known about whether and how honey bees modulate their olfactory learning in the presence of the hornet predator and alarm components of honey bee itself. In the present study, we test for associative olfactory learning of A. cerana in the presence of predator odors, the alarm pheromone component isopentyl acetate (IPA), or a floral odor (hexanal) as a control. The results show that bees can detect live hornet odors, that there is almost no association between the innately aversive hornet odor and the appetitive stimulus sucrose, and that IPA is less well associated with an appetitive stimulus when compared with a floral odor. In order to imitate natural conditions, e.g. when bees are foraging on flowers and a predator shows up, or alarm pheromone is released by a captured mate, we tested combinations of the hornet odor and floral odor, or IPA and floral odor. Both of these combinations led to reduced learning scores. This study aims to contribute to a better understanding of the prey-predator system between A. cerana and V. velutina.

Differential associative training enhances olfactory acuity in Drosophila melanogaster.

PubMed

Barth, Jonas; Dipt, Shubham; Pech, Ulrike; Hermann, Moritz; Riemensperger, Thomas; Fiala, André

2014-01-29

Training can improve the ability to discriminate between similar, confusable stimuli, including odors. One possibility of enhancing behaviorally expressed discrimination (i.e., sensory acuity) relies on differential associative learning, during which animals are forced to detect the differences between similar stimuli. Drosophila represents a key model organism for analyzing neuronal mechanisms underlying both odor processing and olfactory learning. However, the ability of flies to enhance fine discrimination between similar odors through differential associative learning has not been analyzed in detail. We performed associative conditioning experiments using chemically similar odorants that we show to evoke overlapping neuronal activity in the fly's antennal lobes and highly correlated activity in mushroom body lobes. We compared the animals' performance in discriminating between these odors after subjecting them to one of two types of training: either absolute conditioning, in which only one odor is reinforced, or differential conditioning, in which one odor is reinforced and a second odor is explicitly not reinforced. First, we show that differential conditioning decreases behavioral generalization of similar odorants in a choice situation. Second, we demonstrate that this learned enhancement in olfactory acuity relies on both conditioned excitation and conditioned inhibition. Third, inhibitory local interneurons in the antennal lobes are shown to be required for behavioral fine discrimination between the two similar odors. Fourth, differential, but not absolute, training causes decorrelation of odor representations in the mushroom body. In conclusion, differential training with similar odors ultimately induces a behaviorally expressed contrast enhancement between the two similar stimuli that facilitates fine discrimination.

Focal Uncaging of GABA Reveals a Temporally Defined Role for GABAergic Inhibition during Appetitive Associative Olfactory Conditioning in Honeybees

ERIC Educational Resources Information Center

Raccuglia, Davide; Mueller, Uli

2013-01-01

Throughout the animal kingdom, the inhibitory neurotransmitter ?-aminobutyric acid (GABA) is a key modulator of physiological processes including learning. With respect to associative learning, the exact time in which GABA interferes with the molecular events of learning has not yet been clearly defined. To address this issue, we used two…

Opposite effects depending on learning and memory demands in dorsomedial prefrontal cortex lesioned rats performing an olfactory task.

PubMed

Chaillan, F A; Marchetti, E; Delfosse, F; Roman, F S; Soumireu-Mourat, B

1997-01-01

In this study, the functional properties of the dorsomedial prefrontal cortex (dmPFC) of the rat were examined in two olfactory tasks. In a successive cue olfactory discrimination task, dmPFC lesioned animals improved performance across sessions more rapidly than operated control animals. In an olfactory task using fixed interval training, animals with similar lesions were impaired. Both effects, although opposite, can be explained by a temporal processing deficit. The present results seem to indicate that the dmPFC is required for timing, classified as part of non-declarative memory. As reference memory improved in the lesioned animals, the finding is that the dmPFC supports non-declarative memory and thus interacts with declarative memory in the long-term formation of the associations between a particular stimulus (olfactory cue) and particular responses.

Respective Role of the Dorsal Hippocampus and the Entorhinal Cortex during the Recombination of Previously Learned Olfactory-Tactile Associations in the Rat

ERIC Educational Resources Information Center

Boisselier, Lise; Ferry, Barbara; Gervais, Rémi

2017-01-01

The hippocampal formation has been extensively described as a key component for object recognition in conjunction with place and context. The present study aimed at describing neural mechanisms in the hippocampal formation that support olfactory-tactile (OT) object discrimination in a task where space and context were not taken into account. The…

Successful acquisition of an olfactory discrimination test by Asian elephants, Elephas maximus.

PubMed

Arvidsson, Josefin; Amundin, Mats; Laska, Matthias

2012-02-01

The present study demonstrates that Asian elephants, Elephas maximus, can successfully be trained to cooperate in an olfactory discrimination test based on a food-rewarded two-alternative instrumental conditioning procedure. The animals learned the basic principle of the test within only 60 trials and readily mastered intramodal stimulus transfer tasks. Further, they were capable of distinguishing between structurally related odor stimuli and remembered the reward value of previously learned odor stimuli after 2, 4, 8, and 16 weeks of recess without any signs of forgetting. The precision and consistency of the elephants' performance in tests of odor discrimination ability and long-term odor memory demonstrate the suitability of this method for assessing olfactory function in this proboscid species. An across-species comparison of several measures of olfactory learning capabilities such as speed of initial task acquisition and ability to master intramodal stimulus transfer tasks shows that Asian elephants are at least as good in their performance as mice, rats, and dogs, and clearly superior to nonhuman primates and fur seals. The results support the notion that Asian elephants may use olfactory cues for social communication and food selection and that the sense of smell may play an important role in the control of their behavior. Copyright © 2011 Elsevier Inc. All rights reserved.

Olfactory Dysfunction Is Associated with the Intake of Macronutrients in Korean Adults

PubMed Central

Kong, Il Gyu; Kim, So Young; Kim, Min-Su; Park, Bumjung; Kim, Jin-Hwan

2016-01-01

Background Olfactory function can impact food selection. However, few large population-based studies have investigated this effect across different age groups. The objective of this study was to assess the association between subjective olfactory dysfunction (anosmia or hyposmia) and macronutrient intake. Methods A total of 24,990 participants aged 20 to 98 years were evaluated based on data collected through the Korea National Health and Nutrition Examination Survey from 2008 through 2012. Olfactory dysfunction was surveyed using a self-reported questionnaire, and the nutritional status was assessed through a validated 24-hour recall method. Simple and multiple linear regression analyses with complex sampling were performed to evaluate the relationships between olfactory dysfunction and protein intake (daily protein intake/recommended protein intake [%]), carbohydrate intake (daily carbohydrate intake/total calories [%]), and fat intake (daily fat intake/total calories [%]) after adjusting for age, sex, body mass index, income, smoking history, alcohol consumption, and stress level. Results Olfactory dysfunction was reported by 5.4% of Korean adults and was found to be associated with decreased fat consumption (estimated value [EV] of fat intake [%] = -0.57, 95% confidence interval [CI] = -1.13 to -0.13, P = 0.045). A subgroup analysis according to age and sex revealed that among young females, olfactory dysfunction was associated with reduced fat consumption (EV = -2.30, 95% CI = -4.16 to -0.43, P = 0.016) and increased carbohydrate intake (EV = 2.80, 95% CI = 0.55 to 5.05, P = 0.015), and that among middle-aged females, olfactory dysfunction was also associated with reduced fat intake (EV = -1.26, 95% CI = -2.37 to -0.16, P = 0.025). In contrast, among young males, olfactory dysfunction was associated with reduced protein intake (EV = -26.41 95% CI = -45.14 to -7.69, P = 0.006). Conclusion Olfactory dysfunction was associated with reduced fat intake. Moreover, olfactory dysfunction exerted differential effects on eating behavior depending on age and sex. PMID:27723843

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri

PubMed Central

Stockton, Dara G.; Martini, Xavier; Patt, Joseph M.; Stelinski, Lukasz L.

2016-01-01

Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24–48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area being monitored. PMID:26930355

The Influence of Learning on Host Plant Preference in a Significant Phytopathogen Vector, Diaphorina citri.

PubMed

Stockton, Dara G; Martini, Xavier; Patt, Joseph M; Stelinski, Lukasz L

2016-01-01

Although specialist herbivorous insects are guided by innate responses to host plant cues, host plant preference may be influenced by experience and is not dictated by instinct alone. The effect of learning on host plant preference was examined in the Asian citrus psyllid, Diaphorina citri; vector of the causal agent of citrus greening disease or huanglongbing. We investigated: a) whether development on specific host plant species influenced host plant preference in mature D. citri; and b) the extent of associative learning in D. citri in the form of simple and compound conditioning. Learning was measured by cue selection in a 2-choice behavioral assay and compared to naïve controls. Our results showed that learned responses in D. citri are complex and diverse. The developmental host plant species influenced adult host plant preference, with female psyllids preferring the species on which they were reared. However, such preferences were subject to change with the introduction of an alternative host plant within 24-48 hrs, indicating a large degree of experience-dependent response plasticity. Additionally, learning occurred for multiple sensory modalities where novel olfactory and visual environmental cues were associated with the host plant. However, males and females displayed differing discriminatory abilities. In compound conditioning tasks, males exhibited recognition of a compound stimulus alone while females were capable of learning the individual components. These findings suggest D. citri are dynamic animals that demonstrate host plant preference based on developmental and adult experience and can learn to recognize olfactory and visual host plant stimuli in ways that may be sex specific. These experience-based associations are likely used by adults to locate and select suitable host plants for feeding and reproduction and may suggest the need for more tailored lures and traps, which reflect region-specific cultivars or predominate Rutaceae in the area being monitored.

Multimodal Floral Signals and Moth Foraging Decisions

PubMed Central

Riffell, Jeffrey A.; Alarcón, Ruben

2013-01-01

Background Combinations of floral traits – which operate as attractive signals to pollinators – act on multiple sensory modalities. For Manduca sexta hawkmoths, how learning modifies foraging decisions in response to those traits remains untested, and the contribution of visual and olfactory floral displays on behavior remains unclear. Methodology/Principal Findings Using M. sexta and the floral traits of two important nectar resources in southwestern USA, Datura wrightii and Agave palmeri, we examined the relative importance of olfactory and visual signals. Natural visual and olfactory cues from D. wrightii and A. palmeri flowers permits testing the cues at their native intensities and composition – a contrast to many studies that have used artificial stimuli (essential oils, single odorants) that are less ecologically relevant. Results from a series of two-choice assays where the olfactory and visual floral displays were manipulated showed that naïve hawkmoths preferred flowers displaying both olfactory and visual cues. Furthermore, experiments using A. palmeri flowers – a species that is not very attractive to hawkmoths – showed that the visual and olfactory displays did not have synergistic effects. The combination of olfactory and visual display of D. wrightii, however – a flower that is highly attractive to naïve hawkmoths – did influence the time moths spent feeding from the flowers. The importance of the olfactory and visual signals were further demonstrated in learning experiments in which experienced moths, when exposed to uncoupled floral displays, ultimately chose flowers based on the previously experienced olfactory, and not visual, signals. These moths, however, had significantly longer decision times than moths exposed to coupled floral displays. Conclusions/Significance These results highlight the importance of specific sensory modalities for foraging hawkmoths while also suggesting that they learn the floral displays as combinatorial signals and use the integrated floral traits from their memory traces to mediate future foraging decisions. PMID:23991154

Internal Representation and Memory Formation of Odor Preference Based on Oscillatory Activities in a Terrestrial Slug

ERIC Educational Resources Information Center

Sekiguchi, Tatsuhiko; Furudate, Hiroyuki; Kimura, Tetsuya

2010-01-01

The terrestrial slug "Limax" exhibits a highly developed ability to learn odors with a small nervous system. When a fluorescent dye, Lucifer Yellow (LY), is injected into the slug's body cavity after odor-taste associative conditioning, a group of neurons in the procerebral (PC) lobe, an olfactory center of the slug, is labeled by LY. We examined…

A spiking neural network model of self-organized pattern recognition in the early mammalian olfactory system.

PubMed

Kaplan, Bernhard A; Lansner, Anders

2014-01-01

Olfactory sensory information passes through several processing stages before an odor percept emerges. The question how the olfactory system learns to create odor representations linking those different levels and how it learns to connect and discriminate between them is largely unresolved. We present a large-scale network model with single and multi-compartmental Hodgkin-Huxley type model neurons representing olfactory receptor neurons (ORNs) in the epithelium, periglomerular cells, mitral/tufted cells and granule cells in the olfactory bulb (OB), and three types of cortical cells in the piriform cortex (PC). Odor patterns are calculated based on affinities between ORNs and odor stimuli derived from physico-chemical descriptors of behaviorally relevant real-world odorants. The properties of ORNs were tuned to show saturated response curves with increasing concentration as seen in experiments. On the level of the OB we explored the possibility of using a fuzzy concentration interval code, which was implemented through dendro-dendritic inhibition leading to winner-take-all like dynamics between mitral/tufted cells belonging to the same glomerulus. The connectivity from mitral/tufted cells to PC neurons was self-organized from a mutual information measure and by using a competitive Hebbian-Bayesian learning algorithm based on the response patterns of mitral/tufted cells to different odors yielding a distributed feed-forward projection to the PC. The PC was implemented as a modular attractor network with a recurrent connectivity that was likewise organized through Hebbian-Bayesian learning. We demonstrate the functionality of the model in a one-sniff-learning and recognition task on a set of 50 odorants. Furthermore, we study its robustness against noise on the receptor level and its ability to perform concentration invariant odor recognition. Moreover, we investigate the pattern completion capabilities of the system and rivalry dynamics for odor mixtures.

A spiking neural network model of self-organized pattern recognition in the early mammalian olfactory system

PubMed Central

Kaplan, Bernhard A.; Lansner, Anders

2014-01-01

Olfactory sensory information passes through several processing stages before an odor percept emerges. The question how the olfactory system learns to create odor representations linking those different levels and how it learns to connect and discriminate between them is largely unresolved. We present a large-scale network model with single and multi-compartmental Hodgkin–Huxley type model neurons representing olfactory receptor neurons (ORNs) in the epithelium, periglomerular cells, mitral/tufted cells and granule cells in the olfactory bulb (OB), and three types of cortical cells in the piriform cortex (PC). Odor patterns are calculated based on affinities between ORNs and odor stimuli derived from physico-chemical descriptors of behaviorally relevant real-world odorants. The properties of ORNs were tuned to show saturated response curves with increasing concentration as seen in experiments. On the level of the OB we explored the possibility of using a fuzzy concentration interval code, which was implemented through dendro-dendritic inhibition leading to winner-take-all like dynamics between mitral/tufted cells belonging to the same glomerulus. The connectivity from mitral/tufted cells to PC neurons was self-organized from a mutual information measure and by using a competitive Hebbian–Bayesian learning algorithm based on the response patterns of mitral/tufted cells to different odors yielding a distributed feed-forward projection to the PC. The PC was implemented as a modular attractor network with a recurrent connectivity that was likewise organized through Hebbian–Bayesian learning. We demonstrate the functionality of the model in a one-sniff-learning and recognition task on a set of 50 odorants. Furthermore, we study its robustness against noise on the receptor level and its ability to perform concentration invariant odor recognition. Moreover, we investigate the pattern completion capabilities of the system and rivalry dynamics for odor mixtures. PMID:24570657

EOL-1, the Homolog of the Mammalian Dom3Z, Regulates Olfactory Learning in C. elegans

PubMed Central

Shen, Yu; Zhang, Jiangwen; Calarco, John A.

2014-01-01

Learning is an essential function of the nervous system. However, our understanding of molecular underpinnings of learning remains incomplete. Here, we characterize a conserved protein EOL-1 that regulates olfactory learning in Caenorhabditis elegans. A recessive allele of eol-1 (enhanced olfactory learning) learns better to adjust its olfactory preference for bacteria foods and eol-1 acts in the URX sensory neurons to regulate learning. The mammalian homolog of EOL-1, Dom3Z, which regulates quality control of pre-mRNAs, can substitute the function of EOL-1 in learning regulation, demonstrating functional conservation between these homologs. Mutating the residues of Dom3Z that are critical for its enzymatic activity, and the equivalent residues in EOL-1, abolishes the function of these proteins in learning. Together, our results provide insights into the function of EOL-1/Dom3Z and suggest that its activity in pre-mRNA quality control is involved in neural plasticity. PMID:25274815

Cross-modal interaction between visual and olfactory learning in Apis cerana.

PubMed

Zhang, Li-Zhen; Zhang, Shao-Wu; Wang, Zi-Long; Yan, Wei-Yu; Zeng, Zhi-Jiang

2014-10-01

The power of the small honeybee brain carrying out behavioral and cognitive tasks has been shown repeatedly to be highly impressive. The present study investigates, for the first time, the cross-modal interaction between visual and olfactory learning in Apis cerana. To explore the role and molecular mechanisms of cross-modal learning in A. cerana, the honeybees were trained and tested in a modified Y-maze with seven visual and five olfactory stimulus, where a robust visual threshold for black/white grating (period of 2.8°-3.8°) and relatively olfactory threshold (concentration of 50-25%) was obtained. Meanwhile, the expression levels of five genes (AcCREB, Acdop1, Acdop2, Acdop3, Actyr1) related to learning and memory were analyzed under different training conditions by real-time RT-PCR. The experimental results indicate that A. cerana could exhibit cross-modal interactions between visual and olfactory learning by reducing the threshold level of the conditioning stimuli, and that these genes may play important roles in the learning process of honeybees.

Adult Mammalian Neurogenesis and Motivated Behaviors.

PubMed

Jorgensen, Claudia

2018-05-31

Adult neurogenesis continues to captivate the curiosity of the scientific community; and researchers seem to have a particular interest in identifying the functional implications of such plasticity. While the majority of research focuses on the association between adult neurogenesis and learning and memory (including spatial learning associated with hippocampal neurogenesis and olfactory discrimination associated with neurogenesis in the olfactory system), the following review will explore the link to motivated behaviors. In particular, goal-directed behaviors such as sociosexual, parental, aggressive, as well as depression- and anxiety-like behaviors and their reciprocal association to adult neurogenesis will be evaluated. The review will detail research in humans and other mammalian species. Furthermore, the potential mechanisms underlying these neurogenic alterations will be highlighted. Lastly, the review will conclude with a discussion on the functional significance of these newly generated cells in mediating goal-directed behaviors. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Odourant dominance in olfactory mixture processing: what makes a strong odourant?

PubMed Central

Schubert, Marco; Sandoz, Jean-Christophe; Galizia, Giovanni; Giurfa, Martin

2015-01-01

The question of how animals process stimulus mixtures remains controversial as opposing views propose that mixtures are processed analytically, as the sum of their elements, or holistically, as unique entities different from their elements. Overshadowing is a widespread phenomenon that can help decide between these alternatives. In overshadowing, an individual trained with a binary mixture learns one element better at the expense of the other. Although element salience (learning success) has been suggested as a main explanation for overshadowing, the mechanisms underlying this phenomenon remain unclear. We studied olfactory overshadowing in honeybees to uncover the mechanisms underlying olfactory-mixture processing. We provide, to our knowledge, the most comprehensive dataset on overshadowing to date based on 90 experimental groups involving more than 2700 bees trained either with six odourants or with their resulting 15 binary mixtures. We found that bees process olfactory mixtures analytically and that salience alone cannot predict overshadowing. After normalizing learning success, we found that an unexpected feature, the generalization profile of an odourant, was determinant for overshadowing. Odourants that induced less generalization enhanced their distinctiveness and became dominant in the mixture. Our study thus uncovers features that determine odourant dominance within olfactory mixtures and allows the referring of this phenomenon to differences in neural activity both at the receptor and the central level in the insect nervous system. PMID:25652840

Association of Amine-Receptor DNA Sequence Variants with Associative Learning in the Honeybee.

PubMed

Lagisz, Malgorzata; Mercer, Alison R; de Mouzon, Charlotte; Santos, Luana L S; Nakagawa, Shinichi

2016-03-01

Octopamine- and dopamine-based neuromodulatory systems play a critical role in learning and learning-related behaviour in insects. To further our understanding of these systems and resulting phenotypes, we quantified DNA sequence variations at six loci coding octopamine-and dopamine-receptors and their association with aversive and appetitive learning traits in a population of honeybees. We identified 79 polymorphic sequence markers (mostly SNPs and a few insertions/deletions) located within or close to six candidate genes. Intriguingly, we found that levels of sequence variation in the protein-coding regions studied were low, indicating that sequence variation in the coding regions of receptor genes critical to learning and memory is strongly selected against. Non-coding and upstream regions of the same genes, however, were less conserved and sequence variations in these regions were weakly associated with between-individual differences in learning-related traits. While these associations do not directly imply a specific molecular mechanism, they suggest that the cross-talk between dopamine and octopamine signalling pathways may influence olfactory learning and memory in the honeybee.

Chemical factors determine olfactory system beta oscillations in waking rats.

PubMed

Lowry, Catherine A; Kay, Leslie M

2007-07-01

Recent studies have pointed to olfactory system beta oscillations of the local field potential (15-30 Hz) and their roles both in learning and as specific responses to predator odors. To describe odorant physical properties, resultant behavioral responses and changes in the central olfactory system that may induce these oscillations without associative learning, we tested rats with 26 monomolecular odorants spanning 6 log units of theoretical vapor pressure (estimate of relative vapor phase concentration) and 10 different odor mixtures. We found odorant vapor phase concentration to be inversely correlated with investigation time on the first presentation, after which investigation times were brief and not different across odorants. Analysis of local field potentials from the olfactory bulb and anterior piriform cortex shows that beta oscillations in waking rats occur specifically in response to the class of volatile organic compounds with vapor pressures of 1-120 mmHg. Beta oscillations develop over the first three to four presentations and are weakly present for some odorants in anesthetized rats. Gamma oscillations show a smaller effect that is not restricted to the same range of odorants. Olfactory bulb theta oscillations were also examined as a measure of effective afferent input strength, and the power of these oscillations did not vary systematically with vapor pressure, suggesting that it is not olfactory bulb drive strength that determines the presence of beta oscillations. Theta band coherence analysis shows that coupling strength between the olfactory bulb and piriform cortex increases linearly with vapor phase concentration, which may facilitate beta oscillations above a threshold.

Olfactory enrichment and scent cue associative learning in captive birds of prey.

PubMed

Nelson Slater, Melissa; Hauber, Mark E

2017-03-01

As the use of enrichment in zoos has become a standardized husbandry practice, the continued improvement of enrichment programs should be concomitant with empirical validation of those practices. The role of scent as enrichment remains an unexplored avenue for many bird species. We conducted a multi-phase experiment to introduce wrapped food packages and scent cuing to indicate food presence into the exhibits of several birds of prey species at the Bronx Zoo, New York City, to assess if scent can function as enrichment in these species. Our research found support for these birds associating a novel scent cue from a package with the presence of food inside. When tested with sham (empty) packages, these individuals more often and more extensively handled scented versus unscented packages. Overall, these results indicate the ability of some our small sample of individuals to learn olfactory cues and provide support for trials to include olfactory enrichment as a potential part of the daily routine for some birds of prey in zoo settings. © 2017 Wiley Periodicals, Inc.

Proteomic Analysis of the Human Olfactory Bulb.

PubMed

Dammalli, Manjunath; Dey, Gourav; Madugundu, Anil K; Kumar, Manish; Rodrigues, Benvil; Gowda, Harsha; Siddaiah, Bychapur Gowrishankar; Mahadevan, Anita; Shankar, Susarla Krishna; Prasad, Thottethodi Subrahmanya Keshava

2017-08-01

The importance of olfaction to human health and disease is often underappreciated. Olfactory dysfunction has been reported in association with a host of common complex diseases, including neurological diseases such as Alzheimer's disease and Parkinson's disease. For health, olfaction or the sense of smell is also important for most mammals, for optimal engagement with their environment. Indeed, animals have developed sophisticated olfactory systems to detect and interpret the rich information presented to them to assist in day-to-day activities such as locating food sources, differentiating food from poisons, identifying mates, promoting reproduction, avoiding predators, and averting death. In this context, the olfactory bulb is a vital component of the olfactory system receiving sensory information from the axons of the olfactory receptor neurons located in the nasal cavity and the first place that processes the olfactory information. We report in this study original observations on the human olfactory bulb proteome in healthy subjects, using a high-resolution mass spectrometry-based proteomic approach. We identified 7750 nonredundant proteins from human olfactory bulbs. Bioinformatics analysis of these proteins showed their involvement in biological processes associated with signal transduction, metabolism, transport, and olfaction. These new observations provide a crucial baseline molecular profile of the human olfactory bulb proteome, and should assist the future discovery of biomarker proteins and novel diagnostics associated with diseases characterized by olfactory dysfunction.

Olfactory Cued Learning Paradigm.

PubMed

Liu, Gary; McClard, Cynthia K; Tepe, Burak; Swanson, Jessica; Pekarek, Brandon; Panneerselvam, Sugi; Arenkiel, Benjamin R

2017-05-05

Sensory stimulation leads to structural changes within the CNS (Central Nervous System), thus providing the fundamental mechanism for learning and memory. The olfactory circuit offers a unique model for studying experience-dependent plasticity, partly due to a continuous supply of integrating adult born neurons. Our lab has recently implemented an olfactory cued learning paradigm in which specific odor pairs are coupled to either a reward or punishment to study downstream circuit changes. The following protocol outlines the basic set up for our learning paradigm. Here, we describe the equipment setup, programming of software, and method of behavioral training.

Matching- and Nonmatching-to-Sample Concept Learning in Rats Using Olfactory Stimuli

ERIC Educational Resources Information Center

April, L. Brooke; Bruce, Katherine; Galizio, Mark

2011-01-01

Previous research has shown that rats can learn matching-to-sample relations with olfactory stimuli; however, the specific characteristics of this relational control are unclear. In Experiment 1, 6 rats were trained to either match or nonmatch to sample in a modified operant chamber using common household spices as olfactory stimuli. After…

A Low Concentration of Ethanol Impairs Learning but Not Motor and Sensory Behavior in Drosophila Larvae

PubMed Central

Ghezzi, Alfredo; Cady, Amanda M.; Najjar, Kristina; Hatch, Michael M.; Shah, Ruchita R.; Bhat, Amar; Hariri, Omar; Haroun, Kareem B.; Young, Melvin C.; Fife, Kathryn; Hooten, Jeff; Tran, Tuan; Goan, Daniel; Desai, Foram; Husain, Farhan; Godinez, Ryan M.; Sun, Jeffrey C.; Corpuz, Jonathan; Moran, Jacxelyn; Zhong, Allen C.; Chen, William Y.; Atkinson, Nigel S.

2012-01-01

Drosophila melanogaster has proven to be a useful model system for the genetic analysis of ethanol-associated behaviors. However, past studies have focused on the response of the adult fly to large, and often sedating, doses of ethanol. The pharmacological effects of low and moderate quantities of ethanol have remained understudied. In this study, we tested the acute effects of low doses of ethanol (∼7 mM internal concentration) on Drosophila larvae. While ethanol did not affect locomotion or the response to an odorant, we observed that ethanol impaired associative olfactory learning when the heat shock unconditioned stimulus (US) intensity was low but not when the heat shock US intensity was high. We determined that the reduction in learning at low US intensity was not a result of ethanol anesthesia since ethanol-treated larvae responded to the heat shock in the same manner as untreated animals. Instead, low doses of ethanol likely impair the neuronal plasticity that underlies olfactory associative learning. This impairment in learning was reversible indicating that exposure to low doses of ethanol does not leave any long lasting behavioral or physiological effects. PMID:22624024

EOL-1, the homolog of the mammalian Dom3Z, regulates olfactory learning in C. elegans.

PubMed

Shen, Yu; Zhang, Jiangwen; Calarco, John A; Zhang, Yun

2014-10-01

Learning is an essential function of the nervous system. However, our understanding of molecular underpinnings of learning remains incomplete. Here, we characterize a conserved protein EOL-1 that regulates olfactory learning in Caenorhabditis elegans. A recessive allele of eol-1 (enhanced olfactory learning) learns better to adjust its olfactory preference for bacteria foods and eol-1 acts in the URX sensory neurons to regulate learning. The mammalian homolog of EOL-1, Dom3Z, which regulates quality control of pre-mRNAs, can substitute the function of EOL-1 in learning regulation, demonstrating functional conservation between these homologs. Mutating the residues of Dom3Z that are critical for its enzymatic activity, and the equivalent residues in EOL-1, abolishes the function of these proteins in learning. Together, our results provide insights into the function of EOL-1/Dom3Z and suggest that its activity in pre-mRNA quality control is involved in neural plasticity. Copyright © 2014 the authors 0270-6474/14/3413364-07$15.00/0.

A Fully Automated Drosophila Olfactory Classical Conditioning and Testing System for Behavioral Learning and Memory Assessment

PubMed Central

Jiang, Hui; Hanna, Eriny; Gatto, Cheryl L.; Page, Terry L.; Bhuva, Bharat; Broadie, Kendal

2016-01-01

Background Aversive olfactory classical conditioning has been the standard method to assess Drosophila learning and memory behavior for decades, yet training and testing are conducted manually under exceedingly labor-intensive conditions. To overcome this severe limitation, a fully automated, inexpensive system has been developed, which allows accurate and efficient Pavlovian associative learning/memory analyses for high-throughput pharmacological and genetic studies. New Method The automated system employs a linear actuator coupled to an odorant T-maze with airflow-mediated transfer of animals between training and testing stages. Odorant, airflow and electrical shock delivery are automatically administered and monitored during training trials. Control software allows operator-input variables to define parameters of Drosophila learning, short-term memory and long-term memory assays. Results The approach allows accurate learning/memory determinations with operational fail-safes. Automated learning indices (immediately post-training) and memory indices (after 24 hours) are comparable to traditional manual experiments, while minimizing experimenter involvement. Comparison with Existing Methods The automated system provides vast improvements over labor-intensive manual approaches with no experimenter involvement required during either training or testing phases. It provides quality control tracking of airflow rates, odorant delivery and electrical shock treatments, and an expanded platform for high-throughput studies of combinational drug tests and genetic screens. The design uses inexpensive hardware and software for a total cost of ~$500US, making it affordable to a wide range of investigators. Conclusions This study demonstrates the design, construction and testing of a fully automated Drosophila olfactory classical association apparatus to provide low-labor, high-fidelity, quality-monitored, high-throughput and inexpensive learning and memory behavioral assays. PMID:26703418

A fully automated Drosophila olfactory classical conditioning and testing system for behavioral learning and memory assessment.

PubMed

Jiang, Hui; Hanna, Eriny; Gatto, Cheryl L; Page, Terry L; Bhuva, Bharat; Broadie, Kendal

2016-03-01

Aversive olfactory classical conditioning has been the standard method to assess Drosophila learning and memory behavior for decades, yet training and testing are conducted manually under exceedingly labor-intensive conditions. To overcome this severe limitation, a fully automated, inexpensive system has been developed, which allows accurate and efficient Pavlovian associative learning/memory analyses for high-throughput pharmacological and genetic studies. The automated system employs a linear actuator coupled to an odorant T-maze with airflow-mediated transfer of animals between training and testing stages. Odorant, airflow and electrical shock delivery are automatically administered and monitored during training trials. Control software allows operator-input variables to define parameters of Drosophila learning, short-term memory and long-term memory assays. The approach allows accurate learning/memory determinations with operational fail-safes. Automated learning indices (immediately post-training) and memory indices (after 24h) are comparable to traditional manual experiments, while minimizing experimenter involvement. The automated system provides vast improvements over labor-intensive manual approaches with no experimenter involvement required during either training or testing phases. It provides quality control tracking of airflow rates, odorant delivery and electrical shock treatments, and an expanded platform for high-throughput studies of combinational drug tests and genetic screens. The design uses inexpensive hardware and software for a total cost of ∼$500US, making it affordable to a wide range of investigators. This study demonstrates the design, construction and testing of a fully automated Drosophila olfactory classical association apparatus to provide low-labor, high-fidelity, quality-monitored, high-throughput and inexpensive learning and memory behavioral assays. Copyright © 2015 Elsevier B.V. All rights reserved.

Exercise Is Associated with Lower Long-Term Risk of Olfactory Impairment in Older Adults

PubMed Central

Schubert, Carla R.; Cruickshanks, Karen J.; Nondahl, David M.; Klein, Barbara EK; Klein, Ronald; Fischer, Mary E.

2013-01-01

Importance The prevalence of olfactory impairment is high in older adults and this decline in olfactory ability may pose health and safety risks, affect nutrition and decrease quality of life. It is important to identify modifiable risk factors to reduce the burden of olfactory impairment in aging populations. Objectives To determine if exercise is associated with the 10-year cumulative incidence of olfactory impairment. Design, Setting and Participants Observational longitudinal population-based Epidemiology of Hearing Loss Study. Participants without olfactory impairment (n=1611) were ages 53-97 years at baseline and were followed for up to ten years (1998-2010). Interventions None Main Outcome and Measures Olfaction was measured with the San Diego Odor Identification Test at three examinations (1998-2000, 2003-2005, 2009-2010) of the Epidemiology of Hearing Loss Study. The main outcome was the incidence of olfactory impairment five (2003-2005) or ten (2009-2010) years later and the association of baseline exercise with the long-term risk of developing olfactory impairment. Results The 10-year cumulative incidence of olfactory impairment was 27.6% (95% confidence interval =25.3, 29.9) and rates varied by age and sex; those who were older (Hazard Ratio =1.88, 95% Confidence Interval=1.74, 2.03, for every 5 years) or male (Hazard Ratio=1.27, 95% Confidence Interval=1.00, 1.61) had an increased risk of olfactory impairment. Participants who reported exercising at least once a week long enough to work up a sweat had a decreased risk of olfactory impairment (age and sex adjusted Hazard Ratio= 0.76, 95% CI= 0.60, 0.97). Increasing frequency of exercise was associated with decreasing risk of developing olfactory impairment (p for trend = 0.02). Conclusion and Relevance Regular exercise was associated with lower 10-year cumulative incidence of olfactory impairment. Older adults who exercise may be able to retain olfactory function with age. PMID:24135745

[Clinical assessment of olfactory performance - why patient interviews are not enough : A report on lessons learned in planning studies with anosmic patients].

PubMed

Schöpf, V; Kollndorfer, K

2015-07-01

Olfactory dysfunction and loss of smell are mostly associated with an immense decrease in the quality of life. The aim of the presented study was to report on particularities in the acquisition of patients with olfactory dysfunction. During July 2011 and May 2014 we were contacted by 300 potential patients with self-reported loss of smell, 95 (54 female, 41 male, mean age 53) of which were invited for clinical testing after phone interviews. Clinical smell testing revealed 46 patients with anosmia, 38 with hyposmia, and 11 with normosmia. Self-assessment of olfactory function only correlated with clinical scores if patients had nearly no olfactory function left. The ability of self-assessment of olfactory function was independent of age or sex. Further, most patients were not able to report on the reason for or the duration of their olfactory dysfunction. Our report shows that patients with olfactory dysfunction are hardly ever ably to assess their grade of performance reduction. Awareness among patients with a reduced sense of smell is of great general importance, since it can be an indicator of neurodegenerative diseases. This should especially be noted for patients older than 50 who are not able to indicate a reason for their loss of smell.

The orexin component of fasting triggers memory processes underlying conditioned food selection in the rat.

PubMed

Ferry, Barbara; Duchamp-Viret, Patricia

2014-03-14

To test the selectivity of the orexin A (OXA) system in olfactory sensitivity, the present study compared the effects of fasting and of central infusion of OXA on the memory processes underlying odor-malaise association during the conditioned odor aversion (COA) paradigm. Animals implanted with a cannula in the left ventricle received ICV infusion of OXA or artificial cerebrospinal fluid (ACSF) 1 h before COA acquisition. An additional group of intact rats were food-deprived for 24 h before acquisition. Results showed that the increased olfactory sensitivity induced by fasting and by OXA infusion was accompanied by enhanced COA performance. The present results suggest that fasting-induced central OXA release influenced COA learning by increasing not only olfactory sensitivity, but also the memory processes underlying the odor-malaise association.

The orexin component of fasting triggers memory processes underlying conditioned food selection in the rat

PubMed Central

Ferry, Barbara; Duchamp-Viret, Patricia

2014-01-01

To test the selectivity of the orexin A (OXA) system in olfactory sensitivity, the present study compared the effects of fasting and of central infusion of OXA on the memory processes underlying odor–malaise association during the conditioned odor aversion (COA) paradigm. Animals implanted with a cannula in the left ventricle received ICV infusion of OXA or artificial cerebrospinal fluid (ACSF) 1 h before COA acquisition. An additional group of intact rats were food-deprived for 24 h before acquisition. Results showed that the increased olfactory sensitivity induced by fasting and by OXA infusion was accompanied by enhanced COA performance. The present results suggest that fasting-induced central OXA release influenced COA learning by increasing not only olfactory sensitivity, but also the memory processes underlying the odor–malaise association. PMID:24634353

Visual Associative Learning in Restrained Honey Bees with Intact Antennae

PubMed Central

Dobrin, Scott E.; Fahrbach, Susan E.

2012-01-01

A restrained honey bee can be trained to extend its proboscis in response to the pairing of an odor with a sucrose reward, a form of olfactory associative learning referred to as the proboscis extension response (PER). Although the ability of flying honey bees to respond to visual cues is well-established, associative visual learning in restrained honey bees has been challenging to demonstrate. Those few groups that have documented vision-based PER have reported that removing the antennae prior to training is a prerequisite for learning. Here we report, for a simple visual learning task, the first successful performance by restrained honey bees with intact antennae. Honey bee foragers were trained on a differential visual association task by pairing the presentation of a blue light with a sucrose reward and leaving the presentation of a green light unrewarded. A negative correlation was found between age of foragers and their performance in the visual PER task. Using the adaptations to the traditional PER task outlined here, future studies can exploit pharmacological and physiological techniques to explore the neural circuit basis of visual learning in the honey bee. PMID:22701575

Chronically Increased G[subscript s][alpha] Signaling Disrupts Associative and Spatial Learning

ERIC Educational Resources Information Center

Bourtchouladze, Rusiko; Patterson, Susan L.; Kelly, Michele P.; Kreibich, Arati; Kandel, Eric R.; Abel, Ted

2006-01-01

The cAMP/PKA pathway plays a critical role in learning and memory systems in animals ranging from mice to "Drosophila" to "Aplysia." Studies of olfactory learning in "Drosophila" suggest that altered expression of either positive or negative regulators of the cAMP/PKA signaling pathway beyond a certain optimum range may be deleterious. Here we…

Neural Correlates of Olfactory Learning: Critical Role of Centrifugal Neuromodulation

ERIC Educational Resources Information Center

Fletcher, Max L.; Chen, Wei R.

2010-01-01

The mammalian olfactory system is well established for its remarkable capability of undergoing experience-dependent plasticity. Although this process involves changes at multiple stages throughout the central olfactory pathway, even the early stages of processing, such as the olfactory bulb and piriform cortex, can display a high degree of…

Olfactory discrimination ability and brain expression of c-fos, Gir and Glut1 mRNA are altered in n-3 fatty acid-depleted rats.

PubMed

Hichami, Aziz; Datiche, Frédérique; Ullah, Sana; Liénard, Fabienne; Chardigny, Jean-Michel; Cattarelli, Martine; Khan, Naim Akhtar

2007-11-22

The long-chain polyunsaturated n-3 fatty acids (n-3 PUFA), particularly docosahexaenoic acid (DHA), are abundantly present in the central nervous system and play an important role in cognitive functions such as learning and memory. We, therefore, investigated the effects of n-3 PUFA-depletion in rats (F2 generation) on the learning of an olfactory discrimination task, progressively acquired within a four-arm maze, and on the mRNA expression of some candidate genes, i.e., c-fos, Gir and glucose transporter (Glut1), which could reflect the level of cerebral activity. We observed that DHA contents were dramatically decreased in the olfactory bulb, the piriform cortex and the neocortex of n-3-depleted rats. Furthermore, the n-3 deficiency resulted in a mild olfactory learning impairment as these rats required more days to master the olfactory task compared to control rats. Real-time RT-PCR experiments revealed that the training induced the expression of c-fos mRNA in all the three regions of the brain whereas Gir and Glut1 mRNA were induced only in olfactory bulb and neocortex. However, such an increase was less marked in the n-3-deficient rats. Taken together, these results allow us to assume that the behavioural impairment in n-3-deficient rats is linked to the depletion of n-3 fatty acids in brain regions processing olfactory cues. Data are discussed in view of the possible role of some of these genes in learning-induced neuronal olfactory plasticity.

Anatomy and behavioral function of serotonin receptors in Drosophila melanogaster larvae.

PubMed

Huser, Annina; Eschment, Melanie; Güllü, Nazli; Collins, Katharina A N; Böpple, Kathrin; Pankevych, Lyubov; Rolsing, Emilia; Thum, Andreas S

2017-01-01

The biogenic amine serotonin (5-HT) is an important neuroactive molecule in the central nervous system of the majority of animal phyla. 5-HT binds to specific G protein-coupled and ligand-gated ion receptors to regulate particular aspects of animal behavior. In Drosophila, as in many other insects this includes the regulation of locomotion and feeding. Due to its genetic amenability and neuronal simplicity the Drosophila larva has turned into a useful model for studying the anatomical and molecular basis of chemosensory behaviors. This is particularly true for the olfactory system, which is mostly described down to the synaptic level over the first three orders of neuronal information processing. Here we focus on the 5-HT receptor system of the Drosophila larva. In a bipartite approach consisting of anatomical and behavioral experiments we describe the distribution and the implications of individual 5-HT receptors on naïve and acquired chemosensory behaviors. Our data suggest that 5-HT1A, 5-HT1B, and 5-HT7 are dispensable for larval naïve olfactory and gustatory choice behaviors as well as for appetitive and aversive associative olfactory learning and memory. In contrast, we show that 5-HT/5-HT2A signaling throughout development, but not as an acute neuronal function, affects associative olfactory learning and memory using high salt concentration as a negative unconditioned stimulus. These findings describe for the first time an involvement of 5-HT signaling in learning and memory in Drosophila larvae. In the longer run these results may uncover developmental, 5-HT dependent principles related to reinforcement processing possibly shared with adult Drosophila and other insects.

Anatomy and behavioral function of serotonin receptors in Drosophila melanogaster larvae

PubMed Central

Huser, Annina; Eschment, Melanie; Güllü, Nazli; Collins, Katharina A. N.; Böpple, Kathrin; Pankevych, Lyubov; Rolsing, Emilia; Thum, Andreas S.

2017-01-01

The biogenic amine serotonin (5-HT) is an important neuroactive molecule in the central nervous system of the majority of animal phyla. 5-HT binds to specific G protein-coupled and ligand-gated ion receptors to regulate particular aspects of animal behavior. In Drosophila, as in many other insects this includes the regulation of locomotion and feeding. Due to its genetic amenability and neuronal simplicity the Drosophila larva has turned into a useful model for studying the anatomical and molecular basis of chemosensory behaviors. This is particularly true for the olfactory system, which is mostly described down to the synaptic level over the first three orders of neuronal information processing. Here we focus on the 5-HT receptor system of the Drosophila larva. In a bipartite approach consisting of anatomical and behavioral experiments we describe the distribution and the implications of individual 5-HT receptors on naïve and acquired chemosensory behaviors. Our data suggest that 5-HT1A, 5-HT1B, and 5-HT7 are dispensable for larval naïve olfactory and gustatory choice behaviors as well as for appetitive and aversive associative olfactory learning and memory. In contrast, we show that 5-HT/5-HT2A signaling throughout development, but not as an acute neuronal function, affects associative olfactory learning and memory using high salt concentration as a negative unconditioned stimulus. These findings describe for the first time an involvement of 5-HT signaling in learning and memory in Drosophila larvae. In the longer run these results may uncover developmental, 5-HT dependent principles related to reinforcement processing possibly shared with adult Drosophila and other insects. PMID:28777821

A neonicotinoid impairs olfactory learning in Asian honey bees (Apis cerana) exposed as larvae or as adults

PubMed Central

Tan, Ken; Chen, Weiwen; Dong, Shihao; Liu, Xiwen; Wang, Yuchong; Nieh, James C.

2015-01-01

Xenobiotics such as the neonicotinoid pesticide, imidacloprid, are used globally, but their effects on native bee species are poorly understood. We studied the effects of sublethal doses of imidacloprid on olfactory learning in the native honey bee species, Apis cerana, an important pollinator of agricultural and native plants throughout Asia. We provide the first evidence that imidacloprid can impair learning in A. cerana workers exposed as adults or as larvae. Adults that ingested a single imidacloprid dose as low as 0.1 ng/bee had significantly reduced olfactory learning acquisition, which was 1.6-fold higher in control bees. Longer-term learning (1-17 h after the last learning trial) was also impaired. Bees exposed as larvae to a total dose of 0.24 ng/bee did not have reduced survival to adulthood. However, these larval-treated bees had significantly impaired olfactory learning when tested as adults: control bees exhibited up to 4.8-fold better short-term learning acquisition, though longer-term learning was not affected. Thus, sublethal cognitive deficits elicited by neonicotinoids on a broad range of native bee species deserve further study. PMID:26086769

Synthesizing Neurophysiology, Genetics, Behaviour and Learning to Produce Whole-Insect Programmable Sensors to Detect Volatile Chemicals.

USDA-ARS?s Scientific Manuscript database

Most insects have evolved highly sensitive olfactory systems which respond to odors in their environment. The extremely sensitive nature of the insect olfaction system is enhanced by the ability to learn to associate external stimuli with resources, such as food, hosts, and mates. There have been a ...

Aversive Olfactory Learning and Associative Long-Term Memory in "Caenorhabditis elegans"

ERIC Educational Resources Information Center

Amano, Hisayuki; Maruyama, Ichiro N.

2011-01-01

The nematode "Caenorhabditis elegans" ("C. elegans") adult hermaphrodite has 302 invariant neurons and is suited for cellular and molecular studies on complex behaviors including learning and memory. Here, we have developed protocols for classical conditioning of worms with 1-propanol, as a conditioned stimulus (CS), and hydrochloride (HCl) (pH…

Biological complexity and adaptability of simple mammalian olfactory memory systems.

PubMed

Brennan, P; Keverne, E B

2015-03-01

Chemosensory systems play vital roles in the lives of most mammals, including the detection and identification of predators, as well as sex and reproductive status and the identification of individual conspecifics. All of these capabilities require a process of recognition involving a combination of innate (kairomonal/pheromonal) and learned responses. Across very different phylogenies, the mechanisms for pheromonal and odour learning have much in common. They are frequently associated with plasticity of GABA-ergic feedback at the initial level of processing the chemosensory information, which enhances its pattern separation capability. Association of odourant features into an odour object primarily involves anterior piriform cortex for non-social odours. However, the medial amygdala appears to be involved in both the recognition of social odours and their association with chemosensory information sensed by the vomeronasal system. Unusually not only the sensory neurons themselves, but also the GABA-ergic interneurons in the olfactory bulb are continually being replaced, with implications for the induction and maintenance of learned chemosensory responses. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Olfactory memory in the old and very old: relations to episodic and semantic memory and APOE genotype.

PubMed

Larsson, Maria; Hedner, Margareta; Papenberg, Goran; Seubert, Janina; Bäckman, Lars; Laukka, Erika J

2016-02-01

The neuroanatomical organization that underlies olfactory memory is different from that of other memory types. The present work examines olfactory memory in an elderly population-based sample (Swedish National Study on Aging and Care in Kungsholmen) aged 60-100 years (n = 2280). We used structural equation modeling to investigate whether olfactory memory in old age is best conceptualized as a distinct category, differentiated from episodic and semantic memory. Further, potential olfactory dedifferentiation and genetic associations (APOE) to olfactory function in late senescence were investigated. Results are in support of a 3-factor solution where olfactory memory, as indexed by episodic odor recognition and odor identification, is modeled separately from episodic and semantic memory for visual and verbal information. Increasing age was associated with poorer olfactory memory performance, and observed age-related deficits were further exacerbated for carriers of the APOE ε4 allele; these effects tended to be larger for olfactory memory compared to episodic and semantic memory pertaining to other sensory systems (vision, auditory). Finally, stronger correlations between olfactory and episodic memory, indicating dedifferentiation, were observed in the older age groups. Copyright © 2016 Elsevier Inc. All rights reserved.

Olfactory discrimination predicts cognitive decline among community-dwelling older adults

PubMed Central

Sohrabi, H R; Bates, K A; Weinborn, M G; Johnston, A N B; Bahramian, A; Taddei, K; Laws, S M; Rodrigues, M; Morici, M; Howard, M; Martins, G; Mackay-Sim, A; Gandy, S E; Martins, R N

2012-01-01

The presence of olfactory dysfunction in individuals at higher risk of Alzheimer's disease has significant diagnostic and screening implications for preventive and ameliorative drug trials. Olfactory threshold, discrimination and identification can be reliably recorded in the early stages of neurodegenerative diseases. The current study has examined the ability of various olfactory functions in predicting cognitive decline in a community-dwelling sample. A group of 308 participants, aged 46–86 years old, were recruited for this study. After 3 years of follow-up, participants were divided into cognitively declined and non-declined groups based on their performance on a neuropsychological battery. Assessment of olfactory functions using the Sniffin' Sticks battery indicated that, contrary to previous findings, olfactory discrimination, but not olfactory identification, significantly predicted subsequent cognitive decline (odds ratio=0.869; P<0.05; 95% confidence interval=0.764−0.988). The current study findings confirm previously reported associations between olfactory and cognitive functions, and indicate that impairment in olfactory discrimination can predict future cognitive decline. These findings further our current understanding of the association between cognition and olfaction, and support olfactory assessment in screening those at higher risk of dementia. PMID:22832962

Olfactory discrimination predicts cognitive decline among community-dwelling older adults.

PubMed

Sohrabi, H R; Bates, K A; Weinborn, M G; Johnston, A N B; Bahramian, A; Taddei, K; Laws, S M; Rodrigues, M; Morici, M; Howard, M; Martins, G; Mackay-Sim, A; Gandy, S E; Martins, R N

2012-05-22

The presence of olfactory dysfunction in individuals at higher risk of Alzheimer's disease has significant diagnostic and screening implications for preventive and ameliorative drug trials. Olfactory threshold, discrimination and identification can be reliably recorded in the early stages of neurodegenerative diseases. The current study has examined the ability of various olfactory functions in predicting cognitive decline in a community-dwelling sample. A group of 308 participants, aged 46-86 years old, were recruited for this study. After 3 years of follow-up, participants were divided into cognitively declined and non-declined groups based on their performance on a neuropsychological battery. Assessment of olfactory functions using the Sniffin' Sticks battery indicated that, contrary to previous findings, olfactory discrimination, but not olfactory identification, significantly predicted subsequent cognitive decline (odds ratio = 0.869; P<0.05; 95% confidence interval = 0.764-0.988). The current study findings confirm previously reported associations between olfactory and cognitive functions, and indicate that impairment in olfactory discrimination can predict future cognitive decline. These findings further our current understanding of the association between cognition and olfaction, and support olfactory assessment in screening those at higher risk of dementia.

Olfactory Function is Associated with Cognitive Performance: Results of the Heinz Nixdorf Recall Study.

PubMed

Tebrügge, Sarah; Winkler, Angela; Gerards, Diana; Weimar, Christian; Moebus, Susanne; Jöckel, Karl-Heinz; Erbel, Raimund; Jokisch, Martha

2018-01-01

There is strong evidence for an association of olfactory dysfunction and neurodegenerative diseases. Studies on the association of olfaction and cognition in the general population are rare. To evaluate gender- and age-specific associations of olfactory function and cognitive performance in a well characterized population-based study sample. At the third examination of the Heinz Nixdorf Recall study (n = 3,087), 2,640 participants (48% men; 68.2±7.2 years) underwent Sniffin' Sticks Screening Test measuring olfactory function on a scale of 0-12 points. Olfactory function was rated as anosmic, hyposmic, or normosmic (≤6, 7-10 or ≥11 points, respectively). All participants performed eight validated cognitive subtests. Age- (55-64 years, 65-74 years, 75-86 years) and gender-stratified multivariate analysis of covariance was used to evaluate group differences in cognitive performance. Women showed better olfactory function than men (p < 0.001). For middle-aged participants, olfactory groups differed in almost all cognitive subtests. The analyses revealed no gender effects, although associations were slightly greater for women than for men. Anosmics showed the worst cognitive performance and normosmics showed the best cognitive performance. In the young- and old-aged groups, a quantitative association was found for anosmics in all subtests and for normosmics and hyposmics in almost all subtests. This is the first study reporting on age-specific associations of olfactory function and cognitive performance in the general population. The association found in middle-aged participants (65-74 years) may serve as a marker to improve identification of persons at high risk for cognitive decline and dementia.

Neuronal pattern separation in the olfactory bulb improves odor discrimination learning

PubMed Central

Lagier, Samuel; Begnaud, Frédéric; Rodriguez, Ivan; Carleton, Alan

2015-01-01

Neuronal pattern separation is thought to enable the brain to disambiguate sensory stimuli with overlapping features thereby extracting valuable information. In the olfactory system, it remains unknown whether pattern separation acts as a driving force for sensory discrimination and the learning thereof. Here we show that overlapping odor-evoked input patterns to the mouse olfactory bulb (OB) are dynamically reformatted in the network at the timescale of a single breath, giving rise to separated patterns of activity in ensemble of output neurons (mitral/tufted cells; M/T). Strikingly, the extent of pattern separation in M/T assemblies predicts behavioral discrimination performance during the learning phase. Furthermore, exciting or inhibiting GABAergic OB interneurons, using optogenetics or pharmacogenetics, altered pattern separation and thereby odor discrimination learning in a bidirectional way. In conclusion, we propose that the OB network can act as a pattern separator facilitating olfactory stimuli distinction, a process that is sculpted by synaptic inhibition. PMID:26301325

Neuronal pattern separation in the olfactory bulb improves odor discrimination learning.

PubMed

Gschwend, Olivier; Abraham, Nixon M; Lagier, Samuel; Begnaud, Frédéric; Rodriguez, Ivan; Carleton, Alan

2015-10-01

Neuronal pattern separation is thought to enable the brain to disambiguate sensory stimuli with overlapping features, thereby extracting valuable information. In the olfactory system, it remains unknown whether pattern separation acts as a driving force for sensory discrimination and the learning thereof. We found that overlapping odor-evoked input patterns to the mouse olfactory bulb (OB) were dynamically reformatted in the network on the timescale of a single breath, giving rise to separated patterns of activity in an ensemble of output neurons, mitral/tufted (M/T) cells. Notably, the extent of pattern separation in M/T assemblies predicted behavioral discrimination performance during the learning phase. Furthermore, exciting or inhibiting GABAergic OB interneurons, using optogenetics or pharmacogenetics, altered pattern separation and thereby odor discrimination learning in a bidirectional way. In conclusion, we propose that the OB network can act as a pattern separator facilitating olfactory stimulus distinction, a process that is sculpted by synaptic inhibition.

Rapid learning dynamics in individual honeybees during classical conditioning.

PubMed

Pamir, Evren; Szyszka, Paul; Scheiner, Ricarda; Nawrot, Martin P

2014-01-01

Associative learning in insects has been studied extensively by a multitude of classical conditioning protocols. However, so far little emphasis has been put on the dynamics of learning in individuals. The honeybee is a well-established animal model for learning and memory. We here studied associative learning as expressed in individual behavior based on a large collection of data on olfactory classical conditioning (25 datasets, 3298 animals). We show that the group-averaged learning curve and memory retention score confound three attributes of individual learning: the ability or inability to learn a given task, the generally fast acquisition of a conditioned response (CR) in learners, and the high stability of the CR during consecutive training and memory retention trials. We reassessed the prevailing view that more training results in better memory performance and found that 24 h memory retention can be indistinguishable after single-trial and multiple-trial conditioning in individuals. We explain how inter-individual differences in learning can be accommodated within the Rescorla-Wagner theory of associative learning. In both data-analysis and modeling we demonstrate how the conflict between population-level and single-animal perspectives on learning and memory can be disentangled.

Rapid learning dynamics in individual honeybees during classical conditioning

PubMed Central

Pamir, Evren; Szyszka, Paul; Scheiner, Ricarda; Nawrot, Martin P.

2014-01-01

Associative learning in insects has been studied extensively by a multitude of classical conditioning protocols. However, so far little emphasis has been put on the dynamics of learning in individuals. The honeybee is a well-established animal model for learning and memory. We here studied associative learning as expressed in individual behavior based on a large collection of data on olfactory classical conditioning (25 datasets, 3298 animals). We show that the group-averaged learning curve and memory retention score confound three attributes of individual learning: the ability or inability to learn a given task, the generally fast acquisition of a conditioned response (CR) in learners, and the high stability of the CR during consecutive training and memory retention trials. We reassessed the prevailing view that more training results in better memory performance and found that 24 h memory retention can be indistinguishable after single-trial and multiple-trial conditioning in individuals. We explain how inter-individual differences in learning can be accommodated within the Rescorla–Wagner theory of associative learning. In both data-analysis and modeling we demonstrate how the conflict between population-level and single-animal perspectives on learning and memory can be disentangled. PMID:25309366

Olfactory Fear Conditioning Induces Field Potential Potentiation in Rat Olfactory Cortex and Amygdala

ERIC Educational Resources Information Center

Messaoudi, Belkacem; Granjon, Lionel; Mouly, Anne-Marie; Sevelinges, Yannick; Gervais, Remi

2004-01-01

The widely used Pavlovian fear-conditioning paradigms used for studying the neurobiology of learning and memory have mainly used auditory cues as conditioned stimuli (CS). The present work assessed the neural network involved in olfactory fear conditioning, using olfactory bulb stimulation-induced field potential signal (EFP) as a marker of…

Role of olfaction in the foraging behavior and trial-and-error learning in short-nosed fruit bat, Cynopterus sphinx.

PubMed

Zhang, Wei; Zhu, Guangjian; Tan, Liangjing; Yang, Jian; Chen, Yi; Liu, Qi; Shen, Qiqi; Chen, Jinping; Zhang, Libiao

2014-03-01

We observed the foraging behavior of short-nosed fruit bats, Cynopterus sphinx, in captivity. The role of olfaction in their foraging behavior was examined using real fruit, mimetic fruit, and mimetic fruit soaked in the juice of real fruit. The results showed that C. sphinx visited the real fruit more often than the mimetic fruit, but they had no preference between real fruit and treated mimetic fruit. Our experiment indicates that this bat has the ability to find and identify fruit by olfaction. We also tested for behavior of trial-and-error learning. Our observations revealed that the bats could form a sensory memory of the olfactory cue (cedar wood oil) after five days of training because they responded to the olfactory cues. Our results provide the evidence that C. sphinx can establish the connection between the fruit and a non-natural odor through learning and memory with the assistance of olfaction, and can thus recognize a variety of odors by trial-and-error learning. This behavioral flexibility based on olfactory cues will be beneficial for the short-nosed fruit bat in foraging. Copyright © 2013 Elsevier B.V. All rights reserved.

Olfactory Bulb [alpha][subscript 2]-Adrenoceptor Activation Promotes Rat Pup Odor-Preference Learning via a cAMP-Independent Mechanism

ERIC Educational Resources Information Center

Shakhawat, Amin MD.; Harley, Carolyn W.; Yuan, Qi

2012-01-01

In this study, three lines of evidence suggest a role for [alpha][subscript 2]-adrenoreceptors in rat pup odor-preference learning: olfactory bulb infusions of the [alpha][subscript 2]-antagonist, yohimbine, prevents learning; the [alpha][subscript 2]-agonist, clonidine, paired with odor, induces learning; and subthreshold clonidine paired with…

Hypnotherapeutic olfactory conditioning (HOC): case studies of needle phobia, panic disorder, and combat-induced PTSD.

PubMed

Abramowitz, Eitan G; Lichtenberg, Pesach

2009-04-01

The authors developed a technique, which they call hypnotherapeutic olfactory conditioning (HOC), for exploiting the ability of scents to arouse potent emotional reactions. During hypnosis, the patient learns to associate pleasant scents with a sense of security and self-control. The patient can subsequently use this newfound association to overcome phobias and prevent panic attacks. This may be especially effective for posttraumatic stress disorder (PTSD) with episodes of anxiety, flashbacks, and dissociation triggered by smells. The authors present 3 cases, patients with needle phobia, panic disorder, and combat-induced PTSD who were successfully treated with the HOC technique.

Inhibiting DNA methylation alters olfactory extinction but not acquisition learning in Apis cerana and Apis mellifera.

PubMed

Gong, Zhiwen; Wang, Chao; Nieh, James C; Tan, Ken

2016-07-01

DNA methylation plays a key role in invertebrate acquisition and extinction memory. Honey bees have excellent olfactory learning, but the role of DNA methylation in memory formation has, to date, only been studied in Apis mellifera. We inhibited DNA methylation by inhibiting DNA methyltransferase (DNMT) with zebularine (zeb) and studied the resulting effects upon olfactory acquisition and extinction memory in two honey bee species, Apis cerana and A. mellifera. We used the proboscis extension reflex (PER) assay to measure memory. We provide the first demonstration that DNA methylation is also important in the olfactory extinction learning of A. cerana. DNMT did not reduce acquisition learning in either species. However, zeb bidirectionally and differentially altered extinction learning in both species. In particular, zeb provided 1h before acquisition learning improved extinction memory retention in A. mellifera, but reduced extinction memory retention in A. cerana. The reasons for these differences are unclear, but provide a basis for future studies to explore species-specific differences in the effects of methylation on memory formation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Learning about natural variation of odor mixtures enhances categorization in early olfactory processing.

PubMed

Locatelli, Fernando F; Fernandez, Patricia C; Smith, Brian H

2016-09-01

Natural odors are typically mixtures of several chemical components. Mixtures vary in composition among odor objects that have the same meaning. Therefore a central 'categorization' problem for an animal as it makes decisions about odors in natural contexts is to correctly identify odor variants that have the same meaning and avoid variants that have a different meaning. We propose that identified mechanisms of associative and non-associative plasticity in early sensory processing in the insect antennal lobe and mammalian olfactory bulb are central to solving this problem. Accordingly, this plasticity should work to improve categorization of odors that have the opposite meanings in relation to important events. Using synthetic mixtures designed to mimic natural odor variation among flowers, we studied how honey bees learn about and generalize among floral odors associated with food. We behaviorally conditioned honey bees on a difficult odor discrimination problem using synthetic mixtures that mimic natural variation among snapdragon flowers. We then used calcium imaging to measure responses of projection neurons of the antennal lobe, which is the first synaptic relay of olfactory sensory information in the brain, to study how ensembles of projection neurons change as a result of behavioral conditioning. We show how these ensembles become 'tuned' through plasticity to improve categorization of odors that have the different meanings. We argue that this tuning allows more efficient use of the immense coding space of the antennal lobe and olfactory bulb to solve the categorization problem. Our data point to the need for a better understanding of the 'statistics' of the odor space. © 2016. Published by The Company of Biologists Ltd.

Norepinephrine and Learning-Induced Plasticity in Infant Rat Olfactory System

PubMed Central

Sullivan, Regina M.; Wilson, Donald A.; Leon, Michael

2007-01-01

Postnatal olfactory learning produces both a conditioned behavioral response and a modified olfactory bulb neural response to the learned odor. The present report describes the role of norepinephrine (NE) on both of these learned responses in neonatal rat pups. Pups received olfactory classical conditioning training from postnatal days (PN) 1-18. Training consisted of 18 trials with an intertrial interval of 24 hr. For the experimental group, a trial consisted of a pairing of unconditioned stimulus (UCS, stroking/tactile stimulation) and the conditioned stimulus (CS, odor). Control groups received either only the CS (Odor only) or only the UCS (Stroke only). Within each training condition, pups were injected with either the NE β-receptor agonist isoproterenol (1, 20, or 4 mg/kg), the NE β-receptor antagonist propranolol (10, 20, 40 mg/kg), or saline 30 min prior to training. On day 20, pups received one of the following tests: (1) behavioral conditioned responding, (2) injection with 14C-2-deoxyglucase (2-DG) and exposed to the CS odor, or (3) tested for olfactory bulb mitral/tufted cell single-unit responses to the CS odor. The results indicated that training with either: (1) Odor-Stroke-Saline, (2) Odor-Stroke-lsoproterenol-Propranolol, or (3) Odor only-lsoproterenol (2 mg/kg) was sufficient to produce a learned behavioral odor preference, enhanced uptake of 14C-2-DG in the odor-specific foci within the bulb, and a modified output signal from the bulb as measured by single-cell recordings of mitral/tufted cells. Moreover, propranolol injected prior to Odor-Stroke training blocked the acquisition of both the learned behavior and olfactory bulb responses. PMID:2585063

The role of social relationships in the link between olfactory dysfunction and mortality.

PubMed

Leschak, Carrianne J; Eisenberger, Naomi I

2018-01-01

Recent work suggests that olfactory dysfunction is a strong predictor of five-year mortality in older adults. Based on past work showing: 1) that olfactory dysfunction impairs social functioning and 2) that social ties are linked with mortality, the current work explored whether impairments in social life mediated the relationship between olfactory dysfunction and mortality. Additionally, based on work showing gender differences in the social consequences of olfactory dysfunction, gender was assessed as a potential moderator of this association. Social network size mediated the olfactory-mortality link for females. To probe what feature of social networks was driving this effect, we investigated two subcomponents of social life: emotional closeness (e.g., perceived social support, loneliness) and physical closeness (e.g., physical contact, in-person socializing with others). Physical closeness significantly mediated the olfactory-mortality link for females, even after controlling for social network size. Emotional closeness did not mediate this link. Possible mechanisms underlying this relationship are discussed.

Aversive olfactory associative memory loses odor specificity over time

PubMed Central

König, Christian; Antwi-Adjei, Emmanuel; Ganesan, Mathangi; Kilonzo, Kasyoka; Viswanathan, Vignesh; Durairaja, Archana; Voigt, Anne

2017-01-01

ABSTRACT Avoiding associatively learned predictors of danger is crucial for survival. Aversive memories can, however, become counter-adaptive when they are overly generalized to harmless cues and contexts. In a fruit fly odor–electric shock associative memory paradigm, we found that learned avoidance lost its specificity for the trained odor and became general to novel odors within a day of training. We discuss the possible neural circuit mechanisms of this effect and highlight the parallelism to over-generalization of learned fear behavior after an incubation period in rodents and humans, with due relevance for post-traumatic stress disorder. PMID:28468811

[Learning and memory in Drosophila: physiologic and genetic bases].

PubMed

Zhuravlev, A V; Nikitina, E A; Savvateeva-Popova, E V

2015-01-01

Elucidation of molecular mechanisms of cognitive functions is one of the major achievements in neurobiology. At most, this is due to the studies on the simple nervous systems, such as the CNS in Drosophila melanogaster. Many of its functional characteristics are pretty similar to higher vertebrates. Among these are: 1) evolutionary conservation of genes and molecular systems involved in the regulation of learning acquisition and memory formation; 2) presence of highly specialized and differentiated sensory, associative and motor centers; 3) utilization of similar modes of informational coding and analysis; 4) availability of major learning forms including non-associative, as well as associative learning; 5) diversity of different memories, including short-term- and protein synthesis- dependent long-term memory; 6) presence of aminergic reinforcement systems in the brain; 7) feed-back loops of circadian clocks, current organism experience and individual organism characters affecting cognitive process per se. In this review the main attention is paid to the two mostly studied Drosophila learning forms, namely to olfactory Iearning and courtship suppression conditioning (CCS). A separate consideration is given to the impacts of kynurenins and metabolite of actin remodeling signal cascade.

Active Sampling State Dynamically Enhances Olfactory Bulb Odor Representation.

PubMed

Jordan, Rebecca; Fukunaga, Izumi; Kollo, Mihaly; Schaefer, Andreas T

2018-06-27

The olfactory bulb (OB) is the first site of synaptic odor information processing, yet a wealth of contextual and learned information has been described in its activity. To investigate the mechanistic basis of contextual modulation, we use whole-cell recordings to measure odor responses across rapid learning episodes in identified mitral/tufted cells (MTCs). Across these learning episodes, diverse response changes occur already during the first sniff cycle. Motivated mice develop active sniffing strategies across learning that robustly correspond to the odor response changes, resulting in enhanced odor representation. Evoking fast sniffing in different behavioral states demonstrates that response changes during active sampling exceed those predicted from feedforward input alone. Finally, response changes are highly correlated in tufted cells, but not mitral cells, indicating there are cell-type-specific effects on odor representation during active sampling. Altogether, we show that active sampling is strongly associated with enhanced OB responsiveness on rapid timescales. Copyright © 2018 The Francis Crick Institute. Published by Elsevier Inc. All rights reserved.

Drosophila Learn Opposing Components of a Compound Food Stimulus

PubMed Central

Das, Gaurav; Klappenbach, Martín; Vrontou, Eleftheria; Perisse, Emmanuel; Clark, Christopher M.; Burke, Christopher J.; Waddell, Scott

2014-01-01

Summary Dopaminergic neurons provide value signals in mammals and insects [1–3]. During Drosophila olfactory learning, distinct subsets of dopaminergic neurons appear to assign either positive or negative value to odor representations in mushroom body neurons [4–9]. However, it is not known how flies evaluate substances that have mixed valence. Here we show that flies form short-lived aversive olfactory memories when trained with odors and sugars that are contaminated with the common insect repellent DEET. This DEET-aversive learning required the MB-MP1 dopaminergic neurons that are also required for shock learning [7]. Moreover, differential conditioning with DEET versus shock suggests that formation of these distinct aversive olfactory memories relies on a common negatively reinforcing dopaminergic mechanism. Surprisingly, as time passed after training, the behavior of DEET-sugar-trained flies reversed from conditioned odor avoidance into odor approach. In addition, flies that were compromised for reward learning exhibited a more robust and longer-lived aversive-DEET memory. These data demonstrate that flies independently process the DEET and sugar components to form parallel aversive and appetitive olfactory memories, with distinct kinetics, that compete to guide learned behavior. PMID:25042590

Olfactory memory formation and the influence of reward pathway during appetitive learning by honey bees.

PubMed

Wright, Geraldine A; Mustard, Julie A; Kottcamp, Sonya M; Smith, Brian H

2007-11-01

Animals possess the ability to assess food quality via taste and via changes in state that occur after ingestion. Here, we investigate the extent to which a honey bee's ability to assess food quality affected the formation of association with an odor stimulus and the retention of olfactory memories associated with reward. We used three different conditioning protocols in which the unconditioned stimulus (food) was delivered as sucrose stimulation to the proboscis (mouthparts), the antennae or to both proboscis and antennae. All means of delivery of the unconditioned stimulus produced robust associative conditioning with an odor. However, the memory of a conditioned odor decayed at a significantly greater rate for subjects experiencing antennal-only stimulation after either multiple- or single-trial conditioning. Finally, to test whether the act of feeding on a reward containing sucrose during conditioning affected olfactory memory formation, we conditioned honey bees to associate an odor with antennal stimulation with sucrose followed by feeding on a water droplet. We observed that a honey bee's ability to recall the conditioned odor was not significantly different from that of subjects conditioned with an antennal-only sucrose stimulus. Our results show that stimulation of the sensory receptors on the proboscis and/or ingestion of the sucrose reward during appetitive olfactory conditioning are necessary for long-term memory formation.

Olfactory system gamma oscillations: the physiological dissection of a cognitive neural system

PubMed Central

Rojas-Líbano, Daniel

2008-01-01

Oscillatory phenomena have been a focus of dynamical systems research since the time of the classical studies on the pendulum by Galileo. Fast cortical oscillations also have a long and storied history in neurophysiology, and olfactory oscillations have led the way with a depth of explanation not present in the literature of most other cortical systems. From the earliest studies of odor-evoked oscillations by Adrian, many reports have focused on mechanisms and functional associations of these oscillations, in particular for the so-called gamma oscillations. As a result, much information is now available regarding the biophysical mechanisms that underlie the oscillations in the mammalian olfactory system. Recent studies have expanded on these and addressed functionality directly in mammals and in the analogous insect system. Sub-bands within the rodent gamma oscillatory band associated with specific behavioral and cognitive states have also been identified. All this makes oscillatory neuronal networks a unique interdisciplinary platform from which to study neurocognitive and dynamical phenomena in intact, freely behaving animals. We present here a summary of what has been learned about the functional role and mechanisms of gamma oscillations in the olfactory system as a guide for similar studies in other cortical systems. PMID:19003484

‘Peer pressure’ in larval Drosophila?

PubMed Central

Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

2014-01-01

ABSTRACT Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on ‘peer pressure’, that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. PMID:24907371

'Peer pressure' in larval Drosophila?

PubMed

Niewalda, Thomas; Jeske, Ines; Michels, Birgit; Gerber, Bertram

2014-06-06

Understanding social behaviour requires a study case that is simple enough to be tractable, yet complex enough to remain interesting. Do larval Drosophila meet these requirements? In a broad sense, this question can refer to effects of the mere presence of other larvae on the behaviour of a target individual. Here we focused in a more strict sense on 'peer pressure', that is on the question of whether the behaviour of a target individual larva is affected by what a surrounding group of larvae is doing. We found that innate olfactory preference of a target individual was neither affected (i) by the level of innate olfactory preference in the surrounding group nor (ii) by the expression of learned olfactory preference in the group. Likewise, learned olfactory preference of a target individual was neither affected (iii) by the level of innate olfactory preference of the surrounding group nor (iv) by the learned olfactory preference the group was expressing. We conclude that larval Drosophila thus do not take note of specifically what surrounding larvae are doing. This implies that in a strict sense, and to the extent tested, there is no social interaction between larvae. These results validate widely used en mass approaches to the behaviour of larval Drosophila. © 2014. Published by The Company of Biologists Ltd.

Resistance to Interference of Olfactory Perceptual Learning

ERIC Educational Resources Information Center

Stevenson, Richard J.; Case, Trevor I.; Tomiczek, Caroline

2007-01-01

Olfactory memory is especially persistent. The current study explored whether this applies to a form of perceptual learning, in which experience of an odor mixture results in greater judged similarity between its elements. Experiment 1A contrasted 2 forms of interference procedure, "compound" (mixture AW, followed by presentation of new mixtures…

Long-term episodic memory decline is associated with olfactory deficits only in carriers of ApoE-є4.

