Lorenzo-López, Laura; Maseda, Ana; Buján, Ana; de Labra, Carmen; Amenedo, Elena; Millán-Calenti, José C
Previous studies have suggested that older adults with age-associated memory impairment (AAMI) may show a significant decline in attentional resource capacity and inhibitory processes in addition to memory impairment. In the present paper, the potential attentional capture by task-irrelevant stimuli was examined in older adults with AAMI compared to healthy older adults using scalp-recorded event-related brain potentials (ERPs). ERPs were recorded during the execution of a visual search task, in which the participants had to detect the presence of a target stimulus that differed from distractors by orientation. To explore the automatic attentional capture phenomenon, an irrelevant distractor stimulus defined by a different feature (color) was also presented without previous knowledge of the participants. A consistent N2pc, an electrophysiological indicator of attentional deployment, was present for target stimuli but not for task-irrelevant color stimuli, suggesting that these irrelevant distractors did not attract attention in AAMI older adults. Furthermore, the N2pc for targets was significantly delayed in AAMI patients compared to healthy older controls. Together, these findings suggest a specific impairment of the attentional selection process of relevant target stimuli in these individuals and indicate that the mechanism of top-down suppression of entirely task-irrelevant stimuli is preserved, at least when the target and the irrelevant stimuli are perceptually very different.
Background Cognitive impairment associated with subtle changes in neuron and neuronal network function rather than widespread neuron death is a feature of the normal aging process in humans and animals. Despite its broad evolutionary conservation, the etiology of this aging process is not well understood. However, recent evidence suggests the existence of a link between oxidative stress in the form of progressive membrane lipid peroxidation, declining neuronal electrical excitability and functional decline of the normal aging brain. The current study applies a combination of behavioural and electrophysiological techniques and pharmacological interventions to explore this hypothesis in a gastropod model (Lymnaea stagnalis feeding system) that allows pinpointing the molecular and neurobiological foundations of age-associated long-term memory (LTM) failure at the level of individual identified neurons and synapses. Results Classical appetitive reward-conditioning induced robust LTM in mature animals in the first quartile of their lifespan but failed to do so in animals in the last quartile of their lifespan. LTM failure correlated with reduced electrical excitability of two identified serotonergic modulatory interneurons (CGCs) critical in chemosensory integration by the neural network controlling feeding behaviour. Moreover, while behavioural conditioning induced delayed-onset persistent depolarization of the CGCs known to underlie appetitive LTM formation in this model in the younger animals, it failed to do so in LTM-deficient senescent animals. Dietary supplementation of the lipophilic anti-oxidant α-tocopherol reversed the effect of age on CGCs electrophysiological characteristics but failed to restore appetitive LTM function. Treatment with the SSRI fluoxetine reversed both the neurophysiological and behavioural effects of age in senior animals. Conclusions The results identify the CGCs as cellular loci of age-associated appetitive learning and memory
May, Brian H; Yang, Angela W H; Zhang, Anthony L; Owens, Michael D; Bennett, Louise; Head, Richard; Cobiac, Lynne; Li, Chun Guang; Hugel, Helmut; Story, David F; Xue, Charlie C L
This review assesses the effectiveness and safety of Chinese herbal medicines (CHM) for Mild Cognitive Impairment (MCI) and Age Associated Memory Impairment (AAMI). Electronic searches of English and Chinese databases and hand searches of Chinese journal holdings were conducted. Randomised controlled trials comparing orally administered CHM with placebo, no intervention or other therapy were considered. Ginkgo biloba was excluded. Ten trials met inclusion criteria. Eight different CHM were investigated. Methodological quality was assessed using the Jadad scale and five studies scored three or above. Two studies compared CHM with placebo and eight with another intervention. This review found an overall benefit on some outcome measures for the eight CHMs involved in the 10 RCTs but methodological and data reporting issues were evident. Meta-analysis of three studies found the effects of the CHMs were at least equivalent to piracetam on Mini-Mental State Examination (MMSE) scores. No severe adverse events were reported.
Gupta, Varun K.; Pech, Ulrike; Fulterer, Andreas; Ender, Anatoli; Mauermann, Stephan F.; Andlauer, Till F. M.; Beuschel, Christine; Thriene, Kerstin; Quentin, Christine; Schwärzel, Martin; Mielke, Thorsten; Madeo, Frank; Dengjel, Joern; Fiala, André; Sigrist, Stephan J.
Memories are assumed to be formed by sets of synapses changing their structural or functional performance. The efficacy of forming new memories declines with advancing age, but the synaptic changes underlying age-induced memory impairment remain poorly understood. Recently, we found spermidine feeding to specifically suppress age-dependent impairments in forming olfactory memories, providing a mean to search for synaptic changes involved in age-dependent memory impairment. Here, we show that a specific synaptic compartment, the presynaptic active zone (AZ), increases the size of its ultrastructural elaboration and releases significantly more synaptic vesicles with advancing age. These age-induced AZ changes, however, were fully suppressed by spermidine feeding. A genetically enforced enlargement of AZ scaffolds (four gene-copies of BRP) impaired memory formation in young animals. Thus, in the Drosophila nervous system, aging AZs seem to steer towards the upper limit of their operational range, limiting synaptic plasticity and contributing to impairment of memory formation. Spermidine feeding suppresses age-dependent memory impairment by counteracting these age-dependent changes directly at the synapse. PMID:27684064
Phospholipase A2 – nexus of aging, oxidative stress, neuronal excitability, and functional decline of the aging nervous system? Insights from a snail model system of neuronal aging and age-associated memory impairment
Hermann, Petra M.; Watson, Shawn N.; Wildering, Willem C.
The aging brain undergoes a range of changes varying from subtle structural and physiological changes causing only minor functional decline under healthy normal aging conditions, to severe cognitive or neurological impairment associated with extensive loss of neurons and circuits due to age-associated neurodegenerative disease conditions. Understanding how biological aging processes affect the brain and how they contribute to the onset and progress of age-associated neurodegenerative diseases is a core research goal in contemporary neuroscience. This review focuses on the idea that changes in intrinsic neuronal electrical excitability associated with (per)oxidation of membrane lipids and activation of phospholipase A2 (PLA2) enzymes are an important mechanism of learning and memory failure under normal aging conditions. Specifically, in the context of this special issue on the biology of cognitive aging we portray the opportunities offered by the identifiable neurons and behaviorally characterized neural circuits of the freshwater snail Lymnaea stagnalis in neuronal aging research and recapitulate recent insights indicating a key role of lipid peroxidation-induced PLA2 as instruments of aging, oxidative stress and inflammation in age-associated neuronal and memory impairment in this model system. The findings are discussed in view of accumulating evidence suggesting involvement of analogous mechanisms in the etiology of age-associated dysfunction and disease of the human and mammalian brain. PMID:25538730
Mei, Yufei; Jiang, Chun; Wan, You; Lv, Jihui; Jia, Jianping; Wang, Xiaomin; Yang, Xu; Tong, Zhiqian
A norepinephrine (NE) deficiency has been observed in aged rats and in patients with Alzheimer's disease and is thought to cause cognitive disorder. Which endogenous factor induces NE depletion, however, is largely unknown. In this study, we investigated the effects of aging-associated formaldehyde (FA) on the inactivation of NE in vitro and in vivo, and on memory behaviors in rodents. The results showed that age-related DNA demethylation led to hippocampal FA accumulation, and when this occurred, the hippocampal NE content was reduced in healthy male rats of different ages. Furthermore, biochemical analysis revealed that FA rapidly inactivated NE in vitro and that an intrahippocampal injection of FA markedly reduced hippocampal NE levels in healthy adult rats. Unexpectedly, an injection of FA (at a pathological level) or 6-hydroxydopamine (6-OHDA, a NE depletor) can mimic age-related NE deficiency, long-term potentiation (LTP) impairments, and spatial memory deficits in healthy adult rats. Conversely, an injection of NE reversed age-related deficits in both LTP and memory in aged rats. In agreement with the above results, the senescence-accelerated prone 8 (SAMP8) mice also exhibited a severe deficit in LTP and memory associated with a more severe NE deficiency and FA accumulation, when compared with the age-matched, senescence-resistant 1 (SAMR1) mice. Injection of resveratrol (a natural FA scavenger) or NE into SAMP8 mice reversed FA accumulation and NE deficiency and restored the magnitude of LTP and memory. Collectively, these findings suggest that accumulated FA is a critical endogenous factor for aging-associated NE depletion and cognitive decline.
Aging is associated with severe thermogenic impairment, which contributes to obesity and diabetes in aging. We previously reported that ablation of the ghrelin receptor, growth hormone secretagogue receptor (GHS-R), attenuates age-associated obesity and insulin resistance. Ghrelin and obestatin are ...
Baird, Gillian; Dworzynski, Katharina; Slonims, Vicky; Simonoff, Emily
Aim: The aim of this study was to assess whether any memory impairment co-occurring with language impairment is global, affecting both verbal and visual domains, or domain specific. Method: Visual and verbal memory, learning, and processing speed were assessed in children aged 6 years to 16 years 11 months (mean 9y 9m, SD 2y 6mo) with current,…
Kunieda, Takeshige; Minamino, Tohru; Miura, Kentaro; Katsuno, Taro; Tateno, Kaoru; Miyauchi, Hideyuki; Kaneko, Shuichi; Bradfield, Christopher A; FitzGerald, Garret A; Komuro, Issei
Impairment of circadian rhythmicity in the elderly has been suggested to cause age-associated diseases such as atherosclerosis and hypertension. Endothelium-derived nitric oxide (NO) is a critical regulator of cardiovascular homeostasis, but its production declines with aging, thereby inducing vascular dysfunction. We show here that impaired circadian rhythmicity is related to a decrease of NO production with aging. Treatment with an NO donor significantly upregulated the promoter activity of the clock gene Period via the cAMP response element-dependent and the E-box enhancer element-dependent pathways. Both phosphorylation and S-nitrosylation by NO are involved in this upregulation. In aged animals, endothelial NO synthase activity was markedly decreased during the daytime, along with impairment of clock gene expression and the circadian variation in blood pressure. Treatment of aged animals with an NO donor significantly improved the impairments. Inhibition of NO synthase activity also led to impairment of clock gene expression and blood pressure rhythm. These results suggest that NO is a key regulator of the circadian clock in the cardiovascular system and may be a novel target for the treatment of age-associated alteration of circadian rhythms.
Painter, Michio W.; Brosius Lutz, Amanda; Cheng, Yung-Chih; Latremoliere, Alban; Duong, Kelly; Miller, Christine M.; Posada, Sean; Cobos, Enrique J.; Zhang, Alice X.; Wagers, Amy J.; Havton, Leif A.; Barres, Ben; Omura, Takao
SUMMARY The regenerative capacity of the peripheral nervous system declines with age. Why this occurs, however, is unknown. We demonstrate that 24-month old mice exhibit an impairment of functional recovery after nerve injury compared to 2-month old animals. We find no difference in the intrinsic growth capacity between aged and young sensory neurons in vitro nor in their ability to activate growth-associated transcriptional programs after injury. Instead, using age-mismatched nerve transplants in vivo, we show that the extent of functional recovery depends on the age of the nerve graft, and not the age of the host. Molecular interrogation of the sciatic nerve reveals that aged Schwann cells (SCs) fail to rapidly activate a transcriptional repair program after injury. Functionally, aged SCs exhibit impaired de-differentiation, myelin clearance and macrophage recruitment. These results suggest that the age-associated decline in axonal regeneration results from diminished Schwann cell plasticity, leading to slower myelin clearance. PMID:25033179
Loh, Dawn H; Jami, Shekib A; Flores, Richard E; Truong, Danny; Ghiani, Cristina A; O’Dell, Thomas J; Colwell, Christopher S
Robust sleep/wake rhythms are important for health and cognitive function. Unfortunately, many people are living in an environment where their circadian system is challenged by inappropriate meal- or work-times. Here we scheduled food access to the sleep time and examined the impact on learning and memory in mice. Under these conditions, we demonstrate that the molecular clock in the master pacemaker, the suprachiasmatic nucleus (SCN), is unaltered while the molecular clock in the hippocampus is synchronized by the timing of food availability. This chronic circadian misalignment causes reduced hippocampal long term potentiation and total CREB expression. Importantly this mis-timed feeding resulted in dramatic deficits in hippocampal-dependent learning and memory. Our findings suggest that the timing of meals have far-reaching effects on hippocampal physiology and learned behaviour. DOI: http://dx.doi.org/10.7554/eLife.09460.001 PMID:26652002
Boss, B J
Two varieties of memory disorders can be distinguished--those characterized by the phenomenon of forgetfulness and those characterized by the presence of an amnesic state. Although these two conditions may appear similar, they have different anatomical correlates and functional significance. States of forgetfulness and amnesia arise from different etiologies, have different prognoses and require different therapeutic regimes. The purpose of this article is to distinguish these two varieties of memory disorders and contrast them as to anatomical features, functional differences, etiologies, prognoses and therapeutic management regimes. This should assist the neuroscience nurse to better understand relevant nursing assessment features and plan appropriate therapeutic nursing interventions for the client. Teaching protocols for families and significant others as well as clients with memory impairments should also be enhanced.
Palchykova, S.; Tobler, I.
It is now well known that daily torpor induces a sleep deficit. Djungarian hamsters emerging from this hypometabolic state spend most of the time in sleep. This sleep is characterized by high initial values of EEG slow-wave activity (SWA) that monotonically decline during recovery sleep. These features resemble the changes seen in numerous species during recovery after prolonged wakefulness or sleep deprivation (SD). When hamsters are totally or partially sleep deprived immediately after emerging from torpor, an additional increase in SWA can be induced. It has been therefore postulated, that these slow- waves are homeostatically regulated, as predicted by the two-process model of sleep regulation, and that during daily torpor a sleep deficit is accumulated as it is during prolonged waking. The predominance of SWA in the frontal EEG observed both after SD and daily torpor provides further evidence for the similarity of these conditions. It has been shown in several animal and human studies that sleep can enhance memory consolidation, and that SD leads to memory impairment. Preliminary data obtained in the Djungarian hamster showed that both SD and daily torpor result in object recognition deficits. Thus, animals subjected to SD immediately after learning, or if they underwent an episode of daily torpor between learning and retention, displayed impaired recognition memory for complex object scenes. The investigation of daily torpor can reveal mechanisms that could have important implications for hypometabolic state induction in other mammalian species, including humans.
Stamm, Andrew W; Nguyen, Nam D; Seicol, Benjamin J; Fagan, Abigail; Oh, Angela; Drumm, Michael; Lundt, Maureen; Stickgold, Robert; Wamsley, Erin J
Post-learning sleep is beneficial for human memory. However, it may be that not all memories benefit equally from sleep. Here, we manipulated a spatial learning task using monetary reward and performance feedback, asking whether enhancing the salience of the task would augment overnight memory consolidation and alter its incorporation into dreaming. Contrary to our hypothesis, we found that the addition of reward impaired overnight consolidation of spatial memory. Our findings seemingly contradict prior reports that enhancing the reward value of learned information augments sleep-dependent memory processing. Given that the reward followed a negative reinforcement paradigm, consolidation may have been impaired via a stress-related mechanism.
Arutiunian, A V; Korenevskiĭ, A V
This review covers present-day ideas of the female organism reproductive system neuroendocrine regulation in aging. The literature data on the key role of the hypothalamus in formation, organization and age-related decline of the reproductive function in both mammals and humans are considered in detail. Special focus is on catecholamines, peptides and other biologically active compounds acting in these processes. The authors discuss data showing interaction between the suprachiasmatic nuclei of the hypothalamus and the pineal gland synchronizing circadian and diurnal rhythms of gonadotropine-releasing hormone being normally synthesised and secreted during the reproductive period, but failing in aging or under the influence of neurotoxic compounds. Molecular mechanisms of ovarian cycle hypothalamic regulation impairment and possible ways of its correction by means of melatonin and peptide preparations from the pineal gland are described. The data presented may be of utility to prevent premature aging of reproductive function.
Lee, Bora; Lee, Seung-Min; Bahn, Young Jae; Lee, Kwang-Pyo; Kang, Moonkyung; Kim, Yeon-Soo; Woo, Sun-Hee; Lim, Jae-Young; Kim, Eunhee; Kwon, Ki-Sun
Skeletal muscle mass and power decrease with age, leading to impairment of mobility and metabolism in the elderly. Ca2+ signaling is crucial for myoblast differentiation as well as muscle contraction through activation of transcription factors and Ca2+-dependent kinases and phosphatases. Ca2+ channels, such as dihydropyridine receptor (DHPR), two-pore channel (TPC) and inositol 1,4,5-triphosphate receptor (ITPR), function to maintain Ca2+ homeostasis in myoblasts. Here, we observed a significant decrease in expression of type 1 IP3 receptor (ITPR1), but not types 2 and 3, in aged mice skeletal muscle and isolated myoblasts, compared with those of young mice. ITPR1 knockdown using shRNA-expressing viruses in C2C12 myoblasts and tibialis anterior muscle of mice inhibited myotube formation and muscle regeneration after injury, respectively, a typical phenotype of aged muscle. This aging phenotype was associated with repression of muscle-specific genes and activation of the epidermal growth factor receptor (EGFR)-Ras-extracellular signal-regulated kinase (ERK) pathway. ERK inhibition by U0126 not only induced recovery of myotube formation in old myoblasts but also facilitated muscle regeneration after injury in aged muscle. The conserved decline in ITPR1 expression in aged human skeletal muscle suggests utility as a potential therapeutic target for sarcopenia, which can be treated using ERK inhibition strategies. PMID:27658230
Henry, Lucy A.; Botting, Nicola
Children with developmental language impairments (DLI) are often reported to show difficulties with working memory. This review describes the four components of the well-established working memory model, and considers whether there is convincing evidence for difficulties within each component in children with DLI. The emphasis is on the most…
Bisby, James A; Burgess, Neil
The formation of associations between items and their context has been proposed to rely on mechanisms distinct from those supporting memory for a single item. Although emotional experiences can profoundly affect memory, our understanding of how it interacts with different aspects of memory remains unclear. We performed three experiments to examine the effects of emotion on memory for items and their associations. By presenting neutral and negative items with background contexts, Experiment 1 demonstrated that item memory was facilitated by emotional affect, whereas memory for an associated context was reduced. In Experiment 2, arousal was manipulated independently of the memoranda, by a threat of shock, whereby encoding trials occurred under conditions of threat or safety. Memory for context was equally impaired by the presence of negative affect, whether induced by threat of shock or a negative item, relative to retrieval of the context of a neutral item in safety. In Experiment 3, participants were presented with neutral and negative items as paired associates, including all combinations of neutral and negative items. The results showed both above effects: compared to a neutral item, memory for the associate of a negative item (a second item here, context in Experiments 1 and 2) is impaired, whereas retrieval of the item itself is enhanced. Our findings suggest that negative affect impairs associative memory while recognition of a negative item is enhanced. They support dual-processing models in which negative affect or stress impairs hippocampal-dependent associative memory while the storage of negative sensory/perceptual representations is spared or even strengthened.
Kluen, Lisa Marieke; Agorastos, Agorastos; Wiedemann, Klaus; Schwabe, Lars
Memory generalization is essential for adaptive decision-making and action. Our ability to generalize across past experiences relies on medial-temporal lobe structures, known to be highly sensitive to stress. Recent evidence suggests that stressful events may indeed interfere with memory generalization. Yet, the mechanisms involved in this generalization impairment are unknown. We tested here whether a pharmacological elevation of major stress mediators, noradrenaline, and glucocorticoids is sufficient to disrupt memory generalization. In a double-blind, placebo-controlled design, healthy men and women received orally a placebo, hydrocortisone, the α2-adrenoceptor antagonist yohimbine that leads to increased noradrenergic stimulation, or both drugs, before they completed an associative learning task probing memory generalization. Drugs left learning performance intact. Yohimbine, however, led to a striking generalization impairment in women, but not in men. Hydrocortisone, in turn, had no effect on memory generalization, neither in men nor in women. The present findings indicate that increased noradrenergic activity, but not cortisol, is sufficient to disrupt memory generalization in a sex-specific manner, with relevant implications for stress-related mental disorders characterized by generalization deficits.
Chugh, Gaurav; Asghar, Mohammad; Patki, Gaurav; Bohat, Ritu; Jafri, Faizan; Allam, Farida; Dao, An T; Mowrey, Christopher; Alkadhi, Karim; Salim, Samina
Aging-associated declines in cognitive, emotional, and cardiovascular function are well known. Environmental stress triggers critical changes in the brain, further compromising cardiovascular and behavioral health during aging. Excessive dietary salt intake is one such stressor. Here, we tested the effect of high salt (HS) on anxiety, learning-memory function, and blood pressure (BP) in male Fischer brown Norway (FBN) rats. Adult (A; 2 mo) and old (O; 20 mo) male rats were fed normal-salt (NS; 0.4% NaCl) or HS (8% NaCl) diets for 4 wk after being implanted with telemeter probes for conscious BP measurement. Thereafter, tests to assess anxiety-like behavior and learning-memory were conducted. The rats were then killed, and samples of plasma, urine, and brain tissue were collected. We found that systolic BP was higher in O-NS (117 ± 1.2 mm Hg) than in A-NS (105 ± 0.8 mm Hg) rats (P < 0.05). Furthermore, BP was higher in O-HS (124 ± 1.4 mm Hg) than in O-NS (117 ± 1.2 mm Hg) rats (P < 0.05). Moreover, anxiety-like behavior (light-dark and open-field tests) was not different between A-NS and O-NS rats but was greater in O-HS rats than in A-NS, O-NS, or A-HS rats (P < 0.05). Short-term memory (radial arm water maze test) was similar in A-NS and O-NS rats but was significantly impaired in O-HS rats compared with A-NS, O-NS, or A-HS rats (P < 0.05). Furthermore, oxidative stress variables (in plasma, urine, and brain) as well as corticosterone (plasma) were greater in O-HS rats when compared with A-NS, O-NS, or A-HS rats (P < 0.05). The antioxidant enzyme glyoxalase-1 expression was selectively reduced in the hippocampus and amygdala of O-HS rats compared with A-NS, O-NS, or A-HS rats (P < 0.05), whereas other antioxidant enzymes, glutathione reductase 1, manganese superoxide dismutase (SOD), and Cu/Zn SOD remained unchanged. We suggest that salt-sensitive hypertension and behavioral derangement are associated with a redox imbalance in the brain of aged FBN rats.
Algarabel, Salvador; Fuentes, Manuel; Escudero, Joaquín; Pitarque, Alfonso; Peset, Vicente; Mazón, José-Francisco; Meléndez, Juan-Carlos
There is no agreement on the pattern of recognition memory deficits characteristic of patients diagnosed with mild cognitive impairment (MCI). Whereas lower performance in recollection is the hallmark of MCI, there is a strong controversy about possible deficits in familiarity estimates when using recognition memory tasks. The aim of this research is to shed light on the pattern of responding in recollection and familiarity in MCI. Five groups of participants were tested. The main participant samples were those formed by two MCI groups differing in age and an Alzheimer's disease group (AD), which were compared with two control groups. Whereas one of the control groups served to assess the performance of the MCI and AD people, the other one, composed of young healthy participants, served the purpose of evaluating the adequacy of the experimental tasks used in the evaluation of the different components of recognition memory. We used an associative recognition task as a direct index of recollection and a choice task on a pair of stimuli, one of which was perceptually similar to those studied in the associative recognition phase, as an index of familiarity. Our results indicate that recollection decreases with age and neurological status, and familiarity remains stable in the elderly control sample but it is deficient in MCI. This research shows that a unique encoding situation generated deficits in recollective and familiarity mechanisms in mild cognitive impaired individuals, providing evidence for the existence of deficits in both retrieval processes in recognition memory in a MCI stage.
Schwabe, Lars; Wolf, Oliver T
Converging lines of evidence indicate that stress either before or after learning influences memory. Surprisingly little is known about how memory is affected when people learn while they are stressed. Here, we examined the impact of learning under stress in 48 healthy young men and women. Participants were exposed to stress (socially evaluated cold pressor test) or a control condition while they learned emotional words and neutral words that were either conceptually associated with or unrelated to the stressor. Memory was assessed in free recall and recognition tests 24h after learning. Learning under stress reduced both free recall and recognition performance, irrespective of the emotionality and the stress context relatedness of the words. While the effect of stress was comparable in men and women, women outperformed men in the free recall test. These findings show a memory impairing effect of learning under stress in humans and challenge some assumptions of current theories about the impact of stress around the time of learning on memory formation.
Mather, Mara; Gorlick, Marissa; Nesmith, Kathryn
Showing an arousing central stimulus in a scene often leads to enhanced memory for the arousing central information and impaired memory for peripheral details. However, it is not clear from previous work whether arousing stimuli impair memory for all non-arousing nearby information or just background information. In several experiments, we tested how emotionally arousing pictures affect memory for nearby pictures and for background information. We found that when two pictures were presented together, having one of the pictures be arousing did not affect item and location memory for the other picture. In contrast, an arousing picture impaired memory for a background pattern. These findings suggest that arousal impairs memory for information that is the target of perceptual suppression, such as background information when there is a figure-ground distinction, but does not impair memory for other foreground information. PMID:19827704
Although Alzheimer's disease (AD) is a common cause of memory impairment and dementia in the elderly disturbed memory function is a widespread subjective and/or objective symptom in a variety of medical conditions. The early detection and correct distinction of AD from non-AD memory impairment is critically important to detect possibly treatable and reversible underlying causes. In the context of clinical research, it is crucial to correctly distinguish between AD or non-AD memory impairment in order to build homogenous study populations for the assessment of new therapeutic possibilities. The distinction of AD from non-AD memory impairment may be difficult, especially in mildly affected patients, due to an overlap of clinical symptoms and biomarker alterations between AD and certain non-AD conditions. This review aims to describe recent aspects of the differential diagnosis of AD and non-AD related memory impairment and how these may be considered in the presence of memory deficits.
Lum, Jarrad A G; Conti-Ramsden, Gina; Page, Debra; Ullman, Michael T
According to the Procedural Deficit Hypothesis (PDH), abnormalities of brain structures underlying procedural memory largely explain the language deficits in children with specific language impairment (SLI). These abnormalities are posited to result in core deficits of procedural memory, which in turn explain the grammar problems in the disorder. The abnormalities are also likely to lead to problems with other, non-procedural functions, such as working memory, that rely at least partly on the affected brain structures. In contrast, declarative memory is expected to remain largely intact, and should play an important compensatory role for grammar. These claims were tested by examining measures of working, declarative and procedural memory in 51 children with SLI and 51 matched typically-developing (TD) children (mean age 10). Working memory was assessed with the Working Memory Test Battery for Children, declarative memory with the Children's Memory Scale, and procedural memory with a visuo-spatial Serial Reaction Time task. As compared to the TD children, the children with SLI were impaired at procedural memory, even when holding working memory constant. In contrast, they were spared at declarative memory for visual information, and at declarative memory in the verbal domain after controlling for working memory and language. Visuo-spatial short-term memory was intact, whereas verbal working memory was impaired, even when language deficits were held constant. Correlation analyses showed neither visuo-spatial nor verbal working memory was associated with either lexical or grammatical abilities in either the SLI or TD children. Declarative memory correlated with lexical abilities in both groups of children. Finally, grammatical abilities were associated with procedural memory in the TD children, but with declarative memory in the children with SLI. These findings replicate and extend previous studies of working, declarative and procedural memory in SLI. Overall, we
Habbas, Samia; Santello, Mirko; Becker, Denise; Stubbe, Hiltrud; Zappia, Giovanna; Liaudet, Nicolas; Klaus, Federica R; Kollias, George; Fontana, Adriano; Pryce, Christopher R; Suter, Tobias; Volterra, Andrea
The occurrence of cognitive disturbances upon CNS inflammation or infection has been correlated with increased levels of the cytokine tumor necrosis factor-α (TNFα). To date, however, no specific mechanism via which this cytokine could alter cognitive circuits has been demonstrated. Here, we show that local increase of TNFα in the hippocampal dentate gyrus activates astrocyte TNF receptor type 1 (TNFR1), which in turn triggers an astrocyte-neuron signaling cascade that results in persistent functional modification of hippocampal excitatory synapses. Astrocytic TNFR1 signaling is necessary for the hippocampal synaptic alteration and contextual learning-memory impairment observed in experimental autoimmune encephalitis (EAE), an animal model of multiple sclerosis (MS). This process may contribute to the pathogenesis of cognitive disturbances in MS, as well as in other CNS conditions accompanied by inflammatory states or infections.
Martinos, Marina M.; Yoong, Michael; Patil, Shekhar; Chin, Richard F. M.; Neville, Brian G.; Scott, Rod C.; de Haan, Michelle
Children with a history of a prolonged febrile seizure show signs of acute hippocampal injury on magnetic resonance imaging. In addition, animal studies have shown that adult rats who suffered febrile seizures during development reveal memory impairments. Together, these lines of evidence suggest that memory impairments related to hippocampal…
Archibald, Lisa M. D.; Harder Griebeling, Katherine
Background: Working memory deficits have been found for children with specific language impairment (SLI) on tasks imposing increasing short-term memory load with or without additional, consistent (and simple) processing load. Aims: To examine the processing function of working memory in children with low language (LL) by employing tasks imposing…
Navarro, N M; Krawczyk, M C; Boccia, M M; Blake, M G
Pre-training administration of scopolamine (SCP) resembles situations of cholinergic dysfunction, leading to memory impairment of mice trained in an inhibitory avoidance task. We suggest here that SCP does not impair memory formation, but acquisition is affected in a way that reduces the strength of the stored memory, thus making this memory less able to control behavior when tested. Hence, a memory trace is stored, but is poorly expressed during the test. Although weakly expressed, this memory shows extinction during successive tests, and can be strengthened by using a reminder. Our results indicate that memories stored under cholinergic dysfunction conditions seem absent or lost, but are in fact present and experience common memory processes, such as extinction, and could be even recovered by using appropriate protocols.
UNVERZAGT, FREDERICK W.; KASTEN, LINDA; JOHNSON, KATHY E.; REBOK, GEORGE W.; MARSISKE, MICHAEL; KOEPKE, KATHY MANN; ELIAS, JEFFREY W.; MORRIS, JOHN N.; WILLIS, SHERRY L.; BALL, KARLENE; REXROTH, DANIEL F.; SMITH, DAVID M.; WOLINSKY, FREDRIC D.; TENNSTEDT, SHARON L.
Cognitive training improves mental abilities in older adults, but the trainability of persons with memory impairment is unclear. We conducted a subgroup analysis of subjects in the Advanced Cognitive Training for Independent and Vital Elderly (ACTIVE) trial to examine this issue. ACTIVE enrolled 2802 non-demented, community-dwelling adults aged 65 years and older and randomly assigned them to one of four groups: Memory training, reasoning training, speed-of-processing training, or no-contact control. For this study, participants were defined as memory-impaired if baseline Rey Auditory Verbal Learning Test (AVLT) sum recall score was 1.5 SD or more below predicted AVLT sum recall score from a regression-derived formula using age, education, ethnicity, and vocabulary from all subjects at baseline. Assessments were taken at baseline (BL), post-test, first annual (A1), and second annual (A2) follow-up. One hundred and ninety-three subjects were defined as memory-impaired and 2580 were memory-normal. Training gain as a function memory status (impaired vs. normal) was compared in a mixed effects model. Results indicated that memory-impaired participants failed to benefit from Memory training but did show normal training gains after reasoning and speed training. Memory function appears to mediate response to structured cognitive interventions in older adults. PMID:17942013
MacKenzie, Graham; Powell, Tim F; Donaldson, David I
Despite widespread belief that memory is enhanced by emotion, evidence also suggests that emotion can impair memory. Here we test predictions inspired by object-based binding theory, which states that memory enhancement or impairment depends on the nature of the information to be retrieved. We investigated emotional memory in the context of source retrieval, using images of scenes that were negative, neutral or positive in valence. At study each scene was paired with a colour and during retrieval participants reported the source colour for recognised scenes. Critically, we isolated effects of valence by equating stimulus arousal across conditions. In Experiment 1 colour borders surrounded scenes at study: memory impairment was found for both negative and positive scenes. Experiment 2 used colours superimposed over scenes at study: valence affected source retrieval, with memory impairment for negative scenes only. These findings challenge current theories of emotional memory by showing that emotion can impair memory for both intrinsic and extrinsic source information, even when arousal is equated between emotional and neutral stimuli, and by dissociating the effects of positive and negative emotion on episodic memory retrieval.
Haddock, Geoffrey; Newson, Margaret; Haworth, Judy
This research explored whether individuals diagnosed with probable Alzheimer's disease report stable attitudes. Two groups of participants (16 memory-impaired individuals with dementia and 16 matched controls without memory impairment) were presented with photos of various common objects and asked to indicate their attitude towards each object. Participants completed this task on two occasions, separated by 1 week. The results of the experiment revealed that memory-impaired individuals showed significant stability across time in their attitudes, although their level of attitude stability was less pronounced than that demonstrated by the matched controls. Theoretical and applied implications of the results are discussed.
Konkel, Alex; Warren, David E; Duff, Melissa C; Tranel, Daniel N; Cohen, Neal J
Relational memory theory holds that the hippocampus supports, and amnesia following hippocampal damage impairs, memory for all manner of relations. Unfortunately, many studies of hippocampal-dependent memory have either examined only a single type of relational memory or conflated multiple kinds of relations. The experiments reported here employed a procedure in which each of several kinds of relational memory (spatial, associative, and sequential) could be tested separately using the same materials. In Experiment 1, performance of amnesic patients with medial temporal lobe (MTL) damage was assessed on memory for the three types of relations as well as for items. Compared to the performance of matched comparison participants, amnesic patients were impaired on all three relational tasks. But for those patients whose MTL damage was limited to the hippocampus, performance was relatively preserved on item memory as compared to relational memory, although still lower than that of comparison participants. In Experiment 2, study exposure was reduced for comparison participants, matching their item memory to the amnesic patients in Experiment 1. Relational memory performance of comparison subjects was well above amnesic patient levels, showing the disproportionate dependence of all three relational memory performances on the integrity of the hippocampus. Correlational analyses of the various task performances of comparison participants and of college-age participants showed that our measures of item memory were not influenced significantly by memory for associations among the items.
Yeung, Lok-Kin; Ryan, Jennifer D; Cowell, Rosemary A; Barense, Morgan D
A fundamental assumption underlying most current theories of amnesia is that memory impairments arise because previously studied information either is lost rapidly or is made inaccessible (i.e., the old information appears to be new). Recent studies in rodents have challenged this view, suggesting instead that under conditions of high interference, recognition memory impairments following medial temporal lobe damage arise because novel information appears as though it has been previously seen. Here, we developed a new object recognition memory paradigm that distinguished whether object recognition memory impairments were driven by previously viewed objects being treated as if they were novel or by novel objects falsely recognized as though they were previously seen. In this indirect, eyetracking-based passive viewing task, older adults at risk for mild cognitive impairment showed false recognition to high-interference novel items (with a significant degree of feature overlap with previously studied items) but normal novelty responses to low-interference novel items (with a lower degree of feature overlap). The indirect nature of the task minimized the effects of response bias and other memory-based decision processes, suggesting that these factors cannot solely account for false recognition. These findings support the counterintuitive notion that recognition memory impairments in this memory-impaired population are not characterized by forgetting but rather are driven by the failure to differentiate perceptually similar objects, leading to the false recognition of novel objects as having been seen before.
Muñoz-López, Mónica; Hoskote, Aparna; Chadwick, Martin J; Dzieciol, Anna M; Gadian, David G; Chong, Kling; Banks, Tina; de Haan, Michelle; Baldeweg, Torsten; Mishkin, Mortimer; Vargha-Khadem, Faraneh
Neonatal hypoxia can lead to hippocampal atrophy, which can lead, in turn, to memory impairment. To test the generalizability of this causal sequence, we examined a cohort of 41 children aged 8-16, who, having received the arterial switch operation to correct for transposition of the great arteries, had sustained significant neonatal cyanosis but were otherwise neurodevelopmentally normal. As predicted, the cohort had significant bilateral reduction of hippocampal volumes relative to the volumes of 64 normal controls. They also had significant, yet selective, impairment of episodic memory as measured by standard tests of memory, despite relatively normal levels of intelligence, academic attainment, and verbal fluency. Across the cohort, degree of memory impairment was correlated with degree of hippocampal atrophy suggesting that even as early as neonatal life no other structure can fully compensate for hippocampal injury and its special role in serving episodic long term memory. © 2017 Wiley Periodicals, Inc.
Hoskote, Aparna; Chadwick, Martin J.; Dzieciol, Anna M.; Gadian, David G.; Chong, Kling; Banks, Tina; de Haan, Michelle; Baldeweg, Torsten; Mishkin, Mortimer; Vargha‐Khadem, Faraneh
ABSTRACT Neonatal hypoxia can lead to hippocampal atrophy, which can lead, in turn, to memory impairment. To test the generalizability of this causal sequence, we examined a cohort of 41 children aged 8‐16, who, having received the arterial switch operation to correct for transposition of the great arteries, had sustained significant neonatal cyanosis but were otherwise neurodevelopmentally normal. As predicted, the cohort had significant bilateral reduction of hippocampal volumes relative to the volumes of 64 normal controls. They also had significant, yet selective, impairment of episodic memory as measured by standard tests of memory, despite relatively normal levels of intelligence, academic attainment, and verbal fluency. Across the cohort, degree of memory impairment was correlated with degree of hippocampal atrophy suggesting that even as early as neonatal life no other structure can fully compensate for hippocampal injury and its special role in serving episodic long term memory. © 2017 Wiley Periodicals, Inc. PMID:28032672
Jones, Catherine R. G.; Happe, Francesca; Pickles, Andrew; Marsden, Anita J. S.; Tregay, Jenifer; Baird, Gillian; Simonoff, Emily; Charman, Tony
"Everyday memory" is conceptualised as memory within the context of day-to-day life and, despite its functional relevance, has been little studied in individuals with autism spectrum disorders (ASDs). In the first study of its kind, 94 adolescents with an ASD and 55 without an ASD completed measures of everyday memory from the Rivermead…
Stamm, Andrew W.; Nguyen, Nam D.; Seicol, Benjamin J.; Fagan, Abigail; Oh, Angela; Drumm, Michael; Lundt, Maureen; Stickgold, Robert; Wamsley, Erin J.
Post-learning sleep is beneficial for human memory. However, it may be that not all memories benefit equally from sleep. Here, we manipulated a spatial learning task using monetary reward and performance feedback, asking whether enhancing the salience of the task would augment overnight memory consolidation and alter its incorporation into…
Hermelin, B; Pring, L; Buhler, M; Wolff, S; Heaton, P
In this single case study, paintings by a visually impaired and cognitively handicapped savant artist are evaluated. He paints his pictures exclusively from memory, either after having looked at a natural scene through binoculars, or after studying landscape photographs in brochures, catalogues, and books. The paintings are compared with the models from which they were derived, and the resulting generative changes are accounted for by an interaction between impaired visual input and memory transformations.
Nardone, Raffaele; Höller, Yvonne; Bathke, Arne C; Höller, Peter; Lochner, Piergiorgio; Tezzon, Frediano; Trinka, Eugen; Brigo, Francesco
Subjective memory impairment (SMI) is being increasingly recognized as a preclinical phase of Alzheimer disease (AD). Short latency afferent inhibition (SAI) is helpful in demonstrating dysfunction of central cholinergic circuits, and was reported to be abnormal in patients with AD and amnestic multiple domain mild cognitive impairment. In this study, we found normal SAI in 20 subjects with SMI. SAI could be a useful biomarker for identifying, among individuals with memory complaints, those in whom cholinergic degeneration has occurred.
Ahmed, Samrah; Baker, Ian; Husain, Masud; Thompson, Sian; Kipps, Christopher; Hornberger, Michael; Hodges, John R; Butler, Christopher R
Posterior cortical atrophy (PCA) is characterized by core visuospatial and visuoperceptual deficits, and predominant atrophy in the parieto-occipital cortex. The most common underlying pathology is Alzheimer's disease (AD). Existing diagnostic criteria suggest that episodic memory is relatively preserved. The aim of this study was to examine memory performance at initial clinical presentation in PCA, compared to early-onset AD patients (EOAD). 15 PCA patients and 32 EOAD patients, and 34 healthy controls were entered into the study. Patients were tested on the Addenbrooke's Cognitive Examination (ACE-R), consisting of subscales in memory and visuospatial skills. PCA and EOAD patients were significantly impaired compared to controls on the ACE total score (p < 0.001), visuospatial skills (p < 0.001), and memory (p < 0.001). Consistent with the salient diagnostic deficits, PCA patients were significantly more impaired on visuospatial skills compared to EOAD patients (p < 0.001). However, there was no significant difference between patient groups in memory. Further analysis of learning, recall, and recognition components of the memory subscale showed that EOAD and PCA patients were significantly impaired compared to controls on all three components (p < 0.001), however, there was no significant difference between EOAD and PCA patients. The results of this study show that memory is impaired in the majority of PCA patients at clinical presentation. The findings suggest that memory impairment must be considered in assessment and management of PCA. Further study into memory in PCA is warranted, since the ACE-R is a brief screening tool and is likely to underestimate the presence of memory impairment.
Bisby, James A.; Burgess, Neil
The formation of associations between items and their context has been proposed to rely on mechanisms distinct from those supporting memory for a single item. Although emotional experiences can profoundly affect memory, our understanding of how it interacts with different aspects of memory remains unclear. We performed three experiments to examine…
Tillmann, Barbara; Lévêque, Yohana; Fornoni, Lesly; Albouy, Philippe; Caclin, Anne
Congenital amusia is a neuro-developmental disorder of music perception and production. The hypothesis is that the musical deficits arise from altered pitch processing, with impairments in pitch discrimination (i.e., pitch change detection, pitch direction discrimination and identification) and short-term memory. The present review article focuses on the deficit of short-term memory for pitch. Overall, the data discussed here suggest impairments at each level of processing in short-term memory tasks; starting with the encoding of the pitch information and the creation of the adequate memory trace, the retention of the pitch traces over time as well as the recollection and comparison of the stored information with newly incoming information. These impairments have been related to altered brain responses in a distributed fronto-temporal network, associated with decreased connectivity between these structures, as well as in abnormalities in the connectivity between the two auditory cortices. In contrast, amusic participants׳ short-term memory abilities for verbal material are preserved. These findings show that short-term memory deficits in congenital amusia are specific to pitch, suggesting a pitch-memory system that is, at least partly, separated from verbal memory. This article is part of a Special Issue entitled SI: Auditory working memory.
Ennis, Naomi; Roy, Sylvain; Topolovec-Vranic, Jane
Cognitive impairment may interfere with an individual's ability to function independently in the community and may increase the risk of becoming and remaining homeless. The purpose of this study was to systematically review the literature on memory deficits among people who are homeless in order to gain a better understanding of its nature, causes and prevalence. Studies that measured memory functioning as an outcome among a sample of homeless persons were included. Data on sampling, outcome measures, facet of memory explored and prevalence of memory impairment were extracted from all selected research studies. Included studies were evaluated using a critical appraisal process targetted for reviewing prevalence studies. Eleven studies were included in the review. Verbal memory was the most commonly studied facet of memory. Potential contributing factors to memory deficits among persons who are homeless were explored in seven studies. Memory deficits were common among the samples of homeless persons studied. However, there was a great deal of variation in the methodology and quality of the included studies. Conceptualisations of "homelessness" also differed across studies. There is a need for more controlled research using validated neuropsychological tools to evaluate memory impairment among people who are homeless.
Nagai, Taku; Yamada, Kiyofumi
Methamphetamine is a highly addictive drug of abuse, addiction to which has increased to epidemic proportions worldwide. It has been suggested that chronic use of methamphetamine causes long-term cognitive deficits, in addition to psychiatric signs such as hallucination and delusions, which are indistinguishable from paranoid schizophrenia. Neuroimaging studies in methamphetamine abusers have demonstrated that the loss of dopamine transporters in the striatum is related to motor and cognitive impairment. In this review, we will focus on the effect of repeated treatment with methamphetamine on cognitive function in rodents. Repeated methamphetamine treatment in mice impairs long-term recognition memory after withdrawal, which is associated with the dysfunction in dopamine D1 receptor-extracellular signal-regulated kinase 1/2 (ERK1/2) pathway in the prefrontal cortex. Methamphetamine-induced impairment of recognition memory is reversed by baclofen, clozapine, minocycline and ZSET1446. Repeated methamphetamine treatment in rats also induces impairment of spatial working memory, which is accompanied by the dysfunction of ERK1/2 pathway in the hippocampus. Repeated administration of clozapine, but not haloperidol, improves methamphetamine-induced spatial working memory impairment. These findings suggest that ERK1/2 plays an important role in memory impairments induced by repeated methamphetamine treatment. These animal models of cognitive deficits may be useful to predict the clinical effects of antipsychotics in methamphetamine psychosis and other mental disorders such as schizophrenia.
More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug
Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson's disease dementia and Alzheimer's disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders.
More, Sandeep Vasant; Kumar, Hemant; Cho, Duk-Yeon; Yun, Yo-Sep; Choi, Dong-Kug
Animal models for learning and memory have significantly contributed to novel strategies for drug development and hence are an imperative part in the assessment of therapeutics. Learning and memory involve different stages including acquisition, consolidation, and retrieval and each stage can be characterized using specific toxin. Recent studies have postulated the molecular basis of these processes and have also demonstrated many signaling molecules that are involved in several stages of memory. Most insights into learning and memory impairment and to develop a novel compound stems from the investigations performed in experimental models, especially those produced by neurotoxins models. Several toxins have been utilized based on their mechanism of action for learning and memory impairment such as scopolamine, streptozotocin, quinolinic acid, and domoic acid. Further, some toxins like 6-hydroxy dopamine (6-OHDA), 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and amyloid-β are known to cause specific learning and memory impairment which imitate the disease pathology of Parkinson’s disease dementia and Alzheimer’s disease dementia. Apart from these toxins, several other toxins come under a miscellaneous category like an environmental pollutant, snake venoms, botulinum, and lipopolysaccharide. This review will focus on the various classes of neurotoxin models for learning and memory impairment with their specific mechanism of action that could assist the process of drug discovery and development for dementia and cognitive disorders. PMID:27598124
Zhu, Biao; Dong, Yuanlin; Xu, Zhipeng; Gompf, Heinrich S; Ward, Sarah A P; Xue, Zhanggang; Miao, Changhong; Zhang, Yiying; Chamberlin, Nancy L; Xie, Zhongcong
Hospitalized patients can develop cognitive function decline, the mechanisms of which remain largely to be determined. Sleep disturbance often occurs in hospitalized patients, and neuroinflammation can induce learning and memory impairment. We therefore set out to determine whether sleep disturbance can induce neuroinflammation and impairment of learning and memory in rodents. Five to 6-month-old wild-type C57BL/6J male mice were used in the studies. The mice were placed in rocking cages for 24 h, and two rolling balls were present in each cage. The mice were tested for learning and memory function using the Fear Conditioning Test one and 7 days post-sleep disturbance. Neuroinflammation in the mouse brain tissues was also determined. Of the Fear Conditioning studies at one day and 7 days after sleep disturbance, twenty-four hour sleep disturbance decreased freezing time in the context test, which assesses hippocampus-dependent learning and memory; but not the tone test, which assesses hippocampus-independent learning and memory. Sleep disturbance increased pro-inflammatory cytokine IL-6 levels and induced microglia activation in the mouse hippocampus, but not the cortex. These results suggest that sleep disturbance induces neuroinflammation in the mouse hippocampus, and impairs hippocampus-dependent learning and memory in mice. Pending further studies, these findings suggest that sleep disturbance-induced neuroinflammation and impairment of learning and memory may contribute to the development of cognitive function decline in hospitalized patients.
Kuhlmann, Sabrina; Piel, Marcel; Wolf, Oliver T
Glucocorticoids (GCs) are known to modulate memory in animals and humans. One popular model suggests that stress or GC treatment enhances memory consolidation while impairing delayed memory retrieval. Studies in humans have documented that treatment with GCs impairs delayed memory retrieval. Similar alterations after exposure to stress have not been observed thus far. In the present study, 19 young healthy male subjects were exposed to either a standardized psychosocial laboratory stressor (Trier Social Stress Test) or a control condition in a crossover manner. After both treatments, retrieval of a word list (learned 24 h earlier) containing 10 neutral, 10 negative, and 10 positive words was tested. The stressor induced a significant increase in salivary free cortisol and a decrease in mood. Memory retrieval (free recall) was significantly impaired after the stress condition. Follow-up analysis revealed that negative and positive words (i.e., emotionally arousing words) were affected, whereas no effect was observed for neutral words. No changes were detected for cued recall, working memory, or attention. The present study thus demonstrates that psychosocial stress impairs memory retrieval in humans and suggests that emotionally arousing material is especially sensitive to this effect.