PubMed

Olofsson, Jonas K; Josefsson, Maria; Ekström, Ingrid; Wilson, Donald; Nyberg, Lars; Nordin, Steven; Nordin Adolfsson, Annelie; Adolfsson, Rolf; Nilsson, Lars-Göran; Larsson, Maria

2016-05-01

The ɛ4 allele of the Apolipoprotein E gene is a genetic risk factor for late-onset dementia of the Alzheimers' type (DAT), which is characterized by loss of both episodic memory and olfactory functions. Little is known about the possible role of ɛ4 in the association between ongoing episodic memory decline and olfactory deficits in the general population, but such information is relevant in determining the relevance of olfaction as a marker of DAT risk. The present study was based on a large, population-based sample (n=1087, aged 45-90 years, of which 324 were ɛ4-carriers). Episodic memory change rates were established using data collected every 5 years for a 10-20 year interval leading up to an olfactory assessment using the Scandinavian Odor Identification Test at the last wave of data collection. Participants were classified according to whether or not their episodic memory ability declined more rapidly than the age-typical norm (by >1SD). Our main result is that only in ɛ4-carriers was episodic memory decline associated with odor identification impairment. In individuals without ɛ4, odor identification was unrelated to episodic memory decline status. Follow-up analyses indicated that this moderation by ɛ4 was due to the olfactory nature of the identification test, and that the effect was not caused by 63 individuals with dementia. Our results suggest that the ɛ4 determines the functional association between ongoing episodic memory decline and olfaction. These findings are consistent with the notion that ɛ4-carriers with DAT, compared to non-carriers, display a cortical atrophy pattern that is more focused on mediotemporal lobe regions supporting olfactory and episodic memory functions. Olfactory and memory assessments might provide complementary information on mediotemporal atrophy prior to clinical dementia onset, but the ɛ4 should be considered when using olfactory assessment as an early-stage indicator. Copyright © 2016. Published by Elsevier Ltd.

Distinct molecular underpinnings of Drosophila olfactory trace conditioning

PubMed Central

Shuai, Yichun; Hu, Ying; Qin, Hongtao; Campbell, Robert A. A.; Zhong, Yi

2011-01-01

Trace conditioning is valued as a simple experimental model to assess how the brain associates events that are discrete in time. Here, we adapted an olfactory trace conditioning procedure in Drosophila melanogaster by training fruit flies to avoid an odor that is followed by foot shock many seconds later. The molecular underpinnings of the learning are distinct from the well-characterized simultaneous conditioning, where odor and punishment temporally overlap. First, Rutabaga adenylyl cyclase (Rut-AC), a putative molecular coincidence detector vital for simultaneous conditioning, is dispensable in trace conditioning. Second, dominant-negative Rac expression, thought to sustain early labile memory, significantly enhances learning of trace conditioning, but leaves simultaneous conditioning unaffected. We further show that targeting Rac inhibition to the mushroom body (MB) but not the antennal lobe (AL) suffices to achieve the enhancement effect. Moreover, the absence of trace conditioning learning in D1 dopamine receptor mutants is rescued by restoration of expression specifically in the adult MB. These results suggest the MB as a crucial neuroanatomical locus for trace conditioning, which may harbor a Rac activity-sensitive olfactory “sensory buffer” that later converges with the punishment signal carried by dopamine signaling. The distinct molecular signature of trace conditioning revealed here shall contribute to the understanding of how the brain overcomes a temporal gap in potentially related events. PMID:22123966

Peripheral and Central Olfactory Tuning in a Moth

PubMed Central

Ong, Rose C.

2012-01-01

Animals can be innately attracted to certain odorants. Because these attractants are particularly salient, they might be expected to induce relatively strong responses throughout the olfactory pathway, helping animals detect the most relevant odors but limiting flexibility to respond to other odors. Alternatively, specific neural wiring might link innately preferred odors to appropriate behaviors without a need for intensity biases. How nonpheromonal attractants are processed by the general olfactory system remains largely unknown. In the moth Manduca sexta, we studied this with a set of innately preferred host plant odors and other, neutral odors. Electroantennogram recordings showed that, as a population, olfactory receptor neurons (ORNs) did not respond with greater intensity to host plant odors, and further local field potential recordings showed that no specific amplification of signals induced by host plant odors occurred between the first olfactory center and the second. Moreover, when odorants were mutually diluted to elicit equally intense output from the ORNs, moths were able to learn to associate all tested odorants equally well with food reward. Together, these results suggest that, although nonpheromonal host plant odors activate broadly distributed responses, they may be linked to attractive behaviors mainly through specific wiring in the brain. PMID:22362866

Kin recognition in zebrafish: a 24-hour window for olfactory imprinting

PubMed Central

Gerlach, Gabriele; Hodgins-Davis, Andrea; Avolio, Carla; Schunter, Celia

2008-01-01

Distinguishing kin from non-kin profoundly impacts the evolution of social behaviour. Individuals able to assess the genetic relatedness of conspecifics can preferentially allocate resources towards related individuals and avoid inbreeding. We have addressed the question of how animals acquire the ability to recognize kin by studying the development of olfactory kin preference in zebrafish (Danio rerio). Previously, we showed that zebrafish use an olfactory template to recognize even unfamiliar kin through phenotype matching. Here, we show for the first time that this phenotype matching is based on a learned olfactory imprinting process in which exposure to kin individuals on day 6 post fertilization (pf) is necessary and sufficient for imprinting. Larvae that were exposed to kin before or after but not on day 6 pf did not recognize kin. Larvae isolated from all contact with conspecifics did not imprint on their own chemical cues; therefore, we see no evidence for kin recognition through self-matching in this species. Surprisingly, exposure to non-kin odour during the sensitive phase of development did not result in imprinting on the odour cues of unrelated individuals, suggesting a genetic predisposition to kin odour. Urine-born peptides expressed by genes of the immune system (MHC) are important messengers carrying information about ‘self’ and ‘other’. We suggest that phenotype matching is acquired through a time-sensitive learning process that, in zebrafish, includes a genetic predisposition potentially involving MHC genes expressed in the olfactory receptor neurons. PMID:18544507

Kin recognition in zebrafish: a 24-hour window for olfactory imprinting.

PubMed

Gerlach, Gabriele; Hodgins-Davis, Andrea; Avolio, Carla; Schunter, Celia

2008-09-22

Distinguishing kin from non-kin profoundly impacts the evolution of social behaviour. Individuals able to assess the genetic relatedness of conspecifics can preferentially allocate resources towards related individuals and avoid inbreeding. We have addressed the question of how animals acquire the ability to recognize kin by studying the development of olfactory kin preference in zebrafish (Danio rerio). Previously, we showed that zebrafish use an olfactory template to recognize even unfamiliar kin through phenotype matching. Here, we show for the first time that this phenotype matching is based on a learned olfactory imprinting process in which exposure to kin individuals on day 6 post fertilization (pf) is necessary and sufficient for imprinting. Larvae that were exposed to kin before or after but not on day 6 pf did not recognize kin. Larvae isolated from all contact with conspecifics did not imprint on their own chemical cues; therefore, we see no evidence for kin recognition through self-matching in this species. Surprisingly, exposure to non-kin odour during the sensitive phase of development did not result in imprinting on the odour cues of unrelated individuals, suggesting a genetic predisposition to kin odour. Urine-born peptides expressed by genes of the immune system (MHC) are important messengers carrying information about 'self' and 'other'. We suggest that phenotype matching is acquired through a time-sensitive learning process that, in zebrafish, includes a genetic predisposition potentially involving MHC genes expressed in the olfactory receptor neurons.

A processing architecture for associative short-term memory in electronic noses

NASA Astrophysics Data System (ADS)

Pioggia, G.; Ferro, M.; Di Francesco, F.; DeRossi, D.

2006-11-01

Electronic nose (e-nose) architectures usually consist of several modules that process various tasks such as control, data acquisition, data filtering, feature selection and pattern analysis. Heterogeneous techniques derived from chemometrics, neural networks, and fuzzy rules used to implement such tasks may lead to issues concerning module interconnection and cooperation. Moreover, a new learning phase is mandatory once new measurements have been added to the dataset, thus causing changes in the previously derived model. Consequently, if a loss in the previous learning occurs (catastrophic interference), real-time applications of e-noses are limited. To overcome these problems this paper presents an architecture for dynamic and efficient management of multi-transducer data processing techniques and for saving an associative short-term memory of the previously learned model. The architecture implements an artificial model of a hippocampus-based working memory, enabling the system to be ready for real-time applications. Starting from the base models available in the architecture core, dedicated models for neurons, maps and connections were tailored to an artificial olfactory system devoted to analysing olive oil. In order to verify the ability of the processing architecture in associative and short-term memory, a paired-associate learning test was applied. The avoidance of catastrophic interference was observed.

Cholinergic Modulation during Acquisition of Olfactory Fear Conditioning Alters Learning and Stimulus Generalization in Mice

ERIC Educational Resources Information Center

Pavesi, Eloisa; Gooch, Allison; Lee, Elizabeth; Fletcher, Max L.

2013-01-01

We investigated the role of cholinergic neurotransmission in olfactory fear learning. Mice receiving pairings of odor and foot shock displayed fear to the trained odor the following day. Pretraining injections of the nicotinic antagonist mecamylamine had no effect on subsequent freezing, while the muscarinic antagonist scopolamine significantly…

The role of the Drosophila lateral horn in olfactory information processing and behavioral response.

PubMed

Schultzhaus, Janna N; Saleem, Sehresh; Iftikhar, Hina; Carney, Ginger E

2017-04-01

Animals must rapidly and accurately process environmental information to produce the correct behavioral responses. Reactions to previously encountered as well as to novel but biologically important stimuli are equally important, and one understudied region in the insect brain plays a role in processing both types of stimuli. The lateral horn is a higher order processing center that mainly processes olfactory information and is linked via olfactory projection neurons to another higher order learning center, the mushroom body. This review focuses on the lateral horn of Drosophila where most functional studies have been performed. We discuss connectivity between the primary olfactory center, the antennal lobe, and the lateral horn and mushroom body. We also present evidence for the lateral horn playing roles in innate behavioral responses by encoding biological valence to novel odor cues and in learned responses to previously encountered odors by modulating neural activity within the mushroom body. We describe how these processes contribute to acceptance or avoidance of appropriate or inappropriate mates and food, as well as the identification of predators. The lateral horn is a sexually dimorphic and plastic region of the brain that modulates other regions of the brain to ensure that insects produce rapid and effective behavioral responses to both novel and learned stimuli, yet multiple gaps exist in our knowledge of this important center. We anticipate that future studies on olfactory processing, learning, and innate behavioral responses will include the lateral horn in their examinations, leading to a more comprehensive understanding of olfactory information relay and resulting behaviors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Brain composition and olfactory learning in honey bees

PubMed Central

Gronenberg, Wulfila; Couvillon, Margaret J.

2015-01-01

Correlations between brain or brain component size and behavioral measures are frequently studied by comparing different animal species, which sometimes introduces variables that complicate interpretation in terms of brain function. Here, we have analyzed the brain composition of honey bees (Apis mellifera) that have been individually tested in an olfactory learning paradigm. We found that the total brain size correlated with the bees’ learning performance. Among different brain components, only the mushroom body, a structure known to be involved in learning and memory, showed a positive correlation with learning performance. In contrast, visual neuropils were relatively smaller in bees that performed better in the olfactory learning task, suggesting modality-specific behavioral specialization of individual bees. This idea is also supported by inter-individual differences in brain composition. Some slight yet statistically significant differences in the brain composition of European and Africanized honey bees are reported. Larger bees had larger brains, and by comparing brains of different sizes, we report isometric correlations for all brain components except for a small structure, the central body. PMID:20060918

Developmentally defined forebrain circuits regulate appetitive and aversive olfactory learning.

PubMed

Muthusamy, Nagendran; Zhang, Xuying; Johnson, Caroline A; Yadav, Prem N; Ghashghaei, H Troy

2017-01-01

Postnatal and adult neurogenesis are region- and modality-specific, but the significance of developmentally distinct neuronal populations remains unclear. We demonstrate that chemogenetic inactivation of a subset of forebrain and olfactory neurons generated at birth disrupts responses to an aversive odor. In contrast, novel appetitive odor learning is sensitive to inactivation of adult-born neurons, revealing that developmentally defined sets of neurons may differentially participate in hedonic aspects of sensory learning.

The impact of expertise in olfaction

PubMed Central

Royet, Jean-Pierre; Plailly, Jane; Saive, Anne-Lise; Veyrac, Alexandra; Delon-Martin, Chantal

2013-01-01

Olfactory expertise remains poorly understood, most likely because experts in odor, such as perfumers, sommeliers, and oenologists, are much rarer than experts in other modalities, such as musicians or sportsmen. In this review, we address the specificities of odor expertise in both odor experts and in a priori untrained individuals who have undergone specific olfactory training in the frame of an experiment, such as repeated exposure to odors or associative learning. Until the 21st century, only the behavioral effects of olfactory training of untrained control individuals had been reported, revealing an improvement of olfactory performance in terms of sensitivity, discrimination, memory, and identification. Behavioral studies of odor experts have been scarce, with inconsistent or inconclusive results. Recently, the development of cerebral imaging techniques has enabled the identification of brain areas and neural networks involved in odor processing, revealing functional and structural modifications as a function of experience. The behavioral approach to odor expertise has also evolved. Researchers have particularly focused on odor mental imagery, which is characteristic of odor experts, because this ability is absent in the average person but is part of a perfumer’s professional practice. This review summarizes behavioral, functional, and structural findings on odor expertise. These data are compared with those obtained using animals subjected to prolonged olfactory exposure or to olfactory-enriched environments and are discussed in the context of functional and structural plasticity. PMID:24379793

DNA Methylation Adjusts the Specificity of Memories Depending on the Learning Context and Promotes Relearning in Honeybees

PubMed Central

Biergans, Stephanie D.; Claudianos, Charles; Reinhard, Judith; Galizia, C. G.

2016-01-01

The activity of the epigenetic writers DNA methyltransferases (Dnmts) after olfactory reward conditioning is important for both stimulus-specific long-term memory (LTM) formation and extinction. It, however, remains unknown which components of memory formation Dnmts regulate (e.g., associative vs. non-associative) and in what context (e.g., varying training conditions). Here, we address these aspects in order to clarify the role of Dnmt-mediated DNA methylation in memory formation. We used a pharmacological Dnmt inhibitor and classical appetitive conditioning in the honeybee Apis mellifera, a well characterized model for classical conditioning. We quantified the effect of DNA methylation on naïve odor and sugar responses, and on responses following olfactory reward conditioning. We show that (1) Dnmts do not influence naïve odor or sugar responses, (2) Dnmts do not affect the learning of new stimuli, but (3) Dnmts influence odor-coding, i.e., ‘correct’ (stimulus-specific) LTM formation. Particularly, Dnmts reduce memory specificity when experience is low (one-trial training), and increase memory specificity when experience is high (multiple-trial training), generating an ecologically more useful response to learning. (4) In reversal learning conditions, Dnmts are involved in regulating both excitatory (re-acquisition) and inhibitory (forgetting) processes. PMID:27672359

DNA Methylation Adjusts the Specificity of Memories Depending on the Learning Context and Promotes Relearning in Honeybees.

PubMed

Biergans, Stephanie D; Claudianos, Charles; Reinhard, Judith; Galizia, C G

2016-01-01

The activity of the epigenetic writers DNA methyltransferases (Dnmts) after olfactory reward conditioning is important for both stimulus-specific long-term memory (LTM) formation and extinction. It, however, remains unknown which components of memory formation Dnmts regulate (e.g., associative vs. non-associative) and in what context (e.g., varying training conditions). Here, we address these aspects in order to clarify the role of Dnmt-mediated DNA methylation in memory formation. We used a pharmacological Dnmt inhibitor and classical appetitive conditioning in the honeybee Apis mellifera, a well characterized model for classical conditioning. We quantified the effect of DNA methylation on naïve odor and sugar responses, and on responses following olfactory reward conditioning. We show that (1) Dnmts do not influence naïve odor or sugar responses, (2) Dnmts do not affect the learning of new stimuli, but (3) Dnmts influence odor-coding, i.e., 'correct' (stimulus-specific) LTM formation. Particularly, Dnmts reduce memory specificity when experience is low (one-trial training), and increase memory specificity when experience is high (multiple-trial training), generating an ecologically more useful response to learning. (4) In reversal learning conditions, Dnmts are involved in regulating both excitatory (re-acquisition) and inhibitory (forgetting) processes.

Brain activation associated to olfactory conditioned same-sex partner preference in male rats.

PubMed

Coria-Avila, Genaro A; Cibrian-Llanderal, Tamara; Díaz-Estrada, Victor X; García, Luis I; Toledo-Cárdenas, Rebeca; Pfaus, James G; Manzo, Jorge

2018-03-01

Sexual preferences can be strongly modified by Pavlovian learning. For instance, olfactory conditioned same-sex partner preference can occur when a sexually naïve male cohabits with an scented male during repeated periods under the effects of enhanced D2-type activity. Preference is observed days later via social and sexual behaviors. Herein we explored brain activity related to learned same-sex preference (Fos-Immunoreactivity, IR) following exposure to a conditioned odor paired with same-sex preference. During conditioning trials males received either saline or the D2-type receptor agonist quinpirole (QNP) and cohabitated during 24 h with a stimulus male that bore almond scent on the back as conditioned stimulus. This was repeated every 4 days, for a total of three trials. In a drug-free final test we assessed socio/sexual partner preference between the scented male and a receptive female. The results indicated that QNP-conditioned males developed a same-sex preference observed via contact, time spent, olfactory investigations, and non-contact erections. By contrast, saline-conditioned and intact (non-exposed to conditioning) males expressed an unconditioned preference for the female. Four days later the males were exposed to almond scent and their brains were processed for Fos-IR. Results indicated that the QNP-conditioned group expressed more Fos-IR in the nucleus accumbens (AcbSh), medial preoptic area (MPA), piriform cortex (Pir) and ventromedial nucleus of the hypothalamus (VMH) as compared to saline-conditioned. Intact males expressed the lowest Fos-IR in AcbSh and VMH, but the highest in MPA and Pir. We discuss the role of these areas in the learning process of same-sex partner preferences and olfactory discrimination. Copyright © 2018 Elsevier Inc. All rights reserved.

ϒ Spike-Field Coherence in a Population of Olfactory Bulb Neurons Differentiates between Odors Irrespective of Associated Outcome

PubMed Central

Li, Anan; Gire, David H.

2015-01-01

Studies in different sensory systems indicate that short spike patterns within a spike train that carry items of sensory information can be extracted from the overall train by using field potential oscillations as a reference (Kayser et al., 2012; Panzeri et al., 2014). Here we test the hypothesis that the local field potential (LFP) provides the temporal reference frame needed to differentiate between odors regardless of associated outcome. Experiments were performed in the olfactory system of the mouse (Mus musculus) where the mitral/tufted (M/T) cell spike rate develops differential responses to rewarded and unrewarded odors as the animal learns to associate one of the odors with a reward in a go–no go behavioral task. We found that coherence of spiking in M/T cells with the ϒ LFP (65 to 95 Hz) differentiates between odors regardless of the associated behavioral outcome of odor presentation. PMID:25855190

IGF1-Dependent Synaptic Plasticity of Mitral Cells in Olfactory Memory during Social Learning.

PubMed

Liu, Zhihui; Chen, Zijun; Shang, Congping; Yan, Fei; Shi, Yingchao; Zhang, Jiajing; Qu, Baole; Han, Hailin; Wang, Yanying; Li, Dapeng; Südhof, Thomas C; Cao, Peng

2017-07-05

During social transmission of food preference (STFP), mice form long-term memory of food odors presented by a social partner. How does the brain associate a social context with odor signals to promote memory encoding? Here we show that odor exposure during STFP, but not unconditioned odor exposure, induces glomerulus-specific long-term potentiation (LTP) of synaptic strength selectively at the GABAergic component of dendrodendritic synapses of granule and mitral cells in the olfactory bulb. Conditional deletion of synaptotagmin-10, the Ca 2+ sensor for IGF1 secretion from mitral cells, or deletion of IGF1 receptor in the olfactory bulb prevented the socially relevant GABAergic LTP and impaired memory formation after STFP. Conversely, the addition of IGF1 to acute olfactory bulb slices elicited the GABAergic LTP in mitral cells by enhancing postsynaptic GABA receptor responses. Thus, our data reveal a synaptic substrate for a socially conditioned long-term memory that operates at the level of the initial processing of sensory information. Copyright © 2017 Elsevier Inc. All rights reserved.

Altered Odor-Induced Brain Activity as an Early Manifestation of Cognitive Decline in Patients With Type 2 Diabetes.

PubMed

Zhang, Zhou; Zhang, Bing; Wang, Xin; Zhang, Xin; Yang, Qing X; Qing, Zhao; Lu, Jiaming; Bi, Yan; Zhu, Dalong

2018-05-01

Type 2 diabetes is reported to be associated with olfactory dysfunction and cognitive decline. However, whether and how olfactory neural circuit abnormalities involve cognitive impairment in diabetes remains uncovered. This study thus aimed to investigate olfactory network alterations and the associations of odor-induced brain activity with cognitive and metabolic parameters in type 2 diabetes. Participants with normal cognition, including 51 patients with type 2 diabetes and 41 control subjects without diabetes, underwent detailed cognitive assessment, olfactory behavior tests, and odor-induced functional MRI measurements. Olfactory brain regions showing significantly different activation between the two groups were selected for functional connectivity analysis. Compared with the control subjects, patients with diabetes demonstrated significantly lower olfactory threshold score, decreased brain activation, and disrupted functional connectivity in the olfactory network. Positive associations of the disrupted functional connectivity with decreased neuropsychology test scores and reduced pancreatic function were observed in patients with diabetes. Notably, the association between pancreatic function and executive function was mediated by olfactory behavior and olfactory functional connectivity. Our results suggested the alteration of olfactory network is present before clinically measurable cognitive decrements in type 2 diabetes, bridging the gap between the central olfactory system and cognitive decline in diabetes. © 2018 by the American Diabetes Association.

A Computational Framework for Understanding Decision Making through Integration of Basic Learning Rules

PubMed Central

Bazhenov, Maxim; Huerta, Ramon; Smith, Brian H.

2013-01-01

Nonassociative and associative learning rules simultaneously modify neural circuits. However, it remains unclear how these forms of plasticity interact to produce conditioned responses. Here we integrate nonassociative and associative conditioning within a uniform model of olfactory learning in the honeybee. Honeybees show a fairly abrupt increase in response after a number of conditioning trials. The occurrence of this abrupt change takes many more trials after exposure to nonassociative trials than just using associative conditioning. We found that the interaction of unsupervised and supervised learning rules is critical for explaining latent inhibition phenomenon. Associative conditioning combined with the mutual inhibition between the output neurons produces an abrupt increase in performance despite smooth changes of the synaptic weights. The results show that an integrated set of learning rules implemented using fan-out connectivities together with neural inhibition can explain the broad range of experimental data on learning behaviors. PMID:23536082

A potential link among biogenic amines-based pesticides, learning and memory, and colony collapse disorder: a unique hypothesis.

PubMed

Farooqui, Tahira

2013-01-01

Pesticides are substances that have been widely used throughout the world to kill, repel, or control organisms such as certain forms of plants or animals considered as pests. Depending on their type, dose, and persistence in the environment, they can have impact even on non-target species such as beneficial insects (honeybees) in different ways, including reduction in their survival rate and interference with their reproduction process. Honeybee Apis mellifera is a major pollinator and has substantial economical and ecological values. Colony collapse disorder (CCD) is a mysterious phenomenon in which adult honeybee workers suddenly abandon from their hives, leaving behind food, brood, and queen. It is lately drawing a lot of attention due to pollination crisis as well as global agriculture and medical demands. If the problem of CCD is not resolved soon enough, this could have a major impact on food industry affecting world's economy a big time. Causes of CCD are not known. In this overview, I discuss CCD, biogenic amines-based-pesticides (neonicotinoids and formamidines), and their disruptive effects on biogenic amine signaling causing olfactory dysfunction in honeybees. According to my hypothesis, chronic exposure of biogenic amines-based-pesticides to honeybee foragers in hives and agricultural fields can disrupt neural cholinergic and octopaminergic signaling. Abnormality in biogenic amines-mediated neuronal signaling impairs their olfactory learning and memory, therefore foragers do not return to their hive - a possible cause of CCD. This overview is an attempt to discuss a hypothetical link among biogenic amines-based pesticides, olfactory learning and memory, and CCD. Copyright © 2012 Elsevier Ltd. All rights reserved.

The value of identity: olfactory notes on orbitofrontal cortex function.

PubMed

Gottfried, Jay A; Zelano, Christina

2011-12-01

Neuroscientific research has emphatically promoted the idea that the key function of the orbitofrontal cortex (OFC) is to encode value. Associative learning studies indicate that OFC representations of stimulus cues reflect the predictive value of expected outcomes. Neuroeconomic studies suggest that the OFC distills abstract representations of value from discrete commodities to optimize choice. Although value-based models provide good explanatory power for many different findings, these models are typically disconnected from the very stimuli and commodities giving rise to those value representations. Little provision is made, either theoretically or empirically, for the necessary cooperative role of object identity, without which value becomes orphaned from its source. As a step toward remediating the value of identity, this review provides a focused olfactory survey of OFC research, including new work from our lab, to highlight the elemental involvement of this region in stimulus-specific predictive coding of both perceptual outcomes and expected values. © 2011 New York Academy of Sciences.

Role of olfactory bulb serotonin in olfactory learning in the greater short-nosed fruit bat, Cynopterus sphinx (Chiroptera: Pteropodidae).

PubMed

Ganesh, Ambigapathy; Bogdanowicz, Wieslaw; Haupt, Moritz; Marimuthu, Ganapathy; Rajan, Koilmani Emmanuvel

2010-09-17

The role of olfactory bulb (OB) serotonin [5-hydroxytryptamine (5-HT)] in olfactory learning and memory was tested in the greater short-nosed fruit bat, Cynopterus sphinx (family Pteropodidae). Graded concentrations (25, 40, and 60microg) of 5,7-dihydroxytryptamine (5,7-DHT) or saline were injected into the OB of bats one day before training to the novel odor. In a behavioral test, 5,7-DHT (60microg) injected bats made significantly fewer feeding attempts and bouts when compared to saline-injected bats during learning and in the memory test. Subsequent biochemical analysis showed that 5-HT level was effectively depleted in the OB of 5,7-DHT injected bats. To test odor-induced 5-HT mediated changes in 5-HT receptors and second messenger cascade in the OB, we examined the expression of 5-HT receptors and mitogen-activated protein kinase (MAPK)/Erk cascade after training to the novel odor. We found that odor stimulation up-regulated the expression of 5-HT(1A) receptor, Erk1 and Creb1 mRNA, and phosphorylation of ERK1 and CREB1. Odor stimulation failed to induce expression in 5-HT-depleted bats, which is similar to control bats and significantly low compared to saline-treated bats. Together these data revealed that the level of 5-HT in the OB may regulate olfactory learning and memory in C. sphinx through Erk and CREB.

Presence of neuropathic pain may explain poor performances on olfactory testing in diabetes mellitus patients.

PubMed

Brady, Shauna; Lalli, Paul; Midha, Nisha; Chan, Ayechen; Garven, Alexandra; Chan, Cynthia; Toth, Cory

2013-07-01

Olfactory dysfunction in neurodegenerative conditions such as Parkinson's syndrome and Alzheimer's disease can hallmark disease onset. We hypothesized that patients with diabetes mellitus, a condition featuring peripheral and central neurodegeneration, would have decreased olfaction abilities. We examined participants with diabetic peripheral neuropathy, participants with diabetes without diabetic peripheral neuropathy, and control participants in blinded fashion using standardized Sniffin' Sticks. Diabetic peripheral neuropathy severity was quantified using the Utah Early Neuropathy Scale. Further subcategorization of diabetic peripheral neuropathy based on presence of neuropathic pain was performed with Douleur Neuropathique 4 Questionnaires. Participants with diabetes had decreased olfactory sensitivity, impaired olfactory discrimination abilities, and reduced odor identification skills when compared with controls. However, loss of olfaction ability was, at least partially, attributed to presence of neuropathic pain on subcategory assessment, although pain severity was not associated with dysfunction. Those participants with diabetes without diabetic peripheral neuropathy and those with diabetic peripheral neuropathy without neuropathic pain had similar olfactory function as controls in general. The presence of neuropathic pain, associated with limited attention and concentration, may explain at least a portion of the olfactory dysfunction witnessed in the diabetic patient population.

Causality Assessment of Olfactory and Gustatory Dysfunction Associated with Intranasal Fluticasone Propionate: Application of the Bradford Hill Criteria.

PubMed

Muganurmath, Chandrashekhar S; Curry, Amy L; Schindzielorz, Andrew H

2018-02-01

Causality assessment is crucial to post-marketing pharmacovigilance and helps optimize safe and appropriate use of medicines by patients in the real world. Self-reported olfactory and gustatory dysfunction are common in the general population as well as in patients with allergic rhinitis and nasal polyposis. Intranasal corticosteroids, including intranasal fluticasone propionate (INFP), are amongst the most effective drugs indicated in the treatment of allergic rhinitis and nasal polyposis. While intranasal corticosteroids are associated with olfactory and gustatory dysfunction and are currently labeled for these adverse events, causality assessment has not been performed to date. Although there is no single widely accepted method to assess causality in pharmacovigilance, the Bradford Hill criteria offer a robust and comprehensive approach because nine distinct aspects of an observed potential drug-event association are assessed. In this literature-based narrative review, Hill's criteria were applied to determine causal inference between INFP and olfactory and gustatory dysfunction.

Blocking and the detection of odor components in blends.

PubMed

Hosler, J S; Smith, B H

2000-09-01

Recent studies of olfactory blocking have revealed that binary odorant mixtures are not always processed as though they give rise to mixture-unique configural properties. When animals are conditioned to one odorant (A) and then conditioned to a mixture of that odorant with a second (X), the ability to learn or express the association of X with reinforcement appears to be reduced relative to animals that were not preconditioned to A. A recent model of odor-based response patterns in the insect antennal lobe predicts that the strength of the blocking effect will be related to the perceptual similarity between the two odorants, i.e. greater similarity should increase the blocking effect. Here, we test that model in the honeybee Apis mellifera by first establishing a generalization matrix for three odorants and then testing for blocking between all possible combinations of them. We confirm earlier findings demonstrating the occurrence of the blocking effect in olfactory learning of compound stimuli. We show that the occurrence and the strength of the blocking effect depend on the odorants used in the experiment. In addition, we find very good agreement between our results and the model, and less agreement between our results and an alternative model recently proposed to explain the effect.

Olfactory coding: giant inhibitory neuron governs sparse odor codes.

PubMed

Gupta, Nitin; Stopfer, Mark

2011-07-12

Electrophysiological investigations in locusts have revealed that the sparseness of odor representations, in the brain region expected to mediate olfactory learning, is shaped by a unique inhibitory neuron. Copyright © 2011 Elsevier Ltd. All rights reserved.

Egr-1 antisense oligodeoxynucleotide administration into the olfactory bulb impairs olfactory learning in the greater short-nosed fruit bat Cynopterus sphinx.

PubMed

Ganesh, Ambigapathy; Bogdanowicz, Wieslaw; Balamurugan, Krishnaswamy; Ragu Varman, Durairaj; Rajan, Koilmani Emmanuvel

2012-08-30

Postsynaptic densities (PSDs) contain proteins that regulate synaptic transmission. We examined two important examples of these, calcium/calmodulin-dependent protein kinase II (CaMKII) and PSD-95, in regard to the functional role of early growth response gene-1 (egr-1) in regulation of olfactory learning in the greater short-nosed fruit bat Cynopterus sphinx (family Pteropodidae). To test whether activation of egr-1 in the olfactory bulb (OB) is required for olfactory memory of these bats, bilaterally canulated individuals were infused with antisense (AS) or non-sense (NS)-oligodeoxynucleotides (ODN) of egr-1, or with phosphate buffer saline (PBS), 2h before the olfactory training. Our results showed that behavioral training significantly up-regulates immediate early gene (IEG) EGR-1 and key synaptic proteins Synaptotagmin-1(SYT-1), CaMKII and PSD-95, and phosphorylation of CaMKII in the OB at the protein level per se. Subsequently, we observed that egr-1 antisense-ODN infusion in the OB impaired olfactory memory and down regulates the expression of CaMKII and PSD-95, and the phosphorylation of CaMKII but not SYT-1. In contrast, NS-ODN or PBS had no effect on the expression of the PSDs CaMKII or PSD-95, or on the phosphorylation of CaMKII. When the egr-1 NS-ODN was infused in the OB after training for the novel odor there was no effect on olfactory memory. These findings suggest that egr-1 control the activation of CaMKII and PSD-95 during the process of olfactory memory formation. Copyright © 2012 Elsevier B.V. All rights reserved.

AKAPS Act in a Two-Step Mechanism of Memory Acquisition

PubMed Central

Scheunemann, Lisa; Skroblin, Philipp; Hundsrucker, Christian; Klussmann, Enno; Efetova, Marina

2013-01-01

Defining the molecular and neuronal basis of associative memories is based upon behavioral preparations that yield high performance due to selection of salient stimuli, strong reinforcement, and repeated conditioning trials. One of those preparations is the Drosophila aversive olfactory conditioning procedure where animals initiate multiple memory components after experience of a single cycle training procedure. Here, we explored the analysis of acquisition dynamics as a means to define memory components and revealed strong correlations between particular chronologies of shock impact and number experienced during the associative training situation and subsequent performance of conditioned avoidance. Analyzing acquisition dynamics in Drosophila memory mutants revealed that rutabaga (rut)-dependent cAMP signals couple in a divergent fashion for support of different memory components. In case of anesthesia-sensitive memory (ASM) we identified a characteristic two-step mechanism that links rut-AC1 to A-kinase anchoring proteins (AKAP)-sequestered protein kinase A at the level of Kenyon cells, a recognized center of olfactory learning within the fly brain. We propose that integration of rut-derived cAMP signals at level of AKAPs might serve as counting register that accounts for the two-step mechanism of ASM acquisition. PMID:24174675

Affect in Human-Robot Interaction

DTIC Science & Technology

2014-01-01

is capable of learning and producing a large number of facial expressions based on Ekman’s Facial Action Coding System, FACS (Ekman and Friesen 1978... tactile (pushed, stroked, etc.), auditory (loud sound), temperature and olfactory (alcohol, smoke, etc.). The personality of the robot consists of...robot’s behavior through decision-making, learning , or action selection, a number of researchers used the fuzzy logic approach to emotion generation

A Closer Look at Acid-Base Olfactory Titrations

ERIC Educational Resources Information Center

Neppel, Kerry; Oliver-Hoyo, Maria T.; Queen, Connie; Reed, Nicole

2005-01-01

Olfactory titrations using raw onions and eugenol as acid-base indicators are reported. An in-depth investigation on olfactory titrations is presented to include requirements for potential olfactory indicators and protocols for using garlic, onions, and vanillin as acid-base olfactory indicators are tested.

Early Stage olfactory neuroblastoma and the impact of resecting dura and olfactory bulb.

PubMed

Mays, Ashley C; Bell, Diana; Ferrarotto, Renata; Phan, Jack; Roberts, Dianna; Fuller, Clifton D; Frank, Steven J; Raza, Shaan M; Kupferman, Michael E; DeMonte, Franco; Hanna, Ehab Y; Su, Shirley Y

2018-06-01

Compare outcomes of patients with olfactory neuroblastoma (ONB) without skull base involvement treated with and without resection of the dura and olfactory bulb. Retrospective review of ONB patients treated from 1992 to 2013 at the MD Anderson Cancer Center (The University of Texas, Houston, Texas, U.S.A.). Primary outcomes were overall and disease-free survival. Thirty-five patients were identified. Most patients had Kadish A/B. tumors (97%), Hyams grade 2 (70%), with unilateral involvement (91%), and arising from the nasal cavity (68%). Tumor involved the mucosa abutting the skull base in 42% of patients. Twenty-five patients (71%) received surgery and radiation, whereas the remainder had surgery alone. Five patients (14%) had bony skull base resection, and eight patients (23%) had resection of bony skull base, dura, and olfactory bulb. Surgical margins were grossly positive in one patient (3%) and microscopically positive in four patients (12%). The 5- and 10-year overall survival were 93% and 81%, respectively. The 5- and 10-year disease-free survival (DFS) were 89% and 78%, respectively. Bony cribriform plate resection was associated with better DFS (P = 0.05), but dura and olfactory bulb resection was not (P = 0.11). There was a trend toward improved DFS in patients with negative resection margins (P = 0.19). Surgical modality (open vs. endoscopic) and postoperative radiotherapy did not impact DFS. Most Kadish A/B ONB tumors have low Hyams grade, unilateral involvement, and favorable survival outcomes. Resection of the dura and olfactory bulb is not oncologically advantageous in patients without skull base involvement who are surgically treated with negative resection margins and cribriform resection. 4. Laryngoscope, 128:1274-1280, 2018. © 2017 The American Laryngological, Rhinological and Otological Society, Inc.

Olfactory Impairment in Chronic Rhinosinusitis Using Threshold, Discrimination, and Identification Scores

PubMed Central

Kohli, Preeti; Storck, Kristina A.; Schlosser, Rodney J.

2016-01-01

Differences in testing modalities and cut-points used to define olfactory dysfunction contribute to the wide variability in estimating the prevalence of olfactory dysfunction in chronic rhinosinusitis (CRS). The aim of this study is to report the prevalence of olfactory impairment using each component of the Sniffin’ Sticks test (threshold, discrimination, identification, and total score) with age-adjusted and ideal cut-points from normative populations. Patients meeting diagnostic criteria for CRS were enrolled from rhinology clinics at a tertiary academic center. Olfaction was assessed using the Sniffin’ Sticks test. The study population consisted of 110 patients. The prevalence of normosmia, hyposmia, and anosmia using total Sniffin’ Sticks score was 41.8%, 20.0%, and 38.2% using age-appropriate cut-points and 20.9%, 40.9%, and 38.2% using ideal cut-points. Olfactory impairment estimates for each dimension mirrored these findings, with threshold yielding the highest values. Threshold, discrimination, and identification were also found to be significantly correlated to each other (P < 0.001). In addition, computed tomography scores, asthma, allergy, and diabetes were found to be associated with olfactory dysfunction. In conclusion, the prevalence of olfactory dysfunction is dependent upon olfactory dimension and if age-adjusted cut-points are used. The method of olfactory testing should be chosen based upon specific clinical and research goals. PMID:27469973

c-Fos expression predicts long-term social memory retrieval in mice.

PubMed

Lüscher Dias, Thomaz; Fernandes Golino, Hudson; Moura de Oliveira, Vinícius Elias; Dutra Moraes, Márcio Flávio; Schenatto Pereira, Grace

2016-10-15

The way the rodent brain generally processes socially relevant information is rather well understood. How social information is stored into long-term social memory, however, is still under debate. Here, brain c-Fos expression was measured after adult mice were exposed to familiar or novel juveniles and expression was compared in several memory and socially relevant brain areas. Machine Learning algorithm Random Forest was then used to predict the social interaction category of adult mice based on c-Fos expression in these areas. Interaction with a familiar co-specific altered brain activation in the olfactory bulb, amygdala, hippocampus, lateral septum and medial prefrontal cortex. Remarkably, Random Forest was able to predict interaction with a familiar juvenile with 100% accuracy. Activity in the olfactory bulb, amygdala, hippocampus and the medial prefrontal cortex were crucial to this prediction. From our results, we suggest long-term social memory depends on initial social olfactory processing in the medial amygdala and its output connections synergistically with non-social contextual integration by the hippocampus and medial prefrontal cortex top-down modulation of primary olfactory structures. Copyright © 2016 Elsevier B.V. All rights reserved.

NMDA Receptors Mediate Olfactory Learning and Memory in Drosophila

PubMed Central

Xia, Shouzhen; Miyashita, Tomoyuki; Fu, Tsai-Feng; Lin, Wei-Yong; Wu, Chia-Lin; Pyzocha, Lori; Lin, Inn-Ray; Saitoe, Minoru; Tully, Tim; Chiang, Ann-Shyn

2011-01-01

Summary Background Molecular and electrophysiological properties of NMDARs suggest that they may be the Hebbian “coincidence detectors” hypothesized to underlie associative learning. Because of the nonspecificity of drugs that modulate NMDAR function or the relatively chronic genetic manipulations of various NMDAR subunits from mammalian studies, conclusive evidence for such an acute role for NMDARs in adult behavioral plasticity, however, is lacking. Moreover, a role for NMDARs in memory consolidation remains controversial. Results The Drosophila genome encodes two NMDAR homologs, dNR1 and dNR2. When coexpressed in Xenopus oocytes or Drosophila S2 cells, dNR1 and dNR2 form functional NMDARs with several of the distinguishing molecular properties observed for vertebrate NMDARs, including voltage/Mg2+-dependent activation by glutamate. Both proteins are weakly expressed throughout the entire brain but show preferential expression in several neurons surrounding the dendritic region of the mushroom bodies. Hypomorphic mutations of the essential dNR1 gene disrupt olfactory learning, and this learning defect is rescued with wild-type transgenes. Importantly, we show that Pavlovian learning is disrupted in adults within 15 hr after transient induction of a dNR1 antisense RNA transgene. Extended training is sufficient to overcome this initial learning defect, but long-term memory (LTM) specifically is abolished under these training conditions. Conclusions Our study uses a combination of molecular-genetic tools to (1) generate genomic mutations of the dNR1 gene, (2) rescue the accompanying learning deficit with a dNR1+ transgene, and (3) rapidly and transiently knockdown dNR1+ expression in adults, thereby demonstrating an evolutionarily conserved role for the acute involvement of NMDARs in associative learning and memory. PMID:15823532

NMDA receptors mediate olfactory learning and memory in Drosophila.

PubMed

Xia, Shouzhen; Miyashita, Tomoyuki; Fu, Tsai-Feng; Lin, Wei-Yong; Wu, Chia-Lin; Pyzocha, Lori; Lin, Inn-Ray; Saitoe, Minoru; Tully, Tim; Chiang, Ann-Shyn

2005-04-12

Molecular and electrophysiological properties of NMDARs suggest that they may be the Hebbian "coincidence detectors" hypothesized to underlie associative learning. Because of the nonspecificity of drugs that modulate NMDAR function or the relatively chronic genetic manipulations of various NMDAR subunits from mammalian studies, conclusive evidence for such an acute role for NMDARs in adult behavioral plasticity, however, is lacking. Moreover, a role for NMDARs in memory consolidation remains controversial. The Drosophila genome encodes two NMDAR homologs, dNR1 and dNR2. When coexpressed in Xenopus oocytes or Drosophila S2 cells, dNR1 and dNR2 form functional NMDARs with several of the distinguishing molecular properties observed for vertebrate NMDARs, including voltage/Mg(2+)-dependent activation by glutamate. Both proteins are weakly expressed throughout the entire brain but show preferential expression in several neurons surrounding the dendritic region of the mushroom bodies. Hypomorphic mutations of the essential dNR1 gene disrupt olfactory learning, and this learning defect is rescued with wild-type transgenes. Importantly, we show that Pavlovian learning is disrupted in adults within 15 hr after transient induction of a dNR1 antisense RNA transgene. Extended training is sufficient to overcome this initial learning defect, but long-term memory (LTM) specifically is abolished under these training conditions. Our study uses a combination of molecular-genetic tools to (1) generate genomic mutations of the dNR1 gene, (2) rescue the accompanying learning deficit with a dNR1+ transgene, and (3) rapidly and transiently knockdown dNR1+ expression in adults, thereby demonstrating an evolutionarily conserved role for the acute involvement of NMDARs in associative learning and memory.

Age-associated loss of selectivity in human olfactory sensory neurons

PubMed Central

Rawson, Nancy E.; Gomez, George; Cowart, Beverly J.; Kriete, Andres; Pribitkin, Edmund; Restrepo, Diego

2011-01-01

We report a cross-sectional study of olfactory impairment with age based on both odorant-stimulated responses of human olfactory sensory neurons (OSNs) and tests of olfactory threshold sensitivity. A total of 621 OSNs from 440 subjects in two age groups of younger ( 45 years) and older (≥60 years) subjects were investigated using fluorescence intensity ratio fura-2 imaging. OSNs were tested for responses to two odorant mixtures, as well as to subsets of and individual odors in those mixtures. Whereas cells from younger donors were highly selective in the odorants to which they responded, cells from older donors were more likely to respond to multiple odor stimuli, despite a loss in these subjects’ absolute olfactory sensitivity, suggesting a loss of specificity. This degradation in peripheral cellular specificity may impact odor discrimination and olfactory adaptation in the elderly. It is also possible that chronic adaptation as a result of reduced specificity contributes to observed declines in absolute sensitivity. PMID:22074806

Context-Dependent Olfactory Learning in an Insect

ERIC Educational Resources Information Center

Matsumoto, Yukihisa; Mizunami, Makoto

2004-01-01

We studied the capability of the cricket "Gryllus bimaculatus" to select one of a pair of odors and to avoid the other in one context and to do the opposite in another context. One group of crickets was trained to associate one of a pair of odors (conditioned stimulus, CS1) with water reward (appetitive unconditioned stimulus, US+) and another…

The vomeronasal cortex - afferent and efferent projections of the posteromedial cortical nucleus of the amygdala in mice.

PubMed

Gutiérrez-Castellanos, Nicolás; Pardo-Bellver, Cecília; Martínez-García, Fernando; Lanuza, Enrique

2014-01-01

Most mammals possess a vomeronasal system that detects predominantly chemical signals of biological relevance. Vomeronasal information is relayed to the accessory olfactory bulb (AOB), whose unique cortical target is the posteromedial cortical nucleus of the amygdala. This cortical structure should therefore be considered the primary vomeronasal cortex. In the present work, we describe the afferent and efferent connections of the posteromedial cortical nucleus of the amygdala in female mice, using anterograde (biotinylated dextranamines) and retrograde (Fluorogold) tracers, and zinc selenite as a tracer specific for zinc-enriched (putative glutamatergic) projections. The results show that the posteromedial cortical nucleus of the amygdala is strongly interconnected not only with the rest of the vomeronasal system (AOB and its target structures in the amygdala), but also with the olfactory system (piriform cortex, olfactory-recipient nuclei of the amygdala and entorhinal cortex). Therefore, the posteromedial cortical nucleus of the amygdala probably integrates olfactory and vomeronasal information. In addition, the posteromedial cortical nucleus of the amygdala shows moderate interconnections with the associative (basomedial) amygdala and with the ventral hippocampus, which may be involved in emotional and spatial learning (respectively) induced by chemical signals. Finally, the posteromedial cortical nucleus of the amygdala gives rise to zinc-enriched projections to the ventrolateral septum and the ventromedial striatum (including the medial islands of Calleja). This pattern of intracortical connections (with the olfactory cortex and hippocampus, mainly) and cortico-striatal excitatory projections (with the olfactory tubercle and septum) is consistent with its proposed nature as the primary vomeronasal cortex. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.

Color-dependent learning in restrained Africanized honey bees.

PubMed

Jernigan, C M; Roubik, D W; Wcislo, W T; Riveros, A J

2014-02-01

Associative color learning has been demonstrated to be very poor using restrained European honey bees unless the antennae are amputated. Consequently, our understanding of proximate mechanisms in visual information processing is handicapped. Here we test learning performance of Africanized honey bees under restrained conditions with visual and olfactory stimulation using the proboscis extension response (PER) protocol. Restrained individuals were trained to learn an association between a color stimulus and a sugar-water reward. We evaluated performance for 'absolute' learning (learned association between a stimulus and a reward) and 'discriminant' learning (discrimination between two stimuli). Restrained Africanized honey bees (AHBs) readily learned the association of color stimulus for both blue and green LED stimuli in absolute and discriminatory learning tasks within seven presentations, but not with violet as the rewarded color. Additionally, 24-h memory improved considerably during the discrimination task, compared with absolute association (15-55%). We found that antennal amputation was unnecessary and reduced performance in AHBs. Thus color learning can now be studied using the PER protocol with intact AHBs. This finding opens the way towards investigating visual and multimodal learning with application of neural techniques commonly used in restrained honey bees.

Long-term control of olfactory neuroblastoma in a dog treated with surgery and radiation therapy.

PubMed

Gumpel, E; Moore, A S; Simpson, D J; Hoffmann, K L; Taylor, D P

2017-07-01

Olfactory neuroblastoma is a rare malignancy of the nasal cavity in dogs that is thought to arise from specialised sensory neuroendocrine olfactory cells derived from the neural crest. An 8-year-old dog was presented for reclusiveness and pacing. On CT and MRI, a contract-enhancing mass was disclosed within the rostral fossa, extending caudally from the cribriform plate into the left nasal sinus. Surgical excision was performed and the diagnosis was histological grade III (Hyams grading scheme) olfactory neuroblastoma. Based on human CT criteria this was high stage (modified Kadish stage C). Surgical excision was incomplete and was followed by curative-intent radiation therapy using a linear accelerator to a total dose of 48 Gy. The dog survived 20 months after diagnosis. Although olfactory neuroblastoma is a rare tumour in dogs, aggressive local therapy may allow for prolonged survival, even when the tumour is advanced. © 2017 Australian Veterinary Association.

Early olfactory environment influences social behaviour in adult Octodon degus.

PubMed

Márquez, Natalia; Martínez-Harms, Jaime; Vásquez, Rodrigo A; Mpodozis, Jorge

2015-01-01

We evaluated the extent to which manipulation of early olfactory environment can influence social behaviours in the South American Hystricognath rodent Octodon degus. The early olfactory environment of newborn degus was manipulated by scenting all litter members with eucalyptol during the first month of life. The social behaviour of sexually mature animals (5-7 months old) towards conspecifics was then assessed using a y-maze to compare the response of control (naïve) and treated animals to two different olfactory configurations (experiment 1): (i) a non-familiarized conspecific impregnated with eucalyptol (eucalyptol arm) presented against (ii) a non-familiarized unscented conspecific (control arm). In addition, in dyadic encounters, we assessed the behaviour of control and eucalyptol treated animals towards a non-familiarized conspecific scented with eucalyptol (experiment 2). We found that control subjects explored and spent significantly less time in the eucalyptol arm, indicating neophobic behaviours towards the artificially scented conspecific. Treated subjects explored and spent similar time in both arms of the maze, showing the same interest for both olfactory stimuli presented. During dyadic encounters in experiment 2, an interaction effect between early experience and sex was observed. Control males escaped and avoided their scented partner more frequently than eucalyptol treated male subjects and than females. Both groups did not differ in the exploration of their scented partners, suggesting that avoidance within agonistic context does not relate to neophobic behaviours. Our results suggest that the exposure to eucalyptol during early ontogeny decreases evasive behaviours within an agonistic context as a result of olfactory learning. Altogether, these results indicate that olfactory cues learned in early ontogeny can influence olfactory-guided behaviours in adult degus.

Effects of diversity in olfactory environment on children's sense of smell.

PubMed

Martinec Nováková, Lenka; Fialová, Jitka; Havlíček, Jan

2018-02-13

Diversity in children's everyday olfactory environment may affect the development of their olfactory abilities and odor awareness. To test this, we collected data on olfactory abilities using the Sniffin' Sticks and odor awareness with Children's Olfactory Behaviors in Everyday Life Questionnaire in 153 preschool children and retested them one and a half year later. Parents completed an inventory on children's exposure to a variety of odors and on their own odor awareness using the Odor Awareness Scale. We controlled for the effects of age and verbal fluency on the children's performance. We found that the children's odor identification and discrimination scores differed as a function of parental odor awareness. Although these effects were rather small, they were commensurate in size with those of gender and age. To the best of our knowledge, this study is the first to present evidence that diversity in children's olfactory environment affects variation in their olfactory abilities and odor awareness. We suggest that future studies consider the long-term impact of perceptual learning out of the laboratory and its consequences for olfactory development.

Effects of field-realistic doses of glyphosate on honeybee appetitive behaviour.

PubMed

Herbert, Lucila T; Vázquez, Diego E; Arenas, Andrés; Farina, Walter M

2014-10-01

Glyphosate (GLY) is a broad-spectrum herbicide used for weed control. The sub-lethal impact of GLY on non-target organisms such as insect pollinators has not yet been evaluated. Apis mellifera is the main pollinator in agricultural environments and is a well-known model for behavioural research. Honeybees are also accurate biosensors of environmental pollutants and their appetitive behavioural response is a suitable tool with which to test sub-lethal effects of agrochemicals. We studied the effects of field-realistic doses of GLY on honeybees exposed chronically or acutely to the herbicide. We focused on sucrose sensitivity, elemental and non-elemental associative olfactory conditioning of the proboscis extension response (PER), and foraging-related behaviour. We found a reduced sensitivity to sucrose and learning performance for the groups chronically exposed to GLY concentrations within the range of recommended doses. When olfactory PER conditioning was performed with sucrose reward with the same GLY concentrations (acute exposure), elemental learning and short-term memory retention decreased significantly compared with controls. Non-elemental associative learning was also impaired by an acute exposure to GLY traces. Altogether, these results imply that GLY at concentrations found in agro-ecosystems as a result of standard spraying can reduce sensitivity to nectar reward and impair associative learning in honeybees. However, no effect on foraging-related behaviour was found. Therefore, we speculate that successful forager bees could become a source of constant inflow of nectar with GLY traces that could then be distributed among nestmates, stored in the hive and have long-term negative consequences on colony performance. © 2014. Published by The Company of Biologists Ltd.

Odor Learning and Its Experience-Dependent Modulation in the South American Native Bumblebee Bombus atratus (Hymenoptera: Apidae).

PubMed

Palottini, Florencia; Estravis Barcala, María C; Farina, Walter M

2018-01-01

Learning about olfactory stimuli is essential in bumblebees' life since it is involved in orientation, recognition of nest sites, foraging efficiency and food yield for the colony as a whole. To evaluate associative learning abilities in bees under controlled environmental conditions, the proboscis extension response (PER) assay is a well-established method used in honey bees, stingless bees and successfully adapted to bumblebees of the genus Bombus . However, studies on the learning capacity of Bombus atratus (Hymenoptera: Apidae), one of the most abundant native species in South America, are non-existent. In this study, we examined the cognitive abilities of worker bees of this species, carrying out an olfactory PER conditioning experiment. Bumblebees were able to learn a pure odor when it was presented in paired association with sugared reward, but not when odor and reward were presented in an unpaired manner. Furthermore, if the bees were preexposed to the conditioned odor, the results differed depending on the presence of the scent either as a volatile in the rearing environment or diluted in the food. A decrement in learning performance results from the non-reinforced pre-exposure to the to-be-conditioned odor, showing a latent inhibition phenomenon. However, if the conditioned odor has been previously offered diluted in sugared reward, the food odor acts as a stimulus that improves the learning performance during PER conditioning. The native bumblebee B. atratus is thus a new hymenopteran species capable of being trained under controlled experimental conditions. Since it is an insect increasingly reared for pollination service, this knowledge could be useful in its management in crops.

Odor Learning and Its Experience-Dependent Modulation in the South American Native Bumblebee Bombus atratus (Hymenoptera: Apidae)

PubMed Central

Palottini, Florencia; Estravis Barcala, María C.; Farina, Walter M.

2018-01-01

Learning about olfactory stimuli is essential in bumblebees’ life since it is involved in orientation, recognition of nest sites, foraging efficiency and food yield for the colony as a whole. To evaluate associative learning abilities in bees under controlled environmental conditions, the proboscis extension response (PER) assay is a well-established method used in honey bees, stingless bees and successfully adapted to bumblebees of the genus Bombus. However, studies on the learning capacity of Bombus atratus (Hymenoptera: Apidae), one of the most abundant native species in South America, are non-existent. In this study, we examined the cognitive abilities of worker bees of this species, carrying out an olfactory PER conditioning experiment. Bumblebees were able to learn a pure odor when it was presented in paired association with sugared reward, but not when odor and reward were presented in an unpaired manner. Furthermore, if the bees were preexposed to the conditioned odor, the results differed depending on the presence of the scent either as a volatile in the rearing environment or diluted in the food. A decrement in learning performance results from the non-reinforced pre-exposure to the to-be-conditioned odor, showing a latent inhibition phenomenon. However, if the conditioned odor has been previously offered diluted in sugared reward, the food odor acts as a stimulus that improves the learning performance during PER conditioning. The native bumblebee B. atratus is thus a new hymenopteran species capable of being trained under controlled experimental conditions. Since it is an insect increasingly reared for pollination service, this knowledge could be useful in its management in crops. PMID:29755391

Functional Neuroanatomy of "Drosophila" Olfactory Memory Formation

ERIC Educational Resources Information Center

Guven-Ozkan, Tugba; Davis, Ronald L.

2014-01-01

New approaches, techniques and tools invented over the last decade and a half have revolutionized the functional dissection of neural circuitry underlying "Drosophila" learning. The new methodologies have been used aggressively by researchers attempting to answer three critical questions about olfactory memories formed with appetitive…

The participation of cortical amygdala in innate, odour-driven behaviour.

PubMed

Root, Cory M; Denny, Christine A; Hen, René; Axel, Richard

2014-11-13

Innate behaviours are observed in naive animals without prior learning or experience, suggesting that the neural circuits that mediate these behaviours are genetically determined and stereotyped. The neural circuits that convey olfactory information from the sense organ to the cortical and subcortical olfactory centres have been anatomically defined, but the specific pathways responsible for innate responses to volatile odours have not been identified. Here we devise genetic strategies that demonstrate that a stereotyped neural circuit that transmits information from the olfactory bulb to cortical amygdala is necessary for innate aversive and appetitive behaviours. Moreover, we use the promoter of the activity-dependent gene arc to express the photosensitive ion channel, channelrhodopsin, in neurons of the cortical amygdala activated by odours that elicit innate behaviours. Optical activation of these neurons leads to appropriate behaviours that recapitulate the responses to innate odours. These data indicate that the cortical amygdala plays a critical role in generating innate odour-driven behaviours but do not preclude its participation in learned olfactory behaviours.

Teaching children with autism spectrum disorder to tact olfactory stimuli.

PubMed

Dass, Tina K; Kisamore, April N; Vladescu, Jason C; Reeve, Kenneth F; Reeve, Sharon A; Taylor-Santa, Catherine

2018-05-28

Research on tact acquisition by children with autism spectrum disorder (ASD) has often focused on teaching participants to tact visual stimuli. It is important to evaluate procedures for teaching tacts of nonvisual stimuli (e.g., olfactory, tactile). The purpose of the current study was to extend the literature on secondary target instruction and tact training by evaluating the effects of a discrete-trial instruction procedure involving (a) echoic prompts, a constant prompt delay, and error correction for primary targets; (b) inclusion of secondary target stimuli in the consequent portion of learning trials; and (c) multiple exemplar training on the acquisition of item tacts of olfactory stimuli, emergence of category tacts of olfactory stimuli, generalization of category tacts, and emergence of category matching, with three children diagnosed with ASD. Results showed that all participants learned the item and category tacts following teaching, participants demonstrated generalization across category tacts, and category matching emerged for all participants. © 2018 Society for the Experimental Analysis of Behavior.

Differential Modifications of Synaptic Weights During Odor Rule Learning: Dynamics of Interaction Between the Piriform Cortex with Lower and Higher Brain Areas

PubMed Central

Cohen, Yaniv; Wilson, Donald A.; Barkai, Edi

2015-01-01

Learning of a complex olfactory discrimination (OD) task results in acquisition of rule learning after prolonged training. Previously, we demonstrated enhanced synaptic connectivity between the piriform cortex (PC) and its ascending and descending inputs from the olfactory bulb (OB) and orbitofrontal cortex (OFC) following OD rule learning. Here, using recordings of evoked field postsynaptic potentials in behaving animals, we examined the dynamics by which these synaptic pathways are modified during rule acquisition. We show profound differences in synaptic connectivity modulation between the 2 input sources. During rule acquisition, the ascending synaptic connectivity from the OB to the anterior and posterior PC is simultaneously enhanced. Furthermore, post-training stimulation of the OB enhanced learning rate dramatically. In sharp contrast, the synaptic input in the descending pathway from the OFC was significantly reduced until training completion. Once rule learning was established, the strength of synaptic connectivity in the 2 pathways resumed its pretraining values. We suggest that acquisition of olfactory rule learning requires a transient enhancement of ascending inputs to the PC, synchronized with a parallel decrease in the descending inputs. This combined short-lived modulation enables the PC network to reorganize in a manner that enables it to first acquire and then maintain the rule. PMID:23960200

Lateralization of Sucrose Responsiveness and Non-associative Learning in Honeybees

PubMed Central

Baracchi, David; Rigosi, Elisa; de Brito Sanchez, Gabriela; Giurfa, Martin

2018-01-01

Lateralization is a fundamental property of the human brain that affects perceptual, motor, and cognitive processes. It is now acknowledged that left–right laterality is widespread across vertebrates and even some invertebrates such as fruit flies and bees. Honeybees, which learn to associate an odorant (the conditioned stimulus, CS) with sucrose solution (the unconditioned stimulus, US), recall this association better when trained using their right antenna than they do when using their left antenna. Correspondingly, olfactory sensilla are more abundant on the right antenna and odor encoding by projection neurons of the right antennal lobe results in better odor differentiation than those of the left one. Thus, lateralization arises from asymmetries both in the peripheral and central olfactory system, responsible for detecting the CS. Here, we focused on the US component and studied if lateralization exists in the gustatory system of Apis mellifera. We investigated whether sucrose sensitivity is lateralized both at the level of the antennae and the fore-tarsi in two independent groups of bees. Sucrose sensitivity was assessed by presenting bees with a series of increasing concentrations of sucrose solution delivered either to the left or the right antenna/tarsus and measuring the proboscis extension response to these stimuli. Bees experienced two series of stimulations, one on the left and the other on the right antenna/tarsus. We found that tarsal responsiveness was similar on both sides and that the order of testing affects sucrose responsiveness. On the contrary, antennal responsiveness to sucrose was higher on the right than on the left side, and this effect was independent of the order of antennal stimulation. Given this asymmetry, we also investigated antennal lateralization of habituation to sucrose. We found that the right antenna was more resistant to habituation, which is consistent with its higher sucrose sensitivity. Our results reveal that the gustatory system presents a peripheral lateralization that affects stimulus detection and non-associative learning. Contrary to the olfactory system, which is organized in two distinct brain hemispheres, gustatory receptor neurons converge into a single central region termed the subesophagic zone (SEZ). Whether the SEZ presents lateralized gustatory processing remains to be determined. PMID:29643828

Development and Validation of a Food-Associated Olfactory Test (FAOT).

PubMed

Denzer-Lippmann, Melanie Yvonne; Beauchamp, Jonathan; Freiherr, Jessica; Thuerauf, Norbert; Kornhuber, Johannes; Buettner, Andrea

2017-01-01

Olfactory tests are an important tool in human nutritional research for studying food preferences, yet comprehensive tests dedicated solely to food odors are currently lacking. Therefore, within this study, an innovative food-associated olfactory test (FAOT) system was developed. The FAOT comprises 16 odorant pens that contain representative food odors relating to different macronutrient classes. The test underwent a sensory validation based on identification rate, intensity, hedonic value, and food association scores. The accuracy of the test was further compared to the accuracy of the established Sniffin' Sticks identification test. The identification rates and intensities of this new FAOT were found to be comparable to the Sniffin' Sticks olfactory identification test. The odorant pens were also assessed chemo-analytically and were found to be chemically stable for at least 24 weeks. Overall, this new identification test for use in assessing olfaction in a food-associated context is valid both in terms of its use in sensory perception studies and its chemical stability. The FOAT is particularly suited to examinations of the sense of smell regarding food odors. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sensory reception of the primer pheromone ethyl oleate

NASA Astrophysics Data System (ADS)

Muenz, Thomas S.; Maisonnasse, Alban; Plettner, Erika; Le Conte, Yves; Rössler, Wolfgang

2012-05-01

Social work force distribution in honeybee colonies critically depends on subtle adjustments of an age-related polyethism. Pheromones play a crucial role in adjusting physiological and behavioral maturation of nurse bees to foragers. In addition to primer effects of brood pheromone and queen mandibular pheromone—both were shown to influence onset of foraging—direct worker-worker interactions influence adult behavioral maturation. These interactions were narrowed down to the primer pheromone ethyl oleate, which is present at high concentrations in foragers, almost absent in young bees and was shown to delay the onset of foraging. Based on chemical analyses, physiological recordings from the antenna (electroantennograms) and the antennal lobe (calcium imaging), and behavioral assays (associative conditioning of the proboscis extension response), we present evidence that ethyl oleate is most abundant on the cuticle, received by olfactory receptors on the antenna, processed in glomeruli of the antennal lobe, and learned in olfactory centers of the brain. The results are highly suggestive that the primer pheromone ethyl oleate is transmitted and perceived between individuals via olfaction at close range.

Sucrose acceptance and different forms of associative learning of the honey bee (apis mellifera L.) in the field and laboratory.

PubMed

Mujagic, Samir; Sarkander, Jana; Erber, Barbara; Erber, Joachim

2010-01-01

The experiments analyze different forms of learning and 24-h retention in the field and in the laboratory in bees that accept sucrose with either low (/=30% or >/=50%) concentrations. In the field we studied color learning at a food site and at the hive entrance. In the laboratory olfactory conditioning of the proboscis extension response (PER) was examined. In the color learning protocol at a feeder, bees with low sucrose acceptance thresholds (/=50%). Retention after 24 h is significantly different between the two groups of bees and the choice reactions converge. Bees with low and high acceptance thresholds in the field show no differences in the sucrose sensitivity PER tests in the laboratory. Acceptance thresholds in the field are thus a more sensitive behavioral measure than PER responsiveness in the laboratory. Bees with low acceptance thresholds show significantly better acquisition and 24-h retention in olfactory learning in the laboratory compared to bees with high thresholds. In the learning protocol at the hive entrance bees learn without sucrose reward that a color cue signals an open entrance. In this experiment, bees with high sucrose acceptance thresholds showed significantly better learning and reversal learning than bees with low thresholds. These results demonstrate that sucrose acceptance thresholds affect only those forms of learning in which sucrose serves as the reward. The results also show that foraging behavior in the field is a good predictor for learning behavior in the field and in the laboratory.

Unirhinal Olfactory Testing for the Diagnostic Workup of Mild Cognitive Impairment.

PubMed

Huart, Caroline; Rombaux, Philippe; Gérard, Thomas; Hanseeuw, Bernard; Lhommel, Renaud; Quenon, Lisa; Ivanoiu, Adrian; Mouraux, André

2015-01-01

Olfactory dysfunction is associated with Alzheimer's disease (AD), and already present at pre-dementia stage. Based on the assumption that early neurodegeneration in AD is asymmetrical and that olfactory input is primarily processed in the ipsilateral hemisphere, we assessed whether unirhinal psychophysical and electrophysiological assessment of olfactory function can contribute to the diagnostic workup of mild cognitive impairment (MCI). Olfactory function of 13 MCI patients with positive amyloid PET, 13 aged-matched controls (AC) with negative amyloid PET and 13 patients with post-infectious olfactory loss (OD) was assessed unirhinally using (1) psychophysical testing of olfactory detection, discrimination and identification performance and (2) the recording of olfactory event-related brain potentials. Time-frequency analysis was used to enhance the signal-to-noise ratio of the electrophysiological responses. Psychophysical and electrophysiological assessment of auditory and trigeminal chemosensory function served as controls. As compared to AC and OD, MCI patients exhibited a significant asymmetry of olfactory performance. This asymmetry efficiently discriminated between MCI and AC (sensitivity: 85% , specificity: 77% ), as well as MCI and OD (sensitivity: 85% , specificity: 70% ). There was also an asymmetry of the electrophysiological responses, but not specific for MCI. In both MCI and OD, olfactory stimulation of the best nostril elicited significantly more activity than stimulation of the worse nostril, between 3-7.5 Hz and 1.2-2.0 s after stimulus onset. Trigeminal and auditory psychophysical testing did not show any difference between groups. MCI patients exhibit a marked asymmetry of behavioral olfactory function, which could be useful for the diagnostic workup of MCI.

Predictors of Olfactory Dysfunction in Rhinosinusitis Using the Brief Smell Identification Test

PubMed Central

Alt, Jeremiah A.; Mace, Jess C.; Buniel, Maria C. F.; Soler, Zachary M.; Smith, Timothy L.

2014-01-01

Objective Associations between olfactory function to quality-of-life (QOL) and disease severity in patients with rhinosinusitis is poorly understood. We sought to evaluate and compare olfactory function between subgroups of patients with rhinosinusitis using the Brief Smell Identification Test (BSIT). Study Design Cross-sectional evaluation of a multi-center cohort. Methods Patients with recurrent acute sinusitis (RARS) and chronic rhinosinusitis (CRS) with and without nasal polyposis were prospectively enrolled from three academic tertiary care sites. Each subject completed the BSIT, in addition to measures of disease-specific QOL. Patient demographics, comorbidities, and clinical measures of disease severity were compared between patients with normal (BSIT; ≥9) and abnormal (BSIT; <9) olfaction scores. Regression modeling was used to identify potential risk factors associated with olfactory impairment. Results Patients with rhinosinusitis (n=445) were found to suffer olfactory dysfunction as measured by the BSIT (28.3%). Subgroups of rhinosinusitis differed in the degree of olfactory dysfunction reported. Worse disease severity, measured by computed tomography and nasal endoscopy, correlated to worse olfaction. Olfactory scores did not consistently correlate with Rhinosinusitis Disability Index or Sinonasal Outcome Test scores. Regression models demonstrated nasal polyposis was the strongest predictor of olfactory dysfunction. Recalcitrant disease and aspirin intolerance were strongly predictive of worse olfactory function. Conclusion Olfactory dysfunction is a complex, multi-factorial process found to be differentially expressed within subgroups of rhinosinusitis. Olfaction was associated with disease severity as measured by imaging and endoscopy, with only weak associations to disease-specific QOL measures. PMID:24402746

Assessment of Olfactory Function in MAPT-Associated Neurodegenerative Disease Reveals Odor-Identification Irreproducibility as a Non-Disease-Specific, General Characteristic of Olfactory Dysfunction.

PubMed

Markopoulou, Katerina; Chase, Bruce A; Robowski, Piotr; Strongosky, Audrey; Narożańska, Ewa; Sitek, Emilia J; Berdynski, Mariusz; Barcikowska, Maria; Baker, Matt C; Rademakers, Rosa; Sławek, Jarosław; Klein, Christine; Hückelheim, Katja; Kasten, Meike; Wszolek, Zbigniew K

2016-01-01

Olfactory dysfunction is associated with normal aging, multiple neurodegenerative disorders, including Parkinson's disease, Lewy body disease and Alzheimer's disease, and other diseases such as diabetes, sleep apnea and the autoimmune disease myasthenia gravis. The wide spectrum of neurodegenerative disorders associated with olfactory dysfunction suggests different, potentially overlapping, underlying pathophysiologies. Studying olfactory dysfunction in presymptomatic carriers of mutations known to cause familial parkinsonism provides unique opportunities to understand the role of genetic factors, delineate the salient characteristics of the onset of olfactory dysfunction, and understand when it starts relative to motor and cognitive symptoms. We evaluated olfactory dysfunction in 28 carriers of two MAPT mutations (p.N279K, p.P301L), which cause frontotemporal dementia with parkinsonism, using the University of Pennsylvania Smell Identification Test. Olfactory dysfunction in carriers does not appear to be allele specific, but is strongly age-dependent and precedes symptomatic onset. Severe olfactory dysfunction, however, is not a fully penetrant trait at the time of symptom onset. Principal component analysis revealed that olfactory dysfunction is not odor-class specific, even though individual odor responses cluster kindred members according to genetic and disease status. Strikingly, carriers with incipient olfactory dysfunction show poor inter-test consistency among the sets of odors identified incorrectly in successive replicate tests, even before severe olfactory dysfunction appears. Furthermore, when 78 individuals without neurodegenerative disease and 14 individuals with sporadic Parkinson's disease were evaluated twice at a one-year interval using the Brief Smell Identification Test, the majority also showed inconsistency in the sets of odors they identified incorrectly, independent of age and cognitive status. While these findings may reflect the limitations of these tests used and the sample sizes, olfactory dysfunction appears to be associated with the inability to identify odors reliably and consistently, not with the loss of an ability to identify specific odors. Irreproducibility in odor identification appears to be a non-disease-specific, general feature of olfactory dysfunction that is accelerated or accentuated in neurodegenerative disease. It may reflect a fundamental organizational principle of the olfactory system, which is more "error-prone" than other sensory systems.

Impaired associative learning after chronic exposure to pesticides in young adult honey bees.

PubMed

Mengoni Goñalons, Carolina; Farina, Walter M

2018-04-11

Neonicotinoids are the most widespread insecticides in agriculture, preferred for their low toxicity to mammals and their systemic nature. Nevertheless, there have been increasing concerns regarding their impact on non-target organisms. Glyphosate is also widely used in crops and, therefore, traces of this pesticide are likely to be found together with neonicotinoids. Although glyphosate is considered a herbicide, adverse effects have been found on animal species, including honey bees. Apis mellifera is one of the most important pollinators in agroecosystems and is exposed to both these pesticides. Traces can be found in nectar and pollen of flowers that honey bees visit, but also in honey stores inside the hive. Young workers, which perform in-hive tasks that are crucial for colony maintenance, are potentially exposed to both these contaminated resources. These workers present high plasticity and are susceptible to stimuli that can modulate their behaviour and impact on colony state. Therefore, by performing standardised assays to study sublethal effects of these pesticides, these bees can be used as bioindicators. We studied the effect of chronic joint exposure to field-realistic concentrations of the neonicotinoid imidacloprid and glyphosate on gustatory perception and olfactory learning. Both pesticides reduced sucrose responsiveness and had a negative effect on olfactory learning. Glyphosate also reduced food uptake during rearing. The results indicate differential susceptibility according to honey bee age. The two agrochemicals had adverse effects on different aspects of honey bee appetitive behaviour, which could have repercussions for food distribution, propagation of olfactory information and task coordination within the nest. © 2018. Published by The Company of Biologists Ltd.

It takes two-coincidence coding within the dual olfactory pathway of the honeybee.

PubMed

Brill, Martin F; Meyer, Anneke; Rössler, Wolfgang

2015-01-01

To rapidly process biologically relevant stimuli, sensory systems have developed a broad variety of coding mechanisms like parallel processing and coincidence detection. Parallel processing (e.g., in the visual system), increases both computational capacity and processing speed by simultaneously coding different aspects of the same stimulus. Coincidence detection is an efficient way to integrate information from different sources. Coincidence has been shown to promote associative learning and memory or stimulus feature detection (e.g., in auditory delay lines). Within the dual olfactory pathway of the honeybee both of these mechanisms might be implemented by uniglomerular projection neurons (PNs) that transfer information from the primary olfactory centers, the antennal lobe (AL), to a multimodal integration center, the mushroom body (MB). PNs from anatomically distinct tracts respond to the same stimulus space, but have different physiological properties, characteristics that are prerequisites for parallel processing of different stimulus aspects. However, the PN pathways also display mirror-imaged like anatomical trajectories that resemble neuronal coincidence detectors as known from auditory delay lines. To investigate temporal processing of olfactory information, we recorded PN odor responses simultaneously from both tracts and measured coincident activity of PNs within and between tracts. Our results show that coincidence levels are different within each of the two tracts. Coincidence also occurs between tracts, but to a minor extent compared to coincidence within tracts. Taken together our findings support the relevance of spike timing in coding of olfactory information (temporal code).