Waring, J D; Dimsdale-Zucker, H R; Flannery, S; Budson, A E; Kensinger, E A
Young and older adults experience benefits in attention and memory for emotional compared to neutral information, but this memory benefit is greatly diminished in Alzheimer's disease (AD). Little is known about whether this impairment arises early or late in the time course between healthy aging and AD. This study compared memory for positive, negative, and neutral items with neutral backgrounds between patients with mild cognitive impairment (MCI) and healthy older adults. We also used a divided attention condition in older adults as a possible model for the deficits observed in MCI patients. Results showed a similar pattern of selective memory for emotional items while forgetting their backgrounds in older adults and MCI patients, but MCI patients had poorer memory overall. Dividing attention during encoding disproportionately reduced memory for backgrounds (versus items) relative to a full attention condition. Participants performing in the lower half on the divided attention task qualitatively and quantitatively mirrored the results in MCI patients. Exploratory analyses comparing lower- and higher-performing MCI patients showed that only higher-performing MCI patients had the characteristic scene memory pattern observed in healthy older adults. Together, these results suggest that the effects of emotion on memory are relatively well preserved for patients with MCI, although emotional memory patterns may start to be altered once memory deficits become more pronounced.
Smith, Alexandra E; Slivicki, Richard A; Hohmann, Andrea G; Crystal, Jonathon D
Chemotherapeutic agents are widely used to treat patients with systemic cancer. The efficacy of these therapies is undermined by their adverse side-effect profiles such as cognitive deficits that have a negative impact on the quality of life of cancer survivors. Cognitive side effects occur across a variety of domains, including memory, executive function, and processing speed. Such impairments are exacerbated under cognitive challenges and a subgroup of patients experience long-term impairments. Episodic memory in rats can be examined using a source memory task. In the current study, rats received paclitaxel, a taxane-derived chemotherapeutic agent, and learning and memory functioning was examined using the source memory task. Treatment with paclitaxel did not impair spatial and episodic memory, and paclitaxel treated rats were not more susceptible to cognitive challenges. Under conditions in which memory was not impaired, paclitaxel treatment impaired learning of new rules, documenting a decreased sensitivity to changes in experimental contingencies. These findings provide new information on the nature of cancer chemotherapy-induced cognitive impairments, particularly regarding the incongruent vulnerability of episodic memory and new learning following treatment with paclitaxel.
Bloemer, Jenna; Bhattacharya, Subhrajit; Amin, Rajesh; Suppiramaniam, Vishnu
Insulin is secreted from the β-cells of the pancreas and helps maintain glucose homeostasis. Although secreted peripherally, insulin also plays a profound role in cognitive function. Increasing evidence suggests that insulin signaling in the brain is necessary to maintain health of neuronal cells, promote learning and memory, decrease oxidative stress, and ultimately increase neuronal survival. This chapter summarizes the different facets of insulin signaling necessary for learning and memory and additionally explores the association between cognitive impairment and central insulin resistance. The role of impaired insulin signaling in the advancement of cognitive dysfunction is relevant to the current debate of whether the shared pathophysiological mechanisms between diabetes and cognitive impairment implicate a direct relationship. Here, we summarize a vast amount of literature that suggests a strong association between impaired brain insulin signaling and cognitive impairment.
Alzoubi, Karem H; Khabour, Omar F; Albawaana, Amal S; Alhashimi, Farah H; Athamneh, Rabaa Y
Sleep deprivation is associated with oxidative stress that causes learning and memory impairment. Tempol is a nitroxide compound that promotes the metabolism of many reactive oxygen species (ROS) and has antioxidant and neuroprotective effect. The current study investigated whether chronic administration of tempol can overcome oxidative stress and prevent learning and memory impairment induced by sleep deprivation. Sleep deprivation was induced in rats using multiple platform model. Tempol was administered to rats via oral gavages. Behavioral studies were conducted to test the spatial learning and memory using radial arm water maze. The hippocampus was dissected; antioxidant biomarkers (GSH, GSSG, GSH/GSSG ratio, GPx, SOD, and catalase) were assessed. The result of this project revealed that chronic sleep deprivation impaired both short and long term memory (P<0.05), while tempol treatment prevented such effect. Furthermore, tempol normalized chronic sleep deprivation induced reduction in the hippocampus activity of catalase, GPx, and SOD (P<0.05). Tempol also enhanced the ratio of GSH/GSSG in chronically sleep deprived rats treated with tempol as compared with only sleep deprived rats (P<0.05). In conclusion chronic sleep deprivation induced memory impairment, and treatment with tempol prevented this impairment probably through normalizing antioxidant mechanisms in the hippocampus.
Singh, Rumani; Lakhanpal, Dinesh; Kumar, Sushil; Sharma, Sandeep; Kataria, Hardeep; Kaur, Manpreet; Kaur, Gurcharan
Lifelong dietary restriction (DR) is known to have many potential beneficial effects on brain function as well as delaying the onset of neurological diseases. In the present investigation, the effect of late-onset short-term intermittent fasting dietary restriction (IF-DR) regimen was studied on motor coordination and cognitive ability of ageing male rats. These animals were further used to estimate protein carbonyl content and mitochondrial complex I-IV activity in different regions of brain and peripheral organs, and the degree of age-related impairment and reversion by late-onset short-term IF-DR was compared with their levels in 3-month-old young rats. The results of improvement in motor coordination by rotarod test and cognitive skills by Morris water maze in IF-DR rats were found to be positively correlated with the decline in the oxidative molecular damage to proteins and enhanced mitochondrial complex IV activity in different regions of ageing brain as well as peripheral organs. The work was further extended to study the expression of synaptic plasticity-related proteins, such as synaptophysin, calcineurin and CaM kinase II to explore the molecular basis of IF-DR regimen to improve cognitive function. These results suggest that even late-onset short-term IF-DR regimen have the potential to retard age-associated detrimental effects, such as cognitive and motor performance as well as oxidative molecular damage to proteins.
Zhu, Zijian; Wang, Yingying; Cao, Zhijun; Chen, Biqing; Cai, Huaqian; Wu, Yanhong; Rao, Yi
Memory is a dynamic process. While memory becomes increasingly resistant to interference after consolidation, a brief reactivation renders it unstable again. Previous studies have shown that interference, when applied upon reactivation, impairs the consolidated memory, presumably by disrupting the reconsolidation of the memory. However, attempts have failed in disrupting human declarative memory, raising a question about whether declarative memory becomes unstable upon reactivation. Here, we used a double-cue/one-target paradigm, which associated the same target with two different cues in initial memory formation. Only one cue/target association was later reactivated and treated with behavioral interference. Our results showed, for the first time, that reactivation-coupled interference caused cue-independent memory impairment that generalized to other cues associated with the memory. Critically, such memory impairment appeared immediately after interference, before the reconsolidation process was completed, suggesting that common manipulations of reactivation-coupled interference procedures might disrupt other processes in addition to the reconsolidation process in human declarative memory.
Coppin, Géraldine; Nolan-Poupart, Sarah; Jones-Gotman, Marilyn; Small, Dana M.
Obesity has been associated with impaired executive functions including working memory. Less explored is the influence of obesity on learning and memory. In the current study we assessed stimulus reward association learning, explicit learning and memory and working memory in healthy weight, overweight and obese individuals. Explicit learning and memory did not differ as a function of group. In contrast, working memory was significantly and similarly impaired in both overweight and obese individuals compared to the healthy weight group. In the first reward association learning task the obese, but not healthy weight or overweight participants consistently formed paradoxical preferences for a pattern associated with a negative outcome (fewer food rewards). To determine if the deficit was specific to food reward a second experiment was conducted using money. Consistent with experiment 1, obese individuals selected the pattern associated with a negative outcome (fewer monetary rewards) more frequently than healthy weight individuals and thus failed to develop a significant preference for the most rewarded patterns as was observed in the healthy weight group. Finally, on a probabilistic learning task, obese compared to healthy weight individuals showed deficits in negative, but not positive outcome learning. Taken together, our results demonstrate deficits in working memory and stimulus reward learning in obesity and suggest that obese individuals are impaired in learning to avoid negative outcomes. PMID:25447070
Yamazaki, Daisuke; Horiuchi, Junjiro; Ueno, Kohei; Ueno, Taro; Saeki, Shinjiro; Matsuno, Motomi; Naganos, Shintaro; Miyashita, Tomoyuki; Hirano, Yukinori; Nishikawa, Hiroyuki; Taoka, Masato; Yamauchi, Yoshio; Isobe, Toshiaki; Honda, Yoshiko; Kodama, Tohru; Masuda, Tomoko; Saitoe, Minoru
Several aging phenotypes, including age-related memory impairment (AMI), are thought to be caused by cumulative oxidative damage. In Drosophila, age-related impairments in 1 hr memory can be suppressed by reducing activity of protein kinase A (PKA). However, the mechanism for this effect has been unclear. Here we show that decreasing PKA suppresses AMI by reducing activity of pyruvate carboxylase (PC), a glial metabolic enzyme whose amounts increase upon aging. Increased PC activity causes AMI through a mechanism independent of oxidative damage. Instead, increased PC activity is associated with decreases in D-serine, a glia-derived neuromodulator that regulates NMDA receptor activity. D-serine feeding suppresses both AMI and memory impairment caused by glial overexpression of dPC, indicating that an oxidative stress-independent dysregulation of glial modulation of neuronal activity contributes to AMI in Drosophila.
Squire, Larry R.
Studies of memory impairment in humans and experimental animals have been fundamental to learning about the organization of memory and its cellular and molecular substrates. When memory impairment occurs, especially after perturbations of the nervous system, the question inevitably arises whether the impairment reflects impaired information…
Quesada, A A; Wiemers, U S; Schoofs, D; Wolf, O T
Negative consequences of stress on working memory and delayed memory retrieval have been observed in adult humans. Little is known about the occurrence of similar effects in children. Forty-four German full-term children, aged 8-10 years, were randomly assigned to a stressful (Trier Social Stress Test for Children--TSST-C) or to a non-stressful control condition. Afterwards, delayed memory retrieval was tested using a computerized version of the well-known card game "Memory". It contained positive, neutral and negative stimuli. In addition, working memory of verbal and non-verbal material was assessed. The stressed children showed pronounced cortisol increases accompanied by a decrease in mood. Children exposed to the stressor performed poorer in the delayed memory retrieval test (memory card game). They committed more errors. No differences were found for working memory. The stress-induced memory retrieval impairment mirrors findings in adults. In contrast, the missing working memory effects could suggest developmental differences in stress sensitivity.
Barber, Sarah J; Mather, Mara
Negative stereotypes about aging can impair older adults' memory via stereotype threat; however, the mechanisms underlying this phenomenon are unclear. In two experiments, we tested competing predictions derived from two theoretical accounts of stereotype threat: executive-control interference and regulatory fit. Older adults completed a working memory test either under stereotype threat about age-related memory declines or not under such threat. Monetary incentives were manipulated such that recall led to gains or forgetting led to losses. The executive-control-interference account predicts that stereotype threat decreases the availability of executive-control resources and hence should impair working memory performance. The regulatory-fit account predicts that threat induces a prevention focus, which should impair performance when gains are emphasized but improve performance when losses are emphasized. Results were consistent only with the regulatory-fit account. Although stereotype threat significantly impaired older adults' working memory performance when remembering led to gains, it significantly improved performance when forgetting led to losses.
Kuypers, Kim P. C.; Theunissen, Eef L.; van Wel, Janelle H. P.; de Sousa Fernandes Perna, Elizabeth B.; Linssen, Anke; Sambeth, Anke; Schultz, Benjamin G.; Ramaekers, Johannes G.
Background Ecstasy use has been associated with short-term and long-term memory deficits on a standard Word Learning Task (WLT). The clinical relevance of this has been debated and is currently unknown. The present study aimed at evaluating the clinical relevance of verbal memory impairment in Ecstasy users. To that end, clinical memory impairment was defined as decrement in memory performance that exceeded the cut-off value of 1.5 times the standard deviation of the average score in the healthy control sample. The primary question was whether being an Ecstasy user (E-user) was predictive of having clinically deficient memory performance compared to a healthy control group. Methods WLT data were pooled from four experimental MDMA studies that compared memory performance during placebo and MDMA intoxication. Control data were taken from healthy volunteers with no drug use history who completed the WLT as part of a placebo-controlled clinical trial. This resulted in a sample size of 65 E-users and 65 age- and gender-matched healthy drug-naïve controls. All participants were recruited by similar means and were tested at the same testing facilities using identical standard operating procedures. Data were analyzed using linear mixed-effects models, Bayes factor, and logistic regressions. Results Findings were that verbal memory performance of placebo-treated E-users did not differ from that of controls, and there was substantial evidence in favor of the null hypothesis. History of use was not predictive of memory impairment. During MDMA intoxication of E-users, verbal memory was impaired. Conclusion The combination of the acute and long-term findings demonstrates that, while clinically relevant memory impairment is present during intoxication, it is absent during abstinence. This suggests that use of Ecstasy/MDMA does not lead to clinically deficient memory performance in the long term. Additionally, it has to be investigated whether the current findings apply to more
Puetz, Julia; Grohmann, Svenja; Metternich, Birgitta; Kloepfer, Corinna; Feige, Bernd; Nissen, Christoph; Riemann, Dieter; Hüll, Michael; Hornyak, Magdolna
Functional memory disorder (FMD) is characterized by mnestic and attentional deficits without symptoms of mild cognitive impairment or dementia. FMD usually develops in subjects with high psychosocial stress level and is classified to the somatoform disorders. We assessed memory performance (procedural mirror tracing task, declarative visual and verbal memory task) and other cognitive functions before and after one night of sleep in 12 FMD patients (mean age: 51.7 yrs, 7 females) and 12 healthy subjects matched for age, gender and IQ. Memory performance and other neurocognitive tasks did not differ between the groups at baseline. After one night of sleep, FMD patients showed an impairment of declarative memory consolidation compared to healthy subjects (visual task: p=0.004; verbal task: p=0.039). Spectral analysis of sleep-EEG indicated an increased cortical excitation in FMD. We hypothesize that a hyperarousal state in FMD might contribute to sleep disturbance implicating negative effects on declarative memory consolidation.
Ricarte, J J; Hernández, J V; Latorre, J M; Danion, J M; Berna, F
Although patients with schizophrenia exhibit autobiographical memory impairment, which is considered to be a limiting factor in their daily life, the mechanisms underlying such impairment have been rarely studied. In the current study, we investigate whether rumination and, in particular, brooding, which is a form of maladaptive repetitive thinking, may be linked to the difficulty that patients with schizophrenia experience when attempting to access specific autobiographical memories. Our results indicate that patients reported less specific autobiographical memories compared to control participants. Patients also displayed a higher level of brooding and had more depressive symptoms. According to the CaR-FA-X model (Williams et al., 2007), depression and brooding were associated with memory specificity in control participants. In contrast, neither depression nor brooding was correlated with memory specificity in patients. These results suggest that depression and rumination may not be directly related to patients' difficulty to recall specific memories and that other factors, such as metacognitive deficits, must first be considered when seeking interventions aimed to improve autobiographical memory in patients with schizophrenia.
Ryu, Seon Young; Lee, Sang Bong; Kim, Tae Woo; Lee, Taek Jun
Memory complaints are a frequent phenomenon in elderly individuals and can lead to opportunistic help-seeking behavior. The aim of this study was to compare different aspects of memory complaints (i.e., prospective versus retrospective complaints) in individuals with subjective cognitive impairment (SCI), amnestic mild cognitive impairment (aMCI), and mild Alzheimer's disease (AD). The study included a total of 115 participants (mean age: 68.82 ± 8.83 years) with SCI (n = 34), aMCI (n = 46), and mild AD (n = 35). Memory complaints were assessed using the Prospective and Retrospective Memory Questionnaire (PRMQ), which consists of 16 items that describe everyday memory failure of both prospective memory (PM) and retrospective memory (RM). For aMCI and AD subjects, informants also completed an informant-rating of the PRMQ. All participants completed detailed neuropsychological tests. Results show that PM complaints were equivalent among the three groups. However, RM complaints differed. Specifically, RM complaints in aMCI were higher than SCI, but similar to AD. Informant-reported memory complaints were higher for AD than aMCI. Our study suggests that RM complaints of memory complaints may be helpful in discriminating between SCI and aMCI, but both PM and RM complaints are of limited value in differentiating aMCI from AD.
Nichols, Sharon; Jones, Wendy; Roman, Mary J.; Wulfeck, Beverly; Delis, Dean C.; Reilly, Judy; Bellugi, Ursula
Profiles of verbal learning and memory performance were compared for typically developing children and for four developmental disorders characterized by different patterns of language functioning: specific language impairment, early focal brain damage, Williams Syndrome, and Down Syndrome. A list-learning task was used that allowed a detailed…
Auksztulewicz, Ryszard; Spitzer, Bernhard; Goltz, Dominique; Blankenburg, Felix
Numerous studies in animals and humans have related central aspects of somatosensory working memory function to neural activity in the inferior frontal gyrus (IFG). However, as previous studies have almost exclusively used correlational analyses, the question whether sustained neural activity in the IFG is causally involved in successful maintenance of somatosensory information remains unanswered. We used an online repetitive transcranial magnetic stimulation (rTMS) protocol to disrupt neuronal activity in the IFG while participants were maintaining tactile information throughout the delay for later comparison against a probe stimulus. rTMS impaired participants' performance in the working memory task, but not in a physically matched perceptual control task. Targeting the IFG in either hemisphere led to comparable working memory impairment. Our results show that the neural activity in the IFG plays a causal role in successful maintenance of somatosensory information.
Kulatunga, R. D. H.; Dave, Alankruta R.; Baghel, Madhav Singh
Aging has become one of the distinctive demographic phenomena in the 21st century and its social, economic and health implications are the most challenging issues. Senile Memory Impairment is a common condition characterized by mild symptoms of cognitive decline and occurs as a part of the normal aging process. It can be correlated to “Jarajanya Smrtibhramsha” according to Ayurveda. The present study deals with the efficacy of Guduchyadi Medhya Rasayana on Senile Memory Impairment. A total of 138 patients aged in between 55–75 years were registered and randomly divided into two groups as the trial and control groups. The drugs were administered for 3. The trial drug showed memory enhancement, anti-stress, anti-depressant and anxiolytic properties. The trial group showed better results in the management compared to the control group. PMID:23559791
Garcia, Vanessa Athaíde; Souza de Freitas, Betânia; Busato, Stefano Boemler; D'avila Portal, Bernardo Chaves; Piazza, Francisco Correa; Schröder, Nadja
Modafinil is a wake-promoting drug and has been approved for the treatment of excessive daytime sleepiness in narcolepsy and obstructive sleep apnea. Modafinil was shown to improve learning and memory in rodents, and to reverse memory deficits induced by sleep deprivation or stress. However, depending on the memory paradigm used, modafinil might also impair memory. We aimed to investigate the effects of modafinil on memory consolidation and retrieval for object recognition and inhibitory avoidance in naïve adult rats. We also investigated whether acute or chronic administration of modafinil would reverse memory deficits induced by iron overload, a model of memory impairment related to neurodegenerative disorders. Adult naïve rats received modafinil (0.0, 0.75, 7.5 or 75 mg/kg) either immediately after training or 1 h prior to testing in object recognition or inhibitory avoidance. Iron-treated rats received modafinil immediately after training in object recognition. In order to investigate the effects of chronic modafinil, iron-treated rats received daily injections of modafinil for 17 days, and 24 h later they were trained in object recognition or inhibitory avoidance. Acute modafinil does not affect memory consolidation or retrieval in naive rats. A single injection of modafinil at the highest dose was able to recover recognition memory in iron-treated rats. Chronic modafinil completely recovered iron-induced recognition memory and emotional memory deficits. Additional preclinical and clinical studies are necessary in order to support the applicability of modafinil in recovering memory impairment associated with neurodegenerative disorders.
Guimond, Synthia; Hawco, Colin; Lepage, Martin
Schizophrenia patients have significant memory difficulties that have far-reaching implications in their daily life. These impairments are partly attributed to an inability to self-initiate effective memory encoding strategies, but its core neurobiological correlates remain unknown. The current study addresses this critical gap in our knowledge of episodic memory impairments in schizophrenia. Schizophrenia patients (n = 35) and healthy controls (n = 23) underwent a Semantic Encoding Memory Task (SEMT) during an fMRI scan. Brain activity was examined for conditions where participants were a) prompted to use semantic encoding strategies, or b) not prompted but required to self-initiate such strategies. When prompted to use semantic encoding strategies, schizophrenia patients exhibited similar recognition performance and brain activity as healthy controls. However, when required to self-initiate these strategies, patients had significant reduced recognition performance and brain activity in the left dorsolateral prefrontal cortex, as well as in the left temporal gyrus, left superior parietal lobule, and cerebellum. When patients were divided based on performance on the SEMT, the subgroup with more severe deficits in self-initiation also showed greater reduction in left dorsolateral prefrontal activity. These results suggest that impaired self-initiation of elaborative encoding strategies is a driving feature of memory deficits in schizophrenia. We also identified the neural correlates of impaired self-initiation of semantic encoding strategies, in which a failure to activate the left dorsolateral prefrontal cortex plays a key role. These findings provide important new targets in the development of novel treatments aiming to improve memory and ultimately patients' outcome.
Liu, Hu; Wang, Ting; Dai, Wei; Jiang, Zheng; Li, Yuan-hai; Liu, Xue-sheng
Abundant evidence indicates that propofol profoundly affects memory processes, although its specific effects on memory retrieval have not been clarified. A recent study has indicated that hippocampal glycogen synthase kinase-3β (GSK-3β) activity affects memory. Constitutively active GSK-3β is required for memory retrieval, and propofol has been shown to inhibit GSK-3β. Thus, the present study examined whether propofol affects memory retrieval, and, if so, whether that effect is mediated through altered GSK-3β activity. Adult Sprague-Dawley rats were trained on a Morris water maze task (eight acquisition trials in one session) and subjected under the influence of a subhypnotic dose of propofol to a 24-hour probe trial memory retrieval test. The results showed that rats receiving pretest propofol (25 mg/kg) spent significantly less time in the target quadrant but showed no change in locomotor activity compared with those in the control group. Memory retrieval was accompanied by reduced phosphorylation of the serine-9 residue of GSK-3β in the hippocampus, whereas phosphorylation of the tyrosine-216 residue was unaffected. However, propofol blocked this retrieval-associated serine-9 phosphorylation. These findings suggest that subhypnotic propofol administration impairs memory retrieval and that the amnestic effects of propofol may be mediated by attenuated GSK-3β signaling in the hippocampus. PMID:28197192
Liu, Hu; Wang, Ting; Dai, Wei; Jiang, Zheng; Li, Yuan-Hai; Liu, Xue-Sheng
Abundant evidence indicates that propofol profoundly affects memory processes, although its specific effects on memory retrieval have not been clarified. A recent study has indicated that hippocampal glycogen synthase kinase-3β (GSK-3β) activity affects memory. Constitutively active GSK-3β is required for memory retrieval, and propofol has been shown to inhibit GSK-3β. Thus, the present study examined whether propofol affects memory retrieval, and, if so, whether that effect is mediated through altered GSK-3β activity. Adult Sprague-Dawley rats were trained on a Morris water maze task (eight acquisition trials in one session) and subjected under the influence of a subhypnotic dose of propofol to a 24-hour probe trial memory retrieval test. The results showed that rats receiving pretest propofol (25 mg/kg) spent significantly less time in the target quadrant but showed no change in locomotor activity compared with those in the control group. Memory retrieval was accompanied by reduced phosphorylation of the serine-9 residue of GSK-3β in the hippocampus, whereas phosphorylation of the tyrosine-216 residue was unaffected. However, propofol blocked this retrieval-associated serine-9 phosphorylation. These findings suggest that subhypnotic propofol administration impairs memory retrieval and that the amnestic effects of propofol may be mediated by attenuated GSK-3β signaling in the hippocampus.
Silver, Henry; Bilker, Warren B
Memory is impaired in schizophrenia patients but it is not clear whether this is specific to the illness and whether different types of memory (verbal and nonverbal) or memories in different cognitive domains (executive, object recognition) are similarly affected. To study relationships between memory impairments and schizophrenia we compared memory functions in 77 schizophrenia patients, 58 elderly healthy individuals and 41 young healthy individuals. Tests included verbal associative and logical memory and memory in executive and object recognition domains. We compared relationships of memory functions to each other and to other cognitive functions including psychomotor speed and verbal and spatial working memory. Compared to the young healthy group, schizophrenia patients and elderly healthy individuals showed similar severe impairment in logical memory and in the ability to learn new associations (NAL), and similar but less severe impairment in spatial working memory and executive and object memory. Verbal working memory was significantly more impaired in schizophrenia patients than in the healthy elderly. Verbal episodic memory impairment in schizophrenia may share common mechanisms with similar impairment in healthy aging. Impairment in verbal working memory in contrast may reflect mechanisms specific to schizophrenia. Study of verbal explicit memory impairment tapped by the NAL index may advance understanding of abnormal hippocampus dependent mechanisms common to schizophrenia and aging.
Tzeng, Wen-Yu; Chang, Wan-Ting; Chuang, Jia-Ying; Lin, Kuey-Yin; Cherng, Chianfang G; Yu, Lung
Two hypotheses were tested in this study. First, blockade of neural activity by lidocaine immediately following the retrieval of a memory may impair the reconsolidation and subsequent expression of that memory. Second, a non-retrieved memory would not be affected by this lidocaine treatment. Since the basolateral nucleus of the amygdala (BLA) is involved in emotion-related memory, an intra-BLA lidocaine infusion was used immediately after the retrieval of two emotion-related memories, the step-through passive avoidance response (PA) and cocaine-induced conditioned place preference (CPP). Intra-BLA lidocaine infusion immediately after cocaine-induced CPP retrieval diminished CPP magnitude in retests. However, intra-BLA lidocaine infusion alone did not affect cocaine-induced CPP performance. Intra-BLA lidocaine infusion immediately after PA retrieval decreased PA performance in retests. Omission of PA retrieval procedure, intra-BLA lidocaine infusion did not affect subsequent PA performance. Surprisingly, intra-BLA lidocaine infusion immediately following the retrieval of PA or cocaine-induced CPP diminished both PA and cocaine-induced CPP performance in the retests. Finally, Fos-staining results revealed that a number of BLA neurons were activated by the retrieval of both cocaine-induced CPP and PA. We conclude that inactivation of neural activity in BLA immediately following retrieval of a fear or cocaine-conditioned memory can impair subsequent expression of both memories. More importantly, retrieval of a memory does not seem to be an absolute condition for rapidly changing the memory.
Collins, Anne G E; Brown, Jaime K; Gold, James M; Waltz, James A; Frank, Michael J
Previous research has shown that patients with schizophrenia are impaired in reinforcement learning tasks. However, behavioral learning curves in such tasks originate from the interaction of multiple neural processes, including the basal ganglia- and dopamine-dependent reinforcement learning (RL) system, but also prefrontal cortex-dependent cognitive strategies involving working memory (WM). Thus, it is unclear which specific system induces impairments in schizophrenia. We recently developed a task and computational model allowing us to separately assess the roles of RL (slow, cumulative learning) mechanisms versus WM (fast but capacity-limited) mechanisms in healthy adult human subjects. Here, we used this task to assess patients' specific sources of impairments in learning. In 15 separate blocks, subjects learned to pick one of three actions for stimuli. The number of stimuli to learn in each block varied from two to six, allowing us to separate influences of capacity-limited WM from the incremental RL system. As expected, both patients (n = 49) and healthy controls (n = 36) showed effects of set size and delay between stimulus repetitions, confirming the presence of working memory effects. Patients performed significantly worse than controls overall, but computational model fits and behavioral analyses indicate that these deficits could be entirely accounted for by changes in WM parameters (capacity and reliability), whereas RL processes were spared. These results suggest that the working memory system contributes strongly to learning impairments in schizophrenia.
Brown, Jaime K.; Gold, James M.; Waltz, James A.; Frank, Michael J.
Previous research has shown that patients with schizophrenia are impaired in reinforcement learning tasks. However, behavioral learning curves in such tasks originate from the interaction of multiple neural processes, including the basal ganglia- and dopamine-dependent reinforcement learning (RL) system, but also prefrontal cortex-dependent cognitive strategies involving working memory (WM). Thus, it is unclear which specific system induces impairments in schizophrenia. We recently developed a task and computational model allowing us to separately assess the roles of RL (slow, cumulative learning) mechanisms versus WM (fast but capacity-limited) mechanisms in healthy adult human subjects. Here, we used this task to assess patients' specific sources of impairments in learning. In 15 separate blocks, subjects learned to pick one of three actions for stimuli. The number of stimuli to learn in each block varied from two to six, allowing us to separate influences of capacity-limited WM from the incremental RL system. As expected, both patients (n = 49) and healthy controls (n = 36) showed effects of set size and delay between stimulus repetitions, confirming the presence of working memory effects. Patients performed significantly worse than controls overall, but computational model fits and behavioral analyses indicate that these deficits could be entirely accounted for by changes in WM parameters (capacity and reliability), whereas RL processes were spared. These results suggest that the working memory system contributes strongly to learning impairments in schizophrenia. PMID:25297101
Cai, Wen-Hui; Blundell, Jacqueline; Han, Jie; Greene, Robert W; Powell, Craig M
Pavlovian fear conditioning provides one of the best rodent models of acquired anxiety disorders, including posttraumatic stress disorder. Injection of a variety of drugs after training in fear-conditioning paradigms can impair consolidation of fear memories. Indeed, early clinical trials suggest that immediate administration of such drugs after a traumatic event may decrease the risk of developing posttraumatic stress disorder in humans (Pitman et al., 2002; Vaiva et al., 2003). The use of such a treatment is limited by the difficulty of treating every patient at risk and by the difficulty in predicting which patients will experience chronic adverse consequences. Recent clinical trials suggest that administration of glucocorticoids may have a beneficial effect on established posttraumatic stress disorder (Aerni et al., 2004) and specific phobia (Soravia et al., 2006). Conversely, glucocorticoid administration after training is known to enhance memory consolidation (McGaugh and Roozendaal, 2002; Roozendaal, 2002). From a clinical perspective, enhancement of a fear memory or a reactivated fear memory would not be desirable. We report here that when glucocorticoids are administered immediately after reactivation of a contextual fear memory, subsequent recall is significantly diminished. Additional experiments support the interpretation that glucocorticoids not only decrease fear memory retrieval but, in addition, augment consolidation of fear memory extinction rather than decreasing reconsolidation. These findings provide a rodent model for a potential treatment of established acquired anxiety disorders in humans, as suggested by others (Aerni et al., 2004; Schelling et al., 2004), based on a mechanism of enhanced extinction.
Marton, Klara; Campanelli, Luca; Farkas, Lajos
Children with primary language impairment (LI) show a deficit in processing different grammatical structures, verb inflections, and syntactically complex sentences among other things (Clahsen–Hansen 1997; Leonard et al. 1997). Cross-linguistic research has shown that the pattern of performance is language-specific. We examined grammatical sensitivity to word order and agreement violations in 50 Hungarian-speaking children with and without LI. The findings suggest a strong association between sensitivity to grammatical violations and working memory capacity. Variations in working memory performance predicted grammatical sensitivity. Hungarian participants with LI exhibited a weakness in detecting both agreement and word order violations. PMID:23440891
Alves, Fátima; Resende, Flávia; Salomé Pinho, Maria
The diversion paradigm was created in the context of explaining the effect of the instruction to forget some recently encoded material in the list-method of the directed forgetting paradigm. The current study of healthy older adults employed the diversion paradigm with two main goals: to determine whether thinking about an autobiographical memory interferes with the recall of recently encoded information and to explore whether the degree of forgetting depends on the temporal distance created by the diversionary thought. Ninety non-institutionalized Portuguese older adults (47 females and 43 males), aged 65–69 years, with education levels of between 3 and 6 years participated in this study. The exclusion criteria were as follows: presence of depressive symptomatology (assessed with the Geriatric Depression Scale-30) and global cognitive deterioration (assessed with the Mini–Mental State Examination). Concerning the diversion paradigm, one group was instructed to think about an autobiographical event (remembering one’s childhood home or the last party that one had attended) after studying one word list (List 1) and before viewing the second word list (List 2). After a brief distraction task, the participant had to recall the words from both of the studied lists. In the control group, the procedure was the same, but the diversionary thought was substituted by a speed reading task. The obtained results showed the amnesic effect of diversionary thought but did not show a greater degree of forgetting when the autobiographical events in the diversionary thoughts were temporally more distant. Considering the practical implications of these results, this study alerts us to the importance of promoting strategies that enable older adults to better remember important information and effectively forget irrelevant information. PMID:26539106
Hsu, Wei-Lun; Ma, Yun-Li; Hsieh, Ding-You; Liu, Yen-Chen; Lee, Eminy Hy
Signal transducer and activator of transcription-1 (STAT1) has an important role in inflammation and the innate immune response, but its role in the central nervous system is less well understood. Here, we examined the role of STAT1 in spatial learning and memory, and assessed the involvement of STAT1 in mediating the memory-impairing effect of amyloid-beta (Aβ). We found that water maze training downregulated STAT1 expression in the rat hippocampal CA1 area, and spatial learning and memory function was enhanced in Stat1-knockout mice. Conversely, overexpression of STAT1 impaired water maze performance. STAT1 strongly upregulated the expression of the extracellular matrix protein laminin β1 (LB1), which also impaired water maze performance in rats. Furthermore, Aβ impaired spatial learning and memory in association with a dose-dependent increase in STAT1 and LB1 expression, but knockdown of STAT1 and LB1 both reversed this effect of Aβ. This Aβ-induced increase in STAT1 and LB1 expression was also associated with a decrease in the expression of the N-methyl-D-aspartate receptor (NMDAR) subunits, NR1, and NR2B. Overexpression of NR1 or NR2B or exogenous application of NMDA reversed Aβ-induced learning and memory deficits as well as Aβ-induced STAT1 and LB1 expression. Our results demonstrate that STAT1 negatively regulates spatial learning and memory through transcriptional regulation of LB1 expression. We also identified a novel mechanism for Aβ pathogenesis through STAT1 induction. Notably, impairment of spatial learning and memory by this STAT1-mediated mechanism is independent of cAMP responsive element-binding protein signaling.
Nakamoto, Fumiko Kusunoki; Tsutsumiuchi, Michiko; Maeda, Meiko Hashimoto; Uesaka, Yoshikazu; Takeda, Katsuhiko
We reported a patient with a right cerebellar infarction who showed anterograde amnesia. Cognitive dysfunction caused by cerebellar lesions was called cerebellar cognitive affective syndrome, and deactivation of the contralateral prefrontal cortex function due to disconnections of cerebello-cerebral fiber tracts have been hypothesized as mechanism underlying the syndrome. The episodic memory impairment, however, could not be supported by the same mechanism because the prefrontal lesions cannot cause amnesia syndrome. The feature of the impairment of our patient was similar to that of diencephalic amnesia, and a single photon emission computed tomography study showed a relative hypoperfusion in the right cerebellar hemisphere and left anterior thalamus. We considered that the memory deficit was caused by the dysfunction of the thalamus, which is a relay center of the cerebello-cerebral connectivity network.
Klein-Koerkamp, Yanica; Baciu, Monica; Hot, Pascal
Patients with early atrophy of both limbic structures involved in memory and emotion processing in Alzheimer's disease (AD) provide a unique clinical population for investigating how emotion is able to modulate retention processes. This review focuses on the emotional enhancement effect (EEE), defined as the improvement of memory for emotional events compared with neutral ones. The assessment of the EEE for different memory systems in AD suggests that the EEE could be preserved under specific retrieval instructions. The first part of this review examines these data in light of compelling evidence that the amygdala can modulate processes of hippocampus-dependent memory. We argue that the EEE could be a useful paradigm to reduce impairment in episodic memory tasks. In the second part, we discuss theoretical consequences of the findings in favor of an EEE, according to which a compensatory mechanism in patients with AD solicits greater amygdala functioning or additional networks, even when amygdala atrophy is present. These considerations emphasize the relevance of investigating patients with AD to understand the relationship between emotion and memory processes.
Grilli, Matthew D.; Glisky, Elizabeth L.
Objective The ability to imagine an elaborative event from a personal perspective relies on a number of cognitive processes that may potentially enhance subsequent memory for the event, including visual imagery, semantic elaboration, emotional processing, and self-referential processing. In an effort to find a novel strategy for enhancing memory in memory-impaired individuals with neurological damage, the present study investigated the mnemonic benefit of a method we refer to as “self-imagining” – or the imagining of an event from a realistic, personal perspective. Method Fourteen individuals with neurologically-based memory deficits and fourteen healthy control participants intentionally encoded neutral and emotional sentences under three instructions: structural-baseline processing, semantic processing, and self-imagining. Results Findings revealed a robust “self-imagination effect” as self-imagination enhanced recognition memory relative to deep semantic elaboration in both memory-impaired individuals, F (1, 13) = 32.11, p < .001, η2 = .71, and healthy controls, F (1, 13) = 5.57, p < .05, η2 = .30. In addition, results indicated that mnemonic benefits of self-imagination were not limited by severity of the memory disorder nor were they related to self-reported vividness of visual imagery, semantic processing, or emotional content of the materials. Conclusions The findings suggest that the self-imagination effect may depend on unique mnemonic mechanisms possibly related to self-referential processing, and that imagining an event from a personal perspective makes that event particularly memorable even for those individuals with severe memory deficits. Self-imagining may thus provide an effective rehabilitation strategy for individuals with memory impairment. PMID:20873930
Smith, Colin J.; Xiong, Guoxiang; Elkind, Jaclynn A.; Putnam, Brendan; Cohen, Akiva S.
More than 2.5 million Americans suffer a traumatic brain injury (TBI) each year. Even mild to moderate TBI causes long-lasting neurological effects. Despite its prevalence, no therapy currently exists to treat the underlying cause of cognitive impairment suffered by TBI patients. Following lateral fluid percussion injury (LFPI), the most widely used experimental model of TBI, we investigated alterations in working memory and excitatory/inhibitory synaptic balance in the prefrontal cortex. LFPI impaired working memory as assessed with a T-maze behavioral task. Field excitatory postsynaptic potentials recorded in the prefrontal cortex were reduced in slices derived from brain-injured mice. Spontaneous and miniature excitatory postsynaptic currents onto layer 2/3 neurons were more frequent in slices derived from LFPI mice, while inhibitory currents onto layer 2/3 neurons were smaller after LFPI. Additionally, an increase in action potential threshold and concomitant decrease in firing rate was observed in layer 2/3 neurons in slices from injured animals. Conversely, no differences in excitatory or inhibitory synaptic transmission onto layer 5 neurons were observed; however, layer 5 neurons demonstrated a decrease in input resistance and action potential duration after LFPI. These results demonstrate synaptic and intrinsic alterations in prefrontal circuitry that may underlie working memory impairment caused by TBI. PMID:26617569
Pickel, Kerri L; Kulig, Teresa C; Bauer, Heather M
Witnesses to crimes sometimes perform cognitively demanding tasks while simultaneously observing a perpetrator. This division of attentional resources can cause witnesses to remember the perpetrator less accurately. We hypothesised that judging the veracity of a target individual can impair subsequent memory for his or her appearance and message. In Experiment 1, we demonstrated that the veracity judgement task is cognitively demanding by having participants perform a concurrent secondary task. In three additional experiments, we confirmed that witnesses who judged the veracity of a target remembered his or her appearance and message less accurately than witnesses who simply observed the target. We also extended this result by showing that suspicion amplified the memory impairment effect, apparently by inducing witnesses to allocate even more resources to the judgement task (Experiments 2a and b), and that witnesses' memory was less accurate when they used a cue within the message content rather than a nonverbal cue to judge veracity (Experiment 3). Contrary to our prediction, however, witnesses who monitored two cues versus one did not display worse memory performance.
Morris, Robin G; Nelis, Sharon M; Martyr, Anthony; Markova, Ivana; Roth, Ilona; Woods, Robert T; Whitaker, Christopher J; Clare, Linda
The study investigated different types of awareness of memory dysfunction in dementia, specifically judgements concerning memory task performance or appraisal of everyday memory functioning and also exploring the neuropsychological correlates of such awareness. This was investigated in 76 people with dementia, comprising 46 patients with Alzheimer's disease (AD) and 30 patients with vascular dementia (VaD). The Memory Awareness Rating Scale (Clare et al., 2002, Neuropsychol Rehabil, 12, 341-362) was used, which includes an Objective-Judgement Discrepancy (OJD) technique involving comparison of subjective evaluation of performance on specific memory tasks with actual performance, and a Subjective Rating Discrepancy (SRD) technique, which compares self versus informant judgement of everyday memory function. The AD and VaD groups showed lower awareness than a normal control group for both types of measures, the AD group showing less awareness than the VaD group on the OJD measure. Regression analyses supported associations for both groups between memory impairment and the OJD measure and between naming impairment and the SRD measure. The findings are discussed in terms of neurocognitive theories accounting for loss of awareness in dementia.
Schmidt, Stephen R
College students were asked about their personal memories from September 11, 2001. Consistency in reported features over a 2-month period increased as the delay between the initial test and 9/11 increased. Central features (e.g., Where were you?) were reported with greater consistency than were peripheral features (What were you wearing?) but also contained a larger proportion of reconstructive errors. In addition, highly emotional participants demonstrated poor prospective memory and relatively inconsistent memory for peripheral details, when compared with less emotional participants. Highly emotional participants were also more likely to increase the specificity of their responses over time but did not exhibit greater consistency for central details than did less emotional participants. The results demonstrated reconstructive processes in the memory for a highly consequential and emotional event and emotional impairment of memory processing of incidental details.
Krikorian, Robert; Shidler, Marcelle D; Dangelo, Krista; Couch, Sarah C; Benoit, Stephen C; Clegg, Deborah J
We randomly assigned 23 older adults with Mild Cognitive Impairment to either a high carbohydrate or very low carbohydrate diet. Following the six-week intervention period, we observed improved verbal memory performance for the low carbohydrate subjects (p = 0.01) as well as reductions in weight (p < 0.0001), waist circumference (p < 0.0001), fasting glucose (p = 0.009), and fasting insulin (p = 0.005). Level of depressive symptoms was not affected. Change in calorie intake, insulin level, and weight were not correlated with memory performance for the entire sample, although a trend toward a moderate relationship between insulin and memory was observed within the low carbohydrate group. Ketone levels were positively correlated with memory performance (p = 0.04). These findings indicate that very low carbohydrate consumption, even in the short-term, can improve memory function in older adults with increased risk for Alzheimer’s disease. While this effect may be attributable in part to correction of hyperinsulinemia, other mechanisms associated with ketosis such as reduced inflammation and enhanced energy metabolism also may have contributed to improved neurocognitive function. Further investigation of this intervention is warranted to evaluate its preventive potential and mechanisms of action in the context of early neurodegeneration. PMID:21130529
Riedel, W; Hogervorst, E; Leboux, R; Verhey, F; van Praag, H; Jolles, J
Caffeine consumption can be beneficial for cognitive functioning. Although caffeine is widely recognized as a mild CNS stimulant drug, the most important consequence of its adenosine antagonism is cholinergic stimulation, which might lead to improvement of higher cognitive functions, particularly memory. In this study, the scopolamine model of amnesia was used to test the cholinergic effects of caffeine, administered as three cups of coffee. Subjects were 16 healthy volunteers who received 250 mg caffeine and 2 mg nicotine separately, in a placebo-controlled double-blind cross-over design. Compared to placebo, nicotine attenuated the scopolamine-induced impairment of storage in short-term memory and attenuated the scopolamine-induced slowing of speed of short-term memory scanning. Nicotine also attenuated the scopolamine-induced slowing of reaction time in a response competition task. Caffeine attenuated the scopolamine-induced impairment of free recall from short- and long-term memory, quality and speed of retrieval from long-term memory in a word learning task, and other cognitive and non-cognitive measures, such as perceptual sensitivity in visual search, reading speed, and rate of finger-tapping. On the basis of these results it was concluded that caffeine possesses cholinergic cognition enhancing properties. Caffeine could be used as a control drug in studies using the scopolamine paradigm and possibly also in other experimental studies of cognitive enhancers, as the effects of a newly developed cognition enhancing drug should at least be superior to the effects of three cups of coffee.
Aurtenetxe, Sara; García-Pacios, Javier; del Río, David; López, María E.; Pineda-Pardo, José A.; Marcos, Alberto; Delgado Losada, Maria L.; López-Frutos, José M.; Maestú, Fernando
Mild cognitive impairment (MCI) is considered a transitional stage between healthy aging and dementia, specifically Alzheimer's disease (AD). The most common cognitive impairment of MCI includes episodic memory loss and difficulties in working memory (WM). Interference can deplete WM, and an optimal WM performance requires an effective control of attentional resources between the memoranda and the incoming stimuli. Difficulties in handling interference lead to forgetting. However, the interplay between interference and WM in MCI is not well-understood and needs further investigation. The current study investigated the effect of interference during a WM task in 20 MCIs and 20 healthy elder volunteers. Participants performed a delayed match-to-sample paradigm which consisted in two interference conditions, distraction and interruption, and one control condition without any interference. Results evidenced a disproportionate impact of interference on the WM performance of MCIs, mainly in the presence of interruption. These findings demonstrate that interference, and more precisely interruption, is an important proxy for memory-related deficits in MCI. Thus, the current findings reveal novel evidence regarding the causes of WM forgetting in MCI patients, associated with difficulties in the mechanisms of attentional control. PMID:27790082
Aurtenetxe, Sara; García-Pacios, Javier; Del Río, David; López, María E; Pineda-Pardo, José A; Marcos, Alberto; Delgado Losada, Maria L; López-Frutos, José M; Maestú, Fernando
Mild cognitive impairment (MCI) is considered a transitional stage between healthy aging and dementia, specifically Alzheimer's disease (AD). The most common cognitive impairment of MCI includes episodic memory loss and difficulties in working memory (WM). Interference can deplete WM, and an optimal WM performance requires an effective control of attentional resources between the memoranda and the incoming stimuli. Difficulties in handling interference lead to forgetting. However, the interplay between interference and WM in MCI is not well-understood and needs further investigation. The current study investigated the effect of interference during a WM task in 20 MCIs and 20 healthy elder volunteers. Participants performed a delayed match-to-sample paradigm which consisted in two interference conditions, distraction and interruption, and one control condition without any interference. Results evidenced a disproportionate impact of interference on the WM performance of MCIs, mainly in the presence of interruption. These findings demonstrate that interference, and more precisely interruption, is an important proxy for memory-related deficits in MCI. Thus, the current findings reveal novel evidence regarding the causes of WM forgetting in MCI patients, associated with difficulties in the mechanisms of attentional control.
Cargin, J. Weaver; Maruff, P.; Collie, A.; Masters, C.
Mild memory impairment was detected in 28% of a sample of healthy community-dwelling older adults using the delayed recall trial of a word list learning task. Statistical analysis revealed that individuals with memory impairment also demonstrated relative deficits on other measures of memory, and tests of executive function, processing speed and…
Wener, Sarah E; Archibald, Lisa MD
This pilot study with an n-of-1 design examined whether children with a specific language impairment without working memory impairment (SLI), a specific working memory impairment without language impairment (SWMI), or mixed language and working memory impairments (L&WMI) may respond differently to treatment targeting verbal or visuospatial…
Ross, A P; Bartness, T J; Mielke, J G; Parent, M B
Over the past three decades there has been a substantial increase in the amount of fructose consumed by North Americans. Recent evidence from rodents indicates that hippocampal insulin signaling facilitates memory and excessive fructose consumption produces hippocampal insulin resistance. Based on this evidence, the present study tested the hypothesis that a high fructose diet would impair hippocampal-dependent memory. Adult male Sprague-Dawley rats (postnatal day 61) were fed either a control (0% fructose) or high fructose diet (60% of calories). Food intake and body mass were measured regularly. After 19 weeks, the rats were given 3 days of training (8 trials/day) in a spatial version of the water maze task, and retention performance was probed 48 h later. The high fructose diet did not affect acquisition of the task, but did impair performance on the retention test. Specifically, rats fed a high fructose diet displayed significantly longer latencies to reach the area where the platform had been located, made significantly fewer approaches to that area, and spent significantly less time in the target quadrant than did control diet rats. There was no difference in swim speed between the two groups. The retention deficits correlated significantly with fructose-induced elevations of plasma triglyceride concentrations. Consequently, the impaired spatial water maze retention performance seen with the high fructose diet may have been attributable, at least in part, to fructose-induced increases in plasma triglycerides.
Lebrun-Givois, C; Thomas-Antérion, C; Borg, C; Laurent, B
A case of episodic amnesia with impairment of time perception is described; it illustrates the link between time perception and autobiographical memory. This woman suffered from a Sheehan syndrome with anoxia at the age of 36 and since that date has had a strong and isolated difficulty to estimate the date and duration of events in a range of weeks, months or years. Conversely, short duration time spans are correctly evaluated. The patient's complaints also involve episodic memory. She reports many events from her biography very imprecisely while the semantic autobiographical data are preserved. The patient has difficulty in recalling the date of public events and the period of celebrity of well-known people. That observation confirms the specificity of time organization for long periods and the link with the episodic memory where the context of the dating task is crucial. The results are discussed in reference to autobiographical memory that involves mental wandering in time-space and the constitution of self over a time continuum.
Segobin, Shailendra; La Joie, Renaud; Ritz, Ludivine; Beaunieux, Hélène; Desgranges, Béatrice; Chételat, Gaël; Pitel, Anne Lise; Eustache, Francis
Measurement of synaptic activity by Positron Emission Tomography (PET) and its relation to cognitive functions such as episodic memory, working memory and executive functions in healthy humans and patients with neurocognitive disorders have been well documented. In this review, we introduce the concept of PET imaging that allows the observation of a particular biological process in vivo through the use of radio-labelled compounds, its general use to the medical world and its contributions to the understanding of memory systems. We then focus on [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG-PET), the radiotracer that is used to measure local cerebral metabolic rate of glucose that is indicative of synaptic activity in the brain. FDG-PET at rest has been at the forefront of functional neuroimaging over the past 3 decades, contributing to the understanding of cognitive functions in healthy humans and how these functional patterns change with cognitive alterations. We discuss methodological considerations that are important for optimizing FDG-PET imaging data prior to analysis. We then highlight the contribution of FDG-PET to the understanding of the patterns of functional differences in non-degenerative pathologies, normal ageing, and age-related neurodegenerative disorders. Through reasonable temporal and spatial resolution, its ability to measure synaptic activity in the whole brain, independently of any specific network and disease, makes it ideal to observe regional functional changes associated with memory impairment.
Bushman, Brad J; Bonacci, Angelica M
Participants watched a violent, sexually explicit, or neutral TV program that contained 9 ads. Participants recalled the advertised brands. They also identified the advertised brands from slides of supermarket shelves. The next day, participants were telephoned and asked to recall again the advertised brands. Results showed better memory for people who saw the ads during a neutral program than for people who saw the ads during a violent or sexual program both immediately after exposure and 24 hr later. Violence and sex impaired memory for males and females of all ages, regardless of whether they liked programs containing violence and sex. These results suggest that sponsoring violent and sexually explicit TV programs might not be a profitable venture for advertisers.
Zarrindast, M R; Haidari, H; Jafari, M R; Djahanguiri, B
Post-training administration of different doses of baclofen (a GABAB agonist) has been shown to impair memory retention, in a step-down passive avoidance test in mice. We have studied the effects of beta-adrenergic agonists and antagonists on baclofen-induced memory impairment in mice. Dobutamine (a beta 1-agonist) or salbutamol (a beta 2-agonist) reversed the memory impairment induced by baclofen without exhibiting intrinsic actions on memory when administered alone. The administration of atenolol (a beta 1-antagonist) or propranolol (a beta-antagonist) produced a memory impairment. When co-administered with baclofen, both atenolol and propranolol exacerbated the memory impairment induced by the GABAB agonist. It is concluded that beta-adrenergic mechanisms may be involved in the modulation of memory via GABAB receptors.
Hannula, Deborah E.; Tranel, Daniel; Allen, John S.; Kirchhoff, Brenda A.; Nickel, Allison E.; Cohen, Neal J.
Objective The objective of this study was to examine the dependence of item memory and relational memory on medial temporal lobe (MTL) structures. Patients with amnesia, who either had extensive MTL damage or damage that was relatively restricted to the hippocampus, were tested, as was a matched comparison group. Disproportionate relational memory impairments were predicted for both patient groups, and those with extensive MTL damage were also expected to have impaired item memory. Method Participants studied scenes, and were tested with interleaved two-alternative forced-choice probe trials. Probe trials were either presented immediately after the corresponding study trial (lag 1), five trials later (lag 5), or nine trials later (lag 9) and consisted of the studied scene along with a manipulated version of that scene in which one item was replaced with a different exemplar (item memory test) or was moved to a new location (relational memory test). Participants were to identify the exact match of the studied scene. Results As predicted, patients were disproportionately impaired on the test of relational memory. Item memory performance was marginally poorer among patients with extensive MTL damage, but both groups were impaired relative to matched comparison participants. Impaired performance was evident at all lags, including the shortest possible lag (lag 1). Conclusions The results are consistent with the proposed role of the hippocampus in relational memory binding and representation, even at short delays, and suggest that the hippocampus may also contribute to successful item memory when items are embedded in complex scenes. PMID:25068665
Broster, Lucas S.; Li, Juan; Smith, Charles D.; Jicha, Gregory A.; Schmitt, Frederick A.; Jiang, Yang
Study of repeated learning mechanisms has been limited in amnestic mild cognitive impairment, a preclinical stage of Alzheimer disease modifiable by cognitive rehabilitation. We assessed repeated contextual working memory decline as an indicator of amnestic mild cognitive impairment in a sample of 45 older adults recruited from the tertiary care setting. Results indicated that contextual working memory impairment distinguished adults with preclinical disease from those without impairment despite similar overall cognitive performance, and comparison of the indicator with standard-of-care neuropsychological measures indicated discriminant validity. Contextual working memory impairment may represent a novel predictor of Alzheimer disease conversion risk. PMID:24074205
Choi, Mi-Ran; Lee, Min Young; Hong, Ji Eun; Kim, Jeong Eun; Lee, Jae-Yong; Kim, Tae Hwan; Chun, Jang Woo; Shin, Hyun Kyung; Kim, Eun Ji
The present study investigated the effect of Rubus coreanus Miquel (RCM) on scopolamine-induced memory impairments in ICR mice. Mice were orally administrated RCM for 4 weeks and scopolamine was intraperitoneally injected into mice to induce memory impairment. RCM improved the scopolamine-induced memory impairment in mice. The increase of acetylcholinesterase activity caused by scopolamine was significantly attenuated by RCM treatment. RCM increased the levels of acetylcholine in the brain and serum of mice. The expression of choline acetyltransferase, phospho-cyclic AMP response element-binding protein, and phospho-extracellular signal-regulated kinase was significantly increased within the brain of mice treated with RCM. The brain antioxidant enzyme activity decreased by scopolamine was increased by RCM. These results demonstrate that RCM exerts a memory-enhancing effect via the improvement of cholinergic function and the potentiated antioxidant activity in memory-impaired mice. The results suggest that RCM may be a useful agent for improving memory impairment.
Tyurenkov, I N; Volotova, E V; Kurkin, D V
This work was aimed at evaluating the influence of gliatilin administration on the spatial memory in aged rats. Cognitive function and spatial memory in animals was evaluated using radial (8-beam) maze test. Errors of working spatial memory and reference memory were used as indicators of impaired cognitive function. It was found that aged (24-month) rats compared with younger (6-months) age group exhibited cognitive impairment, as manifested by deterioration of short- and long-term memory processes. Course administration of gliatilin in rats of the older age group at a dose of 100 mg/kg resulted in significant improvement of the working and reference spatial memory in aged rats.
Walrave, Laura; Vinken, Mathieu; Albertini, Giulia; De Bundel, Dimitri; Leybaert, Luc; Smolders, Ilse J.
Astrocytes are active players in higher brain function as they can release gliotransmitters, which are essential for synaptic plasticity. Various mechanisms have been proposed for gliotransmission, including vesicular mechanisms as well as non-vesicular ones, for example by passive diffusion via connexin hemichannels (HCs). We here investigated whether interfering with connexin43 (Cx43) HCs influenced hippocampal spatial memory. We made use of the peptide Gap19 that blocks HCs but not gap junction channels and is specific for Cx43. To this end, we microinfused transactivator of transcription linked Gap19 (TAT-Gap19) into the brain ventricle of male NMRI mice and assessed spatial memory in a Y maze. We found that the in vivo blockade of Cx43 HCs did not affect the locomotor activity or spatial working memory in a spontaneous alternation Y maze task. Cx43 blockade did however significantly impair the spatial short-term memory in a delayed spontaneous alternation Y maze task. These results indicate that Cx43 HCs play a role in spatial short-term memory. PMID:28066184
Joubert, Sven; Brambati, Simona M.; Ansado, Jennyfer; Barbeau, Emmanuel J.; Felician, Olivier; Didic, Mira; Lacombe, Jacinthe; Goldstein, Rachel; Chayer, Celine; Kergoat, Marie-Jeanne
Semantic deficits in Alzheimer's disease have been widely documented, but little is known about the integrity of semantic memory in the prodromal stage of the illness. The aims of the present study were to: (i) investigate naming abilities and semantic memory in amnestic mild cognitive impairment (aMCI), early Alzheimer's disease (AD) compared to…
Allé, Mélissa C; Manning, Liliann; Potheegadoo, Jevita; Coutelle, Romain; Danion, Jean-Marie; Berna, Fabrice
Autobiographical memory, central in human cognition and every day functioning, enables past experienced events to be remembered. A variety of disorders affecting autobiographical memory are characterized by the difficulty of retrieving specific detailed memories of past personal events. Owing to the impact of autobiographical memory impairment on patients' daily life, it is necessary to better understand these deficits and develop relevant methods to improve autobiographical memory. The primary objective of the present systematic PRISMA review was to give an overview of the first empirical evidence of the potential of wearable cameras in autobiographical memory investigation in remediating autobiographical memory impairments. The peer-reviewed literature published since 2004 on the usefulness of wearable cameras in research protocols was explored in 3 databases (PUBMED, PsycINFO, and Google Scholar). Twenty-eight published studies that used a protocol involving wearable camera, either to explore wearable camera functioning and impact on daily life, or to investigate autobiographical memory processing or remediate autobiographical memory impairment, were included. This review analyzed the potential of wearable cameras for 1) investigating autobiographical memory processes in healthy volunteers without memory impairment and in clinical populations, and 2) remediating autobiographical memory in patients with various kinds of memory disorder. Mechanisms to account for the efficacy of wearable cameras are also discussed. The review concludes by discussing certain limitations inherent to using cameras, and new research perspectives. Finally, ethical issues raised by this new technology are considered.
Edwards, Rachel; Ungar, Simon; Blades, Mark
This study evaluated descriptions, either from memory or by using a map (print or tactile), of 12 visually impaired and 12 sighted elementary grade children of two routes around their schools. Descriptions from maps were generally poorer than those from memory. Qualitative differences were also found between descriptions of visually impaired and…
Rindal, Eric J; DeFranco, Rachel M; Rich, Patrick R; Zaragoza, Maria S
In a recent PNAS article, Chan and LaPaglia (2013) provided arguments and evidence to support the claim that reactivating a witnessed memory (by taking a test) renders the memory labile and susceptible to impairment by subsequent misinformation. In the current article, we argue that Chan and LaPaglia’s (2013) findings are open to alternative interpretations, and further test the hypothesis that reactivation increases a witnessed memory’s susceptibility to impairment. To this end, the current studies used a different set of materials and a different measure of memory impairment, the Modified Recognition Test (McCloskey & Zaragoza, 1985). In Experiment 1a, we established that our reactivation manipulation was effective by showing that we could replicate the well-established retrieval enhanced suggestibility effect with our materials. However, when we assessed potential impairment of the witnessed memory with the Modified Recognition Test (Experiments 1a and 1b), we failed to find evidence that reactivating the witnessed memory prior to misinformation impaired memory for the originally witnessed event. In Experiment 2, we replicated Chan and LaPaglia’s (2013) findings when we used their memory impairment measure (misinformation-free True/False Recognition Test) and showed why that test does not permit clear inferences about memory impairment. Collectively, the results showed that, although the reactivation manipulation increased susceptibility to suggestion (i.e., as evidenced by increased reporting of suggested misinformation), there was no evidence that reactivation through testing increased the original memory’s susceptibility to impairment.
Mitolo, Micaela; Gardini, Simona; Fasano, Fabrizio; Crisi, Girolamo; Pelosi, Annalisa; Pazzaglia, Francesca; Caffarra, Paolo
Spatial abilities decline in normal aging and decrease faster and earlier in Alzheimer's disease (AD), but these deficits are under investigated. The main goals of this study were to assess visuospatial memory abilities in mild cognitive impairment (MCI), in order to verify whether these tasks might be valid as the standard cognitive test to differentiate MCI individuals from normal controls and to investigate the brain structural correlates of visuospatial deficits. Twenty MCI patients and fourteen healthy elderly controls underwent an experimental visuospatial battery, which also included self-rating spatial questionnaires, and structural MRI brain imaging. Compared to healthy elderly controls, MCI patients scored significantly worse in almost all visuospatial tasks. ROC analysis showed that visuospatial tasks had an elevated discriminant power between groups (AUC >0.90). Voxel-based morphometry analysis, compared to controls, disclosed a higher level of atrophy in frontal and medio-temporal regions and a different pattern of correlation between grey matter values and visuospatial performance, with wider distributed areas of the occipital and middle temporal cortex in the map and route learning. This study indicates that visuospatial memory tests are valid tools in completing the diagnostic evaluation of MCI.
Wang, Wei; Tan, Tao; Tu, Man; He, Wenting; Dong, Zhifang; Han, Huili
Reports of the effects of pentobarbital on learning and memory are contradictory. Some studies have not shown any interference with learning and memory, whereas others have shown that pentobarbital impairs memory and that these impairments can last for long periods. However, it is unclear whether acute local microinjections of pentobarbital affect learning and memory, and if so, the potential mechanisms are also unclear. Here, we reported that the intra-hippocampal infusion of pentobarbital (8.0mM, 1μl per side) significantly impaired hippocampus-dependent spatial learning and memory retrieval. Moreover, in vitro electrophysiological recordings revealed that these behavioral changes were accompanied by impaired hippocampal CA1 long-term potentiation (LTP) and suppressed neuronal excitability as reflected by a decrease in the number of action potentials (APs). These results suggest that acute pentobarbital application causes spatial learning and memory deficits that might be attributable to the suppression of synaptic plasticity and neuronal excitability.
Atsak, Piray; Guenzel, Friederike M; Kantar-Gok, Deniz; Zalachoras, Ioannis; Yargicoglu, Piraye; Meijer, Onno C; Quirarte, Gina L; Wolf, Oliver T; Schwabe, Lars; Roozendaal, Benno
Acute stress and elevated glucocorticoid hormone levels are well known to impair the retrieval of hippocampus-dependent 'declarative' memory. Recent findings suggest that stress might also impair the retrieval of non-hippocampal memories. In particular, stress shortly before retention testing was shown to impair the retrieval of striatal stimulus-response associations in humans. However, the mechanism underlying this stress-induced retrieval impairment of non-hippocampal stimulus-response memory remains elusive. In the present study, we investigated whether an acute elevation in glucocorticoid levels mediates the impairing effects of stress on retrieval of stimulus-response memory. Male Sprague-Dawley rats were trained on a stimulus-response task in an eight-arm radial maze until they learned to associate a stimulus, i.e., cue, with a food reward in one of the arms. Twenty-four hours after successful acquisition, they received a systemic injection of vehicle, corticosterone (1mg/kg), the corticosterone-synthesis inhibitor metyrapone (35mg/kg) or were left untreated 1h before retention testing. We found that the corticosterone injection impaired the retrieval of stimulus-response memory. We further found that the systemic injection procedure per se was stressful as the vehicle administration also increased plasma corticosterone levels and impaired the retrieval of stimulus-response memory. However, memory retrieval was not impaired when rats were tested 2min after the systemic vehicle injection, before any stress-induced elevation in corticosterone levels had occurred. Moreover, metyrapone treatment blocked the effect of injection stress on both plasma corticosterone levels and memory retrieval impairment, indicating that the endogenous corticosterone response mediates the stress-induced memory retrieval impairment. None of the treatments affected rats' locomotor activity or motivation to search for the food reward within the maze. These findings show that stress
Monsey, Melissa S; Gerhard, Danielle M; Boyle, Lara M; Briones, Miguel A; Seligsohn, Ma'ayan; Schafe, Glenn E
Curcumin, a yellow-pigment compound found in the popular Indian spice turmeric (Curcuma longa), has been extensively investigated for its anti-inflammatory, chemopreventative, and antidepressant properties. Here, we examined the efficacy of dietary curcumin at impairing the consolidation and reconsolidation of a Pavlovian fear memory, a widely studied animal model of traumatic memory formation in posttraumatic stress disorder (PTSD). We show that a diet enriched with 1.5% curcumin prevents the training-related elevation in the expression of the immediate early genes (IEGs) Arc/Arg3.1 and Egr-1 in the lateral amygdala (LA) and impairs the ‘consolidation' of an auditory Pavlovian fear memory; short-term memory (STM) is intact, whereas long-term memory (LTM) is significantly impaired. Next, we show that dietary curcumin impairs the ‘reconsolidation' of a recently formed auditory Pavlovian fear memory; fear memory retrieval (reactivation) and postreactivation (PR)-STM are intact, whereas PR-LTM is significantly impaired. Additional experiments revealed that dietary curcumin is also effective at impairing the reconsolidation of an older, well-consolidated fear memory. Furthermore, we observed that fear memories that fail to reconsolidate under the influence of dietary curcumin are impaired in an enduring manner; unlike extinguished fear memories, they are not subject to reinstatement or renewal. Collectively, our findings indicate that a diet enriched with curcumin is capable of impairing fear memory consolidation and reconsolidation processes, findings that may have important clinical implications for the treatment of disorders such as PTSD that are characterized by unusually strong and persistently reactivated fear memories. PMID:25430781
Schuchardt, Kirsten; Bockmann, Ann-Katrin; Bornemann, Galina; Maehler, Claudia
Purpose: On the basis of Baddeley's working memory model (1986), we examined working memory functioning in children with learning disorders with and without specific language impairment (SLI). We pursued the question whether children with learning disorders exhibit similar working memory deficits as children with additional SLI. Method: In…
Wardlaw, Sarah M.; Phan, Trongha X.; Saraf, Amit; Chen, Xuanmao; Storm, Daniel R.
Perturbing the circadian system by electrolytically lesioning the suprachiasmatic nucleus (SCN) or varying the environmental light:dark schedule impairs memory, suggesting that memory depends on the circadian system. We used a genetic approach to evaluate the role of the molecular clock in memory. Bmal1[superscript -/-] mice, which are arrhythmic…
Canal, Clinton E.; Chang, Qing; Gold, Paul E.
Infusions of CREB antisense into the amygdala prior to training impair memory for aversive tasks, suggesting that the antisense may interfere with CRE-mediated gene transcription and protein synthesis important for the formation of new memories within the amygdala. However, the amygdala also appears to modulate memory formation in distributed…
Lange, Rael T; Chelune, Gordon J
The purpose of this study was to extend previous research by Lange and Chelune (2006) by evaluating the clinical utility of GAI-memory discrepancy scores to detect memory impairment using estimated premorbid GAI scores (i.e., GAI-E) rather than obtained GAI scores. Participants were 34 patients with Alzheimer's-type dementia and a sub-sample of 34 demographically matched participants from the WAIS-III/WMS-III standardization sample. GAI-memory discrepancy scores were more effective at differentiating Alzheimer's patients versus healthy controls when using estimated premorbid GAI scores than obtained GAI scores. However, GAI(E)-memory discrepancy scores failed to provide unique interpretive information beyond that which is gained from interpretation of the memory index scores alone. This was most likely due to the prevalence of obvious memory impairment in this patient population. Future research directions are discussed.
Chen, Yen-Ting; Pinto Neto, Osmar; de Miranda Marzullo, Ana Carolina; Kennedy, Deanna M; Fox, Emily J; Christou, Evangelos A
The purpose of this study was to determine whether older adults compared with young adults exhibit impaired end-point accuracy during a two-finger task due to altered activation of the contributing synergistic muscles. Nine young (21.3 years ± 1.6 years, 4 men) and 9 older (73.1 years ± 6.4 years, 5 men) were instructed to accurately match the center of a target with concurrent abduction of the index and little fingers (synergistic two-finger task). The target comprised of 20% MVC and 200 ms. Visual feedback of the force trajectory and target was provided 1s after each trial. Subjects completed 40 trials and the last 10 were used for analysis. Endpoint accuracy was quantified as the normalized deviation from the target in terms of peak force (peak force error), time-to-peak force (time-to-peak force error), and a combination of the two (overall error). Motor output variability was quantified as the standard deviation and coefficient of variation (CV) of peak force and time to peak force. The neural activation of the involved synergist muscles (first dorsal interosseus (FDI) and abductor digiti minimi (ADM)) was quantified with the electromyography (EMG) amplitude (root mean square) and its frequency structure (wavelet analysis). Older adults exhibited significantly greater peak force (46.7 ± 10% vs. 24.9 ± 3.2%) and overall endpoint error (68.5 ± 9.7% vs. 41.7 ± 4.3%), whereas the time to peak force error was similar for the two age groups. Older adults also exerted greater peak force variability than young adults, as quantified by the CV of peak force (34.3 ± 3.5% vs. 24.1 ± 2.3%). The greater peak force error in older adults was associated with changes in the activation of the ADM muscle but not the FDI. Specifically, greater peak force error was associated with greater power from 13-30 Hz and lesser power from 30-60 Hz. These results, therefore, suggest that older adults compared with young adults exhibit impaired endpoint force accuracy during a two
Rabinowitz, Akiva; Cohen, Sarah J; Finn, Deborah A; Stackman, Robert W
Allopregnanolone (ALLO, or 3α-hydroxy-5α-pregnan-20-one) is a steroid metabolite of progesterone and a potent endogenous positive allosteric modulator of GABA-A receptors. Systemic ALLO has been reported to impair spatial, but not nonspatial learning in the Morris water maze (MWM) and contextual memory in rodents. These cognitive effects suggest an influence of ALLO on hippocampal-dependent memory, although the specific nature of the neurosteroid's effects on learning, memory or performance is unclear. The present studies aimed to determine: (i) the memory process(es) affected by systemic ALLO using a nonspatial object memory task; and (ii) whether ALLO affects object memory via an influence within the dorsal hippocampus. Male C57BL/6J mice received systemic ALLO either before or immediately after the sample session of a novel object recognition (NOR) task. Results demonstrated that systemic ALLO impaired the encoding and consolidation of object memory. A subsequent study revealed that bilateral microinfusion of ALLO into the CA1 region of dorsal hippocampus immediately following the NOR sample session also impaired object memory consolidation. In light of debate over the hippocampal-dependence of object recognition memory, we also tested systemic ALLO-treated mice on a contextual and cued fear-conditioning task. Systemic ALLO impaired the encoding of contextual memory when administered prior to the context pre-exposure session. Together, these results indicate that ALLO exhibits primary effects on memory encoding and consolidation, and extend previous findings by demonstrating a sensitivity of nonspatial memory to ALLO, likely by disrupting dorsal hippocampal function.
Banks, Jonathan B; Tartar, Jaime L; Tamayo, Brittney A
A large and growing body of research demonstrates the impact of psychological stress on working memory. However, the typical study approach tests the effects of a single biological or psychological factor on changes in working memory. The current study attempted to move beyond the standard single-factor assessment by examining the impact of 2 possible factors in stress-related working memory impairments. To this end, 60 participants completed a working memory task before and after either a psychological stressor writing task or a control writing task and completed measures of both cortisol and mind wandering. We also included a measure of state anxiety to examine the direct and indirect effect on working memory. We found that mind wandering mediated the relationship between state anxiety and working memory at the baseline measurement. This indirect relationship was moderated by cortisol, such that the impact of mind wandering on working memory increased as cortisol levels increased. No overall working memory impairment was observed following the stress manipulation, but increases in state anxiety and mind wandering were observed. State anxiety and mind wandering independently mediated the relationship between change in working memory and threat perception. The indirect paths resulted in opposing effects on working memory. Combined, the findings from this study suggest that cortisol enhances the impact of mind wandering on working memory, that state anxiety may not always result in stress-related working memory impairments, and that high working memory performance can protect against mind wandering.
Raio, Candace M.; Brignoni-Perez, Edith; Goldman, Rachel; Phelps, Elizabeth A.
Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays an important role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent research in rodents found that exposure to stress led to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress responses, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, one day later participants in the stress group (n = 27) demonstrated significantly less
Alescio-Lautier, B.; Michel, B. F.; Herrera, C.; Elahmadi, A.; Chambon, C.; Touzet, C.; Paban, V.
It has been proposed that visual recognition memory and certain attentional mechanisms are impaired early in Alzheimer disease (AD). Little is known about visuospatial recognition memory in AD. The crucial role of the hippocampus on spatial memory and its damage in AD suggest that visuospatial recognition memory may also be impaired early. The aim…
Weinand, Martin E.; Labiner, David M.; Ahern, Geoffrey L.
Memory function during the intracarotid amobarbital test was studied to test the hypothesis that left hemisphere memory impairment is associated with sensory auras. In a series of 37 patients undergoing preoperative evaluation for epilepsy surgery, the quantitative memory scores during amobarbital inactivation of right and left hemisphere were analyzed for correlation with habitual epileptic auras classified as either (a) experiential, forced emotion, or whole-body dysphoria or (b) sensory hallucinations and/or illusions or localized dysesthesias. The left hemispheric memory score impairment was significantly worse in association with auras classified as sensory hallucinations and/or illusions or localized dysesthesias compared with auras classified as experiential, forced emotion, or whole-body dysphoria (P < 0.05). This finding may assist in predicting left-sided hemispheric memory dysfunction in patients with seizures beginning as auras involving sensory material. The results suggest an integration of perceptual and mnemonic dysfunction in which sensory auras are associated with left hemispheric memory impairment.
van Wel, J H P; Kuypers, K P C; Theunissen, E L; Bosker, W M; Bakker, K; Ramaekers, J G
3,4-Methylenedioxymethamphetamine (MDMA) or ‘ecstasy' has been associated with memory deficits during abstinence and intoxication. The human neuropharmacology of MDMA-induced memory impairment is unknown. This study investigated the role of 5-HT2A and 5-HT1A receptors in MDMA-induced memory impairment. Ketanserin is a 5-HT2A receptor blocker and pindolol a 5-HT1A receptor blocker. It was hypothesized that pretreatment with ketanserin and pindolol would protect against MDMA-induced memory impairment. Subjects (N=17) participated in a double-blind, placebo-controlled, within-subject design involving six experimental conditions consisting of pretreatment (T1) and treatment (T2). T1 preceded T2 by 30 min. T1–T2 combinations were: placebo–placebo, pindolol 20 mg–placebo, ketanserin 50 mg–placebo, placebo–MDMA 75 mg, pindolol 20 mg–MDMA 75 mg, and ketanserin 50 mg–MDMA 75 mg. Memory function was assessed at Tmax of MDMA by means of a word-learning task (WLT), a spatial memory task and a prospective memory task. MDMA significantly impaired performance in all memory tasks. Pretreatment with a 5-HT2A receptor blocker selectively interacted with subsequent MDMA treatment and prevented MDMA-induced impairment in the WLT, but not in the spatial and prospective memory task. Pretreatment with a 5-HT1A blocker did not affect MDMA-induced memory impairment in any of the tasks. Together, the results demonstrate that MDMA-induced impairment of verbal memory as measured in the WLT is mediated by 5-HT2A receptor stimulation. PMID:21562484
Maylor, E A
Subjects over the age of 50 listened to theme tunes of remote, recent, and frequent television programs. If they recognized the tune, they were asked for the name of the program and for as much information about the program as possible. From the responses to a subsequent questionnaire, it was possible to divide the data according to whether or not the subjects watched the programs. There was no effect of age on the recognition and naming of programs subjects never watched. For programs they watched (a true test of memory), older subjects recognized fewer tunes as familiar and were less able than younger subjects to name the programs with familiar tunes. Neither the amount of exposure nor the delay since exposure had a significant influence on the recognition and naming impairments with age. Older subjects reported less information about programs they watched than younger subjects. In multiple regression analyses, age was a better predictor of performance than measures of current cognitive ability. The results are compared with the effects of age on the recognition and naming of famous faces (Maylor, 1990a). It is argued that the studies together support the view that the information processing rate decreases with age; therefore the elderly are poor at speeded tasks, the most dramatic effects appearing for later components of sequential processes.
Mapstone, Mark; Cheema, Amrita K; Fiandaca, Massimo S; Zhong, Xiaogang; Mhyre, Timothy R; MacArthur, Linda H; Hall, William J; Fisher, Susan G; Peterson, Derick R; Haley, James M; Nazar, Michael D; Rich, Steven A; Berlau, Dan J; Peltz, Carrie B; Tan, Ming T; Kawas, Claudia H; Federoff, Howard J
Alzheimer’s disease causes a progressive dementia that currently affects over 35 million individuals worldwide and is expected to affect 115 million by 2050 (ref. 1). There are no cures or disease-modifying therapies, and this may be due to our inability to detect the disease before it has progressed to produce evident memory loss and functional decline. Biomarkers of preclinical disease will be critical to the development of disease-modifying or even preventative therapies2. Unfortunately, current biomarkers for early disease, including cerebrospinal fluid tau and amyloid-β levels3, structural and functional magnetic resonance imaging4 and the recent use of brain amyloid imaging5 or inflammaging6, are limited because they are either invasive, time-consuming or expensive. Blood-based biomarkers may be a more attractive option, but none can currently detect preclinical Alzheimer’s disease with the required sensitivity and specificity7. Herein, we describe our lipidomic approach to detecting preclinical Alzheimer’s disease in a group of cognitively normal older adults. We discovered and validated a set of ten lipids from peripheral blood that predicted phenoconversion to either amnestic mild cognitive impairment or Alzheimer’s disease within a 2–3 year timeframe with over 90% accuracy. This biomarker panel, reflecting cell membrane integrity, may be sensitive to early neurodegeneration of preclinical Alzheimer’s disease. PMID:24608097
Schwabe, Lars; Wolf, Oliver T
Stress before retention testing impairs memory, whereas memory performance is enhanced when the learning context is reinstated at retrieval. In the present study, we examined whether the negative impact of stress before memory retrieval can be attenuated when memory is tested in the same environmental context as that in which learning took place. Subjects learned a 2-D object location task in a room scented with vanilla. Twenty-four hours later, they were exposed to stress or a control condition before memory for the object location task was assessed in a cued-recall test, either in the learning context or in a different context (unfamiliar room without the odor). Stress impaired memory when assessed in the unfamiliar context, but not when assessed in the learning context. These results suggest that the detrimental effects of stress on memory retrieval can be abolished when a distinct learning context is reinstated at test.
Mattfeld, Aaron T; Whitfield-Gabrieli, Susan; Biederman, Joseph; Spencer, Thomas; Brown, Ariel; Fried, Ronna; Gabrieli, John D E
Prevailing neuropsychological models of attention-deficit/hyperactivity disorder (ADHD) propose that ADHD arises from deficits in executive functions such as working memory, but accumulating clinical evidence suggests a dissociation between ADHD and executive dysfunctions. This study examined whether ADHD and working memory capacity are behaviorally and neurobiologically separable using functional magnetic resonance imaging (fMRI). Participants diagnosed with ADHD in childhood who subsequently remitted or persisted in their diagnosis as adults were characterized at follow-up in adulthood as either impaired or unimpaired in spatial working memory relative to controls who never had ADHD. ADHD participants with impaired spatial working memory performed worse than controls and ADHD participants with unimpaired working memory during an n-back working memory task while being scanned. Both controls and ADHD participants with unimpaired working memory exhibited significant linearly increasing activation in the inferior frontal junction, precuneus, lingual gyrus, and cerebellum as a function of working-memory load, and these activations did not differ significantly between these groups. ADHD participants with impaired working memory exhibited significant hypoactivation in the same regions, which was significantly different than both control participants and ADHD participants with unimpaired working memory. These findings support both a behavioral and neurobiological dissociation between ADHD and working memory capacity.
Mizoguchi, Hiroyuki; Ibi, Daisuke; Takase, Fumiaki; Nagai, Taku; Kamei, Hiroyuki; Toth, Erika; Sato, Jun; Takuma, Kazuhiro; Yamada, Kiyofumi
Nicotine is hypothesized to have therapeutic effects on attentional and cognitive abnormalities in psychosis. In this study, we investigated the effect of nicotine on impaired spatial working memory in repeated methamphetamine (METH)-treated rats. Rats were administered METH (4 mg/kg, s.c.) once a day for 7 days, and their working memory was assessed with a delayed spatial win-shift task in a radial arm maze. The task consisted of two phases, a training phase and a test phase, separated by a delay. Control animals showed impaired performance in the test phase when the delay time was increased to 120 min or longer, while METH-treated rats showed impaired performance with a shorter delay time of 90 min. Memory impairment in METH-treated rats persisted for at least 14 days after drug withdrawal. METH-induced impairment of working memory was reversed by nicotine (0.3mg/kg, p.o., for 7 days), but the effect was diminished 7 days after the withdrawal. In control rats, nicotine decreased the number of working memory errors in the test with delay time of 120 min when administered before the training phase. Neither post-training nor pre-test administration of nicotine had any effect on working memory. These findings suggest that nicotine may have some protective effect against the impairment of working memory.
Szucs, Denes; Devine, Amy; Soltesz, Fruzsina; Nobes, Alison; Gabriel, Florence
Developmental dyscalculia is thought to be a specific impairment of mathematics ability. Currently dominant cognitive neuroscience theories of developmental dyscalculia suggest that it originates from the impairment of the magnitude representation of the human brain, residing in the intraparietal sulcus, or from impaired connections between number symbols and the magnitude representation. However, behavioral research offers several alternative theories for developmental dyscalculia and neuro-imaging also suggests that impairments in developmental dyscalculia may be linked to disruptions of other functions of the intraparietal sulcus than the magnitude representation. Strikingly, the magnitude representation theory has never been explicitly contrasted with a range of alternatives in a systematic fashion. Here we have filled this gap by directly contrasting five alternative theories (magnitude representation, working memory, inhibition, attention and spatial processing) of developmental dyscalculia in 9-10-year-old primary school children. Participants were selected from a pool of 1004 children and took part in 16 tests and nine experiments. The dominant features of developmental dyscalculia are visuo-spatial working memory, visuo-spatial short-term memory and inhibitory function (interference suppression) impairment. We hypothesize that inhibition impairment is related to the disruption of central executive memory function. Potential problems of visuo-spatial processing and attentional function in developmental dyscalculia probably depend on short-term memory/working memory and inhibition impairments. The magnitude representation theory of developmental dyscalculia was not supported.
Ahmadian-Attar, Mohammad Mahdi; Ahmadiani, Abolhassan; Kamalinejad, Mohammad; Dargahi, Leila; Mosaddegh, Mahmoud
Iranian Traditional Medicine (ITM) describes a kind of dementia with similar signs and symptoms of Alzheimer's disease (AD). It explains the pathology of dementia with cold intemperament of the brain, which means that the brain is colder than its healthy form. ITM strategy for treatment of dementia is to heat the brain up by medical "hot" herbs. Nepeta menthoides (NM) is one of these "hot" herbs. To evaluate the veracity of ITM concept about dementia and its treatment, we first try to examine if coldness of brain can make memory impairment. If so, can NM reverse memory impairment? Rats in cold-water-induced hypothermic (CWH) groups were immersed up to the neck in 3.5 °C water, for 5 min during 14 consecutive days. As a control, rats were forced to swim in warm water at the same conditions. To eliminate the impact of forced swimming stress, a group of intact rats was also added. After last swimming in day 14, some groups received drug (100 or 500 mg/ Kg aqueous extract of NM) or vehicle via i.p. injection. Learning and memory were assessed by Morris water maze, and tau hyperphosphorylation was measured by western blotting. The results showed that CWH impairs learning and memory and induces tau hyperphosphorylation. 100 mg/Kg of NM reversed memory impairment as well as tau hyperphosphorylation. ITM theory about the relationship between brain hypothermia and dementia is in accordance with our findings.
Malstädt, Nadine; Hasselhorn, Marcus; Lehmann, Martin
This study examined supraspan free recall in children with and without spelling impairment. A repeated free recall task involving overt rehearsal and three computer-based adaptive working memory tasks were administered to 54 eight-year-old children. Children without spelling impairments tended to recall more items than did those children with spelling deficits. Video analyses revealed that recall behaviour was similar in impaired and unimpaired children, indicating that both groups applied similar learning activities. Group differences in number of recalled items were attributed to differences in working memory subcapacities between children with and without spelling impairment, especially with regard to central executive and phonological loop functioning.
McEntee, William J.; Mair, Robert G.
The concentration of the primary brain metabolite of norepinephrine is diminished in the lumbar spinal fluid of patients with Korsakoff's syndrome. The extent of its reduction is correlated with measures of memory impairment. (BB)
Gillam, Ronald B.
This book contains articles from two issues of "Topics in Language Disorders" that focus on recent developments in the understanding of short-term memory, working memory, and long-term memory systems and their relationship to language comprehension, lexical development, early academic development, later academic development, and communication…
van Daal, John; Verhoeven, Ludo; van Leeuwe, Jan; van Balkom, Hans
In the present study, the relations of various aspects of working memory to various aspects of language problems in a clinical sample of 97 Dutch speaking 5-year-old children with severe language problems were studied. The working memory and language abilities of the children were examined using an extensive battery of tests. Working memory was…
Raio, Candace M; Brignoni-Perez, Edith; Goldman, Rachel; Phelps, Elizabeth A
Extinction training is a form of inhibitory learning that allows an organism to associate a previously aversive cue with a new, safe outcome. Extinction does not erase a fear association, but instead creates a competing association that may or may not be retrieved when a cue is subsequently encountered. Characterizing the conditions under which extinction learning is expressed is important to enhancing the treatment of anxiety disorders that rely on extinction-based exposure therapy as a primary treatment technique. The ventromedial prefrontal cortex, which plays a critical role in the expression of extinction memory, has been shown to be functionally impaired after stress exposure. Further, recent work in rodents has demonstrated that exposure to stress leads to deficits in extinction retrieval, although this has yet to be tested in humans. To explore how stress might influence extinction retrieval in humans, participants underwent a differential aversive learning paradigm, in which one image was probabilistically paired with an aversive shock while the other image denoted safety. Extinction training directly followed, at which point reinforcement was omitted. A day later, participants returned to the lab and either completed an acute stress manipulation (i.e., cold pressor), or a control task, before undergoing an extinction retrieval test. Skin conductance responses and salivary cortisol concentrations were measured throughout each session as indices of fear arousal and neuroendocrine stress response, respectively. The efficacy of our stress induction was established by observing significant increases in cortisol for the stress condition only. We examined extinction retrieval by comparing conditioned responses during the last trial of extinction (day 1) with that of the first trial of re-extinction (day 2). Groups did not differ on initial fear acquisition or extinction, however, a day later participants in the stress group (n=27) demonstrated significantly
Busquets-Garcia, Arnau; Gomis-González, Maria; Srivastava, Raj Kamal; Cutando, Laura; Ortega-Alvaro, Antonio; Ruehle, Sabine; Remmers, Floortje; Bindila, Laura; Bellocchio, Luigi; Marsicano, Giovanni; Lutz, Beat; Maldonado, Rafael
Stressful events can generate emotional memories linked to the traumatic incident, but they also can impair the formation of nonemotional memories. Although the impact of stress on emotional memories is well studied, much less is known about the influence of the emotional state on the formation of nonemotional memories. We used the novel object-recognition task as a model of nonemotional memory in mice to investigate the underlying mechanism of the deleterious effect of stress on memory consolidation. Systemic, hippocampal, and peripheral blockade of cannabinoid type-1 (CB1) receptors abolished the stress-induced memory impairment. Genetic deletion and rescue of CB1 receptors in specific cell types revealed that the CB1 receptor population specifically in dopamine β-hydroxylase (DBH)-expressing cells is both necessary and sufficient for stress-induced impairment of memory consolidation, but CB1 receptors present in other neuronal populations are not involved. Strikingly, pharmacological manipulations in mice expressing CB1 receptors exclusively in DBH+ cells revealed that both hippocampal and peripheral receptors mediate the impact of stress on memory consolidation. Thus, CB1 receptors on adrenergic and noradrenergic cells provide previously unrecognized cross-talk between central and peripheral mechanisms in the stress-dependent regulation of nonemotional memory consolidation, suggesting new potential avenues for the treatment of cognitive aspects on stress-related disorders. PMID:27528659
article we demonstrate how a modality-specific semantic memory system can account for category- specific impairments after brain damage. Specifically...different sensorimotor channels. In this article we demonstrate how a modality-specific semantic memory system can account for category-specific...just one modality (e.g. visual or auditory agnosia ) or impaired manipulation of objects with specific uses, despite intact recognition of them (apraxia
West, Robert; McNerney, M Windy; Krauss, Iseli
In this study we examine the locus of a prospective memory deficit in an individual with multiple sclerosis. Extensive psychometric and neuropsychological testing revealed above average to superior general intelligence, retrospective and autobiographical memory, short-term/working memory and executive functions. In contrast, the individual demonstrated poor prospective memory on a variety of measures incorporating naturalistic, self-report, and laboratory methods. This deficit appeared to arise from a disruption of processes underlying strategic monitoring. These data clearly demonstrate that impaired prospective memory can exist in the presence of an otherwise intact neuropsychological profile.
Volkers, K. M.; Scherder, E. J. A.
Background. Physical performances and cognition are positively related in cognitively healthy people. The aim of this study was to examine whether physical performances are related to specific cognitive functioning in older people with mild to severe cognitive impairment. Methods. This cross-sectional study included 134 people with a mild to severe cognitive impairment (mean age 82 years). Multiple linear regression was performed, after controlling for covariates and the level of global cognition, with the performances on mobility, strength, aerobic fitness, and balance as predictors and working memory and episodic memory as dependent variables. Results. The full models explain 49–57% of the variance in working memory and 40–43% of episodic memory. Strength, aerobic fitness, and balance are significantly associated with working memory, explaining 3–7% of its variance, irrespective of the severity of the cognitive impairment. Physical performance is not related to episodic memory in older people with mild to severe cognitive impairment. Conclusions. Physical performance is associated with working memory in older people with cognitive impairment. Future studies should investigate whether physical exercise for increased physical performance can improve cognitive functioning. This trial is registered with ClinicalTrials.gov NTR1482. PMID:24757674
Dodwell, Kristy; Bavin, Edith L.
Background: Narratives have been used by a number of researchers to investigate the language of children with specific language impairment (SLI). While a number of explanations for SLI have been proposed, there is now mounting evidence that children with SLI have limited memory resources. Phonological memory has been the focus of the research on…
Rindal, Eric J.; DeFranco, Rachel M.; Rich, Patrick R.; Zaragoza, Maria S.
In a recent PNAS article, Chan and LaPaglia (2013) provided arguments and evidence to support the claim that reactivating a witnessed memory (by taking a test) renders the memory labile and susceptible to impairment by subsequent misinformation. In the current article, we argue that Chan and LaPaglia's (2013) findings are open to alternative…
Spanoudis, George C.; Natsopoulos, Demetrios
Memory and language operate in synergy. Recent literature stresses the importance of memory functioning in interpreting language deficits. Two groups of 50 children each, ages 8-12 were studied. The first group included children with specific language impairment, while the participants in the second group were typically developing children. The…
Nadel, Lynn; Uecker, Anne
Thirty Native American children (mean age=10.3 years), 15 identified with fetal alcohol syndrome (FAS) and 15 controls, were asked to recall places and objects in a task previously shown to be sensitive to memory skills in individuals with and without mental retardation. Children with FAS demonstrated a spatial but not an object memory impairment.…
Lee, Tatia M. C.; Au, Ricky K. C.; Liu, Ho-Ling; Ting, K. H.; Huang, Chih-Mao; Chan, Chetwyn C. H.
Previous neuroimaging studies have suggested that the neural activity associated with truthful recall, with false memory, and with feigned memory impairment are different from one another. Here, we report a functional magnetic resonance imaging (fMRI) study that addressed an important but yet unanswered question: Is the neural activity associated…
Tranel, Daniel; Adolphs, Ralph; Buchanan, Tony W.
Stress can enhance or impair memory performance. Both cortisol release and sympathetic nervous system responses have been implicated in these differential effects. Here we investigated how memory retrieval might be affected by stress-induced cortisol release, independently of sympathetic nervous system stress responses. Thirty-two healthy…
Montgomery, James W.; Evans, Julia L.
Purpose: This study investigated the association of 2 mechanisms of working memory (phonological short-term memory [PSTM], attentional resource capacity/allocation) with the sentence comprehension of school-age children with specific language impairment (SLI) and 2 groups of control children. Method: Twenty-four children with SLI, 18 age-matched…
Teather, Lisa A.; Wurtman, Richard J.
The authors previously showed that dietary cytidine (5')-diphosphocholine (CDP-choline) supplementation could protect against the development of memory deficits in aging rats. In the present study, younger rats exposed to impoverished environmental conditions and manifesting hippocampal-dependent memory impairments similar to those observed in the…
Aleisa, A M; Helal, G; Alhaider, I A; Alzoubi, K H; Srivareerat, M; Tran, T T; Al-Rejaie, S S; Alkadhi, K A
Rapid eye movement (REM) sleep deprivation (SD) is implicated in impairment of spatial learning and memory and hippocampal long-term potentiation (LTP). An increase in nicotine consumption among habitual smokers and initiation of tobacco use by nonsmokers was observed during SD. Although nicotine treatment was reported to attenuate the impairment of learning and memory and LTP associated with several mental disorders, the effect of nicotine on SD-induced learning and memory impairment has not been studied. Modified multiple platform paradigm was used to induce SD for 24 or 48 h during which rats were injected with saline or nicotine (1 mg kg(-1) s.c.) twice a day. In the radial arm water maze (RAWM) task, 24- or 48-h SD significantly impaired learning and short-term memory. In addition, extracellular recordings from CA1 and dentate gyrus (DG) regions of the hippocampus in urethane anesthetized rats showed a significant impairment of LTP after 24- and 48-h SD. Treatment of normal rats with nicotine for 24 or 48 h did not enhance spatial learning and memory or affect magnitude of LTP in the CA1 and DG regions. However, concurrent, acute treatment of rats with nicotine significantly attenuated SD-induced impairment of learning and STM and prevented SD-induced impairment of LTP in the CA1 and DG regions. These results show that acute nicotine treatment prevented the deleterious effect of sleep loss on cognitive abilities and synaptic plasticity.
Smith, J Carson; Nielson, Kristy A; Woodard, John L; Seidenberg, Michael; Verber, Matthew D; Durgerian, Sally; Antuono, Piero; Butts, Alissa M; Hantke, Nathan C; Lancaster, Melissa A; Rao, Stephen M
The effect of physical activity (PA) on functional brain activation for semantic memory in amnestic mild cognitive impairment (aMCI) was examined using event-related functional magnetic resonance imaging during fame discrimination. Significantly greater semantic memory activation occurred in the left caudate of High- versus Low-PA patients, (P=0.03), suggesting PA may enhance memory-related caudate activation in aMCI.
Archibald, Lisa M. D.; Joanisse, Marc; Edmunds, Alan
Study of the developmental relationship between language and working memory skills has only just begun, despite the prominent role of their interdependency in some theoretical accounts of developmental language impairments. Recently, Archibald and Joanisse (2009) identified children with specific language impairment (SLI), or specific working…
Wong, Ling M.; Riggins, Tracy; Harvey, Danielle; Cabaral, Margarita; Simon, Tony J.