Distinct Neural Mechanisms Mediate Olfactory Memory Formation at Different Timescales

ERIC Educational Resources Information Center

McNamara, Ann Marie; Magidson, Phillip D.; Linster, Christiane; Wilson, Donald A.; Cleland, Thomas A.

2008-01-01

Habituation is one of the oldest forms of learning, broadly expressed across sensory systems and taxa. Here, we demonstrate that olfactory habituation induced at different timescales (comprising different odor exposure and intertrial interval durations) is mediated by different neural mechanisms. First, the persistence of habituation memory is…

Coral reef fish smell leaves to find island homes.

PubMed

Dixson, Danielle L; Jones, Geoffrey P; Munday, Philip L; Planes, Serge; Pratchett, Morgan S; Srinivasan, Maya; Syms, Craig; Thorrold, Simon R

2008-12-22

Recent studies have shown that some coral reef fish larvae return to natal reefs, while others disperse to distant reefs. However, the sensory mechanisms used to find settlement sites are poorly understood. One hypothesis is that larvae use olfactory cues to navigate home or find other suitable reef habitats. Here we show a strong association between the clownfish Amphiprion percula and coral reefs surrounding offshore islands in Papua New Guinea. Host anemones and A. percula are particularly abundant in shallow water beneath overhanging rainforest vegetation. A series of experiments were carried out using paired-choice flumes to evaluate the potential role of water-borne olfactory cues in finding islands. Recently settled A. percula exhibited strong preferences for: (i) water from reefs with islands over water from reefs without islands; (ii) water collected near islands over water collected offshore; and (iii) water treated with either anemones or leaves from rainforest vegetation. Laboratory reared-juveniles exhibited the same positive response to anemones and rainforest vegetation, suggesting that olfactory preferences are innate rather than learned. We hypothesize that A. percula use a suite of olfactory stimuli to locate vegetated islands, which may explain the high levels of self-recruitment on island reefs. This previously unrecognized link between coral reefs and island vegetation argues for the integrated management of these pristine tropical habitats.

Coral reef fish smell leaves to find island homes

PubMed Central

Dixson, Danielle L; Jones, Geoffrey P; Munday, Philip L; Planes, Serge; Pratchett, Morgan S; Srinivasan, Maya; Syms, Craig; Thorrold, Simon R

2008-01-01

Recent studies have shown that some coral reef fish larvae return to natal reefs, while others disperse to distant reefs. However, the sensory mechanisms used to find settlement sites are poorly understood. One hypothesis is that larvae use olfactory cues to navigate home or find other suitable reef habitats. Here we show a strong association between the clownfish Amphiprion percula and coral reefs surrounding offshore islands in Papua New Guinea. Host anemones and A. percula are particularly abundant in shallow water beneath overhanging rainforest vegetation. A series of experiments were carried out using paired-choice flumes to evaluate the potential role of water-borne olfactory cues in finding islands. Recently settled A. percula exhibited strong preferences for: (i) water from reefs with islands over water from reefs without islands; (ii) water collected near islands over water collected offshore; and (iii) water treated with either anemones or leaves from rainforest vegetation. Laboratory reared-juveniles exhibited the same positive response to anemones and rainforest vegetation, suggesting that olfactory preferences are innate rather than learned. We hypothesize that A. percula use a suite of olfactory stimuli to locate vegetated islands, which may explain the high levels of self-recruitment on island reefs. This previously unrecognized link between coral reefs and island vegetation argues for the integrated management of these pristine tropical habitats. PMID:18755672

Behavioral consequences of innate preferences and olfactory learning in hawkmoth–flower interactions

PubMed Central

Riffell, Jeffrey A.; Alarcón, Ruben; Abrell, Leif; Davidowitz, Goggy; Bronstein, Judith L.; Hildebrand, John G.

2008-01-01

Spatiotemporal variability in floral resources can have ecological and evolutionary consequences for both plants and the pollinators on which they depend. Seldom, however, can patterns of flower abundance and visitation in the field be linked with the behavioral mechanisms that allow floral visitors to persist when a preferred resource is scarce. To explore these mechanisms better, we examined factors controlling floral preference in the hawkmoth Manduca sexta in the semiarid grassland of Arizona. Here, hawkmoths forage primarily on flowers of the bat-adapted agave, Agave palmeri, but shift to the moth-adapted flowers of their larval host plant, Datura wrightii, when these become abundant. Both plants emit similar concentrations of floral odor, but scent composition, nectar, and flower reflectance are distinct between the two species, and A. palmeri flowers provide six times as much chemical energy as flowers of D. wrightii. Behavioral experiments with both naïve and experienced moths revealed that hawkmoths learn to feed from agave flowers through olfactory conditioning but readily switch to D. wrightii flowers, for which they are the primary pollinator, based on an innate odor preference. Behavioral flexibility and the olfactory contrast between flowers permit the hawkmoths to persist within a dynamic environment, while at the same time to function as the major pollinator of one plant species. PMID:18305169

Selection for associative learning of colour stimuli reveals correlated evolution of this learning ability across multiple stimuli and rewards.

PubMed

Liefting, Maartje; Hoedjes, Katja M; Lann, Cécile Le; Smid, Hans M; Ellers, Jacintha

2018-05-16

We are only starting to understand how variation in cognitive ability can result from local adaptations to environmental conditions. A major question in this regard is to what extent selection on cognitive ability in a specific context affects that ability in general through correlated evolution. To address this question we performed artificial selection on visual associative learning in female Nasonia vitripennis wasps. Using appetitive conditioning in which a visual stimulus was offered in association with a host reward, the ability to learn visual associations was enhanced within 10 generations of selection. To test for correlated evolution affecting this form of learning, the ability to readily form learned associations in females was also tested using an olfactory instead of a visual stimulus in the appetitive conditioning. Additionally, we assessed whether the improved associative learning ability was expressed across sexes by colour-conditioning males with a mating reward. Both females and males from the selected lines consistently demonstrated an increased associative learning ability compared to the control lines, independent of learning context or conditioned stimulus. No difference in relative volume of brain neuropils was detected between the selected and control lines. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing

PubMed Central

Frederick, Donald E.; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark

2016-01-01

Olfactory system beta (15–35 Hz) and gamma (40–110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test whether beta and gamma oscillations represent different cognitive modes using the different demands of go/no-go and two-alternative choice tasks that previously were suggested to favor beta or gamma oscillations, respectively. We reconcile previous studies and show that both beta and gamma oscillations occur in both tasks, with gamma dominating the early odor sampling period (2–4 sniffs) and beta dominating later. The relative power and coherence of both oscillations depend separately on multiple factors within both tasks without categorical differences across tasks. While the early/gamma-associated period occurs in all trials, rats can perform above chance without the later/beta-associated period. Longer sampling, which includes beta oscillations, is associated with better performance. Gamma followed by beta oscillations therefore represents a sequence of cognitive and neural states during odor discrimination, which can be separately modified depending on the demands of a task and odor discrimination. Additionally, fast (85 Hz) and slow (70 Hz) olfactory bulb gamma oscillation sub-bands have been hypothesized to represent tufted and mitral cell networks, respectively (Manabe and Mori, 2013). We find that fast gamma favors the early and slow gamma the later (beta-dominated) odor-sampling period and that the relative contributions of these oscillations are consistent across tasks. SIGNIFICANCE STATEMENT Olfactory system gamma (40–110 Hz) and beta (15–35 Hz) oscillations of the local field potential indicate different neural firing statistics and functional circuits. We show that gamma and beta oscillations occur in stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. PMID:27445151

Gamma and Beta Oscillations Define a Sequence of Neurocognitive Modes Present in Odor Processing.

PubMed

Frederick, Donald E; Brown, Austin; Brim, Elizabeth; Mehta, Nisarg; Vujovic, Mark; Kay, Leslie M

2016-07-20

Olfactory system beta (15-35 Hz) and gamma (40-110 Hz) oscillations of the local field potential in mammals have both been linked to odor learning and discrimination. Gamma oscillations represent the activity of a local network within the olfactory bulb, and beta oscillations represent engagement of a systemwide network. Here, we test whether beta and gamma oscillations represent different cognitive modes using the different demands of go/no-go and two-alternative choice tasks that previously were suggested to favor beta or gamma oscillations, respectively. We reconcile previous studies and show that both beta and gamma oscillations occur in both tasks, with gamma dominating the early odor sampling period (2-4 sniffs) and beta dominating later. The relative power and coherence of both oscillations depend separately on multiple factors within both tasks without categorical differences across tasks. While the early/gamma-associated period occurs in all trials, rats can perform above chance without the later/beta-associated period. Longer sampling, which includes beta oscillations, is associated with better performance. Gamma followed by beta oscillations therefore represents a sequence of cognitive and neural states during odor discrimination, which can be separately modified depending on the demands of a task and odor discrimination. Additionally, fast (85 Hz) and slow (70 Hz) olfactory bulb gamma oscillation sub-bands have been hypothesized to represent tufted and mitral cell networks, respectively (Manabe and Mori, 2013). We find that fast gamma favors the early and slow gamma the later (beta-dominated) odor-sampling period and that the relative contributions of these oscillations are consistent across tasks. Olfactory system gamma (40-110 Hz) and beta (15-35 Hz) oscillations of the local field potential indicate different neural firing statistics and functional circuits. We show that gamma and beta oscillations occur in stereotyped sequence during odor sampling in associative tasks, with local gamma dominating the first 250 ms of odor sniffing, followed by systemwide beta as behavioral responses are prepared. Oscillations and coupling strength between brain regions are modulated by task, odor, and learning, showing that task features can dramatically adjust the dynamics of a cortical sensory system, which changes state every ∼250 ms. Understanding cortical circuits, even at the biophysical level, depends on careful use of multiple behavioral contexts and stimuli. Copyright © 2016 the authors 0270-6474/16/367750-18$15.00/0.

Combinatorial Codes and Labeled Lines: How Insects Use Olfactory Cues to Find and Judge Food, Mates, and Oviposition Sites in Complex Environments

PubMed Central

Haverkamp, Alexander; Hansson, Bill S.; Knaden, Markus

2018-01-01

Insects, including those which provide vital ecosystems services as well as those which are devastating pests or disease vectors, locate their resources mainly based on olfaction. Understanding insect olfaction not only from a neurobiological but also from an ecological perspective is therefore crucial to balance insect control and conservation. However, among all sensory stimuli olfaction is particularly hard to grasp. Our chemical environment is made up of thousands of different compounds, which might again be detected by our nose in multiple ways. Due to this complexity, researchers have only recently begun to explore the chemosensory ecology of model organisms such as Drosophila, linking the tools of chemical ecology to those of neurogenetics. This cross-disciplinary approach has enabled several studies that range from single odors and their ecological relevance, via olfactory receptor genes and neuronal processing, up to the insects' behavior. We learned that the insect olfactory system employs strategies of combinatorial coding to process general odors as well as labeled lines for specific compounds that call for an immediate response. These studies opened new doors to the olfactory world in which insects feed, oviposit, and mate. PMID:29449815

Olfactory-triggered panic attacks among Khmer refugees: a contextual approach.

PubMed

Hinton, Devon; Pich, Vuth; Chhean, Dara; Pollack, Mark

2004-06-01

One hundred Khmer refugees attending a psychiatric clinic were surveyed to determine the prevalence of olfactory-triggered panic attacks as well as certain characteristics of the episodes, including trigger (i.e. type of odor), frequency, length, somatic symptoms, and the rate of associated flashbacks and catastrophic cognitions. Forty-five of the 100 patients had experienced an olfactory-triggered panic attack in the last month. Trauma associations and catastrophic cognitions (e.g. fears of a 'wind attack', 'weakness', and 'weak heart') were common during events of olfactory panic. Several case examples are presented. A multifactorial model of the generation of olfactory panic is adduced. The therapeutic implications of this model for the treatment of olfactory panic are discussed.

Prevalence of olfactory impairment in older adults.

PubMed

Murphy, Claire; Schubert, Carla R; Cruickshanks, Karen J; Klein, Barbara E K; Klein, Ronald; Nondahl, David M

2002-11-13

Older adults represent the fastest-growing segment of the US population, and prevalences of vision and hearing impairment have been extensively evaluated. However, despite the importance of sense of smell for nutrition and safety, the prevalence of olfactory impairment in older US adults has not been studied. To determine the prevalence of olfactory impairment in older adults. A total of 2491 Beaver Dam, Wis, residents aged 53 to 97 years participating in the 5-year follow-up examination (1998-2000) for the Epidemiology of Hearing Loss Study, a population-based, cross-sectional study. Olfactory impairment, assessed by the San Diego Odor Identification Test and self-report. The mean (SD) prevalence of impaired olfaction was 24.5% (1.7%). The prevalence increased with age; 62.5% (95% confidence interval [CI], 57.4%-67.7%) of 80- to 97-year-olds had olfactory impairment. Olfactory impairment was more prevalent among men (adjusted prevalence ratio, 1.92; 95% CI, 1.65-2.19). Current smoking, stroke, epilepsy, and nasal congestion or upper respiratory tract infection were also associated with increased prevalence of olfactory impairment. Self-reported olfactory impairment was low (9.5%) and this measure became less accurate with age. In the oldest group, aged 80 to 97 years, sensitivity of self-report was 12% for women and 18% for men. This study demonstrates that prevalence of olfactory impairment among older adults is high and increases with age. Self-report significantly underestimated prevalence rates obtained by olfaction testing. Physicians and caregivers should be particularly alert to the potential for olfactory impairment in the elderly population.

Directional coupling from the olfactory bulb to the hippocampus during a go/no-go odor discrimination task.

PubMed

Gourévitch, Boris; Kay, Leslie M; Martin, Claire

2010-05-01

The hippocampus and olfactory regions are anatomically close, and both play a major role in memory formation. However, the way they interact during odor processing is still unclear. In both areas, strong oscillations of the local field potential (LFP) can be recorded, and are modulated by behavior. In particular, in the olfactory system, the beta rhythm (15-35 Hz) is associated with cognitive processing of an olfactory stimulus. Using LFP recordings in the olfactory bulb and dorsal and ventral hippocampus during performance of an olfactory go/no-go task in rats, we previously showed that beta oscillations are also present in the hippocampus, coherent with those in the olfactory bulb, during odor sampling. In this study, we provide further insight into information transfer in the olfacto-hippocampal network by using directional coherence (DCOH estimate), a method based on the temporal relation between two or more signals in the frequency domain. In the theta band (6-12 Hz), coherence between the olfactory bulb (OB) and the hippocampus (HPC) is weak and can be both in the feedback and feedforward directions. However, at this frequency, modulation of the coupling between the dorsal and ventral hippocampus is seen during stimulus expectation versus odor processing. In the beta frequency band (15-35 Hz), analysis showed a strong unidirectional coupling from the OB to dorsal and ventral HPC, indicating that, during odor processing, beta oscillations in the hippocampus are driven by the olfactory bulb.

Experience during early adulthood shapes the learning capacities and the number of synaptic boutons in the mushroom bodies of honey bees (Apis mellifera).

PubMed

Cabirol, Amélie; Brooks, Rufus; Groh, Claudia; Barron, Andrew B; Devaud, Jean-Marc

2017-10-01

The honey bee mushroom bodies (MBs) are brain centers required for specific learning tasks. Here, we show that environmental conditions experienced as young adults affect the maturation of MB neuropil and performance in a MB-dependent learning task. Specifically, olfactory reversal learning was selectively impaired following early exposure to an impoverished environment lacking some of the sensory and social interactions present in the hive. In parallel, the overall number of synaptic boutons increased within the MB olfactory neuropil, whose volume remained unaffected. This suggests that experience of the rich in-hive environment promotes MB maturation and the development of MB-dependent learning capacities. © 2017 Cabirol et al.; Published by Cold Spring Harbor Laboratory Press.

Decoding an olfactory mechanism of kin recognition and inbreeding avoidance in a primate.

PubMed

Boulet, Marylène; Charpentier, Marie J E; Drea, Christine M

2009-12-03

Like other vertebrates, primates recognize their relatives, primarily to minimize inbreeding, but also to facilitate nepotism. Although associative, social learning is typically credited for discrimination of familiar kin, discrimination of unfamiliar kin remains unexplained. As sex-biased dispersal in long-lived species cannot consistently prevent encounters between unfamiliar kin, inbreeding remains a threat and mechanisms to avoid it beg explanation. Using a molecular approach that combined analyses of biochemical and microsatellite markers in 17 female and 19 male ring-tailed lemurs (Lemur catta), we describe odor-gene covariance to establish the feasibility of olfactory-mediated kin recognition. Despite derivation from different genital glands, labial and scrotal secretions shared about 170 of their respective 338 and 203 semiochemicals. In addition, these semiochemicals encoded information about genetic relatedness within and between the sexes. Although the sexes showed opposite seasonal patterns in signal complexity, the odor profiles of related individuals (whether same-sex or mixed-sex dyads) converged most strongly in the competitive breeding season. Thus, a strong, mutual olfactory signal of genetic relatedness appeared specifically when such information would be crucial for preventing inbreeding. That weaker signals of genetic relatedness might exist year round could provide a mechanism to explain nepotism between unfamiliar kin. We suggest that signal convergence between the sexes may reflect strong selective pressures on kin recognition, whereas signal convergence within the sexes may arise as its by-product or function independently to prevent competition between unfamiliar relatives. The link between an individual's genome and its olfactory signals could be mediated by biosynthetic pathways producing polymorphic semiochemicals or by carrier proteins modifying the individual bouquet of olfactory cues. In conclusion, we unveil a possible olfactory mechanism of kin recognition that has specific relevance to understanding inbreeding avoidance and nepotistic behavior observed in free-ranging primates, and broader relevance to understanding the mechanisms of vertebrate olfactory communication.

Olfactory Blocking and Odorant Similarity in the Honeybee

ERIC Educational Resources Information Center

Gerber, Bertram; Giurfa, Martin; Guerrieri, Fernando; Lachnit, Harald

2005-01-01

Blocking occurs when previous training with a stimulus A reduces (blocks) subsequent learning about a stimulus B, when A and B are trained in compound. The question of whether blocking exists in olfactory conditioning of proboscis extension reflex (PER) in honeybees is under debate. The last published accounts on blocking in honeybees state that…

Kinase Activity in the Olfactory Bulb Is Required for Odor Memory Consolidation

ERIC Educational Resources Information Center

Tong, Michelle T.; Kim, Tae-Young P.; Cleland, Thomas A.

2018-01-01

Long-term fear memory formation in the hippocampus and neocortex depends upon brain-derived neurotrophic factor (BDNF) signaling after acquisition. Incremental, appetitive odor discrimination learning is thought to depend substantially on the differentiation of adult-born neurons within the olfactory bulb (OB)--a process that is closely associated…

Neonicotinoid-induced impairment of odour coding in the honeybee

PubMed Central

Andrione, Mara; Vallortigara, Giorgio; Antolini, Renzo; Haase, Albrecht

2016-01-01

Exposure to neonicotinoid pesticides is considered one of the possible causes of honeybee (Apis mellifera) population decline. At sublethal doses, these chemicals have been shown to negatively affect a number of behaviours, including performance of olfactory learning and memory, due to their interference with acetylcholine signalling in the mushroom bodies. Here we provide evidence that neonicotinoids can affect odour coding upstream of the mushroom bodies, in the first odour processing centres of the honeybee brain, i.e. the antennal lobes (ALs). In particular, we investigated the effects of imidacloprid, the most common neonicotinoid, in the AL glomeruli via in vivo two-photon calcium imaging combined with pulsed odour stimulation. Following acute imidacloprid treatment, odour-evoked calcium response amplitude in single glomeruli decreases, and at the network level the representations of different odours are no longer separated. This demonstrates that, under neonicotinoid influence, olfactory information might reach the mushroom bodies in a form that is already incorrect. Thus, some of the impairments in olfactory learning and memory caused by neonicotinoids could, in fact, arise from the disruption in odor coding and olfactory discrimination ability of the honey bees. PMID:27905515

The participation of cortical amygdala in innate, odor-driven behavior

PubMed Central

Root, Cory M.; Denny, Christine A.; Hen, René; Axel, Richard

2014-01-01

Innate behaviors are observed in naïve animals without prior learning or experience, suggesting that the neural circuits that mediate these behaviors are genetically determined and stereotyped. The neural circuits that convey olfactory information from the sense organ to the cortical and subcortical olfactory centers have been anatomically defined1-3 but the specific pathways responsible for innate responses to volatile odors have not been identified. We have devised genetic strategies that demonstrate that a stereotyped neural circuit that transmits information from the olfactory bulb to cortical amygdala is necessary for innate aversive and appetitive behaviors. Moreover, we have employed the promoter of the activity-dependent gene, arc, to express the photosensitive ion channel, channelrhodopsin, in neurons of the cortical amygdala activated by odors that elicit innate behaviors. Optical activation of these neurons leads to appropriate behaviors that recapitulate the responses to innate odors. These data indicate that the cortical amygdala plays a critical role in the generation of innate odor-driven behaviors but do not preclude the participation of cortical amygdala in learned olfactory behaviors. PMID:25383519

Role of Nrf2 antioxidant defense in mitigating cadmium-induced oxidative stress in the olfactory system of zebrafish

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Lu; Gallagher, Evan P., E-mail: evang3@uw.edu

2013-01-15

Exposure to trace metals can disrupt olfactory function in fish leading to a loss of behaviors critical to survival. Cadmium (Cd) is an olfactory toxicant that elicits cellular oxidative stress as a mechanism of toxicity while also inducing protective cellular antioxidant genes via activation of the nuclear factor (erythroid-derived 2)-like 2 (Nrf2) pathway. However, the molecular mechanisms of Cd-induced olfactory injury have not been characterized. In the present study, we investigated the role of the Nrf2-mediated antioxidant defense pathway in protecting against Cd-induced olfactory injury in zebrafish. A dose-dependent induction of Nrf2-regulated antioxidant genes associated with cellular responses to oxidativemore » stress was observed in the olfactory system of adult zebrafish following 24 h Cd exposure. Zebrafish larvae exposed to Cd for 3 h showed increased glutathione S-transferase pi (gst pi), glutamate–cysteine ligase catalytic subunit (gclc), heme oxygenase 1 (hmox1) and peroxiredoxin 1 (prdx1) mRNA levels indicative of Nrf2 activation, and which were blocked by morpholino-mediated Nrf2 knockdown. The inhibition of antioxidant gene induction in Cd-exposed Nrf2 morphants was associated with disruption of olfactory driven behaviors, increased cell death and loss of olfactory sensory neurons (OSNs). Nrf2 morphants also exhibited a downregulation of OSN-specific genes after Cd exposure. Pre-incubation of embryos with sulforaphane (SFN) partially protected against Cd-induced olfactory tissue damage. Collectively, our results indicate that oxidative stress is an important mechanism of Cd-mediated injury in the zebrafish olfactory system. Moreover, the Nrf2 pathway plays a protective role against cellular oxidative damage and is important in maintaining zebrafish olfactory function. -- Highlights: ► Oxidative stress is an important mechanism of Cd-mediated olfactory injury. ► Cd induces antioxidant gene expression in the zebrafish olfactory system. ► The olfactory antioxidant response is blocked by Nrf2 knockdown. ► Disruption of olfactory neurobehaviors is associated with Nrf2 knockdown. ► Nrf2 morphants show increased cell death and olfactory sensory neuron loss.« less

Olfactory-Triggered Panic Attacks Among Khmer Refugees: A Contextual Approach

PubMed Central

Hinton, Devon; Pich, Vuth; Chhean, Dara; Pollack, Mark

2009-01-01

One hundred Khmer refugees attending a psychiatric clinic were surveyed to determine the prevalence of olfactory-triggered panic attacks as well as certain characteristics of the episodes, including trigger (i.e. type of odor), frequency, length, somatic symptoms, and the rate of associated flashbacks and catastrophic cognitions. Forty-five of the 100 patients had experienced an olfactory-triggered panic attack in the last month. Trauma associations and catastrophic cognitions (e.g. fears of a ‘wind attack,’ ‘weakness,’ and ‘weak heart’) were common during events of olfactory panic. Several case examples are presented. A multifactorial model of the generation of olfactory panic is adduced. The therapeutic implications of this model for the treatment of olfactory panic are discussed. PMID:15446720

Olfactory epithelium changes in germfree mice

PubMed Central

François, Adrien; Grebert, Denise; Rhimi, Moez; Mariadassou, Mahendra; Naudon, Laurent; Rabot, Sylvie; Meunier, Nicolas

2016-01-01

Intestinal epithelium development is dramatically impaired in germfree rodents, but the consequences of the absence of microbiota have been overlooked in other epithelia. In the present study, we present the first description of the bacterial communities associated with the olfactory epithelium and explored differences in olfactory epithelium characteristics between germfree and conventional, specific pathogen-free, mice. While the anatomy of the olfactory epithelium was not significantly different, we observed a thinner olfactory cilia layer along with a decreased cellular turn-over in germfree mice. Using electro-olfactogram, we recorded the responses of olfactory sensitive neuronal populations to various odorant stimulations. We observed a global increase in the amplitude of responses to odorants in germfree mice as well as altered responses kinetics. These changes were associated with a decreased transcription of most olfactory transduction actors and of olfactory xenobiotic metabolising enzymes. Overall, we present here the first evidence that the microbiota modulates the physiology of olfactory epithelium. As olfaction is a major sensory modality for most animal species, the microbiota may have an important impact on animal physiology and behaviour through olfaction alteration. PMID:27089944

Learning to smell: repeated exposure increases sensitivity to androstenone, a major component of boar taint.

PubMed

Mörlein, Daniel; Meier-Dinkel, Lisa; Moritz, Jasmin; Sharifi, Ahmad Reza; Knorr, Christoph

2013-08-01

This study aimed to assess whether repeated exposure affects subjects' ability to detect androstenone. Olfactory acuity of 77 female and 44 male subjects (age 37.5 ± 11.7 years) was assessed three times during six weeks. Replicate triangle tests using various dilutions of androstenone (0.5, 5.0, and 50.0 μg/g) on filter paper smell strips were applied. Subjects were either assigned to a test group (TRAIN) using androstenone for daily training, or to a control group (CONTR) using a placebo. For the low, the intermediate, and the high level of androstenone presented, detection rate increased from 14.1 to 30.6%, 40.5 to 62.8%, and 65.3 to 78.5% respectively within 6 weeks from the initial assessment. Results suggest that mere exposure during repeated olfactory testing increased subjects' ability to correctly discriminate androstenone. The olfactory improvement was, however, more pronounced in the TRAIN group. Androstenone detection appears to be associated with its individual appreciation. Copyright © 2013 Elsevier Ltd. All rights reserved.

Prenatal cocaine exposure impairs selective attention: evidence from serial reversal and extradimensional shift tasks.

PubMed

Garavan, H; Morgan, R E; Mactutus, C F; Levitsky, D A; Booze, R M; Strupp, B J

2000-08-01

This study assessed the effects of prenatal cocaine exposure on cognitive functioning, using an intravenous (IV) rodent model that closely mimics the pharmacokinetics seen in humans after smoking or IV injection and that avoids maternal stress and undernutrition. Cocaine-exposed males were significantly impaired on a 3-choice, but not 2-choice, olfactory serial reversal learning task. Both male and female cocaine-exposed rats were significantly impaired on extradimensional shift tasks that required shifting from olfactory to spatial cues; however, they showed no impairment when required to shift from spatial to olfactory cues. In-depth analyses of discrete learning phases implicated deficient selective attention as the basis of impairment in both tasks. These data provide clear evidence that prenatal cocaine exposure produces long-lasting cognitive dysfunction, but they also underscore the specificity of the impairment.

Olfactory Functioning in First-Episode Psychosis.

PubMed

Kamath, Vidyulata; Lasutschinkow, Patricia; Ishizuka, Koko; Sawa, Akira

2018-04-06

Though olfactory deficits are well-documented in schizophrenia, fewer studies have examined olfactory performance profiles across the psychosis spectrum. The current study examined odor identification, discrimination, and detection threshold performance in first-episode psychosis (FEP) patients diagnosed with schizophrenia, schizoaffective disorder, bipolar disorder with psychotic features, major depression with psychotic features, and other psychotic conditions. FEP patients (n = 97) and healthy adults (n = 98) completed birhinal assessments of odor identification, discrimination, and detection threshold sensitivity for lyral and citralva. Participants also completed measures of anticipatory pleasure, anhedonia, and empathy. Differences in olfactory performances were assessed between FEP patients and controls and within FEP subgroups. Sex-stratified post hoc analyses were employed for a complete analysis of sex differences. Relationships between self-report measures and olfactory scores were also examined. Individuals with psychosis had poorer scores across all olfactory measures when compared to the control group. Within the psychosis cohort, patients with schizophrenia-associated psychosis had poorer odor identification, discrimination, and citralva detection threshold scores relative to controls. In schizophrenia patients, greater olfactory disturbance was associated with increased negative symptomatology, greater self-reported anhedonia, and lower self-reported anticipatory pleasure. Patients with mood-associated psychosis performed comparable to controls though men and women in this cohort showed differential olfactory profiles. These findings indicate that olfactory deficits extend beyond measures of odor identification in FEP with greater deficits observed in schizophrenia-related subgroups of psychosis. Studies examining whether greater olfactory dysfunction confers greater risk for developing schizophrenia relative to other forms of psychosis are warranted.

Nitrogen dioxide pollution exposure is associated with olfactory dysfunction in older US adults

PubMed Central

Adams, Dara R.; Ajmani, Gaurav S.; Pun, Vivian C.; Wroblewski, Kristen E.; Kern, David W.; Schumm, L. Philip; McClintock, Martha K.; Suh, Helen H.; Pinto, Jayant M.

2017-01-01

Background Olfactory dysfunction has profound effects on quality of life, physical and social function, and mortality itself. Nitrogen dioxide (NO2) is a pervasive air pollutant that is associated with respiratory diseases. Given the olfactory nerve’s anatomic exposure to airborne pollutants, we investigated the relationship between NO2 exposure and olfactory dysfunction. Methods The ability to identify odors was evaluated using a validated test in respondents from the National Social Life, Health, and Aging Project (NSHAP), a representative probability sample of home-dwelling, older US adults ages 57–85. Exposure to NO2 pollution was assessed using measurements obtained from the US EPA AIRS ambient monitoring site closest to each respondent’s home. We tested the association between NO2 exposure and olfactory dysfunction using multivariate logistic regression. Results Among older adults in the US, 22.6% had impaired olfactory function, defined as ≤ 3 correct (out of 5) on the odor identification test. Median NO2 exposure during the 365 days prior to the interview date was 14.7 ppb (interquartile range [IQR] 10.8–19.7 ppb). An IQR increase in NO2 exposure was associated with increased odds of olfactory dysfunction (OR 1.35, 95% CI: 1.07–1.72), adjusting for age, gender, race/ethnicity, education, cognition, comorbidity, smoking, and season of the home interview (n=1,823). Conclusion We show for the first time that NO2 exposure is associated with olfactory dysfunction in older US adults. These results suggest an important role for NO2 exposure on olfactory dysfunction, and, potentially, nasal disease more broadly. PMID:27620703

Proteomics Reveals the Molecular Underpinnings of Stronger Learning and Memory in Eastern Compared to Western Bees*

PubMed Central

Meng, Lifeng; Huo, Xinmei; Feng, Mao; Fang, Yu; Han, Bin; Hu, Han; Wu, Fan; Li, Jianke

2018-01-01

The eastern (Apis cerana cerana, Acc) and western (Apis mellifera ligustica, Aml) honeybee are two major honeybee species. Surprisingly, little is known about the fundamental molecular neurobiology of brain suborgans of Acc and Aml. We characterized and compared the proteomes of mushroom bodies (MBs), antennal lobes (ALs) and optical lobes (OLs) in the brain of both species, and biologically validated the functions related to learning and memory. Acc and Aml have evolved similar proteome signatures in MBs and OLs to drive the domain-specific neural activities. In MBs of both species, commonly enriched and enhanced functional groups related to protein metabolism and Ca2+ transport relative to ALs and OLs, suggests that proteins and Ca2+ are vital for consolidating learning and memory via modulation of synaptic structure and signal transduction. Furthermore, in OLs of both species, the mainly enriched ribonucleoside metabolism suggests its vital role as second messenger in promoting phototransduction. Notably, in ALs of both species, distinct proteome settings have shaped to prime olfactory learning and memory. In ALs of Acc, this is supported by the enriched cytoskeleton organization to sustain olfactory signaling through modulation of plasticity in glomeruli and intracellular transport. In ALs of Aml, however, the enriched functional groups implicated in hydrogen ion transport are indicative of their importance in supporting olfactory processes by regulation of synaptic transmission. The biological confirmation of enhanced activities of protein metabolism and signal transduction in ALs and MBs of Acc relative to in Aml demonstrates that a stronger sense of olfactory learning and memory has evolved in Acc. The reported first in-depth proteome data of honeybee brain suborgans provide a novel insight into the molecular basis of neurobiology, and is potentially useful for further neurological studies in honeybees and other insects. PMID:29187519

Testicular receptor 2, Nr2c1, is associated with stem cells in the developing olfactory epithelium and other cranial sensory and skeletal structures.

PubMed

Baker, Jennifer L; Wood, Bernard; Karpinski, Beverly A; LaMantia, Anthony-S; Maynard, Thomas M

2016-01-01

Comparative genomic analysis of the nuclear receptor family suggests that the testicular receptor 2, Nr2c1, undergoes positive selection in the human-chimpanzee clade based upon a significant increase in nonsynonymous compared to synonymous substitutions. Previous in situ analyses of Nr2c1 lacked the temporal range and spatial resolution necessary to characterize cellular expression of this gene from early to mid gestation, when many nuclear receptors are key regulators of tissue specific stem or progenitor cells. Thus, we asked whether Nr2c1 protein is associated with stem cell populations in the mid-gestation mouse embryo. Nr2c1 is robustly expressed in the developing olfactory epithelium. Its expression in the olfactory epithelium shifts from multiple progenitor classes at early stages to primarily transit amplifying cells later in olfactory epithelium development. In the early developing central nervous system, Nr2c1 is limited to the anterior telencephalon/olfactory bulb anlagen, coincident with Nestin-positive neuroepithelial stem cells. Nr2c1 is also seen in additional cranial sensory specializations including cells surrounding the mystacial vibrissae, the retinal pigment epithelium and Scarpa's ganglion. Nr2c1 was also detected in a subset of mesenchymal cells in developing teeth and cranial bones. The timing and distribution of embryonic expression suggests that Nr2c1 is primarily associated with the early genesis of mammalian cranial sensory neurons and craniofacial skeletal structures. Thus, Nr2c1 may be a candidate for mediating parallel adaptive changes in cranial neural sensory specializations such as the olfactory epithelium, retina and mystacial vibrissae and in non-neural craniofacial features including teeth. Copyright © 2015 Elsevier B.V. All rights reserved.

Overlapping Risky Decision-Making and Olfactory Processing Ability in HIV-Infected Individuals.

PubMed

Jackson, Christopher; Rai, Narayan; McLean, Charlee K; Hipolito, Maria Mananita S; Hamilton, Flora Terrell; Kapetanovic, Suad; Nwulia, Evaristus A

2017-09-01

Given neuroimaging evidences of overlap in the circuitries for decision-making and olfactory processing, we examined the hypothesis that impairment in psychophysical tasks of olfaction would independently predict poor performances on Iowa Gambling Task (IGT), a laboratory task that closely mimics real-life decision-making, in a US cohort of HIV-infected (HIV+) individuals. IGT and psychophysical tasks of olfaction were administered to a Washington DC-based cohort of largely African American HIV+ subjects (N=100), and to a small number of demographically-matched non-HIV healthy controls (N=43) from a different study. Constructs of olfactory ability and decision-making were examined through confirmatory factor analysis (CFA). Structural equation models (SEMs) were used to evaluate the validity of the path relationship between these two constructs. The 100 HIV+ participants (56% female; 96% African Americans; median age = 48 years) had median CD4 count of 576 cells/μl and median HIV RNA viral load <48 copies per milliliter. Majority of HIV+ participants performed randomly throughout the course of IGT tasks, and failed to demonstrate a learning curve. Confirmatory factor analysis provided support for a unidimensional factor underlying poor performances on IGT. Nomological validity for correlations between olfactory ability and IGT performance was confirmed through SEM. Finally, factor scores of olfactory ability and IGT performance strongly predicted 6 months history of drug use, while olfaction additionally predicted hallucinogen use. This study suggests that combination of simple, office-based tasks of olfaction and decision-making may identify those HIV+ individuals who are more prone to risky decision-making. This finding may have significant clinical, public health value if joint impairments in olfaction and IGT task correlates with more decreased activity in brain regions relevant to decision-making.

Phenomenal and access consciousness in olfaction.

PubMed

Stevenson, Richard J

2009-12-01

Contemporary literature on consciousness, with some exceptions, rarely considers the olfactory system. In this article the characteristics of olfactory consciousness, viewed from the standpoint of the phenomenal (P)/access (A) distinction, are examined relative to the major senses. The review details several qualitative differences in both olfactory P consciousness (shifts in the felt location, universal synesthesia-like and affect-rich experiences, and misperceptions) and A consciousness (recovery from habituation, capacity for conscious processing, access to semantic and episodic memory, learning, attention, and in the serial-unitary nature of olfactory percepts). The basis for these differences is argued to arise from the functions that the olfactory system performs and from the unique neural architecture needed to instantiate them. These data suggest, at a minimum, that P and A consciousness are uniquely configured in olfaction and an argument can be made that the P and A distinction may not hold for this sensory system.

Role of neuropeptide Y (NPY) in the regulation of reproduction: study based on catfish model.

PubMed

Subhedar, Nishikant; Gaikwad, Archana; Biju, K C; Saha, Subhash

2005-04-01

Significance of NPY in the regulation of GnRH-LH axis was evaluated. Considerable NPY immunoreactivity was seen in the components like olfactory system, basal telencephalon, preoptic and tuberal areas, and the pituitary gland that serve as neuroanatomical substrates for processing reproductive information. Close anatomical association as well as colocalizations of NPY and GnRH were seen in the olfactory receptor neurons, olfactory nerve fibers and their terminals in the glomeruli, ganglion cells of nervus terminalis, medial olfactory tracts, fibers in the ventral telencephalon and pituitary. In the pituitary, NPY fibers seem to innervate the GnRH as well as LH cells. Intracranial administration of NPY resulted in significant increase in the GnRH immunoreactivity in all the components of the olfactory system. In the pituitary, NPY augmented the population of GnRH fibers and LH cells. HPLC analysis showed that salmon GnRH content in the olfactory organ, bulb, preoptic area+telencephalon and pituitary was also significantly increased following NPY treatment. NPY may play a role in positive regulation of GnRH throughout the neuraxis and also up-regulate the LH cells in the pituitary.

Olfactory modulation by dopamine in the context of aversive learning

PubMed Central

Riffell, Jeffrey A.; Martin, Joshua P.; Gage, Stephanie L.; Nighorn, Alan J.

2012-01-01

The need to detect and process sensory cues varies in different behavioral contexts. Plasticity in sensory coding can be achieved by the context-specific release of neuromodulators in restricted brain areas. The context of aversion triggers the release of dopamine in the insect brain, yet the effects of dopamine on sensory coding are unknown. In this study, we characterize the morphology of dopaminergic neurons that innervate each of the antennal lobes (ALs; the first synaptic neuropils of the olfactory system) of the moth Manduca sexta and demonstrate with electrophysiology that dopamine enhances odor-evoked responses of the majority of AL neurons while reducing the responses of a small minority. Because dopamine release in higher brain areas mediates aversive learning we developed a naturalistic, ecologically inspired aversive learning paradigm in which an innately appetitive host plant floral odor is paired with a mimic of the aversive nectar of herbivorized host plants. This pairing resulted in a decrease in feeding behavior that was blocked when dopamine receptor antagonists were injected directly into the ALs. These results suggest that a transient dopaminergic enhancement of sensory output from the AL contributes to the formation of aversive memories. We propose a model of olfactory modulation in which specific contexts trigger the release of different neuromodulators in the AL to increase olfactory output to downstream areas of processing. PMID:22552185

An odor identification approach based on event-related pupil dilation and gaze focus.

PubMed

Aguillon-Hernandez, Nadia; Naudin, Marine; Roché, Laëtitia; Bonnet-Brilhault, Frédérique; Belzung, Catherine; Martineau, Joëlle; Atanasova, Boriana

2015-06-01

Olfactory disorders constitute a potential marker of many diseases and are considered valuable clues to the diagnosis and evaluation of progression for many disorders. The most commonly used test for the evaluation of impairments of olfactory identification requires the active participation of the subject, who must select the correct name of the perceived odor from a list. An alternative method is required because speech may be impaired or not yet learned in many patients. As odor identification is known to be facilitated by searching for visual clues, we aimed to develop an objective, vision-based approach for the evaluation of odor identification. We used an eye tracking method to quantify pupillary and ocular responses during the simultaneous presentation of olfactory and visual stimuli, in 39 healthy participants aged from 19 to 77years. Odor presentation triggered an increase in pupil dilation and gaze focus on the picture corresponding to the odor presented. These results suggest that odorant stimuli increase recruitment of the sympathetic system (as demonstrated by the reactivity of the pupil) and draw attention to the visual clue. These results validate the objectivity of this method. Copyright © 2015 Elsevier B.V. All rights reserved.

Kinase activity in the olfactory bulb is required for odor memory consolidation.

PubMed

Tong, Michelle T; Kim, Tae-Young P; Cleland, Thomas A

2018-05-01

Long-term fear memory formation in the hippocampus and neocortex depends upon brain-derived neurotrophic factor (BDNF) signaling after acquisition. Incremental, appetitive odor discrimination learning is thought to depend substantially on the differentiation of adult-born neurons within the olfactory bulb (OB)-a process that is closely associated with BDNF signaling. We sought to elucidate the role of neurotrophin signaling within the OB on odor memory consolidation. Male mice were trained on odor-reward associative discriminations after bilateral infusion of the kinase inhibitor K252a, or vehicle control, into the OB. K252a is a partially selective inhibitor of tyrosine kinase (Trk) receptors, including the TrkB receptor for BDNF, though it also inhibits other plasticity-related kinases such as PKC and CaMKII/IV. K252a infusion into the OB did not impair odor acquisition or short-term (2 h) memory for the learned discriminations, but significantly impaired long-term (48 h) odor memory (LTM). This LTM deficit also was associated with reduced selectivity for the conditioned odorant in a reward-seeking digging task. Infusions of K252a immediately prior to testing did not impair LTM recall. These results indicate that kinase activation in the OB is required for the consolidation of odor memory of incrementally acquired information. © 2018 Tong et al.; Published by Cold Spring Harbor Laboratory Press.

The effects of partial sleep restriction and altered sleep timing on olfactory performance.

PubMed

McNeil, J; Forest, G; Hintze, L J; Brunet, J-F; Doucet, É

2017-12-01

Olfaction can increase the drive to eat and may partially explain the consistent increases in energy intake (EI) following sleep restriction. We investigated the effects of 50% sleep restriction with altered sleep timing on olfactory performance. We also evaluated whether changes (Δ) in olfactory performance were associated with Δ24 h EI. Twelve men and six women (age: 23±4 years; BMI: 23±3 kg/m 2 ) completed three randomized cross-over conditions: habitual sleep duration, 50% sleep restriction with advanced wake-time, and 50% sleep restriction with delayed bedtime. Sleep was measured in-laboratory (polysomnography). Olfactory performance ('sniffin sticks') and 24 h EI (food menu) were evaluated the next day. A trend for a significant condition*sex interaction was noted for threshold-discrimination-identification (TDI) scores (P=0.09); TDI scores were lowest in women and highest in men, following sleep restriction with advanced wake-time. Δolfactory performance were not associated with Δ24 h EI. The impact of sleep restriction on olfactory performance may differ between sexes. Changes in olfactory performance were not associated with changes in 24 h EI. Studies investigating prolonged effects of sleep loss on the relationship between olfactory performance with EI are needed.

Fluctuating olfactory sensitivity and distorted odor perception in allergic rhinitis.

PubMed

Apter, A J; Gent, J F; Frank, M E

1999-09-01

To characterize the relationship between allergic rhinitis, the severity and duration of nasal disease, olfactory function, and self-reported olfactory symptoms, including fluctuations or distortions in odor perception. Assessment of olfactory function and symptoms of 90 patients with allergic rhinitis. A clinic of a university teaching hospital and research facility. Sixty patients who presented to the Taste and Smell Clinic who had positive allergy test results and 30 patients who presented to the Allergy-Immunology Clinic. The Taste and Smell Clinic patients were grouped by nasal-sinus disease status (30 without chronic rhinosinusitis or nasal polyps, 14 with chronic rhinosinusitis but without polyps, and 16 with nasal polyps). Subjective olfactory symptom questionnaire and objective olfactory function tests. The Allergy-Immunology Clinic patients were diagnosed as being normosmic and the Taste and Smell Clinic patients as being hyposmic or anosmic with olfactory loss that increased significantly with nasal-sinus disease severity. Comparisons with normative data confirm that olfactory scores observed in all groups were significantly lower than expected because of the aging process alone. The self-reported duration of olfactory loss increased significantly with nasal-sinus disease severity. The Taste and Smell Clinic patients without chronic rhinosinusitis or nasal polyps reported the greatest incidence of olfactory distortions and olfactory loss associated with upper respiratory tract infections. There appears to be a continuum of duration and severity of olfactory loss in allergic rhinitis that parallels increasing severity of nasal-sinus disease. As a result of the increased frequency of respiratory infection associated with allergic rhinitis, these patients are at risk for damage to the olfactory epithelium.

Chemosensory interaction: acquired olfactory impairment is associated with decreased taste function.

PubMed

Landis, Basile N; Scheibe, Mandy; Weber, Cornelia; Berger, Robert; Brämerson, Annika; Bende, Mats; Nordin, Steven; Hummel, Thomas

2010-08-01

Olfaction, taste and trigeminal function are three distinct modalities. However, in daily life they are often activated concomitantly. In health and disease, it has been shown that in two of these senses, the trigeminal and olfactory senses, modification of one sense leads to changes in the other sense and vice versa. The objective of the study was to investigate whether and (if so) how, the third modality, taste, is influenced by olfactory impairment. We tested 210 subjects with normal (n = 107) or impaired (n = 103) olfactory function for their taste identification capacities. Validated tests were used for olfactory and gustatory testing (Sniffin' Sticks, Taste Strips). In an additional experiment, healthy volunteers underwent reversible olfactory cleft obstruction to investigate short-time changes of gustatory function after olfactory alteration. Mean gustatory identification (taste strip score) for the subjects with impaired olfaction was 19.4 +/- 0.6 points and 22.9 +/- 0.5 points for those with normal olfactory function (t = 4.6, p < 0.001). The frequencies of both, smell and taste impairments interacted significantly (Chi(2), F = 16.4, p < 0.001), and olfactory and gustatory function correlated (r (210) = 0.30, p < 0.001). Neither age nor olfactory impairment cause effects interfered with this olfactory-gustatory interaction. In contrast, after short-lasting induced olfactory decrease, gustatory function remained unchanged. The present study suggests that longstanding impaired olfactory function is associated with decreased gustatory function. These findings seem to extend previously described mutual chemosensory interactions also to smell and taste. It further raises the question whether chemical senses in general decrease mutually after acquired damage.

Density of mushroom body synaptic complexes limits intraspecies brain miniaturization in highly polymorphic leaf-cutting ant workers

PubMed Central

Groh, Claudia; Kelber, Christina; Grübel, Kornelia; Rössler, Wolfgang

2014-01-01

Hymenoptera possess voluminous mushroom bodies (MBs), brain centres associated with sensory integration, learning and memory. The mushroom body input region (calyx) is organized in distinct synaptic complexes (microglomeruli, MG) that can be quantified to analyse body size-related phenotypic plasticity of synaptic microcircuits in these small brains. Leaf-cutting ant workers (Atta vollenweideri) exhibit an enormous size polymorphism, which makes them outstanding to investigate neuronal adaptations underlying division of labour and brain miniaturization. We particularly asked how size-related division of labour in polymorphic workers is reflected in volume and total numbers of MG in olfactory calyx subregions. Whole brains of mini, media and large workers were immunolabelled with anti-synapsin antibodies, and mushroom body volumes as well as densities and absolute numbers of MG were determined by confocal imaging and three-dimensional analyses. The total brain volume and absolute volumes of olfactory mushroom body subdivisions were positively correlated with head widths, but mini workers had significantly larger MB to total brain ratios. Interestingly, the density of olfactory MG was remarkably independent from worker size. Consequently, absolute numbers of olfactory MG still were approximately three times higher in large compared with mini workers. The results show that the maximum packing density of synaptic microcircuits may represent a species-specific limit to brain miniaturization. PMID:24807257

Sublethal Dosage of Imidacloprid Reduces the Microglomerular Density of Honey Bee Mushroom Bodies

PubMed Central

Peng, Yi-Chan; Yang, En-Cheng

2016-01-01

The dramatic loss of honey bees is a major concern worldwide. Previous studies have indicated that neonicotinoid insecticides cause behavioural abnormalities and have proven that exposure to sublethal doses of imidacloprid during the larval stage decreases the olfactory learning ability of adults. The present study shows the effect of sublethal doses of imidacloprid on the neural development of the honey bee brain by immunolabelling synaptic units in the calyces of mushroom bodies. We found that the density of the synaptic units in the region of the calyces, which are responsible for olfactory and visual functions, decreased after being exposed to a sublethal dose of imidacloprid. This not only links a decrease in olfactory learning ability to abnormal neural connectivity but also provides evidence that imidacloprid damages the development of the nervous system in regions responsible for both olfaction and vision during the larval stage of the honey bee. PMID:26757950

Protectiveness of water quality criteria for copper in western United States waters relative to predicted olfactory responses in juvenile Pacific salmon.

PubMed

DeForest, David K; Gensemer, Robert W; Van Genderen, Eric J; Gorsuch, Joseph W

2011-07-01

Copper (Cu) can impair olfaction in juvenile Pacific salmon (as well as other fishes), thus potentially inhibiting the ability of juveniles to avoid predators or to find food. Because Cu is commonly elevated in stormwater runoff in urban environments, storm events may result in elevated Cu concentrations in salmon-bearing streams. Accordingly, there is concern that existing Cu criteria, which were not derived using data for olfactory-related endpoints, may not be adequately protective of juvenile salmon. However, a modification of the US Environmental Protection Agency (USEPA) biotic ligand model (BLM) for deriving site-specific Cu criteria was recently proposed, which accounted for the sensitivity of olfactory endpoints. The modification was based on olfactory inhibition in juvenile coho salmon (Oncorhynchus kisutch) exposed to Cu in various combinations of pH, hardness, alkalinity, and dissolved organic carbon (DOC) concentrations. We used that olfactory-based BLM to derive 20% inhibition concentrations (IC20) values for Cu for 133 stream locations in the western United States. The olfactory BLM-based IC20 values were compared to the existing hardness-based Cu criteria and the USEPA's BLM-based Cu criteria for these representative natural waters of the western United States. Of the 133 sampling locations, mean hardness-dependent acute and chronic Cu criteria were below the mean olfactory-based BLM IC20 value in 122 (92%) and 129 (97%) of the waters, respectively (i.e., <20% olfactory impairment would have been predicted at the mean hardness-based Cu criteria concentrations). Waters characterized by a combination of high hardness and very low DOC were most likely to have hardness-based Cu criteria that were higher than the olfactory-based BLM IC20 values, because DOC strongly influences Cu bioavailability in the BLM. In all waters, the USEPA's current BLM-based criteria were below the mean olfactory-based BLM IC20 values, indicating that the USEPA's BLM-based criteria are protective of olfactory impairment in juvenile salmon. Copyright © 2011 SETAC.

Effects of Ambient Air Pollution Exposure on Olfaction: A Review.

PubMed

Ajmani, Gaurav S; Suh, Helen H; Pinto, Jayant M

2016-11-01

Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recent studies have considered effects from exposure to ambient air pollutants. To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss. We identified and reviewed relevant articles from 1950 to 2015 using PubMed and Web of Science and focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function. We identified and reviewed 17 articles, with 1 additional article added from a bibliography search, for a total of 18 human studies. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology or inducing local inflammation and cellular stress responses. Ambient air pollution may impact human olfactory function. Additional studies are needed to examine air pollution-related olfactory impacts on the general population using measured pollution exposures and to link pollution exposure with olfactory dysfunction and related pathology. Citation: Ajmani GS, Suh HH, Pinto JM. 2016. Effects of ambient air pollution exposure on olfaction: a review. Environ Health Perspect 124:1683-1693; http://dx.doi.org/10.1289/EHP136.

Gustatory Learning and Processing in the Drosophila Mushroom Bodies

PubMed Central

Kirkhart, Colleen

2015-01-01

The Drosophila mushroom bodies are critical association areas whose role in olfactory associative learning has been well characterized. Recent behavioral studies using a taste association paradigm revealed that gustatory conditioning also requires the mushroom bodies (Masek and Scott, 2010; Keene and Masek, 2012). Here, we examine the representations of tastes and the neural sites for taste associations in the mushroom bodies. Using molecular genetic approaches to target different neuronal populations, we find that the gamma lobes of the mushroom bodies and a subset of dopaminergic input neurons are required for taste associative learning. Monitoring responses to taste compounds in the mushroom body calyx with calcium imaging reveals sparse, taste-specific and organ-specific activation in the Kenyon cell dendrites of the main calyx and the dorsal accessory calyx. Our work provides insight into gustatory representations in the mushroom bodies, revealing the essential role of gustatory inputs not only as rewards and punishments but also as adaptive cues. PMID:25878268

Olfactory priming reinstates extinguished chocolate-induced conditioned place preference.

PubMed

La Mela, Immacolata; Latagliata, Emanuele Claudio; Patrono, Enrico; Puglisi-Allegra, Stefano; Ventura, Rossella

2010-02-01

A major problem in the dietary treatment of disorders associated with excessive eating, such as obesity, is the high rate of relapse into maladaptive eating habits after withdrawal from consumption of palatable, energy-dense food. As olfaction has a major role in appetite and eating behavior, in this study we used a reinstatement model based on conditioned place preference to investigate the ability of olfactory priming to reinstate extinguished chocolate-induced conditioned place preference in sated mice. We found that olfactory priming, which was ineffective in inducing conditioned place preference in the control group, reactivated place preference following the extinction procedure in the experimental group. These results extend previous reports of the reinstatement of food seeking induced by pellet priming and, for the first time, show the possibility of using olfactory priming in an animal model of relapse. In light of the major role of olfactory inputs in appetite and of cues in relapse, the present results indicate that smell is an important factor to consider in the treatment of eating disorders. 2009 Elsevier Ltd. All rights reserved.

Mice with a "monoclonal nose": perturbations in an olfactory map impair odor discrimination.

PubMed

Fleischmann, Alexander; Shykind, Benjamin M; Sosulski, Dara L; Franks, Kevin M; Glinka, Meredith E; Mei, Dan Feng; Sun, Yonghua; Kirkland, Jennifer; Mendelsohn, Monica; Albers, Mark W; Axel, Richard

2008-12-26

We have altered the neural representation of odors in the brain by generating a mouse with a "monoclonal nose" in which greater than 95% of the sensory neurons express a single odorant receptor, M71. As a consequence, the frequency of sensory neurons expressing endogenous receptor genes is reduced 20-fold. We observe that these mice can smell, but odor discrimination and performance in associative olfactory learning tasks are impaired. However, these mice cannot detect the M71 ligand acetophenone despite the observation that virtually all sensory neurons and glomeruli are activated by this odor. The M71 transgenic mice readily detect other odors in the presence of acetophenone. These observations have implications for how receptor activation in the periphery is represented in the brain and how these representations encode odors.

Noradrenergic Control of Odor Recognition in a Nonassociative Olfactory Learning Task in the Mouse

ERIC Educational Resources Information Center

Veyrac, Alexandra; Nguyen, Veronique; Marien, Marc; Didier, Anne; Jourdan, Francois

2007-01-01

The present study examined the influence of pharmacological modulations of the locus coeruleus noradrenergic system on odor recognition in the mouse. Mice exposed to a nonrewarded olfactory stimulation (training) were able to memorize this odor and to discriminate it from a new odor in a recall test performed 15 min later. At longer delays (30 or…

Bilateral Olfactory Mucosa Damage Induces the Disappearance of Olfactory Glomerulus and Reduces the Expression of Extrasynaptic α5GABAARs in the Hippocampus in Early Postnatal Sprague Dawley Rats.

PubMed

Zheng, Xiaomin; Liang, Liang; Hei, Changchun; Yang, Wenjuan; Zhang, Tingyuan; Wu, Kai; Qin, Yi; Chang, Qing

2018-04-17

Chloroform-induced olfactory mucosal degeneration has been reported in adult rats following gavage. We used fixed-point chloroform infusions on different postnatal days (PNDs) to investigate the effects of early olfactory bilateral deprivation on the main olfactory bulbs in Sprague Dawley rats. The experimental groups included rats infused with chloroform (5 μl) or saline (sham, 5 μl) on PNDs 3 and 8, and rats not receiving infusions (control) (n = 6 in all groups). Rats receiving chloroform on PND 3 showed significant hypoevolutism when compared to those in other groups (P < 0.05). There was a complete disappearance and a significant reduction in the size of olfactory glomeruli in the PND 3 and 8 groups, respectively, when compared to the respective sham groups. Rats receiving chloroform on PND 3 had significant memory impairment (P < 0.01) and increased levels of learned helplessness (P < 0.05), as measured using the Morris water maze and tail suspension tests, respectively. GABA A receptor alpha5 subunit (α5GABA A R) expression in hippocampal neurons was significantly lower in rats receiving chloroform on PND 3 than in rats in other groups (P < 0.01), as measured using immunohistochemistry and polymerase chain reaction. There was thus a critical period for the preservation of regenerative ability in olfactory receptor neurons, during which damage and olfactory deprivation led to altered rhinencephalon structure and disappearance of olfactory glomeruli, which induced hypoevolutism. Olfactory deprivation after the critical period had no significant effect on olfactory receptor neuron regeneration, leading to reduced developmental and behavioral effects in Sprague Dawley rats.

Learning in the Absence of Experience-Dependent Regulation of NMDAR Composition

ERIC Educational Resources Information Center

Lebel, David; Sidhu, Nishchal; Barkai, Edi; Quinlan, Elizabeth M.

2006-01-01

Olfactory discrimination (OD) learning consists of two phases: an initial N-methyl-d-aspartate (NMDA) receptor--sensitive rule-learning phase, followed by an NMDA receptor (NMDAR)--insensitive pair-learning phase. The rule-learning phase is accompanied by changes in the composition and function of NMDARs at synapses in the piriform cortex,…

Cognitive Impairment and Structural Abnormalities in Late Life Depression with Olfactory Identification Impairment: an Alzheimer's Disease-Like Pattern.

PubMed

Chen, Ben; Zhong, Xiaomei; Mai, Naikeng; Peng, Qi; Wu, Zhangying; Ouyang, Cong; Zhang, Weiru; Liang, Wanyuan; Wu, Yujie; Liu, Sha; Chen, Lijian; Ning, Yuping

2018-03-15

Late-life depression patients are at a high risk of developing Alzheimer's disease, and diminished olfactory identification is an indicator in early screening for Alzheimer's disease in the elderly. However, whether diminished olfactory identification is associated with risk of developing Alzheimer's disease in late-life depression patients remains unclear. One hundred and twenty-five late-life depression patients, 50 Alzheimer's disease patients, and 60 normal controls were continuously recruited. The participants underwent a clinical evaluation, olfactory test, neuropsychological assessment, and neuroimaging assessment. The olfactory identification impairment in late-life depression patients was milder than that in Alzheimer's disease patients. Diminished olfactory identification was significantly correlated with worse cognitive performance (global function, memory language, executive function, and attention) and reduced grey matter volume (olfactory bulb and hippocampus) in the late-life depression patients. According to a multiple linear regression analysis, olfactory identification was significantly associated with the memory scores in late-life depression group (B=1.623, P<.001). The late-life depression with olfactory identification impairment group had worse cognitive performance (global, memory, language, and executive function) and more structural abnormalities in Alzheimer's disease-related regions than the late-life depression without olfactory identification impairment group, and global cognitive function and logical memory in the late-life depression without olfactory identification impairment group was intact. Reduced volume observed in many areas (hippocampus, precuneus, etc.) in the Alzheimer's disease group was also observed in late-life depression with olfactory identification impairment group but not in the late-life depression without olfactory identification impairment group. The patterns of cognitive impairment and structural abnormalities in late-life depression with olfactory identification impairment patients were similar to those in Alzheimer's disease; olfactory identification may help identify late-life depression patients who are at a high risk of developing Alzheimer's disease.

Ontogenetic changes in responses to settlement cues by Anemonefish

NASA Astrophysics Data System (ADS)

Dixson, D. L.; Munday, P. L.; Pratchett, M.; Jones, G. P.

2011-12-01

Population connectivity for most marine species is dictated by dispersal during the pelagic larval stage. Although reef fish larvae are known to display behavioral adaptations that influence settlement site selection, little is known about the development of behavioral preferences throughout the larval phase. Whether larvae are attracted to the same sensory cues throughout their larval phase, or exhibit distinct ontogenetic shifts in sensory preference is unknown. Here, we demonstrate an ontogenetic shift in olfactory cue preferences for two species of anemonefish, a process that could aid in understanding both patterns of dispersal and settlement. Aquarium-bred naïve Amphiprion percula and A. melanopus larvae were tested for olfactory preference of relevant reef-associated chemical cues throughout the 11-day pelagic larval stage. Age posthatching had a significant effect on the preference for olfactory cues from host anemones and live corals for both species. Preferences of olfactory cues from tropical plants of A. percula, increased by approximately ninefold between hatching and settlement, with A. percula larvae showing a fivefold increase in preference for the olfactory cue produced by the grass species. Larval age had no effect on the olfactory preference for untreated seawater over the swamp-based tree Melaleuca nervosa, which was always avoided compared with blank seawater. These results indicate that reef fish larvae are capable of utilizing olfactory cues early in the larval stage and may be predisposed to disperse away from reefs, with innate olfactory preferences drawing newly hatched larvae into the pelagic environment. Toward the end of the larval phase, larvae become attracted to the olfactory cues of appropriate habitats, which may assist them in identification of and navigation toward suitable settlement sites.

Olfaction: New Understandings, Diagnostic Applications.

PubMed

Ruggiero, Gabrielle F; Wick, Jeannette Y

2016-11-01

Estimates indicate that 14 million Americans have olfactory dysfunction. As with other senses, such as sight and hearing, olfaction frequently declines with age. Impaired olfaction can be a warning sign of Parkinson's disease, sometimes occurring before motor symptoms develop. It's also an initial symptom of Alzheimer's dementia (AD); the amyloid plaques and tangles characterizing AD invade the olfactory bulb and hippocampus early in its course, hampering odor identification. Olfactory dysfunction is associated with some serious problems, including inability to smell warning odors (fire, gas) and impaired ability to taste food. Standardized, validated methods are available to measure several different dimensions of olfactory function, including odor identification, discrimination, and threshold levels. Researchers are currently studying the unique olfactory deficits associated with different conditions in hopes of identifying new, noninvasive tools for early diagnosis and treatment. Drugs may cause or contribute to olfactory dysfunction, but it can be difficult to pinpoint offending medications.

Ethmoid Histopathology Does Not Predict Olfactory Outcomes after Endoscopic Sinus Surgery

PubMed Central

Soler, Zachary M.; Sauer, David A.; Mace, Jess C.; Smith, Timothy L.

2010-01-01

BACKGROUND Histologic inflammation correlates with the degree of baseline olfactory dysfunction in patients with chronic rhinosinusitis (CRS), however factors associated with improvement in olfactory status after endoscopic sinus surgery (ESS) remain elusive. OBJECTIVE Our purpose was to compare histopathologic findings in CRS patients with olfactory loss and evaluate whether inflammatory markers can predict long-term olfactory improvement after ESS. METHODS Adult (≥18 years) patients with CRS were prospectively enrolled after electing ESS due to failed medical management. Mucosal tissue specimens were collected at the time of surgery and underwent pathlogic review in a blinded fashion. Subjects completed the 40-item Smell Identification Test (SIT) preoperatively and at least 6 months postoperatively. Multivariate logistic regression was used to identify histologic factors associated with postoperative improvement in SIT score. RESULTS The final cohort was comprised of 101 patients with a mean follow-up of 16.7 ± 6.0 months. Mean mucosal eosinophil count was higher in patients with hyposmia and anosmia (p<0.001). Patients with preoperative anosmia were more likely to have greater severity of BM thickening compared to subjects with hyposmia or normosmia (p=0.021). In patients with olfactory dysfunction, 54.7% reported olfactory improvement of at least 4 points on postoperative SIT scores. After controlling for nasal polyposis, histologic variables were not associated with postoperative improvement in olfaction. CONCLUSIONS Patients with severe olfactory dysfunction were more likely to have mucosal eosinophilia and basement membrane thickening on ethmoid histopathologic examination compared to normosmics. The presence of specific histologic inflammatory findings did not however predict olfactory improvement after surgery. PMID:20819467

Neural Correlates of Odor Learning in the Presynaptic Microglomerular Circuitry in the Honeybee Mushroom Body Calyx.

PubMed

Haenicke, Joachim; Yamagata, Nobuhiro; Zwaka, Hanna; Nawrot, Martin; Menzel, Randolf

2018-01-01

The mushroom body (MB) in insects is known as a major center for associative learning and memory, although exact locations for the correlating memory traces remain to be elucidated. Here, we asked whether presynaptic boutons of olfactory projection neurons (PNs) in the main input site of the MB undergo neuronal plasticity during classical odor-reward conditioning and correlate with the conditioned behavior. We simultaneously measured Ca 2+ responses in the boutons and conditioned behavioral responses to learned odors in honeybees. We found that the absolute amount of the neural change for the rewarded but not for the unrewarded odor was correlated with the behavioral learning rate across individuals. The temporal profile of the induced changes matched with odor response dynamics of the MB-associated inhibitory neurons, suggestive of activity modulation of boutons by this neural class. We hypothesize the circuit-specific neural plasticity relates to the learned value of the stimulus and underlies the conditioned behavior of the bees.

Associative learning changes cross-modal representations in the gustatory cortex

PubMed Central

Vincis, Roberto; Fontanini, Alfredo

2016-01-01

A growing body of literature has demonstrated that primary sensory cortices are not exclusively unimodal, but can respond to stimuli of different sensory modalities. However, several questions concerning the neural representation of cross-modal stimuli remain open. Indeed, it is poorly understood if cross-modal stimuli evoke unique or overlapping representations in a primary sensory cortex and whether learning can modulate these representations. Here we recorded single unit responses to auditory, visual, somatosensory, and olfactory stimuli in the gustatory cortex (GC) of alert rats before and after associative learning. We found that, in untrained rats, the majority of GC neurons were modulated by a single modality. Upon learning, both prevalence of cross-modal responsive neurons and their breadth of tuning increased, leading to a greater overlap of representations. Altogether, our results show that the gustatory cortex represents cross-modal stimuli according to their sensory identity, and that learning changes the overlap of cross-modal representations. DOI: http://dx.doi.org/10.7554/eLife.16420.001 PMID:27572258

[Gender-dependent effects of histone deacetylase inhibitor sodium valproate on early olfactory learning in 129Sv mice].

PubMed

Burenkova, O V; Aleksandrova, E A; Zaraĭskaia, I Iu

2013-02-01

In the brain, histone acetylation underlies both learning and the maintenance of long-term sustained effects of early experience which is further epigenetically inherited. However, the role of acetylation in learning previously has only been studied in adult animals: high level of learning could be dependent on high levels of histone H3 acetylation in the brain. The role of acetylation in the mechanisms of early learning has not been studied. In the present work, we were interested whether histone deacetylase inhibitor sodium valproate which increases the level of histone H3 acetylation will affect early olfactory discrimination learning in 8-day-old pups of 129Sv mice that are characterized by low efficiency of learning with imitation of maternal grooming. Multiple valproate injections from 3rd to 6th postnatal day had a gender-dependent effect: learning was selectively improved in male but not in female pups. In the female pups, learning improvement was observed after multiple injections of saline. Possible epigenetic mechanisms underlying these sex differences are discussed.

An Olfactory Indicator for Acid-Base Titrations.

ERIC Educational Resources Information Center

Flair, Mark N.; Setzer, William N.

1990-01-01

The use of an olfactory acid-base indicator in titrations for visually impaired students is discussed. Potential olfactory indicators include eugenol, thymol, vanillin, and thiophenol. Titrations performed with each indicator with eugenol proved to be successful. (KR)

Molecular mechanisms underlying formation of long-term reward memories and extinction memories in the honeybee (Apis mellifera)

PubMed Central

2014-01-01

The honeybee (Apis mellifera) has long served as an invertebrate model organism for reward learning and memory research. Its capacity for learning and memory formation is rooted in the ecological need to efficiently collect nectar and pollen during summer to ensure survival of the hive during winter. Foraging bees learn to associate a flower's characteristic features with a reward in a way that resembles olfactory appetitive classical conditioning, a learning paradigm that is used to study mechanisms underlying learning and memory formation in the honeybee. Due to a plethora of studies on appetitive classical conditioning and phenomena related to it, the honeybee is one of the best characterized invertebrate model organisms from a learning psychological point of view. Moreover, classical conditioning and associated behavioral phenomena are surprisingly similar in honeybees and vertebrates, suggesting a convergence of underlying neuronal processes, including the molecular mechanisms that contribute to them. Here I review current thinking on the molecular mechanisms underlying long-term memory (LTM) formation in honeybees following classical conditioning and extinction, demonstrating that an in-depth analysis of the molecular mechanisms of classical conditioning in honeybees might add to our understanding of associative learning in honeybees and vertebrates. PMID:25225299

Exposure to multiple cholinergic pesticides impairs olfactory learning and memory in honeybees.

PubMed

Williamson, Sally M; Wright, Geraldine A

2013-05-15

Pesticides are important agricultural tools often used in combination to avoid resistance in target pest species, but there is growing concern that their widespread use contributes to the decline of pollinator populations. Pollinators perform sophisticated behaviours while foraging that require them to learn and remember floral traits associated with food, but we know relatively little about the way that combined exposure to multiple pesticides affects neural function and behaviour. The experiments reported here show that prolonged exposure to field-realistic concentrations of the neonicotinoid imidacloprid and the organophosphate acetylcholinesterase inhibitor coumaphos and their combination impairs olfactory learning and memory formation in the honeybee. Using a method for classical conditioning of proboscis extension, honeybees were trained in either a massed or spaced conditioning protocol to examine how these pesticides affected performance during learning and short- and long-term memory tasks. We found that bees exposed to imidacloprid, coumaphos, or a combination of these compounds, were less likely to express conditioned proboscis extension towards an odor associated with reward. Bees exposed to imidacloprid were less likely to form a long-term memory, whereas bees exposed to coumaphos were only less likely to respond during the short-term memory test after massed conditioning. Imidacloprid, coumaphos and a combination of the two compounds impaired the bees' ability to differentiate the conditioned odour from a novel odour during the memory test. Our results demonstrate that exposure to sublethal doses of combined cholinergic pesticides significantly impairs important behaviours involved in foraging, implying that pollinator population decline could be the result of a failure of neural function of bees exposed to pesticides in agricultural landscapes.

Exposure to multiple cholinergic pesticides impairs olfactory learning and memory in honeybees

PubMed Central

Williamson, Sally M.; Wright, Geraldine A.

2013-01-01

SUMMARY Pesticides are important agricultural tools often used in combination to avoid resistance in target pest species, but there is growing concern that their widespread use contributes to the decline of pollinator populations. Pollinators perform sophisticated behaviours while foraging that require them to learn and remember floral traits associated with food, but we know relatively little about the way that combined exposure to multiple pesticides affects neural function and behaviour. The experiments reported here show that prolonged exposure to field-realistic concentrations of the neonicotinoid imidacloprid and the organophosphate acetylcholinesterase inhibitor coumaphos and their combination impairs olfactory learning and memory formation in the honeybee. Using a method for classical conditioning of proboscis extension, honeybees were trained in either a massed or spaced conditioning protocol to examine how these pesticides affected performance during learning and short- and long-term memory tasks. We found that bees exposed to imidacloprid, coumaphos, or a combination of these compounds, were less likely to express conditioned proboscis extension towards an odor associated with reward. Bees exposed to imidacloprid were less likely to form a long-term memory, whereas bees exposed to coumaphos were only less likely to respond during the short-term memory test after massed conditioning. Imidacloprid, coumaphos and a combination of the two compounds impaired the bees' ability to differentiate the conditioned odour from a novel odour during the memory test. Our results demonstrate that exposure to sublethal doses of combined cholinergic pesticides significantly impairs important behaviours involved in foraging, implying that pollinator population decline could be the result of a failure of neural function of bees exposed to pesticides in agricultural landscapes. PMID:23393272

A coupled-oscillator model of olfactory bulb gamma oscillations

PubMed Central

2017-01-01

The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING), best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity. PMID:29140973

Cognitive impairment and olfactory panic from occupational exposure to VOCs.

PubMed

Reinhartz, Abe

2006-10-01

A Canadian government clerical worker in her early thirties developed frontal lobe dysfunction from inhalation of volatile organic compounds off-gassed during an office renovation. Pulmonary function, bronchial provocation, allergy testing, and a brain (SPECT) scan were performed. SPECT scanning showed frontotemporal hypoperfusion and neuropsychologic testing revealed deficits in verbal learning and poor organizational memory. A significant component of this worker's impairment was the development of "olfactory panic," a debilitating aversion to odor accompanied by symptoms of panic. The Ontario Workplace Safety and Insurance Appeals Tribunal granted entitlement for her cognitive difficulties and olfactory panic as a result of her toxic exposure.

A challenge to chaotic itinerancy from brain dynamics

NASA Astrophysics Data System (ADS)

Kay, Leslie M.

2003-09-01

Brain hermeneutics and chaotic itinerancy proposed by Tsuda are attractive characterizations of perceptual dynamics in the mammalian olfactory system. This theory proposes that perception occurs at the interface between itinerant neural representation and interaction with the environment. Quantifiable application of these dynamics has been hampered by the lack of definable history and action processes which characterize the changes induced by behavioral state, attention, and learning. Local field potentials measured from several brain areas were used to characterize dynamic activity patterns for their use as representations of history and action processes. The signals were recorded from olfactory areas (olfactory bulb, OB, and pyriform cortex) and hippocampal areas (entorhinal cortex and dentate gyrus, DG) in the brains of rats. During odor-guided behavior the system shows dynamics at three temporal scales. Short time-scale changes are system-wide and can occur in the space of a single sniff. They are predictable, associated with learned shifts in behavioral state and occur periodically on the scale of the intertrial interval. These changes occupy the theta (2-12 Hz), beta (15-30 Hz), and gamma (40-100 Hz) frequency bands within and between all areas. Medium time-scale changes occur relatively unpredictably, manifesting in these data as alterations in connection strength between the OB and DG. These changes are strongly correlated with performance in associated trial blocks (5-10 min) and may be due to fluctuations in attention, mood, or amount of reward received. Long time-scale changes are likely related to learning or decline due to aging or disease. These may be modeled as slow monotonic processes that occur within or across days or even weeks or years. The folding of different time scales is proposed as a mechanism for chaotic itinerancy, represented by dynamic processes instead of static connection strengths. Thus, the individual maintains continuity of experience within the stability of fast periodic and slow monotonic processes, while medium scale events alter experience and performance dramatically but temporarily. These processes together with as yet to be determined action effects from motor system feedback are proposed as an instantiation of brain hermeneutics and chaotic itinerancy.

Relationships between pathologic subjective halitosis, olfactory reference syndrome, and social anxiety in young Japanese women.

PubMed

Tsuruta, Miho; Takahashi, Toru; Tokunaga, Miki; Iwasaki, Masanori; Kataoka, Shota; Kakuta, Satoko; Soh, Inho; Awano, Shuji; Hirata, Hiromi; Kagawa, Masaharu; Ansai, Toshihiro

2017-03-14

Pathologic subjective halitosis is known as a halitosis complaint without objective confirmation of halitosis by others or by halitometer measurements; it has been reported to be associated with social anxiety disorder. Olfactory reference syndrome is a preoccupation with the false belief that one emits a foul and offensive body odor. Generally, patients with olfactory reference syndrome are concerned with multiple body parts. However, the mouth is known to be the most common source of body odor for those with olfactory reference syndrome, which could imply that the two conditions share similar features. Therefore, we investigated potential causal relationships among pathologic subjective halitosis, olfactory reference syndrome, social anxiety, and preoccupations with body part odors. A total of 1360 female students (mean age 19.6 ± 1.1 years) answered a self-administered questionnaire regarding pathologic subjective halitosis, olfactory reference syndrome, social anxiety, and preoccupation with odors of body parts such as mouth, body, armpits, and feet. The scale for pathologic subjective halitosis followed that developed by Tsunoda et al.; participants were divided into three groups based on their scores (i.e., levels of pathologic subjective halitosis). A Bayesian network was used to analyze causal relationships between pathologic subjective halitosis, olfactory reference syndrome, social anxiety, and preoccupations with body part odors. We found statistically significant differences in the results for olfactory reference syndrome and social anxiety among the various levels of pathologic subjective halitosis (P < 0.001). Residual analyses indicated that students with severe levels of pathologic subjective halitosis showed greater preoccupations with mouth and body odors (P < 0.05). Bayesian network analysis showed that social anxiety directly influenced pathologic subjective halitosis and olfactory reference syndrome. Preoccupations with mouth and body odors also influenced pathologic subjective halitosis. Social anxiety may be a causal factor of pathologic subjective halitosis and olfactory reference syndrome.

Variables associated with olfactory disorders in adults: A U.S. population-based analysis.

PubMed

Noel, Julia; Habib, Al-Rahim R; Thamboo, Andrew; Patel, Zara M

2017-03-01

Olfactory dysfunction is known to have significant social, psychological, and safety implications. Despite increasingly recognized prevalence, potential risk factors for olfactory loss have been arbitrarily documented and knowledge is limited in scale. The aim of this study is to identify potential demographic and exposure variables correlating with olfactory dysfunction. Cross-sectional analysis of the 2011-2012 and 2013-2014 editions of the National Health Examination and Nutrition Survey was performed. The utilized survey reports from a nationally representative sample of about 5000 persons each year located in counties across the United States. There is an interview and physical examination component which includes demographic, socioeconomic, dietary, and health-related questions as well as medical, dental, physiologic measurements, and laboratory tests. 3594 adult respondents from 2011 to 2012 and 3708 respondents from 2013 to 2014 were identified from the above population-based database. The frequency of self-reported disorders as well as performance on odor identification testing was determined in relation to demographic factors, occupational or environmental exposures, and urinary levels of environmental and industrial compounds. In both subjective and objective analysis, smell disorders were significantly more common with increasing age. While the non-Hispanic Black and non-Hispanic Asian populations were less likely to report subjective olfactory loss, they, along with Hispanics, performed more poorly on odor identification than Caucasians. Those with limited education had a decreased prevalence of hyposmia. Women outperformed men on smell testing. Those reporting exposure to vapors were more likely to experience olfactory dysfunction, and urinary levels of manganese, 2-Thioxothiazolidine-4-carboxylic acid, and 2-Aminothiazoline-4-carboxylic acid were lower among respondents with subjective smell disturbance. In odor detection, elevated serum levels of lead and urinary levels of 2,4 dichlorophenol were associated with anosmia and hyposmia, respectively. This study provides current, population-based data identifying demographic and exposure elements related to smell disturbances in U.S. adults. Age, race, gender, education, exposure to vapors, urinary levels of manganese, 2-Thioxothiazolidine-4-carboxylic acid, 2-Aminothiazoline-4-carboxylic acid, 2,4 dichlorophenol, and serum lead levels were all implicated in smell disturbance. Care should be taken in interpretation due to lack of consistency between subjective and objective measures of olfaction as well as limitations related to population-based data. Prospective trials are indicated to further elucidate these relationships.

Effects of Ambient Air Pollution Exposure on Olfaction: A Review

PubMed Central

Ajmani, Gaurav S.; Suh, Helen H.; Pinto, Jayant M.

2016-01-01

Background: Olfactory dysfunction affects millions of people worldwide. This sensory impairment is associated with neurodegenerative disease and significantly decreased quality of life. Exposure to airborne pollutants has been implicated in olfactory decline, likely due to the anatomic susceptibility of the olfactory nerve to the environment. Historically, studies have focused on occupational exposures, but more recent studies have considered effects from exposure to ambient air pollutants. Objectives: To examine all relevant human data evaluating a link between ambient pollution exposure and olfaction and to review supporting animal data in order to examine potential mechanisms for pollution-associated olfactory loss. Methods: We identified and reviewed relevant articles from 1950 to 2015 using PubMed and Web of Science and focusing on human epidemiologic and pathophysiologic studies. Animal studies were included only to support pertinent data on humans. We reviewed findings from these studies evaluating a relationship between environmental pollutant exposure and olfactory function. Results: We identified and reviewed 17 articles, with 1 additional article added from a bibliography search, for a total of 18 human studies. There is evidence in human epidemiologic and pathologic studies that increased exposure to ambient air pollutants is associated with olfactory dysfunction. However, most studies have used proxies for pollution exposure in small samples of convenience. Human pathologic studies, with supporting animal work, have also shown that air pollution can contact the olfactory epithelium, translocate to the olfactory bulb, and migrate to the olfactory cortex. Pollutants can deposit at each location, causing direct damage and disruption of tissue morphology or inducing local inflammation and cellular stress responses. Conclusions: Ambient air pollution may impact human olfactory function. Additional studies are needed to examine air pollution–related olfactory impacts on the general population using measured pollution exposures and to link pollution exposure with olfactory dysfunction and related pathology. Citation: Ajmani GS, Suh HH, Pinto JM. 2016. Effects of ambient air pollution exposure on olfaction: a review. Environ Health Perspect 124:1683–1693; http://dx.doi.org/10.1289/EHP136 PMID:27285588

Single olfactory organ associated with prosencephalic malformation and cyclopia in a Xenopus laevis tadpole.

PubMed

Magrassi, L; Graziadei, P P

1987-06-02

A cyclops Xenopus laevis tadpole with a single olfactory organ is described. At a stage comparable to 48, the telencephalon was severely atrophic and only the region where the olfactory fibres terminated appeared to have the cytoarchitecture of the olfactory bulb. In this animal the central nervous system (CNS) appeared normally developed only posterior to the preoptic area. The hypothesis of a diencephalic origin of the region where the olfactory fibres terminated is discussed in the light of our previous results of olfactory placode transplantation. By analogy between this case and other malformations (cyclopia, holoprosencephaly) in higher vertebrates and humans, the need is emphasized for a more precise anatomical description of the olfactory input in related malformations.

On the Communicative Function of Body Odors.

PubMed

de Groot, Jasper H B; Semin, Gün R; Smeets, Monique A M

2017-03-01

Humans use multiple senses to navigate the social world, and the sense of smell is arguably the most underestimated one. An intriguing aspect of the sense of smell is its social communicative function. Research has shown that human odors convey information about a range of states (e.g., emotions, sickness) and traits (e.g., individuality, gender). Yet, what underlies the communicability of these states and traits via smell? We fill this explanatory gap with a framework that highlights the dynamic and flexible aspects of human olfactory communication. In particular, we explain how chemical profiles, associative learning (i.e., the systematic co-occurrence of chemical profiles with state- or trait-related information), and top-down contextual influences could interact to shape human odor perception. Our model not only helps to integrate past research on human olfactory communication but it also opens new avenues for future research on this fascinating, yet to date poorly understood, field.

Modelling the emergence of rodent filial huddling from physiological huddling

NASA Astrophysics Data System (ADS)

Wilson, Stuart P.

2017-11-01

Huddling behaviour in neonatal rodents reduces the metabolic costs of physiological thermoregulation. However, animals continue to huddle into adulthood, at ambient temperatures where they are able to sustain a basal metabolism in isolation from the huddle. This `filial huddling' in older animals is known to be guided by olfactory rather than thermal cues. The present study aimed to test whether thermally rewarding contacts between young mice, experienced when thermogenesis in brown adipose fat tissue (BAT) is highest, could give rise to olfactory preferences that persist as filial huddling interactions in adults. To this end, a simple model was constructed to fit existing data on the development of mouse thermal physiology and behaviour. The form of the model that emerged yields a remarkable explanation for filial huddling; associative learning maintains huddling into adulthood via processes that reduce thermodynamic entropy from BAT metabolism and increase information about social ordering among littermates.

Noise facilitation in associative memories of exponential capacity.

PubMed

Karbasi, Amin; Salavati, Amir Hesam; Shokrollahi, Amin; Varshney, Lav R

2014-11-01

Recent advances in associative memory design through structured pattern sets and graph-based inference algorithms have allowed reliable learning and recall of an exponential number of patterns that satisfy certain subspace constraints. Although these designs correct external errors in recall, they assume neurons that compute noiselessly, in contrast to the highly variable neurons in brain regions thought to operate associatively, such as hippocampus and olfactory cortex. Here we consider associative memories with boundedly noisy internal computations and analytically characterize performance. As long as the internal noise level is below a specified threshold, the error probability in the recall phase can be made exceedingly small. More surprising, we show that internal noise improves the performance of the recall phase while the pattern retrieval capacity remains intact: the number of stored patterns does not reduce with noise (up to a threshold). Computational experiments lend additional support to our theoretical analysis. This work suggests a functional benefit to noisy neurons in biological neuronal networks.

Enhancing Academic Performance: Seven Perceptual Styles of Learning.

ERIC Educational Resources Information Center

Higbee, Jeanne L.; And Others

1991-01-01

Presents Galbraith and James's taxonomy of seven perceptual modalities (i.e., print, aural, interactive, visual, haptic, kinesthetic, and olfactory). Discusses ways educators can demonstrate perceptual modalities in the classroom and help students identify their personal style of learning. Explains how this knowledge can facilitate learning in a…

Olfactory Cleft Endoscopy Scale correlates with olfactory metrics in patients with chronic rhinosinusitis

PubMed Central

Soler, Zachary M.; Hyer, J. Madison; Karnezis, Tom T.; Schlosser, Rodney J.

2015-01-01

Introduction Olfactory loss affects a majority of patients with chronic rhinosinusitis (CRS). Traditional objective measures of disease severity, including endoscopy scales, focus upon the paranasal sinuses and often have weak correlation to olfaction. Methods Adults with CRS were prospectively evaluated by blinded reviewers with a novel Olfactory Cleft Endoscopy Scale (OCES) that evaluated discharge, polyps, edema, crusting and scarring of the olfactory cleft. Objective olfactory function was assessed using “Sniffin’ Sticks testing, including composite threshold-discrimination-identification (TDI) scores. Olfactory-specific quality-of-life was evaluated using the short modified version of the Questionnaire of Olfactory Disorders (QOD-NS). Inter- and intra-rater reliability was assessed among 3 reviewers for OCES grading. Multivariate linear regression was then used to test associations between OCES scores and measures of olfaction, controlling for potential confounding factors. Results The OCES score was evaluated in 38 patients and had a high overall reliability (ICC=0.92; 95% CI: 0.91–0.96). The OCES significantly correlated with objective olfaction as measured by TDI score (p<0.001), with TDI score falling by 1.13 points for every 1 point increase in OCES score. Similar significant associations were found for threshold, discrimination, and identification scores (p<0.003 for all) after controlling for age, gender, race, and reviewer/review. The OCES was also highly associated with patient-reported QOD-NS scores (p=0.009). Conclusion A novel olfactory cleft endoscopy scale shows high reliability and correlates with both objective and patient-reported olfaction in patients with CRS. Further studies to determine prognostic value and responsiveness to change are warranted. PMID:26718315

The functional divide for primary reinforcement of D-amphetamine lies between the medial and lateral ventral striatum: is the division of the accumbens core, shell, and olfactory tubercle valid?

PubMed

Ikemoto, Satoshi; Qin, Mei; Liu, Zhong-Hua

2005-05-18

When projection analyses placed the nucleus accumbens and olfactory tubercle in the striatal system, functional links between these sites began to emerge. The accumbens has been implicated in the rewarding effects of psychomotor stimulants, whereas recent work suggests that the medial accumbens shell and medial olfactory tubercle mediate the rewarding effects of cocaine. Interestingly, anatomical evidence suggests that medial portions of the shell and tubercle receive afferents from common zones in a number of regions. Here, we report results suggesting that the current division of the ventral striatum into the accumbens core and shell and the olfactory tubercle does not reflect the functional organization for amphetamine reward. Rats quickly learned to self-administer D-amphetamine into the medial shell or medial tubercle, whereas they failed to learn to do so into the accumbens core, ventral shell, or lateral tubercle. Our results suggest that primary reinforcement of amphetamine is mediated via the medial portion of the ventral striatum. Thus, the medial shell and medial tubercle are more functionally related than the medial and ventral shell or the medial and lateral tubercle. The current core-shell-tubercle scheme should be reconsidered in light of recent anatomical data and these functional findings.

The Evaluation of Olfactory Function in Patients With Schizophrenia.

PubMed

Robabeh, Soleimani; Mohammad, Jalali Mir; Reza, Ahmadi; Mahan, Badri

2015-04-23

The aim of this study was to compare olfactory threshold, smell identification, intensity and pleasantness ratings between patients with schizophrenia and healthy controls, and (2) to evaluate correlations between ratings of olfactory probes and illness characteristics. Thirty one patients with schizophrenia and 31 control subjects were assessed with the olfactory n-butanol threshold test, the Iran smell identification test (Ir-SIT), and the suprathreshold amyl acetate odor intensity and odor pleasantness rating test. All olfactory tasks were performed unirhinally. Patients with schizophrenia showed disrupted olfaction in all four measures. Longer duration of schizophrenia was associated with a larger impairment of olfactory threshold or microsmic range on the Ir-SIT (P=0.04, P=0.05, respectively). In patients with schizophrenia, female subjects' ratings of pleasantness followed the same trend as control subjects, whereas male patients' ratings showed an opposite trend. Patients exhibiting high positive score on the positive and negative syndrome scale (PANSS) performed better on the olfactory threshold test (r=0.37, P=0.04). The higher odor pleasantness ratings of patients were associated with presence of positive symptoms. The results suggest that both male and female patients with schizophrenia had difficulties on the olfactory threshold and smell identification tests, but appraisal of odor pleasantness was more disrupted in male patients.

The olfactory fascia: an evo-devo concept of the fibrocartilaginous nose.

PubMed

Jankowski, Roger; Rumeau, Cécile; de Saint Hilaire, Théophile; Tonnelet, Romain; Nguyen, Duc Trung; Gallet, Patrice; Perez, Manuela

2016-12-01

Evo-devo is the science that studies the link between evolution of species and embryological development. This concept helps to understand the complex anatomy of the human nose. The evo-devo theory suggests the persistence in the adult of an anatomical entity, the olfactory fascia, that unites the cartilages of the nose to the olfactory mucosa. We dissected two fresh specimens. After resecting the superficial tissues of the nose, dissection was focused on the disarticulation of the fibrocartilaginous noses from the facial and skull base skeleton. Dissection shows two fibrocartilaginous sacs that were invaginated side-by-side in the midface and attached to the anterior skull base. These membranous sacs were separated in the midline by the perpendicular plate of the ethmoid. Their walls contained the alar cartilages and the lateral expansions of the septolateral cartilage, which we had to separate from the septal cartilage. The olfactory mucosa was located inside their cranial ends. The olfactory fascia is a continuous membrane uniting the nasal cartilages to the olfactory mucosa. Its origin can be found in the invagination and differentiation processes of the olfactory placodes. The fibrous portions of the olfactory fascia may be described as ligaments that unit the different components of the olfactory fascia one to the other and the fibrocartilaginous nose to the facial and skull base skeleton. The basicranial ligaments, fixing the fibrocartilaginous nose to the skull base, represent key elements in the concept of septorhinoplasty by disarticulation.

Effect of circadian phase on memory acquisition and recall: operant conditioning vs. classical conditioning.

PubMed

Garren, Madeleine V; Sexauer, Stephen B; Page, Terry L

2013-01-01

There have been several studies on the role of circadian clocks in the regulation of associative learning and memory processes in both vertebrate and invertebrate species. The results have been quite variable and at present it is unclear to what extent the variability observed reflects species differences or differences in methodology. Previous results have shown that following differential classical conditioning in the cockroach, Rhyparobia maderae, in an olfactory discrimination task, formation of the short-term and long-term memory is under strict circadian control. In contrast, there appeared to be no circadian regulation of the ability to recall established memories. In the present study, we show that following operant conditioning of the same species in a very similar olfactory discrimination task, there is no impact of the circadian system on either short-term or long-term memory formation. On the other hand, ability to recall established memories is strongly tied to the circadian phase of training. On the basis of these data and those previously reported for phylogenetically diverse species, it is suggested that there may be fundamental differences in the way the circadian system regulates learning and memory in classical and operant conditioning.

Effect of Circadian Phase on Memory Acquisition and Recall: Operant Conditioning vs. Classical Conditioning

PubMed Central

Garren, Madeleine V.; Sexauer, Stephen B.; Page, Terry L.

2013-01-01

There have been several studies on the role of circadian clocks in the regulation of associative learning and memory processes in both vertebrate and invertebrate species. The results have been quite variable and at present it is unclear to what extent the variability observed reflects species differences or differences in methodology. Previous results have shown that following differential classical conditioning in the cockroach, Rhyparobia maderae, in an olfactory discrimination task, formation of the short-term and long-term memory is under strict circadian control. In contrast, there appeared to be no circadian regulation of the ability to recall established memories. In the present study, we show that following operant conditioning of the same species in a very similar olfactory discrimination task, there is no impact of the circadian system on either short-term or long-term memory formation. On the other hand, ability to recall established memories is strongly tied to the circadian phase of training. On the basis of these data and those previously reported for phylogenetically diverse species, it is suggested that there may be fundamental differences in the way the circadian system regulates learning and memory in classical and operant conditioning. PMID:23533587

Changes in olfactory bulb volume following lateralized olfactory training.

PubMed

Negoias, S; Pietsch, K; Hummel, T

2017-08-01

Repeated exposure to odors modifies olfactory function. Consequently, "olfactory training" plays a significant role in hyposmia treatment. In addition, numerous studies show that the olfactory bulb (OB) volume changes in disorders associated with olfactory dysfunction. Aim of this study was to investigate whether and how olfactory bulb volume changes in relation to lateralized olfactory training in healthy people. Over a period of 4 months, 97 healthy participants (63 females and 34 males, mean age: 23.74 ± 4.16 years, age range: 19-43 years) performed olfactory training by exposing the same nostril twice a day to 4 odors (lemon, rose, eucalyptus and cloves) while closing the other nostril. Before and after olfactory training, magnetic resonance imaging (MRI) scans were performed to measure OB volume. Furthermore, participants underwent lateralized odor threshold and odor identification testing using the "Sniffin' Sticks" test battery.OB volume increased significantly after olfactory training (11.3 % and 13.1 % respectively) for both trained and untrained nostril. No significant effects of sex, duration and frequency of training or age of the subjects were seen. Interestingly, PEA odor thresholds worsened after training, while olfactory identification remained unchanged.These data show for the first time in humans that olfactory training may involve top-down process, which ultimately lead to a bilateral increase in olfactory bulb volume.

Association Between Olfactory Dysfunction and Amnestic Mild Cognitive Impairment and Alzheimer Disease Dementia

PubMed Central

Roberts, Rosebud O.; Christianson, Teresa J. H.; Kremers, Walter K.; Mielke, Michelle M.; Machulda, Mary M.; Vassilaki, Maria; Alhurani, Rabe E.; Geda, Yonas E.; Knopman, David S.; Petersen, Ronald C.

2015-01-01

IMPORTANCE To increase the opportunity to delay or prevent mild cognitive impairment (MCI) or dementia due to Alzheimer's disease (AD), markers of early detection are essential. Olfactory impairment may be an important clinical marker and predictor of these conditions and may help identify persons at increased risk. OBJECTIVE To examine associations of impaired olfaction with incident MCI subtypes, and progression from MCI subtypes to AD dementia. DESIGN, SETTING, AND PARTICIPANTS Participants enrolled in the population-based, prospective Mayo Clinic Study of Aging were clinically evaluated at baseline and every 15-months thereafter, and classified as having normal cognition, MCI (amnestic, aMCI and nonamnestic, naMCI), and dementia. We administered the Brief Smell Identification Test (B-SIT) to assess olfactory function. MAIN OUTCOMES AND MEASURES Mild cognitive impairment, AD dementia, longitudinal change in cognitive performance measures. RESULTS Over a mean 3.5 years of follow-up, there were 250 incident cases of MCI among 1430 cognitively normal participants. We observed an association between decreasing olfactory identification, as measured by decrease in number of correct responses in B-SIT score, and an increased risk of aMCI. Compared to the upper B-SIT quartile (Q4, best scores), hazard ratios (HR) were 1.12; P = 0.68 for Q3; HR, 1.95; P =0.003 for Q2; and HR, 2.18; P = 0.001 (worst scores; p for trend <0.001) after adjustment for sex and education, with age as the time scale. There was no association with naMCI. There were 64 incident dementia cases among 221 prevalent MCI cases. The B-SIT score also predicted progression from aMCI to AD, with a significant dose-response with worsening B-SIT quartiles. Compared to Q4, HR estimates were 3.02, P = 0.038 for Q3; HR, 3.63; P = 0.024 for Q2; and HR, 5.20; P = 0.001 for Q1. After adjusting for key predictors of MCI risk, B-SIT (as a continuous measure) remained a significant predictor of MCI (HR, 1.10; p < 0.001), and improved the model concordance. CONCLUSIONS AND RELEVANCE Olfactory impairment predicts incident aMCI and progression from aMCI to AD. These findings are consistent with previous studies that have reported associations of olfactory impairment with cognitive impairment in late life, and suggest that olfactory tests have potential utility for screening for MCI and MCI that is likely to progress. PMID:26569387

The reluctant visitor: an alkaloid in toxic nectar can reduce olfactory learning and memory in Asian honey bees.

PubMed

Zhang, Junjun; Wang, Zhengwei; Wen, Ping; Qu, Yufeng; Tan, Ken; Nieh, James C

2018-03-01

The nectar of the thunder god vine, Tripterygium hypoglaucum , contains a terpenoid, triptolide (TRP), that may be toxic to the sympatric Asian honey bee, Apis cerana , because honey produced from this nectar is toxic to bees. However, these bees will forage on, recruit for, and pollinate this plant during a seasonal dearth of preferred food sources. Olfactory learning plays a key role in forager constancy and pollination, and we therefore tested the effects of acute and chronic TRP feeding on forager olfactory learning, using proboscis extension reflex conditioning. At concentrations of 0.5-10 µg TRP ml -1 , there were no learning effects of acute exposure. However, memory retention (1 h after the last learning trial) significantly decreased by 56% following acute consumption of 0.5 µg TRP ml -1 Chronic exposure did not alter learning or memory, except at high concentrations (5 and 10 µg TRP ml -1 ). TRP concentrations in nectar may therefore not significantly harm plant pollination. Surprisingly, TRP slightly increased bee survival, and thus other components in T. hypoglaucum honey may be toxic. Long-term exposure to TRP could have colony effects but these may be ameliorated by the bees' aversion to T. hypoglaucum nectar when other food sources are available and, perhaps, by detoxification mechanisms. The co-evolution of this plant and its reluctant visitor may therefore likely illustrate a classic compromise between the interests of both actors. © 2018. Published by The Company of Biologists Ltd.

Activity-dependent expression of miR-132 regulates immediate-early gene induction during olfactory learning in the greater short-nosed fruit bat, Cynopterus sphinx.

PubMed

Mukilan, Murugan; Ragu Varman, Durairaj; Sudhakar, Sivasubramaniam; Rajan, Koilmani Emmanuvel

2015-04-01

The activity-dependent expression of immediate-early genes (IEGs) and microRNA (miR)-132 has been implicated in synaptic plasticity and the formation of long-term memory (LTM). In the present study, we show that olfactory training induces the expression of IEGs (EGR-1, C-fos, C-jun) and miR-132 at similar time scale in olfactory bulb (OB) of Cynopterus sphinx. We examined the role of miR-132 in the OB using antisense oligodeoxynucleotide (AS-ODN) and demonstrated that a local infusion of AS-ODN in the OB 2h prior to training impaired olfactory memory formation in C. sphinx. However, the infusion of AS-ODN post-training did not cause a deficit in memory formation. Furthermore, the inhibition of miR-132 reduced the olfactory training-induced expression of IEGs and post synaptic density protein-95 (PSD-95) in the OB. Additionally, we show that miR-132 regulates the activation of calcium/calmodulin-dependent protein kinase-II (CaMKII) and cAMP response element binding protein (CREB), possibly through miR-148a. These data suggest that olfactory training induces the expression of miR-132 and IEGs, which in turn activates post-synaptic proteins that regulate olfactory memory formation. Copyright © 2015 Elsevier Inc. All rights reserved.

Olfactory Dysfunction in Patients With CNGB1-Associated Retinitis Pigmentosa.

PubMed

Charbel Issa, Peter; Reuter, Peggy; Kühlewein, Laura; Birtel, Johannes; Gliem, Martin; Tropitzsch, Anke; Whitcroft, Katherine L; Bolz, Hanno J; Ishihara, Kenji; MacLaren, Robert E; Downes, Susan M; Oishi, Akio; Zrenner, Eberhart; Kohl, Susanne; Hummel, Thomas

2018-05-24

Co-occurrence of retinitis pigmentosa (RP) and olfactory dysfunction may have a common genetic cause. To report olfactory function and the retinal phenotype in patients with biallelic mutations in CNGB1, a gene coding for a signal transduction channel subunit expressed in rod photoreceptors and olfactory sensory neurons. This case series was conducted from August 2015 through July 2017. The setting was a multicenter study involving 4 tertiary referral centers for inherited retinal dystrophies. Participants were 9 patients with CNGB1-associated RP. Results of olfactory testing, ocular phenotyping, and molecular genetic testing using targeted next-generation sequencing. Nine patients were included in the study, 3 of whom were female. Their ages ranged between 34 and 79 years. All patients had an early onset of night blindness but were usually not diagnosed as having RP before the fourth decade because of slow retinal degeneration. Retinal features were characteristic of a rod-cone dystrophy. Olfactory testing revealed reduced or absent olfactory function, with all except one patient scoring in the lowest quartile in relation to age-related norms. Brain magnetic resonance imaging and electroencephalography measurements in response to olfactory stimulation were available for 1 patient and revealed no visible olfactory bulbs and reduced responses to odor, respectively. Molecular genetic testing identified 5 novel (c.1312C>T, c.2210G>A, c.2492+1G>A, c.2763C>G, and c.3044_3050delGGAAATC) and 5 previously reported mutations in CNGB1. Mutations in CNGB1 may cause an autosomal recessive RP-olfactory dysfunction syndrome characterized by a slow progression of retinal degeneration and variable anosmia or hyposmia.

A Pilot Study of the Snap & Sniff Threshold Test.

PubMed

Jiang, Rong-San; Liang, Kai-Li

2018-05-01

The Snap & Sniff ® Threshold Test (S&S) has been recently developed to determine the olfactory threshold. The aim of this study was to further evaluate the validity and test-retest reliability of the S&S. The olfactory thresholds of 120 participants were determined using both the Smell Threshold Test (STT) and the S&S. The participants included 30 normosmic volunteers and 90 patients (60 hyposmic, 30 anosmic). The normosmic participants were retested using the STT and S&S at an intertest interval of at least 1 day. The mean olfactory threshold determined with the S&S was -6.76 for the normosmic participants, -3.79 for the hyposmic patients, and -2 for the anosmic patients. The olfactory thresholds were significantly different across the 3 groups ( P < .001). Snap & Sniff-based and STT-based olfactory thresholds were correlated weakly in the normosmic group (correlation coefficient = 0.162, P = .391) but more strongly correlated in the patient groups (hyposmic: correlation coefficient = 0.376, P = .003; anosmic: correlation coefficient = 1.0). The test-retest correlation for the S&S-based olfactory thresholds was 0.384 ( P = .036). Based on validity and test-retest reliability, we concluded that the S&S is a proper test for olfactory thresholds.

Behavioral and neural plasticity caused by early social experiences: the case of the honeybee

PubMed Central

Arenas, Andrés; Ramírez, Gabriela P.; Balbuena, María Sol; Farina, Walter M.

2013-01-01

Cognitive experiences during the early stages of life play an important role in shaping future behavior. Behavioral and neural long-term changes after early sensory and associative experiences have been recently reported in the honeybee. This invertebrate is an excellent model for assessing the role of precocious experiences on later behavior due to its extraordinarily tuned division of labor based on age polyethism. These studies are mainly focused on the role and importance of experiences occurred during the first days of the adult lifespan, their impact on foraging decisions, and their contribution to coordinate food gathering. Odor-rewarded experiences during the first days of honeybee adulthood alter the responsiveness to sucrose, making young hive bees more sensitive to assess gustatory features about the nectar brought back to the hive and affecting the dynamic of the food transfers and the propagation of food-related information within the colony. Early olfactory experiences lead to stable and long-term associative memories that can be successfully recalled after many days, even at foraging ages. Also they improve memorizing of new associative learning events later in life. The establishment of early memories promotes stable reorganization of the olfactory circuits inducing structural and functional changes in the antennal lobe (AL). Early rewarded experiences have relevant consequences at the social level too, biasing dance and trophallaxis partner choice and affecting recruitment. Here, we revised recent results in bees' physiology, behavior, and sociobiology to depict how the early experiences affect their cognition abilities and neural-related circuits. PMID:23986708

The neuronal architecture of the mushroom body provides a logic for associative learning

PubMed Central

Aso, Yoshinori; Hattori, Daisuke; Yu, Yang; Johnston, Rebecca M; Iyer, Nirmala A; Ngo, Teri-TB; Dionne, Heather; Abbott, LF; Axel, Richard; Tanimoto, Hiromu; Rubin, Gerald M

2014-01-01

We identified the neurons comprising the Drosophila mushroom body (MB), an associative center in invertebrate brains, and provide a comprehensive map describing their potential connections. Each of the 21 MB output neuron (MBON) types elaborates segregated dendritic arbors along the parallel axons of ∼2000 Kenyon cells, forming 15 compartments that collectively tile the MB lobes. MBON axons project to five discrete neuropils outside of the MB and three MBON types form a feedforward network in the lobes. Each of the 20 dopaminergic neuron (DAN) types projects axons to one, or at most two, of the MBON compartments. Convergence of DAN axons on compartmentalized Kenyon cell–MBON synapses creates a highly ordered unit that can support learning to impose valence on sensory representations. The elucidation of the complement of neurons of the MB provides a comprehensive anatomical substrate from which one can infer a functional logic of associative olfactory learning and memory. DOI: http://dx.doi.org/10.7554/eLife.04577.001 PMID:25535793

Olfaction in Endoscopic Sinus and Skull Base Surgery.

PubMed

Thompson, Christopher F; Kern, Robert C; Conley, David B

2015-10-01

Olfactory dysfunction is a common complaint for patients with chronic rhinosinusitis, because smell loss decreases a patient's quality of life. Smell loss is caused by obstruction from polyps, nasal discharge, and mucosal edema, as well as inflammatory changes within the olfactory epithelium. Addressing olfaction before endoscopic sinus and skull base surgery is important in order to set postoperative expectations, because an improvement in smell is difficult to predict. Several commercially available olfactory testing measures are available and can easily be administered in clinic. During surgery, careful dissection within the olfactory cleft is recommended in order to optimize postoperative olfactory function. Copyright © 2015 Elsevier Inc. All rights reserved.

Odour discrimination learning in the Indian greater short-nosed fruit bat (Cynopterus sphinx): differential expression of Egr-1, C-fos and PP-1 in the olfactory bulb, amygdala and hippocampus.

PubMed

Mukilan, Murugan; Bogdanowicz, Wieslaw; Marimuthu, Ganapathy; Rajan, Koilmani Emmanuvel

2018-06-15

Activity-dependent expression of immediate-early genes (IEGs) is induced by exposure to odour. The present study was designed to investigate whether there is differential expression of IEGs ( Egr-1 , C-fos ) in the brain region mediating olfactory memory in the Indian greater short-nosed fruit bat, Cynopterus sphinx We assumed that differential expression of IEGs in different brain regions may orchestrate a preference odour (PO) and aversive odour (AO) memory in C. sphinx We used preferred (0.8% w/w cinnamon powder) and aversive (0.4% w/v citral) odour substances, with freshly prepared chopped apple, to assess the behavioural response and induction of IEGs in the olfactory bulb, hippocampus and amygdala. After experiencing PO and AO, the bats initially responded to both, later only engaging in feeding bouts in response to the PO food. The expression pattern of EGR-1 and c-Fos in the olfactory bulb, hippocampus and amygdala was similar at different time points (15, 30 and 60 min) following the response to PO, but was different for AO. The response to AO elevated the level of c-Fos expression within 30 min and reduced it at 60 min in both the olfactory bulb and the hippocampus, as opposed to the continuous increase noted in the amygdala. In addition, we tested whether an epigenetic mechanism involving protein phosphatase-1 (PP-1) acts on IEG expression. The observed PP-1 expression and the level of unmethylated/methylated promoter revealed that C-fos expression is possibly controlled by odour-mediated regulation of PP-1. These results in turn imply that the differential expression of C-fos in the hippocampus and amygdala may contribute to olfactory learning and memory in C. sphinx . © 2018. Published by The Company of Biologists Ltd.

Interglomerular Connectivity within the Canonical and GC-D/Necklace Olfactory Subsystems

PubMed Central

Puche, Adam C.; Munger, Steven D.

2016-01-01

The mammalian main olfactory system contains several subsystems that differ not only in the receptors they express and the glomerular targets they innervate within the main olfactory bulb (MOB), but also in the strategies they use to process odor information. The canonical main olfactory system employs a combinatorial coding strategy that represents odorant identity as a pattern of glomerular activity. By contrast, the "GC-D/necklace" olfactory subsystem—formed by olfactory sensory neurons expressing the receptor guanylyl cyclase GC-D and their target necklace glomeruli (NGs) encircling the caudal MOB—is critical for the detection of a small number of semiochemicals that promote the acquisition of food preferences. The formation of these socially-transmitted food preferences requires the animal to integrate information about two types of olfactory stimuli: these specialized social chemosignals and the food odors themselves. However, the neural mechanisms with which the GC-D/necklace subsystem processes this information are unclear. We used stimulus-induced increases in intrinsic fluorescence signals to map functional circuitry associated with NGs and canonical glomeruli (CGs) in the MOB. As expected, CG-associated activity spread laterally through both the glomerular and external plexiform layers associated with activated glomeruli. Activation of CGs or NGs resulted in activity spread between the two types of glomeruli; there was no evidence of preferential connectivity between individual necklace glomeruli. These results support previous anatomical findings that suggest the canonical and GC-D/necklace subsystems are functionally connected and may integrate general odor and semiochemical information in the MOB. PMID:27902696

The olfactory gonadotropin-releasing hormone immunoreactive system in mouse.

PubMed

Jennes, L

1986-10-29

The olfactory gonadotropin-releasing hormone (GnRH) system in mice was studied with immunofluorescence in combination with lesions of the olfactory bulb and retrograde transport of horseradish peroxidase (HRP) which was administered intravascularly, intranasally or into the subarachnoid space. GnRH-positive neurons were located in the two major branches forming the septal roots of the nervus terminalis, in the ganglion terminale, within the fascicles of the nervus terminalis throughout its extent, in a conspicuous band which connects the ventral neck of the caudal olfactory bulb with the accessory olfactory bulb and in the nasal mucosa. GnRH-positive fibers were seen in all areas in which neurons were found, i.e. in the rostral septum, the ganglion and nervus terminalis and in the nasal subepithelium. In addition, a broad bundle of fibers was observed to surround the entire caudal olfactory bulb, connecting the rostral sulcus rhinalis with the ventrocaudal olfactory bulb. Fibers were seen in close association with the main and accessory olfactory bulb, with the fila olfactoria and with the nasal mucosa. Throughout the olfactory bulb and the nasal epithelium, an association of GnRH fibers with blood vessels was apparent. Intravascular and intranasal injection of HRP resulted in labeling of certain GnRH neurons in the septal roots of the nervus terminalis, the ganglion terminale, the nervus terminalis, the caudal ventrodorsal connection and in the accessory olfactory bulb. After placement of HRP into the subarachnoid space dorsal to the accessory olfactory bulb, about 50% of the GnRH neurons in the accessory olfactory bulb and in the ventrodorsal connection were labeled with HRP. Also, a few GnRH neurons in the rostral septum, the ganglion terminale and in the fascicles of the nervus terminalis had taken up the enzyme. Lesions of the nervus terminalis caudal to the ganglion terminale resulted in sprouting of GnRH fibers at both sites of the knife cut. Lesions rostral to the ganglion terminale induced sprouting mostly at the distal site of the knife cut while most but not all GnRH fibers proximal to the lesion had disappeared. The results of the present study indicate that the olfactory GnRH system is mostly associated with the nervus terminalis. This cranial nerve apparently projects to the central nervous system as well as the periphery. The results of the HRP uptake studies suggest that the GnRH neurons in the nervus terminalis have access to fenestrated capillaries in the subepithelial connective tissue of the nasal mucosa, to the nasal epithelium proper, and to the subarachnoid space.(ABSTRACT TRUNCATED AT 400 WORDS)

Disrupted Olfactory Integration in Schizophrenia: Functional Connectivity Study.

PubMed

Kiparizoska, Sara; Ikuta, Toshikazu

2017-09-01

Evidence for olfactory dysfunction in schizophrenia has been firmly established. However, in the typical understanding of schizophrenia, olfaction is not recognized to contribute to or interact with the illness. Despite the solid presence of olfactory dysfunction in schizophrenia, its relation to the rest of the illness remains largely unclear. Here, we aimed to examine functional connectivity of the olfactory bulb, olfactory tract, and piriform cortices and isolate the network that would account for the altered olfaction in schizophrenia. We examined the functional connectivity of these specific olfactory regions in order to isolate other brain regions associated with olfactory processing in schizophrenia. Using the resting state functional MRI data from the Center for Biomedical Research Excellence in Brain Function and Mental Illness, we compared 84 patients of schizophrenia and 90 individuals without schizophrenia. The schizophrenia group showed disconnectivity between the anterior piriform cortex and the nucleus accumbens, between the posterior piriform cortex and the middle frontal gyrus, and between the olfactory tract and the visual cortices. The current results suggest functional disconnectivity of olfactory regions in schizophrenia, which may account for olfactory dysfunction and disrupted integration with other sensory modalities in schizophrenia. © The Author 2017. Published by Oxford University Press on behalf of CINP.

Olfactory function and malnutrition in geriatric patients.

PubMed

Smoliner, Christine; Fischedick, Andrea; Sieber, Cornel C; Wirth, Rainer

2013-12-01

Impaired olfaction is considered to be a risk factor for malnutrition in older adults; however, there is little research on this association. The aim of this study was to investigate whether olfactory deficits are associated with an impaired nutritional status in older patients. Study participants were recruited from a geriatric day hospital. Nutritional status was assessed with body mass index and Mini-Nutritional Assessment. Olfactory function was evaluated with the Sniffin' Sticks test (SST) and subjectively rated by the patient. Self-caring capacity was rated with the Barthel Index and cognitive status with the Mini-Mental State Examination. One hundred ninety-one patients, 71.7% female, were included with a mean age of 79.6 ± 6.3 years. Prevalence of hyposmia was 39.3%, and 31.9% of patients were functionally anosmic. Malnourished patients did not have a significantly lower Sniffin' Sticks test score than patients at nutritional risk or malnourished patients. In linear regression analysis, nutritional status was only influenced by Barthel Index, age, and number of drugs but not by olfactory function. In this sample, olfactory function was not associated with nutritional status.

Cholinergic Inputs from Basal Forebrain Add an Excitatory Bias to Odor Coding in the Olfactory Bulb

PubMed Central

Rothermel, Markus; Carey, Ryan M.; Puche, Adam; Shipley, Michael T.

2014-01-01

Cholinergic modulation of central circuits is associated with active sensation, attention, and learning, yet the neural circuits and temporal dynamics underlying cholinergic effects on sensory processing remain unclear. Understanding the effects of cholinergic modulation on particular circuits is complicated by the widespread projections of cholinergic neurons to telencephalic structures that themselves are highly interconnected. Here we examined how cholinergic projections from basal forebrain to the olfactory bulb (OB) modulate output from the first stage of sensory processing in the mouse olfactory system. By optogenetically activating their axons directly in the OB, we found that cholinergic projections from basal forebrain regulate OB output by increasing the spike output of presumptive mitral/tufted cells. Cholinergic stimulation increased mitral/tufted cell spiking in the absence of inhalation-driven sensory input and further increased spiking responses to inhalation of odorless air and to odorants. This modulation was rapid and transient, was dependent on local cholinergic signaling in the OB, and differed from modulation by optogenetic activation of cholinergic neurons in basal forebrain, which led to a mixture of mitral/tufted cell excitation and suppression. Finally, bulbar cholinergic enhancement of mitral/tufted cell odorant responses was robust and occurred independent of the strength or even polarity of the odorant-evoked response, indicating that cholinergic modulation adds an excitatory bias to mitral/tufted cells as opposed to increasing response gain or sharpening response spectra. These results are consistent with a role for the basal forebrain cholinergic system in dynamically regulating the sensitivity to or salience of odors during active sensing of the olfactory environment. PMID:24672011

Nasal polyposis (or chronic olfactory rhinitis).

PubMed

Jankowski, R; Rumeau, C; Gallet, P; Nguyen, D T

2018-06-01

The concept of chronic rhinosinusitis with or without polyps is founded on the structural and functional unicity of the pituitary mucosa and its united response to environmental aggression by allergens, viruses, bacteria, pollution, etc. The present review sets this concept against the evo-devo three-nose theory, in which nasal polyposis is distinguished as specific to the olfactory nose and in particular to the non-olfactory mucosa of the ethmoid, which is considered to be not a sinus but rather the skull-base bone harboring the olfactory mucosa. The evo-devo approach enables simple and precise positive diagnosis of nasal polyposis and its various clinical forms, improves differential diagnosis by distinguishing chronic diseases of the respiratory nose and those of the paranasal sinuses, hypothesizes an autoimmune origin specifically aimed at olfactory system auto-antigens, and supports the surgical concept of nasalization against that of functional sinus and ostiomeatal-complex surgery. The ventilation function of the sinuses seems minor compared to their production, storage and active release of nitric oxide (NO) serving to oxygenate arterial blood in the pulmonary alveoli. This respiratory function of the paranasal sinuses may indeed be their most important. NO trapped in the ethmoidal spaces also accounts for certain radiographic aspects associated with nasal polyposis. Copyright © 2018. Published by Elsevier Masson SAS.

Giant Olfactory Meningiomas

PubMed Central

d'Avella, Domenico; Salpietro, Francesco M.; Alafaci, Cetty; Tomasello, Francesco

1999-01-01

Olfactory groove meningiomas may attain surprisingly large size. The subfrontal approach is currently the route preferred by most neurosurgeons for their excision. The pterional-transsylvian route represents an alternate exposure for microsurgery of frontobasal tumors. Although this approach has been already described for olfactory meningiomas, tumors of giant size were not specifically addressed in the literature. We report the application of the pterional-transsylvian approach in six patients with giant olfactory meningiomas. This series is unique because it includes only patients with tumors exceeding 6 cm in diameter with bilateral symmetrical development. A radical removal was achieved in all patients and all of them made a full recovery. To investigate the relevance of the pterional-transsylvian approach for minimizing surgical morbidity, a magnetic resonance imaging protocol was designed to characterize even subtle postoperative frontal lobe structural changes. These changes, limited to the frontal lobe ipsilateral to exposure and localized in specific anatomical domains of the prefrontal area, included cystic degenerative alterations, parenchymal gliosis, and associated persistent white matter edema. Results from the present series strengthen the usefulness of the pterional-transsylvian approach as a safe surgical route for lesions affecting the anterior skull base, even with huge bilateral symmetrical expansion, such as giant olfactory meningiomas. ImagesFigure 1Figure 2Figure 3p26-bFigure 4p27-bFigure 5Figure 6Figure 7 PMID:17171078

Neural correlates of water reward in thirsty Drosophila

PubMed Central

Lin, Suewei; Owald, David; Chandra, Vikram; Talbot, Clifford; Huetteroth, Wolf; Waddell, Scott

2014-01-01

Drinking water is innately rewarding to thirsty animals. In addition, the consumed value can be assigned to behavioral actions and predictive sensory cues by associative learning. Here we show that thirst converts water avoidance into water-seeking in naïve Drosophila. Thirst also permits flies to learn olfactory cues paired with water reward. Water learning requires water taste and <40 water-responsive dopaminergic neurons that innervate a restricted zone of the mushroom body γ lobe. These water learning neurons are different from those that are critical to convey the reinforcing effects of sugar. Naïve water-seeking behavior in thirsty flies does not require water taste but relies on another subset of water-responsive dopaminergic neurons that target the mushroom body β′ lobe. Furthermore, these naïve water-approach neurons are not required for learned water-seeking. Our results therefore demonstrate that naïve and learned water-seeking, and water learning, utilize separable neural circuitry in the brain of thirsty flies. PMID:25262493

The relationship between smell identification and neuropsychological domains: Results from a sample of community-dwelling adults suspected of dementia.

PubMed

Goette, William F; Werry, Amy E; Schmitt, Andrew L

2018-08-01

This study aimed to test the theoretical relationships between smell identification and cognitive tasks based on existing neuroimaging and anatomical findings. Utilizing data collected from a memory assessment clinic, theory-derived mediation and moderation models were tested. The sample used in this study consisted of 103 (39 male, 64 female) individuals referred for memory assessments. The sample's mean education was 12.4 years (SD = 3.2), and the mean age of the sample was 77.2 years (SD = 6.3). The University of Pennsylvania Smell Identification Test (UPSIT) was a significant, partial mediator of the relationship between the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) Immediate and Delayed Memory indexes. Olfactory identification did not mediate list learning and retrieval; however, olfactory identification was a significant partial mediator of the relationship between story encoding and later memory retrieval of the story. Olfactory identification also fully mediated the relationship between a visuospatial construction task and its reconstruction from memory after a short delay. The relationship between processing speed and the olfactory identification was significantly mediated by semantic memory. Finally, the UPSIT moderated the relationship between a measure of premorbid ability, the Wechsler Test of Adult Reading, and current global cognitive functioning. Our results support theoretical relationships between olfaction and neuropsychological domains. Additionally, our results suggest that the UPSIT may serve as a proxy for cerebral integrity and is likely related to the duration of neurodegeneration.

Olfactory Function and Associated Clinical Correlates in Former National Football League Players

PubMed Central

Alosco, Michael L.; Jarnagin, Johnny; Tripodis, Yorghos; Platt, Michael; Martin, Brett; Chaisson, Christine E.; Baugh, Christine M.; Fritts, Nathan G.; Cantu, Robert C.

2017-01-01

Abstract Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. Olfactory dysfunction is a frequent early sequelae of neurodegenerative diseases (e.g., Alzheimer's disease), and RHI is associated with the neurodegenerative disease, chronic traumatic encephalopathy (CTE). We examined olfaction, and its association with clinical measures, in former National Football League (NFL) players. Ninety-five former NFL players (ages 40–69) and 28 same-age controls completed a neuropsychological and neuropsychiatric evaluation as part of a National Institutes of Health–funded study. The Brief Smell Identification Test (B-SIT) assessed olfaction. Principal component analysis generated a four-factor structure of the clinical measures: behavioral/mood, psychomotor speed/executive function, and verbal and visual memory. Former NFL players had worse B-SIT scores relative to controls (p = 0.0096). A B-SIT cutoff of 11 had the greatest accuracy (c-statistic = 0.61) and specificity (79%) for discriminating former NFL players from controls. In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction. PMID:27430424

Olfactory Function and Associated Clinical Correlates in Former National Football League Players.

PubMed

Alosco, Michael L; Jarnagin, Johnny; Tripodis, Yorghos; Platt, Michael; Martin, Brett; Chaisson, Christine E; Baugh, Christine M; Fritts, Nathan G; Cantu, Robert C; Stern, Robert A

2017-02-15

Professional American football players incur thousands of repetitive head impacts (RHIs) throughout their lifetime. The long-term consequences of RHI are not well characterized, but may include olfactory dysfunction. RHI has been associated with changes to brain regions involved in olfaction, and olfactory impairment is common after traumatic brain injury. Olfactory dysfunction is a frequent early sequelae of neurodegenerative diseases (e.g., Alzheimer's disease), and RHI is associated with the neurodegenerative disease, chronic traumatic encephalopathy (CTE). We examined olfaction, and its association with clinical measures, in former National Football League (NFL) players. Ninety-five former NFL players (ages 40-69) and 28 same-age controls completed a neuropsychological and neuropsychiatric evaluation as part of a National Institutes of Health-funded study. The Brief Smell Identification Test (B-SIT) assessed olfaction. Principal component analysis generated a four-factor structure of the clinical measures: behavioral/mood, psychomotor speed/executive function, and verbal and visual memory. Former NFL players had worse B-SIT scores relative to controls (p = 0.0096). A B-SIT cutoff of 11 had the greatest accuracy (c-statistic = 0.61) and specificity (79%) for discriminating former NFL players from controls. In the former NFL players, lower B-SIT scores correlated with greater behavioral/mood impairment (p = 0.0254) and worse psychomotor speed/executive functioning (p = 0.0464) after controlling for age and education. Former NFL players exhibited lower olfactory test scores relative to controls, and poorer olfactory test performance was associated with worse neuropsychological and neuropsychiatric functioning. Future work that uses more-comprehensive tests of olfaction and structural and functioning neuroimaging may improve understanding on the association between RHI and olfaction.

Loss of olfactory function and nutritional status in vital older adults and geriatric patients.

PubMed

Toussaint, Nicole; de Roon, Margot; van Campen, Jos P C M; Kremer, Stefanie; Boesveldt, Sanne

2015-03-01

The aim of this cross-sectional study was to assess the association of olfactory function and nutritional status in vital older adults and geriatric patients. Three hundred forty-five vital (mean age 67.1 years) and 138 geriatric older adults (mean age 80.9 years) were included. Nutritional status was assessed using the mini nutritional assessment-short form. The Sniffin' Sticks was used to measure olfactory function. Eleven percentage of the vital older adults were at risk of malnutrition, whereas 60% of the geriatric participants were malnourished or at risk. Only 2% of the vital older adults were anosmic, compared with 46% of the geriatric participants. Linear regression demonstrated a significant association (P = 0.015) between olfactory function and nutritional status in the geriatric subjects. However, this association became insignificant after adjustment for confounders. Both crude and adjusted analysis in the vital older adults did not show a significant association. The results indicate that, in both groups of elderly, there is no direct relation between olfactory function and nutritional status. We suggest that a decline in olfactory function may still be considered as one of the risk-factors for malnutrition in geriatric patients-once co-occurring with other mental and/or physical problems that are more likely to occur in those patients experience. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

PKA increases in the olfactory bulb act as unconditioned stimuli and provide evidence for parallel memory systems: pairing odor with increased PKA creates intermediate- and long-term, but not short-term, memories.

PubMed

Grimes, Matthew T; Harley, Carolyn W; Darby-King, Andrea; McLean, John H

2012-02-21

Neonatal odor-preference memory in rat pups is a well-defined associative mammalian memory model dependent on cAMP. Previous work from this laboratory demonstrates three phases of neonatal odor-preference memory: short-term (translation-independent), intermediate-term (translation-dependent), and long-term (transcription- and translation-dependent). Here, we use neonatal odor-preference learning to explore the role of olfactory bulb PKA in these three phases of mammalian memory. PKA activity increased normally in learning animals 10 min after a single training trial. Inhibition of PKA by Rp-cAMPs blocked intermediate-term and long-term memory, with no effect on short-term memory. PKA inhibition also prevented learning-associated CREB phosphorylation, a transcription factor implicated in long-term memory. When long-term memory was rescued through increased β-adrenoceptor activation, CREB phosphorylation was restored. Intermediate-term and long-term, but not short-term odor-preference memories were generated by pairing odor with direct PKA activation using intrabulbar Sp-cAMPs, which bypasses β-adrenoceptor activation. Higher levels of Sp-cAMPs enhanced memory by extending normal 24-h retention to 48-72 h. These results suggest that increased bulbar PKA is necessary and sufficient for the induction of intermediate-term and long-term odor-preference memory, and suggest that PKA activation levels also modulate memory duration. However, short-term memory appears to use molecular mechanisms other than the PKA/CREB pathway. These mechanisms, which are also recruited by β-adrenoceptor activation, must operate in parallel with PKA activation.

Artificial Induction of Associative Olfactory Memory by Optogenetic and Thermogenetic Activation of Olfactory Sensory Neurons and Octopaminergic Neurons in Drosophila Larvae

PubMed Central

Honda, Takato; Lee, Chi-Yu; Honjo, Ken; Furukubo-Tokunaga, Katsuo

2016-01-01

The larval brain of Drosophila melanogaster provides an excellent system for the study of the neurocircuitry mechanism of memory. Recent development of neurogenetic techniques in fruit flies enables manipulations of neuronal activities in freely behaving animals. This protocol describes detailed steps for artificial induction of olfactory associative memory in Drosophila larvae. In this protocol, the natural reward signal is substituted by thermogenetic activation of octopaminergic neurons in the brain. In parallel, the odor signal is substituted by optogenetic activation of a specific class of olfactory receptor neurons. Association of reward and odor stimuli is achieved with the concomitant application of blue light and heat that leads to activation of both sets of neurons in living transgenic larvae. Given its operational simplicity and robustness, this method could be utilized to further our knowledge on the neurocircuitry mechanism of memory in the fly brain. PMID:27445732

The GABAergic Anterior Paired Lateral Neurons Facilitate Olfactory Reversal Learning in "Drosophila"

ERIC Educational Resources Information Center

Wu, Yanying; Ren, Qingzhong; Li, Hao; Guo, Aike

2012-01-01

Reversal learning has been widely used to probe the implementation of cognitive flexibility in the brain. Previous studies in monkeys identified an essential role of the orbitofrontal cortex (OFC) in reversal learning. However, the underlying circuits and molecular mechanisms are poorly understood. Here, we use the T-maze to investigate the neural…

Experience during Early Adulthood Shapes the Learning Capacities and the Number of Synaptic Boutons in the Mushroom Bodies of Honey Bees ("Apis mellifera")

ERIC Educational Resources Information Center

Cabirol, Amélie; Brooks, Rufus; Groh, Claudia; Barron, Andrew B.; Devaud, Jean-Marc

2017-01-01

The honey bee mushroom bodies (MBs) are brain centers required for specific learning tasks. Here, we show that environmental conditions experienced as young adults affect the maturation of MB neuropil and performance in a MB-dependent learning task. Specifically, olfactory reversal learning was selectively impaired following early exposure to an…

Early social learning triggers neurogenomic expression changes in a swordtail fish.

PubMed

Cui, Rongfeng; Delclos, Pablo J; Schumer, Molly; Rosenthal, Gil G

2017-05-17

Mate choice can play a pivotal role in the nature and extent of reproductive isolation between species. Mating preferences are often dependent on an individual's social experience with adult phenotypes throughout development. We show that olfactory preference in a swordtail fish ( Xiphophorus malinche ) is affected by previous experience with adult olfactory signals. We compare transcriptome-wide gene expression levels of pooled sensory and brain tissues between three treatment groups that differ by social experience: females with no adult exposure, females exposed to conspecifics and females exposed to heterospecifics. We identify potential functionally relevant genes and biological pathways differentially expressed not only between control and exposure groups, but also between groups exposed to conspecifics and heterospecifics. Based on our results, we speculate that vomeronasal receptor type 2 paralogs may detect species-specific pheromone components and thus play an important role in reproductive isolation between species. © 2017 The Author(s).

Olfactory acuity in theropods: palaeobiological and evolutionary implications.

PubMed

Zelenitsky, Darla K; Therrien, François; Kobayashi, Yoshitsugu

2009-02-22

This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds.

Olfactory acuity in theropods: palaeobiological and evolutionary implications

PubMed Central

Zelenitsky, Darla K.; Therrien, François; Kobayashi, Yoshitsugu

2008-01-01

This research presents the first quantitative evaluation of the olfactory acuity in extinct theropod dinosaurs. Olfactory ratios (i.e. the ratio of the greatest diameter of the olfactory bulb to the greatest diameter of the cerebral hemisphere) are analysed in order to infer the olfactory acuity and behavioural traits in theropods, as well as to identify phylogenetic trends in olfaction within Theropoda. A phylogenetically corrected regression of olfactory ratio to body mass reveals that, relative to predicted values, the olfactory bulbs of (i) tyrannosaurids and dromaeosaurids are significantly larger, (ii) ornithomimosaurs and oviraptorids are significantly smaller, and (iii) ceratosaurians, allosauroids, basal tyrannosauroids, troodontids and basal birds are within the 95% CI. Relative to other theropods, olfactory acuity was high in tyrannosaurids and dromaeosaurids and therefore olfaction would have played an important role in their ecology, possibly for activities in low-light conditions, locating food, or for navigation within large home ranges. Olfactory acuity was the lowest in ornithomimosaurs and oviraptorids, suggesting a reduced reliance on olfaction and perhaps an omnivorous diet in these theropods. Phylogenetic trends in olfaction among theropods reveal that olfactory acuity did not decrease in the ancestry of birds, as troodontids, dromaeosaurids and primitive birds possessed typical or high olfactory acuity. Thus, the sense of smell must have remained important in primitive birds and its presumed decrease associated with the increased importance of sight did not occur until later among more derived birds. PMID:18957367

History of smoking and olfaction in Parkinson's disease.

PubMed

Lucassen, Elisabeth B; Sterling, Nicholas W; Lee, Eun-Young; Chen, Honglei; Lewis, Mechelle M; Kong, Lan; Huang, Xuemei

2014-07-01

Olfactory dysfunction is the most common pre-motor symptom in Parkinson's disease (PD), and smoking is known to be associated with lower risk of PD. This study tested the hypothesis that smoking is associated with better olfaction in PD. Smoking history was obtained from 76 PD subjects (22 with a history of smoking [smokers], 54 who never smoked [nonsmokers]), and 70 controls (17 smokers, 53 nonsmokers). Olfaction was assessed using the 40-item University of Pennsylvania Smell Identification Test (UPSIT). The olfactory scores between groups and subgroups were compared using analysis of covariance with adjustment for age, gender, and monoamine oxidase B (MAO-B) inhibitor usage. Overall the olfactory score was lower in PD compared with controls (olfactory scores: 21.5 vs. 33.5, P < 0.0001). Among controls, there was no significant difference in olfaction between smokers and nonsmokers (olfactory scores, 33.2 vs. 34.2; P = 0.95). Among PD subjects, however, smokers scored significantly better regarding olfaction compared with nonsmokers (olfactory scores: 24.4 vs. 19.9, P = 0.02). These data suggest that a history of smoking is associated with better olfaction among PD patients. The finding may be related to why smoking may be protective against PD. Further studies are needed to confirm this finding and investigate the underlying mechanisms. © 2014 International Parkinson and Movement Disorder Society.

Nasal neuron PET imaging quantifies neuron generation and degeneration

PubMed Central

Van de Bittner, Genevieve C.; Riley, Misha M.; Cao, Luxiang; Herrick, Scott P.; Ricq, Emily L.; O’Neill, Michael J.; Ahmed, Zeshan; Murray, Tracey K.; Smith, Jaclyn E.; Wang, Changning; Schroeder, Frederick A.; Albers, Mark W.; Hooker, Jacob M.

2017-01-01

Olfactory dysfunction is broadly associated with neurodevelopmental and neurodegenerative diseases and predicts increased mortality rates in healthy individuals. Conventional measurements of olfactory health assess odor processing pathways within the brain and provide a limited understanding of primary odor detection. Quantification of the olfactory sensory neurons (OSNs), which detect odors within the nasal cavity, would provide insight into the etiology of olfactory dysfunction associated with disease and mortality. Notably, OSNs are continually replenished by adult neurogenesis in mammals, including humans, so OSN measurements are primed to provide specialized insights into neurological disease. Here, we have evaluated a PET radiotracer, [11C]GV1-57, that specifically binds mature OSNs and quantifies the mature OSN population in vivo. [11C]GV1-57 monitored native OSN population dynamics in rodents, detecting OSN generation during postnatal development and aging-associated neurodegeneration. [11C]GV1-57 additionally measured rates of neuron regeneration after acute injury and early-stage OSN deficits in a rodent tauopathy model of neurodegenerative disease. Preliminary assessment in nonhuman primates suggested maintained uptake and saturable binding of [18F]GV1-57 in primate nasal epithelium, supporting its translational potential. Future applications for GV1-57 include monitoring additional diseases or conditions associated with olfactory dysregulation, including cognitive decline, as well as monitoring effects of neuroregenerative or neuroprotective therapeutics. PMID:28112682

Perceptual and Neural Olfactory Similarity in Honeybees

PubMed Central

Sandoz, Jean-Christophe

2005-01-01

The question of whether or not neural activity patterns recorded in the olfactory centres of the brain correspond to olfactory perceptual measures remains unanswered. To address this question, we studied olfaction in honeybees Apis mellifera using the olfactory conditioning of the proboscis extension response. We conditioned bees to odours and tested generalisation responses to different odours. Sixteen odours were used, which varied both in their functional group (primary and secondary alcohols, aldehydes and ketones) and in their carbon-chain length (from six to nine carbons).The results obtained by presentation of a total of 16 × 16 odour pairs show that (i) all odorants presented could be learned, although acquisition was lower for short-chain ketones; (ii) generalisation varied depending both on the functional group and the carbon-chain length of odours trained; higher generalisation was found between long-chain than between short-chain molecules and between groups such as primary and secondary alcohols; (iii) for some odour pairs, cross-generalisation between odorants was asymmetric; (iv) a putative olfactory space could be defined for the honeybee with functional group and carbon-chain length as inner dimensions; (v) perceptual distances in such a space correlate well with physiological distances determined from optophysiological recordings of antennal lobe activity. We conclude that functional group and carbon-chain length are inner dimensions of the honeybee olfactory space and that neural activity in the antennal lobe reflects the perceptual quality of odours. PMID:15736975

Dietary intakes of fats, fish and nuts and olfactory impairment in older adults.

PubMed

Gopinath, Bamini; Sue, Carolyn M; Flood, Victoria M; Burlutsky, George; Mitchell, Paul

2015-07-01

It is unclear whether lifestyle modifications, such as dietary changes, should be advocated to prevent olfactory dysfunction. We investigated the association between dietary intakes of fats (saturated, mono-unsaturated and polyunsaturated fats, and cholesterol) and related food groups (nuts, fish, butter, margarine) with olfactory impairment. There were 1331 and 667 participants (older than 60 years) at baseline and 5-year follow-up, respectively, with complete olfaction and dietary data. Dietary data were collected using a validated semi-quantitative FFQ. Olfaction was measured using the San Diego Odor Identification Test. In a cross-sectional analysis of baseline data, those in the highest v. lowest quartile of n-6 PUFA intake had reduced odds of having any olfactory impairment, multivariable-adjusted OR 0.66 (95% CI 0.44, 0.97), P for trend = 0.06. Participants in the highest v. lowest quartile of margarine consumption had a 65% reduced odds of having moderate/severe olfactory impairment (P for trend = 0.02). Participants in the highest quartile compared to the lowest quartile (reference) of nut consumption had a 46% (P for trend = 0.01) and 58% (P for trend = 0.001) reduced odds of having any or mild olfactory impairment, respectively. Older adults in the highest v. lowest quartile of fish consumption had 35% (P for trend = 0.03) and 50% (P for trend = 0.01) reduced likelihood of having any or mild olfactory impairment, respectively. In longitudinal analyses, a marginally significant association was observed between nut consumption and incidence of any olfactory impairment, highest v. lowest quartile of nut consumption: OR 0.61 (95% CI 0.37, 1.00). Older adults with the highest consumption of nuts and fish had reduced odds of olfactory impairment, independent of potential confounding variables.

Sadness might isolate you in a non-smelling world: olfactory perception and depression

PubMed Central

Schablitzky, Sylvia; Pause, Bettina M.

2014-01-01

Major depressive disorder (MDD) occurs with a high prevalence among mental illnesses. MDD patients experience sadness and hopelessness, with blunted affective reactivity. However, such depressive episodes are also key symptoms in other depressive disorders, like Bipolar Disorder (BPD) or Seasonal Affective Disorder (SAD). Moreover, depressive symptoms can also be found in healthy individuals, but are experienced as less severe or for a shorter duration than in patients. Here, it is aimed to summarize studies investigating odor perception in depression, including depressive states in healthy individuals and patient populations. Odor perception in depression has been assessed with psychophysical methods (olfactory sensitivity, odor identification, and discrimination), and odor ratings (intensity, emotional valence, familiarity). In addition, some studies investigated affective reactions to odors, and physiological and anatomical correlates of odor perception in depression. The summary reveals that MDD is associated with reduced olfactory sensitivity. However, odor identification and discrimination scores seem to be unaffected by depression. The reduced olfactory sensitivity might be associated with a reduced ability to encode olfactory information and a reduced volume of the olfactory bulb. While similar processes seem to occur in healthy individuals experiencing depressive states, they have not been observed in BPD or SAD patients. However, in order to conclude that the reduced olfactory sensitivity is directly linked to depression, it is suggested that studies should implement control measures of cognitive performances or perceptual abilities in other stimulus modalities. It is concluded that the reduced olfactory performance in MDD patients seems to be disorder-, modality-, and test-specific, and that the application of an appropriate olfactory and cognitive test-battery might be highly useful in the differential diagnosis of MDD. PMID:24570666

Odor information transfer in the stingless bee Melipona quadrifasciata: effect of in-hive experiences on classical conditioning of proboscis extension.

PubMed

Mc Cabe, Sofía I; Farina, Walter M

2009-02-01

A recent study showed that the stingless bee Melipona quadrifasciata could learn to discriminate odors in a classical conditioning of proboscis extension response (PER). Here we used this protocol to investigate the ability of these bees to use olfactory information obtained within the colony in an experimental context: the PER paradigm. We compared their success in solving a classical differential conditioning depending on the previous olfactory experiences received inside the nest. We found that M. quadrifasciata bees are capable of transferring the food-odor information acquired in the colony to a differential conditioning in the PER paradigm. Bees attained higher discrimination levels when they had previously encountered the rewarded odor associated to food inside the hive. The increase in the discrimination levels, however, was in some cases unspecific to the odor used indicating a certain degree of generalization. The influence of the food scent offered at a field feeder 24 h before the classical conditioning could also be seen in the discrimination attained by the foragers in the PER setup, detecting the presence of long-term memory. Moreover, the improved performance of recruited bees in the PER paradigm suggests the occurrence of social learning of nectar scents inside the stingless bees' hives.

Encoding of Olfactory Information with Oscillating Neural Assemblies

NASA Astrophysics Data System (ADS)

Laurent, Gilles; Davidowitz, Hananel

1994-09-01

In the brain, fast oscillations of local field potentials, which are thought to arise from the coherent and rhythmic activity of large numbers of neurons, were observed first in the olfactory system and have since been described in many neocortical areas. The importance of these oscillations in information coding, however, is controversial. Here, local field potential and intracellular recordings were obtained from the antennal lobe and mushroom body of the locust Schistocerca americana. Different odors evoked coherent oscillations in different, but usually overlapping, ensembles of neurons. The phase of firing of individual neurons relative to the population was not dependent on the odor. The components of a coherently oscillating ensemble of neurons changed over the duration of a single exposure to an odor. It is thus proposed that odors are encoded by specific but dynamic assemblies of coherently oscillating neurons. Such distributed and temporal representation of complex sensory signals may facilitate combinatorial coding and associative learning in these, and possibly other, sensory networks.

Reward Systems in the Brain and Nutrition.

PubMed

Rolls, Edmund T

2016-07-17

The taste cortex in the anterior insula provides separate and combined representations of the taste, temperature, and texture of food in the mouth independently of hunger and thus of reward value and pleasantness. One synapse on, in the orbitofrontal cortex, these sensory inputs are combined by associative learning with olfactory and visual inputs for some neurons, and these neurons encode food reward value in that they respond to food only when hunger is present and in that activations correlate linearly with subjective pleasantness. Cognitive factors, including word-level descriptions and selective attention to affective value, modulate the representation of the reward value of taste, olfactory, and flavor stimuli in the orbitofrontal cortex and a region to which it projects, the anterior cingulate cortex. These food reward representations are important in the control of appetite and food intake. Individual differences in reward representations may contribute to obesity, and there are age-related differences in these reward representations. Implications of how reward systems in the brain operate for understanding, preventing, and treating obesity are described.

Gray matter alteration in isolated congenital anosmia patient: a voxel-based morphometry study.

PubMed

Yao, Linyin; Yi, Xiaoli; Wei, Yongxiang

2013-09-01

Decreased volume of gray matter (GM) was observed in olfactory loss in patients with neurodegenerative disorder. However, GM volume has not yet been investigated in isolated congenital anosmia (ICA) people. We herewith investigated the volume change of gray matter of an ICA boy by morphometric analysis of magnetic resonance images (voxel-based morphometry), and compared with that of 20 age-matched healthy controls. ICA boy presented a significant decrease in GM volume in the orbitofrontal cortex, anterior cingulate cortex, middle cingulate cortex, thalamus, insular cortex, cerebellum, precuneus, gyrus rectus, subcallosal gyrus, middle temporal gyrus, fusiform gyrus and piriform cortex. No significant GM volume increase was detected in other brain areas. The pattern of GM atrophy was similar as previous literature reported. Our results identified similar GM volume alterations regardless of the causes of olfactory impairment. Decreased GM volume was not only shown in olfactory bulbs, olfactory tracts and olfactory sulcus, also in primary olfactory cortex and the secondary cerebral olfactory areas in ICA people. This is the first study to evaluate GM volume alterations in ICA people.

Odor Preference Learning and Memory Modify GluA1 Phosphorylation and GluA1 Distribution in the Neonate Rat Olfactory Bulb: Testing the AMPA Receptor Hypothesis in an Appetitive Learning Model

ERIC Educational Resources Information Center

Cui, Wen; Darby-King, Andrea; Grimes, Matthew T.; Howland, John G.; Wang, Yu Tian; McLean, John H.; Harley, Carolyn W.

2011-01-01

An increase in synaptic AMPA receptors is hypothesized to mediate learning and memory. AMPA receptor increases have been reported in aversive learning models, although it is not clear if they are seen with memory maintenance. Here we examine AMPA receptor changes in a cAMP/PKA/CREB-dependent appetitive learning model: odor preference learning in…

Calmodulin permanently associates with rat olfactory CNG channels under native conditions.

PubMed

Bradley, Jonathan; Bönigk, Wolfgang; Yau, King-Wai; Frings, Stephan

2004-07-01

An important mechanism by which vertebrate olfactory sensory neurons rapidly adapt to odorants is feedback modulation of the Ca(2+)-permeable cyclic nucleotide-gated (CNG) transduction channels. Extensive heterologous studies of homomeric CNGA2 channels have led to a molecular model of channel modulation based on the binding of calcium-calmodulin to a site on the cytoplasmic amino terminus of CNGA2. Native rat olfactory CNG channels, however, are heteromeric complexes of three homologous but distinct subunits. Notably, in heteromeric channels, we found no role for CNGA2 in feedback modulation. Instead, an IQ-type calmodulin-binding site on CNGB1b and a similar but previously unidentified site on CNGA4 are necessary and sufficient. These sites seem to confer binding of Ca(2+)-free calmodulin (apocalmodulin), which is then poised to trigger inhibition of native channels in the presence of Ca(2+).

Plasticity in the olfactory bulb of the maternal mouse is prevented by gestational stress

PubMed Central

Belnoue, Laure; Malvaut, Sarah; Ladevèze, Elodie; Abrous, Djoher Nora; Koehl, Muriel

2016-01-01

Maternal stress is associated with an altered mother-infant relationship that endangers offspring development, leading to emotional/behavioral problems. However, little research has investigated the stress-induced alterations of the maternal brain that could underlie such a disruption of mother-infant bonding. Olfactory cues play an extensive role in the coordination of mother-infant interactions, suggesting that motherhood may be associated to enhanced olfactory performances, and that this effect may be abolished by maternal stress. To test this hypothesis, we analyzed the impact of motherhood under normal conditions or after gestational stress on olfactory functions in C57BL/6 J mice. We report that gestational stress alters maternal behavior and prevents both mothers’ ability to discriminate pup odors and motherhood-induced enhancement in odor memory. We investigated adult bulbar neurogenesis as a potential mechanism of the enhanced olfactory function in mothers and found that motherhood was associated with an increased complexity of the dendritic tree of newborn neurons. This motherhood-evoked remodeling was totally prevented by gestational stress. Altogether, our results may thus provide insight into the neural changes that could contribute to altered maternal behavior in stressed mothers. PMID:27886228

Evaluation of olfactory and auditory system effects of the antihyperthyroid drug carbimazole in the Long-Evans rat.