Individuals with chromosome 22q11.2 deletion syndrome (22q11.2DS) have been shown to have impairments in processing spatiotemporal information. The authors examined whether children with 22q11.2DS exhibit impairments in spatial working memory performance due to these weaknesses, even when controlling for maintenance of attention. Children with…
Yau, Po Lai; Kluger, Alan; Borod, Joan C.; Convit, Antonio
Background Verbal memory impairment is well documented in type 2 diabetes mellitus (T2DM) but to date, the neural substrates remain unclear. The present study evaluated verbal memory and ascertained the degree of frontal and temporal lobe involvement in the anticipated verbal memory impairment among adults with T2DM. Methods Forty-six late middle-aged and elderly adults with T2DM and 50 age-, sex-, and education-matched adults without T2DM underwent medical evaluation, verbal memory assessment, and brain MRI evaluations. Results As anticipated, participants with T2DM had clear verbal memory impairments. Consistent with prior reports, we found volume reductions restricted to the hippocampus. Our diffusion tensor imaging analysis revealed that participants with T2DM had extensive cerebral gray and white matter microstructural abnormalities predominantly in the left hemisphere, with a larger concentration present in the temporal lobe. In contrast, we uncovered mostly non-specific microstructural abnormalities in the absence of tissue loss in the frontal lobe. Of great importance, we present the first evidence among participants with T2DM linking verbal memory impairment and compromised microstructural integrity of the left parahippocampal gyrus, a key memory-relevant structure. Conclusions Our results suggest that the hippocampus and parahippocampal gyrus may be particularly vulnerable to the deleterious effects of T2DM. The parahippocampal gyrus in particular may play a crucial role in the verbal memory impairments frequently reported in T2DM. Future studies should employ methods such as resting state functional magnetic resonance imaging and diffusion tensor imaging tractography to better characterize network connectivity, which may help further characterize the verbal memory impairment frequently reported in T2DM. PMID:24417611
Santa, Tomofumi; Kirino, Yutaka; Watanabe, Satoshi; Shirahata, Takaaki; Tsunoda, Makoto
The terrestrial slug "Limax" is able to acquire short-term and long-term memories during aversive odor-taste associative learning. We investigated the effect of the selective serotonergic neurotoxin 5,7-dihydroxytryptamine (5,7-DHT) on memory. Behavioral studies indicated that 5,7-DHT impaired short-term memory but not long-term memory. HPLC…
Souza, Ana Cristina G; Bruning, César A; Acker, Carmine I; Neto, José S S; Nogueira, Cristina W
Taking into account the memory-enhancing properties of 2-phenylethynyl-butyltellurium (PEBT) and the constant search for drugs that improve cognitive performance, the present study was designed to investigate the effect of PEBT on cognitive impairment induced by scopolamine in mice. PEBT (10 mg/kg, gavage) was administered to mice 1 h before the probe trial in the Morris water maze task. Memory impairment was induced by scopolamine (1 mg/kg, intraperitoneally) 30 min before the probe trial. PEBT significantly ameliorated the scopolamine-induced impairment of long-term memory, as indicated by a decrease in escape latency and an increase in the number of crossings of the platform location when compared with the amnesic mice. To evaluate the effect of PEBT on different phases of memory (acquisition, consolidation, and retrieval) impaired by scopolamine, the step-down inhibitory avoidance task was used. Scopolamine was administered 30 min before training (acquisition), test (retrieval), or immediately after training (consolidation). PEBT, administered 30 min before scopolamine, increased step-down latency in memory-impaired mice, improving the consolidation and retrieval stages, but not acquisition. No significant alterations in locomotor or exploratory behaviors were found in animals treated with PEBT and/or scopolamine. PEBT improved memory deficits during consolidation and retrieval induced by scopolamine.
Soung, Hung-Sheng; Wang, Mao-Hsien; Tseng, Hsiang-Chien; Fang, Hsu-Wei; Chang, Kuo-Chi
Stress induces reactive oxygen species (ROS) and causes alterations in brain cytoarchitecture and cognition. Green tea has potent antioxidative properties especially the tea catechin (-) epigallocatechin-3-gallate (EGCG). These powerful antioxidative properties are able to protect against various oxidative damages. In this study we investigated the impact of stress on rats' locomotor activity, learning and memory. Many tea catechins, including EGCG, were examined for their possible therapeutic effects in treating stress-induced impairment. Our results indicated that locomotor activity was decreased, and the learning and memory were impaired in stressed rats (SRs). EGCG treatment was able to prevent the decreased locomotor activity as well as improve the learning and memory in SRs. EGCG treatment was also able to reduce the increased oxidative status in SRs' hippocampi. The above results suggest a therapeutic effect of EGCG in treating stress-induced impairment of learning and memory, most likely by means of its powerful antioxidative properties.
Zhou, Baozhu; Li, Maoxing; Cao, Xinyuan; Zhang, Quanlong; Liu, Yantong; Ma, Qiang; Qiu, Yan; Luan, Fei; Wang, Xianmin
Exposure to hypobaric hypoxia causes oxidative stress, neuronal degeneration and apoptosis that leads to memory impairment. Though oxidative stress contributes to neuronal degeneration and apoptosis in hypobaric hypoxia, the ability for phenylethanoid glycosides of Pedicularis muscicola Maxim (PhGs) to reverse high altitude memory impairment has not been studied. Rats were supplemented with PhGs orally for a week. After the fourth day of drug administration, rats were exposed to a 7500 m altitude simulation in a specially designed animal decompression chamber for 3 days. Spatial memory was assessed by the 8-arm radial maze test before and after exposure to hypobaric hypoxia. Histological assessment of neuronal degeneration was performed by hematoxylin-eosin (HE) staining. Changes in oxidative stress markers and changes in the expression of the apoptotic marker, caspase-3, were assessed in the hippocampus. Our results demonstrated that after exposure to hypobaric hypoxia, PhGs ameliorated high altitude memory impairment, as shown by the decreased values obtained for reference memory error (RME), working memory error (WME), and total error (TE). Meanwhile, administration of PhGs decreased hippocampal reactive oxygen species levels and consequent lipid peroxidation by elevating reduced glutathione levels and enhancing the free radical scavenging enzyme system. There was also a decrease in the number of pyknotic neurons and a reduction in caspase-3 expression in the hippocampus. These findings suggest that PhGs may be used therapeutically to ameliorate high altitude memory impairment.
Fernandes-Santos, Luciano; Patti, Camilla L; Zanin, Karina A; Fernandes, Helaine A; Tufik, Sergio; Andersen, Monica L; Frussa-Filho, Roberto
The deleterious effects of paradoxical sleep deprivation on memory processes are well documented. However, non-selective sleep deprivation occurs more commonly in modern society and thus represents a better translational model. We have recently reported that acute total sleep deprivation (TSD) for 6 h immediately before testing impaired performance of male mice in the plus-maze discriminative avoidance task (PM-DAT) and in the passive avoidance task (PAT). In order to extend these findings to females, we examined the effect of (pre-test) TSD on the retrieval of different memory tasks in both male and female mice. Animals were tested using 3 distinct memory models: 1) conditioning fear context (CFC), 2) PAT and 3) PM-DAT. In all experiments, animals were totally sleep-deprived by the gentle interference method for 6h immediately before being tested. In the CFC task and the PAT, TSD induced memory impairment regardless of sex. In PM-DAT, the memory impairing effects of TSD were greater in females. Collectively, our results confirm the impairing effect of TSD on emotional memory retrieval and demonstrate that it can be higher in female mice depending on the memory task evaluated.
Allen, Timothy A.; Morris, Andrea M.; Stark, Shauna M.; Fortin, Norbert J.; Stark, Craig E. L.
Typical aging is associated with diminished episodic memory performance. To improve our understanding of the fundamental mechanisms underlying this age-related memory deficit, we previously developed an integrated, cross-species approach to link converging evidence from human and animal research. This novel approach focuses on the ability to…
Jacobs, Joshua; Miller, Jonathan; Lee, Sang Ah; Coffey, Tom; Watrous, Andrew J; Sperling, Michael R; Sharan, Ashwini; Worrell, Gregory; Berry, Brent; Lega, Bradley; Jobst, Barbara C; Davis, Kathryn; Gross, Robert E; Sheth, Sameer A; Ezzyat, Youssef; Das, Sandhitsu R; Stein, Joel; Gorniak, Richard; Kahana, Michael J; Rizzuto, Daniel S
Deep brain stimulation (DBS) has shown promise for treating a range of brain disorders and neurological conditions. One recent study showed that DBS in the entorhinal region improved the accuracy of human spatial memory. Based on this line of work, we performed a series of experiments to more fully characterize the effects of DBS in the medial temporal lobe on human memory. Neurosurgical patients with implanted electrodes performed spatial and verbal-episodic memory tasks. During the encoding periods of both tasks, subjects received electrical stimulation at 50 Hz. In contrast to earlier work, electrical stimulation impaired memory performance significantly in both spatial and verbal tasks. Stimulation in both the entorhinal region and hippocampus caused decreased memory performance. These findings indicate that the entorhinal region and hippocampus are causally involved in human memory and suggest that refined methods are needed to use DBS in these regions to improve memory.
Nikoui, Vahid; Javadi-Paydar, Mehrak; Salehi, Mahtab; Behestani, Selda; Dehpour, Ahmad-Reza
Lithium is a drug used for the treatment of bipolar disorder. It has several mechanisms of action, and recently it is shown that lithium can antagonize the 5-HT1B/1D serotonin receptors. Sumatriptan is a 5-HT1B/1D receptor agonist used for the treatment of cluster headaches and migraine which might cause memory impairment as a potential side effect. In this study, effects of lithium on sumatriptan-induced memory impairment have been determined in a two-trial recognition Y-maze and passive avoidance tests. Male mice weighing 25-30 g were divided into several groups randomly. In Y-maze test, effects of lithium (1,5,10,20,40,80 mg/kg) and sumatriptan (1,5,10 mg/kg) were assessed on memory acquisition, then lithium (0.1,1,10 mg/kg) and sumatriptan (1,10 mg/kg) were studied in passive avoidance test. Effects of lithium (1mg/kg) on sumatriptan (10 mg/kg)-induced memory impairment were studied in both of tests. The present study demonstrated that sumatriptan impaired memory in Y-maze and passive avoidance tests (P<0.05, P<0.01, respectively). Lithium did not show any significant effect on memory function compared to saline-treated control group in both tests (P>0.05), but significantly reversed sumatriptan-induced memory impairment in Y-maze and passive avoidance tests (P<0.001, P<0.05, respectively). It is concluded that lithium reverses the sumatriptan-induced memory impairment probably through 5-HT1B/1D receptors antagonism.
Shin, Ki Young
Progressive memory impairment such as that associated with depression, stroke, and Alzheimer's disease (AD) can interfere with daily life. In particular, AD, which is a progressive neurodegenerative disorder, prominently features a memory and learning impairment that is related to changes in acetylcholine and abnormal β-amyloid (Aβ) deposition in the brain. In the present study, we investigated the effects of dehydroevodiamine·HCl (DHED) on cognitive improvement and the related mechanism in memory-impaired rat models, namely, a scopolamine-induced amnesia model and a Aβ1-42-infused model. The cognitive effects of DHED were measured using a water maze test and a passive avoidance test in the memory-impaired rat models. The results demonstrate that DHED (10 mg/kg, p.o.) and Donepezil (1 mg/kg, p.o.) ameliorated the spatial memory impairment in the scopolamine-induced amnestic rats. Moreover, DHED significantly improved learning and memory in the Aβ1-42-infused rat model. Furthermore, the mechanism of these behavioral effects of DHED was investigated using a cell viability assay, reactive oxygen species (ROS) measurement, and intracellular calcium measurement in primary cortical neurons. DHED reduced neurotoxicity and the production of Aβ-induced ROS in primary cortical neurons. In addition, similar to the effect of MK801, DHED decreased intracellular calcium levels in primary cortical neurons. Our results suggest that DHED has strong protective effects against cognitive impairments through its antioxidant activity and inhibition of neurotoxicity and intracellular calcium. Thus, DHED may be an important therapeutic agent for memory-impaired symptoms. PMID:28066141
Kuypers, KPC; Torre, R; Farre, M; Pujadas, M; Ramaekers, JG
Background Ecstasy use is commonly linked with memory deficits in abstinent ecstasy users. Similar impairments are being found during ecstasy intoxication after single doses of ± 3,4 metylenedioxymethamphetamine (MDMA). The concordance of memory impairments during intoxication and abstinence suggests a similar neuropharmacological mechanism underlying acute and chronic memory impairments. The mechanism underlying this impairment is to date not known. We hypothesized that cortisol might play an important role in this mechanism as cortisol, implicated in the regulation of memory performance, can be brought out of balance by stressors like MDMA. Methods In the present study, we aimed to block the MDMA-induced acute memory defect by giving participants a cortisol synthesis inhibitor (metyrapone) together with a single dose of MDMA. Seventeen polydrug MDMA users entered this placebo-controlled within subject study with four treatment conditions. The treatments consisted of MDMA (75 mg) and metyrapone (750 mg), alone and in combination, and double placebo. Pre-treatment with metyrapone or Placebo occurred 1 h prior to MDMA or Placebo administration. Memory performance was tested at peak drug concentrations by means of several memory tests. Cortisol levels were determined in blood and oral fluid; this served as a control measure to see whether manipulations were effective. Results Main findings indicated that whereas treatment with metyrapone blocked the expected MDMA-induced increase in cortisol levels in blood, it did not prevent the MDMA-induced memory deficit from happening. Conclusion We therefore conclude that MDMA-induced increments in cortisol concentrations are not related to MDMA-induced memory impairments. PMID:22946487
Pagnussat, N; Almeida, A S; Marques, D M; Nunes, F; Chenet, G C; Botton, P H S; Mioranzza, S; Loss, C M; Cunha, R A; Porciúncula, L O
Background and Purpose Caffeine (a non-selective adenosine receptor antagonist) prevents memory deficits in aging and Alzheimer’s disease, an effect mimicked by adenosine A2A receptor, but not A1 receptor, antagonists. Hence, we investigated the effects of adenosine receptor agonists and antagonists on memory performance and scopolamine-induced memory impairment in mice. Experimental Approach We determined whether A2A receptors are necessary for the emergence of memory impairments induced by scopolamine and whether A2A receptor activation triggers memory deficits in naïve mice, using three tests to assess short-term memory, namely the object recognition task, inhibitory avoidance and modified Y-maze. Key Results Scopolamine (1.0 mg·kg−1, i.p.) impaired short-term memory performance in all three tests and this scopolamine-induced amnesia was prevented by the A2A receptor antagonist (SCH 58261, 0.1–1.0 mg·kg−1, i.p.) and by the A1 receptor antagonist (DPCPX, 0.2–5.0 mg·kg−1, i.p.), except in the modified Y-maze where only SCH58261 was effective. Both antagonists were devoid of effects on memory or locomotion in naïve rats. Notably, the activation of A2A receptors with CGS 21680 (0.1–0.5 mg·kg−1, i.p.) before the training session was sufficient to trigger memory impairment in the three tests in naïve mice, and this effect was prevented by SCH 58261 (1.0 mg·kg−1, i.p.). Furthermore, i.c.v. administration of CGS 21680 (50 nmol) also impaired recognition memory in the object recognition task. Conclusions and Implications These results show that A2A receptors are necessary and sufficient to trigger memory impairment and further suggest that A1 receptors might also be selectively engaged to control the cholinergic-driven memory impairment. PMID:25939452
Shrager, Yael; Gold, Jeffrey J.; Hopkins, Ramona O.; Squire, Larry R.
A recent proposal that structures of the medial temporal lobe support visual perception in addition to memory challenges the long-standing idea that the ability to acquire new memories is separable from other cognitive and perceptual functions. In four experiments, we have put this proposal to a rigorous test. Six memory-impaired patients with well characterized lesions of either the hippocampal region or the hippocampal region plus additional medial temporal lobe structures were assessed on difficult tests of visual perceptual discrimination. Across all four experiments, the patients performed as well as controls. The results show that visual perception is intact in memory-impaired patients with damage to the medial temporal lobe even when perception is assessed with challenging tasks. Furthermore, the results support the principle that the ability to acquire new memories is a distinct cerebral function, dissociable from other perceptual and cognitive functions. PMID:16495450
Mammarella, Irene C; Coltri, Silvia; Lucangeli, Daniela; Cornoldi, Cesare
We report the case of B.A., an 11-year-old child with a nonverbal (visuospatial) learning disability (NLD). Detailed psychometric and neuropsychological assessment on visuospatial working memory (VSWM) revealed specific simultaneous-spatial working memory impairment. A treatment targeting simultaneous-spatial working memory was given to B.A. for seven sessions (over one month); this resulted in improvement of simultaneous-spatial working memory, with the benefit that the training was maintained after six months. Discussion of clinical and theoretical implications is given, taking account of the distinctions that can be made between the different components of visuospatial working memory and different subtypes of NLD, thus allowing the tailoring of specific training to target the impaired VSWM component.
Pan, Jingrui; He, Lei; Li, Xiangpen; Li, Mei; Zhang, Xiaoni; Venesky, Jacob; Li, Yi; Peng, Ying
Morphine abuse in treating severe and chronic pain has become a worldwide problem. But, chronic morphine exposure can cause memory impairment with its mechanisms not fully elucidated by past research sstudies which all focused on the harmful effects of morphine. Autophagy is an important pathway for cells to maintain survival. Here we showed that repeated morphine injection into C57BL/6 mice at a dose of 15 mg/kg per day for 7 days activated autophagic flux mainly in the hippocampi, especially in neurons of hippocampal CA1 region and microglia, with spatial memory impairment confirmed by Morris water maze test. Autophagy inhibition by 3-methyladenine obviously aggravates this morphine-induced memory impairment, accompanied with increased cell deaths in stratum pyramidale of hippocampal CA1, CA3, and DG regions and the activation of microglia to induce inflammation in hippocampus, such as upregulated expression of TNF-α, IL-1β, IL-6, and iNOS, as well as NF-κB' s activation, while morphine alone promoted microglial immunosuppression in hippocampus with autophagy activation which was also confirmed in primary microglia. Taken together, our data indicates that autophagy activating in hippocampal cells can alleviate the memory impairment caused by morphine, by decreasing neuronal deaths in hippocampus and suppressing inflammation in hippocampal microglia, implying that modulating the activation of autophagy might be a promising method to prevent or treat the memory impairment caused by morphine.
Olver, James S; Pinney, Myra; Maruff, Paul; Norman, Trevor R
Few studies have investigated the effect of an acute psychosocial stress paradigm on impaired attention and working memory in humans. Further, the duration of any stress-related cognitive impairment remains unclear. The aim of this study was to examine the effect of an acute psychosocial stress paradigm, the Trier Social Stress, on cognitive function in healthy volunteers. Twenty-three healthy male and female subjects were exposed to an acute psychosocial stress task. Physiological measures (salivary cortisol, heart rate and blood pressure) and subjective stress ratings were measured at baseline, in anticipation of stress, immediately post-stress and after a period of rest. A neuropsychological test battery including spatial working memory and verbal memory was administered at each time point. Acute psychosocial stress produced significant increases in cardiovascular and subjective measures in the anticipatory and post-stress period, which recovered to baseline after rest. Salivary cortisol steadily declined over the testing period. Acute psychosocial stress impaired delayed verbal recall, attention and spatial working memory. Attention remained impaired, and delayed verbal recall continued to decline after rest. Acute psychosocial stress is associated with an impairment of a broad range of cognitive functions in humans and with prolonged abnormalities in attention and memory.
Aleisa, A M; Alzoubi, K H; Alkadhi, K A
Rapid eye movement sleep deprivation (REM-SD) is associated with spatial learning and memory impairment. During REM-SD, an increase in nicotine consumption among habitual smokers and initiation of tobacco use by non-smokers have been reported. We have shown recently that nicotine treatment prevented learning and memory impairments associated with REM-SD. We now report the interactive effects of post-learning REM-SD and/or nicotine. The animals were first trained on the radial arm water maze (RAWM) task, then they were REM-sleep deprived using the modified multiple platform paradigm for 24h. During REM-SD period, the rats were injected with saline or nicotine (1mg/kg s.c. every 12h: a total of 3 injections). The animals were tested for long-term memory in the RAWM at the end of the REM-SD period. The 24h post-learning REM-SD significantly impaired long-term memory. However, nicotine treatment reversed the post-learning REM-SD-induced impairment of long-term memory. On the other hand, post-learning treatment of normal rats with nicotine for 24h enhanced long-term memory. These results indicate that post-learning acute nicotine treatment prevented the deleterious effect of REM-SD on cognitive abilities.
Sweeney-Reed, Catherine M.; Riddell, Patricia M.; Ellis, Judi A.; Freeman, Jayne E.; Nasuto, Slawomir J.
The goal of this research was to investigate the changes in neural processing in mild cognitive impairment. We measured phase synchrony, amplitudes, and event-related potentials in veridical and false memory to determine whether these differed in participants with mild cognitive impairment compared with typical, age-matched controls. Empirical mode decomposition phase locking analysis was used to assess synchrony, which is the first time this analysis technique has been applied in a complex cognitive task such as memory processing. The technique allowed assessment of changes in frontal and parietal cortex connectivity over time during a memory task, without a priori selection of frequency ranges, which has been shown previously to influence synchrony detection. Phase synchrony differed significantly in its timing and degree between participant groups in the theta and alpha frequency ranges. Timing differences suggested greater dependence on gist memory in the presence of mild cognitive impairment. The group with mild cognitive impairment had significantly more frontal theta phase locking than the controls in the absence of a significant behavioural difference in the task, providing new evidence for compensatory processing in the former group. Both groups showed greater frontal phase locking during false than true memory, suggesting increased searching when no actual memory trace was found. Significant inter-group differences in frontal alpha phase locking provided support for a role for lower and upper alpha oscillations in memory processing. Finally, fronto-parietal interaction was significantly reduced in the group with mild cognitive impairment, supporting the notion that mild cognitive impairment could represent an early stage in Alzheimer’s disease, which has been described as a ‘disconnection syndrome’. PMID:23118992
Nategh, Mohsen; Nikseresht, Sara; Khodagholi, Fariba; Motamedi, Fereshteh
Nucleus incertus (NI) is a pontine nucleus which releases mainly GABA and relaxin-3 in rats. Its suggested functions include response to stress, arousal, and modulation of hippocampal theta rhythm. Since the role of NI in learning and memory has not been well characterized, therefore the involvement of this nucleus in spatial learning and memory and the aftermath hippocampal levels of c-fos and pCREB were evaluated. NI was targeted by implanting cannula in male rats. For reference memory, NI was inactivated by lidocaine (0.4 μl, 4%) at three stages of acquisition, consolidation and retrieval in Morris water maze paradigm. For working memory, NI was inactivated in acquisition and retrieval phases. Injection of lidocaine prior to the first training session of reference memory significantly increased the distance moved, suggesting that inactivation of NI delays acquisition in this spatial task. Inactivation also interfered with the retrieval phase of spatial reference memory, as the time in target quadrant for lidocaine group was less, and the escape latency was higher compared to the control group. However, no difference was observed in the consolidation phase. In the working memory task, with inter-trial intervals of 75 min, the escape latency was higher when NI was inactivated in the retrieval phase. In addition, c-fos and pCREB/CREB levels decreased in NI-inhibited rats. This study suggests that nucleus incertus might participate in acquisition of spatial reference, and retrieval of both spatial reference and working memory. Further studies should investigate possible roles of NI in the hippocampal plasticity.
Guan, Zhiwei; Peng, Xuwen; Fang, Jidong
Loss of sleep may result in memory impairment. However, little is known about the biochemical basis for memory deficits induced by sleep deprivation. Extracellular signal-regulated kinase (ERK) is involved in memory consolidation in different tasks. Phosphorylation of ERK is necessary for its activation and is an important step in mediating neuronal responses to synaptic activities. The aim of the present study was to determine the effects of total sleep deprivation (TSD) on memory and ERK phosphorylation in the brain. Rats were trained in Morris water maze to find a hidden platform (a spatial task) or a visible platform (a nonspatial task) after 6 h TSD or spontaneous sleep. TSD had no effect on spatial learning, but significantly impaired spatial memory tested 24 h after training. Nonspatial learning and memory were not impaired by TSD. Phospho-ERK levels in the hippocampus were significantly reduced after 6 h TSD compared to the controls and returned to the control levels after 2 h recovery sleep. Total ERK1 and ERK2 were slightly increased after 6 h TSD and returned to the control levels after 2 h recovery sleep. These alterations were not observed in the cortex after TSD. Protein phosphotase-1 and mitogen-activated protein kinase phosphatase-2, which dephosphorylates phospho-ERK, were also measured, but they were not altered by TSD. The impairments of both spatial memory and ERK phosphorylation indicate that the hippocampus is vulnerable to sleep loss. These results are consistent with the idea that decreased ERK activation in the hippocampus is involved in sleep deprivation-induced spatial memory impairment.
Rolls, Asya; Colas, Damien; Adamantidis, Antoine; Carter, Matt; Lanre-Amos, Tope; Heller, H Craig; de Lecea, Luis
Memory consolidation has been proposed as a function of sleep. However, sleep is a complex phenomenon characterized by several features including duration, intensity, and continuity. Sleep continuity is disrupted in different neurological and psychiatric conditions, many of which are accompanied by memory deficits. This finding has raised the question of whether the continuity of sleep is important for memory consolidation. However, current techniques used in sleep research cannot manipulate a single sleep feature while maintaining the others constant. Here, we introduce the use of optogenetics to investigate the role of sleep continuity in memory consolidation. We optogenetically targeted hypocretin/orexin neurons, which play a key role in arousal processes. We used optogenetics to activate these neurons at different intervals in behaving mice and were able to fragment sleep without affecting its overall amount or intensity. Fragmenting sleep after the learning phase of the novel object recognition (NOR) task significantly decreased the performance of mice on the subsequent day, but memory was unaffected if the average duration of sleep episodes was maintained at 62-73% of normal. These findings demonstrate the use of optogenetic activation of arousal-related nuclei as a way to systematically manipulate a specific feature of sleep. We conclude that regardless of the total amount of sleep or sleep intensity, a minimal unit of uninterrupted sleep is crucial for memory consolidation.
Nawata, Yoko; Hiranita, Takato; Yamamoto, Tsuneyuki
(+/-)-3,4-Methylenedioxymethamphetamine (MDMA, 'Ecstasy') abusers have persistent neuropsychiatric deficits including memory impairments after the cessation of abuse. On the other hand, cannabinoid CB(1) receptors have been implicated in learning/memory, and are highly expressed in the hippocampus, a region of the brain believed to have an important function in certain forms of learning and memory. In this study, we clarified the mechanism underlying the cognitive impairment that develops during MDMA withdrawal from the standpoint of the cannabinoid CB(1) receptors. Mice were administered MDMA (10 mg/kg, i.p.) once a day for 7 days. On the 7th day of withdrawal, a novel object recognition task was performed and the amount of cannabinoid CB(1) receptor protein was measured with western blotting. Recognition performance was impaired on the 7th day of withdrawal. This impairment was blocked by AM251, a cannabinoid CB(1) receptor antagonist, administered 30 min before the training trial or co-administered with MDMA. At this time, the level of cannabinoid CB(1) receptor protein increased significantly in the hippocampus but not the prefrontal cortex or striatum. This increase of CB(1) receptor protein in the hippocampus was also blocked by the co-administration of AM251. Furthermore, CB(1) receptor knockout mice showed no impairment of recognition performance on the withdrawal from MDMA. The impairment of recognition memory during withdrawal from MDMA may result from the activation of cannabinoid CB(1) receptors in the hippocampus.
Smith, Christine N; Urgolites, Zhisen J; Hopkins, Ramona O; Squire, Larry R
Declarative memory for rapidly learned, novel associations is thought to depend on structures in the medial temporal lobe (MTL), whereas associations learned more gradually can sometimes be supported by nondeclarative memory and by structures outside the MTL. A recent study suggested that even rapidly learned associations can be supported by structures outside the MTL when an incidental encoding procedure termed "fast mapping" (FM) is used. We tested six memory-impaired patients with bilateral damage to hippocampus and one patient with large bilateral lesions of the MTL. Participants saw photographs and names of animals, plants, and foods that were previously unfamiliar (e.g., mangosteen). Instead of asking participants to study name-object pairings for a later memory test (as with traditional memory instructions), participants answered questions that allowed them to infer which object corresponded to a particular name. In a second condition, participants learned name-object associations of unfamiliar items by using standard, explicit encoding instructions (e.g., remember the mangosteen). In FM and explicit encoding conditions, patients were impaired (and performed no better than a group that was given the same tests but had not previously studied the material). The same results were obtained in a second experiment that used the same procedures with modifications to allow for more robust learning and more reliable measures of performance. Thus, our results with the FM procedure and memory-impaired patients yielded the same deficits in learning and memory that have been obtained by using other more traditional paradigms.
Kalechstein, Ari D; De La Garza, Richard; Newton, Thomas F
Modafinil improves working memory in healthy subjects and individuals diagnosed with schizophrenia and Attention Deficit/Hyperactivity Disorder, though the effects of modafinil have not been evaluated on working memory in methamphetamine-dependent subjects. This double-blind, placebo-controlled study evaluated whether a daily dose of 400 mg of modafinil, administered over three consecutive days, would enhance performance on a measure of working memory relative to test performance at baseline and following 3 days of placebo administration in 11 methamphetamine addicted, nontreatment-seeking volunteers. The results revealed that participants demonstrating relatively poor performance on the third day of a 3-day washout period (ie, at baseline), showed significant improvement on measures of working memory, but not on measures of episodic memory or information processing speed. In contrast, for participants demonstrating relatively high performance at baseline, modafinil administration did not affect test scores. The findings provide an initial indication that modafinil can reverse methamphetamine-associated impairments in working memory.
Li, Xiaoshu; Wang, Haibao; Tian, Yanghua; Zhou, Shanshan; Li, Xiaohu; Wang, Kai; Yu, Yongqiang
Background: Discrepancies persist regarding retainment of emotional enhancement of memory (EEM) in mild cognitive impairment (MCI) and early Alzheimer's disease (AD) patients.In addition, the neural mechanisms are still poorly understood, little is known about emotional memory related changes in white matter (WM). Objective: To observe whether EEM is absent in amnestic MCI (aMCI) and AD patients, and to investigate if emotional memory is associated with WM connections and gray matters (GM) of the limbic system networks. Methods: Twenty-one AD patients, 20 aMCI patients and 25 normal controls participated in emotional picture recognition tests and MRI scanning. Tract-based spatial statistics (TBSS) and voxel-based morphometry (VBM) methods were used to determine white and gray matter changes of patients. Fourteen regions of interest (ROI) of WM and 20 ROIs of GM were then selected for the correlation analyses with behavioral scores. Results: The EEM effect was lost in AD patients. Both white and gray matter of the limbic system networks were impaired in AD patients. Significant correlations or tendencies between the bilateral uncinate fasciculus, corpus callosum (genu and body), left cingulum bundle, left parahippocampal WM and the recognition sensitivity of emotional valence pictures, and significant correlations or tendencies between the splenium of corpus callosum, left cingulum bundle, left crus of fornix and stria terminalis and the recognition sensitivity of EEM were found. The volume of left amygdala, bilateral insula, medial frontal lobe, anterior and middle cingulum gyrus were positively correlated with the recognition sensitivity of emotional photos, and the right precuneus was positively correlated with the negative EEM effect. However, the affected brain areas of aMCI patients were more localized, and aMCI patients benefited only from positive stimuli. Conclusion: There are impairments of the limbic system networks of AD patients. Damaged WM connections
Tailby, Rebecca; Haslam, Catherine
In rehabilitating individuals who demonstrate severe memory impairment, errorless learning techniques have proven particularly effective. Prevention of errors during acquisition of information leads to better memory than does learning under errorful conditions. This paper presents results of a study investigating errorless learning in three patient groups: those demonstrating mild, moderate, and severe memory impairments. The first goal of the study was to trial a new version of errorless learning, one encouraging more active participation in learning by patients via the use of elaboration and self-generation. This technique led to significantly better memory performance than seen under standard errorless conditions. This finding highlights the value of encouraging active and meaningful involvement by patients in errorless learning, to build upon the benefits flowing from error prevention. A second goal of the study was to clarify the mechanisms underlying errorless learning. Memory performance under errorless and errorful conditions was compared within and across each group of patients, to facilitate theoretical insight into the memory processes underlying performance. The pattern of results observed was equivocal. The data most strongly supported the hypothesis that the benefits seen under errorless learning reflect the operation of residual explicit memory processes, however a concurrent role for implicit memory processes was not ruled out.
Hales, Jena B.; Ocampo, Amber C.; Broadbent, Nicola J.; Clark, Robert E.
Spatial memory in rodents can be erased following the infusion of zeta inhibitory peptide (ZIP) into the dorsal hippocampus via indwelling guide cannulas. It is believed that ZIP impairs spatial memory by reversing established late-phase long-term potentiation (LTP). However, it is unclear whether other forms of hippocampus-dependent memory, such as recognition memory, are also supported by hippocampal LTP. In the current study, we tested recognition memory in rats following hippocampal ZIP infusion. In order to combat the limited targeting of infusions via cannula, we implemented a stereotaxic approach for infusing ZIP throughout the dorsal, intermediate, and ventral hippocampus. Rats infused with ZIP 3–7 days after training on the novel object recognition task exhibited impaired object recognition memory compared to control rats (those infused with aCSF). In contrast, rats infused with ZIP 1 month after training performed similar to control rats. The ability to form new memories after ZIP infusions remained intact. We suggest that enhanced recognition memory for recent events is supported by hippocampal LTP, which can be reversed by hippocampal ZIP infusion. PMID:26380123
Jin, Seong-Uk; Park, Jang Woo; Kim, Yang-Tae; Ryeom, Hun-Kyu; Lee, Jongmin; Suh, Kyung Jin; Kim, Suk Hwan; Park, Sin-Jae; Jeong, Kyoung Sook; Ham, Jung-O; Kim, Yangho; Chang, Yongmin
Background It is well known that lead exposure induces neurotoxic effects, which can result in a variety of neurocognitive dysfunction. Especially, occupational lead exposures in adults are associated with decreases in cognitive performance including working memory. Despite recent advances in human neuroimaging techniques, the neural correlates of lead-exposed cognitive impairment remain unclear. Therefore, this study was aimed to compare the neural activations in relation to working memory function between the lead-exposed subjects and healthy controls. Methodology/Principal Findings Thirty-one lead-exposed subjects and 34 healthy subjects performed an n-back memory task during MRI scan. We performed fMRI using the 1-back and 2-back memory tasks differing in cognitive demand. Functional MRI data were analyzed using within- and between-group analysis. We found that the lead-exposed subjects showed poorer working memory performance during high memory loading task than the healthy subjects. In addition, between-group analyses revealed that the lead-exposed subjects showed reduced activation in the dorsolateral prefrontal cortex, ventrolateral prefrontal cortex, pre supplementary motor areas, and inferior parietal cortex. Conclusions/Significance Our findings suggest that functional abnormalities in the frontoparietal working memory network might contribute to impairments in maintenance and manipulation of working memory in the lead-exposed subjects. PMID:25141213
Kunisawa, K; Nakashima, N; Nagao, M; Nomura, T; Kinoshita, S; Hiramatsu, M
Betaine plays important roles that include acting as a methyl donor and converting homocysteine (Hcy) to methionine. Elevated plasma Hcy levels are known as hyperhomocysteinemia (HHcy) and contribute to impairments of learning and memory. Although it is commonly known that betaine plays an important role in Hcy metabolism, the effects of betaine on Hcy-induced memory impairment have not been investigated. Previously, we demonstrated the beneficial effects of betaine on acute stress and lipopolysaccharide-induced memory impairment. In the present study, we investigated whether betaine ameliorates Hcy-induced memory impairment and the underlying mechanisms of this putative effect. Mice were treated with Hcy (0.162mg/kg, s.c.) twice a day for nine days, and betaine (25mg/kg, s.c.) was administered 30min before the Hcy injections. The memory functions were evaluated using a spontaneous alternation performance test (Y-maze) at seven days and a step-down type passive avoidance test (SD) at nine and ten days after Hcy injection. We found that betaine suppressed the memory impairment induced by repeated Hcy injections. However, the blood concentrations of Hcy were significantly increased in the Hcy-treated mice immediately after the passive avoidance test, and betaine did not prevent this increase. Furthermore, Hcy induces redox stress in part by activating matrix metalloproteinase-9 (MMP-9), which leads to BBB dysfunction. Therefore, we tested whether betaine affected MMP-9 activity. Interestingly, treatment with betaine significantly inhibited Hcy-induced MMP-9 activity in the frontal cortex but not in the hippocampus after acute Hcy injection. These results suggest that the changes in MMP-9 activity after betaine treatment might have been partially responsible for the amelioration of the memory deficits and that MMP-9 might be a candidate therapeutic target for HHcy.
Lee, Bombi; Sur, Bong-Jun; Han, Jeong-Jun; Shim, Insop; Her, Song; Lee, Yang-Seok; Lee, Hye-Jung; Hahm, Dae-Hyun
Recently, lecithin-derived phosphatidylserine (PS), which originates from marine life, has received much attention as a viable alternative to bovine cerebral cortex PS. In this study, the use of squid phosphatidylcholine-transphosphatidylated PS (SQ-PS) was evaluated through examination of its ameliorating effects on age-associated learning and memory deficits in rats. Aged rats were orally administered SQ-PS (10, 20, or 50 mg/kg per day) once a day for seven days 30 min prior to behavioral assessment in a Morris water maze. SQ-PS administration produced significant dose-dependent improvements in escape latency for finding the platform in the Morris water maze in the aged rats even though Soy-PS administration also exhibited comparable improvements with SQ-PS. Biochemical alterations in the hippocampal cholinergic system, including changes in choline acetyltransferase and acetylcholinesterase immunoreactivity, were consistent with the behavioral results. In addition, SQ-PS treatment significantly restored age-associated decreases of choline transporter and muscarinic acetylcholine receptor type 1 mRNA expression in the hippocampus. These results demonstrate that orally administered SQ-PS dose-dependently aids in the improvement of memory deficits that occur during normal aging in rats. This suggests that SQ-PS may be a useful therapeutic agent in the treatment of diminished memory function in elderly people.
Saitoe, Minoru; Horiuchi, Junjiro; Tamura, Takuya; Ito, Naomi
Understanding the molecular mechanisms underlying age-related memory impairment (AMI) is important not only from a scientific viewpoint but also for the development of therapeutics that may eventually lead to the development of drugs to combat memory loss. AMI has been generally considered to be an overall or nonspecific decay of memory processes that results from dysfunction of neural networks. However, behavioral genetics to test this hypothesis have not been performed previously, due, in part, to the long lifespan of animal models. Using Drosophila, the first extensive behavioral-genetic characterization of AMI has been carried out. In Drosophila, memory acquired after a single olfactory conditioning paradigm has three distinct phases: short-term memory (STM), middle-term memory (MTM), and longer-lasting anesthesia-resistant memory (ARM). Significantly, AMI results from the specific decay of only one memory component, amnesiac-dependent MTM, and not other components. Since amnesiac encodes peptides that enhance adenylyl cyclase activity, these studies suggest the importance of the cAMP signaling pathway in AMI in Drosophila, a finding consistent with several models of AMI in mammals. Although many advances have been made in the study of pathways involved in aging, much remains to be elucidated on how these pathways affect memory formation to cause AMI. Due to its short lifespan, powerful genetics, and well-characterized and conserved pathways involved in memory and lifespan, Drosophila will be a useful model system for studying the molecular mechanisms underlying this process.
Rasch, Björn; Pommer, Julian; Diekelmann, Susanne; Born, Jan
Rapid eye movement (REM) sleep has been considered important for consolidation of memories, particularly of skills. Contrary to expectations, we found that REM sleep suppression by administration of selective serotonin or norepinephrine re-uptake inhibitors after training did not impair consolidation of skills or word-pairs in healthy men but rather enhanced gains in finger tapping accuracy together with sleep spindles. Our results indicate that REM sleep as a unitary phenomenon is not required for skill-memory consolidation.
Burke, Hanna M; Robinson, Cristina M; Wentz, Bethany; McKay, Jerel; Dexter, Kyle W; Pisansky, Julia M; Talbot, Jeffery N; Zoladz, Phillip R
It has been suggested that cognitive impairments exhibited by people with post-traumatic stress disorder (PTSD) result from intrusive, flashback memories transiently interfering with ongoing cognitive processing. Researchers have further speculated that females are more susceptible to developing PTSD because they form stronger traumatic memories than males, hence females may be more sensitive to the negative effects of intrusive memories on cognition. We have examined how the reminder of a naturalistic stress experience would affect rat spatial memory and if sex was a contributing factor to such effects. Male and female Sprague-Dawley rats were exposed, without contact, to an adult female cat for 30 min. Five weeks later, the rats were trained to locate a hidden platform in the radial-arm water maze and given a single long-term memory test trial 24 h later. Before long-term memory testing, the rats were given a 30-min reminder of the cat exposure experienced 5 weeks earlier. The results indicated that the stress reminder impaired spatial memory in the female rats only. Control manipulations revealed that this effect was not attributable to the original cat exposure adversely impacting learning that occurred 5 weeks later, or to merely exposing rats to a novel environment or predator-related cues immediately before testing. These findings provide evidence that the reminder of a naturalistic stressful experience can impair cognitive processing in rats; moreover, since female rats were more susceptible to the memory-impairing effects of the stress reminder, the findings could lend insight into the existing sex differences in susceptibility to PTSD.
Calev, Hila; Spampinato, Lisa M; Press, Valerie G; Meltzer, David O; Arora, Vineet M
Background Effective inpatient teaching requires intact patient memory, but studies suggest hospitalized adults may have memory deficits. Sleep loss among inpatients could contribute to memory impairment. Objective To assess memory in older hospitalized adults, and to test the association between sleep quantity, sleep quality and memory, in order to identify a possible contributor to memory deficits in these patients. Design Prospective cohort study Setting General medicine and hematology/oncology inpatient wards Patients 59 hospitalized adults at least 50 years of age with no diagnosed sleep disorder. Measurements Immediate memory and memory after a 24-hour delay were assessed using a word recall and word recognition task from the University of Southern California Repeatable Episodic Memory Test (USC-REMT). A vignette-based memory task was piloted as an alternative test more closely resembling discharge instructions. Sleep duration and efficiency overnight in the hospital were measured using actigraphy. Results Mean immediate recall was 3.8 words out of 15 (SD=2.1). Forty-nine percent of subjects had poor memory, defined as immediate recall score of 3 or lower. Median immediate recognition was 11 words out of 15 (IQR=9, 13). Median delayed recall score was 1 word and median delayed recognition was 10 words (IQR= 8–12). In-hospital sleep duration and efficiency were not significantly associated with memory. The medical vignette score was correlated with immediate recall (r=0.49, p<0.01) Conclusions About half of inpatients studied had poor memory while in the hospital, signaling that hospitalization might not be an ideal teachable moment. In-hospital sleep was not associated with memory scores. PMID:25872763
Salgado-Puga, Karla; Prado-Alcalá, Roberto A.; Peña-Ortega, Fernando
Alzheimer's disease (AD) is associated with an early hippocampal dysfunction, which is likely induced by an increase in soluble amyloid beta peptide (Aβ). This hippocampal failure contributes to the initial memory deficits observed both in patients and in AD animal models and possibly to the deterioration in activities of daily living (ADL). One typical rodent behavior that has been proposed as a hippocampus-dependent assessment model of ADL in mice and rats is burrowing. Despite the fact that AD transgenic mice show some evidence of reduced burrowing, it has not been yet determined whether or not Aβ can affect this typical rodent behavior and whether this alteration correlates with the well-known Aβ-induced memory impairment. Thus, the purpose of this study was to test whether or not Aβ affects burrowing while inducing hippocampus-dependent memory impairment. Surprisingly, our results show that intrahippocampal application of Aβ increases burrowing while inducing memory impairment. We consider that this Aβ-induced increase in burrowing might be associated with a mild anxiety state, which was revealed by increased freezing behavior in the open field, and conclude that Aβ-induced hippocampal dysfunction is reflected in the impairment of ADL and memory, through mechanisms yet to be determined. PMID:26229236
Pachauri, Shakti D; Verma, Priya Ranjan P; Dwivedi, Anil K; Tota, Santoshkumar; Khandelwal, Kiran; Saxena, Jitendra K; Nath, Chandishwar
This study evaluated the effects of a standardized ethyl acetate extract of Morinda citrifolia L. (Noni) fruit on impairment of memory, brain energy metabolism, and cholinergic function in intracerebral streptozotocin (STZ)-treated mice. STZ (0.5 mg/kg) was administered twice at an interval of 48 h. Noni (50 and 100 mg/kg, postoperatively) was administered for 21 days following STZ administration. Memory function was evaluated using Morris Water Maze and passive avoidance tests, and brain levels of cholinergic function, oxidative stress, energy metabolism, and brain-derived neurotrophic factor (BDNF) were estimated. STZ caused memory impairment in Morris Water Maze and passive avoidance tests along with reduced brain levels of ATP, BDNF, and acetylcholine and increased acetylcholinesterase activity and oxidative stress. Treatment with Noni extract (100 mg/kg) prevented the STZ-induced memory impairment in both behavioral tests along with reduced oxidative stress and acetylcholinesterase activity, and increased brain levels of BDNF, acetylcholine, and ATP level. The study shows the beneficial effects of Noni fruit against STZ-induced memory impairment, which may be attributed to improved brain energy metabolism, cholinergic neurotransmission, BDNF, and antioxidative action.
Birnbaum, S. G.; Yuan, P. X.; Wang, M.; Vijayraghavan, S.; Bloom, A. K.; Davis, D. J.; Gobeske, K. T.; Sweatt, J. D.; Manji, H. K.; Arnsten, A. F. T.
The prefrontal cortex is a higher brain region that regulates thought, behavior, and emotion using representational knowledge, operations often referred to as working memory. We tested the influence of protein kinase C (PKC) intracellular signaling on prefrontal cortical cognitive function and showed that high levels of PKC activity in prefrontal cortex, as seen for example during stress exposure, markedly impair behavioral and electrophysiological measures of working memory. These data suggest that excessive PKC activation can disrupt prefrontal cortical regulation of behavior and thought, possibly contributing to signs of prefrontal cortical dysfunction such as distractibility, impaired judgment, impulsivity, and thought disorder.
Wang, Qing M.; Meng, Zhaoxiang; Yin, Zhenglu
Objective To investigate whether gait dysfunction is a predictor of severe spatial learning and memory impairment in aged mice. Methods A total of 100 12-month-old male mice that had no obvious abnormal motor ability and whose Morris water maze performances were not significantly different from those of two-month-old male mice were selected for the study. The selected aged mice were then divided into abnormal or normal gait groups according to the results from the quantitative gait assessment. Gaits of aged mice were defined as abnormal when the values of quantitative gait parameters were two standard deviations (SD) lower or higher than those of 2-month-old male mice. Gait parameters included stride length, variability of stride length, base of support, cadence, and average speed. After nine months, mice exhibiting severe spatial learning and memory impairment were separated from mice with mild or no cognitive dysfunction. The rate of severe spatial learning and memory impairment in the abnormal and normal gait groups was tested by a chi-square test and the correlation between gait dysfunction and decline in cognitive function was tested using a diagnostic test. Results The 12-month-old aged mice were divided into a normal gait group (n = 75) and an abnormal gait group (n = 25). Nine months later, three mice in the normal gait group and two mice in the abnormal gait group had died. The remaining mice were subjected to the Morris water maze again, and 17 out of 23 mice in the abnormal gait group had developed severe spatial learning and memory impairment, including six with stride length deficits, 15 with coefficient of variation (CV) in stride length, two with base of support (BOS) deficits, five with cadence dysfunction, and six with average speed deficits. In contrast, only 15 out of 72 mice in the normal gait group developed severe spatial learning and memory impairment. The rate of severe spatial learning and memory impairment was significantly higher in
Rogers, Timothy T.; Graham, Kim S.; Patterson, Karalyn
To investigate how basic aspects of perception are shaped by acquired knowledge about the world, we assessed colour perception and cognition in patients with semantic dementia (SD), a disorder that progressively erodes conceptual knowledge. We observed a previously undocumented pattern of impairment to colour perception and cognition characterized by: (i) a normal ability to discriminate between only subtly different colours but an impaired ability to group different colours into categories, (ii) normal perception and memory for the colours red, green, and blue but impaired perception and memory for colours lying between these regions of a fully-saturated and luminant spectrum, and (iii) normal naming of polar colours in the opponent-process colour system (red, green, blue, yellow, white, and black) but impaired naming of other basic colours (brown, gray, pink, and orange). The results suggest that fundamental aspects of perception can be shaped by acquired knowledge about the world, but only within limits. PMID:25637227
Dzieciol, Anna M.; Gadian, David G.; Jentschke, Sebastian; Doeller, Christian F.; Burgess, Neil; Mishkin, Mortimer
The extent to which navigational spatial memory depends on hippocampal integrity in humans is not well documented. We investigated allocentric spatial recall using a virtual environment in a group of patients with severe hippocampal damage (SHD), a group of patients with “moderate” hippocampal damage (MHD), and a normal control group. Through four learning blocks with feedback, participants learned the target locations of four different objects in a circular arena. Distal cues were present throughout the experiment to provide orientation. A circular boundary as well as an intra-arena landmark provided spatial reference frames. During a subsequent test phase, recall of all four objects was tested with only the boundary or the landmark being present. Patients with SHD were impaired in both phases of this task. Across groups, performance on both types of spatial recall was highly correlated with memory quotient (MQ), but not with intelligence quotient (IQ), age, or sex. However, both measures of spatial recall separated experimental groups beyond what would be expected based on MQ, a widely used measure of general memory function. Boundary-based and landmark-based spatial recall were both strongly related to bilateral hippocampal volumes, but not to volumes of the thalamus, putamen, pallidum, nucleus accumbens, or caudate nucleus. The results show that boundary-based and landmark-based allocentric spatial recall are similarly impaired in patients with SHD, that both types of recall are impaired beyond that predicted by MQ, and that recall deficits are best explained by a reduction in bilateral hippocampal volumes. SIGNIFICANCE STATEMENT In humans, bilateral hippocampal atrophy can lead to profound impairments in episodic memory. Across species, perhaps the most well-established contribution of the hippocampus to memory is not to episodic memory generally but to allocentric spatial memory. However, the extent to which navigational spatial memory depends on
Mhaidat, Nizar M; Alzoubi, Karem H; Khabour, Omar F; Tashtoush, Noor H; Banihani, Saleem A; Abdul-razzak, Khalid K
In the current study, the possible beneficial effect of vitamin C (VitC) against sleep deprivation induced memory impairment was examined. Chronic sleep deprivation was induced via placing rats in a modified multiple platform apparatus for 8h/day for a period of 6 weeks. Concomitantly, VitC was administered to animals at doses of 150 and 500 mg/kg/day. After 6 weeks of treatment, the radial arm water maze (RAWM) was used to test for spatial learning and memory performance. Moreover, the hippocampus was dissected; and levels/activities of antioxidant defense biomarkers glutathione reduced (GSH), glutathione oxidized (GSSG), GSH/GSSG ratio, catalase, superoxide dismutase (SOD), and thiobarbituric acid reactive substances (TBARS), were evaluated. Results revealed that chronic sleep deprivation impaired short- and long-term memories (P<0.05). This impairment was prevented by chronic VitC treatments. In addition, VitC normalized sleep deprivation induced decreases in hippocamppal GSH/GSSG ratio (P<0.05), and activities of catalase, and SOD, and increase in GSSG levels (P<0.05). Collectively, spatial memory impairment was induced by chronic sleep deprivation, and VitC treatment prevented such impairment. This was possibly achieved via normalizing antioxidant defense mechanisms of the hippocampus.