PubMed

Genter, M B

1998-01-01

Carbimazole (2-carbethoxythio-1-methylimidazole) is a thiocarbamide drug used in the treatment of hyperthyroidism in humans. Side effects associated with carbimazole treatment are reported to include impaired taste, impaired olfaction, and hearing loss. The structurally similar antihyperthyroid drug methimazole (1-methyl-2-mercaptoimidazole), also reportedly associated with impaired taste and olfaction in humans, has recently been demonstrated by this laboratory to be an olfactory toxicant by both the oral and intraperitoneal routes of exposure in rodents. A systematic evaluation of sensory system effects of these compounds, either in rodents or humans, is not available in the literature. Male Long-Evans rats were used to evaluate the auditory and olfactory toxicity of carbimazole by two routes of exposure. Histopathological evaluation of nasal cavities from rats administered carbimazole via i.p. and oral routes revealed olfactory mucosal damage and early evidence of repair; a no-observed effect level (NOEL) of 100 mg/kg was observed for orally administered carbimazole. Further, these studies demonstrate evidence for the generation of the olfactory toxic metabolites of carbimazole by the olfactory mucosa itself, as incubation of carbimazole with an olfactory S9 preparation resulted in NADPH-dependent degradation of carbimazole. Evaluation of the auditory startle response in carbimazole-treated rats revealed no deficits, demonstrating that carbimazole does not cause a global loss of hearing in rats.

Appetitive but Not Aversive Olfactory Conditioning Modifies Antennal Movements in Honeybees

ERIC Educational Resources Information Center

Cholé, Hanna; Junca, Pierre; Sandoz, Jean-Christophe

2015-01-01

In honeybees, two olfactory conditioning protocols allow the study of appetitive and aversive Pavlovian associations. Appetitive conditioning of the proboscis extension response (PER) involves associating an odor, the conditioned stimulus (CS) with a sucrose solution, the unconditioned stimulus (US). Conversely, aversive conditioning of the sting…

Extrabulbar olfactory system and nervus terminalis FMRFamide immunoreactive components in Xenopus laevis ontogenesis.

PubMed

Pinelli, Claudia; D'Aniello, Biagio; Polese, Gianluca; Rastogi, Rakesh K

2004-09-01

The extrabulbar olfactory system (EBOS) is a collection of nerve fibers which originate from primary olfactory receptor-like neurons and penetrate into the brain bypassing the olfactory bulbs. Our description is based upon the application of two neuronal tracers (biocytin, carbocyanine DiI) in the olfactory sac, at the cut end of the olfactory nerve and in the telencephalon of the developing clawed frog. The extrabulbar olfactory system was observed already at stage 45, which is the first developmental stage compatible with our techniques; at this stage, the extrabulbar olfactory system fibers terminated diffusely in the preoptic area. A little later in development, i.e. at stage 50, the extrabulbar olfactory system was maximally developed, extending as far caudally as the rhombencephalon. In the metamorphosing specimens, the extrabulbar olfactory system appeared reduced in extension; caudally, the fiber terminals did not extend beyond the diencephalon. While a substantial overlapping of biocytin/FMRFamide immunoreactivity was observed along the olfactory pathways as well as in the telencephalon, FMRFamide immunoreactivity was never observed to be colocalized in the same cellular or fiber components visualized by tracer molecules. The question whether the extrabulbar olfactory system and the nervus terminalis (NT) are separate anatomical entities or represent an integrated system is discussed.

An information theoretic model of information processing in the Drosophila olfactory system: the role of inhibitory neurons for system efficiency.

PubMed

Faghihi, Faramarz; Kolodziejski, Christoph; Fiala, André; Wörgötter, Florentin; Tetzlaff, Christian

2013-12-20

Fruit flies (Drosophila melanogaster) rely on their olfactory system to process environmental information. This information has to be transmitted without system-relevant loss by the olfactory system to deeper brain areas for learning. Here we study the role of several parameters of the fly's olfactory system and the environment and how they influence olfactory information transmission. We have designed an abstract model of the antennal lobe, the mushroom body and the inhibitory circuitry. Mutual information between the olfactory environment, simulated in terms of different odor concentrations, and a sub-population of intrinsic mushroom body neurons (Kenyon cells) was calculated to quantify the efficiency of information transmission. With this method we study, on the one hand, the effect of different connectivity rates between olfactory projection neurons and firing thresholds of Kenyon cells. On the other hand, we analyze the influence of inhibition on mutual information between environment and mushroom body. Our simulations show an expected linear relation between the connectivity rate between the antennal lobe and the mushroom body and firing threshold of the Kenyon cells to obtain maximum mutual information for both low and high odor concentrations. However, contradicting all-day experiences, high odor concentrations cause a drastic, and unrealistic, decrease in mutual information for all connectivity rates compared to low concentration. But when inhibition on the mushroom body is included, mutual information remains at high levels independent of other system parameters. This finding points to a pivotal role of inhibition in fly information processing without which the system efficiency will be substantially reduced.

Risk factors for hazardous events in olfactory-impaired patients.

PubMed

Pence, Taylor S; Reiter, Evan R; DiNardo, Laurence J; Costanzo, Richard M

2014-10-01

Normal olfaction provides essential cues to allow early detection and avoidance of potentially hazardous situations. Thus, patients with impaired olfaction may be at increased risk of experiencing certain hazardous events such as cooking or house fires, delayed detection of gas leaks, and exposure to or ingestion of toxic substances. To identify risk factors and potential trends over time in olfactory-related hazardous events in patients with impaired olfactory function. Retrospective cohort study of 1047 patients presenting to a university smell and taste clinic between 1983 and 2013. A total of 704 patients had both clinical olfactory testing and a hazard interview and were studied. On the basis of olfactory function testing results, patients were categorized as normosmic (n = 161), mildly hyposmic (n = 99), moderately hyposmic (n = 93), severely hyposmic (n = 142), and anosmic (n = 209). Patient evaluation including interview, examination, and olfactory testing. Incidence of specific olfaction-related hazardous events (ie, burning pots and/or pans, starting a fire while cooking, inability to detect gas leaks, inability to detect smoke, and ingestion of toxic substances or spoiled foods) by degree of olfactory impairment. The incidence of having experienced any hazardous event progressively increased with degree of impairment: normosmic (18.0%), mildly hyposmic (22.2%), moderately hyposmic (31.2%), severely hyposmic (32.4%), and anosmic (39.2%). Over 3 decades there was no significant change in the overall incidence of hazardous events. Analysis of demographic data (age, sex, race, smoking status, and etiology) revealed significant differences in the incidence of hazardous events based on age (among 397 patients <65 years, 148 [37.3%] with hazardous event, vs 31 of 146 patients ≥65 years [21.3%]; P < .001), sex (among 278 women, 106 [38.1%] with hazardous event, vs 73 of 265 men [27.6%]; P = .009), and race (among 98 African Americans, 41 [41.8%] with hazardous event, vs 134 of 434 whites [30.9%]; P = .04). Increased level of olfactory impairment portends an increased risk of experiencing a hazardous event. Risk is further impacted by individuals' age, sex, and race. These results may assist health care practitioners in counseling patients on the risks associated with olfactory impairment.

Evolution of olfactory receptors.

PubMed

Hoover, Kara C

2013-01-01

Olfactory receptors are a specialized set of receptor cells responsible for the detection of odors. These cells are G protein-coupled receptors and expressed in the cell membranes of olfactory sensory neurons. Once a cell is activated by a ligand, it initiates a signal transduction cascade that produces a nerve impulse to the brain where odor perception is processed. Vertebrate olfactory evolution is characterized by birth-and-death events, a special case of the stochastic continuous time Markov process. Vertebrate fish have three general types of receptor cells (two dedicated to pheromones). Terrestrial animals have different epithelial biology due to the specialized adaptation to detecting airborne odors. Two general classes of olfactory receptor gene reflect the vertebrate marine heritage (Class I) and the derived amphibian, reptile, and mammal terrestrial heritage (Class II). While we know much about olfactory receptor cells, there are still areas where our knowledge is insufficient, such as intra-individual diversity throughout the life time, epigenetic processes acting on olfactory receptors, and association of ligands to specific cells.

A Tyrosine-Hydroxylase Characterization of Dopaminergic Neurons in the Honey Bee Brain

PubMed Central

Tedjakumala, Stevanus R.; Rouquette, Jacques; Boizeau, Marie-Laure; Mesce, Karen A.; Hotier, Lucie; Massou, Isabelle; Giurfa, Martin

2017-01-01

Dopamine (DA) plays a fundamental role in insect behavior as it acts both as a general modulator of behavior and as a value system in associative learning where it mediates the reinforcing properties of unconditioned stimuli (US). Here we aimed at characterizing the dopaminergic neurons in the central nervous system of the honey bee, an insect that serves as an established model for the study of learning and memory. We used tyrosine hydroxylase (TH) immunoreactivity (ir) to ensure that the neurons detected synthesize DA endogenously. We found three main dopaminergic clusters, C1–C3, which had been previously described; the C1 cluster is located in a small region adjacent to the esophagus (ES) and the antennal lobe (AL); the C2 cluster is situated above the C1 cluster, between the AL and the vertical lobe (VL) of the mushroom body (MB); the C3 cluster is located below the calyces (CA) of the MB. In addition, we found a novel dopaminergic cluster, C4, located above the dorsomedial border of the lobula, which innervates the visual neuropils of the bee brain. Additional smaller processes and clusters were found and are described. The profuse dopaminergic innervation of the entire bee brain and the specific connectivity of DA neurons, with visual, olfactory and gustatory circuits, provide a foundation for a deeper understanding of how these sensory modules are modulated by DA, and the DA-dependent value-based associations that occur during associative learning. PMID:28740466

Conditioning Individual Mosquitoes to an Odor: Sex, Source, and Time

PubMed Central

Sanford, Michelle R.; Tomberlin, Jeffery K.

2011-01-01

Olfactory conditioning of mosquitoes may have important implications for vector-pathogen-host dynamics. If mosquitoes learn about specific host attributes associated with pathogen infection, it may help to explain the heterogeneity of biting and disease patterns observed in the field. Sugar-feeding is a requirement for survival in both male and female mosquitoes. It provides a starting point for learning research in mosquitoes that avoids the confounding factors associated with the observer being a potential blood-host and has the capability to address certain areas of close-range mosquito learning behavior that have not previously been described. This study was designed to investigate the ability of the southern house mosquito, Culex quinquefasciatus Say to associate odor with a sugar-meal with emphasis on important experimental considerations of mosquito age (1.2 d old and 3–5 d old), sex (male and female), source (laboratory and wild), and the time between conditioning and testing (<5 min, 1 hr, 2.5 hr, 5 hr, 10 hr, and 24 hr). Mosquitoes were individually conditioned to an odor across these different experimental conditions. Details of the conditioning protocol are presented as well as the use of binary logistic regression to analyze the complex dataset generated from this experimental design. The results suggest that each of the experimental factors may be important in different ways. Both the source of the mosquitoes and sex of the mosquitoes had significant effects on conditioned responses. The largest effect on conditioning was observed in the lack of positive response following conditioning for females aged 3–5 d derived from a long established colony. Overall, this study provides a method for conditioning experiments involving individual mosquitoes at close range and provides for future discussion of the relevance and broader questions that can be asked of olfactory conditioning in mosquitoes. PMID:21887384

Persistent ERK Activation Maintains Learning-Induced Long-Lasting Modulation of Synaptic Connectivity

ERIC Educational Resources Information Center

Cohen-Matsliah, Sivan Ida; Seroussi, Yaron; Rosenblum, Kobi; Barkai, Edi

2008-01-01

Pyramidal neurons in the piriform cortex from olfactory-discrimination (OD) trained rats undergo synaptic modifications that last for days after learning. A particularly intriguing modification is reduced paired-pulse facilitation (PPF) in the synapses interconnecting these cells; a phenomenon thought to reflect enhanced synaptic release. The…

CaMKII knockdown affects both early and late phases of olfactory long-term memory in the honeybee.

PubMed

Scholl, Christina; Kübert, Natalie; Muenz, Thomas S; Rössler, Wolfgang

2015-12-01

Honeybees are able to solve complex learning tasks and memorize learned information for long time periods. The molecular mechanisms mediating long-term memory (LTM) in the honeybee Apis mellifera are, to a large part, still unknown. We approached this question by investigating the potential function of the calcium/calmodulin-dependent protein kinase II (CaMKII), an enzyme known as a 'molecular memory switch' in vertebrates. CaMKII is able to switch to a calcium-independent constitutively active state, providing a mechanism for a molecular memory and has further been shown to play an essential role in structural synaptic plasticity. Using a combination of knockdown by RNA interference and pharmacological manipulation, we disrupted the function of CaMKII during olfactory learning and memory formation. We found that learning, memory acquisition and mid-term memory were not affected, but all manipulations consistently resulted in an impaired LTM. Both early LTM (24 h after learning) and late LTM (72 h after learning) were significantly disrupted, indicating the necessity of CaMKII in two successive stages of LTM formation in the honeybee. © 2015. Published by The Company of Biologists Ltd.

Insulin effects on honeybee appetitive behaviour.

PubMed

Mengoni Goñalons, Carolina; Guiraud, Marie; de Brito Sanchez, María Gabriela; Farina, Walter M

2016-10-01

Worker honeybees (Apis mellifera) carry out multiple tasks throughout their adult lifespan. It has been suggested that the insulin/insulin-like signalling pathway participates in regulating behavioural maturation in eusocial insects. Insulin signalling increases as the honeybee worker transitions from nurse to food processor to forager. As behavioural shifts require differential usage of sensory modalities, our aim was to assess insulin effects on olfactory and gustatory responsiveness as well as on olfactory learning in preforaging honeybee workers of different ages. Adults were reared in the laboratory or in the hive. Immediately after being injected with insulin or vehicle (control), and focusing on the proboscis extension response, bees were tested for their spontaneous response to odours, sucrose responsiveness and ability to discriminate odours through olfactory conditioning. Bees injected with insulin have higher spontaneous odour responses. Sucrose responsiveness and odour discrimination are differentially affected by treatment according to age: whereas insulin increases gustatory responsiveness and diminishes learning abilities of younger workers, it has the opposite effect on older bees. In summary, insulin can improve chemosensory responsiveness in young workers, but also worsens their learning abilities to discriminate odours. The insulin signalling pathway is responsive in young workers, although they are not yet initiating outdoor activities. Our results show strong age-dependent effects of insulin on appetitive behaviour, which uncover differences in insulin signalling regulation throughout the honeybee worker's adulthood. © 2016. Published by The Company of Biologists Ltd.

Improved spatial accuracy of functional maps in the rat olfactory bulb using supervised machine learning approach.

PubMed

Murphy, Matthew C; Poplawsky, Alexander J; Vazquez, Alberto L; Chan, Kevin C; Kim, Seong-Gi; Fukuda, Mitsuhiro

2016-08-15

Functional MRI (fMRI) is a popular and important tool for noninvasive mapping of neural activity. As fMRI measures the hemodynamic response, the resulting activation maps do not perfectly reflect the underlying neural activity. The purpose of this work was to design a data-driven model to improve the spatial accuracy of fMRI maps in the rat olfactory bulb. This system is an ideal choice for this investigation since the bulb circuit is well characterized, allowing for an accurate definition of activity patterns in order to train the model. We generated models for both cerebral blood volume weighted (CBVw) and blood oxygen level dependent (BOLD) fMRI data. The results indicate that the spatial accuracy of the activation maps is either significantly improved or at worst not significantly different when using the learned models compared to a conventional general linear model approach, particularly for BOLD images and activity patterns involving deep layers of the bulb. Furthermore, the activation maps computed by CBVw and BOLD data show increased agreement when using the learned models, lending more confidence to their accuracy. The models presented here could have an immediate impact on studies of the olfactory bulb, but perhaps more importantly, demonstrate the potential for similar flexible, data-driven models to improve the quality of activation maps calculated using fMRI data. Copyright © 2016 Elsevier Inc. All rights reserved.

Levels-of-processing effects on a task of olfactory naming.

PubMed

Royet, Jean-Pierre; Koenig, Olivier; Paugam-Moisy, Helene; Puzenat, Didier; Chasse, Jean-Luc

2004-02-01

The effects of odor processing were investigated at various analytical levels, from simple sensory analysis to deep or semantic analysis, on a subsequent task of odor naming. Students (106 women, 23.6 +/- 5.5 yr. old; 65 men, 25.1 +/- 7.1 yr. old) were tested. The experimental procedure included two successive sessions, a first session to characterize a set of 30 odors with criteria that used various depths of processing and a second session to name the odors as quickly as possible. Four processing conditions rated the odors using descriptors before naming the odor. The control condition did not rate the odors before naming. The processing conditions were based on lower-level olfactory judgments (superficial processing), higher-level olfactory-gustatory-somesthetic judgments (deep processing), and higher-level nonolfactory judgments (Deep-Control processing, with subjects rating odors with auditory and visual descriptors). One experimental condition successively grouped lower- and higher-level olfactory judgments (Superficial-Deep processing). A naming index which depended on response accuracy and the subjects' response time were calculated. Odor naming was modified for 18 out of 30 odorants as a function of the level of processing required. For 94.5% of significant variations, the scores for odor naming were higher following those tasks for which it was hypothesized that the necessary olfactory processing was carried out at a deeper level. Performance in the naming task was progressively improved as follows: no rating of odors, then superficial, deep-control, deep, and superficial-deep processings. These data show that the deepest olfactory encoding was later associated with progressively higher performance in naming.

Circadian modulation of short-term memory in Drosophila.

PubMed

Lyons, Lisa C; Roman, Gregg

2009-01-01

Endogenous biological clocks are widespread regulators of behavior and physiology, allowing for a more efficient allocation of efforts and resources over the course of a day. The extent that different processes are regulated by circadian oscillators, however, is not fully understood. We investigated the role of the circadian clock on short-term associative memory formation using a negatively reinforced olfactory-learning paradigm in Drosophila melanogaster. We found that memory formation was regulated in a circadian manner. The peak performance in short-term memory (STM) occurred during the early subjective night with a twofold performance amplitude after a single pairing of conditioned and unconditioned stimuli. This rhythm in memory is eliminated in both timeless and period mutants and is absent during constant light conditions. Circadian gating of sensory perception does not appear to underlie the rhythm in short-term memory as evidenced by the nonrhythmic shock avoidance and olfactory avoidance behaviors. Moreover, central brain oscillators appear to be responsible for the modulation as cryptochrome mutants, in which the antennal circadian oscillators are nonfunctional, demonstrate robust circadian rhythms in short-term memory. Together these data suggest that central, rather than peripheral, circadian oscillators modulate the formation of short-term associative memory and not the perception of the stimuli.

Lesion of the Olfactory Epithelium Accelerates Prion Neuroinvasion and Disease Onset when Prion Replication Is Restricted to Neurons

PubMed Central

Crowell, Jenna; Wiley, James A.; Bessen, Richard A.

2015-01-01

Natural prion diseases of ruminants are moderately contagious and while the gastrointestinal tract is the primary site of prion agent entry, other mucosae may be entry sites in a subset of infections. In the current study we examined prion neuroinvasion and disease induction following disruption of the olfactory epithelium in the nasal mucosa since this site contains environmentally exposed olfactory sensory neurons that project directly into the central nervous system. Here we provide evidence for accelerated prion neuroinvasion and clinical onset from the olfactory mucosa after disruption and regeneration of the olfactory epithelium and when prion replication is restricted to neurons. In transgenic mice with neuron restricted replication of prions, there was a reduction in survival when the olfactory epithelium was disrupted prior to intranasal inoculation and there was >25% decrease in the prion incubation period. In a second model, the neurotropic DY strain of transmissible mink encephalopathy was not pathogenic in hamsters by the nasal route, but 50% of animals exhibited brain infection and/or disease when the olfactory epithelium was disrupted prior to intranasal inoculation. A time course analysis of prion deposition in the brain following loss of the olfactory epithelium in models of neuron-restricted prion replication suggests that neuroinvasion from the olfactory mucosa is via the olfactory nerve or brain stem associated cranial nerves. We propose that induction of neurogenesis after damage to the olfactory epithelium can lead to prion infection of immature olfactory sensory neurons and accelerate prion spread to the brain. PMID:25822718

Measurement and Analysis of Olfactory Responses with the Aim of Establishing an Objective Diagnostic Method for Central Olfactory Disorders

NASA Astrophysics Data System (ADS)

Uno, Tominori; Wang, Li-Qun; Miwakeichi, Fumikazu; Tonoike, Mitsuo; Kaneda, Teruo

In order to establish a new diagnostic method for central olfactory disorders and to identify objective indicators, we measured and analyzed brain activities in the parahippocampal gyrus and uncus, region of responsibility for central olfactory disorders. The relationship between olfactory stimulation and brain response at region of responsibility can be examined in terms of fitted responses (FR). FR in these regions may be individual indicators of changes in brain olfactory responses. In the present study, in order to non-invasively and objectively measure olfactory responses, an odor oddball task was conducted on four healthy volunteers using functional magnetic resonance imaging (fMRI) and a odorant stimulator with blast-method. The results showed favorable FR and activation in the parahippocampal gyrus or uncus in all subjects. In some subjects, both the parahippocampal gyrus and uncus were activated. Furthermore, activation was also confirmed in the cingulate gyrus, middle frontal gyrus, precentral gyrus, postcentral gyrus, superior temporal gyrus and insula. The hippocampus and uncus are known to be involved in the olfactory disorders associated with early-stage Alzheimer's disease and other olfactory disorders. In the future, it will be necessary to further develop the present measurement and analysis method to clarify the relationship between central olfactory disorders and brain activities and establish objective indicators that are useful for diagnosis.

Cilia- and Flagella-Associated Protein 69 Regulates Olfactory Transduction Kinetics in Mice

PubMed Central

Dong, Frederick N.

2017-01-01

Animals detect odorous chemicals through specialized olfactory sensory neurons (OSNs) that transduce odorants into neural electrical signals. We identified a novel and evolutionarily conserved protein, cilia- and flagella-associated protein 69 (CFAP69), in mice that regulates olfactory transduction kinetics. In the olfactory epithelium, CFAP69 is enriched in OSN cilia, where olfactory transduction occurs. Bioinformatic analysis suggests that a large portion of CFAP69 can form Armadillo-type α-helical repeats, which may mediate protein–protein interactions. OSNs lacking CFAP69, remarkably, displayed faster kinetics in both the on and off phases of electrophysiological responses at both the neuronal ensemble level as observed by electroolfactogram and the single-cell level as observed by single-cell suction pipette recordings. In single-cell analysis, OSNs lacking CFAP69 showed faster response integration and were able to fire APs more faithfully to repeated odor stimuli. Furthermore, both male and female mutant mice that specifically lack CFAP69 in OSNs exhibited attenuated performance in a buried food pellet test when a background of the same odor to the food pellet was present even though they should have better temporal resolution of coding olfactory stimulation at the peripheral. Therefore, the role of CFAP69 in the olfactory system seems to be to allow the olfactory transduction machinery to work at a precisely regulated range of response kinetics for robust olfactory behavior. SIGNIFICANCE STATEMENT Sensory receptor cells are generally thought to evolve to respond to sensory cues as fast as they can. This idea is consistent with mutational analyses in various sensory systems, where mutations of sensory receptor cells often resulted in reduced response size and slowed response kinetics. Contrary to this idea, we have found that there is a kinetic “damper” present in the olfactory transduction cascade of the mouse that slows down the response kinetics and, by doing so, it reduces the peripheral temporal resolution in coding odor stimuli and allows for robust olfactory behavior. This study should trigger a rethinking of the significance of the intrinsic speed of sensory transduction and the pattern of the peripheral coding of sensory stimuli. PMID:28495971

Ultrastructural characterisation of the olfactory mucosa of the armadillo Dasypus hybridus (Dasypodidae, Xenarthra)

PubMed Central

FERRARI, C. C.; CARMANCHAHI, P. D.; ALDANA MARCOS, H. J.; AFFANNI, J. M.

2000-01-01

The ultrastructure of the olfactory mucosa of the armadillo Dasypus hybridus was studied. A comparison with the olfactory mucosa of another armadillo (Chaetophractus villosus) was made. The olfactory mucosa of D. hybridus shows many features which are similar to those of other mammals. Interestingly, it differs from the olfactory mucosa of the armadillo C. villosus. A suggestion is made that these differences may be due to differences in the digging habits of these species. In Dasypus, the supporting cells (SCs) showed dense vacuoles, multivesicular bodies and lysosome-like bodies probably related with the endocytotic system. The SCs show a dense network of SER presumably associated with xenobiotic mechanisms. The olfactory receptor neurons exhibit lysosome-like bodies and multivesicular bodies in their perikarya. These organelles suggest the presence of an endocytotic system. Duct cells of Bowman's glands exhibit secretory activities. Bowman's glands are compound-branched tubulo-acinar mixed glands with merocrine secretory mechanisms. PMID:10739023

[Clinical and MRI Findings in Patients with Congenital Anosmia].

PubMed

Ogawa, Takao; Kato, Tomohisa; Ono, Mayu; Shimizu, Takeshi

2015-08-01

The clinical characteristics of 16 patients with congenital anosmia were examined retrospectively. MRI (magnetic resonance imaging) was used to assess the morphological changes in the olfactory bulbs and olfactory sulci according to the method of P. Rombaux (2009). Congenital anosmia was divided into two forms: syndromic forms in association with a syndrome, and isolated forms without evidence of other defects. Only three patients (19%) in our series had syndromic forms of congenital anosmia, such as the Kallmann syndrome. Most cases (13 patients, 81%) had isolated congenital anosmia. Psychophysical testing of the olfactory function included T&T olfactometry and the intravenous Alinamin test, which are widely used in Japan. In T&T olfactometry, detection and recognition thresholds for the five odorants are used to assign a diagnostic category representing the level of olfactory function. Most cases (14 patients, 88%) showed off-scale results on T&T olfactometry, and the Alinamin test resulted in no response in all 11 patients who underwent the test. Abnormal MRI findings of the olfactory bulbs and sulci were detected in 15 of 16 patients (94%). Olfactory bulbs were bilaterally absent in nine patients (56%), and two patients (13%) had unilateral olfactory bulbs. Four patients (25%) had bilateral hypoplastic olfactory bulbs, and only one patient had normal olfactory bulbs (6%). The olfactory sulcus was unilaterally absent in one patient (6%), and nine patients (56%) had bilaterally hypoplastic olfactory sulci. Two patients (13%) had a unilateral normal olfactory sulcus and hypoplastic olfactory sulcus. Three patients (19%) had normal olfactory sulci. Quantitative analysis showed that the volume of olfactory bulbs varied from 0 mm3 to 63.5 mm3, with a mean volume of 10.20 ± 18 mm3, and the mean depth of the olfactory sulcus varied from 0 mm to 12.22 mm, with a mean length of 4.85 ± 4.1 mm. Currently, there is no effective treatment for congenital anosmia. However, diagnosis of congenital anosmia is important, as its presence can lead to dangerous situations. Careful examination for hypogonadism is also required in people with anosmia. MRI examinations of the olfactory bulbs and sulci were useful for the diagnosis of congenital anosmia.

Learning pattern recognition and decision making in the insect brain

NASA Astrophysics Data System (ADS)

Huerta, R.

2013-01-01

We revise the current model of learning pattern recognition in the Mushroom Bodies of the insects using current experimental knowledge about the location of learning, olfactory coding and connectivity. We show that it is possible to have an efficient pattern recognition device based on the architecture of the Mushroom Bodies, sparse code, mutual inhibition and Hebbian leaning only in the connections from the Kenyon cells to the output neurons. We also show that despite the conventional wisdom that believes that artificial neural networks are the bioinspired model of the brain, the Mushroom Bodies actually resemble very closely Support Vector Machines (SVMs). The derived SVM learning rules are situated in the Mushroom Bodies, are nearly identical to standard Hebbian rules, and require inhibition in the output. A very particular prediction of the model is that random elimination of the Kenyon cells in the Mushroom Bodies do not impair the ability to recognize odorants previously learned.

Taste, olfactory, and food reward value processing in the brain.

PubMed

Rolls, Edmund T

2015-04-01

Complementary neuronal recordings in primates, and functional neuroimaging in humans, show that the primary taste cortex in the anterior insula provides separate and combined representations of the taste, temperature, and texture (including fat texture) of food in the mouth independently of hunger and thus of reward value and pleasantness. One synapse on, in a second tier of processing, in the orbitofrontal cortex, these sensory inputs are for some neurons combined by associative learning with olfactory and visual inputs, and these neurons encode food reward value on a continuous scale in that they only respond to food when hungry, and in that activations correlate linearly with subjective pleasantness. Cognitive factors, including word-level descriptions, and selective attention to affective value, modulate the representation of the reward value of taste and olfactory stimuli in the orbitofrontal cortex and a region to which it projects, the anterior cingulate cortex, a tertiary taste cortical area. The food reward representations formed in this way play an important role in the control of appetite, and food intake. Individual differences in these reward representations may contribute to obesity, and there are age-related differences in these value representations that shape the foods that people in different age groups find palatable. In a third tier of processing in medial prefrontal cortex area 10, decisions between stimuli of different reward value are taken, by attractor decision-making networks. Copyright © 2015 Elsevier Ltd. All rights reserved.

An insect-inspired model for visual binding I: learning objects and their characteristics.

PubMed

Northcutt, Brandon D; Dyhr, Jonathan P; Higgins, Charles M

2017-04-01

Visual binding is the process of associating the responses of visual interneurons in different visual submodalities all of which are responding to the same object in the visual field. Recently identified neuropils in the insect brain termed optic glomeruli reside just downstream of the optic lobes and have an internal organization that could support visual binding. Working from anatomical similarities between optic and olfactory glomeruli, we have developed a model of visual binding based on common temporal fluctuations among signals of independent visual submodalities. Here we describe and demonstrate a neural network model capable both of refining selectivity of visual information in a given visual submodality, and of associating visual signals produced by different objects in the visual field by developing inhibitory neural synaptic weights representing the visual scene. We also show that this model is consistent with initial physiological data from optic glomeruli. Further, we discuss how this neural network model may be implemented in optic glomeruli at a neuronal level.

Identification and Characterization of Pheromone Receptors and Interplay between Receptors and Pheromone Binding Proteins in the Diamondback Moth, Plutella xyllostella

PubMed Central

Sun, Mengjing; Liu, Yang; Walker, William B.; Liu, Chengcheng; Lin, Kejian; Gu, Shaohua; Zhang, Yongjun; Zhou, Jingjiang; Wang, Guirong

2013-01-01

Moths depend on olfactory cues such as sex pheromones to find and recognize mating partners. Pheromone receptors (PRs) and Pheromone binding proteins (PBPs) are thought to be associated with olfactory signal transduction of pheromonal compounds in peripheral olfactory reception. Here six candidate pheromone receptor genes in the diamondback moth, Plutella xyllostella were identified and cloned. All of the six candidate PR genes display male-biased expression, which is a typical characteristic of pheromone receptors. In the Xenopus-based functional study and in situ hybridization, PxylOR4 is defined as another pheromone receptor in addition to the previously characterized PxylOR1. In the study of interaction between PRs and PBPs, PxylPBPs could increase the sensitivity of the complex expressing oocyte cells to the ligand pheromone component while decreasing the sensitivity to pheromone analogs. We deduce that activating pheromone receptors in olfactory receptor neurons requires some role of PBPs to pheromone/PBP complex. If the chemical signal is not the pheromone component, but instead, a pheromone analog with a similar structure, the complex would have a decreased ability to activate downstream pheromone receptors. PMID:23626773

[Clinical observation of isolated congenital anosmia].

PubMed

Li, Li; Wei, Yong-xiang; Wang, Ning-yu; Miao, Xu-tao; Yang, Ling; Ge, Xiao-hui; Wu, Ying; Liu, Jia; Tian, Jun; Li, Kun-yan; Liu, Chun-li

2013-12-01

To introduce 8 patients with isolated congenital anosmia and to discuss the clinical manifestations, imaging characteristics and family characteristics of this rarely seen disorder. Eight patients with isolated congenital anosmia treated between April 2007 and April 2012 were reviewed retrospectively. There were 4 males and 4 females. A detailed medical history collection, physical examination, nasal endoscopy, T&T and Sniffin'Sticks subjective olfactory function tests, olfactory event-related potentials sinonasal computed tomography scan and sex hormones level monitoring were performed in all patients. Seven cases underwent magnetic resonance image of olfactory pathway examination. All patients were anosmia without evidence of other defects. ENT physical examination, nasal endoscopy and computed tomography scan were normal except 4 cases with obvious nasal septum deviation, 2 cases with concha bullosa. Subjective olfactory test indicated all of them were anosmia. Olfactory event-related potentials were obtained in only 1 patient. Magnetic resonance imaging revealed the smaller or atrophy olfactory bulb and olfactory tract in five cases, the absence of olfactory bulbs and tracts in two case. A female patient did not have MRI examination because of wearing IUDs. Detection of 8 patients of sex hormones were normal. Family characteristics: 3 patients showed family inheritance pattern. The diagnosis of isolated congenital anosmia should be based on chief complaint, medical history, physical examination, olfactory test, nasal endoscopy, olfactory testing, olfactory imaging and olfactory event-related potentials. Magnetic resonance image of olfactory pathway and olfactory event-related potentials have important value for the diagnosis. More attention should be paid to the genetic susceptibility of the family.

Morphometric and ultrastructural comparison of the olfactory system in elasmobranchs: the significance of structure-function relationships based on phylogeny and ecology.

PubMed

Schluessel, Vera; Bennett, Michael B; Bleckmann, Horst; Blomberg, Simon; Collin, Shaun P

2008-11-01

This study investigated the relationship between olfactory morphology, habitat occupancy, and lifestyle in 21 elasmobranch species in a phylogenetic context. Four measures of olfactory capability, that is, the number of olfactory lamellae, the surface area of the olfactory epithelium, the mass of the olfactory bulb, and the mass of the olfactory rosette were compared between individual species and groups, comprised of species with similar habitat and/or lifestyle. Statistical analyses using generalized least squares phylogenetic regression revealed that bentho-pelagic sharks and rays possess significantly more olfactory lamellae and larger sensory epithelial surface areas than benthic species. There was no significant correlation between either olfactory bulb or rosette mass and habitat type. There was also no significant difference between the number of lamellae or the size of the sensory surface area in groups comprised of species with similar diets, that is, groups preying predominantly on crustaceans, cephalopods, echinoderms, polychaetes, molluscs, or teleosts. However, some groups had significantly larger olfactory bulb or rosette masses than others. There was little evidence to support a correlation between phylogeny and morphology, indicating that differences in olfactory capabilities are the result of functional rather than phylogenetic adaptations. All olfactory epithelia exhibited microvilli and cilia, with microvilli in both nonsensory and sensory areas, and cilia only in sensory areas. Cilia over the sensory epithelia originated from supporting cells. In contrast to teleosts, which possess ciliated and microvillous olfactory receptor types, no ciliated olfactory receptor cells were observed. This is the first comprehensive study comparing olfactory morphology to several aspects of elasmobranch ecology in a phylogenetic context.

Associations of olfactory bulb and depth of olfactory sulcus with basal ganglia and hippocampus in patients with Parkinson's disease.

PubMed

Tanik, Nermin; Serin, Halil Ibrahim; Celikbilek, Asuman; Inan, Levent Ertugrul; Gundogdu, Fatma

2016-05-04

Parkinson's disease (PD) is a neurodegenerative disorder characterized by hyposmia in the preclinical stages. We investigated the relationships of olfactory bulb (OB) volume and olfactory sulcus (OS) depth with basal ganglia and hippocampal volumes. The study included 25 patients with PD and 40 age- and sex-matched control subjects. Idiopathic PD was diagnosed according to published diagnostic criteria. The Hoehn and Yahr (HY) scale, the motor subscale of the Unified Parkinson's Disease Rating Scale (UPDRS III), and the Mini-Mental State Examination (MMSE) were administered to participants. Volumetric measurements of olfactory structures, the basal ganglia, and hippocampus were performed using magnetic resonance imaging (MRI). OB volume and OS depth were significantly reduced in PD patients compared to healthy control subjects (p<0.001 and p<0.001, respectively). The OB and left putamen volumes were significantly correlated (p=0.048), and the depth of the right OS was significantly correlated with right hippocampal volume (p=0.018). We found significant correlations between OB and putamen volumes and OS depth and hippocampal volume. Our study is the first to demonstrate associations of olfactory structures with the putamen and hippocampus using MRI volumetric measurements. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Olfactory projection neuron pathways in two species of marine Isopoda (Peracarida, Malacostraca, Crustacea).

PubMed

Stemme, Torben; Eickhoff, René; Bicker, Gerd

2014-08-01

The neuroanatomy of the olfactory pathway has been intensely studied in many representatives of Malacostraca. Nevertheless, the knowledge about bilateral olfactory integration pathways is mainly based on Decapoda. Here, we investigated the olfactory projection neuron pathway of two marine isopod species, Saduria entomon and Idotea emarginata, by lipophilic dye injections into the olfactory neuropil. We show that both arms of the olfactory globular tract form a chiasm in the center of the brain, as known from several other crustaceans. Furthermore, the olfactory projection neurons innervate both the medulla terminalis and the hemiellipsoid body of the ipsi- and the contralateral hemisphere. Both protocerebral neuropils are innervated to a comparable extent. This is reminiscent of the situation in the basal decapod taxon Dendrobranchiata. Thus, we propose that an innervation by the olfactory globular tract of both the medulla terminalis and the hemiellipsoid body is characteristic of the decapod ground pattern, but also of the ground pattern of Caridoida. Copyright © 2014 Elsevier Ltd. All rights reserved.

Olfactory function and quality of life after olfaction rehabilitation in total laryngectomees.

PubMed

Santos, Christiane Gouvêa Dos; Bergmann, Anke; Coça, Kaliani Lima; Garcia, Angela Albuquerque; Valente, Tânia Cristina de Oliveira

2016-01-01

To evaluate the effects of olfaction rehabilitation in the olfactory function and quality of life of total laryngectomized patients. Pre-post intervention clinical study conducted with total laryngectomees submitted to olfaction rehabilitation by means of the Nasal Airflow-Inducing Maneuver (NAIM) using the University of Pennsylvania Smell Identification Test (UPSIT), Olfactory Acuity Questionnaires, a Monitoring Questionnaire, and the University of Washington Quality of Life Questionnaire (UW-QOL). Participants were 45 total laryngectomees. Before olfaction rehabilitation, 48.9% of the participants had their olfactic abilities classified as anosmia, 46.8% as microsmia, and 4.4% were considered within the normal range. After olfaction rehabilitation, 4.4% of the participants were classified as anosmia and 31.1% were within the normal range. In the Smell Identification Test, the mean score after rehabilitation showed statistically significant improvement. Reponses to the Olfactory Acuity Questionnaires after rehabilitation showed improvement in the frequency of perception regarding smell, taste, and the ability to smell perfume, food, leaking gas, and smoke, after learning the maneuver. Although the scores in the Quality of Life Questionnaire already indicated good quality of life before the surgery, post-intervention values were statistically significant. Olfaction rehabilitation improves olfactory function and has a positive impact on the activities of daily living and quality of life of total laryngectomized patients.

Development and evaluation of novel sensing materials for detecting food contamination

NASA Astrophysics Data System (ADS)

Sankaran, Sindhuja

Rapid detection of food-borne volatile organic compounds (VOCs) such as organic acids and alcohols released by bacterial pathogens is being used as an indicator for detecting bacterial contamination in food by our research group. One of our current research thrusts is to develop novel sensors that will be sensitive to specific compounds (at low operating temperature) associated with food safety. This study evaluates two approaches employed to develop sensors for detecting acid and alcohols at low concentrations. Chemoresistive and piezoelectric sensors were developed based on metal oxides and olfactory system based biomaterials, respectively to detect acetic acid, butanol, 3-methyl-1-butanol, 1-pentanol, and 1-hexanol. The metal oxide based sensors were developed by the sol-gel method. A zinc oxide (ZnO) sensor was found to be sensitive to acetic acid with lower detection limit ranging from 13-40 ppm. The three-layered dip-coated gold electrode based ZnO sensors had a LDL of 18 ppm for acetic acid detection. The ZnO-iron oxide (Fe2O3) based nanocomposite sensors were developed to detect butanol operating at 100°C. The 5% Fe/Zn mole ratio based ZnO-Fe2O3 nanocomposite sensors had high correlation coefficients (>0.90) of calibration curves, low butanol LDLs (26 +/- 7 ppm), and lower variation among the sensor responses. The ZnO and ZnO-Fe2O3 nanocomposite sensors showed potential to detect acetic acid and butanol at low concentrations, respectively at 100°C. QCM based olfactory sensors were developed from olfactory receptor and odorant binding protein based sequences to detect low concentrations of acetic acid and alcohols (3-methyl-1-butanol and 1-hexanol), respectively. The average LDLs for acetic acid as well as alcohols detection of the QCM sensors were < 5 ppm. The linear calibration curve based correlation coefficients of the QCM sensors were > 0.80. Finally, a computational simulation based peptide sequences was designed from olfactory receptors and evaluated as sensor material for the detection of alcohols at low concentrations. The results indicated that the QCM sensors exhibited a good sensitivity to 1-hexanol and 1-pentanol with the estimated LDLs in the range of 2-3 ppm and 3-5 ppm, respectively. This research work was successful in developing multiple novel sensing materials to detect alcohols and acid associated with meat contaminations at low concentrations.

A Behavioral and Genetic Dissection of Two Forms of Olfactory Plasticity in Caenorhabditis elegans: Adaptation and Habituation

PubMed Central

Bernhard, Nirit; van der Kooy, Derek

2000-01-01

Continuous presentation of an olfactory stimulus causes a decrement of the chemotaxis response in the nematode Caenorhabditis elegans. However, the differences between the learning process of habituation (a readily reversible decrease in behavioral response) and other types of olfactory plasticity such as adaptation (a decrement in response due to sensory fatigue, which cannot be dishabituated) have not been addressed. The volatile odorant diacetyl (DA) was used within a single paradigm to assess the distinct processes of olfactory adaptation and habituation. Preexposing and testing worms to 100% DA vapors caused a chemotaxis decrement that was not reversible despite the presentation of potentially dishabituating stimuli. This DA adaptation was abolished in worms with an odr-10 mutation (encoding a high-affinity DA receptor on the AWA neuron), even though naive chemotaxis remained unaffected. Conversely, DA adaptation remained intact in odr-1 mutants (defective in AWC neuron-mediated olfactory behavior), even though naive chemotaxis to DA decreased. Surprisingly, exposure to vapors of intermediate concentrations of DA (0.01% and 25%) did not cause worms to exhibit any response decrement. In contrast to preexposure to high DA concentrations, preexposure to low DA concentrations (0.001%) produced habituation of the chemotaxis response (a dishabituating stimulus could reverse the response decrement back to baseline levels). The distinct behavioral effects produced by DA preexposure highlight a concentration-dependent dissociation between two decremental olfactory processes: adaptation at high DA concentrations versus habituation at low DA concentrations. PMID:10940320

Regulation of inflammation-associated olfactory neuronal death and regeneration by the type II tumor necrosis factor receptor.

PubMed

Pozharskaya, Tatyana; Liang, Jonathan; Lane, Andrew P

2013-09-01

Olfactory loss is a debilitating symptom of chronic rhinosinusitis. To study the impact of inflammation on the olfactory system, the inducible olfactory inflammation (IOI) transgenic mouse was created in which inflammation can be turned on and off within the olfactory epithelium. In this study, the type II tumor necrosis factor (TNF) receptor (TNFR2) was knocked out, and the effect on the olfactory loss phenotype was assessed. IOI mice were bred to TNFR2 knockout mice to yield progeny IOI mice lacking the TNFR2 receptor (TNFR2(-/-) ). TNF-α expression was induced within the olfactory epithelium for 6 weeks to generate chronic inflammation. Olfactory function was assayed by electro-olfactogram (EOG), and olfactory tissue was processed for histology and immunohistochemical staining. Compared to IOI mice with wild-type TNFR2, IOI mice lacking the TNFR2 demonstrated similar levels of inflammatory infiltration and enlargement of the subepithelial layer. However, IOI-TNFR2(-/-) mice differed markedly in that the neuronal layer was largely preserved and active progenitor cell proliferation was present. Odorant responses were maintained in the IOI-TNFR2(-/-) mice, in contrast to IOI mice. TNFR2 is the minor receptor for TNF-α, but appears to play an important role in mediating TNF-induced disruption of the olfactory system. This finding suggests that neuronal death and inhibition of proliferation in CRS may be mediated by TNFR2 on olfactory neurons and progenitor cells. Further studies are needed to elucidate the subcellular pathways involved and develop novel therapies for treating olfactory loss in the setting of CRS. © 2013 ARS-AAOA, LLC.

Bt Toxin Cry1Ie Causes No Negative Effects on Survival, Pollen Consumption, or Olfactory Learning in Worker Honey Bees (Hymenoptera: Apidae).

PubMed

Dai, Ping-Li; Jia, Hui-Ru; Geng, Li-Li; Diao, Qing-Yun

2016-04-27

The honey bee (Apis mellifera L.) is a key nontarget insect in environmental risk assessments of insect-resistant genetically modified crops. In controlled laboratory conditions, we evaluated the potential effects of Cry1Ie toxin on survival, pollen consumption, and olfactory learning of young adult honey bees. We exposed worker bees to syrup containing 20, 200, or 20,000 ng/ml Cry1Ie toxin, and also exposed some bees to 48 ng/ml imidacloprid as a positive control for exposure to a sublethal concentration of a toxic product. Results suggested that Cry1Ie toxin carries no risk to survival, pollen consumption, or learning capabilities of young adult honey bees. However, during oral exposure to the imidacloprid treatments, honey bee learning behavior was affected and bees consumed significantly less pollen than the control and Cry1Ie groups. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Childhood Esthesioneuroblastoma Treatment (PDQ®)—Patient Version

Cancer.gov

Childhood esthesioneuroblastoma (olfactory neuroblastoma) treatment options may include surgery, radiation therapy, and/or chemotherapy. Learn more about the symptoms, diagnosis, prognosis, and treatment of childhood esthesioneuroblastoma in this expert-reviewed summary.

Reference memory, anxiety and estrous cyclicity in C57BL/6NIA mice are affected by age and sex.

PubMed

Frick, K M; Burlingame, L A; Arters, J A; Berger-Sweeney, J

2000-01-01

Age-related changes in learning and memory are common in rodents. However, direct comparisons of the effects of aging on learning and memory in both males and females are lacking. The present study examined whether memory deteriorates with increasing age in C57BL/6NIA mice, and whether age-related changes in learning and memory are similar in both sexes. Male and female mice (five, 17 and 25 months of age) were tested in a battery of behavioral tasks including the Morris water maze (spatial and non-spatial reference memory), simple odor discrimination (olfactory reference memory), plus maze (anxiety/exploration), locomotor activity, and basic reflexes. Five-month-old mice learned the water maze and odor discrimination tasks rapidly. Relative to five-month-old mice, 25-month-old mice exhibited impaired spatial and olfactory reference memory, but intact non-spatial reference memory. The spatial reference memory of 17-month-old mice was also impaired, but less so than 25-month mice. Seventeen-month-old mice exhibited intact non-spatial (visual and olfactory) reference memory. Five and 25-month-old mice had similar levels of plus maze exploration and locomotor activity, whereas 17-month-old mice were more active than both groups and were slightly less exploratory than five-month-old mice. Although sex differences were not observed in the five- and 25-month groups, 17-month-old females exhibited more impaired spatial reference memory and increased anxiety relative to 17-month-old males. Estrous cycling in females deteriorated significantly with increased age; all 25-month-old females had ceased cycling and 80% of 17-month-old females displayed either irregular or absent estrous cycling. This study is the first to directly compare age-related mnemonic decline in male and female mice. The results suggest that: (i) aged mice exhibit significant deficits in spatial and olfactory reference memory relative to young mice, whereas middle-aged mice exhibit only a moderate spatial memory deficit and; (ii) spatial reference memory decline begins at an earlier age in females than in males, a finding that may be related to the cessation of estrous cycling.

The olfactory neuron AWC promotes avoidance of normally palatable food following chronic dietary restriction

PubMed Central

Olofsson, Birgitta

2014-01-01

Changes in metabolic state alter foraging behavior and food preference in animals. Here, I show that normally attractive food becomes repulsive to Caenorhabditis elegans if animals are chronically undernourished as a result of alimentary tract defects. This behavioral plasticity is achieved in two ways: increased food leaving and induction of aversive behavior towards food. A particularly strong food avoider is defective in the chitin synthase that makes the pharyngeal lining. Food avoidance induced by underfeeding is mediated by cGMP signaling in the olfactory neurons AWC and AWB, and the gustatory neurons ASJ and ASK. Food avoidance is enhanced by increased population density and is reduced if the animals are unable to correctly interpret their nutritional state as a result of defects in the AMP kinase or TOR/S6kinase pathways. The TGF-β/DBL-1 pathway suppresses food avoidance and the cellular basis for this is distinct from its role in aversive olfactory learning of harmful food. This study suggests that nutritional state feedback via nutrient sensors, population size and olfactory neurons guides food preference in C. elegans. PMID:24577446

Evolutionary Genomics of Genes Involved in Olfactory Behavior in the Drosophila melanogaster Species Group

PubMed Central

Lavagnino, Nicolás; Serra, François; Arbiza, Leonardo; Dopazo, Hernán; Hasson, Esteban

2012-01-01

Previous comparative genomic studies of genes involved in olfactory behavior in Drosophila focused only on particular gene families such as odorant receptor and/or odorant binding proteins. However, olfactory behavior has a complex genetic architecture that is orchestrated by many interacting genes. In this paper, we present a comparative genomic study of olfactory behavior in Drosophila including an extended set of genes known to affect olfactory behavior. We took advantage of the recent burst of whole genome sequences and the development of powerful statistical tools to analyze genomic data and test evolutionary and functional hypotheses of olfactory genes in the six species of the Drosophila melanogaster species group for which whole genome sequences are available. Our study reveals widespread purifying selection and limited incidence of positive selection on olfactory genes. We show that the pace of evolution of olfactory genes is mostly independent of the life cycle stage, and of the number of life cycle stages, in which they participate in olfaction. However, we detected a relationship between evolutionary rates and the position that the gene products occupy in the olfactory system, genes occupying central positions tend to be more constrained than peripheral genes. Finally, we demonstrate that specialization to one host does not seem to be associated with bursts of adaptive evolution in olfactory genes in D. sechellia and D. erecta, the two specialists species analyzed, but rather different lineages have idiosyncratic evolutionary histories in which both historical and ecological factors have been involved. PMID:22346339

Olfactory short-term memory encoding and maintenance - an event-related potential study.

PubMed

Lenk, Steffen; Bluschke, Annet; Beste, Christian; Iannilli, Emilia; Rößner, Veit; Hummel, Thomas; Bender, Stephan

2014-09-01

This study examined whether the memory encoding and short term maintenance of olfactory stimuli is associated with neurophysiological activation patterns which parallel those described for sensory modalities such as vision and auditory. We examined olfactory event-related potentials in an olfactory change detection task in twenty-four healthy adults and compared the measured activation to that found during passive olfactory stimulation. During the early olfactory post-processing phase, we found a sustained negativity over bilateral frontotemporal areas in the passive perception condition which was enhanced in the active memory task. There was no significant lateralization in either experimental condition. During the maintenance interval at the end of the delay period, we still found sustained activation over bilateral frontotemporal areas which was more negative in trials with correct - as compared to incorrect - behavioural responses. This was complemented by a general significantly stronger frontocentral activation. Summarizing, we were able to show that olfactory short term memory involves a parallel sequence of activation as found in other sensory modalities. In addition to olfactory-specific frontotemporal activations in the memory encoding phase, we found slow cortical potentials over frontocentral areas during the memory maintenance phase indicating the activation of a supramodal memory maintenance system. These findings could represent the neurophysiological underpinning of the 'olfactory flacon', the olfactory counter-part to the visual sketchpad and phonological loop embedded in Baddeley's working memory model. Copyright © 2014 Elsevier Inc. All rights reserved.

Fus1 KO Mouse As a Model of Oxidative Stress-Mediated Sporadic Alzheimer's Disease: Circadian Disruption and Long-Term Spatial and Olfactory Memory Impairments

PubMed Central

Coronas-Samano, Guillermo; Baker, Keeley L.; Tan, Winston J. T.; Ivanova, Alla V.; Verhagen, Justus V.

2016-01-01

Insufficient advances in the development of effective therapeutic treatments of sporadic Alzheimer's Disease (sAD) to date are largely due to the lack of sAD-relevant animal models. While the vast majority of models do recapitulate AD's hallmarks of plaques and tangles by virtue of tau and/or beta amyloid overexpression, these models do not reflect the fact that in sAD (unlike familial AD) these genes are not risk factors per se and that other mechanisms like oxidative stress, metabolic dysregulation and inflammation play key roles in AD etiology. Here we characterize and propose the Fus1 KO mice that lack a mitochondrial protein Fus1/Tusc2 as a new sAD model. To establish sAD relevance, we assessed sAD related deficits in Fus1 KO and WT adult mice of 4–5 months old, the equivalent human age when the earliest cognitive and olfactory sAD symptoms arise. Fus1 KO mice showed oxidative stress (increased levels of ROS, decreased levels of PRDX1), disruption of metabolic homeostasis (decreased levels of ACC2, increased phosphorylation of AMPK), autophagy (decreased levels of LC3-II), PKC (decreased levels of RACK1) and calcium signaling (decreased levels of Calb2) in the olfactory bulb and/or hippocampus. Mice were behaviorally tested using objective and accurate video tracking (Noldus), in which Fus1 KO mice showed clear deficits in olfactory memory (decreased habituation/cross-habituation in the short and long term), olfactory guided navigation memory (inability to reduce their latency to find the hidden cookie), spatial memory (learning impairments on finding the platform in the Morris water maze) and showed more sleep time during the diurnal cycle. Fus1 KO mice did not show clear deficits in olfactory perception (cross-habituation), association memory (passive avoidance) or in species-typical behavior (nest building) and no increased anxiety (open field, light-dark box) or depression/anhedonia (sucrose preference) at this relatively young age. These neurobehavioral deficits of the Fus1 KO mice at this relatively young age are highly relevant to sAD, making them suitable for effective research on pharmacological targets in the context of early intervention of sAD. PMID:27895577

Effects of analgesics on olfactory function and the perception of intranasal trigeminal stimuli.

PubMed

Mizera, L; Gossrau, G; Hummel, T; Haehner, A

2017-01-01

There is some evidence suggesting that analgesics have an impact on human chemosensory function, especially opioids and cannabinoids are known to interfere with olfactory function. However, largely unknown is the effect of a long-term use of analgesics on the intranasal trigeminal system so far. Here, we investigated olfactory function and the perception of intranasal trigeminal stimuli in pain patients with long-term use of analgesics compared to age-matched healthy controls. For this purpose, a psychophysical approach was chosen to measure these sensory functions in 100 chronic pain patients and 95 controls. Olfactory testing was performed using the 'Sniffin' Sticks' test kit, which involves tests for odour threshold, odour discrimination and odour identification. Further, participants were asked to rate the intensity of trigeminal stimuli by using a visual analogue scale. We observed that the chronic use of pain medication was associated with significantly reduced perception of intranasal trigeminal stimuli and olfactory function compared to age-matched controls without intake of analgesics. Results indicate that non-opioid and opioid drugs, or a combination of both did not differ in their effects on chemosensory function. Further, after eliminating the effect of a co-existing depression and the use of co-analgesics, the negative influence of analgesics on olfactory function and trigeminal perception was still evident. The observed effect might be mediated due to interaction with opioid receptors in trigeminal ganglia and nuclei or due to trigeminal/olfactory interaction. As a practical consequence, patients should be made aware of a possible impairment of their olfactory and trigeminal function under long-term analgesic treatment. WHAT DOES THIS STUDY ADD?: We observed that the chronic use of pain medication was associated with significantly reduced olfactory function and perception of intranasal trigeminal stimuli compared to age-matched controls without intake of analgesics. Non-opioid and opioid drugs did not differ in their effects on chemosensory function. © 2016 European Pain Federation - EFIC®.

Aversive learning of odor-heat associations in ants.

PubMed

Desmedt, Lucie; Baracchi, David; Devaud, Jean-Marc; Giurfa, Martin; d'Ettorre, Patrizia

2017-12-15

Ants have recently emerged as useful models for the study of olfactory learning. In this framework, the development of a protocol for the appetitive conditioning of the maxilla-labium extension response (MaLER) provided the possibility of studying Pavlovian odor-food learning in a controlled environment. Here we extend these studies by introducing the first Pavlovian aversive learning protocol for harnessed ants in the laboratory. We worked with carpenter ants Camponotus aethiops and first determined the capacity of different temperatures applied to the body surface to elicit the typical aversive mandible opening response (MOR). We determined that 75°C is the optimal temperature to induce MOR and chose the hind legs as the stimulated body region because of their high sensitivity. We then studied the ability of ants to learn and remember odor-heat associations using 75°C as the unconditioned stimulus. We studied learning and short-term retention after absolute (one odor paired with heat) and differential conditioning (a punished odor versus an unpunished odor). Our results show that ants successfully learn the odor-heat association under a differential-conditioning regime and thus exhibit a conditioned MOR to the punished odor. Yet, their performance under an absolute-conditioning regime is poor. These results demonstrate that ants are capable of aversive learning and confirm previous findings about the different attentional resources solicited by differential and absolute conditioning in general. © 2017. Published by The Company of Biologists Ltd.

A putative vesicular transporter expressed in Drosophila mushroom bodies that mediates sexual behavior may define a novel neurotransmitter system

PubMed Central

Brooks, Elizabeth S.; Greer, Christina L.; Romero-Calderón, Rafael; Serway, Christine N.; Grygoruk, Anna; Haimovitz, Jasmine M.; Nguyen, Bac T.; Najibi, Rod; Tabone, Christopher J.; de Belle, J. Steven; Krantz, David E.

2011-01-01

Summary Storage and release of classical and amino acid neurotransmitters requires vesicular transporters. Some neurons lack known vesicular transporters, suggesting additional neurotransmitter systems remain unidentified. Insect mushroom bodies (MBs) are critical for several behaviors, including learning, but the neurotransmitters released by the intrinsic Kenyon cells (KCs) remain unknown. Likewise, KCs do not express a known vesicular transporter. We report the identification of a novel Drosophila gene portabella (prt) that is structurally similar to known vesicular transporters. Both larval and adult brains express PRT in the KCs of the MBs. Additional PRT cells project to the central complex and optic ganglia. prt mutation causes an olfactory learning deficit and an unusual defect in the male’s position during copulation that is rescued by expression in KCs. Since prt is expressed in neurons that lack other known vesicular transporters or neurotransmitters, it may define a previously unknown neurotransmitter system responsible for sexual behavior and a component of olfactory learning. PMID:22017990

Influence of olfactory and visual cover on nest site selection and nest success for grassland-nesting birds.

PubMed

Fogarty, Dillon T; Elmore, R Dwayne; Fuhlendorf, Samuel D; Loss, Scott R

2017-08-01

Habitat selection by animals is influenced by and mitigates the effects of predation and environmental extremes. For birds, nest site selection is crucial to offspring production because nests are exposed to extreme weather and predation pressure. Predators that forage using olfaction often dominate nest predator communities; therefore, factors that influence olfactory detection (e.g., airflow and weather variables, including turbulence and moisture) should influence nest site selection and survival. However, few studies have assessed the importance of olfactory cover for habitat selection and survival. We assessed whether ground-nesting birds select nest sites based on visual and/or olfactory cover. Additionally, we assessed the importance of visual cover and airflow and weather variables associated with olfactory cover in influencing nest survival. In managed grasslands in Oklahoma, USA, we monitored nests of Northern Bobwhite ( Colinus virginianus ), Eastern Meadowlark ( Sturnella magna ), and Grasshopper Sparrow ( Ammodramus savannarum ) during 2015 and 2016. To assess nest site selection, we compared cover variables between nests and random points. To assess factors influencing nest survival, we used visual cover and olfactory-related measurements (i.e., airflow and weather variables) to model daily nest survival. For nest site selection, nest sites had greater overhead visual cover than random points, but no other significant differences were found. Weather variables hypothesized to influence olfactory detection, specifically precipitation and relative humidity, were the best predictors of and were positively related to daily nest survival. Selection for overhead cover likely contributed to mitigation of thermal extremes and possibly reduced detectability of nests. For daily nest survival, we hypothesize that major nest predators focused on prey other than the monitored species' nests during high moisture conditions, thus increasing nest survival on these days. Our study highlights how mechanistic approaches to studying cover informs which dimensions are perceived and selected by animals and which dimensions confer fitness-related benefits.

Expression of calmodulin mRNA in rat olfactory neuroepithelium.

PubMed

Biffo, S; Goren, T; Khew-Goodall, Y S; Miara, J; Margolis, F L

1991-04-01

A calmodulin (CaM) cDNA was isolated by differential hybridization screening of a lambda gt10 library prepared from rat olfactory mucosa. This cDNA fragment, containing most of the open reading frame of the rat CaMI gene, was subcloned and used to characterize steady-state expression of CaM mRNA in rat olfactory neuroepithelium and bulb. Within the bulb mitral cells are the primary neuronal population expressing CaM mRNA. The major CaM mRNA expressed in the olfactory mucosa is 1.7 kb with smaller contributions from mRNAs of 4.0 and 1.4 kb. CaM mRNA was primarily associated with the olfactory neurons and, despite the cellular complexity of the tissue and the known involvement of CaM in diverse cellular processes, was only minimally evident in sustentacular cells, gland cells or respiratory epithelium. Following bulbectomy CaM mRNA declines in the olfactory neuroepithelium as does olfactory marker protein (OMP) mRNA. In contrast to the latter, CaM mRNA makes a partial recovery by one month after surgery. These results, coupled with those from in situ hybridization, indicate that CaM mRNA is expressed in both mature and immature olfactory neurons. The program regulating CaM gene expression in olfactory neurons is distinct from those controlling expression of B50/GAP43 in immature, or OMP in mature, neurons respectively.

Olfactory threshold increase in trigeminal neuralgia after balloon compression.

PubMed

Siqueira, S R D T; Nóbrega, J C M; Teixeira, M J; Siqueira, J T T

2006-12-01

Idiopathic trigeminal neuralgia (ITN) is a well-known disease often treated with neurosurgical procedures, which may produce sensorial abnormalities, such as numbness, dysesthesia and taste complaints. We studied 12 patients that underwent this technique, in order to verify pain, gustative and olfactory thresholds abnormalities, with a follow-up of 120 days. We compared the patients with a matched control group of 12 patients. Our results found a significant difference in the olfactory threshold at the immediate post-operative period (p=0.048). We concluded that injured trigeminal fibers are probably associated with the increase in the olfactory threshold after the surgery, supporting the sensorial interaction theory.

Association Between Olfactory Dysfunction and Amnestic Mild Cognitive Impairment and Alzheimer Disease Dementia.

PubMed

Roberts, Rosebud O; Christianson, Teresa J H; Kremers, Walter K; Mielke, Michelle M; Machulda, Mary M; Vassilaki, Maria; Alhurani, Rabe E; Geda, Yonas E; Knopman, David S; Petersen, Ronald C

2016-01-01

To increase the opportunity to delay or prevent mild cognitive impairment (MCI) or Alzheimer disease (AD) dementia, markers of early detection are essential. Olfactory impairment may be an important clinical marker and predictor of these conditions and may help identify persons at increased risk. To examine associations of impaired olfaction with incident MCI subtypes and progression from MCI subtypes to AD dementia. Participants enrolled in the population-based, prospective Mayo Clinic Study of Aging between 2004 and 2010 were clinically evaluated at baseline and every 15 months through 2014. Participants (N = 1630) were classified as having normal cognition, MCI (amnestic MCI [aMCI] and nonamnestic MCI [naMCI]), and dementia. We administered the Brief Smell Identification Test (B-SIT) to assess olfactory function. Mild cognitive impairment, AD dementia, and longitudinal change in cognitive performance measures. Of the 1630 participants who were cognitively normal at the time of the smell test, 33 died before follow-up and 167 were lost to follow-up. Among the 1430 cognitively normal participants included, the mean (SD) age was 79.5 (5.3) years, 49.4% were men, the mean duration of education was 14.3 years, and 25.4% were APOE ε4 carriers. Over a mean 3.5 years of follow-up, there were 250 incident cases of MCI among 1430 cognitively normal participants. We observed an association between decreasing olfactory identification, as measured by a decrease in the number of correct responses in B-SIT score, and an increased risk of aMCI. Compared with the upper B-SIT quartile (quartile [Q] 4, best scores), hazard ratios (HRs) (95% CI) were 1.12 (0.65-1.92) for Q3 (P = .68); 1.95 (1.25-3.03) for Q2 (P = .003); and 2.18 (1.36-3.51) for Q1 (P = .001) (worst scores; P for trend <.001) after adjustment for sex and education, with age as the time scale. There was no association with naMCI. There were 64 incident dementia cases among 221 prevalent MCI cases. The B-SIT score also predicted progression from aMCI to AD dementia, with a significant dose-response with worsening B-SIT quartiles. Compared with Q4, HR (95% CI) estimates were 3.02 (1.06-8.57) for Q3 (P = .04); 3.63 (1.19-11.10) for Q2 (P = .02); and 5.20 (1.90-14.20) for Q1 (P = .001). After adjusting for key predictors of MCI risk, B-SIT (as a continuous measure) remained a significant predictor of MCI (HR, 1.10 [95% CI, 1.04-1.16]; P < .001) and improved the model concordance. Olfactory impairment is associated with incident aMCI and progression from aMCI to AD dementia. These findings are consistent with previous studies that have reported associations of olfactory impairment with cognitive impairment in late life and suggest that olfactory tests have potential utility for screening for MCI and MCI that is likely to progress.

Intranasal Adeno-Associated Virus Mediated Gene Delivery and Expression of Human Iduronidase in the Central Nervous System: A Noninvasive and Effective Approach for Prevention of Neurologic Disease in Mucopolysaccharidosis Type I.

PubMed

Belur, Lalitha R; Temme, Alexa; Podetz-Pedersen, Kelly M; Riedl, Maureen; Vulchanova, Lucy; Robinson, Nicholas; Hanson, Leah R; Kozarsky, Karen F; Orchard, Paul J; Frey, William H; Low, Walter C; McIvor, R Scott

2017-07-01

Mucopolysaccharidosis type I (MPS I) is a progressive, multi-systemic, inherited metabolic disease caused by deficiency of α-L-iduronidase (IDUA). Current treatments for this disease are ineffective in treating central nervous system (CNS) disease due to the inability of lysosomal enzymes to traverse the blood-brain barrier. A noninvasive and effective approach was taken in the treatment of CNS disease by intranasal administration of an IDUA-encoding adeno-associated virus serotype 9 (AAV9) vector. Adult IDUA-deficient mice aged 3 months were instilled intranasally with AAV9-IDUA vector. Animals sacrificed 5 months post instillation exhibited IDUA enzyme activity levels that were up to 50-fold that of wild-type mice in the olfactory bulb, with wild-type levels of enzyme restored in all other parts of the brain. Intranasal treatment with AAV9-IDUA also resulted in the reduction of tissue glycosaminoglycan storage materials in the brain. There was strong IDUA immunofluorescence staining of tissue sections observed in the nasal epithelium and olfactory bulb, but there was no evidence of the presence of transduced cells in other portions of the brain. This indicates that reduction of storage materials most likely occurred as a result of enzyme diffusion from the olfactory bulb and the nasal epithelium into deeper areas of the brain. At 8 months of age, neurocognitive testing using the Barnes maze to assess spatial navigation demonstrated that treated IDUA-deficient mice were no different from normal control animals, while untreated IDUA-deficient mice exhibited significant learning and navigation deficits. This novel, noninvasive strategy for intranasal AAV9-IDUA instillation could potentially be used to treat CNS manifestations of human MPS I.

Olfactory neurons express a unique glycosylated form of the neural cell adhesion molecule (N-CAM)

PubMed Central

1990-01-01

mAb-based approaches were used to identify cell surface components involved in the development and function of the frog olfactory system. We describe here a 205-kD cell surface glycoprotein on olfactory receptor neurons that was detected with three mAbs: 9-OE, 5-OE, and 13- OE. mAb 9-OE immunoreactivity, unlike mAbs 5-OE and 13-OE, was restricted to only the axons and terminations of the primary sensory olfactory neurons in the frog nervous system. The 9-OE polypeptide(s) were immunoprecipitated and tested for cross-reactivity with known neural cell surface components including HNK-1, the cell adhesion molecule L1, and the neural cell adhesion molecule (N-CAM). These experiments revealed that 9-OE-reactive molecules were not L1 related but were a subset of the 200-kD isoforms of N-CAM. mAb 9-OE recognized epitopes associated with N-linked carbohydrate residues that were distinct from the polysialic acid chains present on the embryonic form of N-CAM. Moreover, 9-OE N-CAM was a heterogeneous population consisting of subsets both with and without the HNK-1 epitope. Thus, combined immunohistochemical and immunoprecipitation experiments have revealed a new glycosylated form of N-CAM unique to the olfactory system. The restricted spatial expression pattern of this N-CAM glycoform suggests a possible role in the unusual regenerative properties of this sensory system. PMID:2186048

Roles of Aminergic Neurons in Formation and Recall of Associative Memory in Crickets

PubMed Central

Mizunami, Makoto; Matsumoto, Yukihisa

2010-01-01

We review recent progress in the study of roles of octopaminergic (OA-ergic) and dopaminergic (DA-ergic) signaling in insect classical conditioning, focusing on our studies on crickets. Studies on olfactory learning in honey bees and fruit-flies have suggested that OA-ergic and DA-ergic neurons convey reinforcing signals of appetitive unconditioned stimulus (US) and aversive US, respectively. Our work suggested that this is applicable to olfactory, visual pattern, and color learning in crickets, indicating that this feature is ubiquitous in learning of various sensory stimuli. We also showed that aversive memory decayed much faster than did appetitive memory, and we proposed that this feature is common in insects and humans. Our study also suggested that activation of OA- or DA-ergic neurons is needed for appetitive or aversive memory recall, respectively. To account for this finding, we proposed a model in which it is assumed that two types of synaptic connections are strengthened by conditioning and are activated during memory recall, one type being connections from neurons representing conditioned stimulus (CS) to neurons inducing conditioned response and the other being connections from neurons representing CS to OA- or DA-ergic neurons representing appetitive or aversive US, respectively. The former is called stimulus–response (S–R) connection and the latter is called stimulus–stimulus (S–S) connection by theorists studying classical conditioning in vertebrates. Results of our studies using a second-order conditioning procedure supported our model. We propose that insect classical conditioning involves the formation of S–S connection and its activation for memory recall, which are often called cognitive processes. PMID:21119781

Annual life-history dependent seasonal differences in neural activity of the olfactory system between non-migratory and migratory songbirds.

PubMed

Rastogi, Ashutosh; Surbhi; Malik, Shalie; Rani, Sangeeta; Kumar, Vinod

2016-01-01

Present study investigated seasonal plasticity in neural activity of the olfactory system, and assessed whether this was influenced by differences in seasonal life-history states (LHSs) between the non-migratory and migratory birds. Brains of non-migratory Indian weaver birds and migratory redheaded buntings were processed for ZENK immunohistochemistry, a marker of neuronal activation, at the times of equinoxes (March, September) and solstices (June, December), which correspond with the periods of different seasonal LHSs during the year. Immunoreactivity was quantified in brain regions comprising the olfactory system viz. olfactory bulb (OB), anterior olfactory nucleus (AON), prepiriform cortex (CPP), lateral olfactory tract (LOT) and olfactory cortex (piriform cortex, CPI; lateral olfactory cortex, LOC). In weaver birds, ZENK-like immunoreactive (ZENK-lir) cells were significantly higher in all the brain areas during post-breeding season (September) than during the other seasons; OBs had higher neuronal activity in the breeding season (June), however. A similar neural activity pattern but at enhanced levels was found in migratory buntings almost all the year. These results for the first time show LHS-associated differences in the seasonal plasticity of a sensory system between the non-migratory and migratory songbirds. Copyright © 2015 Elsevier B.V. All rights reserved.

Preservation of olfaction in surgery of olfactory groove meningiomas.

PubMed

Jang, Woo-Youl; Jung, Shin; Jung, Tae-Young; Moon, Kyung-Sub; Kim, In-Young

2013-08-01

Olfaction is commonly considered as secondary among the sensory functions, perhaps reflecting a lack of interest in sparing olfaction after surgery for the olfactory groove meningiomas (OGM). However, considering the repercussions of olfaction for the quality of life, the assessment of post-operative olfaction should be necessary. We retrospectively reviewed the olfactory outcome in patients with OGM and investigated the factors associated with sparing the post-operative olfaction. Between 1993 and 2012, 40 patients with OGM underwent surgical resection and estimated the olfactory function using the Korean version of "Sniffin'Sticks" test (KVSS). Variable factors, such as tumor size, degree of preoperative edema, tumor consistency, preoperative olfactory function, surgical approaches, patient's age, and gender were analyzed with attention to the post-operative olfactory function. Anatomical and functional preservation of olfactory structures were achieved in 26 patients (65%) and 22 patients (55%), respectively. Among the variable factors, size of tumor was significant related to the preservation of post-operative olfaction. (78.6% in size<4 cm and 42.3% in size>4 cm, p=0.035). Sparing the olfaction was significantly better in patients without preoperative olfactory dysfunction (84.6%) compared with ones with preoperative olfactory dysfunction (40.7%, p=0.016). The frontolateral approach achieved much more excellent post-operative olfactory function (71.4%) than the bifrontal approach (36.8%, p=0.032). If the tumor was smaller than 4 cm and the patients did not present olfactory dysfunction preoperatively, the possibility of sparing the post-operative olfaction was high. Among the variable surgical approaches, frontolateral route may be preferable sparing the post-operative olfaction. Copyright © 2012 Elsevier B.V. All rights reserved.