Lum, Jarrad A. G.; Conti-Ramsden, Gina
This review examined the status of long-term memory systems in specific language impairment (SLI)--declarative memory and aspects of procedural memory in particular. Studies included in the review were identified following a systematic search of the literature and findings combined using meta-analysis. This review showed that individuals with SLI…
Mitchell, Anna S.; Dalrymple-Alford, John C.
Damage to the medial region of the thalamus, both in clinical cases (e.g., patients with infarcts or the Korsakoff's syndrome) and animal lesion models, is associated with variable amnesic deficits. Some studies suggest that many of these memory deficits rely on the presence of lateral thalamic lesions (LT) that include the intralaminar nuclei,…
Gutierrez, Ranier; De la Cruz, Vanesa; Rodriguez-Ortiz, Carlos J.; Bermudez-Rattoni, Federico
The relevance of perirhinal cortical cholinergic and glutamatergic neurotransmission for taste recognition memory and learned taste aversion was assessed by microinfusions of muscarinic (scopolamine), NMDA (AP-5), and AMPA (NBQX) receptor antagonists. Infusions of scopolamine, but not AP5 or NBQX, prevented the consolidation of taste recognition…
Popp, Earl Y.; Serra, Michael J.
Recent research suggests that human memory systems evolved to remember animate things better than inanimate things. In the present experiments, we examined whether these effects occur for both free recall and cued recall. In Experiment 1, we directly compared the effect of animacy on free recall and cued recall. Participants studied lists of…
Majerus, Steve; Attout, Lucie; Artielle, Marie-Amélie; Van der Kaa, Marie-Anne
Verbal short-term memory (STM) impairment represents a frequent and long-lasting deficit in aphasia, and it will prevent patients from recovering fully functional language abilities. The aim of this study was to obtain a more precise understanding of the nature of verbal STM impairment in aphasia, by determining whether verbal STM impairment is merely a consequence of underlying language impairment, as suggested by linguistic accounts of verbal STM, or whether verbal STM impairment reflects an additional, specific deficit. We investigated this question by contrasting item-based STM measures, supposed to depend strongly upon language activation, and order-based STM measures, supposed to reflect the operation of specific, serial order maintenance mechanisms, in a sample of patients with single-word processing deficits at the phonological and/or lexical level. A group-level analysis showed robust impairment for both item and serial order STM aspects in the aphasic group relative to an age-matched control group. An analysis of individual profiles revealed an important heterogeneity of verbal STM profiles, with patients presenting either selective item STM deficits, selective order STM deficits, generalized item and serial order STM deficits or no significant STM impairment. Item but not serial order STM impairment correlated with the severity of phonological impairment. These results disconfirm a strong version of the linguistic account of verbal STM impairment in aphasia, by showing variable impairment to both item and serial order processing aspects of verbal STM.
Teather, Lisa A; Wurtman, Richard J
We previously showed that dietary cytidine (5')-diphosphocholine (CDP-choline) supplementation could protect against the development of memory deficits in aging rats. In the present study, younger rats exposed to impoverished environmental conditions and manifesting hippocampal-dependent memory impairments similar to those observed in the aging rodents were given CDP-choline, and its effects on this cognitive deficit were assessed. Male Sprague-Dawley rats reared for 3 mo in impoverished (IC) or enriched environmental (EC) conditions concurrently received either a control diet or a diet supplemented with CDP-choline (approximately 500 mg/kg/d). After 3 mo, rats were trained to perform spatial and cued versions of the Morris water maze, and their rates of acquisition and retention were compared. Impoverished rats exhibited a selective deficit in hippocampal-dependent spatial memory which could be ameliorated by feeding them CDP-choline. The CDP-choline had no memory-enhancing effect in enriched rats, nor did it prevent the memory impairment of impoverished rats if the animals consumed it for the initial or final months instead of for the entire 3-mo period. These findings indicate that long-term dietary CDP-choline supplementation can ameliorate the hippocampal-dependent memory impairment caused by impoverished environmental conditions in rats, and suggest that its actions result, in part, from a long-term effect such as enhanced membrane phosphatide synthesis, an effect shown to require long-term dietary supplementation with CDP-choline.
Teather, Lisa A.; Wurtman, Richard J.
We previously showed that dietary cytidine (5′)-diphosphocholine (CDP-choline) supplementation could protect against the development of memory deficits in aging rats. In the present study, younger rats exposed to impoverished environmental conditions and manifesting hippocampal-dependent memory impairments similar to those observed in the aging rodents were given CDP-choline, and its effects on this cognitive deficit were assessed. Male Sprague-Dawley rats reared for 3 mo in impoverished (IC) or enriched environmental (EC) conditions concurrently received either a control diet or a diet supplemented with CDP-choline (∼500 mg/kg/d). After 3 mo, rats were trained to perform spatial and cued versions of the Morris water maze, and their rates of acquisition and retention were compared. Impoverished rats exhibited a selective deficit in hippocampal-dependent spatial memory which could be ameliorated by feeding them CDP-choline. The CDP-choline had no memory-enhancing effect in enriched rats, nor did it prevent the memory impairment of impoverished rats if the animals consumed it for the initial or final months instead of for the entire 3-mo period. These findings indicate that long-term dietary CDP-choline supplementation can ameliorate the hippocampal-dependent memory impairment caused by impoverished environmental conditions in rats, and suggest that its actions result, in part, from a long-term effect such as enhanced membrane phosphatide synthesis, an effect shown to require long-term dietary supplementation with CDP-choline. PMID:15647594
Cha, Hye Jin; Kim, Yun Ji; Jeon, Seo Young; Kim, Young-Hoon; Shin, Jisoon; Yun, Jaesuk; Han, Kyoungmoon; Park, Hye-Kyung; Kim, Hyung Soo
Although alkyl nitrites are used as recreational drugs, there is only little research data regarding their effects on the central nervous system including their neurotoxicity. This study investigated the neurotoxicity of three representative alkyl nitrites (isobutyl nitrite, isoamyl nitrite, and butyl nitrite), and whether it affected learning/memory function and motor coordination in rodents. Morris water maze test was performed in mice after administrating the mice with varying doses of the substances in two different injection schedules of memory acquisition and memory retention. A rota-rod test was then performed in rats. All tested alkyl nitrites lowered the rodents' capacity for learning and memory, as assessed by both the acquisition and retention tests. The results of the rota-rod test showed that isobutyl nitrite in particular impaired motor coordination in chronically treated rats. The mice chronically injected with isoamyl nitrite also showed impaired function, while butyl nitrite had no significant effect. The results of the water maze test suggest that alkyl nitrites may impair learning and memory. Additionally, isoamyl nitrite affected the rodents' motor coordination ability. Collectively, our findings suggest that alkyl nitrites may induce neurotoxicity, especially on the aspect of learning and memory function.
Wardell, Jeffrey D.; Quilty, Lena C.; Hendershot, Christian S.
Impaired control over alcohol is an important risk factor for heavy drinking among young adults and may mediate, in part, the association between personality risk and alcohol problems. Research suggests that trait impulsivity is associated with impaired control over alcohol; however, few studies of this association have included a range of impulsivity facets. The purpose of this study was to examine specific pathways from higher-order impulsivity factors to alcohol problems mediated via impaired control over alcohol. We also examined the moderating role of working memory in these associations. Young heavy drinkers (N=300) completed two multidimensional impulsivity measures (UPPS-P and BIS-11) along with self-report measures of impaired control over alcohol, alcohol use, and alcohol problems. Working memory was assessed using a computerized digit span task. Results showed that the impulsivity facets loaded onto two higher-order factors that were labeled response and reflection impulsivity. Response impulsivity predicted unique variance in self-reported impaired control and alcohol problems, whereas reflection impulsivity predicted unique variance in heavy drinking frequency only. Further, significant indirect associations were observed from response and reflection impulsivity to alcohol problems mediated via impaired control and heavy drinking frequency, respectively. Working memory and sensation seeking were not uniquely associated with the alcohol variables, and no support was found for the moderating role of working memory. The results help to clarify associations among impulsivity, impaired control, and alcohol problems, suggesting that impaired control may play a specific role in the pathway to alcohol problems from response impulsivity but not from reflection impulsivity. PMID:27269291
Bañuelos, Cristina; Beas, B Sofia; McQuail, Joseph A; Gilbert, Ryan J; Frazier, Charles J; Setlow, Barry; Bizon, Jennifer L
Working memory functions supported by the prefrontal cortex decline in normal aging. Disruption of corticolimbic GABAergic inhibitory circuits can impair working memory in young subjects; however, relatively little is known regarding how aging impacts prefrontal cortical GABAergic signaling and whether such changes contribute to cognitive deficits. The current study used a rat model to evaluate the effects of aging on expression of prefrontal GABAergic synaptic proteins in relation to working memory decline, and to test whether pharmacological manipulations of prefrontal GABAergic signaling can improve working memory abilities in aged subjects. Results indicate that in aged medial prefrontal cortex (mPFC), expression of the vesicular GABA transporter VGAT was unchanged; however, there was a significant increase in expression of the GABA synthesizing enzyme GAD67, and a significant decrease in the primary neuronal GABA transporter GAT-1 and in both subunits of the GABA(B) receptor (GABA(B)R). Expression of VGAT, GAD67, and GAT-1 was not associated with working memory ability. In contrast, among aged rats, GABA(B)R expression was significantly and negatively associated with working memory performance, such that lower GABA(B)R expression predicted better working memory. Subsequent experiments showed that systemic administration of a GABA(B)R antagonist, CGP55845, dose-dependently enhanced working memory in aged rats. This enhancing effect of systemic CGP55845 was reproduced by direct intra-mPFC administration. Together, these data suggest that age-related dysregulation of GABAergic signaling in prefrontal cortex may play a causal role in impaired working memory and that targeting GABA(B)Rs may provide therapeutic benefit for age-related impairments in executive functions.
Bañuelos, Cristina; Beas, B. Sofia; McQuail, Joseph A.; Gilbert, Ryan J.; Frazier, Charles J.; Setlow, Barry
Working memory functions supported by the prefrontal cortex decline in normal aging. Disruption of corticolimbic GABAergic inhibitory circuits can impair working memory in young subjects; however, relatively little is known regarding how aging impacts prefrontal cortical GABAergic signaling and whether such changes contribute to cognitive deficits. The current study used a rat model to evaluate the effects of aging on expression of prefrontal GABAergic synaptic proteins in relation to working memory decline, and to test whether pharmacological manipulations of prefrontal GABAergic signaling can improve working memory abilities in aged subjects. Results indicate that in aged medial prefrontal cortex (mPFC), expression of the vesicular GABA transporter VGAT was unchanged; however, there was a significant increase in expression of the GABA synthesizing enzyme GAD67, and a significant decrease in the primary neuronal GABA transporter GAT-1 and in both subunits of the GABA(B) receptor (GABA(B)R). Expression of VGAT, GAD67, and GAT-1 was not associated with working memory ability. In contrast, among aged rats, GABA(B)R expression was significantly and negatively associated with working memory performance, such that lower GABA(B)R expression predicted better working memory. Subsequent experiments showed that systemic administration of a GABA(B)R antagonist, CGP55845, dose-dependently enhanced working memory in aged rats. This enhancing effect of systemic CGP55845 was reproduced by direct intra-mPFC administration. Together, these data suggest that age-related dysregulation of GABAergic signaling in prefrontal cortex may play a causal role in impaired working memory and that targeting GABA(B)Rs may provide therapeutic benefit for age-related impairments in executive functions. PMID:24599447
Salvato, Gerardo; Patai, Eva Z.; Nobre, Anna C.
It is increasingly recognised that spatial contextual long-term memory (LTM) prepares neural activity for guiding visuo-spatial attention in a proactive manner. In the current study, we investigated whether the decline in explicit memory observed in healthy ageing would compromise this mechanism. We compared the behavioural performance of younger and older participants on learning new contextual memories, on orienting visual attention based on these learnt contextual associations, and on explicit recall of contextual memories. We found a striking dissociation between older versus younger participants in the relationship between the ability to retrieve contextual memories versus the ability to use these to guide attention to enhance performance on a target-detection task. Older participants showed significant deficits in the explicit retrieval task, but their behavioural benefits from memory-based orienting of attention were equivalent to those in young participants. Furthermore, memory-based orienting correlated significantly with explicit contextual LTM in younger adults but not in older adults. These results suggest that explicit memory deficits in ageing might not compromise initial perception and encoding of events. Importantly, the results also shed light on the mechanisms of memory-guided attention, suggesting that explicit contextual memories are not necessary. PMID:26649914
Salvato, Gerardo; Patai, Eva Z; Nobre, Anna C
It is increasingly recognised that spatial contextual long-term memory (LTM) prepares neural activity for guiding visuo-spatial attention in a proactive manner. In the current study, we investigated whether the decline in explicit memory observed in healthy ageing would compromise this mechanism. We compared the behavioural performance of younger and older participants on learning new contextual memories, on orienting visual attention based on these learnt contextual associations, and on explicit recall of contextual memories. We found a striking dissociation between older versus younger participants in the relationship between the ability to retrieve contextual memories versus the ability to use these to guide attention to enhance performance on a target-detection task. Older participants showed significant deficits in the explicit retrieval task, but their behavioural benefits from memory-based orienting of attention were equivalent to those in young participants. Furthermore, memory-based orienting correlated significantly with explicit contextual LTM in younger adults but not in older adults. These results suggest that explicit memory deficits in ageing might not compromise initial perception and encoding of events. Importantly, the results also shed light on the mechanisms of memory-guided attention, suggesting that explicit contextual memories are not necessary.
Conti-Ramsden, Gina; Ullman, Michael T.; Lum, Jarrad A. G.
What memory systems underlie grammar in children, and do these differ between typically developing (TD) children and children with specific language impairment (SLI)? Whilst there is substantial evidence linking certain memory deficits to the language problems in children with SLI, few studies have investigated multiple memory systems simultaneously, examining not only possible memory deficits but also memory abilities that may play a compensatory role. This study examined the extent to which procedural, declarative, and working memory abilities predict receptive grammar in 45 primary school aged children with SLI (30 males, 15 females) and 46 TD children (30 males, 16 females), both on average 9;10 years of age. Regression analyses probed measures of all three memory systems simultaneously as potential predictors of receptive grammar. The model was significant, explaining 51.6% of the variance. There was a significant main effect of learning in procedural memory and a significant group × procedural learning interaction. Further investigation of the interaction revealed that procedural learning predicted grammar in TD but not in children with SLI. Indeed, procedural learning was the only predictor of grammar in TD. In contrast, only learning in declarative memory significantly predicted grammar in SLI. Thus, different memory systems are associated with receptive grammar abilities in children with SLI and their TD peers. This study is, to our knowledge, the first to demonstrate a significant group by memory system interaction in predicting grammar in children with SLI and their TD peers. In line with Ullman’s Declarative/Procedural model of language and procedural deficit hypothesis of SLI, variability in understanding sentences of varying grammatical complexity appears to be associated with variability in procedural memory abilities in TD children, but with declarative memory, as an apparent compensatory mechanism, in children with SLI. PMID:26284013
Conti-Ramsden, Gina; Ullman, Michael T; Lum, Jarrad A G
What memory systems underlie grammar in children, and do these differ between typically developing (TD) children and children with specific language impairment (SLI)? Whilst there is substantial evidence linking certain memory deficits to the language problems in children with SLI, few studies have investigated multiple memory systems simultaneously, examining not only possible memory deficits but also memory abilities that may play a compensatory role. This study examined the extent to which procedural, declarative, and working memory abilities predict receptive grammar in 45 primary school aged children with SLI (30 males, 15 females) and 46 TD children (30 males, 16 females), both on average 9;10 years of age. Regression analyses probed measures of all three memory systems simultaneously as potential predictors of receptive grammar. The model was significant, explaining 51.6% of the variance. There was a significant main effect of learning in procedural memory and a significant group × procedural learning interaction. Further investigation of the interaction revealed that procedural learning predicted grammar in TD but not in children with SLI. Indeed, procedural learning was the only predictor of grammar in TD. In contrast, only learning in declarative memory significantly predicted grammar in SLI. Thus, different memory systems are associated with receptive grammar abilities in children with SLI and their TD peers. This study is, to our knowledge, the first to demonstrate a significant group by memory system interaction in predicting grammar in children with SLI and their TD peers. In line with Ullman's Declarative/Procedural model of language and procedural deficit hypothesis of SLI, variability in understanding sentences of varying grammatical complexity appears to be associated with variability in procedural memory abilities in TD children, but with declarative memory, as an apparent compensatory mechanism, in children with SLI.
Archibald, Lisa M. D.; Gathercole, Susan E.
Background: Investigations of the cognitive processes underlying specific language impairment (SLI) have implicated deficits in the storage and processing of phonological information, but to date these abilities have not been studied in the same group of children with SLI. Aims: To examine the extent to which deficits in immediate verbal…
Morgan, Celia J. A.; Dodds, Chris M.; Furby, Hannah; Pepper, Fiona; Fam, Johnson; Freeman, Tom P.; Hughes, Emer; Doeller, Christian; King, John; Howes, Oliver; Stone, James M.
Ketamine, a non-competitive N-methyl-d-aspartate receptor antagonist, is rising in popularity as a drug of abuse. Preliminary evidence suggests that chronic, heavy ketamine use may have profound effects on spatial memory but the mechanism of these deficits is as yet unclear. This study aimed to examine the neural mechanism by which heavy ketamine use impairs spatial memory processing. In a sample of 11 frequent ketamine users and 15 poly-drug controls, matched for IQ, age, years in education. We used fMRI utilizing an ROI approach to examine the neural activity of three regions known to support successful navigation; the hippocampus, parahippocampal gyrus, and the caudate nucleus during a virtual reality task of spatial memory. Frequent ketamine users displayed spatial memory deficits, accompanied by and related to, reduced activation in both the right hippocampus and left parahippocampal gyrus during navigation from memory, and in the left caudate during memory updating, compared to controls. Ketamine users also exhibited schizotypal and dissociative symptoms that were related to hippocampal activation. Impairments in spatial memory observed in ketamine users are related to changes in medial temporal lobe activation. Disrupted medial temporal lobe function may be a consequence of chronic ketamine abuse and may relate to schizophrenia-like symptomatology observed in ketamine users. PMID:25538631
Spanoudis, George C; Natsopoulos, Demetrios
Memory and language operate in synergy. Recent literature stresses the importance of memory functioning in interpreting language deficits. Two groups of 50 children each, ages 8-12 were studied. The first group included children with specific language impairment, while the participants in the second group were typically developing children. The two groups, which were matched on age, nonverbal intelligence and varied significantly in verbal ability were examined, using a test battery of four memory functioning (phonological, working and long-term memory) and five mental verb measures. The statistical analyses indicated that the two groups differed significantly in all language and memory measures; a logistic regression analysis revealed that within each main group existed nested subgroups of different developmental patterns with working and long-term memory measures as the most robust discriminate markers of classification. Language impaired children had more difficulties in the acquisition of mental verbs because they are less able to process and store phonological information in working memory and long-term lexicon.
Pearson-Leary, Jiah; Osborne, Danielle Maria; McNay, Ewan C.
Both acute and chronic stress profoundly affect hippocampally-dependent learning and memory: moderate stress generally enhances, while chronic or extreme stress can impair, neural and cognitive processes. Within the brain, stress elevates both norepinephrine and glucocorticoids, and both affect several genomic and signaling cascades responsible for modulating memory strength. Memories formed at times of stress can be extremely strong, yet stress can also impair memory to the point of amnesia. Often overlooked in consideration of the impact of stress on cognitive processes, and specifically memory, is the important contribution of glia as a target for stress-induced changes. Astrocytes, microglia, and oligodendrocytes all have unique contributions to learning and memory. Furthermore, these three types of glia express receptors for both norepinephrine and glucocorticoids and are hence immediate targets of stress hormone actions. It is becoming increasingly clear that inflammatory cytokines and immunomodulatory molecules released by glia during stress may promote many of the behavioral effects of acute and chronic stress. In this review, the role of traditional genomic and rapid hormonal mechanisms working in concert with glia to affect stress-induced learning and memory will be emphasized. PMID:26793072
Machado, M L; Lelong-Boulouard, V; Smith, P F; Freret, T; Philoxene, B; Denise, P; Besnard, S
It is now well established that vestibular information plays an important role in spatial memory processes. Although vestibular lesions induce anxiety in humans, this finding remains controversial in rodents. However, it is possible that anxiety-related behavior is associated with spatial memory impairments after vestibular lesions. We aimed to evaluate anxiety-like behavior and the effect of an anxiolytic treatment during a complex spatial memory task in a rat model of compensated bilateral vestibular lesions. Adult rats were divided into four groups, with or without vestibular lesions and, treated or untreated by diazepam. The vestibular lesion was performed by transtympanic injection of arsanilate and compared to transtympanic saline injection. Diazepam or saline was administered 1h before each test or learning session. Vestibular-lesioned rats exhibited anxiety-like behavior which was decreased with diazepam. Spatial memory performance was similar in control-treated and untreated groups, suggesting no effect on memory at the dose of diazepam used. Spatial memory performances were not modified by anxiolytic drug treatment in vestibular-lesioned rats compared to vestibular-lesioned rats without drug treatment. We conclude that bilateral vestibular lesions in rats induced anxiety-like behavior which was unrelated to spatial memory impairment and was probably specifically related to the loss of vestibular information.
Crawford, Trevor J; Higham, Steve
Dementia (most notably, Alzheimer's Disease) is often associated with impairments of both working memory and inhibitory control. However, it is unclear whether these are functionally distinct impairments. We addressed the issue of whether working memory and inhibitory control can be dissociated, using data from a sample of patients who were recruited in a longitudinal study (Crawford et al., 2013, 2015). The first case revealed a preserved working memory capacity together with poor inhibitory control in the anti-saccade task. A longitudinal follow-up revealed that the defective inhibitory control emerged 12-months before the dementia was evident on the mini-mental state examination assessment. A second case revealed a poor working memory together with a well-preserved level of inhibitory control. The dissociation of working memory and inhibitory control was confirmed statistically in 7 additional cases. These findings yield converging evidence that working memory and inhibitory control are distinct cognitive operations and challenges the Kimberg and Farah (2000) cognitive model of working memory.
Pearson-Leary, Jiah; Osborne, Danielle Maria; McNay, Ewan C
Both acute and chronic stress profoundly affect hippocampally-dependent learning and memory: moderate stress generally enhances, while chronic or extreme stress can impair, neural and cognitive processes. Within the brain, stress elevates both norepinephrine and glucocorticoids, and both affect several genomic and signaling cascades responsible for modulating memory strength. Memories formed at times of stress can be extremely strong, yet stress can also impair memory to the point of amnesia. Often overlooked in consideration of the impact of stress on cognitive processes, and specifically memory, is the important contribution of glia as a target for stress-induced changes. Astrocytes, microglia, and oligodendrocytes all have unique contributions to learning and memory. Furthermore, these three types of glia express receptors for both norepinephrine and glucocorticoids and are hence immediate targets of stress hormone actions. It is becoming increasingly clear that inflammatory cytokines and immunomodulatory molecules released by glia during stress may promote many of the behavioral effects of acute and chronic stress. In this review, the role of traditional genomic and rapid hormonal mechanisms working in concert with glia to affect stress-induced learning and memory will be emphasized.
Chen, Yuncai; Molet, Jenny; Lauterborn, Julie C; Trieu, Brian H; Bolton, Jessica L; Patterson, Katelin P; Gall, Christine M; Lynch, Gary; Baram, Tallie Z
Stress influences memory, an adaptive process crucial for survival. During stress, hippocampal synapses are bathed in a mixture of stress-released molecules, yet it is unknown whether or how these interact to mediate the effects of stress on memory. Here, we demonstrate novel synergistic actions of corticosterone and corticotropin-releasing hormone (CRH) on synaptic physiology and dendritic spine structure that mediate the profound effects of acute concurrent stresses on memory. Spatial memory in mice was impaired enduringly after acute concurrent stresses resulting from loss of synaptic potentiation associated with disrupted structure of synapse-bearing dendritic spines. Combined application of the stress hormones corticosterone and CRH recapitulated the physiological and structural defects provoked by acute stresses. Mechanistically, corticosterone and CRH, via their cognate receptors, acted synergistically on the spine-actin regulator RhoA, promoting its deactivation and degradation, respectively, and destabilizing spines. Accordingly, blocking the receptors of both hormones, but not each alone, rescued memory. Therefore, the synergistic actions of corticosterone and CRH at hippocampal synapses underlie memory impairments after concurrent and perhaps also single, severe acute stresses, with potential implications to spatial memory dysfunction in, for example, posttraumatic stress disorder.
Morris, Ken A; Chang, Qing; Mohler, Eric G; Gold, Paul E
Increases in blood glucose levels are an important component of the mechanisms by which epinephrine enhances memory formation. The present experiments addressed the hypothesis that a dysfunction in the blood glucose response to circulating epinephrine contributes to age-related memory impairments. Doses of epinephrine and glucagon that significantly increased blood glucose levels in young adult rats were far less effective at doing so in 2-year-old rats. In young rats, epinephrine and glucose were about equally effective in enhancing memory and in prolonging post-training release of acetylcholine in the hippocampus. However, glucose was more effective than epinephrine in enhancing both memory and acetylcholine release in aged rats. These results suggest that an uncoupling between circulating epinephrine and glucose levels in old rats may lead to an age-related reduction in the provision of glucose to the brain during training. This in turn may contribute to age-related changes in memory and neural plasticity.
Costa, Alberto; Monaco, Marco; Zabberoni, Silvia; Peppe, Antonella; Perri, Roberta; Fadda, Lucia; Iannarelli, Francesca; Caltagirone, Carlo; Carlesimo, Giovanni A.
The hypothesis has been advanced that memory disorders in individuals with Parkinson’s disease (PD) are related to either retrieval or consolidation failure. However, the characteristics of the memory impairments of PD patients with amnestic mild cognitive impairment have not been clarified. This study was aimed at investigating whether memory deficits in PD patients with amnestic mild cognitive impairment (PDaMCI) are due to failure of retrieval or consolidation processes. Sixteen individuals with PDaMCI, 20 with amnestic mild cognitive impairment without PD (aMCINPD), and 20 healthy controls were recruited. Participants were administered the Free and Cued Selective Reminding Test. An index of cueing was computed for each subject to capture the advantage in retrieval of cued compared to free recall. Individuals with PDaMCI performed worse than healthy controls on the free recall (p<0.01) but not the cued recall (p>0.10) task, and they performed better than aMCINPD subjects on both recall measures (p<0.01). The index of cueing of subjects with PD was comparable to that of healthy controls (p>0.10) but it was significantly higher than that of the aMCINPD sample (p<0.01). Moreover, PD patients’ performance on free recall trials was significantly predicted by scores on a test investigating executive functions (i.e., the Modified Card Sorting Test; p = 0.042). Findings of the study document that, in subjects with amnestic mild cognitive impairment associated to PD, episodic memory impairment is related to retrieval rather than to consolidation failure. The same data suggest that, in these individuals, memory deficits might be due to altered frontal-related executive functioning. PMID:24465977
Carrasquillo, Minerva M; Crook, Julia E; Pedraza, Otto; Thomas, Colleen S; Pankratz, V Shane; Allen, Mariet; Nguyen, Thuy; Malphrus, Kimberly G; Ma, Li; Bisceglio, Gina D; Roberts, Rosebud O; Lucas, John A; Smith, Glenn E; Ivnik, Robert J; Machulda, Mary M; Graff-Radford, Neill R; Petersen, Ronald C; Younkin, Steven G; Ertekin-Taner, Nilüfer
We tested association of nine late-onset Alzheimer's disease (LOAD) risk variants from genome-wide association studies (GWAS) with memory and progression to mild cognitive impairment (MCI) or LOAD (MCI/LOAD) in older Caucasians, cognitively normal at baseline and longitudinally evaluated at Mayo Clinic Rochester and Jacksonville (n>2000). Each variant was tested both individually and collectively using a weighted risk score. APOE-e4 associated with worse baseline memory and increased decline with highly significant overall effect on memory. CLU-rs11136000-G associated with worse baseline memory and incident MCI/LOAD. MS4A6A-rs610932-C associated with increased incident MCI/LOAD and suggestively with lower baseline memory. ABCA7-rs3764650-C and EPHA1-rs11767557-A associated with increased rates of memory decline in subjects with a final diagnosis of MCI/LOAD. PICALM-rs3851179-G had an unexpected protective effect on incident MCI/LOAD. Only APOE-inclusive risk scores associated with worse memory and incident MCI/LOAD. The collective influence of the nine top LOAD GWAS variants on memory decline and progression to MCI/LOAD appears limited. Discovery of biologically functional variants at these loci may uncover stronger effects on memory and incident disease.
Payne, Jessica D; Jackson, Eric D; Hoscheidt, Siobhan; Ryan, Lee; Jacobs, W Jake; Nadel, Lynn
Stressful events frequently comprise both neutral and emotionally arousing information, yet the impact of stress on emotional and neutral events is still not fully understood. The hippocampus and frontal cortex have dense concentrations of receptors for stress hormones, such as cortisol, which at high levels can impair performance on hippocampally dependent memory tasks. Yet, the same stress hormones can facilitate memory for emotional information, which involves interactions between the hippocampus and amygdala. Here, we induced psychosocial stress prior to encoding and examined its long-term effects on memory for emotional and neutral episodes. The stress manipulation disrupted long-term memory for a neutral episode, but facilitated long-term memory for an equivalent emotional episode compared with a control condition. The stress manipulation also increased salivary cortisol, catecholamines as indicated by the presence of alpha-amylase, heart rate, and subjectively reported stress. Stressed subjects reported more false memories than nonstressed control subjects, and these false memories correlated positively with cortisol levels, providing evidence for a relationship between stress and false memory formation. Our results demonstrate that stress, when administered prior to encoding, produces different patterns of long-term remembering for neutral and emotional episodes. These differences likely emerge from differential actions of stress hormones on memory-relevant regions of the brain.
Uguccioni, Ginevra; Pallanca, Olivier; Golmard, Jean-Louis; Leu-Semenescu, Smaranda; Arnulf, Isabelle
In order to evaluate verbal memory consolidation during sleep in subjects experiencing sleepwalking or sleep terror, 19 patients experiencing sleepwalking/sleep terror and 19 controls performed two verbal memory tasks (16-word list from the Free and Cued Selective Reminding Test, and a 220- and 263-word modified story recall test) in the evening, followed by nocturnal video polysomnography (n = 29) and morning recall (night-time consolidation after 14 h, n = 38). The following morning, they were given a daytime learning task using the modified story recall test in reverse order, followed by an evening recall test after 9 h of wakefulness (daytime consolidation, n = 38). The patients experiencing sleepwalking/sleep terror exhibited more frequent awakenings during slow-wave sleep and longer wakefulness after sleep onset than the controls. Despite this reduction in sleep quality among sleepwalking/sleep terror patients, they improved their scores on the verbal tests the morning after sleep compared with the previous evening (+16 ± 33%) equally well as the controls (+2 ± 13%). The performance of both groups worsened during the daytime in the absence of sleep (-16 ± 15% for the sleepwalking/sleep terror group and -14 ± 11% for the control group). There was no significant correlation between the rate of memory consolidation and any of the sleep measures. Seven patients experiencing sleepwalking also sleep-talked during slow-wave sleep, but their sentences were unrelated to the tests or the list of words learned during the evening. In conclusion, the alteration of slow-wave sleep during sleepwalking/sleep terror does not noticeably impact on sleep-related verbal memory consolidation.
Prince, Toni-Moi; Wimmer, Mathieu; Choi, Jennifer; Havekes, Robbert; Aton, Sara; Abel, Ted
Sleep deprivation disrupts hippocampal function and plasticity. In particular, long-term memory consolidation is impaired by sleep deprivation, suggesting that a specific critical period exists following learning during which sleep is necessary. To elucidate the impact of sleep deprivation on long-term memory consolidation and synaptic plasticity, long-term memory was assessed when mice were sleep deprived following training in the hippocampus-dependent object place recognition task. We found that 3h of sleep deprivation significantly impaired memory when deprivation began 1h after training. In contrast, 3 h of deprivation beginning immediately post-training did not impair spatial memory. Furthermore, a 3-h sleep deprivation beginning 1h after training impaired hippocampal long-term potentiation (LTP), whereas sleep deprivation immediately after training did not affect LTP. Together, our findings define a specific 3-h critical period, extending from 1 to 4h after training, during which sleep deprivation impairs hippocampal function.
Prince, Toni-Moi; Wimmer, Mathieu; Choi, Jennifer; Havekes, Robbert; Aton, Sara; Abel, Ted
Sleep deprivation disrupts hippocampal function and plasticity. In particular, long-term memory consolidation is impaired by sleep deprivation, suggesting that a specific critical period exists following learning during which sleep is necessary. To elucidate the impact of sleep deprivation on long-term memory consolidation and synaptic plasticity, long-term memory was assessed when mice were sleep deprived following training in the hippocampus-dependent object place recognition task. We found that 3 hours of sleep deprivation significantly impaired memory when deprivation began 1 hour after training. In contrast, 3 hours of deprivation beginning immediately post-training did not impair spatial memory. Furthermore, a 3-hour sleep deprivation beginning 1 hour after training impaired hippocampal long-term potentiation (LTP), whereas sleep deprivation immediately after training did not affect LTP. Together, our findings define a specific 3-hour critical period, extending from 1 to 4 hours after training, during which sleep deprivation impairs hippocampal function. PMID:24380868
Albouy, Philippe; Mattout, Jeremie; Bouet, Romain; Maby, Emmanuel; Sanchez, Gaetan; Aguera, Pierre-Emmanuel; Daligault, Sebastien; Delpuech, Claude; Bertrand, Olivier; Caclin, Anne; Tillmann, Barbara
Congenital amusia is a lifelong disorder of music perception and production. The present study investigated the cerebral bases of impaired pitch perception and memory in congenital amusia using behavioural measures, magnetoencephalography and voxel-based morphometry. Congenital amusics and matched control subjects performed two melodic tasks (a…
Tompkins, Virginia; Farrar, M. Jeffrey
This study examined the role that mothers' scaffolding plays in the autobiographical memory (AM) and storybook narratives of children with specific language impairment (SLI). Seven 4-5-year-old children and their mothers co-constructed narratives in both contexts. We also compared children's narratives with mothers to their narratives with an…
O'Hearn, Kirsten; Courtney, Susan; Street, Whitney; Landau, Barbara
Williams syndrome (WS) is a neurodevelopmental disorder associated with impaired visuospatial representations subserved by the dorsal stream and relatively strong object recognition abilities subserved by the ventral stream. There is conflicting evidence on whether this uneven pattern in WS extends to working memory (WM). The present studies…
Alzoubi, Karem H; Khabour, Omar F; Tashtoush, Noor H; Al-Azzam, Sayer I; Mhaidat, Nizar M
In this study, we examined the ability of Pentoxifylline (PTX) to prevent sleep deprivation induced memory impairment probably through decreasing oxidative stress. Sleep deprivation was chronically induced 8 h/day for 6 weeks in rats using modified multiple platform model. Concurrently, PTX (100 mg/kg) was administered to animals on daily basis. After 6 weeks of treatment, behavioral studies were conducted to test the spatial learning and memory using the Radial Arm Water Maze. Additionally, the hippocampus was dissected; and levels/activities of antioxidant defense biomarkers glutathione reduced (GSH), glutathione oxidized (GSSG), GSH/GSSG ratio, glutathione peroxidase (GPx), catalase, and superoxide dismutase (SOD), were assessed. The results show that chronic sleep deprivation impaired short- and long-term memories, which was prevented by chronic treatment with PTX. Additionally, PTX normalized sleep deprivation-induced reduction in the hippocampus GSH/GSSG ratio (P < 0.05), and activities of GPx, catalase, and SOD (P < 0.05). In conclusion, chronic sleep deprivation induces memory impairment, and treatment with PTX prevented this impairment probably through normalizing antioxidant mechanisms in the hippocampus.
Oliver, Chris; Holland, Tony; Hall, Scott; Crayton, Lissa
The effect of increasing the number of stimuli to be recalled was investigated to evaluate whether sensitivity for memory impairment was enhanced in adults with Down syndrome when using higher task load. Three levels of load were compared across three groups of adults: those with cognitive deterioration, no cognitive deterioration over age 40, and…
Smalarz, Laura; Wells, Gary L
This research examined whether confirming postidentification feedback following a mistaken identification impairs eyewitness memory for the original culprit. We also examined whether the degree of similarity between a mistakenly identified individual and the actual culprit plays a role in memory impairment. Participant-witnesses (N = 145) made mistaken identifications from a "similar" or a "dissimilar" culprit-absent photo lineup. The similar lineup contained individuals who were similar in appearance to the actual culprit and the dissimilar lineup contained individuals who were dissimilar in appearance to the actual culprit. After their identifications, witnesses were given confirming feedback ("Good job! You identified the suspect.") or no feedback. The experimenter then feigned having accidentally given the witnesses the wrong photo lineup. After telling witnesses to disregard whatever they saw in the first lineup, the experimenter gave witnesses the "correct" (culprit-present) lineup and told the witnesses to do their best to identify the culprit. Identifying a dissimilar individual and receiving confirming feedback after a misidentification had independent impairing effects on memory for the original culprit. Results extend the traditional conceptualization of the postidentification feedback effect by showing that confirming feedback not only distorts witnesses' retrospective self-reports, but it also impairs recognition memory for the culprit.
Archibald, Lisa M. D.; Joanisse, Marc F.; Munson, Benjamin
Purpose: Debate around the underlying cognitive factors leading to poor performance in the repetition of nonwords by children with developmental impairments in language has centered around phonological short-term memory, lexical knowledge, and other factors. This study examines the impact of motor control demands on nonword repetition in groups of…
Martinussen, Rhonda; Hayden, Jill; Hogg-Johnson, Sheilah; Tannock, Rosemary
Objective: To determine the empirical evidence for deficits in working memory (WM) processes in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Method: Exploratory meta-analytic procedures were used to investigate whether children with ADHD exhibit WM impairments. Twenty-six empirical research studies published from…
Lee, Hyeon Yong; Weon, Jin Bae; Jung, Youn Sik; Kim, Nam Young; Kim, Myong Ki; Ma, Choong Je
Aronia melanocarpa (A. melanocarpa) berries are a fruit with a marked antioxidant effect. The objective of this study was to confirm the effect of A. melanocarpa berries extract against scopolamine-induced memory impairment in mice using the Morris water maze and passive avoidance test. Moreover, we determined a possible mechanism of the cognitive-enhancing effect involving AChE activity and BDNF and p-CREB expression in the hippocampus of mice. A. melanocarpa berries extract attenuated the learning and memory impairment induced by scopolamine in the Morris water maze (79.3 ± 0.8 s of 200 mg/kg and 64.4 ± 10.7 s of 400 mg/kg on day 4) and passive avoidance tests (46.0 ± 41.1 s of 200 mg/kg and 25.6 ± 18.7 s of 400 mg/kg). A. melanocarpa berries extract reduced the acetylcholinesterase level in the hippocampus of scopolamine-injected mice and increased BDNF and p-CREB expression in the hippocampus. The major compound, cyanidin-3-O-galactoside, also reversed memory impairment. These results showed that A. melanocarpa berries extract improved memory impairment by inhibiting AChE and increasing BDNF and p-CREB expression, and cyanidin-3-O-galactoside may be responsible for the effect of A. melanocarpa berries extract. PMID:27239211
Vuckovich, Joseph A.; Semel, Mara E.; Baxter, Mark G.
A recent study suggests that lesions to all major areas of the cholinergic basal forebrain in the rat (medial septum, horizontal limb of the diagonal band of Broca, and nucleus basalis magnocellularis) impair a spatial working memory task. However, this experiment used a surgical technique that may have damaged cerebellar Purkinje cells. The…
Lee, Bradley H.; Chan, John Thomas; Hazarika, Obhi; Vutskits, Laszlo; Sall, Jeffrey W.
Background Anesthetic exposure early in life affects neural development and long-term cognitive function, but our understanding of the types of memory that are altered is incomplete. Specific cognitive tests in rodents that isolate different memory processes provide a useful approach for gaining insight into this issue. Methods Postnatal day 7 (P7) rats were exposed to either desflurane or isoflurane at 1 Minimum Alveolar Concentration for 4 h. Acute neuronal death was assessed 12 h later in the thalamus, CA1-3 regions of hippocampus, and dentate gyrus. In separate behavioral experiments, beginning at P48, subjects were evaluated in a series of object recognition tests relying on associative learning, as well as social recognition. Results Exposure to either anesthetic led to a significant increase in neuroapoptosis in each brain region. The extent of neuronal death did not differ between groups. Subjects were unaffected in simple tasks of novel object and object-location recognition. However, anesthetized animals from both groups were impaired in allocentric object-location memory and a more complex task requiring subjects to associate an object with its location and contextual setting. Isoflurane exposure led to additional impairment in object-context association and social memory. Conclusion Isoflurane and desflurane exposure during development result in deficits in tasks relying on associative learning and recognition memory. Isoflurane may potentially cause worse impairment than desflurane. PMID:25165850
Girard, Stéphane D; Jacquet, Marlyse; Baranger, Kévin; Migliorati, Martine; Escoffier, Guy; Bernard, Anne; Khrestchatisky, Michel; Féron, François; Rivera, Santiago; Roman, François S; Marchetti, Evelyne
The 5XFAD mice are an early-onset transgenic model of Alzheimer's disease (AD) in which amyloid plaques are first observed between two and four months of age in the cortical layer five and in the subiculum of the hippocampal formation. Although cognitive alterations have been described in these mice, there are no studies that focused on the onset of hippocampus-dependent memory deficits, which are a hallmark of the prodromal stage of AD. To identify when the first learning and memory impairments appear, 5XFAD mice of two, four, and six months of age were compared with their respective wild-type littermates using the olfactory tubing maze, which is a very sensitive hippocampal-dependent task. Deficits in learning and memory started at four months with a substantial increase at six months of age while no olfactory impairments were observed. The volumetric study using magnetic resonance imaging of the whole brain and specific areas (olfactory bulb, striatum, and hippocampus) did not reveal neuro-anatomical difference. Slight memory deficits appeared at 4 months of age in correlation with an increased astrogliosis and amyloid plaque formation. This early impairment in learning and memory related to the hippocampal dysfunction is particularly suited to assess preclinical therapeutic strategies aiming to delay or suppress the onset of AD.
Li, Wen; Gan, Chen; Lv, Yue; Wang, Shanghu; Cheng, Huaidong
Abstract This study aimed to investigate prospective memory impairment in patients with breast cancer with different expression of hormone receptors, including the estrogen receptor (ER) and the progesterone receptor (PR). A total of 120 patients with breast cancer who underwent chemotherapy following surgery were divided into 2 groups. The A group included 60 patients with ER−/PR− status, and the B group included 60 patients with ER+/PR+ status. After 6 cycles of postoperative adjuvant chemotherapy, all patients were administered neuropsychological and prospective memory tests, such as the Mini-Mental State Examination (MMSE), verbal fluency test (VFT), and digit span test (DST), as well as examination of event-based prospective memory (EBPM) and time-based prospective memory (TBPM). As the neuropsychological background test results showed, there were no significant differences in MMSE, DST, and TBPM scores (∗:P > 0.05) between patients with breast cancer in the ER−/PR− and ER+/PR+ groups, while the VFT and EBPM scores were significantly greater in patients with breast cancer with ER+/PR+ status than in those with ER−/PR− status (∗∗: P < 0.01), indicating that patients with ER−/PR− status have significant impairment in EBPM, although not in TBPM. The results of the present study indicate that different hormone receptor expression in patients with breast cancer may be associated with heterogeneity of chemotherapy-induced prospective memory impairment. PMID:28353608
Hachmann, Wibke M; Bogaerts, Louisa; Szmalec, Arnaud; Woumans, Evy; Duyck, Wouter; Job, Remo
Recent findings suggest that people with dyslexia experience difficulties with the learning of serial order information during the transition from short- to long-term memory (Szmalec et al. Journal of Experimental Psychology: Learning, Memory, & Cognition 37(5): 1270-1279, 2011). At the same time, models of short-term memory increasingly incorporate a distinction of order and item processing (Majerus et al. Cognition 107: 395-419, 2008). The current study is aimed to investigate whether serial order processing deficiencies in dyslexia can be traced back to a selective impairment of short-term memory for serial order and whether this impairment also affects processing beyond the verbal domain. A sample of 26 adults with dyslexia and a group of age and IQ-matched controls participated in a 2 × 2 × 2 experiment in which we assessed short-term recognition performance for order and item information, using both verbal and nonverbal material. Our findings indicate that, irrespective of the type of material, participants with dyslexia recalled the individual items with the same accuracy as the matched control group, whereas the ability to recognize the serial order in which those items were presented appeared to be affected in the dyslexia group. We conclude that dyslexia is characterized by a selective impairment of short-term memory for serial order, but not for item information, and discuss the integration of these findings into current theoretical views on dyslexia and its associated dysfunctions.
Malkova, Ludise; Forcelli, Patrick A; Wellman, Laurie L; Dybdal, David; Dubach, Mark F; Gale, Karen
The perirhinal cortex (PRc) is essential for visual recognition memory, as shown by electrophysiological recordings and lesion studies in a variety of species. However, relatively little is known about the functional contributions of perirhinal subregions. Here we used a systematic mapping approach to identify the critical subregions of PRc through transient, focal blockade of glutamate receptors by intracerebral infusion of kynurenic acid. Nine macaques were tested for visual recognition memory using the delayed nonmatch-to-sample task. We found that inactivation of medial PRc (consisting of Area 35 together with the medial portion of Area 36), but not lateral PRc (the lateral portion of Area 36), resulted in a significant delay-dependent impairment. Significant impairment was observed with 30 and 60 s delays but not with 10 s delays. The magnitude of impairment fell within the range previously reported after PRc lesions. Furthermore, we identified a restricted area located within the most anterior part of medial PRc as critical for this effect. Moreover, we found that focal blockade of either NMDA receptors by the receptor-specific antagonist AP-7 or AMPA receptors by the receptor-specific antagonist NBQX was sufficient to disrupt object recognition memory. The present study expands the knowledge of the role of PRc in recognition memory by identifying a subregion within this area that is critical for this function. Our results also indicate that, like in the rodent, both NMDA and AMPA-mediated transmission contributes to object recognition memory.
Harandi, Shaahin; Golchin, Leila; Ansari, Mehdi; Moradi, Alireza; Shabani, Mohammad; Sheibani, Vahid
Introduction: Alzheimer’s disease (AD) is an age-related neurodegenerative disease, which impairs memory and cognitive function. Walnuts are a dietary source of polyphenols, antioxidants and other compounds with health beneficial effects. These characteristic of walnuts make them perfect candidates for evaluation of their possible effects on neurodegenerative diseases. Therefore the present study was designed to investigate the effects of walnuts consumption (2%, 6% and 9% walnut diets) on memory enhancement and acetylcholinesterase (AChE) activity of brain in scopolamine-induced amnesic rats. Methods: Learning, memory and locomotor activity parameters were evaluated using Morris water maze (MWM), passive avoidance and rotarod tests. Results: Our results showed that consumption of walnuts at doses of 6% and 9% significantly restored the scopolamine-induced memory impairments in the MWM and passive avoidance tests. Moreover, the potential of walnuts to prevent scopolamine neurotoxicity was also reflected by the decreased AChE activity in the whole brain in comparison with the scopolamine group. Discussion: These results suggest that walnuts may be useful against memory impairment and it may exert these anti-amnesic activities via inhibition of AChE activity in the brain. It would be worthwhile to explore the potential of this nut and its active components in the management of the AD. PMID:27307953
Schoofs, Daniela; Preuss, Diana; Wolf, Oliver T
In contrast to the substantial number of studies investigating the effects of stress on declarative memory, effects of stress on working memory have received less attention. We compared working memory (numerical n-back task with single digits) in 40 men exposed either to psychosocial stress (Trier Social Stress Test (TSST)) or a control condition. Task difficulty was varied using two conditions (2-back vs. 3-back). Salivary cortisol (as a marker of hypothalamus-pituitary-adrenal (HPA) activity) and salivary alpha-amylase (sAA as a marker of sympathetic nervous system (SNS) activity) were assessed immediately before and three times after the stress or control condition. As expected stress resulted in an increase in cortisol, sAA, and negative affect. Subjects exposed to stress showed significant working memory impairments in both workload conditions. The analysis of variance indicated a main effect of stress for reaction time as well as accuracy. In addition, for reaction time a stress-block interaction occurred. Follow up tests revealed that only during the first block at each level of difficulty performance was significantly impaired by stress. Thus, the effects of stress became smaller the longer the task was performed. Results provide further evidence for impaired working memory after acute stress and illustrate the time course of this phenomenon.
Ozbaki, Jamile; Goudarzi, Iran; Salmani, Mahmoud Elahdadi; Rashidy-Pour, Ali
Objective(s): Due to the prevalence and pervasiveness of stress in modern life and exposure to both chronic and acute stresses, it is not clear whether prior exposure to chronic stress can influence the impairing effects of acute stress on memory retrieval. This issue was tested in this study. Materials and Methods: Adult male Wistar rats were randomly assigned to the following groups: control, acute, chronic, and chronic + acute stress groups. The rats were trained with six trials per day for 6 consecutive days in the water maze. Following training, the rats were either kept in control conditions or exposed to chronic stress in a restrainer 6 hr/day for 21 days. On day 22, a probe test was done to measure memory retention. Time spent in target and opposite areas, platform location latency, and proximity were used as indices of memory retention. To induce acute stress, 30 min before the probe test, animals received a mild footshock. Results: Stressed animals spent significantly less time in the target quadrant and more time in the opposite quadrant than control animals. Moreover, the stressed animals showed significantly increased platform location latency and proximity as compared with control animals. No significant differences were found in these measures among stress exposure groups. Finally, both chronic and acute stress significantly increased corticosterone levels. Conclusion: Our results indicate that both chronic and acute stress impair memory retrieval similarly. Additionally, the impairing effects of chronic stress on memory retrieval were not influenced by acute stress. PMID:27635201
WANG, HUIMIN; WANG, HUILING; CHENG, HUIXIN; CHE, ZHENYONG
Alzheimer's disease (AD) is one of the most prevalent neurodegenerative disorder. It is characterized by the formation of amyloid plaques and neurofibrillary tangles in the brain, the degeneration of cholinergic neurons and neuronal cell death. The present study aimed to investigate the effect of luteolin, a flavonoid compound, on memory impairment in a streptozotocin (STZ)-induced Alzheimer's rat model. Morris water maze and probe tests were performed to examine the effect of luteolin treatment on cognition and memory. The effect of luteolin on CA1 pyramidal layer thickness was also examined. The results demonstrated that luteolin significantly ameliorated the spatial learning and memory impairment induced by STZ treatment. STZ significantly reduced the thickness of CA1 pyramidal layer and treatment of luteolin completely abolished the inhibitory effect of STZ. Our results suggest that luteolin has a potentially protective effect on learning defects and hippocampal structures in AD. PMID:27035793
Turk, David J; Brady-van den Bos, Mirjam; Collard, Philip; Gillespie-Smith, Karri; Conway, Martin A; Cunningham, Sheila J
Information that is relevant to oneself tends to be remembered more than information that relates to other people, but the role of attention in eliciting this "self-reference effect" is unclear. In the present study, we assessed the importance of attention in self-referential encoding using an ownership paradigm, which required participants to encode items under conditions of imagined ownership by themselves or by another person. Previous work has established that this paradigm elicits a robust self-reference effect, with more "self-owned" items being remembered than "other-owned" items. Access to attentional resources was manipulated using divided-attention tasks at encoding. A significant self-reference effect emerged under full-attention conditions and was related to an increase in episodic recollection for self-owned items, but dividing attention eliminated this memory advantage. These findings are discussed in relation to the nature of self-referential cognition and the importance of attentional resources at encoding in the manifestation of the self-reference effect in memory.
Pearce, R. A.; Duscher, P.; Van Dyke, K.; Lee, M.; Andrei, A. C.; Perouansky, M.
Background Anaesthetics suppress the formation of lasting memories at concentrations that do not suppress perception, but it is unclear which elements of the complex cascade leading from a conscious experience to a lasting memory trace are disrupted. Experiments in conscious humans suggest that subhypnotic concentrations of anaesthetics impair consolidation or maintenance rather than acquisition of a representation (long-term more than short-term memory). We sought to test whether these agents similarly impair learning in rats. Methods We used operant conditioning in rats to examine the effect of isoflurane on acquisition compared with long-term (24 h) memory of non-aversive olfactory memories using two different odour discrimination tasks. Rats learned the ‘valences’ of odour pairs presented either separately (task A) or simultaneously (task B), under control conditions and under isoflurane inhalation. In a separate set of experiments, we tested the ability of the animals to recall a learning set that had been acquired 24 h previously. Results Under 0.4% isoflurane inhalation, the average number of trials required to reach criterion performance (18 correct responses in 20 successive trials) increased from 21.9 to 43.5 (P<0.05) and 24.2 to 54.4 (P<0.05) for tasks A and B, respectively. Under 0.3% isoflurane inhalation, only task B was impaired (from 24.2 to 31.5 trials, P<0.05). Recall at 24 h was dose-dependently impaired or prevented by isoflurane for both tasks. Conclusions Isoflurane interfered with long-term memory of odour valence without preventing its acquisition. This paradigm may serve as a non-aversive animal model of conscious amnesia. PMID:22258200
Yang, Shengchang; Wen, Di; Dong, Mei; Li, Dong; Sun, Donglei; Ma, Chunling; Cong, Bin
Acute and chronic exposure to opiate drugs impaired various types of memory processes. To date, there is no preventive treatment for opiate-induced memory impairment and the related mechanism is still unclear. CCK-8 is the most potent endogenous anti-opioid peptide and has been shown to exert memory-enhancing effect, but the effect of CCK-8 on morphine-induced memory impairment has not been reported. By using Morris water maze, we found that escape latency to the hidden platform in navigation test was not influenced, but performance in the probe test was seriously poor in morphine dependency mice. Amnesia induced by chronic morphine treatment was significantly alleviated by pre-treatment with CCK-8 (0.01, 0.1 and 1 μg, i.c.v.), and CCK-8 (0.1 and 1 μg, i.c.v.) treatment alone could improve performance in either navigation or probe test. Furthermore, Golgi-Cox staining analysis revealed that pre-treatment with CCK-8 (1 μg, i.c.v.) reversed spine density decreased in CA1 region of hippocampus in morphine dependency mice, and CCK-8 (1 μg, i.c.v.) alone obviously increased spine density in CA1. Our findings conclude spine density change in CA1 region of hippocampus may be the structural plasticity mechanism which is responsible for enhancing effect of CCK-8 on spatial reference memory. Therefore, CCK-8 could effectively improve memory impairment in morphine dependency mice.
Gale, Shawn D; Baxter, Leslie; Thompson, Juliann
Previously we demonstrated sex differences in episodic memory in healthy elderly and suggested that normative data be separated by sex. The present study extended the exploration of sex differences on memory measures into two clinical populations, mild cognitive impairment (MCI) and Alzheimer's disease (AD). Seventy-six subjects with MCI and 101 subjects with AD diagnosed by a multidisciplinary team were included. These two groups were also compared to a group of 177 healthy elderly control participants. Sex differences on the Rey Auditory Verbal Learning Test (RAVLT; total and delayed recall) raw scores and Brief Visuospatial Memory Test-Revised (BVMT-R) were demonstrated within the healthy but not the MCI or AD groups. Calculating z scores by sex for both dementing groups based on the healthy controls suggested a larger performance gap between healthy and dementing women than between healthy and dementing men. MCI females were on average 0.48 standard deviations lower for total verbal learning compared to healthy female controls than were MCI males when compared to healthy male controls. For verbal delayed recall the gap was even larger (SD = 1.09). Similarly, on the BVMT-R, a measure of visual memory, the difference was 0.60 standard deviations for total visual learning and 0.99 standard deviations for delayed recall. This same sex difference, with females showing greater impairment compared to the controls group than did the males, was also present within the AD group. The greater memory impairment in dementing females rather than males when compared to sex-matched healthy controls was unlikely to be due to more severe illness since females performed equivalently to males on the Clinical Dementia Rating Scale, Mini-Mental Status Examination, and Dementia Rating Scale, and were also similar for age, education, and apolipoprotein status. The present study suggested relatively greater memory impairment in females with MCI or AD than in controls.
Cooper, Janine M.; Gadian, David G.; Jentschke, Sebastian; Goldman, Allan; Munoz, Monica; Pitts, Georgia; Banks, Tina; Chong, W. Kling; Hoskote, Aparna; Deanfield, John; Baldeweg, Torsten; de Haan, Michelle; Mishkin, Mortimer; Vargha-Khadem, Faraneh
Neonates treated for acute respiratory failure experience episodes of hypoxia. The hippocampus, a structure essential for memory, is particularly vulnerable to such insults. Hence, some neonates undergoing treatment for acute respiratory failure might sustain bilateral hippocampal pathology early in life and memory problems later in childhood. We investigated this possibility in a cohort of 40 children who had been treated neonatally for acute respiratory failure but were free of overt neurological impairment. The cohort had mean hippocampal volumes (HVs) significantly below normal control values, memory scores significantly below the standard population means, and memory quotients significantly below those predicted by their full scale IQs. Brain white matter volume also fell below the volume of the controls, but brain gray matter volumes and scores on nonmnemonic neuropsychological tests were within the normal range. Stepwise linear regression models revealed that the cohort's HVs were predictive of degree of memory impairment, and gestational age at treatment was predictive of HVs: the younger the age, the greater the atrophy. We conclude that many neonates treated for acute respiratory failure sustain significant hippocampal atrophy as a result of the associated hypoxia and, consequently, show deficient memory later in life. PMID:24343890
Cooper, Janine M; Gadian, David G; Jentschke, Sebastian; Goldman, Allan; Munoz, Monica; Pitts, Georgia; Banks, Tina; Chong, W Kling; Hoskote, Aparna; Deanfield, John; Baldeweg, Torsten; de Haan, Michelle; Mishkin, Mortimer; Vargha-Khadem, Faraneh
Neonates treated for acute respiratory failure experience episodes of hypoxia. The hippocampus, a structure essential for memory, is particularly vulnerable to such insults. Hence, some neonates undergoing treatment for acute respiratory failure might sustain bilateral hippocampal pathology early in life and memory problems later in childhood. We investigated this possibility in a cohort of 40 children who had been treated neonatally for acute respiratory failure but were free of overt neurological impairment. The cohort had mean hippocampal volumes (HVs) significantly below normal control values, memory scores significantly below the standard population means, and memory quotients significantly below those predicted by their full scale IQs. Brain white matter volume also fell below the volume of the controls, but brain gray matter volumes and scores on nonmnemonic neuropsychological tests were within the normal range. Stepwise linear regression models revealed that the cohort's HVs were predictive of degree of memory impairment, and gestational age at treatment was predictive of HVs: the younger the age, the greater the atrophy. We conclude that many neonates treated for acute respiratory failure sustain significant hippocampal atrophy as a result of the associated hypoxia and, consequently, show deficient memory later in life.
Peng, Sheng; Zhang, Yan; Wang, Hua; Ren, Bingxu; Zhang, Jiannan
The aim of this study is to investigate whether ketamine, a noncompetitive N-methyl-D: -aspartate receptor (NMDAR) antagonist, had an influence on learning and memory in developing mice. Fifty Kunming mice aged 21 days were randomly divided into 5 subgroups (n = 10 for each) to receive intraperitoneal injection of equal volume of saline (S group) or ketamine (25, 50 or 100 mg/kg of body weight/day) for 7 consecutive days, or to be left untreated (C group). A step-down passive avoidance test was performed to evaluate learning and memory in these mice on days 8 and 9. Additionally, the expression of brain-derived neurotrophic factor (BDNF) in the hippocampus was determined. Rats receiving saline or sub-anesthetic dose of ketamine (25 mg/kg) showed significantly decreased abilities of learning and memory and reduced expression of BDNF, compared to the normal controls (P < 0.05). In contrast, comparable abilities of learning and memory and expression of BDNF were found for anesthetic doses of ketamine (50 or 100 mg/kg)-treated rats and controls (P > 0.05). Repetitive mechanical stress impairs learning and memory performance in developing mice, which may be associated with decreased BDNF expression. The stress-induced learning and memory impairment can be prevented by anesthetic doses of ketamine.
Jakobson, L S; Pearson, P M; Robertson, B
Cases of hue-selective dyschomatopsias, together with the results of recent optical imaging studies [Xiao, Y., Casti, A. R. R., Xiao, J., & Kaplan, E. (2006). A spatially organized representation of colour in macaque primary visual cortex. Perception, 35, ECVP Abstract Supplement; Xiao, Y., Wang, Y., & Felleman, D. J. (2003). A spatially organized representation of colour in macaque cortical area V2. Nature, 421, 535-539], have provided support for the idea that different colours are processed in spatially distinct regions of extrastriate cortex. In the present report, we provide evidence suggesting that a similar, but distinct, map may exist for representations of colour in memory. This evidence comes from observations of a young woman (QP) who demonstrates an isolated deficit in colour memory secondary to a concussive episode. Despite having normal colour perception and colour naming skills, and above-average memory skills in other domains, QP's ability to recall visually encoded colour information over short retention intervals is dramatically impaired. Her long-term memory for colour and her colour imagery skills are also abnormal. Surprisingly, however, these impairments are not seen with all hues; specifically, her ability to remember or imagine blue shades is spared. This interesting case contributes to the literature suggesting that colour perception, naming, and memory can be clinically dissociated, and provides insights into the organization of colour information in memory.
Mesripour, Azadeh; Rafieian-Kopaei, Mahmoud; Bahrami, Bahareh
Since Anethum graveolens (Dill) has phytoestrogenic compounds and it is proven that estrogens exert beneficial effects on cognition; the aim of this study was to understand if this plant can improve memory performance. Male Balb/c mice weighing 25-30 g were used in this study and memory was assessed by the novel object recognition task. In this method, the difference in the exploration time between a familiar object and a novel object is taken as an index of memory performance (recognition index, RI). Scopolamine significantly reduced memory index (RI = -15.5% ± 3.0). Dill essence (100 mg/kg, ip) prevented the harmful effects of scopolamine on memory (RI = 40% ± 5.5), thus RI did not differ with control animals (RI = 50% ± 5.8). In addition, 17-β estradiol also prevented memory impairment in animals (0.2 mg/kg, ip; RI = 35.8% ± 6.5). Nevertheless, the beneficial effects of dill essence were antagonized by prior injection of tamoxifen (1 mg/kg, ip; RI = -30% ± 7.8). Although phytoesrogens are not steroids, the beneficial effect of dill on memory, at least in part, may have been achieved by estrogenic receptors present in the brain. Thus dill essence could be promising in improving memory and cognition, mainly in postmenopausal women.
Mesripour, Azadeh; Rafieian-Kopaei, Mahmoud; Bahrami, Bahareh
Since Anethum graveolens (Dill) has phytoestrogenic compounds and it is proven that estrogens exert beneficial effects on cognition; the aim of this study was to understand if this plant can improve memory performance. Male Balb/c mice weighing 25-30 g were used in this study and memory was assessed by the novel object recognition task. In this method, the difference in the exploration time between a familiar object and a novel object is taken as an index of memory performance (recognition index, RI). Scopolamine significantly reduced memory index (RI = -15.5% ± 3.0). Dill essence (100 mg/kg, ip) prevented the harmful effects of scopolamine on memory (RI = 40% ± 5.5), thus RI did not differ with control animals (RI = 50% ± 5.8). In addition, 17-β estradiol also prevented memory impairment in animals (0.2 mg/kg, ip; RI = 35.8% ± 6.5). Nevertheless, the beneficial effects of dill essence were antagonized by prior injection of tamoxifen (1 mg/kg, ip; RI = -30% ± 7.8). Although phytoesrogens are not steroids, the beneficial effect of dill on memory, at least in part, may have been achieved by estrogenic receptors present in the brain. Thus dill essence could be promising in improving memory and cognition, mainly in postmenopausal women. PMID:27168754
KHALIL, Amr Farid; IWASAKI, Masaki; NISHIO, Yoshiyuki; JIN, Kazutaka; NAKASATO, Nobukazu; TOMINAGA, Teiji
Post-operative memory changes after temporal lobe surgery have been established mainly by group analysis of cognitive outcome. This study investigated individual patient-based memory outcome in surgically-treated patients with mesial temporal lobe epilepsy (TLE). This study included 84 consecutive patients with intractable TLE caused by unilateral hippocampal sclerosis (HS) who underwent epilepsy surgery (47 females, 41 left [Lt] TLE). Memory functions were evaluated with the Wechsler Memory Scale-Revised before and at 1 year after surgery. Pre-operative memory function was classified into three patterns: verbal dominant memory impairment (Verb-D), visual dominant impairment (Vis-D), and no material-specific impairment. Post-operative changes in verbal and visual memory indices were classified into meaningful improvement, worsening, or no significant changes. Pre-operative patterns and post-operative changes in verbal and visual memory function were compared between the Lt and right (Rt) TLE groups. Pre-operatively, Verb-D was the most common type of impairment in both the Lt and Rt TLE groups (65.9 and 48.8%), and verbal memory indices were lower than visual memory indices, especially in the Lt compared with Rt TLE group. Vis-D was observed only in 11.6% of Rt and 7.3% of Lt TLE patients. Post-operatively, meaningful improvement of memory indices was observed in 23.3–36.6% of the patients, and the memory improvement was equivalent between Lt and Rt TLE groups and between verbal and visual materials. In conclusion, Verb-D is most commonly observed in patients with both the Lt and Rt TLE associated with HS. Hippocampectomy can improve memory indices in such patients regardless of the side of surgery and the function impaired. PMID:27250575
Fortunato-Tavares, Talita; Andrade, Claudia R F; Befi-Lopes, Debora; Limongi, Suelly O; Fernandes, Fernanda D M; Schwartz, Richard G
This study examined syntactic assignment for predicates and reflexives as well as working memory effects in the sentence comprehension of children with Specific Language Impairment (SLI), Down syndrome (DS), high functioning Autism (HFA) and Typical Language Development (TLD). Fifty-seven children (35 boys and 22 girls) performed a computerised picture-selection sentence comprehension task. Predicate attachment and reflexive antecedent assignment (with working memory manipulations) were investigated. The results showed that SLI, HFA and DS children exhibited poorer overall performance than TLD children. Children with SLI exhibited similar performance to the DS and HFA children only when working memory demands were higher. We conclude that children with SLI, HFA and DS differ from children with TLD in their comprehension of predicate and reflexive structures where the knowledge of syntactic assignment is required. Working memory manipulation had different effects on syntactic comprehension depending on language disorder. Intelligence was not an explanatory factor for the differences observed in performance.
Wise, Laura E; Thorpe, Andrew J; Lichtman, Aron H
It is firmly established that the hippocampus, a brain region implicated in spatial learning, episodic memory, and consolidation, contains a high concentration of CB(1) receptors. Moreover, systemic and intrahippocampal administration of cannabinoid agonists have been shown to impair hippocampal-dependent memory tasks. However, the degree to which CB(1) receptors in the hippocampus play a specific functional role in the memory disruptive effects of marijuana or its primary psychoactive constituent Delta(9)-tetrahydrocannabinol (Delta(9)-THC) is unknown. This study was designed to determine whether hippocampal CB(1) receptors play a functional role in the memory disruptive effects of systemically administered cannabinoids, using the radial arm maze, a well characterized rodent model of working memory. Male Sprague-Dawley rats were implanted with bilateral cannulae aimed at the CA1 region of the dorsal hippocampus. The CB(1) receptor antagonist, rimonabant, was delivered into the hippocampus before to a systemic injection of either Delta(9)-THC or the potent cannabinoid analog, CP-55,940. Strikingly, intrahippocampal administration of rimonabant completely attenuated the memory disruptive effects of both cannabinoids in the radial arm maze task, but did not affect other pharmacological properties of cannabinoids, as assessed in the tetrad assay (that is, hypomotility, analgesia, catalepsy, and hypothermia). Infusions of rimonabant just dorsal or ventral to the hippocampus did not prevent Delta(9)-THC-induced memory impairment, indicating that its effects on mnemonic function were regionally selective. These findings provide compelling evidence in support of the view that hippocampal CB(1) receptors play a necessary role in the memory disruptive effects of marijuana.
Nephew, Benjamin C.; Bridges, Robert S.
Primiparous female rats rapidly respond to foster pups following an extended separation from pups after an initial maternal experience. This consolidation of maternal behavior has been referred to as maternal memory. The neurochemical regulation of maternal memory is not clearly understood. One neuropeptide that may mediate maternal memory is arginine vasopressin (AVP), a neuropeptide which is modulated around the time of parturition and has an established role in learning and memory processes. Thus, the present studies examine the possible involvement of AVP in the establishment of maternal memory in female rats. Pregnant rats were implanted with chronic cannulae connected to subcutaneous osmotic minipumps filled with a V1a receptor antagonist [d(CH2)5Tyr(Me)AVP, 0.1–12.5 ng/hr] or saline vehicle which were chronically infused either into the lateral ventricles or bilaterally into the medial amygdala beginning on day 18 of gestation. Both the osmotic pumps and the newborn pups were removed 24 hours following parturition. The effects of the V1a antagonist treatments on social recognition and maternal behavior were measured following parturition and maternal memory was assessed following a ten day separation from pups. Whereas none of the AVP treatments affected the initial establishment of maternal behavior postpartum, maternal memory was impaired in rats infused into the amygdala with the AVP antagonist (1.25 and 12.5 ng/hr). Social recognition was not impaired by intracerebroventricular infusion of either the 0.1 or 1.0 ng/hr dose of the V1a antagonist. The present results suggest a role for medial amygdaloid V1a receptors in the establishment of maternal memory. PMID:18620713
Darwish, Deya S.; Wang, Desheng; Konat, Gregory W.; Schreurs, Bernard G.
Cholesterol and sulfatides play many important roles in learning and memory. To date, our observations about the effects of cholesterol on learning have been assessed during response acquisition i.e., the learning of a new memory. Here we report for the first time on the effect of a cholesterol diet on a previously formed memory. Rabbits were given trace conditioning of the nictitating membrane response for ten days, then fed a 2% cholesterol diet for eight weeks, and then assessed for memory recall of the initially learned task. We show that dietary cholesterol had an adverse effect on memory recall. Second, we investigated whether dietary cholesterol caused an increase in brain cholesterol and sulfatide levels in four major brain structures (hippocampus, frontal lobe, brainstem, and cerebellum) using a technique for analyzing myelin and myelin-free fractions separately. Although our data confirm previous findings that dietary cholesterol does not directly affect cholesterol and establish that it does not affect sulfatide levels in the brain, these levels did increase rather significantly in the hippocampus and frontal lobe as a function of learning and memory. PMID:20141286
Das, Sandhitsu R; Mancuso, Lauren; Olson, Ingrid R; Arnold, Steven E; Wolk, David A
Short-term memory (STM) has generally been thought to be independent of the medial temporal lobe (MTL) in contrast to long-term memory (LTM). Prodromal Alzheimer's disease (AD) is a condition in which the MTL is a major early focus of pathology and LTM is thought disproportionately affected relative to STM. However, recent studies have suggested a role for the MTL in STM, particularly hippocampus, when binding of different elements is required. Other work has suggested involvement of extrahippocampal MTL structures, particularly in STM tasks that involve item-level memory. We examined STM for individual objects, locations, and object-location conjunctions in amnestic mild cognitive impairment (MCI), often associated with prodromal AD. Relative to age-matched, cognitively normal controls, MCI patients not only displayed impairment on object-location conjunctions but were similarly impaired for non-bound objects and locations. Moreover, across all participants, these conditions displayed dissociable correlations of cortical thinning along the long axis of the MTL and associated cortical nodes of anterior and posterior MTL networks. These findings support the role of the MTL in visual STM tasks and the division of labor of MTL in support of different types of memory representations, overlapping with findings in LTM.
Abareshi, Azam; Anaeigoudari, Akbar; Norouzi, Fatemeh; Shafei, Mohammad Naser; Khazaei, Majid
Introduction. Renin-angiotensin system has a role in inflammation and also is involved in many brain functions such as learning, memory, and emotion. Neuroimmune factors have been proposed as the contributors to the pathogenesis of memory impairments. In the present study, the effect of captopril on spatial memory and synaptic plasticity impairments induced by lipopolysaccharide (LPS) was investigated. Methods. The rats were divided and treated into control (saline), LPS (1 mg/kg), LPS-captopril (LPS-Capto; 50 mg/kg captopril before LPS), and captopril groups (50 mg/kg) before saline. Morris water maze was done. Long-term potentiation (LTP) from CA1 area of hippocampus was assessed by 100 Hz stimulation in the ipsilateral Schaffer collateral pathway. Results. In the LPS group, the spent time and traveled path to reach the platform were longer than those in the control, while, in the LPS-Capto group, they were shorter than those in the LPS group. Moreover, the slope and amplitude of field excitatory postsynaptic potential (fEPSP) decreased in the LPS group, as compared to the control group, whereas, in the LPS-Capto group, they increased compared to the LPS group. Conclusion. The results of the present study showed that captopril improved the LPS-induced memory and LTP impairments induced by LPS in rats. Further investigations are required in order to better understand the exact responsible mechanism(s). PMID:27830176
Zhao, Shan-shan; Yang, Wei-na; Jin, Hui; Ma, Kai-ge; Feng, Gai-feng
Puerarin (PUE), an isoflavone purified from the root of Pueraria lobata (Chinese herb), has been reported to attenuate learning and memory impairments in the transgenic mouse model of Alzheimer's disease (AD). In the present study, we tested PUE in a sporadic AD (SAD) mouse model which was induced by the intracerebroventricular injection of streptozotocin (STZ). The mice were administrated PUE (25, 50, or 100mg/kg/d) for 28 days. Learning and memory abilities were assessed by the Morris water maze test. After behavioral test, the biochemical parameters of oxidative stress (glutathione peroxidase (GSH-Px), superoxide dismutases (SOD), and malondialdehyde (MDA)) were measured in the cerebral cortex and hippocampus. The SAD mice exhibited significantly decreased learning and memory ability, while PUE attenuated these impairments. The activities of GSH-Px and SOD were decreased while MDA was increased in the SAD animals. After PUE treatment, the activities of GSH-Px and SOD were elevated, and the level of MDA was decreased. The middle dose PUE was more effective than others. These results indicate that PUE attenuates learning and memory impairments and inhibits oxidative stress in STZ-induced SAD mice. PUE may be a promising therapeutic agent for SAD.
Fá, M; Puzzo, D; Piacentini, R; Staniszewski, A; Zhang, H; Baltrons, M A; Li Puma, D D; Chatterjee, I; Li, J; Saeed, F; Berman, H L; Ripoli, C; Gulisano, W; Gonzalez, J; Tian, H; Costa, J A; Lopez, P; Davidowitz, E; Yu, W H; Haroutunian, V; Brown, L M; Palmeri, A; Sigurdsson, E M; Duff, K E; Teich, A F; Honig, L S; Sierks, M; Moe, J G; D'Adamio, L; Grassi, C; Kanaan, N M; Fraser, P E; Arancio, O
Non-fibrillar soluble oligomeric forms of amyloid-β peptide (oAβ) and tau proteins are likely to play a major role in Alzheimer's disease (AD). The prevailing hypothesis on the disease etiopathogenesis is that oAβ initiates tau pathology that slowly spreads throughout the medial temporal cortex and neocortices independently of Aβ, eventually leading to memory loss. Here we show that a brief exposure to extracellular recombinant human tau oligomers (oTau), but not monomers, produces an impairment of long-term potentiation (LTP) and memory, independent of the presence of high oAβ levels. The impairment is immediate as it raises as soon as 20 min after exposure to the oligomers. These effects are reproduced either by oTau extracted from AD human specimens, or naturally produced in mice overexpressing human tau. Finally, we found that oTau could also act in combination with oAβ to produce these effects, as sub-toxic doses of the two peptides combined lead to LTP and memory impairment. These findings provide a novel view of the effects of tau and Aβ on memory loss, offering new therapeutic opportunities in the therapy of AD and other neurodegenerative diseases associated with Aβ and tau pathology.
Tuzcu, Mehmet; Baydas, Giyasettin
Previous studies indicate that diabetes mellitus might be accompanied by a certain erosion of brain function such as cognitive impairment. The aim of this study was to examine and compare the effects of melatonin and vitamin E on cognitive functions in diabetic rats. Diabetes was induced in male albino rats via intraperitoneal streptozotocin injection. Learning and memory behaviors were investigated using a spatial version of the Morris water maze test. The levels of lipid peroxidation and glutathione were detected in hippocampus and frontal cortex. The diabetic rats developed significant impairment in learning and memory behaviors as indicated by the deficits in water maze tests as compared to control rats. Furthermore, lipid peroxidation levels increased and glutathione concentration decreased in diabetic rats. Treatment with melatonin and vitamin E significantly ameliorated learning and memory performance. Furthermore, both antioxidants reversed lipid peroxidation and glutathione levels toward their control values. These results suggest that oxidative stress may contribute to learning and memory deficits in diabetes and further suggest that antioxidant melatonin and vitamin E can improve cognitive impairment in streptozotocin-induced diabetes.
Kitanaka, Junichi; Kitanaka, Nobue; Hall, F Scott; Fujii, Mei; Goto, Akiko; Kanda, Yusuke; Koizumi, Akira; Kuroiwa, Hirotoshi; Mibayashi, Satoko; Muranishi, Yumi; Otaki, Soichiro; Sumikawa, Minako; Tanaka, Koh-ichi; Nishiyama, Nobuyoshi; Uhl, George R; Takemura, Motohiko
In the present study, the effects of morphine were examined on tests of spatial memory, object exploration, locomotion, and anxiety in male ICR mice. Administration of morphine (15 or 30 mg/kg, intraperitoneally (i.p.)) induced a significant decrease in Y-maze alternations compared to saline vehicle-treated mice. The reduced Y-maze alternations induced by morphine were completely blocked by naloxone (15 mg/kg) or β-funaltrexamine (5 mg/kg) but not by norbinaltorphimine (5 mg/kg) or naltrindole (5 mg/kg), suggesting that the morphine-induced spatial memory impairment was mediated predominantly by μ-opioid receptors (MOPs). Significant spatial memory retrieval impairments were observed in the Morris water maze (MWM) in mice treated with morphine (15 mg/kg) or scopolamine (1 mg/kg), but not with naloxone or morphine plus naloxone. Reduced exploratory time was observed in mice after administration of morphine (15 mg/kg), in a novel-object exploration test, without any changes in locomotor activity. No anxiolytic-like behavior was observed in morphine-treated mice in the elevated plus maze. A significant reduction in buried marbles was observed in morphine-treated mice measured in the marble-burying test, which was blocked by naloxone. These observations suggest that morphine induces impairments in spatial short-term memory and retrieval, and reduces exploratory behavior, but that these effects are not because of overall changes in locomotion or anxiety. PMID:25987850
Funayama, Michitaka; Nakagawa, Yoshitaka; Sunagawa, Kosaku
Although it has been proposed that visuospatial working memory may be impaired in Bálint syndrome patients, neither a systematic study concerning this proposal nor a comparison with patients having right-parietal damage has been made. Visuospatial working memory was assessed for six Bálint syndrome patients and members of two control groups-one composed of individuals with right-parietal damage (n = 15) and a second of age- and gender-matched healthy individuals (n = 26). We placed special emphasis on patients with a mild form of Bálint syndrome who can judge positional relationships between two objects. First, the participants were subjected to delayed visuospatial matching tasks. Next, their visuospatial-temporal integration abilities were assessed using a shape-from-moving-dots task. Visuospatial working memory was impaired for Bálint syndrome patients compared with controls according to the results of the tests. The differences between the Bálint syndrome and control subjects remained when only data for patients with the mild form of Bálint syndrome were included. We conclude that visuospatial working memory may be severely impaired in Bálint syndrome patients and, therefore, might influence their inability to properly execute movements and behaviours associated with daily living.
Zhang, Kun; Li, Yu-jiao; Feng, Dan; Zhang, Peng; Wang, Ya-tao; Li, Xiang; Liu, Shui-bing; Wu, Yu-mei; Zhao, Ming-gao
Sleep disorder is becoming a widespread problem in current society, and is associated with impaired cognition and emotional disorders. Progranulin (PGRN), also known as granulin epithelin precursor, promotes neurite outgrowth and cell survival, and is encoded by the GRN gene. It is a tumor necrosis factor α receptor (TNFR) ligand which is implicated in many central nervous system diseases. However, the role PGRN in sleep disorder remains unclear. In the present study, we found that sleep deprivation (S-DEP) impaired the memory and produced thigmotaxis/anxiety-like behaviors in mice. S-DEP increased the levels of TNFα but decreased PGRN levels in the hippocampus. The intracerebroventricular (ICV) injection of PGRN or intraperitoneal injection of TNFα synthesis blocker thalidomide (25 mg/kg), prevented the memory impairment and anxiety behaviors induced by S-DEP. PGRN treatment also restored dendritic spine density in the hippocampus CA1 region and neurogenesis in hippocampus dentate gyrus (DG). These results indicate that an imbalance between TNFα and PGRN contributes to memory impairment and thigmotaxis/anxiety caused by sleep deprivation. PMID:28300056
Tian, Dan; Tian, Miao; Ma, Zhiming; Zhang, Leilei; Cui, Yunfeng; Li, Jinlong
Postoperative cognitive impairment is especially common in older patients following major surgery. Although exposure to sevoflurane is known to cause memory deficits, few studies have examined the putative approaches to reduce such impairments. This study tested the hypotheses that sevoflurane exposure can decrease NR2B subunit-containing NMDA receptor activity in hippocampus of aged mice, and voluntary exercise may counteract the declining hippocampal functions. We found that long exposure (3 h/day for 3 days), but not short exposure (1 h/day for 3 days), to 3 % sevoflurane produced a long-lasting spatial memory deficits up to 3 weeks in aged mice, and such an effect was not due to the neuronal loss in the hippocampus, but was correlated with a long-term decrease in Fyn kinase expression and NR2B subunit phosphorylation in the hippocampus. Furthermore, voluntary exercise rescued sevoflurane-induced spatial memory deficits in aged mice and restored Fyn kinase expression and NR2B subunit phosphorylation in the hippocampus to a level comparable to control animals. Generally, our results suggested that Fyn-mediated NR2B subunit phosphorylation may play a critical role in sevoflurane-induced impairment in cognitive functions in aged animals, and voluntary exercise might be an important non-pharmacological approach to treatment of inhaled anesthetics-induced postoperative cognitive impairment in clinical settings.
Zhang, Kun; Li, Yu-Jiao; Feng, Dan; Zhang, Peng; Wang, Ya-Tao; Li, Xiang; Liu, Shui-Bing; Wu, Yu-Mei; Zhao, Ming-Gao
Sleep disorder is becoming a widespread problem in current society, and is associated with impaired cognition and emotional disorders. Progranulin (PGRN), also known as granulin epithelin precursor, promotes neurite outgrowth and cell survival, and is encoded by the GRN gene. It is a tumor necrosis factor α receptor (TNFR) ligand which is implicated in many central nervous system diseases. However, the role PGRN in sleep disorder remains unclear. In the present study, we found that sleep deprivation (S-DEP) impaired the memory and produced thigmotaxis/anxiety-like behaviors in mice. S-DEP increased the levels of TNFα but decreased PGRN levels in the hippocampus. The intracerebroventricular (ICV) injection of PGRN or intraperitoneal injection of TNFα synthesis blocker thalidomide (25 mg/kg), prevented the memory impairment and anxiety behaviors induced by S-DEP. PGRN treatment also restored dendritic spine density in the hippocampus CA1 region and neurogenesis in hippocampus dentate gyrus (DG). These results indicate that an imbalance between TNFα and PGRN contributes to memory impairment and thigmotaxis/anxiety caused by sleep deprivation.
Balaban, Pavel M.; Vinarskaya, Alia Kh.; Zuzina, Alena B.; Ierusalimsky, Victor N.; Malyshev, Aleksey Yu.
We analyzed changes in the activity of individually identifiable neurons involved in the networks underlying feeding and withdrawal behaviors in snails before, during, and after aversive learning in vitro. Responses to food in the “reinforcing” serotonergic neurons involved in withdrawal changed significantly after training, implying that these serotonergic cells participate in the reactivation of memory and are involved in the reconsolidation process. In behavioral experiments it was shown that impairment of the functioning of the serotonergic system with the selective neurotoxin 5,7-DiHT did not change the memory, when tested once, but resulted in a complete extinction of the contextual memory after repeated reactivation of memory. Conversely, the cued memory to a specific type of food was significantly reduced but still present. Thus, we conclude that it is only for the context memory, that participation of the “reinforcing” serotonergic neurons in memory retrieval may be the gate condition for the choice between extinction/reconsolidation. PMID:27841309
Christensen, Bruce K; Patrick, Regan E; Stuss, Donald T; Gillingham, Susan; Zipursky, Robert B
Schizophrenia (SCZ)-related verbal memory impairment is hypothesized to be mediated, in part, by frontal lobe (FTL) dysfunction. However, little research has contrasted the performance of SCZ patients with that of patients exhibiting circumscribed frontal lesions. The current study compared verbal episodic memory in patients with SCZ and focal FTL lesions (left frontal, LF; right frontal, RF; and bi-frontal, BF) on a four-trial list learning task consisting of three lists of varying semantic organizational structure. Each dependent variable was examined at two levels: scores collapsed across all four trials and learning scores (i.e., trial 4-trial 1). Performance deficits were observed in each patient group across most dependent measures at both levels. Regarding patient group differences, SCZ patients outperformed LF/BF patients (i.e., either learning scores or scores collapsed across trial) on free recall, primacy, primary memory, secondary memory, and subjective organization, whereas they only outperformed RF patients on the semantically blocked list on recency and primary memory. Collectively, these results indicate that the pattern of memory performance is largely similar between patients with SCZ and those with RF lesions. These data support tentative arguments that verbal episodic memory deficits in SCZ may be mediated by frontal dysfunction in the right hemisphere.
Murphy, Kelly J.; Troyer, Angela K.; Levine, Brian; Moscovitch, Morris
Amnestic mild cognitive impairment (aMCI) is characterized by decline in anterograde memory as measured by the ability to learn and remember new information. We investigated whether retrograde memory for autobiographical information was affected by aMCI. Eighteen control (age 66–84 years) and 17 aMCI (age 66–84 years) participants described a personal event from each of five periods across the lifespan. These events were transcribed and scored according to procedures that separate episodic (specific happenings) from semantic (general knowledge) elements of autobiographical memory. Although both groups generated protocols of similar length, the composition of autobiographical recall differentiated the groups. The aMCI group protocols were characterized by reduced episodic and increased semantic information relative to the control group. Both groups showed a similar pattern of recall across time periods, with no evidence that the aMCI group had more difficulty recalling recent, rather than remote, life events. These results indicate that episodic and semantic autobiographical memories are differentially affected by the early brain changes associated with aMCI. Reduced autobiographical episodic memories in aMCI may be the result of medial-temporal-lobe dysfunction, consistent with multiple trace theory, or alternatively, could be related to dysfunction of a wider related network of neocortical structures. In contrast, the preservation of autobiographical semantic memories in aMCI suggests neural systems, such as lateral temporal cortex, that support these memories, may remain relatively intact. PMID:18675285
Loucas, Tom; Riches, Nick Greatorex; Charman, Tony; Pickles, Andrew; Simonoff, Emily; Chandler, Susie; Baird, Gillian
Background: The cognitive bases of language impairment in specific language impairment (SLI) and autism spectrum disorders (ASD) were investigated in a novel non-word comparison task which manipulated phonological short-term memory (PSTM) and speech perception, both implicated in poor non-word repetition. Aims: This study aimed to investigate the…
Treweek, Jennifer B.; Sun, Chengzao; Mayorov, Alexander V.; Qi, Longwu; Levy, Coree L.; Roberts, Amanda J.; Dickerson, Tobin J.; Janda, Kim D.
One approach to treating drug abuse uses anti-drug antibodies to immunize subjects against the illicit substance rather than administering therapeutics that target the specific CNS site of action. At present, passive vaccination has recognized efficacy in treating certain gross symptoms of drug misuse, namely motor activation, self-administration, and overdose. However, the potential for antibodies to prevent drug-induced changes involving finer cognitive processes, such as benzodiazepine-associated amnesia, remains unexplored. To address this concept, a flunitrazepam hapten was synthesized and employed in the generation of a panel of high affinity monoclonal antibodies. Anti-flunitrazepam mAb RCA3A3 (Kd,app= 200 nM) was tested in a mouse model of passive immunization and subsequent mole-equivalent challenge with flunitrazepam. Not only was flunitrazepam-induced sedation prevented, but immunization also conferred protection to memory consolidation as assessed through contextual and cued fear conditioning paradigms. These results provide evidence that immunopharmacotherapeutic blockade of drug intoxication also preserves complex cognitive function. PMID:18921991
Maras, P M; Molet, J; Chen, Y; Rice, C; Ji, S G; Solodkin, A; Baram, T Z
The cognitive effects of stress are profound, yet it is unknown if the consequences of concurrent multiple stresses on learning and memory differ from those of a single stress of equal intensity and duration. We compared the effects on hippocampus-dependent memory of concurrent, hours-long light, loud noise, jostling and restraint (multimodal stress) with those of restraint or of loud noise alone. We then examined if differences in memory impairment following these two stress types might derive from their differential impact on hippocampal synapses, distinguishing dorsal and ventral hippocampus. Mice exposed to hours-long restraint or loud noise were modestly or minimally impaired in novel object recognition, whereas similar-duration multimodal stress provoked severe deficits. Differences in memory were not explained by differences in plasma corticosterone levels or numbers of Fos-labeled neurons in stress-sensitive hypothalamic neurons. However, although synapses in hippocampal CA3 were impacted by both restraint and multimodal stress, multimodal stress alone reduced synapse numbers severely in dorsal CA1, a region crucial for hippocampus-dependent memory. Ventral CA1 synapses were not significantly affected by either stress modality. Probing the basis of the preferential loss of dorsal synapses after multimodal stress, we found differential patterns of neuronal activation by the two stress types. Cross-correlation matrices, reflecting functional connectivity among activated regions, demonstrated that multimodal stress reduced hippocampal correlations with septum and thalamus and increased correlations with amygdala and BST. Thus, despite similar effects on plasma corticosterone and on hypothalamic stress-sensitive cells, multimodal and restraint stress differ in their activation of brain networks and in their impact on hippocampal synapses. Both of these processes might contribute to amplified memory impairments following short, multimodal stress. PMID:24589888
Panou, Theodora; Mastorodemos, Vasileios; Papadaki, Efrosyni; Simos, Panagiotis G.; Plaitakis, Andreas
The study investigates primary and secondary verbal memory and motor/executive functions (response inhibition and strategy shifting ability) in multiple sclerosis (MS) patients with clinically isolated syndrome (CIS). We studied 44 CIS patients and compared them to 49 patients with relapsing remitting MS (RR-MS) displaying mild disability and to a large cohort of age- and education level-matched healthy volunteers (n = 230). Results showed that both CIS and RR-MS patients evidenced a disproportionate impairment in the immediate and delayed recall of the second (as compared to the first) of two short narratives of the Logical Memory WMS-III subtest, and reduced performance on the Memory for Digits-Forward. Performance of either group on the executive tasks was not impaired, showing evidence of a reversed speed-accuracy trade-off. Illness duration emerged as a significant predictor of memory and executive task performance. Clinical, psychoemotional, and brain imaging findings were also examined as potential correlates of memory deficits and disease progression among CIS patients. These findings may signify early-onset decline of specific cognitive functions in CIS, which merits regular follow-up assessments and monitoring of psychoemotional adaptation and everyday functioning. PMID:22713377
Hasanein, Parisa; Shahidi, Siamak
Cognitive impairment occurs in diabetes mellitus. Hypericum perforatum has been used in folk medicine to improve mental performance. Here it is hypothesized that chronic treatment with an extract of Hypericum perforatum (6, 12 and 25 mg/kg, p.o.) would have effects on passive avoidance learning (PAL) and memory in control and streptozotocin-induced diabetic rats. Treatments were begun at the onset of hyperglycaemia. PAL was assessed 30 days later. A retention test was done 24 h after training. At the end, the animals were weighed and blood samples were drawn for plasma glucose measurement. Diabetes caused impairment in acquisition and retrieval processes of PAL and memory. Hypericum treatment (12 and 25 mg/kg) improved learning and memory in control rats and reversed learning and memory deficits in diabetic rats. A dose of 6 mg/kg did not affect cognitive function. Hypericum administration did not alter the body weight and plasma glucose levels. Antioxidant properties and cholinergic facilitatory effects of Hypericum may be involved in its nootropic effects. These results show that Hypericum perforatum prevented the deleterious effects of diabetes on PAL and memory. As Hypericum would be free of major side effects compared with other nootropic medications, it may provide a new potential alternative for demented diabetic patients.
Yang, Yang; Jing, Xiao-Peng; Zhang, Shou-Peng; Gu, Run-Xia; Tang, Fang-Xu; Wang, Xiu-Lian; Xiong, Yan; Qiu, Mei; Sun, Xu-Ying; Ke, Dan; Wang, Jian-Zhi; Liu, Rong
Zinc ions highly concentrate in hippocampus and play a key role in modulating spatial learning and memory. At a time when dietary fortification and supplementation of zinc have increased the zinc consuming level especially in the youth, the toxicity of zinc overdose on brain function was underestimated. In the present study, weaning ICR mice were given water supplemented with 15 ppm Zn (low dose), 60 ppm Zn (high dose) or normal lab water for 3 months, the behavior and brain zinc homeostasis were tested. Mice fed high dose of zinc showed hippocampus-dependent memory impairment. Unexpectedly, zinc deficiency, but not zinc overload was observed in hippocampus, especially in the mossy fiber-CA3 pyramid synapse. The expression levels of learning and memory related receptors and synaptic proteins such as NMDA-NR2A, NR2B, AMPA-GluR1, PSD-93 and PSD-95 were significantly decreased in hippocampus, with significant loss of dendritic spines. In keeping with these findings, high dose intake of zinc resulted in decreased hippocampal BDNF level and TrkB neurotrophic signaling. At last, increasing the brain zinc level directly by brain zinc injection induced BDNF expression, which was reversed by zinc chelating in vivo. These results indicate that zinc plays an important role in hippocampus-dependent learning and memory and BDNF expression, high dose supplementation of zinc induces specific zinc deficiency in hippocampus, which further impair learning and memory due to decreased availability of synaptic zinc and BDNF deficit.
Kim, Kijeong; Chung, Eunhee; Kim, Chang-Ju; Lee, Sukho
Regular exercise has been shown to be beneficial to the brain functions, but little is known about the effects of exercise during pregnancy on the long-term memory function of the mothers. The objective of this study was to determine the effects of swimming during pregnancy on long-term memory function in rats on postpartum day 8. We examined the impact of swimming exercise during pregnancy on cell proliferation and apoptotic neuronal cell death in the hippocampus of peripartum rats. The rats were divided into three groups: the control group, the pregnant non-swimming group, and the pregnant swimming group. We found that pregnancy impaired the long-term memory while swimming during pregnancy alleviated the memory impairment. Pregnancy decreased cell proliferation in the dentate gyrus of the hippocampus, but swimming exercise during pregnancy reversed pregnancy-associated decreased cell proliferation back to control level. There was no difference in apoptotic neuronal cell death in the hippocampus among groups. Our results suggest that swimming during pregnancy alleviates pregnancy-associated decrease in memory function of mothers through an increase in cell proliferation in the hippocampus.