Appetitive but not aversive olfactory conditioning modifies antennal movements in honeybees

PubMed Central

Cholé, Hanna; Junca, Pierre

2015-01-01

In honeybees, two olfactory conditioning protocols allow the study of appetitive and aversive Pavlovian associations. Appetitive conditioning of the proboscis extension response (PER) involves associating an odor, the conditioned stimulus (CS) with a sucrose solution, the unconditioned stimulus (US). Conversely, aversive conditioning of the sting extension response (SER) involves associating the odor CS with an electric or thermal shock US. Each protocol is based on the measure of a different behavioral response (proboscis versus sting) and both only provide binary responses (extension or not of the proboscis or sting). These limitations render the measure of the acquired valence of an odor CS difficult without testing the animals in a freely moving situation. Here, we studied the effects of both olfactory conditioning protocols on the movements of the antennae, which are crucial sensory organs for bees. As bees’ antennae are highly mobile, we asked whether their movements in response to an odorant change following appetitive or aversive conditioning and if so, do odor-evoked antennal movements contain information about the acquired valence of the CS? We implemented a tracking system for harnessed bees’ antennal movements based on a motion capture principle at a high frequency rate. We observed that differential appetitive conditioning had a strong effect on antennal movements. Bees responded to the reinforced odorant with a marked forward motion of the antennae and a strong velocity increase. Conversely, differential aversive conditioning had no associative effect on antennal movements. Rather than revealing the acquired valence of an odorant, antennal movements may represent a novel conditioned response taking place during appetitive conditioning and may provide a possible advantage to bees when foraging in natural situations. PMID:26572651

Long term serious olfactory loss in colds and/or flu.

PubMed

de Haro-Licer, Josep; Roura-Moreno, Jordi; Vizitiu, Anabella; González-Fernández, Adela; González-Ares, Josep Antón

2013-01-01

In the general population, we can find 2-3% of lifelong olfactory disorders (from hyposmia to anosmia). Two of the most frequent aetiologies are the common cold and flu. The aim of this study was to show the degree of long-term olfactory dysfunction caused by a cold or flu. This study was based on 240 patients, with olfactory loss caused only by flu or a cold. We excluded all patients with concomitant illness (66 patients), the rest of patients (n=174) consisted of 51 men (29.3%) and 123 women (70.7%). They all underwent olfactometry study (i and v cranial nerve) and a nasal sinus computed tomography scan, as well as magnetic resonance imaging of the brain. Results were compared with a control group (n=120). Very significant differences in levels of olfactory impairment for the olfactory nerve (P<.00001) and trigeminal nerve (P<.0001) were confirmed. People that suffer olfactory dysfunction for more than 6 months, from flu or a cold, present serious impairment of olfactory abilities. Copyright © 2012 Elsevier España, S.L. All rights reserved.

Differential Olfactory Identification in Children with Autism and Asperger's Disorder: A Comparative and Longitudinal Study

ERIC Educational Resources Information Center

May, Tamara; Brewer, Warrick J.; Rinehart, Nicole J.; Enticott, Peter G.; Brereton, Avril V.; Tonge, Bruce J.

2011-01-01

Key theories of autism implicate orbitofrontal cortex (OFC) compromise, while olfactory identification (OI) deficits are associated with OFC dysfunction. This study aimed to complete a 5-year follow-up of children with high-functioning autism (HFA) who previously lacked the normal age-OI association; and compare unirhinal-OI in children with HFA,…

Olfactory abnormalities in Huntington's disease: decreased plasticity in the primary olfactory cortex of R6/1 transgenic mice and reduced olfactory discrimination in patients.

PubMed

Lazic, Stanley E; Goodman, Anna O G; Grote, Helen E; Blakemore, Colin; Morton, A Jennifer; Hannan, Anthony J; van Dellen, Anton; Barker, Roger A

2007-06-02

Reduced neuronal plasticity in the striatum, hippocampus, and neocortex is a common feature of transgenic mouse models of Huntington's disease (HD). Doublecortin (DCX) and polysialylated neural cell adhesion molecule (PSA-NCAM) are associated with structural plasticity in the adult mammalian brain, are markers of newly formed neurons in the dentate gyrus of the adult hippocampus, and are highly expressed in primary olfactory (piriform) cortex. Animal studies have demonstrated that a reduction in plasticity in the piriform cortex is associated with a selective impairment in odour discrimination. Therefore, the number of DCX and PSA-NCAM immunoreactive cells in the piriform cortex were quantified as measures of plasticity in early stage (fifteen week old) R6/1 transgenic HD mice. The transgenic mice had a large reduction in the number of DCX and PSA-NCAM immunoreactive cells in the piriform cortex, similar to that previously reported in the R6/2 mice. We also tested whether odour discrimination, as well as identification and detection, were impaired in HD patients and found that patients (at a similar disease stage as the mice) had an impairment in odour discrimination and identification, but not odour detection. These results suggest that olfactory impairments observed in HD patients may be the result of reduced plasticity in the primary olfactory cortex.

Effects of 20 mg oral Δ9-tetrahydrocannabinol on the olfactory function of healthy volunteers*

PubMed Central

Walter, Carmen; Oertel, Bruno G; Ludyga, Dagmar; Ultsch, Alfred; Hummel, Thomas; Lötsch, Jörn

2014-01-01

Aims Olfactory loss impairs the patient's quality of life. In individualized therapies, olfactory drug effects gain clinical importance. Molecular evidence suggests that among drugs with potential olfactory effects is Δ9-tetrahydrocannabinol (THC), which is approved for several indications, including neuropathic pain or analgesia in cancer patients. The present study aimed at assessing the olfactory effects of THC to be expected during analgesic treatment. Methods The effects of 20 mg oral THC on olfaction were assessed in a placebo-controlled, randomized cross-over study in healthy volunteers. Using an established olfactory test (Sniffin' Sticks), olfactory thresholds, odour discrimination and odour identification were assessed in 15 subjects at baseline and 2 h after THC administration. Results Δ9-Tetrahydrocannabinol impaired the performance of subjects (n = 15) in the olfactory test. Specifically, olfactory thresholds were increased and odour discrimination performance was reduced. This resulted in a significant drop in composite threshold, discrimination, identification (TDI) olfactory score by 5.5 points (from 37.7 ± 4.2 to 32.2 ± 5.6, 95% confidence interval for differences THC vs. placebo, −7.8 to −2.0, P = 0.003), which is known to be a subjectively perceptible impairment of olfactory function. Conclusions Considering the resurgence of THC in medical use for several pathological conditions, the present results indicate that THC-based analgesics may be accompanied by subjectively noticeable reductions in olfactory acuity. In particular, for patients relying on their sense of smell, this might be relevant information for personalized therapy strategies. PMID:24802974

Effects of 20 mg oral Δ(9) -tetrahydrocannabinol on the olfactory function of healthy volunteers.

PubMed

Walter, Carmen; Oertel, Bruno G; Ludyga, Dagmar; Ultsch, Alfred; Hummel, Thomas; Lötsch, Jörn

2014-11-01

Olfactory loss impairs the patient's quality of life. In individualized therapies, olfactory drug effects gain clinical importance. Molecular evidence suggests that among drugs with potential olfactory effects is Δ(9) -tetrahydrocannabinol (THC), which is approved for several indications, including neuropathic pain or analgesia in cancer patients. The present study aimed at assessing the olfactory effects of THC to be expected during analgesic treatment. The effects of 20 mg oral THC on olfaction were assessed in a placebo-controlled, randomized cross-over study in healthy volunteers. Using an established olfactory test (Sniffin' Sticks), olfactory thresholds, odour discrimination and odour identification were assessed in 15 subjects at baseline and 2 h after THC administration. Δ(9) -Tetrahydrocannabinol impaired the performance of subjects (n = 15) in the olfactory test. Specifically, olfactory thresholds were increased and odour discrimination performance was reduced. This resulted in a significant drop in composite threshold, discrimination, identification (TDI) olfactory score by 5.5 points (from 37.7 ± 4.2 to 32.2 ± 5.6, 95% confidence interval for differences THC vs. placebo, -7.8 to -2.0, P = 0.003), which is known to be a subjectively perceptible impairment of olfactory function. Considering the resurgence of THC in medical use for several pathological conditions, the present results indicate that THC-based analgesics may be accompanied by subjectively noticeable reductions in olfactory acuity. In particular, for patients relying on their sense of smell, this might be relevant information for personalized therapy strategies. © 2014 The British Pharmacological Society.

The Association Between Olfaction and Depression: A Systematic Review.

PubMed

Kohli, Preeti; Soler, Zachary M; Nguyen, Shaun A; Muus, John S; Schlosser, Rodney J

2016-07-01

Previous studies on the relationship between olfaction and depression have revealed mixed results. In addition, few have focused on the reciprocity of this association. The aim of this study is to combine depression and olfactory data in two separate patient populations to further understand their association. A systematic literature review was conducted using 3 online databases to identify studies correlating olfaction and depression in patients presenting with either primary depression or primary olfactory dysfunction. For the depressed population, weighted means and standard deviations for the Sniffin' Sticks Test and the 40-item Smell Identification Test were combined using 10 studies. For the olfactory dysfunction population, weighted means of Beck's Depression Inventory were combined using 3 studies. Independent t-tests were used to compare differences between groups. Comparing primary depressed patients with controls, depressed patients showed decreased scores in olfactory threshold (6.31±1.38 vs. 6.78±0.88, P = 0.0005), discrimination (12.05±1.44 vs. 12.66±1.36, P = 0.0073), identification (12.57±0.74 vs. 12.98±0.90, P < 0.0001), and 40-Item Smell Identification Test (35.31±1.91 vs. 37.41±1.45, P < 0.0001). In patients with primary olfactory dysfunction, Beck's Depression Inventory scores were significantly different between patients classified as normosmics, hyposmics and anosmics (5.21±4.73 vs. 10.93±9.25 vs. 14.15±5.39, P ≤ 0.0274 for all 3 comparisons). In conclusion, patients with depression have reduced olfactory performance when compared with the healthy controls and conversely, patients with olfactory dysfunction, have symptoms of depression that worsen with severity of smell loss. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Sensory memory for odors is encoded in spontaneous correlated activity between olfactory glomeruli.

PubMed

Galán, Roberto F; Weidert, Marcel; Menzel, Randolf; Herz, Andreas V M; Galizia, C Giovanni

2006-01-01

Sensory memory is a short-lived persistence of a sensory stimulus in the nervous system, such as iconic memory in the visual system. However, little is known about the mechanisms underlying olfactory sensory memory. We have therefore analyzed the effect of odor stimuli on the first odor-processing network in the honeybee brain, the antennal lobe, which corresponds to the vertebrate olfactory bulb. We stained output neurons with a calcium-sensitive dye and measured across-glomerular patterns of spontaneous activity before and after a stimulus. Such a single-odor presentation changed the relative timing of spontaneous activity across glomeruli in accordance with Hebb's theory of learning. Moreover, during the first few minutes after odor presentation, correlations between the spontaneous activity fluctuations suffice to reconstruct the stimulus. As spontaneous activity is ubiquitous in the brain, modifiable fluctuations could provide an ideal substrate for Hebbian reverberations and sensory memory in other neural systems.

Translating basic research into clinical practice or what else do we have to learn about olfactory ensheathing cells?

PubMed

Radtke, Christine; Wewetzer, Konstantin

2009-06-12

Olfactory ensheathing cells (OECs) are Schwann cell-like glial cells of the olfactory system that have been shown to promote axonal regeneration and remyelination in a variety of different lesion paradigms. It is still a matter of debate in how far OECs differ from Schwann cells regarding their regenerative potential and molecular setup. The fact that OECs have been already used for transplantation in humans may imply that the need of the hour is the fine-tuning of clinical application details rather than to cross the bridge between laboratory animal and man. Considering the therapeutic transplantation of OECs, however, the basic question to date is not 'how' to translate but rather 'what' to translate into clinical practice. The aim of the present article is to provide a summary of the current literature and to define the open issues relevant for translating basic research on OECs into clinical practice.

Brain structure is changed in congenital anosmia.

PubMed

Frasnelli, Johannes; Fark, Therese; Lehmann, Jacqueline; Gerber, Johannes; Hummel, Thomas

2013-12-01

Olfactory function in healthy people correlates with structural features of both the olfactory bulb and higher order olfactory processing areas, but we do not yet know how congenital anosmia affects these latter structures. In order to examine this question closer, we acquired T1 weighted magnetic resonance images from 17 subjects with congenital anosmia and from 17 age- and sex-matched controls. We compared white and gray matter volumes as well as cortical thickness between both groups. We found subjects with congenital anosmia to exhibit larger gray matter volumes in the left entorhinal and piriform cortices. Further, they had thicker orbitofrontal cortices bilaterally. Their left piriform cortex was also thicker than that of controls. These findings are in contrast to those observed in acquired anosmia, where reduced olfactory function is associated with reduced volumes and thickness. However, they fit well with observations from other sensory systems, e.g., vision, where congenital sensory loss is associated with a thicker primary cortex. This finding has been attributed to reduced or absent synaptic pruning as a result of missing peripheral sensory input. Our findings suggest that similar mechanisms take place in the olfactory system. © 2013.

Positive relationship between odor identification and affective responses of negatively valenced odors

PubMed Central

Martinec Nováková, Lenka; Plotěná, Dagmar; Roberts, S. Craig; Havlíček, Jan

2015-01-01

Hedonic ratings of odors and olfactory preferences are influenced by a number of modulating factors, such as prior experience and knowledge about an odor’s identity. The present study addresses the relationship between knowledge about an odor’s identity due to prior experience, assessed by means of a test of cued odor identification, and odor pleasantness ratings in children who exhibit ongoing olfactory learning. Ninety-one children aged 8–11 years rated the pleasantness of odors in the Sniffin’ Sticks test and, subsequently, took the odor identification test. A positive association between odor identification and pleasantness was found for two unpleasant food odors (garlic and fish): higher pleasantness ratings were exhibited by those participants who correctly identified these odors compared to those who failed to correctly identify them. However, we did not find a similar effect for any of the more pleasant odors. The results of this study suggest that pleasantness ratings of some odors may be modulated by the knowledge of their identity due to prior experience and that this relationship might be more evident in unpleasant odors. PMID:26029143

Evolution, Discovery, and Interpretations of Arthropod Mushroom Bodies

PubMed Central

Strausfeld, Nicholas J.; Hansen, Lars; Li, Yongsheng; Gomez, Robert S.; Ito, Kei

1998-01-01

Mushroom bodies are prominent neuropils found in annelids and in all arthropod groups except crustaceans. First explicitly identified in 1850, the mushroom bodies differ in size and complexity between taxa, as well as between different castes of a single species of social insect. These differences led some early biologists to suggest that the mushroom bodies endow an arthropod with intelligence or the ability to execute voluntary actions, as opposed to innate behaviors. Recent physiological studies and mutant analyses have led to divergent interpretations. One interpretation is that the mushroom bodies conditionally relay to higher protocerebral centers information about sensory stimuli and the context in which they occur. Another interpretation is that they play a central role in learning and memory. Anatomical studies suggest that arthropod mushroom bodies are predominately associated with olfactory pathways except in phylogenetically basal insects. The prominent olfactory input to the mushroom body calyces in more recent insect orders is an acquired character. An overview of the history of research on the mushroom bodies, as well as comparative and evolutionary considerations, provides a conceptual framework for discussing the roles of these neuropils. PMID:10454370

Olfactory Performance in a Large Sample of Early-Blind and Late-Blind Individuals.

PubMed

Sorokowska, Agnieszka

2016-10-01

Previous examinations of olfactory sensitivity in blind people have produced contradictory findings. Thus, whether visual impairment is associated with increased olfactory abilities is unclear. In the present investigation, I aimed to resolve the existing questions via a relatively large-scale study comprising early-blind (N = 43), and late-blind (N = 41) and sighted (N = 84) individuals matched in terms of gender and age. To compare the results with those of previous studies, I combined data from a free odor identification test, extensive psychophysical testing (Sniffin' Sticks test), and self-assessed olfactory performance. The analyses revealed no significant effects of sight on olfactory threshold, odor discrimination, cued identification, or free identification scores; neither was the performance of the early-blind and late-blind participants significantly different. Additionally, the self-assessed olfactory abilities of the blind people were no different than those of the sighted people. These results suggest that sensory compensation in visually impaired is not pronounced with regards to olfactory abilities as measured by standardized smell tests. © The Author 2016. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Neural correlates of olfactory and visual memory performance in 3D-simulated mazes after intranasal insulin application.

PubMed

Brünner, Yvonne F; Rodriguez-Raecke, Rea; Mutic, Smiljana; Benedict, Christian; Freiherr, Jessica

2016-10-01

This fMRI study intended to establish 3D-simulated mazes with olfactory and visual cues and examine the effect of intranasally applied insulin on memory performance in healthy subjects. The effect of insulin on hippocampus-dependent brain activation was explored using a double-blind and placebo-controlled design. Following intranasal administration of either insulin (40IU) or placebo, 16 male subjects participated in two experimental MRI sessions with olfactory and visual mazes. Each maze included two separate runs. The first was an encoding maze during which subjects learned eight olfactory or eight visual cues at different target locations. The second was a recall maze during which subjects were asked to remember the target cues at spatial locations. For eleven included subjects in the fMRI analysis we were able to validate brain activation for odor perception and visuospatial tasks. However, we did not observe an enhancement of declarative memory performance in our behavioral data or hippocampal activity in response to insulin application in the fMRI analysis. It is therefore possible that intranasal insulin application is sensitive to the methodological variations e.g. timing of task execution and dose of application. Findings from this study suggest that our method of 3D-simulated mazes is feasible for studying neural correlates of olfactory and visual memory performance. Copyright © 2016 Elsevier Inc. All rights reserved.

Anosmia leads to a loss of gray matter in cortical brain areas.

PubMed

Bitter, Thomas; Gudziol, Hilmar; Burmeister, Hartmut Peter; Mentzel, Hans-Joachim; Guntinas-Lichius, Orlando; Gaser, Christian

2010-06-01

Chronic olfactory disorders, including the complete loss of the sense of smell (anosmia), are common. Using voxel-based morphometry (VBM) in magnetic resonance imaging (MRI), structural changes in the cerebral gray matter (GM) of a group of patients with anosmia compared with a normosmic, healthy control group were evaluated. Patients with anosmia presented a significant decrease of GM volume mainly in the nucleus accumbens with adjacent subcallosal gyrus, in the medial prefrontal cortex (MPC) including the middle and anterior cingulate cortices, and in the dorsolateral prefrontal cortex (dlPFC). These areas are part of the limbic loop of the basal ganglia and except the dlPFC secondary olfactory areas. They also play an important role in many neurological diseases. Furthermore, volume decreases in smaller areas like the piriform cortex, insular cortex, orbitofrontal cortex, hippocampus, parahippocampal gyrus, supramarginal gyrus, and cerebellum could be seen. Longer disease duration was associated with a stronger atrophy in the described areas. No local increases in the GM volume could be observed. A comparison with results of an additionally executed functional MRI study on olfaction in healthy subjects was performed to evaluate the significance of the observed atrophy areas in cerebral olfactory processing. To our knowledge, this is the first study on persisting structural changes in cortical GM volume after complete olfactory loss.

First demonstration of olfactory learning and long term memory in honey bee queens.

PubMed

Gong, Zhiwen; Tan, Ken; Nieh, James C

2018-05-18

As the primary source of colony reproduction, social insect queens play a vital role. However, the cognitive abilities of queens are not well understood, although queen learning and memory are essential in multiple species such as honey bees, in which virgin queens must leave the nest and then successful learn to navigate back over repeated nuptial flights. Honey bee queen learning has never been previously demonstrated. We therefore tested olfactory learning in queens and workers and examined the role of DNA methylation, which plays a key role in long term memory formation. We provide the first evidence that honey bee queens have excellent learning and memory. The proportion of honey bee queens that exhibited learning was 5-fold higher than workers at every tested age and, for memory, 4-fold higher than workers at a very young age. DNA methylation may play a key role in this queen memory because queens exhibiting remote memory had a more consistent elevation in Dnmt3 gene expression as compared to workers. Both castes also showed excellent remote memory (7 day memory), which was reduced by 14-20% by the DNA methylation inhibitor, zebularine. Given that queens live about 10-fold longer than workers, these results suggest that queens can serve as an excellently long-term reservoir of colony memory. © 2018. Published by The Company of Biologists Ltd.

Transient uptake of serotonin by newborn olfactory projection neurons

PubMed Central

Beltz, Barbara S.; Benton, Jeanne L.; Sullivan, Jeremy M.

2001-01-01

A life-long turnover of sensory and interneuronal populations has been documented in the olfactory pathways of both vertebrates and invertebrates, creating a situation where the axons of new afferent and interneuronal populations must insert into a highly specialized glomerular neuropil. A dense serotonergic innervation of the primary olfactory processing areas where these neurons synapse also is a consistent feature across species. Prior studies in lobsters have shown that serotonin promotes the branching of olfactory projection neurons. This paper presents evidence that serotonin also regulates the proliferation and survival of projection neurons in lobsters, and that the serotonergic effects are associated with a transient uptake of serotonin into newborn neurons. PMID:11675504

[Radiological findings in congenital anosmia: a case report].

PubMed

Sánchez-Pérez, María; Recio-Rodríguez, Manuel; Jiménez-De la Peña, Mar; Carrascoso-Arranz, Javier; Martínez-De Vega, Vicente

2011-07-16

Hypoplasia of the olfactory tracts and bulbs is a rare cause of anosmia in the paediatric population. In most cases it is usually due to an acquired cause and in only a few is it associated to chromosomal disorders (Kallman's syndrome, among others). A 10-year-old boy with no chromosomal disorders and a family history of anosmia, who visited because of isolated anosmia; a magnetic resonance scan revealed bilateral hypoplasia of the olfactory tracts and bulbs. Magnetic resonance imaging allows the anatomy of the olfactory tract to be studied in detail and this makes it a valuable tool in the diagnosis of structural abnormalities in cases of olfactory disorders and also in the planning of treatment.

Reorganization of neuronal circuits of the central olfactory system during postprandial sleep

PubMed Central

Yamaguchi, Masahiro; Manabe, Hiroyuki; Murata, Koshi; Mori, Kensaku

2013-01-01

Plastic changes in neuronal circuits often occur in association with specific behavioral states. In this review, we focus on an emerging view that neuronal circuits in the olfactory system are reorganized along the wake-sleep cycle. Olfaction is crucial to sustaining the animals' life, and odor-guided behaviors have to be newly acquired or updated to successfully cope with a changing odor world. It is therefore likely that neuronal circuits in the olfactory system are highly plastic and undergo repeated reorganization in daily life. A remarkably plastic feature of the olfactory system is that newly generated neurons are continually integrated into neuronal circuits of the olfactory bulb (OB) throughout life. New neurons in the OB undergo an extensive selection process, during which many are eliminated by apoptosis for the fine tuning of neuronal circuits. The life and death decision of new neurons occurs extensively during a short time window of sleep after food consumption (postprandial sleep), a typical daily olfactory behavior. We review recent studies that explain how olfactory information is transferred between the OB and the olfactory cortex (OC) along the course of the wake-sleep cycle. Olfactory sensory input is effectively transferred from the OB to the OC during waking, while synchronized top-down inputs from the OC to the OB are promoted during the slow-wave sleep. We discuss possible neuronal circuit mechanisms for the selection of new neurons in the OB, which involves the encoding of olfactory sensory inputs and memory trace formation during waking and internally generated activities in the OC and OB during subsequent sleep. The plastic changes in the OB and OC are well coordinated along the course of olfactory behavior during wakefulness and postbehavioral rest and sleep. We therefore propose that the olfactory system provides an excellent model in which to understand behavioral state-dependent plastic mechanisms of the neuronal circuits in the brain. PMID:23966911

Smelling directions: Olfaction modulates ambiguous visual motion perception

PubMed Central

Kuang, Shenbing; Zhang, Tao

2014-01-01

Senses of smells are often accompanied by simultaneous visual sensations. Previous studies have documented enhanced olfactory performance with concurrent presence of congruent color- or shape- related visual cues, and facilitated visual object perception when congruent smells are simultaneously present. These visual object-olfaction interactions suggest the existences of couplings between the olfactory pathway and the visual ventral processing stream. However, it is not known if olfaction can modulate visual motion perception, a function that is related to the visual dorsal stream. We tested this possibility by examining the influence of olfactory cues on the perceptions of ambiguous visual motion signals. We showed that, after introducing an association between motion directions and olfactory cues, olfaction could indeed bias ambiguous visual motion perceptions. Our result that olfaction modulates visual motion processing adds to the current knowledge of cross-modal interactions and implies a possible functional linkage between the olfactory system and the visual dorsal pathway. PMID:25052162

Default Mode Network (DMN) Deactivation during Odor-Visual Association

PubMed Central

Karunanayaka, Prasanna R.; Wilson, Donald A.; Tobia, Michael J.; Martinez, Brittany; Meadowcroft, Mark; Eslinger, Paul J.; Yang, Qing X.

2017-01-01

Default mode network (DMN) deactivation has been shown to be functionally relevant for goal-directed cognition. In this study, we investigated the DMN’s role during olfactory processing using two complementary functional magnetic resonance imaging (fMRI) paradigms with identical timing, visual-cue stimulation and response monitoring protocols. Twenty-nine healthy, non-smoking, right-handed adults (mean age = 26±4 yrs., 16 females) completed an odor-visual association fMRI paradigm that had two alternating odor+visual and visual-only trial conditions. During odor+visual trials, a visual cue was presented simultaneously with an odor, while during visual-only trial conditions the same visual cue was presented alone. Eighteen of the 29 participants (mean age = 27.0 ± 6.0 yrs.,11 females) also took part in a control no-odor fMRI paradigm that consisted of visual-only trial conditions which were identical to the visual-only trials in the odor-visual association paradigm. We used Independent Component Analysis (ICA), extended unified structural equation modeling (euSEM), and psychophysiological interaction (PPI) to investigate the interplay between the DMN and olfactory network. In the odor-visual association paradigm, DMN deactivation was evoked by both the odor+visual and visual-only trial conditions. In contrast, the visual-only trials in the no-odor paradigm did not evoke consistent DMN deactivation. In the odor-visual association paradigm, the euSEM and PPI analyses identified a directed connectivity between the DMN and olfactory network which was significantly different between odor+visual and visual-only trial conditions. The results support a strong interaction between the DMN and olfactory network and highlights DMN’s role in task-evoked brain activity and behavioral responses during olfactory processing. PMID:27785847

Sexual odor preference and dopamine release in the nucleus accumbens by estrous olfactory cues in sexually naïve and experienced male rats.

PubMed

Fujiwara, Masaya; Chiba, Atsuhiko

2018-03-01

Sexual behavior is a natural reward that activates mesolimbic dopaminergic system. Microdialysis studies have shown that extracellular level of dopamine (DA) in the nucleus accumbens (NAcc) significantly increases during copulation in male rats. The NAcc DA level is also known to be increased during the presentation of a sexually receptive female before mating. This rise in DA was probably associated with sexual motivation elicited by incentive stimuli from the receptive female. These microdialysis studies, however, did not thoroughly investigated if olfactory stimuli from estrous females could significantly increase the extracellular DA in the NAcc of male rats. The present study was designed to examine systematically the relationship between the expression of preference for the olfactory stimuli from estrous females and the effects of these stimuli on the extracellular DA levels in the NAcc measured by in vivo microdialysis in male Long-Evans (LE) rats. We used two types of olfactory stimuli, either airborne odors (volatile stimuli) or soiled bedding (volatile plus nonvolatile stimuli). The sexually experienced male rats, which experienced six ejaculations, significantly preferred both of these olfactory stimuli from estrous females as opposed to males. Exposure to these female olfactory stimuli gradually increased extracellular DA in the NAcc, which reached significantly higher level above baseline during the period following the removal of the stimuli although not during the 15-min stimulus presentation period. The sexually naïve male rats, on the other hand, showed neither preference for olfactory stimuli from estrous females nor increase in the NAcc DA after exposure to these stimuli. These data suggest that in male LE rats olfactory stimuli from estrous females in and of themselves can be conditional cues that induce both incentive motivation and a significant increase in the NAcc DA probably as a result of being associated with sexual reward through copulatory experience. Copyright © 2017. Published by Elsevier Inc.

Opioid Modulation of Fos Protein Expression and Olfactory Circuitry Plays a Pivotal Role in What Neonates Remember

ERIC Educational Resources Information Center

Roth, Tania L.; Moriceau, Stephanie; Sullivan, Regina M.

2006-01-01

Paradoxically, fear conditioning (odor-0.5 mA shock) yields a learned odor preference in the neonate, presumably due to a unique learning and memory circuit that does not include apparent amygdala participation. Post-training opioid antagonism with naltrexone (NTX) blocks consolidation of this odor preference and instead yields memory of a learned…

Possible link between Toxoplasma gondii and the anosmia associated with neurodegenerative diseases.

PubMed

Prandota, Joseph

2014-05-01

Toxoplasma gondii is an intracellular protozoan infecting 30% to 50% of global human population. Recently, it was suggested that chronic latent neuroinflammation caused by the parasite may be responsible for the development of several neurodegenerative diseases manifesting with the loss of smell. Studies in animals inoculated with the parasite revealed cysts in various regions of the brain, including olfactory bulb. Development of behavioral changes was paralleled by the preferential persistence of cysts in defined anatomic structures of the brain, depending on the host, strain of the parasite, its virulence, and route of inoculation. Olfactory dysfunction reported in Alzheimer's disease, multiple sclerosis, and schizophrenia was frequently associated with the significantly increased serum anti-T gondii immunoglobulin G antibody levels. Damage of the olfactory system may be also at least in part responsible for the development of depression because T gondii infection worsened mood in such patients, and the olfactory bulbectomized rat serves as a model of depression.

Bee visitation rates to cultivated sunflowers increase with the amount and accessibility of nectar sugars

USDA-ARS?s Scientific Manuscript database

Pollinators make foraging decisions based on numerous floral traits, including nectar and pollen rewards, and associated visual and olfactory cues. For insect-pollinated crops, identifying and breeding for attractive floral traits may increase yields. In this study, we examined floral trait variatio...

Clinical and histologic studies of olfactory outcomes after nasoseptal flap harvesting.

PubMed

Kim, Sang-Wook; Park, Kyung Bum; Khalmuratova, Roza; Lee, Hong-Kyoung; Jeon, Sea-Yuong; Kim, Dae Woo

2013-07-01

Since the introduction of an endonasal endoscopic approach in transsphenoidal pituitary surgery, reports of perioperative olfactory changes have presented conflicting results. We examined the incidence of olfactory loss in cases of endoscopic transsphenoidal pituitary surgery with skull base repair using the nasoseptal flap (NSF) and the effects of monopolar electrocautery commonly used in designing the NSF. Case-control study. Fifteen patients who underwent endoscopic transsphenoidal pituitary surgery with skull base reconstruction using the NSF were divided into cold knife (n = 8) and electrocautery (n = 7) groups according to the device used in the superior incision of the NSF. Patients were followed regularly to monitor the need for dressing or adhesiolysis around the olfactory cleft. All subjects received olfactory tests before and 6 months after surgery. Septal mucosa specimens obtained during posterior septectomy were incised with different devices, and the degree of mucosal damage was evaluated. One patient in the electrocautery group demonstrated olfactory dysfunction postoperatively, but the other 14 patients showed no decrease in olfaction. In histologic analyses, 55.8% and 76.9% of the mucosal surface showed total epithelial loss when the mucosa was cut with cutting- and coagulation-mode electrocautery, respectively. In contrast, only 20% of the mucosal surface exhibited total epithelial loss when the mucosa was cut with a cold knife (P < .01). Olfactory impairment is not common after use of the NSF. Use of the cold knife in making superior incision may reduce tissue damage with better olfactory outcomes. Copyright © 2013 The American Laryngological, Rhinological and Otological Society, Inc.

Low plasma tryptophan is associated with olfactory function in healthy elderly community dwellers in Japan.

PubMed

Adachi, Yusuke; Shimodaira, Yoshiki; Nakamura, Hidehiro; Imaizumi, Akira; Mori, Maiko; Kageyama, Yoko; Noguchi, Yasushi; Seki, Asuka; Okabe, Yuki; Miyake, Yuko; Ono, Kaori; Kumagai, Shu

2017-10-16

Decreased circulating tryptophan (Trp) levels are frequently observed in elderly patients with neurodegenerative disease including Alzheimer's disease. Trp may serve as a potential biomarker for monitoring disease risk in elderly people. We aimed to investigate the association between low plasma Trp levels and olfactory function, which is known to predict age-related diseases including dementia in elderly people. A total of 144 healthy elderly Japanese community (≥ 65 years old) dwellers from the Health, Aging and Nutritional Improvement study (HANI study) were the subjects of our analysis. Low Trp levels were classified using the lower limit values of the reference interval according to a previous report. Olfactory function was assessed using a card-type test called Open Essence, which includes 12 odour items that are familiar to Japanese people. The elderly subjects with low circulating Trp levels were compared to a control group with normal plasma Trp levels. We conducted the analyses using 144 people aged 65 years or older (mean age 73.7 ± 5.5 years; 36.1% men). The subjects showed normal serum albumin levels (4.4 ± 0.2 g/dL) and no daily living disabilities. Low plasma Trp levels (low Trp group) were found in 11.1% of the study population. The low Trp group showed a significantly lower correct-answer rate for the items india ink, perfume, curry and sweaty smelling socks than control group (P < 0.05). There was also a significant association between low Trp levels and low olfactory ability, after adjusting for age and sex. Lower plasma Trp levels were associated with a decrease in olfactory function in functionally competent older individuals. Because olfactory dysfunction predicts age-related diseases, low plasma Trp levels may represent a clinical sign of disease risk in elderly people.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans.

PubMed

Green, Patrick A; Van Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-12-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. © 2012 The Authors. Journal of Anatomy © 2012 Anatomical Society.

Respiratory and olfactory turbinal size in canid and arctoid carnivorans

PubMed Central

Green, Patrick A; Valkenburgh, Blaire; Pang, Benison; Bird, Deborah; Rowe, Timothy; Curtis, Abigail

2012-01-01

Within the nasal cavity of mammals is a complex scaffold of paper-thin bones that function in respiration and olfaction. Known as turbinals, the bones greatly enlarge the surface area available for conditioning inspired air, reducing water loss, and improving olfaction. Given their functional significance, the relative development of turbinal bones might be expected to differ among species with distinct olfactory, thermoregulatory and/or water conservation requirements. Here we explore the surface area of olfactory and respiratory turbinals relative to latitude and diet in terrestrial Caniformia, a group that includes the canid and arctoid carnivorans (mustelids, ursids, procyonids, mephitids, ailurids). Using high-resolution computed tomography x-ray scans, we estimated respiratory and olfactory turbinal surface area and nasal chamber volume from three-dimensional virtual models of skulls. Across the Caniformia, respiratory surface area scaled isometrically with estimates of body size and there was no significant association with climate, as estimated by latitude. Nevertheless, one-on-one comparisons of sister taxa suggest that arctic species may have expanded respiratory turbinals. Olfactory surface area scaled isometrically among arctoids, but showed positive allometry in canids, reflecting the fact that larger canids, all of which are carnivorous, had relatively greater olfactory surface areas. In addition, among the arctoids, large carnivorous species such as the polar bear (Ursus maritimus) and wolverine (Gulo gulo) also displayed enlarged olfactory turbinals. More omnivorous caniform species that feed on substantial quantities of non-vertebrate foods had less expansive olfactory turbinals. Because large carnivorous species hunt widely dispersed prey, an expanded olfactory turbinal surface area may improve a carnivore's ability to detect prey over great distances using olfactory cues. PMID:23035637

FoxP2 and olfaction: divergence of FoxP2 expression in olfactory tubercle between different feeding habit bats.

PubMed

Chen, Qi; Wang, Lina; Jones, G; Metzner, W; Xuan, F J; Yin, Jiangxia; Sun, Y

2013-12-01

FoxP2 is a member of the winged helix/forkhead class of transcription factors. Despite FoxP2 is found to have particular relevance to speech and language, the role of this gene is broader and not yet fully elucidated. In this study, we investigated the expression of FoxP2 in the brains of bats with different feeding habits (two frugivorous species and three insectivorous species). We found FoxP2 expression in the olfactory tubercle of frugivorous species is significantly higher than that in insectivorous species. Difference of FoxP2 expression was not observed within each of the frugivorous or insectivorous group. The diverse expression patterns in olfactory tubercle between two kinds of bats indicate FoxP2 has a close relation with olfactory tubercle associated functions, suggesting its important role in sensory integration within the olfactory tubercle and such a discrepancy of FoxP2 expression in olfactory tubercle may take responsibility for the different feeding behaviors of frugivorous and insectivorous bats.

Stable olfactory sensory neuron in vivo physiology during normal aging.

PubMed

Kass, Marley D; Czarnecki, Lindsey A; McGann, John P

2018-05-08

Normal aging is associated with a number of smell impairments that are paralleled by age-dependent changes in the peripheral olfactory system, including decreases in olfactory sensory neurons (OSNs) and in the regenerative capacity of the epithelium. Thus, an age-dependent degradation of sensory input to the brain is one proposed mechanism for the loss of olfactory function in older populations. Here, we tested this hypothesis by performing in vivo optical neurophysiology in 6-, 12-, 18-, and 24-month-old mice. We visualized odor-evoked neurotransmitter release from populations of OSNs into olfactory bulb glomeruli, and found that these sensory inputs are actually quite stable during normal aging. Specifically, the magnitude and number of odor-evoked glomerular responses were comparable across all ages, and there was no effect of age on the sensitivity of OSN responses to odors or on the neural discriminability of different sensory maps. These results suggest that the brain's olfactory bulbs do not receive deteriorated input during aging and that local bulbar circuitry might adapt to maintain stable nerve input. Copyright © 2018 Elsevier Inc. All rights reserved.

The Origin, Development and Molecular Diversity of Rodent Olfactory Bulb Glutamatergic Neurons Distinguished by Expression of Transcription Factor NeuroD1.

PubMed

Roybon, Laurent; Mastracci, Teresa L; Li, Joyce; Stott, Simon R W; Leiter, Andrew B; Sussel, Lori; Brundin, Patrik; Li, Jia-Yi

2015-01-01

Production of olfactory bulb neurons occurs continuously in the rodent brain. Little is known, however, about cellular diversity in the glutamatergic neuron subpopulation. In the central nervous system, the basic helix-loop-helix transcription factor NeuroD1 (ND1) is commonly associated with glutamatergic neuron development. In this study, we utilized ND1 to identify the different subpopulations of olfactory bulb glutamategic neurons and their progenitors, both in the embryo and postnatally. Using knock-in mice, transgenic mice and retroviral transgene delivery, we demonstrate the existence of several different populations of glutamatergic olfactory bulb neurons, the progenitors of which are ND1+ and ND1- lineage-restricted, and are temporally and regionally separated. We show that the first olfactory bulb glutamatergic neurons produced - the mitral cells - can be divided into molecularly diverse subpopulations. Our findings illustrate the complexity of neuronal diversity in the olfactory bulb and that seemingly homogenous neuronal populations can consist of multiple subpopulations with unique molecular signatures of transcription factors and expressing neuronal subtype-specific markers.

Nanovesicle-based bioelectronic nose platform mimicking human olfactory signal transduction.

PubMed

Jin, Hye Jun; Lee, Sang Hun; Kim, Tae Hyun; Park, Juhun; Song, Hyun Seok; Park, Tai Hyun; Hong, Seunghun

2012-05-15

We developed a nanovesicle-based bioelectronic nose (NBN) that could recognize a specific odorant and mimic the receptor-mediated signal transmission of human olfactory systems. To build an NBN, we combined a single-walled carbon nanotube-based field effect transistor with cell-derived nanovesicles containing human olfactory receptors and calcium ion signal pathways. Importantly, the NBN took advantages of cell signal pathways for sensing signal amplification, enabling ≈ 100 times better sensitivity than that of previous bioelectronic noses based on only olfactory receptor protein and carbon nanotube transistors. The NBN sensors exhibited a human-like selectivity with single-carbon-atomic resolution and a high sensitivity of 1 fM detection limit. Moreover, this sensor platform could mimic a receptor-meditated cellular signal transmission in live cells. This sensor platform can be utilized for the study of molecular recognition and biological processes occurring at cell membranes and also for various practical applications such as food screening and medical diagnostics. Copyright © 2012 Elsevier B.V. All rights reserved.

Cigarette Smoke Delays Regeneration of the Olfactory Epithelium in Mice.

PubMed

Ueha, Rumi; Ueha, Satoshi; Sakamoto, Takashi; Kanaya, Kaori; Suzukawa, Keigo; Nishijima, Hironobu; Kikuta, Shu; Kondo, Kenji; Matsushima, Kouji; Yamasoba, Tatsuya

2016-08-01

The olfactory system is a unique part of the mammalian nervous system due to its capacity for neurogenesis and the replacement of degenerating receptor neurons. Cigarette smoking is a major cause of olfactory dysfunction. However, the mechanisms by which cigarette smoke impairs the regenerative olfactory receptor neurons (ORNs) remain unclear. Here, we investigated the influence of cigarette smoke on ORN regeneration following methimazole-induced ORN injury. Administration of methimazole caused detachment of the olfactory epithelium from the basement membrane and induced olfactory dysfunction, thus enabling us to analyze the process of ORN regeneration. We found that intranasal administration of cigarette smoke solution (CSS) suppressed the recovery of ORNs and olfaction following ORN injury. Defective ORN recovery in CSS-treated mice was not associated with any change in the number of SOX2(+) ORN progenitor cells in the basal layer of the OE, but was associated with impaired recovery of GAP43(+) immature ORNs. In the nasal mucosa, mRNA expression levels of neurotrophic factors such as brain-derived neurotrophic factor, neurotrophin-3, neurotrophin-5, glial cell-derived neurotrophic factor, and insulin-like growth factor-1 (IGF-1) were increased following OE injury, whereas CSS administration decreased the ORN injury-induced IGF-1 expression. Administration of recombinant human IGF-1 prevented the CSS-induced suppression of ORN recovery following injury. These results suggest that CSS impairs regeneration of ORNs by suppressing the development of immature ORNs from ORN progenitors, at least partly by reducing IGF-1 in the nasal mucosa.

Olfactory imprinting is correlated with changes in gene expression in the olfactory epithelia of the zebrafish.

PubMed

Harden, Maegan V; Newton, Lucy A; Lloyd, Russell C; Whitlock, Kathleen E

2006-11-01

Odors experienced as juveniles can have significant effects on the behavior of mature organisms. A dramatic example of this occurs in salmon, where the odors experienced by developing fish determine the river to which they return as adults. Further examples of olfactory memories are found in many animals including vertebrates and invertebrates. Yet, the cellular and molecular bases underlying the formation of olfactory memory are poorly understood. We have devised a series of experiments to determine whether zebrafish can form olfactory memories much like those observed in salmonids. Here we show for the first time that zebrafish form and retain olfactory memories of an artificial odorant, phenylethyl alcohol (PEA), experienced as juveniles. Furthermore, we demonstrate that exposure to PEA results in changes in gene expression within the olfactory sensory system. These changes are evident by in situ hybridization in the olfactory epithelium of the developing zebrafish. Strikingly, our analysis by in situ hybridization demonstrates that the transcription factor, otx2, is up regulated in the olfactory sensory epithelia in response to PEA. This increase is evident at 2-3 days postfertilization and is maintained in the adult animals. We propose that the changes in otx2 gene expression are manifest as an increase in the number of neuronal precursors in the cells olfactory epithelium of the odor-exposed fish. Thus, our results reveal a role for the environment in controlling gene expression in the developing peripheral nervous system. Copyright 2006 Wiley Periodicals, Inc.

Genotypic Influence on Aversive Conditioning in Honeybees, Using a Novel Thermal Reinforcement Procedure

PubMed Central

Junca, Pierre; Carcaud, Julie; Moulin, Sibyle; Garnery, Lionel; Sandoz, Jean-Christophe

2014-01-01

In Pavlovian conditioning, animals learn to associate initially neutral stimuli with positive or negative outcomes, leading to appetitive and aversive learning respectively. The honeybee (Apis mellifera) is a prominent invertebrate model for studying both versions of olfactory learning and for unraveling the influence of genotype. As a queen bee mates with about 15 males, her worker offspring belong to as many, genetically-different patrilines. While the genetic dependency of appetitive learning is well established in bees, it is not the case for aversive learning, as a robust protocol was only developed recently. In the original conditioning of the sting extension response (SER), bees learn to associate an odor (conditioned stimulus - CS) with an electric shock (unconditioned stimulus - US). This US is however not a natural stimulus for bees, which may represent a potential caveat for dissecting the genetics underlying aversive learning. We thus first tested heat as a potential new US for SER conditioning. We show that thermal stimulation of several sensory structures on the bee’s body triggers the SER, in a temperature-dependent manner. Moreover, heat applied to the antennae, mouthparts or legs is an efficient US for SER conditioning. Then, using microsatellite analysis, we analyzed heat sensitivity and aversive learning performances in ten worker patrilines issued from a naturally inseminated queen. We demonstrate a strong influence of genotype on aversive learning, possibly indicating the existence of a genetic determinism of this capacity. Such determinism could be instrumental for efficient task partitioning within the hive. PMID:24828422

On the olfactory anatomy in an archaic whale (Protocetidae, Cetacea) and the minke whale Balaenoptera acutorostrata (Balaenopteridae, Cetacea).

PubMed

Godfrey, Stephen J; Geisler, Jonathan; Fitzgerald, Erich M G

2013-02-01

The structure of the olfactory apparatus is not well known in both archaic and extant whales; the result of poor preservation in most fossils and locational isolation deep within the skulls in both fossil and Recent taxa. Several specimens now shed additional light on the subject. A partial skull of an archaic cetacean is reported from the Pamunkey River, Virginia, USA. The specimen probably derives from the upper middle Eocene (Piney Point Formation) and is tentatively assigned to the Protocetidae. Uncrushed cranial cavities associated with the olfactory apparatus were devoid of sediment. CT scans clearly reveal the dorsal nasal meatus, ethmoturbinates within the olfactory recess, the cribriform plate, the area occupied by the olfactory bulbs, and the olfactory nerve tract. Several sectioned skulls of the minke whale (Balaenoptera acutorostrata) were also examined, and olfactory structures are remarkably similar to those observed in the fossil skull from the Pamunkey River. One important difference between the two is that the fossil specimen has an elongate olfactory nerve tract. The more forward position of the external nares in extant balaenopterids when compared with those of extant odontocetes is interpreted to be the result of the need to retain a functional olfactory apparatus and the forward position of the supraoccipital/cranial vertex. An increase in the distance between the occipital condyles and the vertex in balaenopterids enhances the mechanical advantage of the epaxial musculature that inserts on the occiput, a specialization that likely stabilizes the head of these enormous mammals during lunge feeding. Copyright © 2012 Wiley Periodicals, Inc.

Parallel processing via a dual olfactory pathway in the honeybee.

PubMed

Brill, Martin F; Rosenbaum, Tobias; Reus, Isabelle; Kleineidam, Christoph J; Nawrot, Martin P; Rössler, Wolfgang

2013-02-06

In their natural environment, animals face complex and highly dynamic olfactory input. Thus vertebrates as well as invertebrates require fast and reliable processing of olfactory information. Parallel processing has been shown to improve processing speed and power in other sensory systems and is characterized by extraction of different stimulus parameters along parallel sensory information streams. Honeybees possess an elaborate olfactory system with unique neuronal architecture: a dual olfactory pathway comprising a medial projection-neuron (PN) antennal lobe (AL) protocerebral output tract (m-APT) and a lateral PN AL output tract (l-APT) connecting the olfactory lobes with higher-order brain centers. We asked whether this neuronal architecture serves parallel processing and employed a novel technique for simultaneous multiunit recordings from both tracts. The results revealed response profiles from a high number of PNs of both tracts to floral, pheromonal, and biologically relevant odor mixtures tested over multiple trials. PNs from both tracts responded to all tested odors, but with different characteristics indicating parallel processing of similar odors. Both PN tracts were activated by widely overlapping response profiles, which is a requirement for parallel processing. The l-APT PNs had broad response profiles suggesting generalized coding properties, whereas the responses of m-APT PNs were comparatively weaker and less frequent, indicating higher odor specificity. Comparison of response latencies within and across tracts revealed odor-dependent latencies. We suggest that parallel processing via the honeybee dual olfactory pathway provides enhanced odor processing capabilities serving sophisticated odor perception and olfactory demands associated with a complex olfactory world of this social insect.

Odor Experiences during Preimaginal Stages Cause Behavioral and Neural Plasticity in Adult Honeybees

PubMed Central

Ramírez, Gabriela; Fagundez, Carol; Grosso, Juan P.; Argibay, Pablo; Arenas, Andrés; Farina, Walter M.

2016-01-01

In eusocial insects, experiences acquired during the development have long-term consequences on mature behavior. In the honeybee that suffers profound changes associated with metamorphosis, the effect of odor experiences at larval instars on the subsequent physiological and behavioral response is still unclear. To address the impact of preimaginal experiences on the adult honeybee, colonies containing larvae were fed scented food. The effect of the preimaginal experiences with the food odor was assessed in learning performance, memory retention and generalization in 3–5- and 17–19 day-old bees, in the regulation of their expression of synaptic-related genes and in the perception and morphology of their antennae. Three-five day old bees that experienced 1-hexanol (1-HEX) as food scent responded more to the presentation of the odor during the 1-HEX conditioning than control bees (i.e., bees reared in colonies fed unscented food). Higher levels of proboscis extension response (PER) to 1-HEX in this group also extended to HEXA, the most perceptually similar odor to the experienced one that we tested. These results were not observed for the group tested at older ages. In the brain of young adults, larval experiences triggered similar levels of neurexins (NRXs) and neuroligins (Nlgs) expression, two proteins that have been involved in synaptic formation after associative learning. At the sensory periphery, the experience did not alter the number of the olfactory sensilla placoidea, but did reduce the electrical response of the antennae to the experienced and novel odor. Our study provides a new insight into the effects of preimaginal experiences in the honeybee and the mechanisms underlying olfactory plasticity at larval stage of holometabolous insects. PMID:27375445

Odor Experiences during Preimaginal Stages Cause Behavioral and Neural Plasticity in Adult Honeybees.

PubMed

Ramírez, Gabriela; Fagundez, Carol; Grosso, Juan P; Argibay, Pablo; Arenas, Andrés; Farina, Walter M

2016-01-01

In eusocial insects, experiences acquired during the development have long-term consequences on mature behavior. In the honeybee that suffers profound changes associated with metamorphosis, the effect of odor experiences at larval instars on the subsequent physiological and behavioral response is still unclear. To address the impact of preimaginal experiences on the adult honeybee, colonies containing larvae were fed scented food. The effect of the preimaginal experiences with the food odor was assessed in learning performance, memory retention and generalization in 3-5- and 17-19 day-old bees, in the regulation of their expression of synaptic-related genes and in the perception and morphology of their antennae. Three-five day old bees that experienced 1-hexanol (1-HEX) as food scent responded more to the presentation of the odor during the 1-HEX conditioning than control bees (i.e., bees reared in colonies fed unscented food). Higher levels of proboscis extension response (PER) to 1-HEX in this group also extended to HEXA, the most perceptually similar odor to the experienced one that we tested. These results were not observed for the group tested at older ages. In the brain of young adults, larval experiences triggered similar levels of neurexins (NRXs) and neuroligins (Nlgs) expression, two proteins that have been involved in synaptic formation after associative learning. At the sensory periphery, the experience did not alter the number of the olfactory sensilla placoidea, but did reduce the electrical response of the antennae to the experienced and novel odor. Our study provides a new insight into the effects of preimaginal experiences in the honeybee and the mechanisms underlying olfactory plasticity at larval stage of holometabolous insects.

Morphological study on the olfactory systems of the snapping turtle, Chelydra serpentina.

PubMed

Nakamuta, Nobuaki; Nakamuta, Shoko; Kato, Hideaki; Yamamoto, Yoshio

2016-06-01

In this study, the olfactory system of a semi-aquatic turtle, the snapping turtle, has been morphologically investigated by electron microscopy, immunohistochemistry, and lectin histochemistry. The nasal cavity of snapping turtle was divided into the upper and lower chambers, lined by the sensory epithelium containing ciliated and non-ciliated olfactory receptor neurons, respectively. Each neuron expressed both Gαolf, the α-subunit of G-proteins coupling to the odorant receptors, and Gαo, the α-subunit of G-proteins coupling to the type 2 vomeronasal receptors. The axons originating from the upper chamber epithelium projected to the ventral part of the olfactory bulb, while those from the lower chamber epithelium to the dorsal part of the olfactory bulb. Despite the identical expression of G-protein α-subunits in the olfactory receptor neurons, these two projections were clearly distinguished from each other by the differential expression of glycoconjugates. In conclusion, these data indicate the presence of two types of olfactory systems in the snapping turtle. Topographic arrangement of the upper and lower chambers and lack of the associated glands in the lower chamber epithelium suggest their possible involvement in the detection of odorants: upper chamber epithelium in the air and the lower chamber epithelium in the water. Copyright © 2016 Elsevier Ltd. All rights reserved.

Alterations of brain grey matter density and olfactory bulb volume in patients with olfactory loss after traumatic brain injury.

PubMed

Han, Pengfei; Winkler, Nicole; Hummel, Cornelia; Hähner, Antje; Gerber, Johannes; Hummel, Thomas

2018-04-27

Olfactory loss and traumatic brain injury (TBI) both lead to anatomical brain alterations in humans. Little research has been done on the structural brain changes for TBI patients with olfactory loss. Using voxel-based morphometry, the grey matter (GM) density was examined for twenty-two TBI patients with hyposmia, twenty-four TBI patients with anosmia, and twenty-two age-matched controls. Olfactory bulb (OB) volumes were measured by manual segmentation of acquired T2 weighted coronal slices using a standardized protocol. Brain lesions in the olfactory relevant areas were also examined for TBI patients. Results showed that patients with anosmia have more frequent lesions in the OB, orbitofrontal cortex (OFC) and the temporal lobe pole, as compared to patients with hyposmia. GM density in the primary olfactory area was decreased in both groups of patients. In addition, compared to controls, patients with anosmia showed GM density reduction in several secondary olfactory eloquent regions, including the gyrus rectus, medial OFC, anterior cingulate cortex, insula, and cerebellum. However, patients with hyposmia showed a lesser degree of GM reduction compared to healthy controls. Smaller OB volumes were found for patients with olfactory loss as compared to controls. TBI patients with anosmia had the smallest OB volumes which were caused by the lesions for OB. In addition, post-TBI duration was negatively correlated with GM density in the secondary olfactory areas in patients with hyposmia, but was positively correlated with GM density in the frontal and temporal gyrus in patients with anosmia. The GM density and OB volume reduction among TBI patients with olfactory loss was largely depend on the location and severity of brain lesions in olfactory relevant regions. Longer post-TBI duration had an impact on brain GM density changes, which indicate a decreased olfactory function in patients with hyposmia and possible compensatory mechanisms in patients with anosmia.

Parasites and a host's sense of smell: reduced chemosensory performance of fathead minnows (Pimephales promelas) infected with a monogenean parasite.

PubMed

Lari, Ebrahim; Goater, Cameron P; Cone, David K; Pyle, Greg G

2017-05-01

Parasites residing within the central nervous system of their hosts have the potential to reduce various components of host performance, but such effects are rarely evaluated. We assessed the olfactory acuity of fathead minnows (Pimephales promelas) infected experimentally with the monogenean Dactylogyrus olfactorius, the adults of which live within the host's olfactory chambers. Olfactory acuity was compared between infected and uninfected hosts by assessing electro-olfactography (EOG) neural responses to chemical stimuli that indicate the presence of food (L-alanine) or the presence of conspecifics (taurocholic acid). We also compared differences in gross morphology of the olfactory epithelium in infected and uninfected minnows. Differences in EOG responses between infected and uninfected minnows to both cue types were non-significant at 30 days post-exposure. By days 60 and 90, coincident with a two times increase in parasite intensity in the olfactory chambers, the EOG responses of infected minnows were 70-90% lower than controls. When infected fish were treated with a parasiticide (Prazipro), olfactory acuity returned to control levels by day 7 post-treatment. The observed reduction in olfactory acuity is best explained by the reduced density of cilia covering the olfactory chambers of infected fish, or by the concomitant increase in the density of mucous cells that cover the olfactory chambers. These morphological changes are likely due to the direct effects of attachment and feeding by individual worms or by indirect effects associated with host responses. Our results show that infection of a commonly occurring monogenean in fathead minnows reduces olfactory acuity. Parasite-induced interference with olfactory performance may reduce a fish's ability to detect, or respond to, chemical cues originating from food, predators, competitors or mates. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

An olfactory demography of a diverse metropolitan population.

PubMed

Keller, Andreas; Hempstead, Margaret; Gomez, Iran A; Gilbert, Avery N; Vosshall, Leslie B

2012-10-10

Human perception of the odour environment is highly variable. People vary both in their general olfactory acuity as well as in if and how they perceive specific odours. In recent years, it has been shown that genetic differences contribute to variability in both general olfactory acuity and the perception of specific odours. Odour perception also depends on other factors such as age and gender. Here we investigate the influence of these factors on both general olfactory acuity and on the perception of 66 structurally and perceptually different odours in a diverse subject population. We carried out a large human olfactory psychophysics study of 391 adult subjects in metropolitan New York City, an ethnically and culturally diverse North American metropolis. 210 of the subjects were women and the median age was 34.6 years (range 19-75). We recorded ~2,300 data points per subject to obtain a comprehensive perceptual phenotype, comprising multiple perceptual measures of 66 diverse odours. We show that general olfactory acuity correlates with gender, age, race, smoking habits, and body type. Young, female, non-smoking subjects had the highest average olfactory acuity. Deviations from normal body type in either direction were associated with decreased olfactory acuity. Beyond these factors we also show that, surprisingly, there are many odour-specific influences of race, age, and gender on olfactory perception. We show over 100 instances in which the intensity or pleasantness perception of an odour is significantly different between two demographic groups. These data provide a comprehensive snapshot of the olfactory sense of a diverse population. Olfactory acuity in the population is most strongly influenced by age, followed by gender. We also show a large number of diverse correlations between demographic factors and the perception of individual odours that may reflect genetic differences as well as different prior experiences with these odours between demographic groups.

An olfactory demography of a diverse metropolitan population

PubMed Central

2012-01-01

Background Human perception of the odour environment is highly variable. People vary both in their general olfactory acuity as well as in if and how they perceive specific odours. In recent years, it has been shown that genetic differences contribute to variability in both general olfactory acuity and the perception of specific odours. Odour perception also depends on other factors such as age and gender. Here we investigate the influence of these factors on both general olfactory acuity and on the perception of 66 structurally and perceptually different odours in a diverse subject population. Results We carried out a large human olfactory psychophysics study of 391 adult subjects in metropolitan New York City, an ethnically and culturally diverse North American metropolis. 210 of the subjects were women and the median age was 34.6 years (range 19–75). We recorded ~2,300 data points per subject to obtain a comprehensive perceptual phenotype, comprising multiple perceptual measures of 66 diverse odours. We show that general olfactory acuity correlates with gender, age, race, smoking habits, and body type. Young, female, non-smoking subjects had the highest average olfactory acuity. Deviations from normal body type in either direction were associated with decreased olfactory acuity. Beyond these factors we also show that, surprisingly, there are many odour-specific influences of race, age, and gender on olfactory perception. We show over 100 instances in which the intensity or pleasantness perception of an odour is significantly different between two demographic groups. Conclusions These data provide a comprehensive snapshot of the olfactory sense of a diverse population. Olfactory acuity in the population is most strongly influenced by age, followed by gender. We also show a large number of diverse correlations between demographic factors and the perception of individual odours that may reflect genetic differences as well as different prior experiences with these odours between demographic groups. PMID:23046643

Gray Matter Volume Reduction of Olfactory Cortices in Patients With Idiopathic Olfactory Loss

PubMed Central

Yao, Linyin; Pinto, Jayant Marian; Yi, Xiaoli; Li, Li; Peng, Peng

2014-01-01

Idiopathic olfactory loss (IOL) is a common olfactory disorder. Little is known about the pathophysiology of this disease. Previous studies demonstrated decreased olfactory bulb (OB) volume in IOL patients when compared with controls. The aim of our study was to investigate structural brain alterations in areas beyond the OB. We acquired T1-weighted magnetic resonance images from 16 patients with IOL and from 16 age- and sex-matched controls on a 3T scanner. Voxel-based morphometry (VBM) was performed using VBM8 toolbox and SPM8 in a Matlab environment. Psychophysical testing confirmed that patients had higher scores for Toyota and Takagi olfactometer and lower scores for Sniffin’ Sticks olfactory test than controls (t = 46.9, P < 0.001 and t = 21.4, P < 0.001, respectively), consistent with olfactory dysfunction. There was a significant negative correlation between the 2 olfactory tests (r = −0.6, P = 0.01). In a volume of interest analysis including primary and secondary olfactory areas, we found patients with IOL to exhibit gray matter volume loss in the orbitofrontal cortex, anterior cingulate cortex, insular cortex, parahippocampal cortex, and the piriform cortex. The present study indicates that changes in the central brain structures proximal to the OB occur in IOL. Further investigations of this phenomenon may be helpful to elucidate the etiology of IOL. PMID:25240014

Odor preference and olfactory memory are impaired in Olfaxin-deficient mice.

PubMed

Islam, Saiful; Ueda, Masashi; Nishida, Emika; Wang, Miao-Xing; Osawa, Masatake; Lee, Dongsoo; Itoh, Masanori; Nakagawa, Kiyomi; Tana; Nakagawa, Toshiyuki

2018-06-01

Olfaxin, which is a BNIP2 and Cdc42GAP homology (BCH) domain-containing protein, is predominantly expressed in mitral and tufted (M/T) cells in the olfactory bulb (OB). Olfaxin and Caytaxin, which share 56.3% amino acid identity, are similar in their glutamatergic terminal localization, kidney-type glutaminase (KGA) interaction, and caspase-3 substrate. Although the deletion of Caytaxin protein causes human Cayman ataxia and ataxia in the mutant mouse, the function of Olfaxin is largely unknown. In this study, we generated Prune2 gene mutant mice (Prune2 Ex16-/- ; knock out [KO] mice) using the CRISPR/Cas9 system, during which the exon 16 containing start codon of Olfaxin mRNA was deleted. Exon 16 has 80 nucleotides and is contained in four of five Prune2 isoforms, including PRUNE2, BMCC1, BNIPXL, and Olfaxin/BMCC1s. The levels of Olfaxin mRNA and Olfaxin protein in the OB and piriform cortex of KO mice significantly decreased. Although Prune2 mRNA also significantly decreased in the spinal cord, the gross anatomy of the spinal cord and dorsal root ganglion (DRG) was intact. Further, disturbance of the sensory and motor system was not observed in KO mice. Therefore, in the current study, we examined the role of Olfaxin in the olfactory system where PRUNE2, BMCC1, and BNIPXL are scarcely expressed. Odor preference was impaired in KO mice using opposite-sex urinary scents as well as a non-social odor stimulus (almond). Results of the odor-aversion test demonstrated that odor-associative learning was disrupted in KO mice. Moreover, the NMDAR2A/NMDAR2B subunits switch in the piriform cortex was not observed in KO mice. These results indicated that Olfaxin may play a critical role in odor preference and olfactory memory. Copyright © 2018 Elsevier B.V. All rights reserved.

Relative vascular permeability and vascularity across different regions of the rat nasal mucosa: implications for nasal physiology and drug delivery

PubMed Central

Kumar, Niyanta N.; Gautam, Mohan; Lochhead, Jeffrey J.; Wolak, Daniel J.; Ithapu, Vamsi; Singh, Vikas; Thorne, Robert G.

2016-01-01

Intranasal administration provides a non-invasive drug delivery route that has been proposed to target macromolecules either to the brain via direct extracellular cranial nerve-associated pathways or to the periphery via absorption into the systemic circulation. Delivering drugs to nasal regions that have lower vascular density and/or permeability may allow more drug to access the extracellular cranial nerve-associated pathways and therefore favor delivery to the brain. However, relative vascular permeabilities of the different nasal mucosal sites have not yet been reported. Here, we determined that the relative capillary permeability to hydrophilic macromolecule tracers is significantly greater in nasal respiratory regions than in olfactory regions. Mean capillary density in the nasal mucosa was also approximately 5-fold higher in nasal respiratory regions than in olfactory regions. Applying capillary pore theory and normalization to our permeability data yielded mean pore diameter estimates ranging from 13–17 nm for the nasal respiratory vasculature compared to <10 nm for the vasculature in olfactory regions. The results suggest lymphatic drainage for CNS immune responses may be favored in olfactory regions due to relatively lower clearance to the bloodstream. Lower blood clearance may also provide a reason to target the olfactory area for drug delivery to the brain. PMID:27558973

Olfactory-visual integration facilitates perception of subthreshold negative emotion.

PubMed

Novak, Lucas R; Gitelman, Darren R; Schuyler, Brianna; Li, Wen

2015-10-01

A fast growing literature of multisensory emotion integration notwithstanding, the chemical senses, intimately associated with emotion, have been largely overlooked. Moreover, an ecologically highly relevant principle of "inverse effectiveness", rendering maximal integration efficacy with impoverished sensory input, remains to be assessed in emotion integration. Presenting minute, subthreshold negative (vs. neutral) cues in faces and odors, we demonstrated olfactory-visual emotion integration in improved emotion detection (especially among individuals with weaker perception of unimodal negative cues) and response enhancement in the amygdala. Moreover, while perceptual gain for visual negative emotion involved the posterior superior temporal sulcus/pSTS, perceptual gain for olfactory negative emotion engaged both the associative olfactory (orbitofrontal) cortex and amygdala. Dynamic causal modeling (DCM) analysis of fMRI timeseries further revealed connectivity strengthening among these areas during crossmodal emotion integration. That multisensory (but not low-level unisensory) areas exhibited both enhanced response and region-to-region coupling favors a top-down (vs. bottom-up) account for olfactory-visual emotion integration. Current findings thus confirm the involvement of multisensory convergence areas, while highlighting unique characteristics of olfaction-related integration. Furthermore, successful crossmodal binding of subthreshold aversive cues not only supports the principle of "inverse effectiveness" in emotion integration but also accentuates the automatic, unconscious quality of crossmodal emotion synthesis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Olfactory Proteins Mediating Chemical Communication in the Navel Orangeworm Moth, Amyelois transitella

PubMed Central

Leal, Walter S.; Ishida, Yuko; Pelletier, Julien; Xu, Wei; Rayo, Josep; Xu, Xianzhong; Ames, James B.

2009-01-01

Background The navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae), is the most serious insect pest of almonds and pistachios in California for which environmentally friendly alternative methods of control — like pheromone-based approaches — are highly desirable. Some constituents of the sex pheromone are unstable and could be replaced with parapheromones, which may be designed on the basis of molecular interaction of pheromones and pheromone-detecting olfactory proteins. Methodology By analyzing extracts from olfactory and non-olfactory tissues, we identified putative olfactory proteins, obtained their N-terminal amino acid sequences by Edman degradation, and used degenerate primers to clone the corresponding cDNAs by SMART RACE. Additionally, we used degenerate primers based on conserved sequences of known proteins to fish out other candidate olfactory genes. We expressed the gene encoding a newly identified pheromone-binding protein, which was analyzed by circular dichroism, fluorescence, and nuclear magnetic resonance, and used in a binding assay to assess affinity to pheromone components. Conclusion We have cloned nine cDNAs encoding olfactory proteins from the navel orangeworm, including two pheromone-binding proteins, two general odorant-binding proteins, one chemosensory protein, one glutathione S-transferase, one antennal binding protein X, one sensory neuron membrane protein, and one odorant receptor. Of these, AtraPBP1 is highly enriched in male antennae. Fluorescence, CD and NMR studies suggest a dramatic pH-dependent conformational change, with high affinity to pheromone constituents at neutral pH and no binding at low pH. PMID:19789654

[Organization of olfactory system of the Indian major carp Labeo rohita (Ham.): a study using scanning and transmission microscopy].

PubMed

Bhute, Y V; Baile, V V

2007-01-01

Catla catla, Labeo rohita, and Cirrhinus mrigala are important alimentary fish in India. Their reproduction (breeding) depends on season. The fish perceive external factors-stimuli and chemical signals through the olfactory system that plays the key role in the central regulation of reproduction. However, in the available literature, any electron microscopy data on organization of olfactory elements in these fish are absent. We have studied ultrastructure of the olfactory organ in male L. rohita by using scanning (SEM) and transmission electron microscopy (TEM). The olfactory organ consists of olfactory epithelium, a short nerve, and olfactory bulb. The organ has oval shape and consists of approximately 47-52 lamellae in adult fish and of 14-20 lamellae in fish at the stage of fingerling. These lamellae originate from the midline raphe. By using SEM, the presence of microvillar sensory and ciliated non-sensory cells in these lamellae is shown. By using TEM, a microvillar receptor cell is revealed, which has rough endoplasmic reticulum and Golgi apparatus towards the apical end. Basal cells are found at the base of the receptor cell; supporting cells are located adjacent to olfactory receptor neurons, while epithelial cells--in the non-sensory part of olfactory epithelium. Mast, blastema and macrophages cells are also found in the basal lamina. This work is the first publication on structural organization of olfactory system of the Indian major carp, which provides information about morphological and ultrastructural organization of olfactory system and opens new opportunities for study of chemical neuroanatomy, sensory signal processing, and nervous regulation of reproduction of the Indian major carp.

Context-dependent memory: colour versus odour.

PubMed

Pointer, S C; Bond, N W

1998-06-01

An olfactory stimulus and a visual stimulus were employed in a context-dependent memory study using a prose passage as the to-be-remembered item. Ninety-five university students (aged 17-35 years) learned the passage of prose in the presence of one of the stimuli and were then asked to recall the passage with the original context either reinstated or not reinstated. The results revealed a significant context-dependent memory effect for the olfactory cue but not for the visual cue. They demonstrate support for the effectiveness of odours as context cues and it is suggested that context-dependent memory processes may underlie the formation and retrieval of odour-evoked autobiographical memories.

Fetal alcohol exposure leads to abnormal olfactory bulb development and impaired odor discrimination in adult mice.

PubMed

Akers, Katherine G; Kushner, Steven A; Leslie, Ana T; Clarke, Laura; van der Kooy, Derek; Lerch, Jason P; Frankland, Paul W

2011-07-07

Children whose mothers consumed alcohol during pregnancy exhibit widespread brain abnormalities and a complex array of behavioral disturbances. Here, we used a mouse model of fetal alcohol exposure to investigate relationships between brain abnormalities and specific behavioral alterations during adulthood. Mice drank a 10% ethanol solution throughout pregnancy. When fetal alcohol-exposed offspring reached adulthood, we used high resolution MRI to conduct a brain-wide screen for structural changes and found that the largest reduction in volume occurred in the olfactory bulbs. Next, we tested adult mice in an associative olfactory task and found that fetal alcohol exposure impaired discrimination between similar odors but left odor memory intact. Finally, we investigated olfactory bulb neurogenesis as a potential mechanism by performing an in vitro neurosphere assay, in vivo labeling of new cells using BrdU, and in vivo labeling of new cells using a transgenic reporter system. We found that fetal alcohol exposure decreased the number of neural precursor cells in the subependymal zone and the number of new cells in the olfactory bulbs during the first few postnatal weeks. Using a combination of techniques, including structural brain imaging, in vitro and in vivo cell detection methods, and behavioral testing, we found that fetal alcohol exposure results in smaller olfactory bulbs and impairments in odor discrimination that persist into adulthood. Furthermore, we found that these abnormalities in olfactory bulb structure and function may arise from deficits in the generation of new olfactory bulb neurons during early postnatal development.

Identification of olfactory receptor genes in the Japanese grenadier anchovy Coilia nasus.

PubMed

Zhu, Guoli; Wang, Liangjiang; Tang, Wenqiao; Wang, Xiaomei; Wang, Cong

2017-01-01

Olfaction is essential for fish to detect odorant elements in the environment and plays a critical role in navigating, locating food and detecting predators. Olfactory function is produced by the olfactory transduction pathway and is activated by olfactory receptors (ORs) through the binding of odorant elements. Recently, four types of olfactory receptors have been identified in vertebrate olfactory epithelium, including main odorant receptors (MORs), vomeronasal type receptors (VRs), trace-amine associated receptors (TAARs) and formyl peptide receptors (FPRs). It has been hypothesized that migratory fish, which have the ability to perform spawning migration, use olfactory cues to return to natal rivers. Therefore, obtaining OR genes from migratory fish will provide a resource for the study of molecular mechanisms that underlie fish spawning migration behaviors. Previous studies of OR genes have mainly focused on genomic data, however little information has been gained at the transcript level. In this study, we identified the OR genes of an economically important commercial fish Coilia nasus through searching for olfactory epithelium transcriptomes. A total of 142 candidate MOR, 52 V2R/OlfC, 32 TAAR and two FPR putative genes were identified. In addition, through genomic analysis we identified several MOR genes containing introns, which is unusual for vertebrate MOR genes. The transcriptome-scale mining strategy proved to be fruitful in identifying large sets of OR genes from species whose genome information is unavailable. Our findings lay the foundation for further research into the possible molecular mechanisms underlying the spawning migration behavior in C. nasus .

Scents and Nonsense: Olfactory Dysfunction in Schizophrenia

PubMed Central

Turetsky, Bruce I.; Hahn, Chang-Gyu; Borgmann-Winter, Karin; Moberg, Paul J.

2009-01-01

Among the sensory modalities, olfaction is most closely associated with the frontal and temporal brain regions that are implicated in schizophrenia and most intimately related to the affective and mnemonic functions that these regions subserve. Olfactory probes may therefore be ideal tools through which to assess the structural and functional integrity of the neural substrates that underlie disease-related cognitive and emotional disturbances. Perhaps more importantly, to the extent that early sensory afferents are also disrupted in schizophrenia, the olfactory system—owing to its strategic anatomic location—may be especially vulnerable to such disruption. Olfactory dysfunction may therefore be a sensitive indicator of schizophrenia pathology and may even serve as an “early warning” sign of disease vulnerability or onset. In this article, we review the evidence supporting a primary olfactory sensory disturbance in schizophrenia. Convergent data indicate that structural and functional abnormalities extend from the cortex to the most peripheral elements of the olfactory system. These reflect, in part, a genetically mediated neurodevelopmental etiology. Gross structural and functional anomalies are mirrored by cellular and molecular abnormalities that suggest decreased or faulty innervation and/or dysregulation of intracellular signaling. A unifying mechanistic hypothesis may be the epigenetic regulation of gene expression. With the opportunity to obtain olfactory neural tissue from live patients through nasal epithelial biopsy, the peripheral olfactory system offers a uniquely accessible window through which the pathophysiological antecedents and sequelae of schizophrenia may be observed. This could help to clarify underlying brain mechanisms and facilitate identification of clinically relevant biomarkers. PMID:19793796

Associative Learning during Early Adulthood Enhances Later Memory Retention in Honeybees

PubMed Central

Arenas, Andrés; Fernández, Vanesa M.; Farina, Walter M.