Sanders, Ashley F P; Hobbs, Diana A; Stephenson, David D; Laird, Robert D; Beaton, Elliott A
Stress and anxiety have a negative impact on working memory systems by competing for executive resources and attention. Broad memory deficits, anxiety, and elevated stress have been reported in individuals with chromosome 22q11.2 deletion syndrome (22q11.2DS). We investigated anxiety and physiological stress reactivity in relation to visuospatial working memory impairments in 20 children with 22q11.2DS and 32 typically developing (TD) children ages 7 to 16. Children with 22q11.2DS demonstrated poorer working memory, reduced post-stress respiratory sinus arrhythmia recovery, and overall increased levels of cortisol in comparison to TD children. Anxiety, but not physiological stress responsivity, mediated the relationship between 22q11.2DS diagnosis and visuospatial working memory impairment. Findings indicate that anxiety exacerbates impaired working memory in children with 22q11.2DS.
Kida, Kumiko; Tsuji, Tadataka; Tanaka, Susumu; Kogo, Mikihiko
Sufficient oral microelements such as zinc and fully chewing of foods are required to maintain cognitive function despite aging. No knowledge exists about the combination of factors such as zinc deficiency and reduced mastication on learning and memory. Here we show that tooth extraction only in 8-week-old mice did not change the density of glial fibrillary acidic protein-labeled astrocytes in the hippocampus or spatial memory parameters. However, tooth extraction followed by zinc deprivation strongly impaired spatial memory and led to an increase in astrocytic density in the hippocampal CA1 region. The impaired spatial performance in the zinc-deficient only (ZD) mice also coincided well with the increase in the astrocytic density in the hippocampal CA1 region. After switching both zinc-deficient groups to a normal diet with sufficient zinc, spatial memory recovered, and more time was spent in the quadrant with the goal in the probe test in the mice with tooth extraction followed by zinc deprivation (EZD) compared to the ZD mice. Interestingly, we found no differences in astrocytic density in the CA1 region among all groups at 22 weeks of age. Furthermore, the escape latency in a visible probe test at all times was longer in zinc-deficient groups than the others and demonstrated a negative correlation with body weight. No significant differences in escape latency were observed in the visible probe test among the ZD, EZD, and normal-fed control at 4 weeks (CT4w) groups in which body weight was standardized to that of the EZD group, or in the daily reduction in latency between the normal-fed control and CT4w groups. Our data showed that zinc-deficient feeding during a young age impairs spatial memory performance and leads to an increase in astrocytic density in the hippocampal CA1 region and that zinc-sufficient feeding is followed by recovery of the impaired spatial memory along with changes in astrocytic density. The combination of the two factors, zinc deficiency
Gates, George A.; Anderson, Melissa L.; Feeney, M. Patrick; McCurry, Susan M.; Larson, Eric B.
Central auditory function is commonly compromised in people with a diagnosis of Alzheimer's disease (AD) and may precede the onset of clinical dementia by several years. Given that screening for AD in its earliest stages might someday be useful for emerging therapies aimed at limiting progression, we inquired whether central auditory testing might be suitable for identifying people at risk for dementia. To address this question, we performed a battery of behavioral central auditory tests in a cohort of 313 older people enrolled in a dementia surveillance research program. The cohort consisted of three groups: controls without memory loss (N=232), targets with mild memory impairment but without dementia (N=64), and targets with a dementia diagnosis (N=17). The auditory tests were the Synthetic Sentence Identification with Ipsilateral Competing Message (SSI), the Dichotic Sentence Identification test (DSI), the Dichotic Digits Test (DDT), and the Pitch Pattern Sequence (PPS) test. Additional control was provided by electrophysiologic testing to assess the integrity of the primary auditory pathways. The mean score on each central auditory test worsened significantly across the three memory groups even after adjusting for age and peripheral hearing status, being poorest in the pAD group and moderately reduced in the memory-impaired group compared to the mean scores in the control group. Heterogeneity of results was noted in all three groups. The electrophysiologic tests did not differ across the three groups. Central auditory function was affected by mild memory impairment. The Dichotic Sentence Identification in the free report mode appears to be the central auditory test most sensitive to the presence of memory impairment. Although central auditory testing requires specialized equipment and training, the objectivity of these tests is appealing. We recommend that comprehensive auditory testing be considered and further evaluated for its potential value as a baseline
Cook, Peter F; Reichmuth, Colleen; Rouse, Andrew A; Libby, Laura A; Dennison, Sophie E; Carmichael, Owen T; Kruse-Elliott, Kris T; Bloom, Josh; Singh, Baljeet; Fravel, Vanessa A; Barbosa, Lorraine; Stuppino, Jim J; Van Bonn, William G; Gulland, Frances M D; Ranganath, Charan
Domoic acid (DA) is a naturally occurring neurotoxin known to harm marine animals. DA-producing algal blooms are increasing in size and frequency. Although chronic exposure is known to produce brain lesions, the influence of DA toxicosis on behavior in wild animals is unknown. We showed, in a large sample of wild sea lions, that spatial memory deficits are predicted by the extent of right dorsal hippocampal lesions related to natural exposure to DA and that exposure also disrupts hippocampal-thalamic brain networks. Because sea lions are dynamic foragers that rely on flexible navigation, impaired spatial memory may affect survival in the wild.
Newbury, Dianne F.; Winchester, Laura; Addis, Laura; Paracchini, Silvia; Buckingham, Lyn-Louise; Clark, Ann; Cohen, Wendy; Cowie, Hilary; Dworzynski, Katharina; Everitt, Andrea; Goodyer, Ian M.; Hennessy, Elizabeth; Kindley, A. David; Miller, Laura L.; Nasir, Jamal; O'Hare, Anne; Shaw, Duncan; Simkin, Zoe; Simonoff, Emily; Slonims, Vicky; Watson, Jocelynne; Ragoussis, Jiannis; Fisher, Simon E.; Seckl, Jonathon R.; Helms, Peter J.; Bolton, Patrick F.; Pickles, Andrew; Conti-Ramsden, Gina; Baird, Gillian; Bishop, Dorothy V.M.; Monaco, Anthony P.
Specific language impairment (SLI) is a common developmental disorder characterized by difficulties in language acquisition despite otherwise normal development and in the absence of any obvious explanatory factors. We performed a high-density screen of SLI1, a region of chromosome 16q that shows highly significant and consistent linkage to nonword repetition, a measure of phonological short-term memory that is commonly impaired in SLI. Using two independent language-impaired samples, one family-based (211 families) and another selected from a population cohort on the basis of extreme language measures (490 cases), we detected association to two genes in the SLI1 region: that encoding c-maf-inducing protein (CMIP, minP = 5.5 × 10−7 at rs6564903) and that encoding calcium-transporting ATPase, type2C, member2 (ATP2C2, minP = 2.0 × 10−5 at rs11860694). Regression modeling indicated that each of these loci exerts an independent effect upon nonword repetition ability. Despite the consistent findings in language-impaired samples, investigation in a large unselected cohort (n = 3612) did not detect association. We therefore propose that variants in CMIP and ATP2C2 act to modulate phonological short-term memory primarily in the context of language impairment. As such, this investigation supports the hypothesis that some causes of language impairment are distinct from factors that influence normal language variation. This work therefore implicates CMIP and ATP2C2 in the etiology of SLI and provides molecular evidence for the importance of phonological short-term memory in language acquisition. PMID:19646677
Coltman, Robin; Spain, Aisling; Tsenkina, Yanina; Fowler, Jill H; Smith, Jessica; Scullion, Gillian; Allerhand, Mike; Scott, Fiona; Kalaria, Rajesh N; Ihara, Masafumi; Daumas, Stephanie; Deary, Ian J; Wood, Emma; McCulloch, James; Horsburgh, Karen
The integrity of the white matter is critical in regulating efficient neuronal communication and maintaining cognitive function. Damage to brain white matter putatively contributes to age-related cognitive decline. There is a growing interest in animal models from which the mechanistic basis of white matter pathology in aging can be elucidated but to date there has been a lack of systematic behavior and pathology in the same mice. Anatomically widespread, diffuse white matter damage was induced, in 3 different cohorts of C57Bl/6J mice, by chronic hypoperfusion produced by bilateral carotid stenosis. A comprehensive assessment of spatial memory (spatial reference learning and memory; cohort 1) and serial spatial learning and memory (cohort 2) using the water maze, and spatial working memory (cohort 3) using the 8-arm radial arm maze, was conducted. In parallel, a systematic assessment of white matter components (myelin, axon, glia) was conducted using immunohistochemical markers (myelin-associated glycoprotein [MAG], degraded myelin basic protein [dMBP], anti-amyloid precursor protein [APP], anti-ionized calcium-binding adapter molecule [Iba-1]). Ischemic neuronal perikarya damage, assessed using histology (hematoxylin and eosin; H&E), was absent in all shams but was present in some hypoperfused mice (2/11 in cohort 1, 4/14 in cohort 2, and 17/24 in cohort 3). All animals with neuronal perikaryal damage were excluded from further study. Diffuse white matter damage occurred, throughout the brain, in all hypoperfused mice in each cohort and was essentially absent in sham-operated controls. There was a selective impairment in spatial working memory, with all other measures of spatial memory remaining intact, in hypoperfused mice with selective white matter damage. The results demonstrate that diffuse white matter pathology, in the absence of gray matter damage, induces a selective impairment of spatial working memory. This highlights the importance of assessing
Edelstyn, Nicola M J; John, Christopher M; Shepherd, Thomas A; Drakeford, Justine L; Clark-Carter, David; Ellis, Simon J; Mayes, Andrew R
Medicated, non-dementing mild-to-moderate Parkinson's disease (PD) patients usually show recall/recollection impairments but have only occasionally shown familiarity impairments. We aimed to assess two explanations of this pattern of impairment. Recollection typically improves when effortful planning of encoding and retrieval processing is engaged. This depends on prefrontally-dependent executive processes, which are often disrupted in PD. Relative to an unguided encoding and retrieval of words condition (C1), giving suitable guidance at encoding alone (C2) or at encoding and retrieval (C3) should, if executive processes are disrupted, improve PD recollection more than control recollection and perhaps raise it to normal levels. Familiarity, being a relatively automatic kind of memory, whether impaired or intact, should be unaffected by guidance. According to the second explanation, PD deficits are amnesia-like and caused by medial temporal lobe dysfunction and although poorer recollection, which is caused by hippocampal disruption, may be improved by guidance, it should not improve more than control recollection. Familiarity impairment will also occur if the perirhinal cortex is disrupted, but will be unimproved by guidance. Without guidance, recollection/recall was impaired in thirty PD patients relative to twenty-two healthy controls and remained relatively equally impaired when full guidance was provided (C1 vs C3), both groups improving to broadly the same extent. Although impaired, and markedly less so than recollection, familiarity was not improved by guidance in both groups. The patients showed elevated rates of subclinical depressive symptoms, which weakly correlated with recall/recollection in all three conditions. PD executive function was also deficient and correlated with unguided/C1 recollection only. Our results are consistent with a major cause of the patients' recall/recollection impairments being hippocampal disruption, probably exacerbated by
Yang, Yong Ryoul; Song, Seungju; Hwang, Hongik; Jung, Jung Hoon; Kim, Su-Jeong; Yoon, Sora; Hur, Jin-Hoe; Park, Jae-Il; Lee, Cheol; Nam, Dougu; Seo, Young-Kyo; Kim, Joung-Hun; Rhim, Hyewhon; Suh, Pann-Ghill
O-GlcNAcylated proteins are abundant in the brain and are associated with neuronal functions and neurodegenerative diseases. Although several studies have reported the effects of aberrant regulation of O-GlcNAcylation on brain function, the roles of O-GlcNAcylation in synaptic function remain unclear. To understand the effect of aberrant O-GlcNAcylation on the brain, we used Oga+/− mice which have an increased level of O-GlcNAcylation, and found that Oga+/− mice exhibited impaired spatial learning and memory. Consistent with this result, Oga+/− mice showed a defect in hippocampal synaptic plasticity. Oga heterozygosity causes impairment of both long-term potentiation and long-term depression due to dysregulation of AMPA receptor phosphorylation. These results demonstrate a role for hyper-O-GlcNAcylation in learning and memory. PMID:28368052
Jiang, Lizhu; Mao, Rongrong; Zhou, Qixin; Yang, Yuexiong; Cao, Jun; Ding, Yuqiang; Yang, Yuan; Zhang, Xia; Li, Lingjiang; Xu, Lin
Fear is crucial for survival, whereas hypermnesia of fear can be detrimental. Inhibition of the Rac GTPase is recently reported to impair the forgetting of initially acquired memory in Drosophila. Here, we investigated whether inhibition of Rac1 activity in rat hippocampus could contribute to the hypermnesia of contextual fear. We found that spaced but not massed training of contextual fear conditioning caused inhibition of Rac1 activity in the hippocampus and heightened contextual fear. Furthermore, intrahippocampal injection of the Rac1 inhibitor NSC23766 heightened contextual fear in massed training, while Rac1 activator CN04-A weakened contextual fear in spaced training rats. Our study firstly demonstrates that contextual fear memory in rats is actively regulated by Rac1 activity in the hippocampus, which suggests that the forgetting impairment of traumatic events in posttraumatic stress disorder may be contributed to the pathological inhibition of Rac1 activity in the hippocampus.
Narimoto, Tadamasa; Matsuura, Naomi; Takezawa, Tomohiro; Mitsuhashi, Yoshinori; Hiratani, Michio
The authors investigated whether impaired spatial short-term memory exhibited by children with nonverbal learning disabilities is due to a problem in the encoding process. Children with or without nonverbal learning disabilities performed a simple spatial test that required them to remember 3, 5, or 7 spatial items presented simultaneously in random positions (i.e., spatial configuration) and to decide if a target item was changed or all items including the target were in the same position. The results showed that, even when the spatial positions in the encoding and probe phases were similar, the mean proportion correct of children with nonverbal learning disabilities was 0.58 while that of children without nonverbal learning disabilities was 0.84. The authors argue with the results that children with nonverbal learning disabilities have difficulty encoding relational information between spatial items, and that this difficulty is responsible for their impaired spatial short-term memory.
Kelemen, Eduard; Bahrendt, Marie; Born, Jan; Inostroza, Marion
We studied the interaction between glucocorticoid (GC) level and sleep/wake state during memory consolidation. Recent research has accumulated evidence that sleep supports memory consolidation in a unique physiological process, qualitatively distinct from consolidation occurring during wakefulness. This appears particularly true for memories that rely on the hippocampus, a region with abundant expression of GC receptors. Against this backdrop we hypothesized that GC effects on consolidation depend on the brain state, i.e., sleep and wakefulness. Following exploration of two objects in an open field, during 80 min retention periods rats received an intrahippocampal infusion of corticosterone (10 ng) or vehicle while asleep or awake. Then the memory was tested in the hippocampus-dependent object-place recognition paradigm. GCs impaired memory consolidation when administered during sleep but improved consolidation during the wake retention interval. Intrahippocampal infusion of GC or sleep/wake manipulations did not alter novel-object recognition performance that does not require the hippocampus. This work corroborates the notion of distinct consolidation processes occurring in sleep and wakefulnesss, and identifies GCs as a key player controlling distinct hippocampal memory consolidation processes in sleep and wake conditions.
Montgomery, James W.; Evans, Julia L.
Purpose This study investigated the association of 2 mechanisms of working memory (phonological short-term memory [PSTM], attentional resource capacity/allocation) with the sentence comprehension of school-age children with specific language impairment (SLI) and 2 groups of control children. Method Twenty-four children with SLI, 18 age-matched (CA) children, and 16 language- and memory-matched (LMM) children completed a nonword repetition task (PSTM), the competing language processing task (CLPT; resource capacity/allocation), and a sentence comprehension task comprising complex and simple sentences. Results (1) The SLI group performed worse than the CA group on each memory task; (2) all 3 groups showed comparable simple sentence comprehension, but for complex sentences, the SLI and LMM groups performed worse than the CA group; (3) for the SLI group, (a) CLPT correlated with complex sentence comprehension, and (b) nonword repetition correlated with simple sentence comprehension; (4) for CA children, neither memory variable correlated with either sentence type; and (5) for LMM children, only CLPT correlated with complex sentences. Conclusions Comprehension of both complex and simple grammar by school-age children with SLI is a mentally demanding activity, requiring significant working memory resources. PMID:18723601
Bagci, Eyup; Aydin, Emel; Ungureanu, Eugen; Hritcu, Lucian
Anthriscus nemorosa (Bieb.) Sprengel is used for medicinal purposes in traditional medicine around the world, including Turkey. Ethnobotanical studies suggest that Anthriscus essential oil could improve memory in Alzheimer's disease. The current study was hypothesized to investigate the beneficial effects of inhaled Anthriscus nemorosa essential oil on memory, anxiety and depression in scopolamine-treated rats. Anthriscus nemorosa essential oil was administered by inhalation in the doses of 1% and 3% for 21 continuous days and scopolamine (0.7mg/kg) was injected intraperitoneally 30min before the behavioral testing. Y-maze and radial arm-maze tests were used for assessing memory processes. Also, the anxiety and depressive responses were studied by elevated plus-maze and forced swimming tests. As expected, the scopolamine alone-treated rats exhibited the following: decrease the percentage of the spontaneous alternation in Y-maze test, increase the number of working and reference memory errors in radial arm-maze test, decrease of the exploratory activity, the percentage of the time spent and the number of entries in the open arm within elevated plus-maze test and decrease of swimming time and increase of immobility time within forced swimming test. However, dual scopolamine and Anthriscus nemorosa essential oil-treated rats showed significant improvement of memory formation and exhibited anxiolytic- and antidepressant-like effects in scopolamine-treated rats. These results suggest that Anthriscus nemorosa essential oil inhalation can prevent scopolamine-induced memory impairment, anxiety and depression.
Peter, Jessica; Lahr, Jacob; Minkova, Lora; Lauer, Eliza; Grothe, Michel J; Teipel, Stefan; Köstering, Lena; Kaller, Christoph P; Heimbach, Bernhard; Hüll, Michael; Normann, Claus; Nissen, Christoph; Reis, Janine; Klöppel, Stefan
Acetylcholine is critically involved in modulating learning and memory function, which both decline in neurodegeneration. It remains unclear to what extent structural and functional changes in the cholinergic system contribute to episodic memory dysfunction in mild cognitive impairment (MCI), in addition to hippocampal degeneration. A better understanding is critical, given that the cholinergic system is the main target of current symptomatic treatment in mild to moderate Alzheimer's disease. We simultaneously assessed the structural and functional integrity of the cholinergic system in 20 patients with MCI and 20 matched healthy controls and examined their effect on verbal episodic memory via multivariate regression analyses. Mediating effects of either cholinergic function or hippocampal volume on the relationship between cholinergic structure and episodic memory were computed. In MCI, a less intact structure and function of the cholinergic system was found. A smaller cholinergic structure was significantly correlated with a functionally more active cholinergic system in patients, but not in controls. This association was not modulated by age or disease severity, arguing against compensational processes. Further analyses indicated that neither functional nor structural changes in the cholinergic system influence verbal episodic memory at the MCI stage. In fact, those associations were fully mediated by hippocampal volume. Although the cholinergic system is structurally and functionally altered in MCI, episodic memory dysfunction results primarily from hippocampal neurodegeneration, which may explain the inefficiency of cholinergic treatment at this disease stage.
Sumner, Jennifer A; Griffith, James W; Mineka, Susan
Overgeneral autobiographical memory (OGM) is an important cognitive phenomenon in depression, but questions remain regarding the underlying mechanisms. The CaR-FA-X model (Williams et al., 2007) proposes three mechanisms that may contribute to OGM, but little work has examined the possible additive and/or interactive effects among them. We examined two mechanisms of CaR-FA-X: capture and rumination, and impaired executive control. We analysed data from undergraduates (N=109) scoring high or low on rumination who were presented with cues of high and low self-relevance on the Autobiographical Memory Test (AMT). Executive control was operationalised as performance on both the Stroop Colour-Word Task and the Controlled Oral Word Association Test (COWAT). Hierarchical generalised linear modelling was used to predict whether participants would generate a specific memory on a trial of the AMT. Higher COWAT scores, lower rumination, and greater cue self-relevance predicted a higher probability of a specific memory. There was also a rumination×cue self-relevance interaction: Higher (vs lower) rumination was associated with a lower probability of a specific memory primarily for low self-relevant cues. We found no evidence of interactions between these mechanisms. Findings are interpreted with respect to current autobiographical memory models. Future directions for OGM mechanism research are discussed.
Pulopulos, Matias M; Almela, Mercedes; Hidalgo, Vanesa; Villada, Carolina; Puig-Perez, Sara; Salvador, Alicia
Previous studies have shown that stress-induced cortisol increases impair memory retrieval in young people. This effect has not been studied in older people; however, some findings suggest that age-related changes in the brain can affect the relationships between acute stress, cortisol and memory in older people. Our aim was to investigate the effects of acute stress on long-term memory retrieval in healthy older people. To this end, 76 participants from 56 to 76 years old (38 men and 38 women) were exposed to an acute psychosocial stressor or a control task. After the stress/control task, the recall of pictures, words and stories learned the previous day was assessed. There were no differences in memory retrieval between the stress and control groups on any of the memory tasks. In addition, stress-induced cortisol response was not associated with memory retrieval. An age-related decrease in cortisol receptors and functional changes in the amygdala and hippocampus could underlie the differences observed between the results from this study and those found in studies performed with young people.
van Wijngaarden, Edwin; Campbell, James R; Cory-Slechta, Deborah A
Accumulating evidence suggests a link between lead exposure and memory impairment but assessments based on predictive and validated measures are lacking. We conducted a pilot study of 47 healthy subjects 55-67 years of age to examine associations between bone lead levels and 4 tests sensitive to the natural history of Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD). These include three subtests of the Cambridge Neuropsychological Test Automated Battery (delayed match-to-sample, paired associates learning and spatial recognition memory) and the Montreal Cognitive Assessment Test. Bone lead concentrations were measured at the mid-shaft of the tibia and the calcaneus with K X-ray fluorescence. Higher tibial and calcaneal bone lead values were significantly (p<0.05) associated with lower performance levels on delayed match-to-sample and paired associates learning in unadjusted analyses with Spearman rank correlation coefficients of about 0.4. Multiple linear regression analyses (i.e., least-squares means of cognitive test scores across tertiles of lead exposure) adjusted for age, education and smoking status continued to show an association of higher calcaneal lead levels with increasing memory impairments on delayed match-to-sample (p=0.07). As might be expected, additional adjustment for history of hypertension reduced the strength of this association (p=0.19). Given the demonstrated impact of lead exposure on hypertension and the vascular etiology of certain dementias, we speculate that hypertension could play a mediating role in the association between lead exposure and memory impairment.
Du, Chun Nan; Min, A Young; Kim, Hyun Jeong; Shin, Suk Kyung; Yu, Ha Ni; Sohn, Eun Jeong; Ahn, Chang-Won; Jung, Sung Ug; Park, Soo-Hyun; Kim, Mee Ree
Deer bone has been used as a health-enhancing food as well as an antiaging agent in traditional Oriental medicine. Recently, the water extract of deer bone (DBE) showed a neuroprotective action against glutamate or Aβ1-42-induced cell death of mouse hippocampal cells by exerting antioxidant activity through the suppression of MAP kinases. The present study is to examine whether DBE improves memory impairment induced by scopolamine. DBE (50, 100 or 200 mg/kg) was administered orally to mice for 14 days, and then scopolamine (2 mg/kg, i.p.) was administered together with DBE for another 7 days. Memory performance was evaluated in the Morris water maze (MWM) test and passive avoidance test. Also, brain acetylcholinesterase (AChE) and choline acetyltransferase (ChAT) activity, biomarkers of oxidative stress and the loss of neuronal cells in the hippocampus, was evaluated by histological examinations. Administration of DBE significantly restored memory impairments induced by scopolamine in the MWM test (escape latency and number of crossing platform area), and in the passive avoidance test. Treatment with DBE inhibited the AChE activity and increased the ChAT activity in the brain of memory-impaired mice induced by scopolamine. Additionally, the administration of DBE significantly prevented the increase of lipid peroxidation and the decrease of glutathione level in the brain of mice treated with scopolamine. Also, the DBE treatment restored the activities of antioxidant enzymes such as superoxide dismutase, glutathione peroxidase, and glutathione reductase to control the level. Furthermore, scopolamine-induced oxidative damage of neurons in hippocampal CA1 and CA3 regions were prevented by DBE treatment. It is suggested that DBE may be useful for memory improvement through the regulation of cholinergic marker enzyme activities and the suppression of oxidative damage of neurons in the brain of mice treated with scopolamine.
Xian, Yan-Fang; Ip, Siu-Po; Mao, Qing-Qiu; Su, Zi-Ren; Chen, Jian-Nan; Lai, Xiao-Ping; Lin, Zhi-Xiu
Honokiol, a lignan isolated from the bark of Magnolia officinalis, has been reported to ameliorate the learning and memory impairments in senesed (SAMP8) mice. However, whether honokiol could improve scopolamine (SCOP)-induced learning and memory deficits in mice is still unknown. In this study, we aimed to investigate whether honokiol could reverse the SCOP-induced learning and memory impairments in mice and to elucidate its underlying mechanisms of action. Mice were given daily intraperitoneal injection of honokiol (10 and 20mg/kg) for 21 consecutive days. The results showed that honokiol significantly improved spatial learning and memory function (as assessed by the Morris water maze test) in the SCOP-treated mice. In addition, treatment with honokiol significantly decreased the protein and mRNA levels of interleukin (IL)-1β and the activity of acetylcholinesterase (AChE), while significantly increased the protein and mRNA levels of IL-10, and the level of acetylcholine (Ach) in the brain of the SCOP-treated mice. Moreover, honokiol also significantly suppressed the production of prostaglandin E 2 (PGE2) and mRNA expression of cyclooxygenase-2 (COX-2) in the brain of the SCOP-treated mice. Mechanistic investigations revealed that honokiol could markedly reverse the amount of phosphorylated Akt and extracellular regulated kinases 1/2 (ERK1/2) changes in the brain of the SCOP-treated mice. These results amply demonstrated that honokiol could improve learning and memory impairments induced by SCOP in mice, and the protective action may be mediated, at least in part, by inhibition of AChE activity, and amelioration of the neuroinflammatory processes in the SCOP-treated mice.
Williamson, Sally M; Wright, Geraldine A
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.
Xu, Hua; Luo, Xiaobin; Chang, Raymond Chuen-Chung; Liu, Jianjun; Yang, Xifei
Canonical transient receptor potential (TRPC) channels are widely expressed throughout the nervous system whereas their functions remain largely unclear. Here we investigated the effects of TRPC1 deletion on spatial memory ability of mice and the potential intervention by environmental enrichment (EE). Significant spatial memory impairment assessed by conditional fearing test, Y maze test and step-down test in TRPC1 knockout mice was revealed. The behavioral abnormality were attenuated by the treatment of EE. Proteomic analysis by two-dimensional fluorescence difference gel electrophoresis (2D-DIGE) coupled with a matrix-assisted laser desorption/ionisation-time of flight (MALDI-TOF) and tandem mass spectrometry (MS) revealed that TRPC1 deletion caused differential expression of a total of 10 proteins (8 up-regulated and 2 down-regulated) in hippocampus. EE treatment resulted in differential expression of a total of 22 proteins (2 up-regulated and 20 down-regulated) in hippocampus of TRPC1 knockout mice. Among these differentially expressed proteins, the expression of α-internexin and glia maturation factor β (GMF-β), two proteins shown to impair memory, were significantly down-regulated in hippocampus of TRPC1 knockout mice by EE treatment. Taken together, these data suggested that TRPC1 regulated directly or indirectly the expression of multiple proteins, which may be crucial for the maintenance of memory ability, and that EE treatment modulated spatial memory impairment caused by TRPC1 depletion and the mechanisms may involve the modulation of EE on the expression of those dys-regulated proteins such as α-internexin and GMF-β in hippocampus. PMID:27034165
O'Hearn, Kirsten; Courtney, Susan; Street, Whitney; Landau, Barbara
Williams syndrome (WS) is a neurodevelopmental disorder associated with impaired visuospatial representations subserved by the dorsal stream and relatively strong object recognition abilities subserved by the ventral stream. There is conflicting evidence on whether this uneven pattern in WS extends to working memory (WM). The present studies provide a new perspective, testing WM for a single stimulus using a delayed recognition paradigm in individuals with WS and typically developing children matched for mental age (MA matches). In three experiments, participants judged whether a second stimulus 'matched' an initial sample, either in location or identity. We first examined memory for faces, houses and locations using a 5s delay (Experiment 1) and a 2s delay (Experiment 2). We then tested memory for human faces, houses, cat faces, and shoes with a 2s delay using a new set of stimuli that were better controlled for expression, hairline and orientation (Experiment 3). With the 5s delay (Experiment 1), the WS group was impaired overall compared to MA matches. While participants with WS tended to perform more poorly than MA matches with the 2s delay, they also exhibited an uneven profile compared to MA matches. Face recognition was relatively preserved in WS with friendly faces (Experiment 2) but not when the faces had a neutral expression and were less natural looking (Experiment 3). Experiment 3 indicated that memory for object identity was relatively stronger than memory for location in WS. These findings reveal an overall WM impairment in WS that can be overcome under some conditions. Abnormalities in the parietal lobe/dorsal stream in WS may damage not only the representation of spatial location but may also impact WM for visual stimuli more generally.
Williamson, Sally M.; Wright, Geraldine A.
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
Systemic lipopolysaccharide administration impairs retrieval of context-object discrimination, but not spatial, memory: Evidence for selective disruption of specific hippocampus-dependent memory functions during acute neuroinflammation.
Czerniawski, Jennifer; Miyashita, Teiko; Lewandowski, Gail; Guzowski, John F
Neuroinflammation is implicated in impairments in neuronal function and cognition that arise with aging, trauma, and/or disease. Therefore, understanding the underlying basis of the effect of immune system activation on neural function could lead to therapies for treating cognitive decline. Although neuroinflammation is widely thought to preferentially impair hippocampus-dependent memory, data on the effects of cytokines on cognition are mixed. One possible explanation for these inconsistent results is that cytokines may disrupt specific neural processes underlying some forms of memory but not others. In an earlier study, we tested the effect of systemic administration of bacterial lipopolysaccharide (LPS) on retrieval of hippocampus-dependent context memory and neural circuit function in CA3 and CA1 (Czerniawski and Guzowski, 2014). Paralleling impairment in context discrimination memory, we observed changes in neural circuit function consistent with disrupted pattern separation function. In the current study we tested the hypothesis that acute neuroinflammation selectively disrupts memory retrieval in tasks requiring hippocampal pattern separation processes. Male Sprague-Dawley rats given LPS systemically prior to testing exhibited intact performance in tasks that do not require hippocampal pattern separation processes: novel object recognition and spatial memory in the water maze. By contrast, memory retrieval in a task thought to require hippocampal pattern separation, context-object discrimination, was strongly impaired in LPS-treated rats in the absence of any gross effects on exploratory activity or motivation. These data show that LPS administration does not impair memory retrieval in all hippocampus-dependent tasks, and support the hypothesis that acute neuroinflammation impairs context discrimination memory via disruption of pattern separation processes in hippocampus.
Evonuk, Kirsten S; Prabhu, Sumanth D; Young, Martin E; DeSilva, Tara M
The incidence of cognitive impairment in cardiovascular disease (CVD) patients has increased, adversely impacting quality of life and imposing a significant economic burden. Brain imaging of CVD patients has detected changes in the hippocampus, a brain region critical for normal learning and memory. However, it is not clear whether adverse cardiac events or other associated co-morbidities impair cognition. Here, using a murine model of acute myocardial ischemia/reperfusion (I/R), where the coronary artery was occluded for 30min followed by reperfusion, we tested the hypothesis that acute myocardial infarction triggers impairment in cognitive function. Two months following cardiac I/R, behavioral assessments specific for hippocampal cognitive function were performed. Mice subjected to cardiac I/R performed worse in the fear-conditioning paradigm as well as the object location memory behavioral test compared to sham-operated mice. Reactive gliosis was apparent in the hippocampal subregions CA1, CA3, and dentate gyrus 72h post-cardiac I/R as compared with sham, which was sustained two months post-cardiac I/R. Consistent with the inflammatory response, the abundance of doublecortin positive newborn neurons was decreased in the dentate gyrus 72h and 2months post-cardiac I/R as compared with sham. Therefore, we conclude that following acute myocardial infarction, rapid inflammatory responses negatively affect neurogenesis, which may underlie long-term changes in learning and memory.
Knight, Marisa; Mather, Mara
A large body of work reveals that people remember emotionally arousing information better than neutral information. However, previous research reveals contradictory effects of emotional events on memory for neutral events that precede or follow them: in some studies emotionally arousing items impair memory for immediately preceding or following items and in others arousing items enhance memory for preceding items. By demonstrating both emotion-induced enhancement and impairment, Experiments 1 and 2 clarified the conditions under which these effects are likely to occur. The results suggest that emotion-induced enhancement is most likely to occur for neutral items that: (1) precede (and so are poised to predict the onset of) emotionally arousing items, (2) have high attentional weights at encoding, and (3) are tested after a delay period of a week rather than within the same experiment session. In contrast, emotion-induced impairment is most likely to occur for neutral items near the onset of emotional arousal that are overshadowed by highly activated competing items during encoding. PMID:20001121
Hayashi, Masaaki; Tajima, Hirohisa; Hashimoto, Yuichi; Matsuoka, Masaaki
Humanin, a short bioactive peptide, inhibits cell death in a variety of cell-based death models through Humanin receptors in vitro. In vivo, Humanin ameliorates both muscarinic receptor antagonist-induced memory impairment in normal mice and memory impairment in Alzheimer's disease (AD)-relevant mouse models including aged transgenic mice expressing a familial AD-linked gene. Recently, calmodulin-like skin protein (CLSP) has been shown to be secreted from skin tissues, contain a region minimally similar to the core region of Humanin, and inhibit AD-related neuronal death through the heterotrimeric Humanin receptor on the cell surface in vitro. As CLSP is much more potent than Humanin and efficiently transported through blood circulation across the blood-brain barrier to the central nervous system, CLSP is considered as a physiological agonist that binds to the heterotrimeric Humanin receptor and triggers the Humanin-induced signals in central nervous system. However, it remains unknown whether CLSP ameliorates memory impairment in mouse dementia models as Humanin does. In this study, we show that recombinant CLSP, administered intracerebroventricularly or intraperitoneally, ameliorates scopolamine-induced dementia in mice.
Twamley, Elizabeth W; Woods, Steven Paul; Zurhellen, Cynthia H; Vertinski, Mary; Narvaez, Jenille M; Mausbach, Brent T; Patterson, Thomas L; Jeste, Dilip V
Individuals with schizophrenia demonstrate impairment in prospective memory (ProM), which describes the multifaceted ability to execute a future intention. Despite its clear implications for everyday functioning, the neuropsychological substrates and functional correlates of ProM impairment in schizophrenia remain poorly understood. In this study, the Memory for Intentions Screening Test (MIST), a standardized measure of ProM, was administered to 72 outpatients with schizophrenia or schizoaffective disorder as part of a comprehensive neuropsychological and psychiatric research evaluation. Results showed that ProM was positively correlated with standard clinical tests of attention, working memory, processing speed, learning, and executive functioning, but not delayed recall. In the context of multiple neuropsychological predictors, learning ability was the only domain that independently contributed to ProM. Importantly, better ProM was predictive of higher functional capacity (as measured by the UCSD Performance-Based Skills Assessment-Brief Version), above and beyond the variability explained by demographic and disease factors. Analysis of component processes revealed that event-based ProM, as well as no response (i.e., omission) and task substitution errors were the strongest predictors of everyday functioning. Overall, these findings suggest that ProM impairment in schizophrenia is associated with multiple cognitive substrates, particularly episodic learning deficits, and plays an important role in everyday living skills. Studies regarding the potential effectiveness of ProM-based remediation strategies to improve functional outcomes in schizophrenia are indicated.
Baral, Samrat; Cho, Du-Hyong; Pariyar, Ramesh; Yoon, Chi-Su; Chang, Bo-yoon; Kim, Dae-Sung; Cho, Hyoung-Kwon; Kim, Sung Yeon; Oh, Hyuncheol; Kim, Youn-Chul; Kim, Jaehyo; Seo, Jungwon
Myrrh has been used since ancient times for the treatment of various diseases such as inflammatory diseases, gynecological diseases, and hemiplegia. In the present study, we investigated the effects of aqueous extracts of myrrh resin (AEM) on scopolamine-induced memory impairments in mice. AEM was estimated with (2E,5E)-6-hydroxy-2,6-dimethylhepta-2,4-dienal as a representative constituent by HPLC. The oral administration of AEM for 7 days significantly reversed scopolamine-induced reduction of spontaneous alternation in the Y-maze test. In the passive avoidance task, AEM also restored the decreased latency time of the retention trial by scopolamine treatment. In addition, Western blot analysis and Immunohistochemistry revealed that AEM reversed scopolamine-decreased phosphorylation of Akt and extracellular signal-regulated kinase (ERK). Our study demonstrates for the first time that AEM ameliorates the scopolamine-induced memory impairments in mice and increases the phosphorylation of Akt and ERK in the hippocampus of mice brain. These results suggest that AEM has the therapeutic potential in memory impairments. PMID:26635888
Lavner, Yizhar; Rabinowitz, Israel
Objectives: In this study, we investigated whether increasing stimulus duration could improve performance on a test of attention and short-term memory in cognitively impaired individuals. Methods: A computer-generated forward digit span test was administered to 65 patients with mild cognitive impairment or dementia (28 intervention and 37 controls). After point of failure, testing in the intervention group was continued at the same rate, but with an average 150% digit lengthening to 800 ms. Testing of controls was continued using the standard digit span test. Results: In the intervention group, 13/28 (46.4%) improved their digit span test performance, compared to 2/37 (5.4%) in the control group (p = 0.00005). Conclusion: Cognitively impaired elderly participants improved performance on a test of attention and short-term memory, when stimulus duration was increased in proportion to elongation of the finger tap touch-phase previously found in a similar cohort. A possible mechanism for the effect of increased stimulus duration on attention and short-term memory is discussed. PMID:27081485
Cunha, Carla; Angelucci, Andrea; D'Antoni, Angela; Dobrossy, Mate D; Dunnett, Stephen B; Berardi, Nicoletta; Brambilla, Riccardo
In this study we analyzed the effect on behavior of a chronic exposure to brain-derived neurotrophic factor (BDNF), by analysing a mouse line overexpressing BDNF under the alphaCaMKII promoter, which drives the transgene expression exclusively to principal neurons of the forebrain. BDNF transgenic mice and their WT littermates were examined with a battery of behavioral tests, in order to evaluate motor coordination, learning, short and long-term memory formation. Our results demonstrate that chronic BDNF overexpression in the central nervous system (CNS) causes learning deficits and short-term memory impairments, both in spatial and instrumental learning tasks. This observation suggests that a widespread increase in BDNF in forebrain networks may result in adverse effects on learning and memory formation.
Flôres, Maíra F; Martins, Alexandre; Schimidt, Helen L; Santos, Francielli W; Izquierdo, Iván; Mello-Carpes, Pâmela B; Carpes, Felipe P
We investigated the effects of physical exercise and green tea supplementation (associated or not) on biochemical and behavioral parameters in the time course of normal aging. Male Wistar rats aged 9 months were divided into groups: control, physical exercise (treadmill running), and supplemented with green tea while either performing physical exercise or not. A young control group was also studied. Physical exercise and green tea supplementation lasted 3 months. Afterwards, behavioral and biochemical tests were performed. Biochemical measurements revealed differences in antioxidant and oxidant responses in hippocampus, prefrontal cortex and striatum. Behavioral testing showed age-related memory impairments reversed by physical exercise. The association of green tea supplementation and physical exercise did not provide aged rats with additional improvements in memory or brain oxidative markers. Green tea per se significantly decreased reactive oxygen species levels and improved antioxidant defenses although it did not reverse memory deficits associated with normal aging.
Treviño, Samuel; Vázquez-Roque, Rubén A; López-López, Gustavo; Perez-Cruz, Claudia; Moran, Carolina; Handal-Silva, Anhabella; González-Vergara, Enrique; Flores, Gonzalo; Guevara, Jorge; Díaz, Alfonso
Metabolic syndrome (MS) is a serious public health problem, which can promote neuronal alterations in cognitive regions related to memory processes and learning, such as the hippocampus. However, up to now there is no information of a regional segregation of this damage. In this study, we evaluate the MS effect on the neuronal morphology of the hippocampus by a regional segregation approach. Our results demonstrate that 90days of a high-calorie diet altered metabolic energy markers and caused memory impairments, as evaluated by the recognition of novel objects test (NORT). In addition, MS animals showed significant differences in dendritic order, total dendritic length and density of dendritic spines in CA1, CA3 and dentate gyrus (DG) of the hippocampal area compared to control fed rats. Furthermore, the immunoreactivity to synaptophysin (Syp) decreased in the hippocampus of MS animals compared to controls. These results indicate that metabolic alterations induced by MS affect hippocampal plasticity and hippocampal dependent memory processes.
Naderi, Yazdan; Sabetkasaei, Masoumeh; Parvardeh, Siavash; Moini Zanjani, Taraneh
Cerebral ischemia leads to memory impairment that is associated with loss of hippocampal CA1 pyramidal neurons. Neuroinflammation and oxidative stress may be implicated in the pathogenesis of ischemia/reperfusion damage. Minocycline has anti-inflammatory and antioxidant properties. We investigated the neuroprotective effects of minocycline in rats subjected to cerebral ischemia/reperfusion injury. Thirty male rats were divided into three groups: control, sham, and minocycline-pretreated group. Minocycline (40 mg/kg) was injected intraperitoneally immediately before surgery, and then ischemia was induced by occlusion of common carotid arteries for 20 min. Seven days after reperfusion, the Morris water-maze task was used to evaluate memory. Nissl staining was also performed to analyze pyramidal cell damage. We measured the contents of malondialdehyde and proinflammatory cytokines in the hippocampus by the thiobarbituric acid method and enzyme-linked immunosorbent assay, respectively. Microglial activation was also investigated by Iba1 immunostaining. The results showed that pretreatment with minocycline prevented memory impairment induced by cerebral ischemia/reperfusion. Minocycline pretreatment also significantly attenuated ischemia-induced pyramidal cell death and microglial activation in the CA1 region and reduced the levels of malondialdehyde and proinflammatory cytokines (interleukin-1β and tumor necrosis factor-α) in the hippocampus of ischemic rats. Minocycline showed neuroprotective effects on cerebral ischemia-induced memory deficit probably through its anti-inflammatory and antioxidant activities.
Chuhan, Yadvinder S; Taukulis, Harald K
High synaptic concentrations of dopamine and/or norepinephrine can impair the working memory function of the prefrontal cortex and impede attention and learning. Methylphenidate, a dopamine and norepinephrine transporter blocker known to facilitate these cognitive processes at low doses, was hypothesized to interfere with memory storage at doses that may raise concentrations of these neurotransmitters to systemically disruptive levels. In the present experiments, a dose of 10.0mg/kg of this drug was administered to female and male Long-Evans rats using a novel oral administration procedure designed to model the normal mode of delivery to humans. It was found to interfere with single-trial memory acquisition in a delayed object recognition test, a spontaneous learning task that involves no appetitive or aversive motivator. The time that the rats spent in overt exploration of the to-be-remembered objects during the acquisition trial was not affected, suggesting that the drug may have impaired processes of memory formation independently of interference with attention.
Tudor, Jennifer C.; Davis, Emily J.; Peixoto, Lucia; Wimmer, Mathieu E.; van Tilborg, Erik; Park, Alan J.; Poplawski, Shane G.; Chung, Caroline W.; Havekes, Robbert; Huang, Jiayan; Gatti, Evelina; Pierre, Philippe; Abel, Ted
Sleep deprivation is a public health epidemic that causes wide-ranging deleterious consequences, including impaired memory and cognition. Protein synthesis in hippocampal neurons promotes memory and cognition. The kinase complex mammalian target of rapamycin complex 1 (mTORC1) stimulates protein synthesis by phosphorylating and inhibiting the eukaryotic translation initiation factor 4E binding protein 2 (4EBP2). We investigated the involvement of the mTORC1-4EBP2 axis in the molecular mechanisms mediating the cognitive deficits caused by sleep deprivation in mice. Using an in vivo protein translation assay, we found that loss of sleep impaired protein synthesis in the hippocampus. Five hours of sleep loss attenuated both mTORC1-mediated phosphorylation of 4EBP2 and the interaction between eukaryotic initiation factor 4E (eIF4E) and eukaryotic initiation factor 4G (eIF4G) in the hippocampi of sleep-deprived mice. Increasing the abundance of 4EBP2 in hippocampal excitatory neurons prior to sleep deprivation increased the abundance of phosphorylated 4EBP2, restored the amount of eIF4E-eIF4G interaction and hippocampal protein synthesis to that seen in mice that were not sleep-deprived, and prevented the hippocampus-dependent memory deficits associated with sleep loss. These findings collectively demonstrate that 4EBP2-regulated protein synthesis is a critical mediator of the memory deficits caused by sleep deprivation. PMID:27117251
Christoffersen, Gert R J; Simonyi, Agnes; Schachtman, Todd R; Clausen, Bettina; Clement, David; Bjerre, Vicky K; Mark, Louise T; Reinholdt, Mette; Schmith-Rasmussen, Kati; Zink, Lena V B
Metabotropic glutamate receptor subtype 5 (mGlu5) has been implicated in memory processing in some but not all learning tasks. The reason why this receptor is involved in some tasks but not in others remains to be determined. The present experiments using rats examined effects of the mGlu5-antagonist 2-methyl-6-(phenylethynyl)-pyridine (MPEP)--applied systemically i.p. (1-10mg/kg) or bilaterally into the prelimbic cortex (1-10 microg)---on the ability of rats to explore and remember new stimuli. A cross-maze, open field, and object recognition task were used to evaluate exploration and memory and it was found that: (1) locomotion during exploration of spatial environments and exploration time at novel objects were reduced by i.p. but not by prelimbic administration of MPEP, (2) spatial short-term memory was impaired in cross-maze and object discrimination was reduced after both types of administration, (3) long-term retention of spatial conditioning in the cross-maze was inhibited after i.p. applications which (4) also inhibited spontaneous alternation performance during maze-exploration. Reduced exploratory locomotion and exploration time after i.p. injections may have contributed to the observed retention impairments. However, the fact that prelimbic administration of MPEP inhibited retention without reducing exploration shows that memory formation was also impacted directly by prelimbic mGlu5 in both spatial and non-spatial learning.
Valvassori, Samira S; Fortunato, Jucélia J; Gomes, Karin M; Réus, Gislaine Z; Martins, Márcio R; Gavioli, Elaine C; Schetinger, Maria Rosa C; Dal-Pizzol, Felipe; Quevedo, João
Malathion [S-(1,2-dicarbethoxy) ethyl-0,0-dimethyl-phosphorodithioate] is an organophosphorus compound that is widely used as pesticide especially in developing countries. This pesticide affects the central nervous system by inhibiting acetylcholinesterase, leading to an increase of acetylcholine in the synaptic cleft, and subsequent activation of cholinergic muscarinic and nicotinic receptors. In humans, intoxication with organophosphates causes a wide range of neurological symptoms, including memory deficits. The present study was aimed to investigate the effects of the acute (1 h prior the test) and subacute (once a day for 28 days) exposure to malathion at doses of 25, 50, 100 and 150 mg/kg in rats tested in the step-down inhibitory avoidance task, open-field habituation and elevated plus-maze tests. Interestingly, the acute and subacute treatment with malathion impaired aversive-memory in the step-down inhibitory avoidance task, but did not alter the animal performance in the elevated plus-maze and in the habituation to the open-field tests, and neither modified spontaneous locomotion. The activity of acetylcholinesterase enzyme was significantly reduced after subacute, but not acute, treatment with malathion (25, 100 and 150 mg/kg). Our results suggest that malathion impairs aversive-memory retention but not non-associative memory, without affecting anxiety-related behaviors. These findings support the view that the inhibition of acetylcholinesterase enzyme is not correlated with cognitive deficits observed in acute and subacute malathion-treated rats.