2009-01-01

Background Cognitive experiences during the early stages of life play an important role in shaping the future behavior in mammals but also in insects, in which precocious learning can directly modify behaviors later in life depending on both the timing and the rearing environment. However, whether olfactory associative learning acquired early in the adult stage of insects affect memorizing of new learning events has not been studied yet. Methodology Groups of adult honeybee workers that experienced an odor paired with a sucrose solution 5 to 8 days or 9 to 12 days after emergence were previously exposed to (i) a rewarded experience through the offering of scented food, or (ii) a non-rewarded experience with a pure volatile compound in the rearing environment. Principal Findings Early rewarded experiences (either at 1–4 or 5–8 days of adult age) enhanced retention performance in 9–12-day-conditioned bees when they were tested at 17 days of age. The highest retention levels at this age, which could not be improved with prior rewarded experiences, were found for memories established at 5–8 days of adult age. Associative memories acquired at 9–12 days of age showed a weak effect on retention for some pure pre-exposed volatile compounds; whereas the sole exposure of an odor at any younger age did not promote long-term effects on learning performance. Conclusions The associative learning events that occurred a few days after adult emergence improved memorizing in middle-aged bees. In addition, both the timing and the nature of early sensory inputs interact to enhance retention of new learning events acquired later in life, an important matter in the social life of honeybees. PMID:19956575

Unilateral endonasal transcribriform approach with septal transposition for olfactory groove meningioma: can olfaction be preserved?

PubMed

Youssef, A Samy; Sampath, Raghuram; Freeman, Jacob L; Mattingly, Jameson K; Ramakrishnan, Vijay R

2016-10-01

Loss of olfaction has been considered inevitable in endoscopic endonasal resection of olfactory groove meningiomas. Olfaction preservation may be feasible through an endonasal unilateral transcribriform approach, with the option for expansion using septal transposition and contralateral preservation of the olfactory apparatus. An expanded unilateral endonasal transcribriform approach with septal transposition was performed in five cadaver heads. The approach was applied in a surgical case of a 24 × 26-mm olfactory groove meningioma originating from the right cribriform plate with partially intact olfaction. The surgical approach offered adequate exposure to the anterior skull base bilaterally. The nasal/septal mucosa was preserved on the contralateral side. Gross total resection of the meningioma was achieved with the successful preservation of the contralateral olfactory apparatus and preoperative olfaction. Six months later, the left nasal cavity showed no disruption of the mucosal lining and the right side was at the appropriate stage of healing for a harvested nasoseptal flap. One year later, the preoperative olfactory function was intact and favorably viewed by the patient. Objective testing of olfaction showed microsomia. Olfaction preservation may be feasible in the endoscopic endonasal resection of a unilateral olfactory groove meningioma through a unilateral transcribriform approach with septal transposition and preservation of the contralateral olfactory apparatus.

Modulation of Host Learning in Aedes aegypti Mosquitoes.

PubMed

Vinauger, Clément; Lahondère, Chloé; Wolff, Gabriella H; Locke, Lauren T; Liaw, Jessica E; Parrish, Jay Z; Akbari, Omar S; Dickinson, Michael H; Riffell, Jeffrey A

2018-02-05

How mosquitoes determine which individuals to bite has important epidemiological consequences. This choice is not random; most mosquitoes specialize in one or a few vertebrate host species, and some individuals in a host population are preferred over others. Mosquitoes will also blood feed from other hosts when their preferred is no longer abundant, but the mechanisms mediating these shifts between hosts, and preferences for certain individuals within a host species, remain unclear. Here, we show that olfactory learning may contribute to Aedes aegypti mosquito biting preferences and host shifts. Training and testing to scents of humans and other host species showed that mosquitoes can aversively learn the scent of specific humans and single odorants and learn to avoid the scent of rats (but not chickens). Using pharmacological interventions, RNAi, and CRISPR gene editing, we found that modification of the dopamine-1 receptor suppressed their learning abilities. We further show through combined electrophysiological and behavioral recordings from tethered flying mosquitoes that these odors evoke changes in both behavior and antennal lobe (AL) neuronal responses and that dopamine strongly modulates odor-evoked responses in AL neurons. Not only do these results provide direct experimental evidence that olfactory learning in mosquitoes can play an epidemiological role, but collectively, they also provide neuroanatomical and functional demonstration of the role of dopamine in mediating this learning-induced plasticity, for the first time in a disease vector insect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Identification of Odorant-Receptor Interactions by Global Mapping of the Human Odorome

PubMed Central

Audouze, Karine; Tromelin, Anne; Le Bon, Anne Marie; Belloir, Christine; Petersen, Rasmus Koefoed; Kristiansen, Karsten; Brunak, Søren; Taboureau, Olivier

2014-01-01

The human olfactory system recognizes a broad spectrum of odorants using approximately 400 different olfactory receptors (hORs). Although significant improvements of heterologous expression systems used to study interactions between ORs and odorant molecules have been made, screening the olfactory repertoire of hORs remains a tremendous challenge. We therefore developed a chemical systems level approach based on protein-protein association network to investigate novel hOR-odorant relationships. Using this new approach, we proposed and validated new bioactivities for odorant molecules and OR2W1, OR51E1 and OR5P3. As it remains largely unknown how human perception of odorants influence or prevent diseases, we also developed an odorant-protein matrix to explore global relationships between chemicals, biological targets and disease susceptibilities. We successfully experimentally demonstrated interactions between odorants and the cannabinoid receptor 1 (CB1) and the peroxisome proliferator-activated receptor gamma (PPARγ). Overall, these results illustrate the potential of integrative systems chemical biology to explore the impact of odorant molecules on human health, i.e. human odorome. PMID:24695519

Olfaction Is Related to Motor Function in Older Adults.

PubMed

Tian, Qu; Resnick, Susan M; Studenski, Stephanie A

2017-08-01

Among older adults, both olfaction and motor function predict future cognitive decline and dementia, suggesting potential shared causal pathways. However, it is not known whether olfactory and motor function are independently related in late life. We assessed cross-sectional associations of olfaction with motor and cognitive function, using concurrent data on olfactory function, mobility, balance, fine motor function, manual dexterity, and cognition in 163 Baltimore Longitudinal Study of Aging participants aged 60 and older without common neurological diseases (n = 114 with available cognitive data). Using multiple linear regression, we adjusted for age, sex, race, smoking history, height, and weight for mobility and balance, and education for cognition. We used multiple linear regression to test whether olfaction-motor associations were independent of cognition and depressive symptoms. Olfactory scores were significantly associated with mobility (usual gait speed, rapid gait speed, 400-m walk time, and Health ABC Physical Performance Battery score), balance, fine motor function, and manual dexterity (all p < .05). In those with available cognitive data, additional adjustment for depressive symptoms, verbal memory, or visuoperceptual speed demonstrated especially strong independent relationships with challenging motor tasks such as 400-m walk and nondominant hand manual dexterity (p < .005). This study demonstrates for the first time that, in older adults, olfactory function is associated with mobility, balance, fine motor function, and manual dexterity, and independent of cognitive function, with challenging upper and lower extremity motor function tasks. Longitudinal studies are needed to determine if olfactory performance predicts future mobility and functional decline. Published by Oxford University Press on behalf of The Gerontological Society of America 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Olfactory deposition of inhaled nanoparticles in humans

PubMed Central

Garcia, Guilherme J. M.; Schroeter, Jeffry D.; Kimbell, Julia S.

2016-01-01

Context Inhaled nanoparticles can migrate to the brain via the olfactory bulb, as demonstrated in experiments in several animal species. This route of exposure may be the mechanism behind the correlation between air pollution and human neurodegenerative diseases, including Alzheimer’s disease and Parkinson’s disease. Objectives This manuscript aims to (1) estimate the dose of inhaled nanoparticles that deposit in the human olfactory epithelium during nasal breathing at rest and (2) compare the olfactory dose in humans with our earlier dose estimates for rats. Materials and methods An anatomically-accurate model of the human nasal cavity was developed based on computed tomography scans. The deposition of 1–100 nm particles in the whole nasal cavity and its olfactory region were estimated via computational fluid dynamics (CFD) simulations. Our CFD methods were validated by comparing our numerical predictions for whole-nose deposition with experimental data and previous CFD studies in the literature. Results In humans, olfactory dose of inhaled nanoparticles is highest for 1–2 nm particles with approximately 1% of inhaled particles depositing in the olfactory region. As particle size grows to 100 nm, olfactory deposition decreases to 0.01% of inhaled particles. Discussion and conclusion Our results suggest that the percentage of inhaled particles that deposit in the olfactory region is lower in humans than in rats. However, olfactory dose per unit surface area is estimated to be higher in humans due to their larger minute volume. These dose estimates are important for risk assessment and dose-response studies investigating the neurotoxicity of inhaled nanoparticles. PMID:26194036

Olfactory Mechanisms for Discovery of Odorants to Reduce Insect-Host Contact

PubMed Central

Clark, Jonathan T.; Ray, Anandasankar

2016-01-01

Insects have developed highly sophisticated and sensitive olfactory systems to find animal or plant hosts for feeding. Some insects vector pathogens that cause diseases in hundreds of millions of people and destroy billions of dollars of food products every year. There is great interest, therefore, in understanding how the insect olfactory system can be manipulated to reduce their contact with hosts. Here, we review recent advances in our understanding of insect olfactory detection mechanisms, which may serve as a foundation for designing insect control programs based on manipulation of their behaviors by using odorants. Because every insect species has a unique set of olfactory receptors and olfactory-mediated behaviors, we focus primarily on general principles of odor detection that potentially apply to most insects. While these mechanisms have emerged from studies on model systems for study of insect olfaction, such as Drosophila melanogaster, they provide a foundation for discovery of odorants to repel insects or reduce host-seeking behavior. PMID:27628342

Olfactory preservation during anterior interhemispheric approach for anterior skull base lesions: technical note.

PubMed

Matano, Fumihiro; Murai, Yasuo; Mizunari, Takayuki; Tateyama, Kojiro; Kobayashi, Shiro; Adachi, Koji; Kamiyama, Hiroyasu; Morita, Akio; Teramoto, Akira

2016-01-01

Anosmia is not a rare complication of surgeries that employ the anterior interhemispheric approach. Here, we present a fibrin-gelatin fixation method that provides reinforcement and moisture to help preserve the olfactory nerve when using the anterior interhemispheric approach and describe the results and outcomes of this technique. We analyze the outcomes with this technique in 45 patients who undergo surgery for aneurysms, brain tumors, or other pathologies via the anterior interhemispheric approach. Anosmia occurred in 4 patients (8.8%); it was transient in 2 (4.4%) and permanent in the remaining 2 (4.4%). Brain tumors clearly attached to the olfactory nerve were resected in the patients with permanent anosmia. We found a significant difference in the presence of anosmia between patients with or without lesions that were attaching the olfactory nerve (p = 0.011). Our results suggested that fibrin-gelatin fixation method can reduce the reported risk of anosmia. However, the possibility of olfactory nerve damage is relatively high when operating on brain tumors attaching olfactory nerve.

Implementation of olfactory bulb glomerular-layer computations in a digital neurosynaptic core.

PubMed

Imam, Nabil; Cleland, Thomas A; Manohar, Rajit; Merolla, Paul A; Arthur, John V; Akopyan, Filipp; Modha, Dharmendra S

2012-01-01

We present a biomimetic system that captures essential functional properties of the glomerular layer of the mammalian olfactory bulb, specifically including its capacity to decorrelate similar odor representations without foreknowledge of the statistical distributions of analyte features. Our system is based on a digital neuromorphic chip consisting of 256 leaky-integrate-and-fire neurons, 1024 × 256 crossbar synapses, and address-event representation communication circuits. The neural circuits configured in the chip reflect established connections among mitral cells, periglomerular cells, external tufted cells, and superficial short-axon cells within the olfactory bulb, and accept input from convergent sets of sensors configured as olfactory sensory neurons. This configuration generates functional transformations comparable to those observed in the glomerular layer of the mammalian olfactory bulb. Our circuits, consuming only 45 pJ of active power per spike with a power supply of 0.85 V, can be used as the first stage of processing in low-power artificial chemical sensing devices inspired by natural olfactory systems.

Non-redundant coding of aversive odours in the main olfactory pathway

PubMed Central

Dewan, Adam; Pacifico, Rodrigo; Zhan, Ross; Rinberg, Dmitry; Bozza, Thomas

2013-01-01

Many species are critically dependent on olfaction for survival. In the main olfactory system of mammals, odours are detected by sensory neurons which express a large repertoire of canonical odorant receptors (ORs) and a much smaller repertoire of Trace Amine-Associated Receptors (TAARs)1–4. Odours are encoded in a combinatorial fashion across glomeruli in the main olfactory bulb, with each glomerulus corresponding to a different receptor5–7. The degree to which individual receptor genes contribute to odour perception is unclear. Here we show that genetic deletion of the olfactory TAAR gene family, or even a single TAAR gene, eliminates aversion that mice display to low concentrations of volatile amines and to the odour of predator urine. Our findings identify a role for the TAARs in olfaction, namely in the high-sensitivity detection of innately aversive odours. In addition, our data reveal that aversive amines are represented in a non-redundant fashion, and that individual main olfactory receptor genes can contribute significantly to odour perception. PMID:23624375

Olfactory function in chemical workers exposed to acrylate and methacrylate vapors.

PubMed Central

Schwartz, B S; Doty, R L; Monroe, C; Frye, R; Barker, S

1989-01-01

An investigation of the olfactory function of 731 workers at a chemical facility which manufacturers acrylates and methacrylates was undertaken using a standardized quantitative test. In a cross-sectional analysis of the data, no associations of chemical exposure with olfactory test scores were observed. A nested case-control study designed to evaluate the cumulative effects of exposure on olfactory function, however, revealed elevated crude exposure odds ratios (95% confidence interval) of 2.0 (1.1, 3.8) for all workers and 6.0 (1.7, 21.5) for workers who never smoked cigarettes. Logistic regression analysis, adjusting for multiple confounders, revealed exposure odds ratios of 2.8 (1.1, 7.0) and 13.5 (2.1, 87.6) in these same groups, respectively, and a dose-response relationship between olfactory dysfunction and cumulative exposure scores--semi-quantitative indices of lifetime exposure to the acrylates. The data also revealed decreasing exposure odds ratios with increasing duration since last exposure to these chemicals, suggesting that the effects may be reversible. PMID:2784947

Non-redundant coding of aversive odours in the main olfactory pathway.

PubMed

Dewan, Adam; Pacifico, Rodrigo; Zhan, Ross; Rinberg, Dmitry; Bozza, Thomas

2013-05-23

Many species are critically dependent on olfaction for survival. In the main olfactory system of mammals, odours are detected by sensory neurons that express a large repertoire of canonical odorant receptors and a much smaller repertoire of trace amine-associated receptors (TAARs). Odours are encoded in a combinatorial fashion across glomeruli in the main olfactory bulb, with each glomerulus corresponding to a specific receptor. The degree to which individual receptor genes contribute to odour perception is unclear. Here we show that genetic deletion of the olfactory Taar gene family, or even a single Taar gene (Taar4), eliminates the aversion that mice display to low concentrations of volatile amines and to the odour of predator urine. Our findings identify a role for the TAARs in olfaction, namely, in the high-sensitivity detection of innately aversive odours. In addition, our data reveal that aversive amines are represented in a non-redundant fashion, and that individual main olfactory receptor genes can contribute substantially to odour perception.

Windscapes and olfactory foraging in a large carnivore

PubMed Central

Togunov, Ron R.; Derocher, Andrew E.; Lunn, Nicholas J.

2017-01-01

The theoretical optimal olfactory search strategy is to move cross-wind. Empirical evidence supporting wind-associated directionality among carnivores, however, is sparse. We examined satellite-linked telemetry movement data of adult female polar bears (Ursus maritimus) from Hudson Bay, Canada, in relation to modelled winds, in an effort to understand olfactory search for prey. In our results, the predicted cross-wind movement occurred most frequently at night during winter, the time when most hunting occurs, while downwind movement dominated during fast winds, which impede olfaction. Migration during sea ice freeze-up and break-up was also correlated with wind. A lack of orientation during summer, a period with few food resources, likely reflected reduced cross-wind search. Our findings represent the first quantitative description of anemotaxis, orientation to wind, for cross-wind search in a large carnivore. The methods are widely applicable to olfactory predators and their prey. We suggest windscapes be included as a habitat feature in habitat selection models for olfactory animals when evaluating what is considered available habitat. PMID:28402340

Lateralization of visual learning in the honeybee.

PubMed

Letzkus, Pinar; Boeddeker, Norbert; Wood, Jeff T; Zhang, Shao-Wu; Srinivasan, Mandyam V

2008-02-23

Lateralization is a well-described phenomenon in humans and other vertebrates and there are interesting parallels across a variety of different vertebrate species. However, there are only a few studies of lateralization in invertebrates. In a recent report, we showed lateralization of olfactory learning in the honeybee (Apis mellifera). Here, we investigate lateralization of another sensory modality, vision. By training honeybees on a modified version of a visual proboscis extension reflex task, we find that bees learn a colour stimulus better with their right eye.

Aquatic adaptations in the nose of carnivorans: evidence from the turbinates

PubMed Central

Van Valkenburgh, Blaire; Curtis, Abigail; Samuels, Joshua X; Bird, Deborah; Fulkerson, Brian; Meachen-Samuels, Julie; Slater, Graham J

2011-01-01

Inside the mammalian nose lies a labyrinth of bony plates covered in epithelium collectively known as turbinates. Respiratory turbinates lie anteriorly and aid in heat and water conservation, while more posterior olfactory turbinates function in olfaction. Previous observations on a few carnivorans revealed that aquatic species have relatively large, complex respiratory turbinates and greatly reduced olfactory turbinates compared with terrestrial species. Body heat is lost more quickly in water than air and increased respiratory surface area likely evolved to minimize heat loss. At the same time, olfactory surface area probably diminished due to a decreased reliance on olfaction when foraging under water. To explore how widespread these adaptations are, we documented scaling of respiratory and olfactory turbinate surface area with body size in a variety of terrestrial, freshwater, and marine carnivorans, including pinnipeds, mustelids, ursids, and procyonids. Surface areas were estimated from high-resolution CT scans of dry skulls, a novel approach that enabled a greater sampling of taxa than is practical with fresh heads. Total turbinate, respiratory, and olfactory surface areas correlate well with body size (r2 ≥ 0.7), and are relatively smaller in larger species. Relative to body mass or skull length, aquatic species have significantly less olfactory surface area than terrestrial species. Furthermore, the ratio of olfactory to respiratory surface area is associated with habitat. Using phylogenetic comparative methods, we found strong support for convergence on 1 : 3 proportions in aquatic taxa and near the inverse in terrestrial taxa, indicating that aquatic mustelids and pinnipeds independently acquired similar proportions of olfactory to respiratory turbinates. Constraints on turbinate surface area in the nasal chamber may result in a trade-off between respiratory and olfactory function in aquatic mammals. PMID:21198587

NADPH-diaphorase activity and NO synthase expression in the olfactory epithelium of the bovine.

PubMed

Wenisch, S; Arnhold, S

2010-06-01

NADPH-diaphorase (NADPH-d) staining of the bovine olfactory epithelium was compared with the immunohistochemical localization of nitric oxide synthase (NOS), soluble guanylyl cyclase, and cGMP (cyclic guanosine 3',5'-monophosphate). Out of the three isoforms, only the inducible NOS (NOS-II) was found at the epithelial surface correlating with the strong labelling for NADPH-d. In contrast, light diaphorase staining associated with deeper epithelial regions did not coincide with any NOS immunoreactivity. As there is overlapping expression of NOS-II, soluble guanylyl cyclase and cGMP at the luminal surface morphologically occupied by dendritic knobs of olfactory receptor neurons and microvillar endings of supporting cells, the nitric oxide (NO)/cGMP pathway is likely to be involved in modulating the odour signals during olfactory transduction.

Modulation of cerebral haemodynamic response to olfactory stimuli by emotional valence detected by functional magnetic resonance imaging

PubMed Central

Caous, Cristofer André; Tobo, Patrícia Renovato; Talarico, Vânia Hercília; Gonçales, Luciana Ribeiro Lopes; Yoshimine, Elise; da Cruz Jr, Antonio Cesário; Albuquerque, Cristóvão; Amaro Jr, Edson

2015-01-01

Olfactory perception, although restricted to just a few contexts in everyday life, is key in medicine. Several dementia conditions have been associated with early loss of olfactory discrimination. Despite the fact that several brain areas have been associated with olfaction in functional magnetic resonance imaging (fMRI), the mechanisms by which emotional valence is conveyed to the brain are not fully understood. Methods In this study, we compared cerebral activations by olfactory stimuli using different emotional valence stimuli on event-related fMRI. We used three standard olfactory odorants with different valence (positive, neutral and negative). Forty-three healthy subjects (22 males) were scanned on a 3.0T MR system. Olfactory stimulation was attained through a delivery system synchronized with image acquisition and subjects´ breathing instructions. fMRI data analysis was performed by the FSL package (Oxford University) including head movement correction, GLM modeling of the neurovascular (BOLD) response and group activation maps produced at p<0.05and corrected for multiple comparison. Results Increased cerebral responses within the anterior cingulate, amygdaloid nuclei, as well as the dorsolateral prefrontal, occipital and orbitofrontal cortices were observed in positive and negative valence conditions, while response to neutral valence arousal was less intense and not observed in the amygdaloid complex. The most significant statistical response aroused from the stimuli clusters was observed in the negative condition. Conclusion The results of the present study support the hypothesis that neutral stimuli may be more sensitive to early losses in pathological conditions, particularly dementia. PMID:29213990

Spatial pattern of receptor expression in the olfactory epithelium.

PubMed Central

Nef, P; Hermans-Borgmeyer, I; Artières-Pin, H; Beasley, L; Dionne, V E; Heinemann, S F

1992-01-01

A PCR-based strategy for amplifying putative receptors involved in murine olfaction was employed to isolate a member (OR3) of the seven-transmembrane-domain receptor superfamily. During development, the first cells that express OR3 appear adjacent to the wall of the telencephalic vesicle at embryonic day 10. The OR3 receptor is uniquely expressed in a subset of olfactory cells that have a characteristic bilateral symmetry in the adult olfactory epithelium. This receptor and its specific pattern of expression may serve a functional role in odor coding or, alternatively, may play a role in the development of the olfactory system. Images PMID:1384038

Effect of salinity changes on olfactory memory-related genes and hormones in adult chum salmon Oncorhynchus keta.

PubMed

Kim, Na Na; Choi, Young Jae; Lim, Sang-Gu; Jeong, Minhwan; Jin, Deuk-Hee; Choi, Cheol Young

2015-09-01

Studies of memory formation have recently concentrated on the possible role of N-methyl-d-aspartate receptors (NRs). We examined changes in the expression of three NRs (NR1, NR2B, and NR2C), olfactory receptor (OR), and adrenocorticotropic hormone (ACTH) in chum salmon Oncorhynchus keta using quantitative polymerase chain reaction (QPCR) during salinity change (seawater→50% seawater→freshwater). NRs were significantly detected in the diencephalon and telencephalon and OR was significantly detected in the olfactory epithelium. The expression of NRs, OR, and ACTH increased after the transition to freshwater. We also determined that treatment with MK-801, an antagonist of NRs, decreased NRs in telencephalon cells. In addition, a reduction in salinity was associated with increased levels of dopamine, ACTH, and cortisol (in vivo). Reductions in salinity evidently caused NRs and OR to increase the expression of cortisol and dopamine. We concluded that memory capacity and olfactory imprinting of salmon is related to the salinity of the environment during the migration to spawning sites. Furthermore, salinity affects the memory/imprinting and olfactory abilities, and cortisol and dopamine is also related with olfactory-related memories during migration. Copyright © 2015 Elsevier Inc. All rights reserved.

Detection of Volatile Indicators of Illicit Substances by the Olfactory Receptors of Drosophila melanogaster

PubMed Central

Marshall, Brenton; Warr, Coral G.

2010-01-01

Insects can detect a large range of odors with a numerically simple olfactory system that delivers high sensitivity and accurate discrimination. Therefore, insect olfactory receptors hold great promise as biosensors for detection of volatile organic chemicals in a range of applications. The array of olfactory receptor neurons of Drosophila melanogaster is rapidly becoming the best-characterized natural nose. We have investigated the suitability of Drosophila receptors as detectors for volatiles with applications in law enforcement, emergency response, and security. We first characterized responses of the majority of olfactory neuron types to a set of diagnostic odorants. Being thus able to correctly identify neurons, we then screened for responses from 38 different types of neurons to 35 agents. We identified 13 neuron types with responses to 13 agents. As individual Drosophila receptor genes have been mapped to neuron types, we can infer which genes confer responsiveness to the neurons. The responses were confirmed for one receptor by expressing it in a nonresponsive neuron. The fly olfactory system is mainly adapted to detect volatiles from fermenting fruits. However, our findings establish that volatiles associated with illicit substances, many of which are of nonnatural origin, are also detected by Drosophila receptors. PMID:20530374

Sparse Coding and Lateral Inhibition Arising from Balanced and Unbalanced Dendrodendritic Excitation and Inhibition

PubMed Central

Migliore, Michele; Hines, Michael L.; Shepherd, Gordon M.

2014-01-01

The precise mechanism by which synaptic excitation and inhibition interact with each other in odor coding through the unique dendrodendritic synaptic microcircuits present in olfactory bulb is unknown. Here a scaled-up model of the mitral–granule cell network in the rodent olfactory bulb is used to analyze dendrodendritic processing of experimentally determined odor patterns. We found that the interaction between excitation and inhibition is responsible for two fundamental computational mechanisms: (1) a balanced excitation/inhibition in strongly activated mitral cells, leading to a sparse representation of odorant input, and (2) an unbalanced excitation/inhibition (inhibition dominated) in surrounding weakly activated mitral cells, leading to lateral inhibition. These results suggest how both mechanisms can carry information about the input patterns, with optimal level of synaptic excitation and inhibition producing the highest level of sparseness and decorrelation in the network response. The results suggest how the learning process, through the emergent development of these mechanisms, can enhance odor representation of olfactory bulb. PMID:25297097

The wiring diagram of a glomerular olfactory system

PubMed Central

Berck, Matthew E; Khandelwal, Avinash; Claus, Lindsey; Hernandez-Nunez, Luis; Si, Guangwei; Tabone, Christopher J; Li, Feng; Truman, James W; Fetter, Rick D; Louis, Matthieu; Samuel, Aravinthan DT; Cardona, Albert

2016-01-01

The sense of smell enables animals to react to long-distance cues according to learned and innate valences. Here, we have mapped with electron microscopy the complete wiring diagram of the Drosophila larval antennal lobe, an olfactory neuropil similar to the vertebrate olfactory bulb. We found a canonical circuit with uniglomerular projection neurons (uPNs) relaying gain-controlled ORN activity to the mushroom body and the lateral horn. A second, parallel circuit with multiglomerular projection neurons (mPNs) and hierarchically connected local neurons (LNs) selectively integrates multiple ORN signals already at the first synapse. LN-LN synaptic connections putatively implement a bistable gain control mechanism that either computes odor saliency through panglomerular inhibition, or allows some glomeruli to respond to faint aversive odors in the presence of strong appetitive odors. This complete wiring diagram will support experimental and theoretical studies towards bridging the gap between circuits and behavior. DOI: http://dx.doi.org/10.7554/eLife.14859.001 PMID:27177418

Local corticotropin releasing hormone (CRH) signals to its receptor CRHR1 during postnatal development of the mouse olfactory bulb.

PubMed

Garcia, Isabella; Bhullar, Paramjit K; Tepe, Burak; Ortiz-Guzman, Joshua; Huang, Longwen; Herman, Alexander M; Chaboub, Lesley; Deneen, Benjamin; Justice, Nicholas J; Arenkiel, Benjamin R

2016-01-01

Neuropeptides play important physiological functions during distinct behaviors such as arousal, learning, memory, and reproduction. However, the role of local, extrahypothalamic neuropeptide signaling in shaping synapse formation and neuronal plasticity in the brain is not well understood. Here, we characterize the spatiotemporal expression profile of the neuropeptide corticotropin-releasing hormone (CRH) and its receptor CRHR1 in the mouse OB throughout development. We found that CRH-expressing interneurons are present in the external plexiform layer, that its cognate receptor is expressed by granule cells, and show that both CRH and CRHR1 expression enriches in the postnatal period when olfaction becomes important towards olfactory-related behaviors. Further, we provide electrophysiological evidence that CRHR1-expressing granule cells functionally respond to CRH ligand, and that the physiological circuitry of CRHR1 knockout mice is abnormal, leading to impaired olfactory behaviors. Together, these data suggest a physiologically relevant role for local CRH signaling towards shaping the neuronal circuitry within the mouse OB.

Odor Discrimination in Drosophila: From Neural Population Codes to Behavior

PubMed Central

Parnas, Moshe; Lin, Andrew C.; Huetteroth, Wolf; Miesenböck, Gero

2013-01-01

Summary Taking advantage of the well-characterized olfactory system of Drosophila, we derive a simple quantitative relationship between patterns of odorant receptor activation, the resulting internal representations of odors, and odor discrimination. Second-order excitatory and inhibitory projection neurons (ePNs and iPNs) convey olfactory information to the lateral horn, a brain region implicated in innate odor-driven behaviors. We show that the distance between ePN activity patterns is the main determinant of a fly’s spontaneous discrimination behavior. Manipulations that silence subsets of ePNs have graded behavioral consequences, and effect sizes are predicted by changes in ePN distances. ePN distances predict only innate, not learned, behavior because the latter engages the mushroom body, which enables differentiated responses to even very similar odors. Inhibition from iPNs, which scales with olfactory stimulus strength, enhances innate discrimination of closely related odors, by imposing a high-pass filter on transmitter release from ePN terminals that increases the distance between odor representations. PMID:24012006

Social Recognition Memory Requires Two Stages of Protein Synthesis in Mice

ERIC Educational Resources Information Center

Wolf, Gerald; Engelmann, Mario; Richter, Karin

2005-01-01

Olfactory recognition memory was tested in adult male mice using a social discrimination task. The testing was conducted to begin to characterize the role of protein synthesis and the specific brain regions associated with activity in this task. Long-term olfactory recognition memory was blocked when the protein synthesis inhibitor anisomycin was…

Evolution of olfaction in non-avian theropod dinosaurs and birds

PubMed Central

Zelenitsky, Darla K.; Therrien, François; Ridgely, Ryan C.; McGee, Amanda R.; Witmer, Lawrence M.

2011-01-01

Little is known about the olfactory capabilities of extinct basal (non-neornithine) birds or the evolutionary changes in olfaction that occurred from non-avian theropods through modern birds. Although modern birds are known to have diverse olfactory capabilities, olfaction is generally considered to have declined during avian evolution as visual and vestibular sensory enhancements occurred in association with flight. To test the hypothesis that olfaction diminished through avian evolution, we assessed relative olfactory bulb size, here used as a neuroanatomical proxy for olfactory capabilities, in 157 species of non-avian theropods, fossil birds and living birds. We show that relative olfactory bulb size increased during non-avian maniraptoriform evolution, remained stable across the non-avian theropod/bird transition, and increased during basal bird and early neornithine evolution. From early neornithines through a major part of neornithine evolution, the relative size of the olfactory bulbs remained stable before decreasing in derived neoavian clades. Our results show that, rather than decreasing, the importance of olfaction actually increased during early bird evolution, representing a previously unrecognized sensory enhancement. The relatively larger olfactory bulbs of earliest neornithines, compared with those of basal birds, may have endowed neornithines with improved olfaction for more effective foraging or navigation skills, which in turn may have been a factor allowing them to survive the end-Cretaceous mass extinction. PMID:21490022

Ultrastructural localization of connexins (Cx36, Cx43, Cx45), glutamate receptors and aquaporin-4 in rodent olfactory mucosa, olfactory nerve and olfactory bulb

PubMed Central

RASH, JOHN E.; DAVIDSON, KIMBERLY G. V.; KAMASAWA, NAOMI; YASUMURA, THOMAS; KAMASAWA, MASAMI; ZHANG, CHUNBO; MICHAELS, ROBIN; RESTREPO, DIEGO; OTTERSEN, OLE P.; OLSON, CARL O.; NAGY, JAMES I.

2006-01-01

Odorant/receptor binding and initial olfactory information processing occurs in olfactory receptor neurons (ORNs) within the olfactory epithelium. Subsequent information coding involves high-frequency spike synchronization of paired mitral/tufted cell dendrites within olfactory bulb (OB) glomeruli via positive feedback between glutamate receptors and closely-associated gap junctions. With mRNA for connexins Cx36, Cx43 and Cx45 detected within ORN somata and Cx36 and Cx43 proteins reported in ORN somata and axons, abundant gap junctions were proposed to couple ORNs. We used freeze-fracture replica immunogold labeling (FRIL) and confocal immunofluorescence microscopy to examine Cx36, Cx43 and Cx45 protein in gap junctions in olfactory mucosa, olfactory nerve and OB in adult rats and mice and early postnatal rats. In olfactory mucosa, Cx43 was detected in gap junctions between virtually all intrinsic cell types except ORNs and basal cells; whereas Cx45 was restricted to gap junctions in sustentacular cells. ORN axons contained neither gap junctions nor any of the three connexins. In OB, Cx43 was detected in homologous gap junctions between almost all cell types except neurons and oligodendrocytes. Cx36 and, less abundantly, Cx45 were present in neuronal gap junctions, primarily at “mixed” glutamatergic/electrical synapses between presumptive mitral/tufted cell dendrites. Genomic analysis revealed multiple miRNA (micro interfering RNA) binding sequences in 3′-untranslated regions of Cx36, Cx43 and Cx45 genes, consistent with cell-type-specific post-transcriptional regulation of connexin synthesis. Our data confirm absence of gap junctions between ORNs, and support Cx36- and Cx45-containing gap junctions at glutamatergic mixed synapses between mitral/tufted cells as contributing to higher-order information coding within OB glomeruli. PMID:16841170

Effect of a thymol application on olfactory memory and gene expression levels in the brain of the honeybee Apis mellifera.

PubMed

Bonnafé, Elsa; Drouard, Florian; Hotier, Lucie; Carayon, Jean-Luc; Marty, Pierre; Treilhou, Michel; Armengaud, Catherine

2015-06-01

Essential oils are used by beekeepers to control the Varroa mites that infest honeybee colonies. So, bees can be exposed to thymol formulations in the hive. The effects of the monoterpenoid thymol were explored on olfactory memory and gene expression in the brain of the honeybee. In bees previously exposed to thymol (10 or 100 ng/bee), the specificity of the response to the conditioned stimulus (CS) was lost 24 h after learning. Besides, the octopamine receptor OA1 gene Amoa1 showed a significant decrease of expression 3 h after exposure with 10 or 100 ng/bee of thymol. With the same doses, expression of Rdl gene, coding for a GABA receptor subunit, was not significantly modified but the trpl gene was upregulated 1 and 24 h after exposure to thymol. These data indicated that the genes coding for the cellular targets of thymol could be rapidly regulated after exposure to this molecule. Memory and sensory processes should be investigated in bees after chronic exposure in the hive to thymol-based preparations.

DELINEATING TOXIC AREAS BY CANINE OLFACTION

EPA Science Inventory

A research project was undertaken to learn how the highly acute olfactory sensitivity of the canine could be applied with advantage to environmental problems. The objectives were to determine how dogs could be trained to detect hazardous and toxic pollutants in the environment an...

Internal tobacco industry research on olfactory and trigeminal nerve response to nicotine and other smoke components.

PubMed

Megerdichian, Christine L; Rees, Vaughan W; Wayne, Geoffrey Ferris; Connolly, Gregory N

2007-11-01

Evidence has shown that factors other than the central pharmacological effects of nicotine are important in promoting smoking behavior. One such non-nicotine effect includes sensory stimulation, which may promote smoking by developing learned associations with nicotine's rewarding effects, or by constituting a rewarding experience independent of nicotine. The present study used internal tobacco industry documents to examine industry efforts to understand and manipulate stimulation of the sensory nerves by tobacco smoke, and the influence of sensory stimulation on smoker behavior. Research focused on sensory nerves of the head and neck, including the olfactory nerve, which carries flavor and odor, and the trigeminal nerve, which carries irritant information. The tobacco industry maintained a systematic research program designed to elucidate an understanding of responses of sensory nerves to nicotine and other components of tobacco smoke, and attempted to develop nicotine-like compounds that would enhance sensory responses in smokers. Industry research appeared intended to aid in the development of new products with greater consumer appeal. The potential influence of sensory response in enhancing nicotine dependence through an associative mechanism was acknowledged by the tobacco industry, but evidence for research in this area was limited. These findings add to evidence of industry manipulation of sensory factors to enhance smoking behavior and may have implications for development of more effective treatment strategies, including more "acceptable" nicotine replacement therapies.

Routine magnetic resonance imaging for idiopathic olfactory loss: a modeling-based economic evaluation.

PubMed

Rudmik, Luke; Smith, Kristine A; Soler, Zachary M; Schlosser, Rodney J; Smith, Timothy L

2014-10-01

Idiopathic olfactory loss is a common clinical scenario encountered by otolaryngologists. While trying to allocate limited health care resources appropriately, the decision to obtain a magnetic resonance imaging (MRI) scan to investigate for a rare intracranial abnormality can be difficult. To evaluate the cost-effectiveness of ordering routine MRI in patients with idiopathic olfactory loss. We performed a modeling-based economic evaluation with a time horizon of less than 1 year. Patients included in the analysis had idiopathic olfactory loss defined by no preceding viral illness or head trauma and negative findings of a physical examination and nasal endoscopy. Routine MRI vs no-imaging strategies. We developed a decision tree economic model from the societal perspective. Effectiveness, probability, and cost data were obtained from the published literature. Litigation rates and costs related to a missed diagnosis were obtained from the Physicians Insurers Association of America. A univariate threshold analysis and multivariate probabilistic sensitivity analysis were performed to quantify the degree of certainty in the economic conclusion of the reference case. The comparative groups included those who underwent routine MRI of the brain with contrast alone and those who underwent no brain imaging. The primary outcome was the cost per correct diagnosis of idiopathic olfactory loss. The mean (SD) cost for the MRI strategy totaled $2400.00 ($1717.54) and was effective 100% of the time, whereas the mean (SD) cost for the no-imaging strategy totaled $86.61 ($107.40) and was effective 98% of the time. The incremental cost-effectiveness ratio for the MRI strategy compared with the no-imaging strategy was $115 669.50, which is higher than most acceptable willingness-to-pay thresholds. The threshold analysis demonstrated that when the probability of having a treatable intracranial disease process reached 7.9%, the incremental cost-effectiveness ratio for MRI vs no imaging was $24 654.38. The probabilistic sensitivity analysis demonstrated that the no-imaging strategy was the cost-effective decision with 81% certainty at a willingness-to-pay threshold of $50 000. This economic evaluation suggests that the most cost-effective decision is to not obtain a routine MRI scan of the brain in patients with idiopathic olfactory loss. Outcomes from this study may be used to counsel patients and aid in the decision-making process.

Fetal alcohol exposure leads to abnormal olfactory bulb development and impaired odor discrimination in adult mice

PubMed Central

2011-01-01

Background Children whose mothers consumed alcohol during pregnancy exhibit widespread brain abnormalities and a complex array of behavioral disturbances. Here, we used a mouse model of fetal alcohol exposure to investigate relationships between brain abnormalities and specific behavioral alterations during adulthood. Results Mice drank a 10% ethanol solution throughout pregnancy. When fetal alcohol-exposed offspring reached adulthood, we used high resolution MRI to conduct a brain-wide screen for structural changes and found that the largest reduction in volume occurred in the olfactory bulbs. Next, we tested adult mice in an associative olfactory task and found that fetal alcohol exposure impaired discrimination between similar odors but left odor memory intact. Finally, we investigated olfactory bulb neurogenesis as a potential mechanism by performing an in vitro neurosphere assay, in vivo labeling of new cells using BrdU, and in vivo labeling of new cells using a transgenic reporter system. We found that fetal alcohol exposure decreased the number of neural precursor cells in the subependymal zone and the number of new cells in the olfactory bulbs during the first few postnatal weeks. Conclusions Using a combination of techniques, including structural brain imaging, in vitro and in vivo cell detection methods, and behavioral testing, we found that fetal alcohol exposure results in smaller olfactory bulbs and impairments in odor discrimination that persist into adulthood. Furthermore, we found that these abnormalities in olfactory bulb structure and function may arise from deficits in the generation of new olfactory bulb neurons during early postnatal development. PMID:21736737

Expression of Olfactory Signaling Genes in the Eye

PubMed Central

Velmeshev, Dmitry; Faghihi, Mohammad; Shestopalov, Valery I.; Slepak, Vladlen Z.

2014-01-01

Purpose To advance our understanding how the outer eye interacts with its environment, we asked which cellular receptors are expressed in the cornea, focusing on G protein-coupled receptors. Methods Total RNA from the mouse cornea was subjected to next-generation sequencing using the Illumina platform. The data was analyzed with TopHat and CuffLinks software packages. Expression of a representative group of genes detected by RNA-seq was further analyzed by RT-PCR and in situ hybridization using RNAscope technology and fluorescent microscopy. Results We generated more than 46 million pair-end reads from mouse corneal RNA. Bioinformatics analysis revealed that the mouse corneal transcriptome reconstructed from these reads represents over 10,000 gene transcripts. We identified 194 GPCR transcripts, of which 96 were putative olfactory receptors. RT-PCR analysis confirmed the presence of several olfactory receptors and related genes, including olfactory marker protein and the G protein associated with olfaction, Gαolf. In situ hybridization showed that mRNA for olfactory marker protein, Gαolf and possibly some olfactory receptors were found in the corneal epithelial cells. In addition to the corneal epithelium, Gαolf was present in the ganglionic and inner nuclear layers of the retina. One of the olfactory receptors, Olfr558, was present primarily in vessels of the eye co-stained with antibodies against alpha-smooth muscle actin, indicating expression in arterioles. Conclusions Several species of mRNA encoding putative olfactory receptors and related genes are expressed in the mouse cornea and other parts of the eye indicating they may play a role in sensing chemicals in the ocular environment. PMID:24789354

Effect of ginkgo biloba and dexamethasone in the treatment of 3-methylindole-induced anosmia mouse model.

PubMed

Lee, Chul Hee; Mo, Ji-Hun; Shim, Seung Hee; Ahn, Jung-Min; Kim, Jeong-Whun

2008-01-01

Olfactory loss is a challenging disease. Although glucocorticoid is sometimes used for the treatment of anosmia, it has been reported that it potentiated neural damage in the early phase of treatment. This study is designed to identify the effect of ginkgo biloba, an antioxidant that acts as a free radical scavenger, in the treatment of olfactory injury aggravated by dexamethasone. Anosmia mouse model was induced by i.p. injection of 3-methylindole (3-MI). Twenty-five mice were divided into one control group without anosmia and four anosmia treatment groups (given treatments of dexamethasone and/or ginkgo biloba). The effects of treatment were evaluated by behavioral test, Western blot, and immunohistochemistry 2 weeks after 3-MI injection. Induction of anosmia was confirmed by behavioral tests. The thickness and cell number of olfactory neuroepithelium were decreased more significantly in the dexamethasone treatment group than in the combination treatment group. The expression of olfactory marker protein (OMP) in olfactory epithelium was more decreased also in the dexamethasone treatment group than in the combination treatment group. The expression of OMP was decreased significantly in the olfactory bulbs of anosmia groups but there were no differences between the anosmia treatment groups. Dexamethasone treatment was associated with further deterioration of olfactory injury by 3-MI and it was recovered by combination treatment of dexamethasone and ginkgo biloba. The antioxidant effect of ginkgo biloba might play a role in restoration of olfactory loss and it was effective only when oxidative stress is maximized by dexamethasone.

From antenna to antenna: lateral shift of olfactory memory recall by honeybees.

PubMed

Rogers, Lesley J; Vallortigara, Giorgio

2008-06-04

Honeybees, Apis mellifera, readily learn to associate odours with sugar rewards and we show here that recall of the olfactory memory, as demonstrated by the bee extending its proboscis when presented with the trained odour, involves first the right and then the left antenna. At 1-2 hour after training using both antennae, recall is possible mainly when the bee uses its right antenna but by 6 hours after training a lateral shift has occurred and the memory can now be recalled mainly when the left antenna is in use. Long-term memory one day after training is also accessed mainly via the left antenna. This time-dependent shift from right to left antenna is also seen as side biases in responding to odour presented to the bee's left or right side. Hence, not only are the cellular events of memory formation similar in bees and vertebrate species but also the lateralized networks involved may be similar. These findings therefore seem to call for remarkable parallel evolution and suggest that the proper functioning of memory formation in a bilateral animal, either vertebrate or invertebrate, requires lateralization of processing.

Age- and sex-related disturbance in a battery of sensorimotor and cognitive tasks in Kunming mice.

PubMed

Chen, Gui-Hai; Wang, Yue-Ju; Zhang, Li-Qun; Zhou, Jiang-Ning

2004-12-15

A battery of tasks, i.e. beam walking, open field, tightrope, radial six-arm water maze (RAWM), novel-object recognition and olfactory discrimination, was used to determine whether there was age- and sex-related memory deterioration in Kunming (KM) mice, and whether these tasks are independent or correlated with each other. Two age groups of KM mice were used: a younger group (7-8 months old, 12 males and 11 females) and an older group (17-18 months old, 12 males and 12 females). The results showed that the spatial learning ability and memory in the RAWM were lower in older female KM mice relative to younger female mice and older male mice. Consistent with this, in the novel-object recognition task, a non-spatial cognitive task, older female mice but not older male mice had impairment of short-term memory. In olfactory discrimination, another non-spatial task, the older mice retained this ability. Interestingly, female mice performed better than males, especially in the younger group. The older females exhibited sensorimotor impairment in the tightrope task and low locomotor activity in the open-field task. Moreover, older mice spent a longer time in the peripheral squares of the open-field than younger ones. The non-spatial cognitive performance in the novel-object recognition and olfactory discrimination tasks was related to performance in the open-field, whereas the spatial cognitive performance in the RAWM was not related to performance in any of the three sensorimotor tasks. These results suggest that disturbance of spatial learning and memory, as well as selective impairment of non-spatial learning and memory, existed in older female KM mice.

Pre-pupation behaviour of the aphid parasitoid Aphidius ervi (Haliday) and its consequences for pre-imaginal learning

NASA Astrophysics Data System (ADS)

Gutiérrez-Ibáñez, Cristián; Villagra, Cristian A.; Niemeyer, Hermann M.

2007-07-01

Olfactory learning may occur at different stages of insect ontogeny. In parasitoid wasps, it has been mostly shown at adult emergence, whilst it remains controversial at pre-imaginal stages. We followed larval growth of the parasitoid wasp, Aphidius ervi Haliday, inside the host aphid, Acyrthosiphom pisum Harris, and characterised in detail the behaviour of third instar larvae. We found that just before cocoon spinning begins, the third instar larva bites a hole through the ventral side of the mummified aphid exoskeleton. We then evaluated whether this period of exposure to the external environment represented a sensitive stage for olfactory learning. In our first experiment, the third instar larvae were allowed to spin their cocoon on the host plant ( Vicia faba L.) surface or on a plastic plate covering the portion of the host plant exposed to the ventral opening. Recently emerged adults of the first group showed a preference for plant volatiles in a glass Y-olfactometer, whereas no preference was found in adults of the second group. In a second experiment, during the period in which the aphid carcass remains open or is being sealed by cocoon spinning, third instar larvae were exposed for 24 h to either vanilla odours or water vapours as control. In this experiment, half of the parasitoid larvae were later excised from the mummy to avoid further exposure to vanilla. Adult parasitoids exposed to vanilla during the larval ventral opening of the mummy showed a significant preference for vanilla odours in the olfactometer, regardless of excision from the mummy. The larval behaviour described and the results of the manipulations performed are discussed as evidences for the acquisition of olfactory memory during the larval stage and its persistence through metamorphosis.

Olfactory bulb and olfactory sulcus depths are associated with disease duration and attack frequency in multiple sclerosis patients.

PubMed

Tanik, Nermin; Serin, Halil Ibrahim; Celikbilek, Asuman; Inan, Levent Ertugrul; Gundogdu, Fatma

2015-11-15

Multiple sclerosis (MS) is a neuroinflammatory and neurodegenerative disease that progresses to axonal loss and demyelinization. Olfactory dysfunction in patients with MS has been reported frequently. We were interested in the associations of olfactory bulb (OB) and olfactory sulcus depth (OSD) with disease duration and attack frequency. We included 25 patients with MS and 30 age- and sex-matched controls in this study. The Expanded Disability Status Scale, Beck Depression Inventory, and Mini Mental State Examination were applied. OB, OSD, and magnetic resonance imaging plaque numbers were calculated. OB volume and OSD in patients with MS were significantly lower than those in the control group (right and left OB: p<0.001; right OSD: p=0.001; and left OSD: p=0.039). Disease duration was negatively correlated with right and left OB volume (right OB: r=-0.434, p=0.030 and left OB: r=-0.518, p=0.008). Attack frequency was negatively correlated with left OB volume and left OSD (left OB: r=-0.428, p=0.033 and left OSD: r=-0.431, p=0.032). The OB and OSD were atrophied significantly in patients with MS, and this was correlated with disease duration and attack frequency. The left side tended to be dominant. Copyright © 2015 Elsevier B.V. All rights reserved.

Lesion of olfactory epithelium attenuates expression of morphine-induced behavioral sensitization and reinstatement of drug-primed conditioned place preference in mice.

PubMed

Niu, Haichen; Zheng, Yingwei; Huma, Tanzeel; Rizak, Joshua D; Li, Ling; Wang, Guimei; Ren, He; Xu, Liqi; Yang, Jianzhen; Ma, Yuanye; Lei, Hao

2013-01-01

Previous studies have shown that olfactory impairment by disrupting the olfactory epithelium prior to morphine administration attenuated the development addiction-related behaviors. However, it is unclear whether olfactory impairment will affect the expression of already established addiction-related behaviors. To address this issue, mice were conditioned with morphine to induce behavioral sensitization and condition placed preference (CPP). After an abstinence period, the animals were subjected to either an intranasal ZnSO(4) effusion (ZnE) or sham treatment with saline. Behavioral sensitization and CPP reinstatement were evaluated 24h later, as well as the expression of c-Fos protein, a marker of activated neural sites, in brain regions of interest. It was found that ZnE treatment attenuated morphine-induced behavioral sensitization and reinstatement of CPP. Compared to the saline-treated ones, the ZnE-treated animals showed reduced c-Fos expression in the nucleus accumbens (NAc) associated with behavioral sensitization, and in the NAc, cingulate cortex, dentate gyrus, amygdala, lateral hypothalamus and ventral tegmental area associated with CPP reinstatement. Together, these results demonstrated that acute olfactory impairment could attenuate already established addiction-related behaviors and expression of c-Fos in drug addiction related brain regions, perhaps by affecting the coordination between reward and motivational systems in the brain. Copyright © 2012 Elsevier Inc. All rights reserved.

Non-imaged based method for matching brains in a common anatomical space for cellular imagery.

PubMed

Midroit, Maëllie; Thevenet, Marc; Fournel, Arnaud; Sacquet, Joelle; Bensafi, Moustafa; Breton, Marine; Chalençon, Laura; Cavelius, Matthias; Didier, Anne; Mandairon, Nathalie

2018-04-22

Cellular imagery using histology sections is one of the most common techniques used in Neuroscience. However, this inescapable technique has severe limitations due to the need to delineate regions of interest on each brain, which is time consuming and variable across experimenters. We developed algorithms based on a vectors field elastic registration allowing fast, automatic realignment of experimental brain sections and associated labeling in a brain atlas with high accuracy and in a streamlined way. Thereby, brain areas of interest can be finely identified without outlining them and different experimental groups can be easily analyzed using conventional tools. This method directly readjusts labeling in the brain atlas without any intermediate manipulation of images. We mapped the expression of cFos, in the mouse brain (C57Bl/6J) after olfactory stimulation or a non-stimulated control condition and found an increased density of cFos-positive cells in the primary olfactory cortex but not in non-olfactory areas of the odor-stimulated animals compared to the controls. Existing methods of matching are based on image registration which often requires expensive material (two-photon tomography mapping or imaging with iDISCO) or are less accurate since they are based on mutual information contained in the images. Our new method is non-imaged based and relies only on the positions of detected labeling and the external contours of sections. We thus provide a new method that permits automated matching of histology sections of experimental brains with a brain reference atlas. Copyright © 2018 Elsevier B.V. All rights reserved.

Immunocytochemical characterisation of ensheathing glia in the olfactory and vomeronasal systems of Ambystoma mexicanum (Caudata: Ambystomatidae).

PubMed

Lazzari, Maurizio; Bettini, Simone; Franceschini, Valeria

2016-03-01

The olfactory and vomeronasal systems of vertebrates are characterised by neurogenesis occurring throughout life. The regenerative ability of olfactory receptor neurons relies on specific glial cells, the olfactory and vomeronasal axon-surrounding cells. Numerous studies have examined mammalian olfactory ensheathing cells which are considered potential candidates for spinal cord injury repair using cell-based therapy. With regard to non-mammalian vertebrates, limited information is available on these glial cells in fish, and there is no information on them in terrestrial anamniotes, the amphibians. In the present research, we studied the immunocytochemical characteristics of axon-surrounding cells in Ambystoma mexicanum. Urodeles have relatively simple olfactory and vomeronasal systems, and represent a good model for studying ensheathing cells in extant representatives of basal tetrapods. Sections from the decalcified heads of A. mexicanum were immunocytochemically processed for the detection of proteins used in research on mammalian olfactory-ensheathing cells. S100, GFAP and NCAM were clearly observed. p75NTR, Gal-1 and PSA-NCAM showed weak staining. No vimentin immunopositivity was observed. The corresponding areas of the olfactory and vomeronasal pathways displayed the same staining characteristics, with the exception of Gal-1, p75NTR and PSA-NCAM in the mucosae. The degree of marker expression was not uniform throughout the sensory pathways. In contrast to fish, both olfactory and vomeronasal nerves displayed uniform staining intensity. This study showed that some markers for mammalian and fish-ensheathing glia are also applicable in urodeles. The olfactory systems of vertebrates show similarities, and also clear dissimilarities. Further investigations are required to ascertain the functional significance of these regional and interspecific differences.

A cortical pathway to olfactory naming: evidence from primary progressive aphasia

PubMed Central

Rogalski, Emily; Harrison, Theresa; Mesulam, M.-Marsel; Gottfried, Jay A.

2013-01-01

It is notoriously difficult to name odours. Without the benefit of non-olfactory information, even common household smells elude our ability to name them. The neuroscientific basis for this olfactory language ‘deficit’ is poorly understood, and even basic models to explain how odour inputs gain access to transmodal representations required for naming have not been put forward. This study used patients with primary progressive aphasia, a clinical dementia syndrome characterized by primary deficits in language, to investigate the interactions between olfactory inputs and lexical access by assessing behavioural performance of olfactory knowledge and its relationship to brain atrophy. We specifically hypothesized that the temporal pole would play a key role in linking odour object representations to transmodal networks, given its anatomical proximity to olfactory and visual object processing areas. Behaviourally, patients with primary progressive aphasia with non-semantic subtypes were severely impaired on an odour naming task, in comparison with an age-matched control group. However, with the availability of picture cues or word cues, odour matching performance approached control levels, demonstrating an inability to retrieve but not to recognize the name and nature of the odorant. The magnitude of cortical thinning in the temporal pole was found to correlate with reductions in odour familiarity and odour matching to visual cues, whereas the inferior frontal gyrus correlated with both odour naming and matching. Volumetric changes in the mediodorsal thalamus correlated with the proportion of categorical mismatch errors, indicating a possible role of this region in error-signal monitoring to optimize recognition of associations linked to the odour. A complementary analysis of patients with the semantic subtype of primary progressive aphasia, which is associated with marked temporopolar atrophy, revealed much more pronounced impairments of odour naming and matching. In identifying the critical role of the temporal pole and inferior frontal gyrus in transmodal linking and verbalization of olfactory objects, our findings provide a new neurobiological foundation for understanding why even common odours are hard to name. PMID:23471695

Olfactory cleft computed tomography analysis and olfaction in chronic rhinosinusitis

PubMed Central

Kohli, Preeti; Schlosser, Rodney J.; Storck, Kristina

2016-01-01

Background: Volumetric analysis of the olfactory cleft by using computed tomography has been associated with olfaction in patients with chronic rhinosinusitis (CRS). However, existing studies have not comprehensively measured olfaction, and it thus remains unknown whether correlations differ across specific dimensions of odor perception. Objective: To use comprehensive measures of patient-reported and objective olfaction to evaluate the relationship between volumetric olfactory cleft opacification and olfaction. Methods: Olfaction in patients with CRS was evaluated by using “Sniffin' Sticks” tests and a modified version of the Questionnaire of Olfactory Disorders. Olfactory cleft opacification was quantified by using two- and three-dimensional, computerized volumetric analysis. Correlations between olfactory metrics and olfactory cleft opacification were then calculated. Results: The overall CRS cohort included 26 patients without nasal polyposis (CRSsNP) (68.4%) and 12 patients with nasal polyposis (CRSwNP) (31.6%). Across the entire cohort, total olfactory cleft opacification was 82.8%, with greater opacification in the CRSwNP subgroup compared with CRSsNP (92.3 versus 78.4%, p < 0.001). The percent total volume opacification correlated with the total Sniffin' Sticks score (r = −0.568, p < 0.001) as well as individual threshold, discrimination, and identification scores (p < 0.001 for all). Within the CRSwNP subgroup, threshold (r = −0.616, p = 0.033) and identification (r = −0.647, p = 0.023) remained highly correlated with total volume opacification. In patients with CRSsNP, the threshold correlated with total volume scores (r = −0.457, p = 0.019), with weaker and nonsignificant correlations for discrimination and identification. Correlations between total volume opacification and the Questionnaire of Olfactory Disorders were qualitatively similar to objective olfactory findings in both CRSwNP (r = −0.566, p = 0.070) and CRSsNP (r = −0.310, p = 0.141) subgroups, although neither reached significance. When examined by two-dimensional planes, the percent opacification of the anterior plane had the strongest correlations with objective olfaction. Conclusion: Olfactory cleft opacification correlated with objective measures of olfaction in patients with CRS, which correlated with threshold values in patients with CRSsNP and all dimensions of olfaction in those with CRSwNP. PMID:28124650

Decreased retention of olfactory predator recognition in juvenile surgeon fish exposed to pesticide.

PubMed

Bertucci, Frédéric; Jacob, Hugo; Mignucci, Alexandre; Gache, Camille; Roux, Natacha; Besson, Marc; Berthe, Cécile; Metian, Marc; Lecchini, David

2018-06-04

Dory, the animated surgeonfish created by the Pixar Animation studios, famously suffered from short-term memory loss leading to many adventures. In reality, many fishes have excellent cognitive abilities and are able to learn and retain important information such as the identity of predators. However, if and how cognition can be affected by anthropogenically altered oceanic conditions is poorly understood. Here, we examine the effect of a widely used pesticide, chlorpyrifos, on the retention of acquired predator recognition in post-larval stage of the surgeonfish Acanthurus triostegus. Through associative learning, post-larvae of A. triostegus were first observed to forage significantly less in the presence of conspecific alarm cues and alarm cues associated to a predator's odor. The retention of this anti-predator behavior was estimated to last between 2 and 5 days in the absence of pesticide. However, environmentally-relevant concentrations of chlorpyrifos (1 μg.L -1 ) induced the loss of this acquired predator recognition. This reduced ability to recognize learned predators is discussed as it may lead to more vulnerable fish communities in coastal areas subjected to organophosphate pesticide pollution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Cortical Odor Processing in Health and Disease

PubMed Central

Wilson, Donald A.; Xu, Wenjin; Sadrian, Benjamin; Courtiol, Emmanuelle; Cohen, Yaniv; Barnes, Dylan C.

2014-01-01

The olfactory system has a rich cortical representation, including a large archicortical component present in most vertebrates, and in mammals neocortical components including the entorhinal and orbitofrontal cortices. Together, these cortical components contribute to normal odor perception and memory. They help transform the physicochemical features of volatile molecules inhaled or exhaled through the nose into the perception of odor objects with rich associative and hedonic aspects. This chapter focuses on how olfactory cortical areas contribute to odor perception and begins to explore why odor perception is so sensitive to disease and pathology. Odor perception is disrupted by a wide range of disorders including Alzheimer’s disease, Parkinson’s disease, schizophrenia, depression, autism, and early life exposure to toxins. This olfactory deficit often occurs despite maintained functioning in other sensory systems. Does the unusual network of olfactory cortical structures contribute to this sensitivity? PMID:24767487

Olfactory bulb gamma oscillations are enhanced with task demands.

PubMed

Beshel, Jennifer; Kopell, Nancy; Kay, Leslie M

2007-08-01

Fast oscillations in neural assemblies have been proposed as a mechanism to facilitate stimulus representation in a variety of sensory systems across animal species. In the olfactory system, intervention studies suggest that oscillations in the gamma frequency range play a role in fine odor discrimination. However, there is still no direct evidence that such oscillations are intrinsically altered in intact systems to aid in stimulus disambiguation. Here we show that gamma oscillatory power in the rat olfactory bulb during a two-alternative choice task is modulated in the intact system according to task demands with dramatic increases in gamma power during discrimination of molecularly similar odorants in contrast to dissimilar odorants. This elevation in power evolves over the course of criterion performance, is specific to the gamma frequency band (65-85 Hz), and is independent of changes in the theta or beta frequency band range. Furthermore, these high amplitude gamma oscillations are restricted to the olfactory bulb, such that concurrent piriform cortex recordings show no evidence of enhanced gamma power during these high-amplitude events. Our results display no modulation in the power of beta oscillations (15-28 Hz) shown previously to increase with odor learning in a Go/No-go task, and we suggest that the oscillatory profile of the olfactory system may be influenced by both odor discrimination demands and task type. The results reported here indicate that enhancement of local gamma power may reflect a switch in the dynamics of the system to a strategy that optimizes stimulus resolution when input signals are ambiguous.

Dissecting neural pathways for forgetting in Drosophila olfactory aversive memory

PubMed Central

Shuai, Yichun; Hirokawa, Areekul; Ai, Yulian; Zhang, Min; Li, Wanhe; Zhong, Yi

2015-01-01

Recent studies have identified molecular pathways driving forgetting and supported the notion that forgetting is a biologically active process. The circuit mechanisms of forgetting, however, remain largely unknown. Here we report two sets of Drosophila neurons that account for the rapid forgetting of early olfactory aversive memory. We show that inactivating these neurons inhibits memory decay without altering learning, whereas activating them promotes forgetting. These neurons, including a cluster of dopaminergic neurons (PAM-β′1) and a pair of glutamatergic neurons (MBON-γ4>γ1γ2), terminate in distinct subdomains in the mushroom body and represent parallel neural pathways for regulating forgetting. Interestingly, although activity of these neurons is required for memory decay over time, they are not required for acute forgetting during reversal learning. Our results thus not only establish the presence of multiple neural pathways for forgetting in Drosophila but also suggest the existence of diverse circuit mechanisms of forgetting in different contexts. PMID:26627257

A program for undergraduate research into the mechanisms of sensory coding and memory decay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Calin-Jageman, R J

This is the final technical report for this DOE project, entitltled "A program for undergraduate research into the mechanisms of sensory coding and memory decay". The report summarizes progress on the three research aims: 1) to identify phyisological and genetic correlates of long-term habituation, 2) to understand mechanisms of olfactory coding, and 3) to foster a world-class undergraduate neuroscience program. Progress on the first aim has enabled comparison of learning-regulated transcripts across closely related learning paradigms and species, and results suggest that only a small core of transcripts serve truly general roles in long-term memory. Progress on the second aimmore » has enabled testing of several mutant phenotypes for olfactory behaviors, and results show that responses are not fully consistent with the combinitoral coding hypothesis. Finally, 14 undergraduate students participated in this research, the neuroscience program attracted extramural funding, and we completed a successful summer program to enhance transitions for community-college students into 4-year colleges to persue STEM fields.« less

An engram found? Evaluating the evidence from fruit flies.

PubMed

Gerber, Bertram; Tanimoto, Hiromu; Heisenberg, Martin

2004-12-01

Is it possible to localize a memory trace to a subset of cells in the brain? If so, it should be possible to show: first, that neuronal plasticity occurs in these cells. Second, that neuronal plasticity in these cells is sufficient for memory. Third, that neuronal plasticity in these cells is necessary for memory. Fourth, that memory is abolished if these cells cannot provide output during testing. And fifth, that memory is abolished if these cells cannot receive input during training. With regard to olfactory learning in flies, we argue that the notion of the olfactory memory trace being localized to the Kenyon cells of the mushroom bodies is a reasonable working hypothesis.

A Subtype of Olfactory Bulb Interneurons Is Required for Odor Detection and Discrimination Behaviors.

PubMed

Takahashi, Hiroo; Ogawa, Yoichi; Yoshihara, Sei-Ichi; Asahina, Ryo; Kinoshita, Masahito; Kitano, Tatsuro; Kitsuki, Michiko; Tatsumi, Kana; Okuda, Mamiko; Tatsumi, Kouko; Wanaka, Akio; Hirai, Hirokazu; Stern, Peter L; Tsuboi, Akio

2016-08-03

Neural circuits that undergo reorganization by newborn interneurons in the olfactory bulb (OB) are necessary for odor detection and discrimination, olfactory memory, and innate olfactory responses, including predator avoidance and sexual behaviors. The OB possesses many interneurons, including various types of granule cells (GCs); however, the contribution that each type of interneuron makes to olfactory behavioral control remains unknown. Here, we investigated the in vivo functional role of oncofetal trophoblast glycoprotein 5T4, a regulator for dendritic arborization of 5T4-expressing GCs (5T4 GCs), the level of which is reduced in the OB of 5T4 knock-out (KO) mice. Electrophysiological recordings with acute OB slices indicated that external tufted cells (ETCs) can be divided into two types, bursting and nonbursting. Optogenetic stimulation of 5T4 GCs revealed their connection to both bursting and nonbursting ETCs, as well as to mitral cells (MCs). Interestingly, nonbursting ETCs received fewer inhibitory inputs from GCs in 5T4 KO mice than from those in wild-type (WT) mice, whereas bursting ETCs and MCs received similar inputs in both mice. Furthermore, 5T4 GCs received significantly fewer excitatory inputs in 5T4 KO mice. Remarkably, in olfactory behavior tests, 5T4 KO mice had higher odor detection thresholds than the WT, as well as defects in odor discrimination learning. Therefore, the loss of 5T4 attenuates inhibitory inputs from 5T4 GCs to nonbursting ETCs and excitatory inputs to 5T4 GCs, contributing to disturbances in olfactory behavior. Our novel findings suggest that, among the various types of OB interneurons, the 5T4 GC subtype is required for odor detection and discrimination behaviors. Neuronal circuits in the brain include glutamatergic principal neurons and GABAergic interneurons. Although the latter is a minority cell type, they are vital for normal brain function because they regulate the activity of principal neurons. If interneuron function is impaired, brain function may be damaged, leading to behavior disorder. The olfactory bulb (OB) possesses various types of interneurons, including granule cells (GCs); however, the contribution that each type of interneuron makes to the control of olfactory behavior remains unknown. Here, we analyzed electrophysiologically and behaviorally the function of oncofetal trophoblast glycoprotein 5T4, a regulator for dendritic branching in OB GCs. We found that, among the various types of OB interneuron, the 5T4 GC subtype is required for odor detection and odor discrimination behaviors. Copyright © 2016 the authors 0270-6474/16/368211-18$15.00/0.

Roles of Octopamine and Dopamine Neurons for Mediating Appetitive and Aversive Signals in Pavlovian Conditioning in Crickets

PubMed Central

Mizunami, Makoto; Matsumoto, Yukihisa

2017-01-01

Revealing neural systems that mediate appetite and aversive signals in associative learning is critical for understanding the brain mechanisms controlling adaptive behavior in animals. In mammals, it has been shown that some classes of dopamine neurons in the midbrain mediate prediction error signals that govern the learning process, whereas other classes of dopamine neurons control execution of learned actions. In this review, based on the results of our studies on Pavlovian conditioning in the cricket Gryllus bimaculatus and by referring to the findings in honey bees and fruit-flies, we argue that comparable aminergic systems exist in the insect brain. We found that administrations of octopamine (the invertebrate counterpart of noradrenaline) and dopamine receptor antagonists impair conditioning to associate an olfactory or visual conditioned stimulus (CS) with water or sodium chloride solution (appetitive or aversive unconditioned stimulus, US), respectively, suggesting that specific octopamine and dopamine neurons mediate appetitive and aversive signals, respectively, in conditioning in crickets. These findings differ from findings in fruit-flies. In fruit-flies, appetitive and aversive signals are mediated by different dopamine neuron subsets, suggesting diversity in neurotransmitters mediating appetitive signals in insects. We also found evidences of “blocking” and “auto-blocking” phenomena, which suggested that the prediction error, the discrepancy between actual US and predicted US, governs the conditioning in crickets and that octopamine neurons mediate prediction error signals for appetitive US. Our studies also showed that activations of octopamine and dopamine neurons are needed for the execution of an appetitive conditioned response (CR) and an aversive CR, respectively, and we, thus, proposed that these neurons mediate US prediction signals that drive appetitive and aversive CRs. Our findings suggest that the basic principles of functioning of aminergic systems in associative learning, i.e., to transmit prediction error signals for conditioning and to convey US prediction signals for execution of CR, are conserved among insects and mammals, on account of the fact that the organization of the insect brain is much simpler than that of the mammalian brain. Further investigation of aminergic systems that govern associative learning in insects should lead to a better understanding of commonalities and diversities of computational rules underlying associative learning in animals. PMID:29311961

Roles of Octopamine and Dopamine Neurons for Mediating Appetitive and Aversive Signals in Pavlovian Conditioning in Crickets.

PubMed

Mizunami, Makoto; Matsumoto, Yukihisa

2017-01-01

Revealing neural systems that mediate appetite and aversive signals in associative learning is critical for understanding the brain mechanisms controlling adaptive behavior in animals. In mammals, it has been shown that some classes of dopamine neurons in the midbrain mediate prediction error signals that govern the learning process, whereas other classes of dopamine neurons control execution of learned actions. In this review, based on the results of our studies on Pavlovian conditioning in the cricket Gryllus bimaculatus and by referring to the findings in honey bees and fruit-flies, we argue that comparable aminergic systems exist in the insect brain. We found that administrations of octopamine (the invertebrate counterpart of noradrenaline) and dopamine receptor antagonists impair conditioning to associate an olfactory or visual conditioned stimulus (CS) with water or sodium chloride solution (appetitive or aversive unconditioned stimulus, US), respectively, suggesting that specific octopamine and dopamine neurons mediate appetitive and aversive signals, respectively, in conditioning in crickets. These findings differ from findings in fruit-flies. In fruit-flies, appetitive and aversive signals are mediated by different dopamine neuron subsets, suggesting diversity in neurotransmitters mediating appetitive signals in insects. We also found evidences of "blocking" and "auto-blocking" phenomena, which suggested that the prediction error, the discrepancy between actual US and predicted US, governs the conditioning in crickets and that octopamine neurons mediate prediction error signals for appetitive US. Our studies also showed that activations of octopamine and dopamine neurons are needed for the execution of an appetitive conditioned response (CR) and an aversive CR, respectively, and we, thus, proposed that these neurons mediate US prediction signals that drive appetitive and aversive CRs. Our findings suggest that the basic principles of functioning of aminergic systems in associative learning, i.e., to transmit prediction error signals for conditioning and to convey US prediction signals for execution of CR, are conserved among insects and mammals, on account of the fact that the organization of the insect brain is much simpler than that of the mammalian brain. Further investigation of aminergic systems that govern associative learning in insects should lead to a better understanding of commonalities and diversities of computational rules underlying associative learning in animals.

[Evaluating function and disorders of smell].

PubMed

Herberhold, C

1975-01-01

Firstly the review deals with the olfactometry after discussing the olfactory and trigeminal sensitivity of the sense of smell. The term olfactometry will be newly fixed concerning the present problems of odor analysis. Under clinical aspects the methods of subjective olfactometry are discussed and valued. Olfactory tests basing on registering several psychosomatic reflexes (e.g. cardial and/or respiratory frequencies) cannot be described as "objective". Rather methods are objective which record poststimulatory electrophysiological events at different steps of olfactory pathways. The electric response olfactometry representing a cortical evoked so-called twin-potential containing equivalents for trigeminal and olfactory sense activity starts to demonstrate its efficiency. At least a complete test of olfactory function today includes the rhinomanometry for recording ability in nasal odor transport capacity. In the second part are discussed the olfactory disorders with clinical importance. Air borne disorders are confronted with sensorineural, which again are divided in prebulbar, bulbar, and postbulbar ones so far as possible. Respiratory smell disorders depend on nasal ventilation and occur in nasal deformations, in abnormalities of respiratory pathways, in cases of foreign bodies, mucosal inflammations, tumors, intoxications and allergy. Sensorineural olfactory disorders can be attached to age, to malformations or idiopathic defects, inflammations of the olfactory-neural apparatus, head injuries, brain tumors, metabolic or endocrinological diseases. Furthermore often they are accompanied with neurological and psychiatric diseases or professional and chemical intoxications and/or iatrogenic influences. The poor therapeutical possibilities are demonstrated as far as possible. Finally the experting problems in olfactory disorders are delineated, at which the evidence of objective olfactometry can be distincted.

Predictors of quality of life outcomes in chronic rhinosinusitis after sinus surgery.

PubMed

Katotomichelakis, Michael; Simopoulos, Efthimios; Tripsianis, Gregory; Balatsouras, Dimitrios; Danielides, Gerasimos; Kourousis, Christos; Livaditis, Miltos; Danielides, Vassilios

2014-04-01

The predictive value of olfaction for quality of life (QoL) recovery after endoscopic sinus surgery (ESS) in chronic rhinosinusitis (CRS) is still underestimated. The aim of this study was to explore the proportion of patients suffering from CRS who experience clinically significant QoL improvement after ESS and identify pre-operative clinical phenotypes that best predict surgical outcomes for QoL, focusing mainly on the role of patients' olfaction. One hundred eleven patients following ESS for CRS and 48 healthy subjects were studied. Olfactory function was expressed by the combined "Threshold Discrimination Identification" score using "Sniffin' sticks" test pre-treatment and 12 months after treatment. All subjects completed validated, widely used QoL questionnaires, specific for olfaction (Questionnaire of Olfactory Deficits: QOD), for assessing psychology (Beck Depression Inventory: BDI) and for general health (Short Form-36: SF-36). Statistically significant improvement of olfactory function by 41.8% and of all QoL questionnaires scores (all p < 0.001) was observed on the 12-month follow-up examination. Clinically significant improvement for QoL was measured in a proportion of 56.8% of patients on QOD, 64.9% on SF-36 and 49.5% on BDI scales results. Although olfactory dysfunction, nasal polyps, female gender, high socio-economic status and non-smoking habits were significantly associated with better QoL results, multivariate logistic regression analysis revealed that only olfactory dysfunction and nasal polyps were independent predictors significantly associated with higher likelihood of clinically significant improvement in all QoL questionnaire results. Olfactory dysfunction and nasal polyps were independent pre-operative predictors for surgical outcomes with regard to QoL results.

Olfactory dysfunction, olfactory bulb pathology and urban air pollution

PubMed Central

Calderón-Garcidueñas, Lilian; Franco-Lira, Maricela; Henríquez-Roldán, Carlos; Osnaya, Norma; González-Maciel, Angelica; Reynoso-Robles, Rafael; Villarreal-Calderon, Rafael; Herritt, Lou; Brooks, Diane; Keefe, Sheyla; Palacios-Moreno, Juan; Villarreal-Calderon, Rodolfo; Torres-Jardón, Ricardo; Medina-Cortina, Humberto; Delgado-Chávez, Ricardo; Aiello-Mora, Mario; Maronpot, Robert R.; Doty, Richard L

2010-01-01

Mexico City (MC) residents are exposed to severe air pollution and exhibit olfactory bulb inflammation. We compared the olfactory function of individuals living under conditions of extreme air pollution to that of controls from a relatively clean environment and explore associations between olfaction scores, apolipoprotein E (APOE) status, and pollution exposure. The olfactory bulbs (OBs) of 35 MC and 9 controls 20.8 ± 8.5 y were assessed by light and electron microscopy. The University of Pennsylvania Smell Identification Test (UPSIT) was administered to 62 MC / 25 controls 21.2 ±2.7 y. MC subjects had significantly lower UPSIT scores: 34.24 ± 0.42 versus controls 35.76 ± 0.40, p=0.03. Olfaction deficits were present in 35.5% MC and 12% of controls. MC APOE ε 4 carriers failed 2.4 ± 0.54 items in the 10-item smell identification scale from the UPSIT related to Alzheimer's disease, while APOE 2/3 and 3/3 subjects failed 1.36 ± 0.16 items, p = 0.01. MC residents exhibited OB endothelial hyperplasia, neuronal accumulation of particles (2/35), and immunoreactivity to beta amyloid βA42 (29/35) and/or α-synuclein (4/35) in neurons, glial cells and/or blood vessels. Ultrafine particles were present in OBs endothelial cytoplasm and basement membranes. Control OBs were unremarkable. Air pollution exposure is associated with olfactory dysfunction and OB pathology, APOE 4 may confer greater susceptibility to such abnormalities, and ultrafine particles could play a key role in the OB pathology. This study contributes to our understanding of the influences of air pollution on olfaction and its potential contribution to neurodegeneration. PMID:19297138

Protein tyrosine phosphatase receptor type R deficient mice exhibit increased exploration in a new environment and impaired novel object recognition memory.

PubMed

Erkens, Mirthe; Bakker, Brenda; van Duijn, Lucette M; Hendriks, Wiljan J A J; Van der Zee, Catharina E E M

2014-05-15

Mouse gene Ptprr encodes multiple protein tyrosine phosphatase receptor type R (PTPRR) isoforms that negatively regulate mitogen-activated protein kinase (MAPK) signaling pathways. In the mouse brain, PTPRR proteins are expressed in cerebellum, olfactory bulb, hippocampus, amygdala and perirhinal cortex but their precise role in these regions remains to be determined. Here, we evaluated phenotypic consequences of loss of PTPRR activity and found that basal smell was normal for Ptprr(-/-) mice. Also, spatial learning and fear-associated contextual learning were unaffected. PTPRR deficiency, however, resulted in impaired novel object recognition and a striking increase in exploratory activity in a new environment. The data corroborate the importance of proper control of MAPK signaling in cerebral functions and put forward PTPRR as a novel target to modulate synaptic processes. Copyright © 2014 Elsevier B.V. All rights reserved.

Honeybees Learn Odour Mixtures via a Selection of Key Odorants

PubMed Central

Reinhard, Judith; Sinclair, Michael; Srinivasan, Mandyam V.; Claudianos, Charles

2010-01-01

Background The honeybee has to detect, process and learn numerous complex odours from her natural environment on a daily basis. Most of these odours are floral scents, which are mixtures of dozens of different odorants. To date, it is still unclear how the bee brain unravels the complex information contained in scent mixtures. Methodology/Principal Findings This study investigates learning of complex odour mixtures in honeybees using a simple olfactory conditioning procedure, the Proboscis-Extension-Reflex (PER) paradigm. Restrained honeybees were trained to three scent mixtures composed of 14 floral odorants each, and then tested with the individual odorants of each mixture. Bees did not respond to all odorants of a mixture equally: They responded well to a selection of key odorants, which were unique for each of the three scent mixtures. Bees showed less or very little response to the other odorants of the mixtures. The bees' response to mixtures composed of only the key odorants was as good as to the original mixtures of 14 odorants. A mixture composed of the other, non-key-odorants elicited a significantly lower response. Neither an odorant's volatility or molecular structure, nor learning efficiencies for individual odorants affected whether an odorant became a key odorant for a particular mixture. Odorant concentration had a positive effect, with odorants at high concentration likely to become key odorants. Conclusions/Significance Our study suggests that the brain processes complex scent mixtures by predominantly learning information from selected key odorants. Our observations on key odorant learning lend significant support to previous work on olfactory learning and mixture processing in honeybees. PMID:20161714

Visualization and Quantification of Nasal and Olfactory Deposition in a Sectional Adult Nasal Airway Cast.

PubMed

Xi, Jinxiang; Yuan, Jiayao Eddie; Zhang, Yu; Nevorski, Dannielle; Wang, Zhaoxuan; Zhou, Yue

2016-06-01

To compare drug deposition in the nose and olfactory region with different nasal devices and administration techniques. A Sar-Gel based colorimetry method will be developed to quantify local deposition rates. A sectional nasal airway cast was developed based on an MRI-based nasal airway model to visualize deposition patterns and measure regional dosages. Four nasal spray pumps and four nebulizers were tested with both standard and point-release administration techniques. Delivered dosages were measured using a high-precision scale. The colorimetry correlation for deposited mass was developed via image processing in Matlab and its performance was evaluated through comparison to experimental measurements. Results show that the majority of nasal spray droplets deposited in the anterior nose while only a small fraction (less than 4.6%) reached the olfactory region. For all nebulizers considered, more droplets went beyond the nasal valve, leading to distinct deposition patterns as a function of both the nebulizer type (droplet size and initial speed) and inhalation flow rate. With the point-release administration, up to 9.0% (±1.9%) of administered drugs were delivered to the olfactory region and 15.7 (±2.4%) to the upper nose using Pari Sinus. Standard nasal devices are inadequate to deliver clinically significant olfactory dosages without excess drug losses in other nasal epitheliums. The Sar-Gel based colorimetry method appears to provide a simple and practical approach to visualize and quantify regional deposition.

Sad man's nose: Emotion induction and olfactory perception.

PubMed

Flohr, Elena L R; Erwin, Elena; Croy, Ilona; Hummel, Thomas

2017-03-01

Emotional and olfactory processing is frequently shown to be closely linked both anatomically and functionally. Depression, a disease closely related to the emotional state of sadness, has been shown to be associated with a decrease in olfactory sensitivity. The present study focuses on the state of sadness in n = 31 healthy subjects in order to investigate the specific contribution of this affective state in the modulation of olfactory processing. A sad or indifferent affective state was induced using 2 movies that were presented on 2 separate days. Afterward, chemosensory-evoked potentials were recorded after stimulation with an unpleasant (hydrogen sulfide: "rotten eggs") or a pleasant (phenyl ethyl alcohol: "rose") odorant. Latencies of N1 and P2 peaks were longer after induction of the sad affective state. Additionally, amplitudes were lower in a sad affective state when being stimulated with the unpleasant odorant. Processing of olfactory input has thus been reduced under conditions of the sad affective state. We argue that the affective state per se could at least partially account for the reduced olfactory sensitivity in depressed patients. To our knowledge, the present study is the first to show influence of affective state on chemosensory event-related potentials. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Olfactory identification deficits and associated response inhibition in obsessive-compulsive disorder: on the scent of the orbitofronto-striatal model.

PubMed

Bersani, Giuseppe; Quartini, Adele; Ratti, Flavia; Pagliuca, Giulio; Gallo, Andrea

2013-11-30

Olfactory identification ability implicates the integrity of the orbitofrontal cortex (OFC). The fronto-striatal circuits including the OFC have been involved in the neuropathology of Obsessive Compulsive Disorder (OCD). However, only a few studies have examined olfactory function in patients with OCD. The Brief Smell Identification Test (B-SIT) and tests from the Cambridge Neuropsychological Automated Battery (CANTAB) were administered to 25 patients with OCD and to 21 healthy matched controls. OCD patients showed a significant impairment in olfactory identification ability as well as widely distributed cognitive deficits in visual memory, executive functions, attention, and response inhibition. The degree of behavioural impairment on motor impulsivity (prolonged response inhibition Stop-Signal Reaction Time) strongly correlated with the B-SIT score. Our study is the first to indicate a shared OFC pathological neural substrate underlying olfactory identification impairment, impulsivity, and OCD. Deficits in visual memory, executive functions and attention further indicate that regions outside of the orbitofronto-striatal loop may be involved in this disorder. Such results may help delineate the clinical complexity of OCD and support more targeted investigations and interventions. In this regard, research on the potential diagnostic utility of olfactory identification deficits in the assessment of OCD would certainly be useful. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

The olfactory system as the gateway to the neural correlates of consciousness

PubMed Central

Merrick, Christina; Godwin, Christine A.; Geisler, Mark W.; Morsella, Ezequiel

2014-01-01

How consciousness is generated by the nervous system remains one of the greatest mysteries in science. Investigators from diverse fields have begun to unravel this puzzle by contrasting conscious and unconscious processes. In this way, it has been revealed that the two kinds of processes differ in terms of the underlying neural events and associated cognitive mechanisms. We propose that, for several reasons, the olfactory system provides a unique portal through which to examine this contrast. For this purpose, the olfactory system is beneficial in terms of its (a) neuroanatomical aspects, (b) phenomenological and cognitive/mechanistic properties, and (c) neurodynamic (e.g., brain oscillations) properties. In this review, we discuss how each of these properties and aspects of the olfactory system can illuminate the contrast between conscious and unconscious processing in the brain. We conclude by delineating the most fruitful avenues of research and by entertaining hypotheses that, in order for an olfactory content to be conscious, that content must participate in a network that is large-scale, both in terms of the neural systems involved and the scope of information integration. PMID:24454300

Histological and Lectin Histochemical Studies on the Olfactory and Respiratory Mucosae of the Sheep

PubMed Central

IBRAHIM, Dalia; NAKAMUTA, Nobuaki; TANIGUCHI, Kazumi; YAMAMOTO, Yoshio; TANIGUCHI, Kazuyuki

2013-01-01

ABSTRACT The olfactory and respiratory mucosae of the Corriedale sheep were examined using lectin histochemistry in order to clarify the histochemical and glycohistochemical differences between these two tissues. The olfactory epithelium was stained with 13 lectins out of 21 lectins examined, while the respiratory epithelium was positive to 16 lectins. The free border of both of the olfactory and respiratory epithelia was stained with 12 lectins: Wheat germ agglutinin (WGA), succinylated-wheat germ agglutinin (s-WGA), Lycopersicon esculentum lectin (LEL), Solanum tuberosum lectin (STL), Datura stramonium lectin (DSL), Soybean agglutinin (SBA), Bandeiraea simplicifolia lectin-I (BSL-I), Ricinus communis agglutinin-I (RCA-120), Erythrina cristagalli lectin (ECL), Concanavalin A (Con A), Phaseolus vulgaris agglutinin-E (PHA-E) and Phaseolus vulgaris agglutinin-L (PHA-L). The associated glands of the olfactory mucosa, Bowman’s glands, were stained with 13 lectins. While both the goblet cells and mucous nasal glands were stained with 8 lectins; five of them (WGA, s-WGA, STL, Vicia villosa agglutinin (VVA) and ECL) were mutually positive among the Bowman’s glands, mucous nasal glands and the goblet cells. These findings indicate that the glycohistochemical characteristics of the free borders of both olfactory and respiratory epithelia are similar to each other, suggesting that secretions from the Bowman’s glands and those of the goblet cells and mucous nasal glands are partially exchanged between the surface of two epithelia to contribute the functions of the respiratory epithelium and the olfactory receptor cells, respectively. PMID:24200894

Concise review: Patient-derived olfactory stem cells: new models for brain diseases.

PubMed

Mackay-Sim, Alan

2012-11-01

Traditional models of brain diseases have had limited success in driving candidate drugs into successful clinical translation. This has resulted in large international pharmaceutical companies moving out of neuroscience research. Cells are not brains, obviously, but new patient-derived stem models have the potential to elucidate cell biological aspects of brain diseases that are not present in worm, fly, or rodent models, the work horses of disease investigations and drug discovery. Neural stem cells are present in the olfactory mucosa, the organ of smell in the nose. Patient-derived olfactory mucosa has demonstrated disease-associated differences in a variety of brain diseases and recently olfactory mucosa stem cells have been generated from patients with schizophrenia, Parkinson's disease, and familial dysautonomia. By comparison with cells from healthy controls, patient-derived olfactory mucosa stem cells show disease-specific alterations in gene expression and cell functions including: a shorter cell cycle and faster proliferation in schizophrenia, oxidative stress in Parkinson's disease, and altered cell migration in familial dysautonomia. Olfactory stem cell cultures thus reveal patient-control differences, even in complex genetic diseases such as schizophrenia and Parkinson's disease, indicating that multiple genes of small effect can converge on shared cell signaling pathways to present as a disease-specific cellular phenotype. Olfactory mucosa stem cells can be maintained in homogeneous cultures that allow robust and repeatable multiwell assays suitable for screening libraries of drug candidate molecules. Copyright © 2012 AlphaMed Press.

Enhanced olfactory sensitivity in autism spectrum conditions.

PubMed

Ashwin, Chris; Chapman, Emma; Howells, Jessica; Rhydderch, Danielle; Walker, Ian; Baron-Cohen, Simon

2014-01-01

People with autism spectrum conditions (ASC) report heightened olfaction. Previous sensory experiments in people with ASC have reported hypersensitivity across visual, tactile, and auditory domains, but not olfaction. The aims of the present study were to investigate olfactory sensitivity in ASC, and to test the association of sensitivity to autistic traits. We recruited 17 adult males diagnosed with ASC and 17 typical adult male controls and tested their olfactory sensitivity using the Alcohol Sniff Test (AST), a standardised clinical evaluation of olfactory detection. The AST involves varying the distance between subject and stimulus until an odour is barely detected. Participants with ASC also completed the Autism Spectrum Quotient (AQ) as a measure of autism traits. The ASC group detected the odour at a mean distance of 24.1 cm (SD =11.5) from the nose, compared to the control group, who detected it at a significantly shorter mean distance of 14.4 cm (SD =5.9). Detection distance was independent of age and IQ for both groups, but showed a significant positive correlation with autistic traits in the ASC group (r =0.522). This is the first experimental demonstration, as far as the authors are aware, of superior olfactory perception in ASC and showing that greater olfactory sensitivity is correlated with a higher number of autistic traits. This is consistent with results from previous findings showing hypersensitivity in other sensory domains and may help explain anecdotal and questionnaire accounts of heightened olfactory sensitivity in ASC. Results are discussed in terms of possible underlying neurophysiology.

Body Odor Trait Disgust Sensitivity Predicts Perception of Sweat Biosamples.

PubMed

Liuzza, Marco Tullio; Olofsson, Jonas K; Sabiniewicz, Agnieszka; Sorokowska, Agnieszka

2017-07-01

Body odors are potent triggers of disgust and regulate social behaviors in many species. The role of olfaction in disgust-associated behaviors has received scant attention in the research literature, in part because olfactory disgust assessments have required laboratory testing with odors. We have devised the "Body Odor Disgust Scale" (BODS) to facilitate research on olfactory disgust. In this study, we evaluated whether individual differences in BODS scores would be associated with the perception of disgust for sweat samples in a laboratory setting. Results show that BODS was a strong predictor of disgust ratings of sweat samples even when controlling for general disgust sensitivity. In contrast, odor intensity ratings were unrelated to BODS scores. Our findings suggest that the BODS scores reflect body odor disgust perception. The BODS scale might facilitate research on olfactory disgust responses and associated behaviors. © The Author 2017. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Learning performance and brain structure of artificially-reared honey bees fed with different quantities of food

PubMed Central

Spaethe, Johannes; Steffan-Dewenter, Ingolf; Härtel, Stephan

2017-01-01

Background Artificial rearing of honey bee larvae is an established method which enables to fully standardize the rearing environment and to manipulate the supplied diet to the brood. However, there are no studies which compare learning performance or neuroanatomic differences of artificially-reared (in-lab) bees in comparison with their in-hive reared counterparts. Methods Here we tested how different quantities of food during larval development affect body size, brain morphology and learning ability of adult honey bees. We used in-lab rearing to be able to manipulate the total quantity of food consumed during larval development. After hatching, a subset of the bees was taken for which we made 3D reconstructions of the brains using confocal laser-scanning microscopy. Learning ability and memory formation of the remaining bees was tested in a differential olfactory conditioning experiment. Finally, we evaluated how bees reared with different quantities of artificial diet compared to in-hive reared bees. Results Thorax and head size of in-lab reared honey bees, when fed the standard diet of 160 µl or less, were slightly smaller than hive bees. The brain structure analyses showed that artificially reared bees had smaller mushroom body (MB) lateral calyces than their in-hive counterparts, independently of the quantity of food they received. However, they showed the same total brain size and the same associative learning ability as in-hive reared bees. In terms of mid-term memory, but not early long-term memory, they performed even better than the in-hive control. Discussion We have demonstrated that bees that are reared artificially (according to the Aupinel protocol) and kept in lab-conditions perform the same or even better than their in-hive sisters in an olfactory conditioning experiment even though their lateral calyces were consistently smaller at emergence. The applied combination of experimental manipulation during the larval phase plus subsequent behavioral and neuro-anatomic analyses is a powerful tool for basic and applied honey bee research. PMID:29085743

Evidence that thyroid hormone induces olfactory cellular proliferation in salmon during a sensitive period for imprinting.

PubMed

Lema, Sean C; Nevitt, Gabrielle A

2004-09-01

Salmon have long been known to imprint and home to natal stream odors, yet the mechanisms driving olfactory imprinting remain obscure. The timing of imprinting is associated with elevations in plasma thyroid hormone levels, with possible effects on growth and proliferation of the peripheral olfactory system. Here, we begin to test this idea by determining whether experimentally elevated plasma levels of 3,5,3'-triiodothyronine (T(3)) influence cell proliferation as detected by the 5-bromo-2'-deoxyuridine (BrdU) cell birth-dating technique in the olfactory epithelium of juvenile coho salmon (Oncorhynchus kisutch). We also explore how natural fluctuations in thyroxine (T(4)) relate to proliferation in the epithelium during the parr-smolt transformation. In both studies, we found that BrdU labeled both single and clusters of mitotic cells. The total number of BrdU-labeled cells in the olfactory epithelium was significantly greater in fish with artificially elevated T(3) compared with placebo controls. This difference in proliferation was restricted to the basal region of the olfactory epithelium, where multipotent progenitor cells differentiate into olfactory receptor neurons. The distributions of mitotic cluster sizes differed significantly from a Poisson distribution for both T(3) and placebo treatments, suggesting that proliferation tends to be non-random. Over the course of the parr-smolt transformation, changes in the density of BrdU cells showed a positive relationship with natural fluctuations in plasma T(4). This relationship suggests that even small changes in thyroid activity can stimulate the proliferation of neural progenitor cells in the salmon epithelium. Taken together, our results establish a link between the thyroid hormone axis and measurable anatomical changes in the peripheral olfactory system.

Development of the terminal nerve system in the shark Scyliorhinus canicula.

PubMed

Quintana-Urzainqui, Idoia; Anadón, Ramón; Candal, Eva; Rodríguez-Moldes, Isabel

2014-01-01

The nervus terminalis (or terminal nerve) system was discovered in an elasmobranch species more than a century ago. Over the past century, it has also been recognized in other vertebrate groups, from agnathans to mammals. However, its origin, functions or relationship with the olfactory system are still under debate. Despite the abundant literature about the nervus terminalis system in adult elasmobranchs, its development has been overlooked. Studies in other vertebrates have reported newly differentiated neurons of the terminal nerve system migrating from the olfactory epithelium to the telencephalon as part of a 'migratory mass' of cells associated with the olfactory nerve. Whether the same occurs in developing elasmobranchs (adults showing anatomically separated nervus terminalis and olfactory systems) has not yet been determined. In this work we characterized for the first time the development of the terminal nerve and ganglia in an elasmobranch, the lesser spotted dogfish (Scyliorhinus canicula), by means of tract-tracing techniques combined with immunohistochemical markers for the terminal nerve (such as FMRF-amide peptide), for the developing components of the olfactory system (Gα0 protein, GFAP, Pax6), and markers for early postmitotic neurons (HuC/D) and migrating immature neurons (DCX). We discriminated between embryonic olfactory and terminal nerve systems and determined that both components may share a common origin in the migratory mass. We also localized the exact point where they split off near the olfactory nerve-olfactory bulb junction. The study of the development of the terminal nerve system in a basal gnathostome contributes to the knowledge of the ancestral features of this system in vertebrates, shedding light on its evolution and highlighting the importance of elasmobranchs for developmental and evolutionary studies. © 2014 S. Karger AG, Basel.

Non-motor parkinsonian pathology in aging A53T α-synuclein mice is associated with progressive synucleinopathy and altered enzymatic function.

PubMed

Farrell, Kaitlin F; Krishnamachari, Sesha; Villanueva, Ernesto; Lou, Haiyan; Alerte, Tshianda N M; Peet, Eloise; Drolet, Robert E; Perez, Ruth G

2014-02-01

Aging, the main risk factor for Parkinson's disease (PD), is associated with increased α-synuclein levels in substantia nigra pars compacta (SNc). Excess α-synuclein spurs Lewy-like pathology and dysregulates the activity of protein phosphatase 2A (PP2A). PP2A dephosphorylates many neuroproteins, including the catecholamine rate-limiting enzyme, tyrosine hydroxylase (TH). A loss of nigral dopaminergic neurons induces PD movement problems, but before those abnormalities occur, behaviors such as olfactory loss, anxiety, and constipation often manifest. Identifying mouse models with early PD behavioral changes could provide a model in which to test emerging therapeutic compounds. To this end, we evaluated mice expressing A53T mutant human (A53T) α-synuclein for behavior and α-synuclein pathology in olfactory bulb, adrenal gland, and gut. Aging A53T mice exhibited olfactory loss and anxiety that paralleled olfactory and adrenal α-synuclein aggregation. PP2A activity was also diminished in olfactory and adrenal tissues harboring insoluble α-synuclein. Low adrenal PP2A activity co-occurred with TH hyperactivity, making this the first study to link adrenal synucleinopathy to anxiety and catecholamine dysregulation. Aggregated A53T α-synuclein recombinant protein also had impaired stimulatory effects on soluble recombinant PP2A. Collectively, the data identify an excellent model in which to screen compounds for their ability to block the spread of α-synuclein pathology associated with pre-motor stages of PD. © 2013 The Authors. Journal of Neurochemistry published by John Wiley & Sons Ltd on behalf of The International Society for Neurochemistry.

Brain architecture of the largest living land arthropod, the Giant Robber Crab Birgus latro (Crustacea, Anomura, Coenobitidae): evidence for a prominent central olfactory pathway?

PubMed Central

2010-01-01

Background Several lineages within the Crustacea conquered land independently during evolution, thereby requiring physiological adaptations for a semi-terrestrial or even a fully terrestrial lifestyle. Birgus latro Linnaeus, 1767, the giant robber crab or coconut crab (Anomura, Coenobitidae), is the largest land-living arthropod and inhabits Indo-Pacific islands such as Christmas Island. B. latro has served as a model in numerous studies of physiological aspects related to the conquest of land by crustaceans. From an olfactory point of view, a transition from sea to land means that molecules need to be detected in gas phase instead of in water solution. Previous studies have provided physiological evidence that terrestrial hermit crabs (Coenobitidae) such as B. latro have a sensitive and well differentiated sense of smell. Here we analyze the brain, in particular the olfactory processing areas of B. latro, by morphological analysis followed by 3 D reconstruction and immunocytochemical studies of synaptic proteins and a neuropeptide. Results The primary and secondary olfactory centers dominate the brain of B. latro and together account for ca. 40% of the neuropil volume in its brain. The paired olfactory neuropils are tripartite and composed of more than 1,000 columnar olfactory glomeruli, which are radially arranged around the periphery of the olfactory neuropils. The glomeruli are innervated ca. 90,000 local interneurons and ca. 160,000 projection neurons per side. The secondary olfactory centers, the paired hemiellipsoid neuropils, are targeted by the axons of these olfactory projection neurons. The projection neuron axonal branches make contact to ca. 250.000 interneurons (per side) associated with the hemiellipsoid neuropils. The hemiellipsoid body neuropil is organized into parallel neuropil lamellae, a design that is quite unusual for decapod crustaceans. The architecture of the optic neuropils and areas associated with antenna two suggest that B. latro has visual and mechanosensory skills that are comparable to those of marine Crustacea. Conclusions In parallel to previous behavioral findings that B. latro has aerial olfaction, our results indicate that their central olfactory pathway is indeed most prominent. Similar findings from the closely related terrestrial hermit crab Coenobita clypeatus suggest that in Coenobitidae, olfaction is a major sensory modality processed by the brain, and that for these animals, exploring the olfactory landscape is vital for survival in their terrestrial habitat. Future studies on terrestrial members of other crustacean taxa such as Isopoda, Amphipoda, Astacida, and Brachyura will shed light on how frequently the establishment of an aerial sense of olfaction evolved in Crustacea during the transition from sea to land. Amounting to ca. 1,000,000, the numbers of interneurons that analyse the olfactory input in B. latro brains surpasses that in other terrestrial arthropods, as e.g. the honeybee Apis mellifera or the moth Manduca sexta, by two orders of magnitude suggesting that B. latro in fact is a land-living arthropod that has devoted a substantial amount of nervous tissue to the sense of smell. PMID:20831795

Olfactory Receptor Subgenomes Linked with Broad Ecological Adaptations in Sauropsida.

PubMed

Khan, Imran; Yang, Zhikai; Maldonado, Emanuel; Li, Cai; Zhang, Guojie; Gilbert, M Thomas P; Jarvis, Erich D; O'Brien, Stephen J; Johnson, Warren E; Antunes, Agostinho

2015-11-01

Olfactory receptors (ORs) govern a prime sensory function. Extant birds have distinct olfactory abilities, but the molecular mechanisms underlining diversification and specialization remain mostly unknown. We explored OR diversity in 48 phylogenetic and ecologically diverse birds and 2 reptiles (alligator and green sea turtle). OR subgenomes showed species- and lineage-specific variation related with ecological requirements. Overall 1,953 OR genes were identified in reptiles and 16,503 in birds. The two reptiles had larger OR gene repertoires (989 and 964 genes, respectively) than birds (182-688 genes). Overall, birds had more pseudogenes (7,855) than intact genes (1,944). The alligator had significantly more functional genes than sea turtle, likely because of distinct foraging habits. We found rapid species-specific expansion and positive selection in OR14 (detects hydrophobic compounds) in birds and in OR51 and OR52 (detect hydrophilic compounds) in sea turtle, suggestive of terrestrial and aquatic adaptations, respectively. Ecological partitioning among birds of prey, water birds, land birds, and vocal learners showed that diverse ecological factors determined olfactory ability and influenced corresponding olfactory-receptor subgenome. OR5/8/9 was expanded in predatory birds and alligator, suggesting adaptive specialization for carnivory. OR families 2/13, 51, and 52 were correlated with aquatic adaptations (water birds), OR families 6 and 10 were more pronounced in vocal-learning birds, whereas most specialized land birds had an expanded OR family 14. Olfactory bulb ratio (OBR) and OR gene repertoire were correlated. Birds that forage for prey (carnivores/piscivores) had relatively complex OBR and OR gene repertoires compared with modern birds, including passerines, perhaps due to highly developed cognitive capacities facilitating foraging innovations. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Individual significance of olfaction: development of a questionnaire.

PubMed

Croy, Ilona; Buschhüter, Dorothee; Seo, Han-Seok; Negoias, Simona; Hummel, Thomas

2010-01-01

Clinical experience shows that the individual significance of olfactory function varies between subjects. In order to estimate these individual differences we developed a questionnaire to study the subjective importance of the sense of smell. Questions were arranged within three subscales: association with olfactory sensations, application of the sense of smell, and the readiness to draw consequences from the olfactory perception. The questionnaire was shown to be time efficient, suitable for normosmic subjects and patients with hyposmia or anosmia. It exhibited a good internal reliability (Cronbach's Alpha = 0.77). First results in 123 subjects indicate that the subjective importance of the sense of smell stays at the same level throughout life-span despite of a decreased olfactory sensitivity. Furthermore, women reported a higher importance of olfaction. It is hoped that this questionnaire will contribute to clarify, for example, cross-cultural differences in the perception of odours.

Direct neural pathways convey distinct visual information to Drosophila mushroom bodies

PubMed Central

Vogt, Katrin; Aso, Yoshinori; Hige, Toshihide; Knapek, Stephan; Ichinose, Toshiharu; Friedrich, Anja B; Turner, Glenn C; Rubin, Gerald M; Tanimoto, Hiromu

2016-01-01

Previously, we demonstrated that visual and olfactory associative memories of Drosophila share mushroom body (MB) circuits (Vogt et al., 2014). Unlike for odor representation, the MB circuit for visual information has not been characterized. Here, we show that a small subset of MB Kenyon cells (KCs) selectively responds to visual but not olfactory stimulation. The dendrites of these atypical KCs form a ventral accessory calyx (vAC), distinct from the main calyx that receives olfactory input. We identified two types of visual projection neurons (VPNs) directly connecting the optic lobes and the vAC. Strikingly, these VPNs are differentially required for visual memories of color and brightness. The segregation of visual and olfactory domains in the MB allows independent processing of distinct sensory memories and may be a conserved form of sensory representations among insects. DOI: http://dx.doi.org/10.7554/eLife.14009.001 PMID:27083044

Quantitative comparative analysis of the nasal chemosensory organs of anurans during larval development and metamorphosis highlights the relative importance of chemosensory subsystems in the group.

PubMed

Jungblut, Lucas David; Reiss, John O; Paz, Dante A; Pozzi, Andrea G

2017-09-01

The anuran peripheral olfactory system is composed of a number of subsystems, represented by distinct neuroepithelia. These include the main olfactory epithelium and vomeronasal organ (found in most tetrapods) and three specialized epithelia of anurans: the buccal-exposed olfactory epithelium of larvae, and the olfactory recess and middle chamber epithelium of postmetamorphic animals. To better characterize the developmental changes in these subsystems across the life cycle, morphometric changes of the nasal chemosensory organs during larval development and metamorphosis were analyzed in three different anuran species (Rhinella arenarum, Hypsiboas pulchellus, and Xenopus laevis). We calculated the volume of the nasal chemosensory organs by measuring the neuroepithelial area from serial histological sections at four different stages. In larvae, the vomeronasal organ was relatively reduced in R. arenarum compared with the other two species; the buccal-exposed olfactory epithelium was absent in X. laevis, and best developed in H. pulchellus. In postmetamorphic animals, the olfactory epithelium (air-sensitive organ) was relatively bigger in terrestrial species (R. arenarum and H. pulchellus), whereas the vomeronasal and the middle chamber epithelia (water-sensitive organs) was best developed in X. laevis. A small olfactory recess (likely homologous with the middle chamber epithelium) was found in R. arenarum juveniles, but not in H. pulchellus. These results support the association of the vomeronasal and middle chamber epithelia with aquatic olfaction, as seen by their enhanced development in the secondarily aquatic juveniles of X. laevis. They also support a role for the larval buccal-exposed olfactory epithelium in assessment of oral contents: it was absent in X. laevis, an obligate suspension feeder, while present in the two grazing species. These initial quantitative results give, for the first time, insight into the functional importance of the peripheral olfactory subsystems across the anuran life cycle. © 2017 Wiley Periodicals, Inc.

Interhemispheric EEG differences in olfactory bulbectomized rats with different cognitive abilities and brain beta-amyloid levels.

PubMed

Bobkova, Natalia; Vorobyov, Vasily; Medvinskaya, Natalia; Aleksandrova, Irina; Nesterova, Inna

2008-09-26

Alterations in electroencephalogram (EEG) asymmetry and deficits in interhemispheric integration of information have been shown in patients with Alzheimer's disease (AD). However, no direct evidence of an association between EEG asymmetry, morphological markers in the brain, and cognition was found either in AD patients or in AD models. In this study we used rats with bilateral olfactory bulbectomy (OBX) as one of the AD models and measured their learning/memory abilities, brain beta-amyloid levels and EEG spectra in symmetrical frontal and occipital cortices. One year after OBX or sham-surgery, the rats were tested with the Morris water paradigm and assigned to three groups: sham-operated rats, SO, and OBX rats with virtually normal, OBX(+), or abnormal, OBX(-), learning (memory) abilities. In OBX vs. SO, the theta EEG activity was enhanced to a higher extent in the right frontal cortex and in the left occipital cortex. This produced significant interhemispheric differences in the frontal cortex of the OBX(-) rats and in the occipital cortex of both OBX groups. The beta1 EEG asymmetry in SO was attenuated in OBX(+) and completely eliminated in OBX(-). OBX produced highly significant beta2 EEG decline in the right frontal cortex, with OBX(-)>OBX(+) rank order of strength. The beta-amyloid level, examined by post-mortem immunological DOT-analysis in the cortex-hippocampus samples, was about six-fold higher in OBX(-) than in SO, but significantly less (enhanced by 82% vs. SO) in OBX(+) than in OBX(-). The involvement of the brain mediatory systems in the observed EEG asymmetry differences is discussed.

Mice with genetic deletion of the heparin-binding growth factor midkine exhibit early preclinical features of Parkinson's disease.

PubMed

Prediger, Rui D S; Rojas-Mayorquin, Argelia E; Aguiar, Aderbal S; Chevarin, Caroline; Mongeau, Raymond; Hamon, Michel; Lanfumey, Laurence; Del Bel, Elaine; Muramatsu, Hisako; Courty, José; Raisman-Vozari, Rita

2011-08-01

There is considerable evidence showing that the neurodegenerative processes that lead to sporadic Parkinson's disease (PD) begin many years before the appearance of the characteristic motor symptoms and that impairments in olfactory, cognitive and motor functions are associated with time-dependent disruption of dopaminergic neurotransmission in different brain areas. Midkine is a 13-kDa retinoic acid-induced heparin-binding growth factor involved in many biological processes in the central nervous system such as cell migration, neurogenesis and tissue repair. The abnormal midkine expression may be associated with neurochemical dysfunction in the dopaminergic system and cognitive impairments in rodents. Here, we employed adult midkine knockout mice (Mdk(-/-)) to further investigate the relevance of midkine in dopaminergic neurotransmission and in olfactory, cognitive and motor functions. Mdk(/-) mice displayed pronounced impairments in their olfactory discrimination ability and short-term social recognition memory with no gross motor alterations. Moreover, the genetic deletion of midkine decreased the expression of the enzyme tyrosine hydroxylase in the substantia nigra reducing partially the levels of dopamine and its metabolites in the olfactory bulb and striatum of mice. These findings indicate that the genetic deletion of midkine causes a partial loss of dopaminergic neurons and depletion of dopamine, resulting in olfactory and memory deficits with no major motor impairments. Therefore, Mdk(-/-) mice may represent a promising animal model for the study of the early stages of PD and for testing new therapeutic strategies to restore sensorial and cognitive processes in PD.

Olfactory memory and maternal behaviour-induced changes in c-fos and zif/268 mRNA expression in the sheep brain.

PubMed

Da Costa, A P; Broad, K D; Kendrick, K M

1997-06-01

In sheep maternal behaviour and the formation of the selective olfactory, ewe/lamb bond are induced by feedback to the brain from stimulation of the vagina and cervix during parturition. In the present study, we have used in situ hybridization histochemistry to quantify changes in cellular expression of two immediately-early genes, c-fos and zif/268, in order to identify activated brain regions during the induction of maternal behaviour and olfactory bonding as well as regions where plastic changes are occurring during with the formation of the olfactory memory associated with bonding. Three different treatment groups were used. One group gave birth normally, became maternal and were allowed to interact with their lambs for 30 min. A second group received exogenous treatment with oestradiol and progesterone to induce lactation and then received a 5-min period of artificial stimulation of the vagina and cervix (VCS) which reliably induces maternal behaviour but could not interact with lambs. A final control group received exogenous hormone treatment but no VCS or interaction with lambs. Compared to the control group, post-partum animals and animals that had received VCS showed increased c-fos expression in a number of cortical regions (cingulate, entorhinal and somatosensory), the mediodorsal thalamic nucleus and the lateral habenula, the limbic system (bed nucleus of the stria terminalis, lateral septum, medial arnygdala, dentate gyrus and the CA3 region of the hippocampus) and the hypothalamus (medial preoptic area, mediobasal hypothalamus, paraventricular nucleus, supraoptic nucleus and periventricular complex). The group that gave birth and had contact with their lambs for 30 min had significantly enhanced c-fos mRNA expression in the cingulate cortex compared to those receiving VCS and additionally showed significantly increased c-fos mRNA expression in olfactory processing regions (olfactory bulb, piriform cortex and orbitofrontal cortex). Expression of zif/268 was significantly increased in the entorhinal cortex, orbitofrontal cortex and dentate gyrus of the parturition group compared to either the control or the VCS alone groups. These results show a clear differentiation between neural substrates controlling the expression of maternal behaviour and those involved in the olfactory memory process associated with selective recognition of offspring although at the level of the hippocampus and cingulate cortex there may be some degree of overlap. Alterations in zif/268 at tertiary processing sites for olfactory information (orbitofrontal cortex) and the entorhinal cortex and dentate gyrus may reflect plastic changes occurring during the early stages of olfactory memory formation.

Monoterpenoid-based preparations in beehives affect learning, memory, and gene expression in the bee brain.

PubMed

Bonnafé, Elsa; Alayrangues, Julie; Hotier, Lucie; Massou, Isabelle; Renom, Allan; Souesme, Guillaume; Marty, Pierre; Allaoua, Marion; Treilhou, Michel; Armengaud, Catherine

2017-02-01

Bees are exposed in their environment to contaminants that can weaken the colony and contribute to bee declines. Monoterpenoid-based preparations can be introduced into hives to control the parasitic mite Varroa destructor. The long-term effects of monoterpenoids are poorly investigated. Olfactory conditioning of the proboscis extension reflex (PER) has been used to evaluate the impact of stressors on cognitive functions of the honeybee such as learning and memory. The authors tested the PER to odorants on bees after exposure to monoterpenoids in hives. Octopamine receptors, transient receptor potential-like (TRPL), and γ-aminobutyric acid channels are thought to play a critical role in the memory of food experience. Gene expression levels of Amoa1, Rdl, and trpl were evaluated in parallel in the bee brain because these genes code for the cellular targets of monoterpenoids and some pesticides and neural circuits of memory require their expression. The miticide impaired the PER to odors in the 3 wk following treatment. Short-term and long-term olfactory memories were improved months after introduction of the monoterpenoids into the beehives. Chronic exposure to the miticide had significant effects on Amoa1, Rdl, and trpl gene expressions and modified seasonal changes in the expression of these genes in the brain. The decrease of expression of these genes in winter could partly explain the improvement of memory. The present study has led to new insights into alternative treatments, especially on their effects on memory and expression of selected genes involved in this cognitive function. Environ Toxicol Chem 2017;36:337-345. © 2016 SETAC. © 2016 SETAC.

Early survival factor deprivation in the olfactory epithelium enhances activity-driven survival

PubMed Central

François, Adrien; Laziz, Iman; Rimbaud, Stéphanie; Grebert, Denise; Durieux, Didier; Pajot-Augy, Edith; Meunier, Nicolas

2013-01-01

The neuronal olfactory epithelium undergoes permanent renewal because of environmental aggression. This renewal is partly regulated by factors modulating the level of neuronal apoptosis. Among them, we had previously characterized endothelin as neuroprotective. In this study, we explored the effect of cell survival factor deprivation in the olfactory epithelium by intranasal delivery of endothelin receptors antagonists to rat pups. This treatment induced an overall increase of apoptosis in the olfactory epithelium. The responses to odorants recorded by electroolfactogram were decreased in treated animal, a result consistent with a loss of olfactory sensory neurons (OSNs). However, the treated animal performed better in an olfactory orientation test based on maternal odor compared to non-treated littermates. This improved performance could be due to activity-dependent neuronal survival of OSNs in the context of increased apoptosis level. In order to demonstrate it, we odorized pups with octanal, a known ligand for the rI7 olfactory receptor (Olr226). We quantified the number of OSN expressing rI7 by RT-qPCR and whole mount in situ hybridization. While this number was reduced by the survival factor removal treatment, this reduction was abolished by the presence of its ligand. This improved survival was optimal for low concentration of odorant and was specific for rI7-expressing OSNs. Meanwhile, the number of rI7-expressing OSNs was not affected by the odorization in non-treated littermates; showing that the activity-dependant survival of OSNs did not affect the OSN population during the 10 days of odorization in control conditions. Overall, our study shows that when apoptosis is promoted in the olfactory mucosa, the activity-dependent neuronal plasticity allows faster tuning of the olfactory sensory neuron population toward detection of environmental odorants. PMID:24399931

Microvasculature of the Olfactory Organ in the Japanese Monkey (Macaca fuscata fuscata)

NASA Astrophysics Data System (ADS)

Okada, Shigenori; Schraufnagel, Dean E.

2002-06-01

Olfaction is an important and primitive sense. As its importance has changed with evolution, anatomic adjustments have occurred in its structure and vasculature. Primates are a family of vertebrates that have had to develop their visual system to adapt to the arboreal environment and have evolved from a macrosmatic to a microsmatic species as the optic system has enlarged. This has resulted in anatomic changes of a small but critical area at the base of the brain. This paper describes the three-dimensional vascular anatomy of the olfactory organ of the Japanese monkey (Macaca fuscata fuscata). This is best understood by dividing the organ into three parts: the olfactory tract, olfactory bulb, and olfactory nerves in the nasal mucosa. The bulb can be partitioned into an outer or cortical part and inner or medullary part. The vasculature and tissue were examined grossly and with light microscopy and scanning electron microscopy of vascular corrosion casts. The olfactory tract and bulb were supplied by an arteriole from the anterior cerebral artery on each side. The tract was supplied by capillaries running spirally with a coarse network. At the olfactory bulb, the arteriole ramified into the intracortical and medullary branches that formed capillary networks. The bulbar intracortical capillaries were divided into two layers with different densities and vascular patterns. The capillaries of the superficial layer had a ladder-like pattern. The branches that ran into the medulla of the olfactory bulb were more widely spaced. Twigs from the posterior ethmoidal artery ran along the nerve fiber and formed intra- and extrafascicular networks. Each region of the olfactory organ had characteristic three-dimensional vascular patterns that were related to their cellular architecture.

Brain architecture in the terrestrial hermit crab Coenobita clypeatus (Anomura, Coenobitidae), a crustacean with a good aerial sense of smell

PubMed Central

Harzsch, Steffen; Hansson, Bill S

2008-01-01

Background During the evolutionary radiation of Crustacea, several lineages in this taxon convergently succeeded in meeting the physiological challenges connected to establishing a fully terrestrial life style. These physiological adaptations include the need for sensory organs of terrestrial species to function in air rather than in water. Previous behavioral and neuroethological studies have provided solid evidence that the land hermit crabs (Coenobitidae, Anomura) are a group of crustaceans that have evolved a good sense of aerial olfaction during the conquest of land. We wanted to study the central olfactory processing areas in the brains of these organisms and to that end analyzed the brain of Coenobita clypeatus (Herbst, 1791; Anomura, Coenobitidae), a fully terrestrial tropical hermit crab, by immunohistochemistry against synaptic proteins, serotonin, FMRFamide-related peptides, and glutamine synthetase. Results The primary olfactory centers in this species dominate the brain and are composed of many elongate olfactory glomeruli. The secondary olfactory centers that receive an input from olfactory projection neurons are almost equally large as the olfactory lobes and are organized into parallel neuropil lamellae. The architecture of the optic neuropils and those areas associated with antenna two suggest that C. clypeatus has visual and mechanosensory skills that are comparable to those of marine Crustacea. Conclusion In parallel to previous behavioral findings of a good sense of aerial olfaction in C. clypeatus, our results indicate that in fact their central olfactory pathway is most prominent, indicating that olfaction is a major sensory modality that these brains process. Interestingly, the secondary olfactory neuropils of insects, the mushroom bodies, also display a layered structure (vertical and medial lobes), superficially similar to the lamellae in the secondary olfactory centers of C. clypeatus. More detailed analyses with additional markers will be necessary to explore the question if these similarities have evolved convergently with the establishment of superb aerial olfactory abilities or if this design goes back to a shared principle in the common ancestor of Crustacea and Hexapoda. PMID:18590553

Artificial Olfactory System for Trace Identification of Explosive Vapors Realized by Optoelectronic Schottky Sensing.

PubMed

Guo, Linjuan; Yang, Zheng; Dou, Xincun

2017-02-01

A rapid, ultrasensitive artificial olfactory system based on an individual optoelectronic Schottky junction is demonstrated for the discriminative detection of explosive vapors, including military explosives and improvised explosives. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Association between olfactory identification and parkinsonism in patients with non-affective psychosis.

PubMed

Meijer, Julia H; van Harten, Peter; Meijer, Carin J; Koeter, Maarten W; Bruggeman, Richard; Cahn, Wiepke; Kahn, René S; de Haan, L

2016-10-01

Olfactory identification deficits (OIDs) are seen in schizophrenia patients and individuals at increased risk for psychosis but its pathophysiology remains unclear. Although dopaminergic imbalance is known to lie at the core of schizophrenia symptomatology, its role in the development of OIDs has not been elucidated yet. This study investigated the association between OIDs and symptoms of parkinsonism as a derivative of dopaminergic functioning. In 320 patients diagnosed with non-affective psychosis, olfactory identification performance was assessed by means of the Sniffin' Sticks task. Level of parkinsonian symptoms was assessed by means of the Unified Parkinson's Disease Rating Scale (UPDRS-III). By means of multiple linear regression with bootstrapping, the association between UPDRS and Sniffin' Sticks score was investigated while correcting for potential confounders. A Bonferroni corrected P-value of 0.007 was used. Higher UPDRS scores significantly predicted worse olfactory identification in patients with non-affective psychosis with an unadjusted b = -0.07 (95% CI -0.10 to -0.04) and an adjusted b = -0.04 (95% CI -0.07 to -0.01). Results provide preliminary evidence that the same vulnerability may underlie the development of parkinsonism and OIDs in patients with non-affective psychosis. Further investigation should evaluate the clinical value of OIDs as a marker of dopaminergic vulnerability that may predict psychosis. © 2014 Wiley Publishing Asia Pty Ltd.

Sensory Impairments and Cognitive Function in Middle-Aged Adults.

PubMed

Schubert, Carla R; Cruickshanks, Karen J; Fischer, Mary E; Chen, Yanjun; Klein, Barbara E K; Klein, Ronald; Pinto, A Alex

2017-08-01

Hearing, visual, and olfactory impairments have been associated with cognitive impairment in older adults but less is known about associations with cognitive function in middle-aged adults. Sensory and cognitive functions were measured on participants in the baseline examination (2005-2008) of the Beaver Dam Offspring Study. Cognitive function was measured with the Trail Making tests A (TMTA) and B (TMTB) and the Grooved Peg Board test. Pure-tone audiometry, Pelli-Robson letter charts, and the San Diego Odor Identification test were used to measure hearing, contrast sensitivity, and olfaction, respectively. There were 2,836 participants aged 21-84 years with measures of hearing, visual, olfactory, and cognitive function at the baseline examination. Nineteen percent of the cohort had one sensory impairment and 3% had multiple sensory impairments. In multivariable adjusted linear regression models that included all three sensory impairments, hearing impairment, visual impairment, and olfactory impairment were each independently associated with poorer performance on the TMTA, TMTB, and Grooved Peg Board (p < .05 for all sensory impairments in all models). Participants with a sensory impairment took on average from 2 to 10 seconds longer than participants without the corresponding sensory impairment to complete these tests. Results were similar in models that included adjustment for hearing aid use. Hearing, visual and olfactory impairment were associated with poorer performance on cognitive function tests independent of the other sensory impairments and factors associated with cognition. Sensory impairments in midlife are associated with subtle deficits in cognitive function which may be indicative of early brain aging. © The Author 2017. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Latent Inhibition in an Insect: The Role of Aminergic Signaling

ERIC Educational Resources Information Center

Fernandez, Vanesa M.; Giurfa, Martin; Devaud, Jean-Marc; Farina, Walter M.

2012-01-01

Latent inhibition (LI) is a decrement in learning performance that results from the nonreinforced pre-exposure of the to-be-conditioned stimulus, in both vertebrates and invertebrates. In vertebrates, LI development involves dopamine and serotonin; in invertebrates there is yet no information. We studied differential olfactory conditioning of the…

Awake, long-term intranasal insulin treatment does not affect object memory, odor discrimination, or reversal learning in mice

PubMed Central

Bell, Genevieve A.; Fadool, Debra Ann

2017-01-01

Intranasal insulin delivery is currently being used in clinical trials to test for improvement in human memory and cognition, and in particular, for lessening memory loss attributed to neurodegenerative diseases. Studies have reported the effects of short-term intranasal insulin treatment on various behaviors, but less have examined long-term effects. The olfactory bulb contains the highest density of insulin receptors in conjunction with the highest level of insulin transport within the brain. Previous research from our laboratory has demonstrated that acute insulin intranasal delivery (IND) enhanced both short- and long-term memory as well as increased two-odor discrimination in a two-choice paradigm. Herein, we investigated the behavioral and physiological effects of chronic insulin IND. Adult, male C57BL6/J mice were intranasally treated with 5 μg/μl of insulin twice daily for 30 and 60 days. Metabolic assessment indicated no change in body weight, caloric intake, or energy expenditure following chronic insulin IND, but an increase in the frequency of meal bouts selectively in the dark cycle. Unlike acute insulin IND, which has been shown to cause enhanced performance in odor habituation/dishabituation and two-odor discrimination tasks in mice, chronic insulin IND did not enhance olfactometry-based odorant discrimination or olfactory reversal learning. In an object memory recognition task, insulin IND-treated mice performed no different from controls regardless of task duration. Biochemical analyses of the olfactory bulb revealed a modest 1.3X increase in IR kinase phosphorylation but no significant increase in Kv1.3 phosphorylation. Substrate phosphorylation of IR Kinase downstream effectors (MAPK/ERK and Akt signaling) proved to be highly variable. These data indicate that chronic administration of insulin IND in mice fails to enhance olfactory ability, object memory recognition, or a majority of systems physiology metabolic factors – as reported to elicit a modulatory effect with acute administration. This leads to two alternative interpretations regarding long-term insulin IND in mice: 1) It causes an initial stage of insulin resistance to dampen the behaviors that would normally be modulated under acute insulin IND, but ability to clear a glucose challenge is still retained, or 2) There is a lack of behavioral modulation at high concentration of insulin attributed to the twice daily intervals of hyperinsulinemia caused by insulin IND administration without any insulin resistance, per se. PMID:28259806

Awake, long-term intranasal insulin treatment does not affect object memory, odor discrimination, or reversal learning in mice.

PubMed

Bell, Genevieve A; Fadool, Debra Ann

2017-05-15

Intranasal insulin delivery is currently being used in clinical trials to test for improvement in human memory and cognition, and in particular, for lessening memory loss attributed to neurodegenerative diseases. Studies have reported the effects of short-term intranasal insulin treatment on various behaviors, but less have examined long-term effects. The olfactory bulb contains the highest density of insulin receptors in conjunction with the highest level of insulin transport within the brain. Previous research from our laboratory has demonstrated that acute insulin intranasal delivery (IND) enhanced both short- and long-term memory as well as increased two-odor discrimination in a two-choice paradigm. Herein, we investigated the behavioral and physiological effects of chronic insulin IND. Adult, male C57BL6/J mice were intranasally treated with 5μg/μl of insulin twice daily for 30 and 60days. Metabolic assessment indicated no change in body weight, caloric intake, or energy expenditure following chronic insulin IND, but an increase in the frequency of meal bouts selectively in the dark cycle. Unlike acute insulin IND, which has been shown to cause enhanced performance in odor habituation/dishabituation and two-odor discrimination tasks in mice, chronic insulin IND did not enhance olfactometry-based odorant discrimination or olfactory reversal learning. In an object memory recognition task, insulin IND-treated mice did not perform differently than controls, regardless of task duration. Biochemical analyses of the olfactory bulb revealed a modest 1.3 fold increase in IR kinase phosphorylation but no significant increase in Kv1.3 phosphorylation. Substrate phosphorylation of IR kinase downstream effectors (MAPK/ERK and Akt signaling) proved to be highly variable. These data indicate that chronic administration of insulin IND in mice fails to enhance olfactory ability, object memory recognition, or a majority of systems physiology metabolic factors - as reported to elicit a modulatory effect with acute administration. This leads to two alternative interpretations regarding long-term insulin IND in mice: 1) It causes an initial stage of insulin resistance to dampen the behaviors that would normally be modulated under acute insulin IND, but ability to clear a glucose challenge is still retained, or 2) There is a lack of behavioral modulation at high concentration of insulin attributed to the twice daily intervals of hyperinsulinemia caused by insulin IND administration without any insulin resistance, per se. Copyright © 2017 Elsevier Inc. All rights reserved.

High-throughput olfactory conditioning and memory retention test show variation in Nasonia parasitic wasps

PubMed Central

Hoedjes, K M; Steidle, J L M; Werren, J H; Vet, L E M; Smid, H M

2012-01-01

Most of our knowledge on learning and memory formation results from extensive studies on a small number of animal species. Although features and cellular pathways of learning and memory are highly similar in this diverse group of species, there are also subtle differences. Closely related species of parasitic wasps display substantial variation in memory dynamics and can be instrumental to understanding both the adaptive benefit of and mechanisms underlying this variation. Parasitic wasps of the genus Nasonia offer excellent opportunities for multidisciplinary research on this topic. Genetic and genomic resources available for Nasonia are unrivaled among parasitic wasps, providing tools for genetic dissection of mechanisms that cause differences in learning. This study presents a robust, high-throughput method for olfactory conditioning of Nasonia using a host encounter as reward. A T-maze olfactometer facilitates high-throughput memory retention testing and employs standardized odors of equal detectability, as quantified by electroantennogram recordings. Using this setup, differences in memory retention between Nasonia species were shown. In both Nasonia vitripennis and Nasonia longicornis, memory was observed up to at least 5 days after a single conditioning trial, whereas Nasonia giraulti lost its memory after 2 days. This difference in learning may be an adaptation to species-specific differences in ecological factors, for example, host preference. The high-throughput methods for conditioning and memory retention testing are essential tools to study both ultimate and proximate factors that cause variation in learning and memory formation in Nasonia and other parasitic wasp species. PMID:22804968

Activity-Dependent Dysfunction in Visual and Olfactory Sensory Systems in Mouse Models of Down Syndrome

PubMed Central

Saqran, Lubna; Herrick, Scott P.; Frosch, Matthew P.; Hyman, Bradley T.

2017-01-01

Activity-dependent synaptic plasticity plays a critical role in the refinement of circuitry during postnatal development and may be disrupted in conditions that cause intellectual disability, such as Down syndrome (DS). To test this hypothesis, visual cortical plasticity was assessed in Ts65Dn mice that harbor a chromosomal duplication syntenic to human chromosome 21q. We find that Ts65Dn mice demonstrate a defect in ocular dominance plasticity (ODP) following monocular deprivation. This phenotype is similar to that of transgenic mice that express amyloid precursor protein (APP), which is duplicated in DS and in Ts65DN mice; however, normalizing APP gene copy number in Ts65Dn mice fails to rescue plasticity. Ts1Rhr mice harbor a duplication of the telomeric third of the Ts65Dn-duplicated sequence and demonstrate the same ODP defect, suggesting a gene or genes sufficient to drive the phenotype are located in that smaller duplication. In addition, we find that Ts65Dn mice demonstrate an abnormality in olfactory system connectivity, a defect in the refinement of connections to second-order neurons in the olfactory bulb. Ts1Rhr mice do not demonstrate a defect in glomerular refinement, suggesting that distinct genes or sets of genes underlie visual and olfactory system phenotypes. Importantly, these data suggest that developmental plasticity and connectivity are impaired in sensory systems in DS model mice, that such defects may contribute to functional impairment in DS, and that these phenotypes, present in male and female mice, provide novel means for examining the genetic and molecular bases for neurodevelopmental impairment in model mice in vivo. SIGNIFICANCE STATEMENT Our understanding of the basis for intellectual impairment in Down syndrome is hindered by the large number of genes duplicated in Trisomy 21 and a lack of understanding of the effect of disease pathology on the function of neural circuits in vivo. This work describes early postnatal developmental abnormalities in visual and olfactory sensory systems in Down syndrome model mice, which provide insight into defects in the function of neural circuits in vivo and provide an approach for exploring the genetic and molecular basis for impairment in the disease. In addition, these findings raise the possibility that basic dysfunction in primary sensory circuitry may illustrate mechanisms important for global learning and cognitive impairment in Down syndrome patients. PMID:28899917

DNA methylation mediates neural processing after odor learning in the honeybee

PubMed Central

Biergans, Stephanie D.; Claudianos, Charles; Reinhard, Judith; Galizia, C. Giovanni

2017-01-01

DNA methyltransferases (Dnmts) - epigenetic writers catalyzing the transfer of methyl-groups to cytosine (DNA methylation) – regulate different aspects of memory formation in many animal species. In honeybees, Dnmt activity is required to adjust the specificity of olfactory reward memories and bees’ relearning capability. The physiological relevance of Dnmt-mediated DNA methylation in neural networks, however, remains unknown. Here, we investigated how Dnmt activity impacts neuroplasticity in the bees’ primary olfactory center, the antennal lobe (AL) an equivalent of the vertebrate olfactory bulb. The AL is crucial for odor discrimination, an indispensable process in forming specific odor memories. Using pharmacological inhibition, we demonstrate that Dnmt activity influences neural network properties during memory formation in vivo. We show that Dnmt activity promotes fast odor pattern separation in trained bees. Furthermore, Dnmt activity during memory formation increases both the number of responding glomeruli and the response magnitude to a novel odor. These data suggest that Dnmt activity is necessary for a form of homoeostatic network control which might involve inhibitory interneurons in the AL network. PMID:28240742

Odor discrimination in Drosophila: from neural population codes to behavior.

PubMed

Parnas, Moshe; Lin, Andrew C; Huetteroth, Wolf; Miesenböck, Gero

2013-09-04

Taking advantage of the well-characterized olfactory system of Drosophila, we derive a simple quantitative relationship between patterns of odorant receptor activation, the resulting internal representations of odors, and odor discrimination. Second-order excitatory and inhibitory projection neurons (ePNs and iPNs) convey olfactory information to the lateral horn, a brain region implicated in innate odor-driven behaviors. We show that the distance between ePN activity patterns is the main determinant of a fly's spontaneous discrimination behavior. Manipulations that silence subsets of ePNs have graded behavioral consequences, and effect sizes are predicted by changes in ePN distances. ePN distances predict only innate, not learned, behavior because the latter engages the mushroom body, which enables differentiated responses to even very similar odors. Inhibition from iPNs, which scales with olfactory stimulus strength, enhances innate discrimination of closely related odors, by imposing a high-pass filter on transmitter release from ePN terminals that increases the distance between odor representations. Copyright © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Dissipative vibrational model for chiral recognition in olfaction

NASA Astrophysics Data System (ADS)

Tirandaz, Arash; Taher Ghahramani, Farhad; Shafiee, Afshin

2015-09-01

We examine the olfactory discrimination of left- and right-handed enantiomers of chiral odorants based on the odorant-mediated electron transport from a donor to an acceptor of the olfactory receptors embodied in a biological environment. The chiral odorant is effectively described by an asymmetric double-well potential whose minima are associated to the left- and right-handed enantiomers. The introduced asymmetry is considered an overall measure of chiral interactions. The biological environment is conveniently modeled as a bath of harmonic oscillators. The resulting spin-boson model is adapted by a polaron transformation to derive the corresponding Born-Markov master equation with which we obtain the elastic and inelastic electron tunneling rates. We show that the inelastic tunneling through left- and right-handed enantiomers occurs with different rates. The discrimination mechanism depends on the ratio of tunneling frequency to localization frequency.

From chemical neuroanatomy to an understanding of the olfactory system

PubMed Central

Oboti, L.; Peretto, P.; De Marchis, S.; Fasolo, A.

2011-01-01

The olfactory system of mammals is the appropriate model for studying several aspects of neuronal physiology spanning from the developmental stage to neural network remodelling in the adult brain. Both the morphological and physiological understanding of this system were strongly supported by classical histochemistry. It is emblematic the case of the Olfactory Marker Protein (OMP) staining, the first, powerful marker for fully differentiated olfactory receptor neurons and a key tool to investigate the dynamic relations between peripheral sensory epithelia and central relay regions given its presence within olfactory fibers reaching the olfactory bulb (OB). Similarly, the use of thymidine analogues was able to show neurogenesis in an adult mammalian brain far before modern virus labelling and lipophilic tracers based methods. Nowadays, a wealth of new histochemical techniques combining cell and molecular biology approaches is available, giving stance to move from the analysis of the chemically identified circuitries to functional research. The study of adult neurogenesis is indeed one of the best explanatory examples of this statement. After defining the cell types involved and the basic physiology of this phenomenon in the OB plasticity, we can now analyze the role of neurogenesis in well testable behaviours related to socio-chemical communication in rodents. PMID:22297441

The Hydrodynamics and Odorant Transport Phenomena of Olfaction in the Hammerhead Shark

NASA Astrophysics Data System (ADS)

Rygg, Alex; Craven, Brent

2013-11-01

The hammerhead shark possesses a unique head morphology that is thought to facilitate enhanced olfactory performance. The olfactory organs, located at the distal ends of the cephalofoil, contain numerous lamellae that increase the surface area for olfaction. Functionally, for the shark to detect chemical stimuli, water-borne odors must reach the olfactory sensory epithelium that lines these lamellae. Thus, odorant transport from the aquatic environment to the sensory epithelium is the first critical step in olfaction. Here we investigate the hydrodynamics and odorant transport phenomena of olfaction in the hammerhead shark based on an anatomically-accurate reconstruction of the head and olfactory chamber from high-resolution micro-CT and MRI scans of a cadaver specimen. Computational fluid dynamics (CFD) simulations of water flow in the reconstructed model reveal the external and internal hydrodynamics of olfaction during swimming. Odorant transport in the olfactory organ is investigated using a multi-scale approach, whereby molecular dynamics (MD) simulations are used to calculate odorant partition coefficients that are subsequently utilized in macro-scale CFD simulations of odorant deposition. The hydrodynamic and odorant transport results are used to elucidate several important features of olfactory function in the hammerhead shark.

Intrinsic and Extrinsic Neuromodulation of Olfactory Processing.

PubMed

Lizbinski, Kristyn M; Dacks, Andrew M

2017-01-01

Neuromodulation is a ubiquitous feature of neural systems, allowing flexible, context specific control over network dynamics. Neuromodulation was first described in invertebrate motor systems and early work established a basic dichotomy for neuromodulation as having either an intrinsic origin (i.e., neurons that participate in network coding) or an extrinsic origin (i.e., neurons from independent networks). In this conceptual dichotomy, intrinsic sources of neuromodulation provide a "memory" by adjusting network dynamics based upon previous and ongoing activation of the network itself, while extrinsic neuromodulators provide the context of ongoing activity of other neural networks. Although this dichotomy has been thoroughly considered in motor systems, it has received far less attention in sensory systems. In this review, we discuss intrinsic and extrinsic modulation in the context of olfactory processing in invertebrate and vertebrate model systems. We begin by discussing presynaptic modulation of olfactory sensory neurons by local interneurons (LNs) as a mechanism for gain control based on ongoing network activation. We then discuss the cell-class specific effects of serotonergic centrifugal neurons on olfactory processing. Finally, we briefly discuss the integration of intrinsic and extrinsic neuromodulation (metamodulation) as an effective mechanism for exerting global control over olfactory network dynamics. The heterogeneous nature of neuromodulation is a recurring theme throughout this review as the effects of both intrinsic and extrinsic modulation are generally non-uniform.

Evolutionary changes of the importance of olfaction in cetaceans based on the olfactory marker protein gene.

PubMed

Kishida, Takushi; Thewissen, J G M

2012-01-25

Odontocetes and mysticetes are two extant suborders of cetaceans. It is reported that the former have no sense of olfaction, while the latter can smell in air. To explain the ecological reason why mysticetes still retain their sense of smell, two hypotheses have been proposed - the echolocation-priority hypothesis, which assumes that the acquisition of echolocation causes the reduction of the importance of olfaction, and the filter-feeder hypothesis, which assumes that olfactory ability is important for filter-feeders to locate their prey because clouds of plankton give off a peculiar odor. The olfactory marker protein (OMP) is almost exclusively expressed in vertebrate olfactory receptor neurons, and is considered to play important roles in olfactory systems. In this study, full-length open reading frames of OMP genes were identified in 6 cetacean species and we analyzed the nonsynonymous to synonymous substitution rate ratio based on the maximum likelihood method. The evolutionary changes of the selective pressures on OMP genes did fit better to the filter-feeder hypothesis than to the echolocation-priority hypothesis. In addition, no pseudogenization mutations are found in all five odontocetes OMP genes investigated in this study. It may suggest that OMP retains some function even in 'anosmic' odontocetes. Copyright © 2011 Elsevier B.V. All rights reserved.

Illuminating odors: when optogenetics brings to light unexpected olfactory abilities

PubMed Central

Grimaud, Julien

2016-01-01

For hundreds of years, the sense of smell has generated great interest in the world literature, oenologists, and perfume makers but less of scientists. Only recently this sensory modality has gained new attraction in neuroscience when original tools issued from physiology, anatomy, or molecular biology were available to decipher how the brain makes sense of olfactory cues. However, this move was promptly dampened by the difficulties of developing quantitative approaches to study the relationship between the physical characteristics of stimuli and the sensations they create. An upswing of olfactory investigations occurred when genetic tools could be used in combination with devices borrowed from the physics of light (a hybrid technique called optogenetics) to scrutinize the olfactory system and to provide greater physiological precision for studying olfactory-driven behaviors. This review aims to present the most recent studies that have used light to activate components of the olfactory pathway, such as olfactory receptor neurons, or neurons located further downstream, while leaving intact others brain circuits. With the use of optogenetics to unravel the mystery of olfaction, scientists have begun to disentangle how the brain makes sense of smells. In this review, we shall discuss how the brain recognizes odors, how it memorizes them, and how animals make decisions based on odorants they are capable of sensing. Although this review deals with olfaction, the role of light will be central throughout. PMID:27194792

Effects of nutritional status and cognitive ability on olfactory function in geriatric patients.

PubMed

Jin, Sung-Yong; Jeong, Hye Seon; Lee, Jin Woo; Kwon, Ki Ryun; Rha, Ki-Sang; Kim, Yong Min

2016-02-01

The aim of this study was to investigate the prevalence of olfactory dysfunction and evaluate the relationship between olfactory function and nutritional status, comorbidity, and the results of a neurocognitive test in geriatric patients who do not suffer from neurodegenerative disease. A total of 45 patients who visited the Geriatric Health Center of Chungnam National University Hospital were enrolled in this study. Olfactory function was assessed using a Korean Version of Sniffin' Stick Test II. Cognitive status of all participants was assessed with the MMSE-K (Korean version of the Mini-Mental State Examination). Nutritional status was assessed with body mass index, Mini-Nutritional Assessment (MNA), and serum total protein and albumin. A total of 45 participants were enrolled in this study. Of these subjects, 28 were men and 17 were women, with a mean age of 71.7±5.16 years. Nine (20%) were normosmia, 13 (28.9%) were hyposmia, and 23 (51.1%) were anosmia. Thirty-six patients (80%) suffered from olfactory dysfunction (anosmia or hyposmia). MMSE score showed significant correlation with MNA score. There were significant negative correlations between age and total TDI (threshold, discrimination, and identification) score, discrimination score, identification score, and MMSE score. MMSE score showed significant correlation with discrimination score and identification score. However, MNA score did not show any significant correlation with olfactory function test results. Although olfactory function was not influenced by nutritional status, abilities of discrimination and identification of odors were associated with cognitive function in geriatric patients. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Nose-to-Brain Delivery: Investigation of the Transport of Nanoparticles with Different Surface Characteristics and Sizes in Excised Porcine Olfactory Epithelium.

PubMed

Mistry, Alpesh; Stolnik, Snjezana; Illum, Lisbeth

2015-08-03

The ability to deliver therapeutically relevant amounts of drugs directly from the nasal cavity to the central nervous system to treat neurological diseases is dependent on the availability of efficient drug delivery systems. Increased delivery and/or therapeutic effect has been shown for drugs encapsulated in nanoparticles; however, the factors governing the transport of the drugs and/or the nanoparticles from the nasal cavity to the brain are not clear. The present study evaluates the potential transport of nanoparticles across the olfactory epithelium in relation to nanoparticle characteristics. Model systems, 20, 100, and 200 nm fluorescent carboxylated polystyrene (PS) nanoparticles that were nonmodified or surface modified with polysorbate 80 (P80-PS) or chitosan (C-PS), were assessed for transport across excised porcine olfactory epithelium mounted in a vertical Franz diffusion cell. Assessment of the nanoparticle content in the donor chamber of the diffusion cell, accompanied by fluorescence microscopy of dismounted tissues, revealed a loss of nanoparticle content from the donor suspension and their association with the excised tissue, depending on the surface properties and particle size. Chitosan surface modification of PS nanoparticles resulted in the highest tissue association among the tested systems, with the associated nanoparticles primarily located in the mucus, whereas the polysorbate 80-modified nanoparticles showed some penetration into the epithelial cell layer. Assessment of the bioelectrical properties, metabolic activity, and histology of the excised olfactory epithelium showed that C-PS nanoparticles applied in pH 6.0 buffer produced a damaging effect on the epithelial cell layer in a size-dependent manner, with fine 20 nm sized nanoparticles causing substantial tissue damage relative to that with the 100 and 200 nm counterparts. Although histology showed that the olfactory tissue was affected by the application of citrate buffer that was augmented by addition of chitosan in solution, this was not reflected in the bioelectrical parameters and the metabolic activity of the tissue. Regarding transport across the excised olfactory tissue, none of the nanoparticle systems tested, irrespective of particle size or surface modification, was transported across the epithelium to appear in measurable amounts in the receiver chamber.

The Multibasic Cleavage Site in H5N1 Virus Is Critical for Systemic Spread along the Olfactory and Hematogenous Routes in Ferrets

PubMed Central

Schrauwen, Eefje J. A.; Herfst, Sander; Leijten, Lonneke M.; van Run, Peter; Bestebroer, Theo M.; Linster, Martin; Bodewes, Rogier; Kreijtz, Joost H. C. M.; Rimmelzwaan, Guus F.; Osterhaus, Albert D. M. E.; Fouchier, Ron A. M.; Kuiken, Thijs

2012-01-01

The route by which highly pathogenic avian influenza (HPAI) H5N1 virus spreads systemically, including the central nervous system (CNS), is largely unknown in mammals. Especially, the olfactory route, which could be a route of entry into the CNS, has not been studied in detail. Although the multibasic cleavage site (MBCS) in the hemagglutinin (HA) of HPAI H5N1 viruses is a major determinant of systemic spread in poultry, the association between the MBCS and systemic spread in mammals is less clear. Here we determined the virus distribution of HPAI H5N1 virus in ferrets in time and space—including along the olfactory route—and the role of the MBCS in systemic replication. Intranasal inoculation with wild-type H5N1 virus revealed extensive replication in the olfactory mucosa, from which it spread to the olfactory bulb and the rest of the CNS, including the cerebrospinal fluid (CSF). Virus spread to the heart, liver, pancreas, and colon was also detected, indicating hematogenous spread. Ferrets inoculated intranasally with H5N1 virus lacking an MBCS demonstrated respiratory tract infection only. In conclusion, HPAI H5N1 virus can spread systemically via two different routes, olfactory and hematogenous, in ferrets. This systemic spread was dependent on the presence of the MBCS in HA. PMID:22278228

Improving intranasal delivery of neurological nanomedicine to the olfactory region using magnetophoretic guidance of microsphere carriers

PubMed Central

Xi, Jinxiang; Zhang, Ze; Si, Xiuhua A

2015-01-01

Background Although direct nose-to-brain drug delivery has multiple advantages, its application is limited by the extremely low delivery efficiency (<1%) to the olfactory region where drugs can enter the brain. It is crucial to developing new methods that can deliver drug particles more effectively to the olfactory region. Materials and methods We introduced a delivery method that used magnetophoresis to improve olfactory delivery efficiency. The performance of the proposed method was assessed numerically in an image-based human nose model. Influences of the magnet layout, magnet strength, drug-release position, and particle diameter on the olfactory dosage were examined. Results and discussion Results showed that particle diameter was a critical factor in controlling the motion of nasally inhaled ferromagnetic drug particles. The optimal particle size was found to be approximately 15 μm for effective magnetophoretic guidance while avoiding loss of particles to the walls in the anterior nose. Olfactory delivery efficiency was shown to be sensitive to the position and strength of magnets and the release position of drug particles. The results of this study showed that clinically significant olfactory doses (up to 45%) were feasible using the optimal combination of magnet layout, selective drug release, and microsphere-carrier diameter. A 64-fold-higher delivery of dosage was predicted in the magnetized nose compared to the control case, which did not have a magnetic field. However, the sensitivity of olfactory dosage to operating conditions and the unstable nature of magnetophoresis make controlled guidance of nasally inhaled aerosols still highly challenging. PMID:25709443