Meule, Adrian; Skirde, Ann Kathrin; Freund, Rebecca; Vögele, Claus; Kübler, Andrea
The experience of food craving can lead to cognitive impairments. Experimentally induced chocolate craving exhausts cognitive resources and, therefore, impacts working memory, particularly in trait chocolate cravers. In the current study, we investigated the effects of exposure to food-cues on working memory task performance in a group with frequent and intense (high cravers, n=28) and less pronounced food cravings (low cravers, n=28). Participants performed an n-back task that contained either pictures of high-calorie sweets, high-calorie savory foods, or neutral objects. Current subjective food craving was assessed before and after the task. All participants showed slower reaction times and made more omission errors in response to food-cues, particularly savory foods. There were no differences in task performance between groups. State cravings did not differ between groups before the task, but increased more in high cravers compared to low cravers during the task. Results support findings about food cravings impairing visuo-spatial working memory performance independent of trait cravings. They further show that this influence is not restricted to chocolate, but also applies to high-calorie savory foods. Limiting working memory capacity may be especially crucial in persons who are more prone to high-calorie food-cues and experience such cravings habitually.
Blair, R J R; Frith, U; Smith, N; Abell, F; Cipolotti, L
It is known that the adult visual memory system is fractionable into functionally independent cognitive subsystems, selectively susceptible to brain damage. In addition, there have been hints from studies with individuals with autism that these cognitive subsystems can fractionate developmentally. However, there has been a paucity of systematic investigations. The present study involves the analysis of visual memory of a population of individuals with autism and age- and VIQ-matched comparison individuals. The individuals with autism presented selective impairments in face recognition in comparison to both the age- and VIQ-matched comparison populations. In addition, they were impaired relative to the age-matched comparison group on recognition memory for potential agents (i.e. objects capable of self-propelled motion) whether they were living (cats and horses) or non-living (motorbikes). In contrast, they were selectively superior relative to the VIQ-matched comparison group on recognition memory for such objects as topographical stimuli (buildings) and leaves that clearly do not have agency. The data is interpreted in terms of reduced sensitivity to agency cues in individuals with autism and general information processing capacity.
Mao, Zhengmei; Roman, Gregg; Zong, Lin; Davis, Ronald L.
The GAL4-based Gene-Switch system has been engineered to regulate transgene expression in Drosophila in both time and space. We constructed a Gene-Switch transgene in which Gene-Switch expression is restricted spatially by a defined mushroom body enhancer. This system allows Gene-Switch to be active only in the mushroom bodies and only on administration of the pharmacological Gene-Switch ligand RU486. This line was used to drive the expression of a rutabaga cDNA in otherwise rutabaga mutant flies. Induction of the rutabaga cDNA in the mushroom bodies only during adulthood, or during adulthood along with the larval and pupal developmental stages, corrects the olfactory memory impairment found in rutabaga mutants. Induction of the cDNA only during the larval and pupal stages was inconsequential to performance in olfactory memory tasks. These data indicate that normal rutabaga function must be expressed in adulthood for normal memory and conclusively delimit the time and space expression requirements for correcting the rutabaga memory impairment. Such combined pharmacogenetic regulation of transgene expression now allows this time and space dissection to be made for other behavioral mutants. PMID:14684832
Patarroyo, William E; García-Perez, Milady; Lamprea, Marisol; Múnera, Alejandro; Troncoso, Julieta
This research was aimed at establishing how the absence of active whisking in rats affects acquisition and recovery of spatial memory. The mystacial vibrissae were irreversibly paralyzed by cutting the facial nerve's mandibular and buccal branches bilaterally in the facial nerve lesion group (N=14); control animals were submitted to sham-surgery (N=15). Sham-operated (N=11) and facial nerve-lesioned (N=10) animals were trained (one session, eight acquisition trials) and tested 24h later in a circular Barnes maze. It was found that facial nerve lesioned-animals adequately acquired the spatial task, but had impaired recovery of it when tested 24h after training as compared to control ones. Plasma corticosterone levels were measured after memory testing in four randomly chosen animals of each trained group and after a single training trial in the maze in additional facial nerve-lesioned (N=4) and sham-operated animals (N=4). Significant differences respecting the elevation of corticosterone concentration after either a single training trial or memory testing indicated that stress response was enhanced in facial nerve-lesioned animals as compared to control ones. Increased corticosterone levels during training and testing might have elicited the observed whisker paralysis-induced spatial memory retrieval impairment.
Browning, Philip G F; Baxter, Mark G; Gaffan, David
Neural mechanisms in the temporal lobe are essential for recognition memory. Evidence from human functional imaging and neuropsychology, and monkey neurophysiology and neuropsychology also suggests a role for prefrontal cortex in recognition memory. To examine the interaction of these cortical regions in support of recognition memory we tested rhesus monkeys with prefrontal-inferotemporal (PFC-IT) cortical disconnection on two recognition memory tasks, a "constant negative" task, and delayed nonmatching-to-sample (DNMS). In the constant negative task monkeys were presented with sets of 100 discrimination problems. In each problem one unrewarded object was presented once every day, and became familiar over the course of several days testing. The other, rewarded object was always novel. In this task monkeys learned to avoid the familiar constant negatives and choose the novel objects, so performance on this task is guided by a sense of familiarity for the constant negatives. Following PFC-IT disconnection monkeys were severely impaired at reacquiring the rule (to avoid familiar items) but were subsequently unimpaired at acquiring new constant negative problems, thus displaying intact familiarity recognition. The same monkeys were impaired in the acquisition of the DNMS task, as well as memory for lists of objects. This dissociation between two tests of recognition memory is best explained in terms of our general hypothesis that PFC-IT interactions support the representation of temporally complex events, which is necessary in DNMS but not in constant negative. These findings, furthermore, indicate that stimulus familiarity can be represented in temporal cortex without input from prefrontal cortex.
Stevenson, Erica L.; Caldwell, Heather K.
The function of the CA2 region of the hippocampus is poorly understood. While the CA1 and CA3 regions have been extensively studied, for years the CA2 region has primarily been viewed as a linking area between the two. However, the CA2 region is known to have distinct neurochemical and structural features that are different from the other parts of hippocampus and in recent years it has been suggested that the CA2 region may play a role in the formation and or recall of olfactory-based memories needed for normal social behavior. While this hypothesis has been supported by hippocampal lesion studies that have included the CA2 region, no studies have attempted to specifically lesion the CA2 region of the hippocampus in mice to determine the effects on social recognition memory and olfaction. To fill this knowledge gap, we sought to perform excitotoxic N-methyl-D aspartate (NMDA) lesions of the CA2 region in mice and determine the effects on social recognition memory. We predicted that lesions of the CA2 region would impair social recognition memory. We then went on to test olfaction in CA2 lesioned mice since social memory requires a functional olfactory system. Consistent with our prediction, we found that CA2 lesioned animals have impaired social recognition. These findings are significant because they confirm that the CA2 region of the hippocampus is a part of the neural circuitry that regulates social recognition memory, which may have implications for our understanding of the neural regulation of social behavior across species. PMID:25131412
Crespo, Iris; Santos, Alicia; Valassi, Elena; Pires, Patricia; Webb, Susan M; Resmini, Eugenia
Evaluation of cognitive function in acromegaly has revealed contradictory findings; some studies report normal cognition in patients with long-term cured acromegaly, while others show attention and memory deficits. Moreover, the presence of affective disorders in these patients is common. Our aim was to evaluate memory and decision making in acromegalic patients and explore their relationship with affective disorders like anxiety and depressive symptoms. Thirty-one patients with acromegaly (mean age 49.5 ± 8.5 years, 14 females and 17 males) and thirty-one healthy controls participated in this study. The Iowa Gambling Task (IGT), Rey Auditory Verbal Learning Test, State-Trait Anxiety Inventory, and Beck Depression Inventory-II (BDI-II) were used to evaluate decision making, verbal memory, anxiety, and depressive symptoms, respectively. Acromegalic patients showed impairments in delayed verbal memory (p < 0.05) and more anxiety and depressive symptoms (p < 0.05) than controls. In the IGT, acromegalic patients presented an altered decision-making strategy compared to controls, choosing a lower number of the safer cards (p < 0.05) and higher number of the riskier cards (p < 0.05). Moreover, multiple correlations between anxiety and depressive symptoms and performance in memory and decision making were found. Impaired delayed memory and decision making observed in acromegalic patients are related to anxiety and depressive symptoms. Providing emotional support to the patients could improve their cognitive function. A key clinical application of this research is the finding that depressive symptoms and anxiety are essentially modifiable factors.
Matsumoto, Yukihisa; Matsumoto, Chihiro S.; Takahashi, Toshihumi; Mizunami, Makoto
Age-related memory impairment (AMI) is a common feature and a debilitating phenotype of brain aging in many animals. However, the molecular mechanisms underlying AMI are still largely unknown. The cricket Gryllus bimaculatus is a useful experimental animal for studying age-related changes in learning and memory capability; because the cricket has relatively short life-cycle and a high capability of olfactory learning and memory. Moreover, the molecular mechanisms underlying memory formation in crickets have been examined in detail. In the present study, we trained male crickets of different ages by multiple-trial olfactory conditioning to determine whether AMI occurs in crickets. Crickets 3 weeks after the final molt (3-week-old crickets) exhibited levels of retention similar to those of 1-week-old crickets at 30 min or 2 h after training; however they showed significantly decreased levels of 1-day retention, indicating AMI in long-term memory (LTM) but not in anesthesia-resistant memory (ARM) in olfactory learning of crickets. Furthermore, 3-week-old crickets injected with a nitric oxide (NO) donor, a cyclic GMP (cGMP) analog or a cyclic AMP (cAMP) analog into the hemolymph before conditioning exhibited a normal level of LTM, the same level as that in 1-week-old crickets. The rescue effect by NO donor or cGMP analog injection was absent when the crickets were injected after the conditioning. For the first time, an NO donor and a cGMP analog were found to antagonize the age-related impairment of LTM formation, suggesting that deterioration of NO synthase (NOS) or molecules upstream of NOS activation is involved in brain-aging processes. PMID:27616985
Christodoulou, C.; Melville, P.; Scherl, W.F.; Pai, L.-Y.; Muenz, L.R.; He, D.; Benedict, R.H.B.; Goodman, A.; Rizvi, S.; Schwid, S.R.; Weinstock-Guttman, B.; Westervelt, H.J.; Wishart, H.
Objectives: The goal of this study was to determine if memory would be improved by donepezil as compared to placebo in a multicenter, double-blind, randomized clinical trial (RCT). Methods: Donepezil 10 mg daily was compared to placebo to treat memory impairment. Eligibility criteria included the following: age 18–59 years, clinically definite multiple sclerosis (MS), and performance ≤½ SD below published norms on the Rey Auditory Verbal Learning Test (RAVLT). Neuropsychological assessments were performed at baseline and 24 weeks. Primary outcomes were change on the Selective Reminding Test (SRT) of verbal memory and the participant's impression of memory change. Secondary outcomes included changes on other neuropsychological tests and the evaluating clinician's impression of memory change. Results: A total of 120 participants were enrolled and randomized to either donepezil or placebo. No significant treatment effects were found between groups on either primary outcome of memory or any secondary cognitive outcomes. A trend was noted for the clinician's impression of memory change in favor of donepezil (37.7%) vs placebo (23.7%) (p = 0.097). No serious or unanticipated adverse events attributed to study medication developed. Conclusions: Donepezil did not improve memory as compared to placebo on either of the primary outcomes in this study. Classification of evidence: This study provides Class I evidence which does not support the hypothesis that 10 mg of donepezil daily for 24 weeks is superior to placebo in improving cognition as measured by the SRT in people with MS whose baseline RAVLT score was 0.5 SD or more below average. PMID:21519001
Chaby, Lauren E; Cavigelli, Sonia A; Hirrlinger, Amy M; Lim, James; Warg, Kendall M; Braithwaite, Victoria A
HIGHLIGHTS This study tested the effects of adolescent-stress on adult learning and memory.Adolescent-stressed rats had enhanced reversal learning compared to unstressed rats.Adolescent-stress exposure made working memory more vulnerable to disturbance.Adolescent-stress did not affect adult associative learning or reference memory. Exposure to acute stress can cause a myriad of cognitive impairments, but whether negative experiences continue to hinder individual as they age is not as well understood. We determined how chronic unpredictable stress during adolescence affects multiple learning and memory processes in adulthood. Using male Sprague Dawley rats, we measured learning (both associative and reversal) and memory (both reference and working) starting 110 days after completion of an adolescent-stress treatment. We found that adolescent-stress affected adult cognitive abilities in a context-dependent way. Compared to rats reared without stress, adolescent-stressed rats exhibited enhanced reversal learning, an indicator of behavioral flexibility, but showed no change in associative learning and reference memory abilities. Working memory, which in humans is thought to underpin reasoning, mathematical skills, and reading comprehension, may be enhanced by exposure to adolescent-stress. However, when adolescent-stressed animals were tested after a novel disturbance, they exhibited a 5-fold decrease in working memory performance while unstressed rats continued to exhibit a linear learning curve. These results emphasize the capacity for stress during adolescence to transform the cognitive abilities of adult animals, even after stress exposure has ceased and animals have resided in safe environments for the majority of their lifespans.
Sigwald, Eric L; Genoud, Manuel E; Giachero, Marcelo; de Olmos, Soledad; Molina, Víctor A; Lorenzo, Alfredo
The retrosplenial cortex (RSC) is one of the largest cortical areas in rodents, and is subdivided in two main regions, A29 and A30, according to their cytoarchitectural organization and connectivities. However, very little is known about the functional activity of each RSC subdivision during the execution of complex cognitive tasks. Here, we used a well-established fear learning protocol that induced long-lasting contextual fear memory and showed that during evocation of the fear memory, the expression of early growth response gene 1 was up-regulated in A30, and in other brain areas implicated in fear and spatial memory, however, was down-regulated in A29, including layers IV and V. To search for the participation of A29 on fear memory, we triggered selective degeneration of neurons within cortical layers IV and V of A29 by using a non-invasive protocol that takes advantage of the vulnerability that these neurons have MK801-toxicity and the modulation of this neurodegeneration by testosterone. Application of 5 mg/kg MK801 in intact males induced negligible neuronal degeneration of A29 neurons and had no impact on fear memory retrieval. However, in orchiectomized rats, 5 mg/kg MK801 induced overt degeneration of layers IV-V neurons of A29, significantly impairing fear memory recall. Degeneration of A29 neurons did not affect exploratory or anxiety-related behavior nor altered unconditioned freezing. Importantly, protecting A29 neurons from MK801-toxicity by testosterone preserved fear memory recall in orchiectomized rats. Thus, neurons within cortical layers IV-V of A29 are critically required for efficient retrieval of contextual fear memory.
Chaby, Lauren E.; Cavigelli, Sonia A.; Hirrlinger, Amy M.; Lim, James; Warg, Kendall M.; Braithwaite, Victoria A.
HIGHLIGHTS This study tested the effects of adolescent-stress on adult learning and memory.Adolescent-stressed rats had enhanced reversal learning compared to unstressed rats.Adolescent-stress exposure made working memory more vulnerable to disturbance.Adolescent-stress did not affect adult associative learning or reference memory. Exposure to acute stress can cause a myriad of cognitive impairments, but whether negative experiences continue to hinder individual as they age is not as well understood. We determined how chronic unpredictable stress during adolescence affects multiple learning and memory processes in adulthood. Using male Sprague Dawley rats, we measured learning (both associative and reversal) and memory (both reference and working) starting 110 days after completion of an adolescent-stress treatment. We found that adolescent-stress affected adult cognitive abilities in a context-dependent way. Compared to rats reared without stress, adolescent-stressed rats exhibited enhanced reversal learning, an indicator of behavioral flexibility, but showed no change in associative learning and reference memory abilities. Working memory, which in humans is thought to underpin reasoning, mathematical skills, and reading comprehension, may be enhanced by exposure to adolescent-stress. However, when adolescent-stressed animals were tested after a novel disturbance, they exhibited a 5-fold decrease in working memory performance while unstressed rats continued to exhibit a linear learning curve. These results emphasize the capacity for stress during adolescence to transform the cognitive abilities of adult animals, even after stress exposure has ceased and animals have resided in safe environments for the majority of their lifespans. PMID:26696849
Girelli, Luisa; Semenza, Carlo; Delazer, Margarete
In this study, we modified a classic problem solving task, number series completion, in order to explore the contribution of implicit memory to inductive reasoning. Participants were required to complete number series sharing the same underlying algorithm (e.g., +2), differing in both constituent elements (e.g., 2468 versus 57911) and correct answers (e.g., 10 versus 13). In Experiment 1, reliable priming effects emerged, whether primes and targets were separated by four or ten fillers. Experiment 2 provided direct evidence that the observed facilitation arises at central stages of problem solving, namely the identification of the algorithm and its subsequent extrapolation. The observation of analogous priming effects in a severely amnesic patient strongly supports the hypothesis that the facilitation in number series completion was largely determined by implicit memory processes. These findings demonstrate that the influence of implicit processes extends to higher level cognitive domain such as induction reasoning.
Jaumann, Sarah; Scudelari, Robin; Naug, Dhruba
The energetic cost of cognitive functions can lead to either impairments in learning and memory, or to trade-offs with other functions, when the amount of available energy is limited. However, it has been suggested that, under such conditions, social groups such as honeybees might be able to ward off cognitive impairments in individual bees by adjusting resource allocation at the colony level. Using two complementary experiments, one that tests the effect of learning on subsequent energetic state and survival, and another that tests the effect of energetic state on learning and retention, we show that individual bees pay a significant energetic cost for learning and therefore suffer from significant cognitive deficits under energetic stress. We discuss the implications of such cognitive impairments for the recent observations of bees disappearing from their colonies as well as for social life in general.
McPhee, Grace M; Downey, Luke A; Noble, Anthony; Stough, Con
As the elderly population grows the impact of age associated cognitive decline as well as neurodegenerative diseases such as Alzheimer's disease and dementia will increase. Ageing is associated with consistent impairments in cognitive processes (e.g., processing speed, memory, executive function and learning) important for work, well-being, life satisfaction and overall participation in society. Recently, there has been increased effort to conduct research examining methods to improve cognitive function in older citizens. Cognitive training has been shown to improve performance in some cognitive domains; including memory, processing speed, executive function and attention in older adults. These cognitive changes are thought to be related to improvements in brain connectivity and neural circuitry. Bacopa monnieri has also been shown to improve specific domains of cognition, sensitive to age associated cognitive decline (particularly processing speed and memory). These Bacopa monnieri dependent improvements may be due to the increase in specific neuro-molecular mechanisms implicated in the enhancement of neural connections in the brain (i.e. synaptogenesis). In particular, a number of animal studies have shown Bacopa monnieri consumption upregulates calcium dependent kinases in the synapse and post-synaptic cell, crucial for strengthening and growing connections between neurons. These effects have been shown to occur in areas important for cognitive processes, such as the hippocampus. As Bacopa monnieri has shown neuro-molecular mechanisms that encourage synaptogenesis, while cognitive training enhances brain connectivity, Bacopa monnieri supplementation could theoretically enhance and strengthen synaptic changes acquired through cognitive training. Therefore, the current paper hypothesises that the combination of these two interventions could improve cognitive outcomes, over and above the effects of administrating these interventions independently, as an effective
Gonçalves, Joana; Baptista, Sofia; Olesen, Mikkel V; Fontes-Ribeiro, Carlos; Malva, João O; Woldbye, David P; Silva, Ana P
Methamphetamine (METH) is a psychostimulant drug that causes irreversible brain damage leading to several neurological and psychiatric abnormalities, including cognitive deficits. Neuropeptide Y (NPY) is abundant in the mammalian central nervous system (CNS) and has several important functions, being involved in learning and memory processing. It has been demonstrated that METH induces significant alteration in mice striatal NPY, Y(1) and Y(2) receptor mRNA levels. However, the impact of this drug on the hippocampal NPY system and its consequences remain unknown. Thus, in this study, we investigated the effect of METH intoxication on mouse hippocampal NPY levels, NPY receptors function, and memory performance. Results show that METH increased NPY, Y(2) and Y(5) receptor mRNA levels, as well as total NPY binding accounted by opposite up- and down-regulation of Y(2) and Y(1) functional binding, respectively. Moreover, METH-induced impairment in memory performance and AKT/mammalian target of rapamycin pathway were both prevented by the Y(2) receptor antagonist, BIIE0246. These findings demonstrate that METH interferes with the hippocampal NPY system, which seems to be associated with memory failure. Overall, we concluded that Y(2) receptors are involved in memory deficits induced by METH intoxication.
Lee, Sang Ah; Tucci, Valter; Vallortigara, Giorgio
Research across the cognitive and brain sciences has begun to elucidate some of the processes that guide navigation and spatial memory. Boundary geometry and featural landmarks are two distinct classes of environmental cues that have dissociable neural correlates in spatial representation and follow different patterns of learning. Consequently, spatial navigation depends both on the type of cue available and on the type of learning provided. We investigated this interaction between spatial representation and memory by administering two different tasks (working memory, reference memory) using two different environmental cues (rectangular geometry, striped landmark) in mouse models of human genetic disorders: Prader-Willi syndrome (PWScr(m+/p-) mice, n = 12) and Beta-catenin mutation (Thr653Lys-substituted mice, n = 12). This exploratory study provides suggestive evidence that these models exhibit different abilities and impairments in navigating by boundary geometry and featural landmarks, depending on the type of memory task administered. We discuss these data in light of the specific deficits in cognitive and brain function in these human syndromes and their animal model counterparts.
Lee, Sang Ah; Tucci, Valter; Vallortigara, Giorgio
Research across the cognitive and brain sciences has begun to elucidate some of the processes that guide navigation and spatial memory. Boundary geometry and featural landmarks are two distinct classes of environmental cues that have dissociable neural correlates in spatial representation and follow different patterns of learning. Consequently, spatial navigation depends both on the type of cue available and on the type of learning provided. We investigated this interaction between spatial representation and memory by administering two different tasks (working memory, reference memory) using two different environmental cues (rectangular geometry, striped landmark) in mouse models of human genetic disorders: Prader-Willi syndrome (PWScrm+/p− mice, n = 12) and Beta-catenin mutation (Thr653Lys-substituted mice, n = 12). This exploratory study provides suggestive evidence that these models exhibit different abilities and impairments in navigating by boundary geometry and featural landmarks, depending on the type of memory task administered. We discuss these data in light of the specific deficits in cognitive and brain function in these human syndromes and their animal model counterparts. PMID:28208764
Bellani, Rudy; Luecken, Linda J; Conrad, Cheryl D
We tested the hypothesis that peripubertal anxiety levels are predictive of the detrimental effects of chronic stress on hippocampal-dependent spatial memory. The anxiety levels of peripubertal male Sprague-Dawley rats (43 days old) were characterized using open field and elevated plus mazes, followed by chronic restraint stress for 6 h/day/21 days beginning in young adulthood (75 days). Following chronic stress treatment, rats were tested on the spatial Y-maze using two inter-trial interval levels of difficulty (4 h: 1 day post-chronic stress; 1 min: 2 days post-chronic stress). As expected, all groups displayed intact spatial memory in the less difficult 1 min version of the Y-maze. However, in the 4 h version of the Y-maze, chronically stressed high anxiety rats showed impaired spatial memory, while chronically stressed low anxiety and control (low and high anxiety) rats displayed intact spatial memory. Moreover, a month after chronic stress ended, high anxiety rats had significantly higher basal corticosterone levels than low anxiety rats (control and stress). These results indicate that peripubertal anxiety and chronic stress interact to influence hippocampal-dependent spatial memory in adulthood.
Ebert, Kerry Danahy
Background: Sentence repetition performance is attracting increasing interest as a valuable clinical marker for primary (or specific) language impairment (LI) in both monolingual and bilingual populations. Multiple aspects of memory appear to contribute to sentence repetition performance, but non-verbal memory has not yet been considered. Aims: To…
Aleisa, Abdulaziz M; Alzoubi, Karem H; Gerges, Nashaat Z; Alkadhi, Karim A
The effect of chronic nicotine treatment on chronic psychosocial stress-induced impairment of short-term memory and long-term potentiation (LTP) was determined. An "intruder" stress model was used to induce psychosocial stress for 4-6 wk, during which rats were injected with saline or nicotine (1 mg/kg s.c.) twice a day. The radial arm water maze memory task was used to test hippocampus-dependent spatial memory. Chronic psychosocial stress impaired short-term memory without affecting the learning phase or long-term memory. Concurrent chronic nicotine treatment prevented stress-induced short-term memory impairment. In normal rats chronic nicotine treatment had no effect on learning and memory. Extracellular recordings from the CA1 region of anaesthetized rats showed severe reduction of LTP magnitude in stressed rats, which was normalized in nicotine-treated stressed rats. Nicotine had no effect on LTP in control animals. These results showed that chronic nicotine treatment improved hippocampus-dependent spatial memory and LTP only when impaired by stress.
Sui, Zifang; Qi, Ce; Huang, Yunxiang; Ma, Shufeng; Wang, Xinguo; Le, Guowei; Sun, Jin
Aqueous extracts from Asparagus officinalis L. stems (AEAS) are rich in polysaccharides, gamma-amino butyric acid (GABA), and steroidal saponin. This study was designed to investigate the effects of AEAS on learning, memory, and acetylcholinesterase-related activity in a scopolamine-induced model of amnesia. Sixty ICR mice were randomly divided into 6 groups (n = 10) including the control group (CT), scopolamine group (SC), donepezil group (DON), low, medium, and high dose groups of AEAS (LS, MS, HS; 1.6 mL kg(-1), 8 mL kg(-1), 16 mL kg(-1)). The results showed that 8 mL kg(-1) of AEAS used in this study significantly reversed scopolamine-induced cognitive impairments in mice in the novel object recognition test (P < 0.05) and the Y-maze test (P < 0.05), and also improved the latency to escape in the Morris water maze test (P < 0.05). Moreover, it significantly increased acetylcholine and inhibited acetylcholinesterase activity in the hippocampus, which was directly related to the reduction in learning and memory impairments. It also reversed scopolamine-induced reduction in the hippocampal brain-derived neurotrophic factor (BDNF) and the cAMP response element-binding protein (CREB) mRNA expression. AEAS protected against scopolamine-induced memory deficits. In conclusion, AEAS protected learning and memory function in mice by enhancing the activity of the cholinergic nervous system, and increasing BDNF and CREB expression. This suggests that AEAS has the potential to prevent cognitive impairments in age-related diseases, such as Alzheimer's disease.
Callaway, Jennifer K; Jones, Nigel C; Royse, Alistair G; Royse, Colin F
Post-operative cognitive dysfunction (POCD) predominantly affects the elderly who suffer memory and concentration deficits after anesthesia and surgery. Animal studies have demonstrated anesthetic alone may contribute to POCD but results are variable and little is known about common anesthetics other than isoflurane. The present study investigated dose-dependence of desflurane anesthesia in young adult and aged rats. We hypothesize higher concentrations of desflurane will result in memory impairment in the water maze and that impairment will be worse in aged rats. Effects of anesthesia (1 or 1.5 MAC, 4 h) desflurane, or sham exposure on cognition were investigated in young adult (3 months) and aged (20-24 months) rats at 1, 4, and 12 weeks post-exposure. The Morris water maze was used to assess acquisition and retention of spatial reference memory. Latency to find the hidden platform and swimming speed were compared between treatments. Aged rats showed significant impairment in task acquisition after exposure to 1.5 MAC, but not 1.0 MAC desflurane anesthetic when tested 1 week following exposure. Latency to find the platform and distance travelled were significantly longer in aged rats given 1.5 MAC desflurane (latency: F(1,108) = 19.71, p < 0.0001; distance: F(1,108) = 5.79, p = 0.018). Deficits were not long-lasting and were no longer present at 4 or 12 weeks. In contrast, young adult rats performed equally as well as sham-exposed control rats irrespective of desflurane dose. This study showed the effects of desflurane on learning and memory in the water maze are age and dose dependent and are brief in duration.
Kaczmarczyk, Melissa M; Machaj, Agnieszka S; Chiu, Gabriel S; Lawson, Marcus A; Gainey, Stephen J; York, Jason M; Meling, Daryl D; Martin, Stephen A; Kwakwa, Kristin A; Newman, Andrew F; Woods, Jeffrey A; Kelley, Keith W; Wang, Yanyan; Miller, Michael J; Freund, Gregory G
The prevalence of childhood obesity has risen dramatically and coincident with this upsurge is a growth in adverse childhood psychological conditions including impulsivity, depression, anxiety and attention deficit/hyperactive disorder (ADHD). Due to confounds that exist when determining causality of childhood behavioral perturbations, controversy remains as to whether overnutrition and/or childhood obesity is important. Therefore, we examined juvenile mice to determine if biobehaviors were impacted by a short-term feeding (1-3wks) of a high-fat diet (HFD). After 1wk of a HFD feeding, mouse burrowing and spontaneous wheel running were increased while mouse exploration of the open quadrants of a zero maze, perfect alternations in a Y-maze and recognition of a novel object were impaired. Examination of mouse cortex, hippocampus and hypothalamus for dopamine and its metabolites demonstrated increased homovanillic acid (HVA) concentrations in the hippocampus and cortex that were associated with decreased cortical BDNF gene expression. In contrast, pro-inflammatory cytokine gene transcripts and serum IL-1α, IL-1β, TNF-α and IL-6 were unaffected by the short-term HFD feeding. Administration to mice of the psychostimulant methylphenidate prevented HFD-dependent impairment of learning/memory. HFD learning/memory impairment was not inhibited by the anti-depressants desipramine or reboxetine nor was it blocked in IDO or IL-1R1 knockout mice. In sum, a HFD rapidly impacts dopamine metabolism in the brain appearing to trigger anxiety-like behaviors and learning/memory impairments prior to the onset of weight gain and/or pre-diabetes. Thus, overnutrition due to fats may be central to childhood psychological perturbations such as anxiety and ADHD.
Pace-Schott, Edward F; Spencer, Rebecca M C
Sleep quality and architecture as well as sleep's homeostatic and circadian controls change with healthy aging. Changes include reductions in slow-wave sleep's (SWS) percent and spectral power in the sleep electroencephalogram (EEG), number and amplitude of sleep spindles, rapid eye movement (REM) density and the amplitude of circadian rhythms, as well as a phase advance (moved earlier in time) of the brain's circadian clock. With mild cognitive impairment (MCI) there are further reductions of sleep quality, SWS, spindles, and percent REM, all of which further diminish, along with a profound disruption of circadian rhythmicity, with the conversion to Alzheimer's disease (AD). Sleep disorders may represent risk factors for dementias (e.g., REM Behavior Disorder presages Parkinson's disease) and sleep disorders are themselves extremely prevalent in neurodegenerative diseases. Working memory , formation of new episodic memories, and processing speed all decline with healthy aging whereas semantic, recognition, and emotional declarative memory are spared. In MCI, episodic and working memory further decline along with declines in semantic memory. In young adults, sleep-dependent memory consolidation (SDC) is widely observed for both declarative and procedural memory tasks. However, with healthy aging, although SDC for declarative memory is preserved, certain procedural tasks, such as motor-sequence learning, do not show SDC. In younger adults, fragmentation of sleep can reduce SDC, and a normative increase in sleep fragmentation may account for reduced SDC with healthy aging. Whereas sleep disorders such as insomnia, obstructive sleep apnea, and narcolepsy can impair SDC in the absence of neurodegenerative changes, the incidence of sleep disorders increases both with normal aging and, further, with neurodegenerative disease. Specific features of sleep architecture, such as sleep spindles and SWS are strongly linked to SDC. Diminution of these features with healthy aging
Hasanein, Parisa; Mahtaj, Azam Kazemian
Rosmarinic acid (RA) is a natural phenol that exerts different biological activities, such as antioxidant activity and neuroprotective effects. In this study, we hypothesized that administration of RA (8, 16, and 32 mg/kg, p.o.) for 7 days would effect on scopolamine-induced cognitive dysfunction as an extensively used model of cognitive impairment. The rats were divided into 10 groups. The acquisition trial was done 1h after the last administration of RA. Animals were divided into control, RA (8, 16, and 32 mg/kg) and donepezil (2 mg/kg) treated controls, scopolamine, RA (8, 16, and 32 mg/kg), and donepezil (2 mg/kg) treated scopolamine groups. Memory impairment was induced by scopolamine treatment (1 mg/kg, i.p.) 30 min after the administration of RA, donepezil, or saline. Scopolamine administration caused cognition deficits in the PAL and memory paradigm. While orally RA administration (16 and 32 mg/kg) improved learning and memory in control rats, it reversed learning and memory deficits of scopolamine received groups. Administration of RA at the dose of 8 mg/kg did not alter cognitive function in control and scopolamine treated groups. The combination of anticholinesterase, neuroprotective, and antioxidant properties of RA may all be responsible for the observed effects. These results indicate the beneficial effects of subchronic RA administration in passive avoidance learning and memory in control rats as well as in a pharmacological model of cholinergic deficit which continue to expand the knowledge base in creating new treatment strategies for cognition deficits and dementia. Of course, further studies are warranted for clinical use of RA in the management of demented subjects.
Dun, Changping; Liu, Junqian; Qiu, Fucheng; Wu, Xueda; Wang, Yakun; Zhao, Yongyan; Gu, Ping
Objective Astragalus polysaccharides (APS) are active constituents of Astragalus membranaceus. In this study, we aimed to investigate the effects of APS on memory impairment in a diabetic rat model and their mechanisms. Methods A diabetic model was established in 50 male Wistar rats with streptozotocin intra-peritoneal injection. A blood glucose level higher than 16.7 mmol/L obtained 72 hours after the injection was regarded as a successful diabetic model. The modeled rats were divided into model group, high, medium, and low doses of APS, and piracetam groups (positive control). A group of ten rats without streptozotocin-induced diabetes were used as a normal control. After respective consecutive 8-week treatments, the levels of blood fasting plasma glucose, insulin, hemoglobin A1c, memory performance, hippocampal malondialdehyde, and superoxide dismutase were determined. Results After the 8-week APS treatment, serum fasting plasma glucose, hemoglobin A1c, and insulin levels were decreased compared with those of the model group (P<0.05). Importantly, memory impairment in the diabetic model was reversed by APS treatments. In addition, hippocampal malondialdehyde concentration was lowered, whereas that of superoxide dismutase was higher after APS treatments. Conclusion APS are important active components responsible for memory improvement in rats with streptozotocin-induced diabetes. The potential mechanism of action is associated with the effects of APS on glucose and lipid metabolism, and antioxidative and insulin resistance. APS are constituents of A. membranaceus that are potential candidate therapeutic agents for the treatment of memory deficit in diabetes. PMID:27445477
Darcet, Flavie; Mendez-David, Indira; Tritschler, Laurent; Gardier, Alain M; Guilloux, Jean-Philippe; David, Denis J
Cognitive disturbances are often reported as serious incapacitating symptoms by patients suffering from major depressive disorders (MDDs). Such deficits have been observed in various animal models based on environmental stress. Here, we performed a complete characterization of cognitive functions in a neuroendocrine mouse model of depression based on a chronic (4 weeks) corticosterone administration (CORT). Cognitive performances were assessed using behavioral tests measuring episodic (novel object recognition test, NORT), associative (one-trial contextual fear conditioning, CFC), and visuo-spatial (Morris water maze, MWM; Barnes maze, BM) learning/memory. Altered emotional phenotype after chronic corticosterone treatment was confirmed in mice using tests predictive of anxiety or depression-related behaviors. In the NORT, CORT-treated mice showed a decrease in time exploring the novel object during the test session and a lower discrimination index compared to control mice, characteristic of recognition memory impairment. Associative memory was also impaired, as observed with a decrease in freezing duration in CORT-treated mice in the CFC, thus pointing out the cognitive alterations in this model. In the MWM and in the BM, spatial learning performance but also short-term spatial memory were altered in CORT-treated mice. In the MWM, unlike control animals, CORT-treated animals failed to learn a new location during the reversal phase, suggesting a loss of cognitive flexibility. Finally, in the BM, the lack of preference for the target quadrant during the recall probe trial in animals receiving corticosterone regimen demonstrates that long-term retention was also affected in this paradigm. Taken together, our results highlight that CORT-induced anxio-depressive-like phenotype is associated with a cognitive deficit affecting all aspects of memory tested.
Darcet, Flavie; Mendez-David, Indira; Tritschler, Laurent; Gardier, Alain M.; Guilloux, Jean-Philippe; David, Denis J.
Cognitive disturbances are often reported as serious incapacitating symptoms by patients suffering from major depressive disorders (MDDs). Such deficits have been observed in various animal models based on environmental stress. Here, we performed a complete characterization of cognitive functions in a neuroendocrine mouse model of depression based on a chronic (4 weeks) corticosterone administration (CORT). Cognitive performances were assessed using behavioral tests measuring episodic (novel object recognition test, NORT), associative (one-trial contextual fear conditioning, CFC), and visuo-spatial (Morris water maze, MWM; Barnes maze, BM) learning/memory. Altered emotional phenotype after chronic corticosterone treatment was confirmed in mice using tests predictive of anxiety or depression-related behaviors. In the NORT, CORT-treated mice showed a decrease in time exploring the novel object during the test session and a lower discrimination index compared to control mice, characteristic of recognition memory impairment. Associative memory was also impaired, as observed with a decrease in freezing duration in CORT-treated mice in the CFC, thus pointing out the cognitive alterations in this model. In the MWM and in the BM, spatial learning performance but also short-term spatial memory were altered in CORT-treated mice. In the MWM, unlike control animals, CORT-treated animals failed to learn a new location during the reversal phase, suggesting a loss of cognitive flexibility. Finally, in the BM, the lack of preference for the target quadrant during the recall probe trial in animals receiving corticosterone regimen demonstrates that long-term retention was also affected in this paradigm. Taken together, our results highlight that CORT-induced anxio-depressive-like phenotype is associated with a cognitive deficit affecting all aspects of memory tested. PMID:24822041
Moretti, Paolo; Levenson, Jonathan M; Battaglia, Fortunato; Atkinson, Richard; Teague, Ryan; Antalffy, Barbara; Armstrong, Dawna; Arancio, Ottavio; Sweatt, J David; Zoghbi, Huda Y
Loss-of-function mutations or abnormal expression of the X-linked gene encoding methyl CpG binding protein 2 (MeCP2) cause a spectrum of postnatal neurodevelopmental disorders including Rett syndrome (RTT), nonsyndromic mental retardation, learning disability, and autism. Mice expressing a truncated allele of Mecp2 (Mecp2(308)) reproduce the motor and social behavior abnormalities of RTT; however, it is not known whether learning deficits are present in these animals. We investigated learning and memory, neuronal morphology, and synaptic function in Mecp2(308) mice. Hippocampus-dependent spatial memory, contextual fear memory, and social memory were significantly impaired in Mecp2(308) mutant males (Mecp2(308/Y)). The morphology of dendritic arborizations, the biochemical composition of synaptosomes and postsynaptic densities, and brain-derived neurotrophic factor expression were not altered in these mice. However, reduced postsynaptic density cross-sectional length was identified in asymmetric synapses of area CA1 of the hippocampus. In the hippocampus of symptomatic Mecp2(308/Y) mice, Schaffer-collateral synapses exhibited enhanced basal synaptic transmission and decreased paired-pulse facilitation, suggesting that neurotransmitter release was enhanced. Schaffer-collateral long-term potentiation (LTP) was impaired. LTP was also reduced in the motor and sensory regions of the neocortex. Finally, very early symptomatic Mecp2(308/Y) mice had increased basal synaptic transmission and deficits in the induction of long-term depression. These data demonstrate a requirement for MeCP2 in learning and memory and suggest that functional and ultrastructural synaptic dysfunction is an early event in the pathogenesis of RTT.
Archibald, Lisa M. D.; Joanisse, Marc F.
Purpose: The present study examined the utility of 2 measures proposed as markers of specific language impairment (SLI) in identifying specific impairments in language or working memory in school-age children. Method: A group of 400 school-age children completed a 5-min screening consisting of nonword repetition and sentence recall. A subset of…
Bavin, Edith L.; Wilson, Peter H.; Maruff, Paul; Sleeman, Felicity
Children with Specific language Impairment (SLI) have problems with verbal memory, particularly with tasks that have more processing demands. They also have slower speeds of responding for some tasks. To identify the extent to which young children with SLI would differ in performance from age-matched non-impaired children on a set of spatio-visual…
Salis, Christos; Kelly, Helen; Code, Chris
Background: Aphasia following stroke refers to impairments that affect the comprehension and expression of spoken and/or written language, and co-occurring cognitive deficits are common. In this paper we focus on short-term and working memory impairments that impact on the ability to retain and manipulate auditory-verbal information. Evidence from…
Vugs, Brigitte; Cuperus, Juliane; Hendriks, Marc; Verhoeven, Ludo
We conducted a meta-analysis of the data from studies comparing visuospatial working memory (WM) in children with specific language impairment (SLI) and typically developing (TD) children. The effect sizes of 21 studies (including 32 visuospatial storage tasks and 9 visuospatial central executive (CE) tasks) were identified via computerized database searches and the reference sections of the identified studies. Meta-analyses and moderator analyses were conducted to examine the magnitude of the differences in visuospatial storage and CE, and their relation to the inclusion criteria used for SLI and the age of the children. The results showed significant effect sizes for visuospatial storage (d=0.49) and visuospatial CE (d=0.63), indicating deficits in both components of visuospatial WM in children with SLI. The moderator analyses showed that greater impairment in visuospatial storage was associated with more pervasive language impairment, whereas age was not significant associated with visuospatial WM. The finding of deficits in visuospatial WM suggests domain-general impairments in children with SLI. It raises questions about the language-specificity of a diagnosis of SLI. Careful attention should thus be paid to both verbal and visuospatial WM in clinical practice, and especially in those children with pervasive language impairments.
Morris, Jill K; Vidoni, Eric D; Mahnken, Jonathan D; Montgomery, Robert N; Johnson, David K; Thyfault, John P; Burns, Jeffrey M
Insulin resistance is a risk factor for Alzheimer's disease (AD), although its role in AD etiology is unclear. We assessed insulin resistance using fasting and insulin-stimulated measures in 51 elderly subjects with no dementia (ND; n = 37) and with cognitive impairment (CI; n = 14). CI subjects exhibited either mild CI or AD. Fasting insulin resistance was measured using the homeostatic model assessment of insulin resistance (HOMA-IR). Insulin-stimulated glucose disposal was assessed using the hyperinsulinemic-euglycemic clamp to calculate glucose disposal rate into lean mass, the primary site of insulin-stimulated glucose disposal. Because insulin crosses the blood-brain barrier, we also assessed whether insulin infusion would improve verbal episodic memory compared to baseline. Different but equivalent versions of cognitive tests were administered in counterbalanced order in the basal and insulin-stimulated state. Groups did not differ in age or body mass index. Cognitively impaired subjects exhibited greater insulin resistance as measured at fasting (HOMA-IR; ND: 1.09 [1.1] vs. CI: 2.01 [2.3], p = 0.028) and during the hyperinsulinemic clamp (glucose disposal rate into lean mass; ND: 9.9 (4.5) vs. AD 7.2 (3.2), p = 0.040). Cognitively impaired subjects also exhibited higher fasting insulin compared to ND subjects, (CI: 8.7 [7.8] vs. ND: 4.2 [3.8] μU/mL; p = 0.023) and higher fasting amylin (CI: 24.1 [39.1] vs. 8.37 [14.2]; p = 0.050) with no difference in fasting glucose. Insulin infusion elicited a detrimental effect on one test of verbal episodic memory (Free and Cued Selective Reminding Test) in both groups (p < 0.0001) and no change in performance on an additional task (delayed logical memory). In this study, although insulin resistance was observed in cognitively impaired subjects compared to ND controls, insulin infusion did not improve memory. Furthermore, a significant correlation between HOMA-IR and glucose disposal rate was present only in ND
Saadati, Hakimeh; Esmaeili-Mahani, Saeed; Esmaeilpour, Khadije; Nazeri, Masoud; Mazhari, Shahrzad; Sheibani, Vahid
Inadequate sleep is a common problem in modern societies. It has been previously shown that female rats are more vulnerable to the deleterious effects of sleep deprivation on cognitive functions. Physical exercise has been suggested to attenuate the cognitive impairments induced by sleep deprivation in male rats. The objective of the current study was to investigate the effects of physical exercise on cognitive functions of female rats following paradoxical sleep deprivation. Intact and ovariectomized (OVX) female Wistar rats were used in the present study. The exercise protocol was 4 weeks of treadmill running. The multiple platform method was applied for the induction of 72h paradoxical sleep deprivation and the cognitive function was evaluated using Morris water maze (MWM). Plasma corticosterone level was evaluated in separate groups of study. ANOVA and repeated measures were used to analyze the data and P<0.05 was considered statistically significant. Throughout the investigation, significant learning impairment was observed in sleep-deprived OVX rats compared to the intact and the other OVX groups. Short term memory impairment was observed in both sleep-deprived OVX and intact groups. Physical exercise alleviated the PSD-induced learning and memory impairments in both intact and OVX groups. Corticosterone levels were not statistically significant among the different groups. The results of our study confirmed the negative effects of PSD on cognitive functions in female rats and regular physical exercise seems to protect rats from these effects. Further studies are suggested to be carried out in order to evaluate the possible underlying mechanisms, and also to evaluate the possible interactions between sex hormones and PSD-induced cognitive impairments.
Wang, Rui; Zhang, Yu; Li, Jianguo; Zhang, Ce
β-amyloid (Aβ) deposition is considered partially responsible for cognitive dysfunction in Alzheimer's disease (AD). Recently, resveratrol has been reported to play a potential role as a neuroprotective biofactor by modulating Aβ pathomechanisms, including through anti-neuronal apoptotic, anti-oxidative stress, and anti-neuroinflammatory effects. In addition, SIRT1 has been demonstrated to modulate learning and memory function by regulating the expression of cAMP response binding protein (CREB), which involves in modulating the expression of SIRT1. However, whether resveratrol can alleviate Aβ-induced cognitive dysfunction, whether SIRT1 expression and CREB phosphorylation in the hippocampus are affected by Aβ, and whether resveratrol influences these effects remain unknown. In the present study, we used a hippocampal injection model in rats to investigate the effects of resveratrol on Aβ1-42-induced impairment of spatial learning, memory and synaptic plasticity as well as on alterations of SIRT1 expression and CREB phosphorylation. We found that resveratrol significantly reversed the water maze behavioral impairment and the attenuation of long-term potentiation (LTP) in area CA1 that were induced by hippocampal injection of Aβ1-42. Interestingly, resveratrol also prevented the Aβ1-42-induced reductions in SIRT1 expression and CREB phosphorylation in rat hippocampus. In conclusion, in rats, resveratrol protects neurons against Aβ1-42-induced disruption of spatial learning, memory and hippocampal LTP. The mechanisms underlying the neuroprotective effects may involve rescue of SIRT1 expression and CREB phosphorylation.
Giorgi, Mauro; Pompili, Assunta; Cardarelli, Silvia; Castelli, Valentina; Biagioni, Stefano; Sancesario, Giuseppe; Gasbarri, Antonella
In this work, we report the effect of post-training intraperitoneal administration of zaprinast on rat memory retention in the Morris water maze task that revealed a significant memory impairment at the intermediate dose of 10mg/kg. Zaprinast is capable of inhibiting both striatal and hippocampal PDE activity but to a different extent which is probably due to the different PDE isoforms expressed in these areas. To assess the possible involvement of cyclic nucleotides in rat memory impairment, we compared the effects obtained 30 min after the zaprinast injection with respect to 24h after injection by measuring both cyclic nucleotide levels and PDE activity. As expected, 30 min after the zaprinast administration, we observed an increase of cyclic nucleotides, which returned to a basal level within 24h, with the exception of the hippocampal cGMP which was significantly decreased at the dose of 10mg/kg of zaprinast. This increase in the hippocampal region is the result of a cGMP-specific PDE5 induction, confirmed by sildenafil inhibition, in agreement with literature data that demonstrate transcriptional regulation of PDE5 by cAMP/cGMP intracellular levels. Our results highlight the possible rebound effect of PDE inhibitors.
Anaeigoudari, Akbar; Shafei, Mohammad Naser; Soukhtanloo, Mohammad; Sadeghnia, Hamid Reza; Reisi, Parham; Beheshti, Farimah; Mohebbati, Reza; Mousavi, Seyed Mojtaba; Hosseini, Mahmoud
Inflammation and oxidative stress have important roles in memory impairment. The effect of 7-nitroindazole (7NI) on lipopolysaccharide (LPS)-induced memory impairment was investigated. Rats were used, divided into four groups that were treated as follows: (1) control (saline); (2) LPS; (3) 7NI-LPS; and (4) 7NI before passive avoidance (PA). In the LPS group, the latency for entering the dark compartment was shorter than in the controls (p < 0.01 and p < 0.001); while in the 7NI-LPS group, it was longer than in the LPS group (p < 0.01 and p < 0.001). Malondialdehyde (MDA) and nitric oxide (NO) metabolite concentrations in the brain tissues of the LPS group were higher than in the controls (p < 0.001 and p < 0.05); while in the 7NI-LPS group, they were lower than in the LPS group (p < 0.001 and p < 0.05, respectively). The thiol content in the brain of the LPS group was lower than in the controls (p < 0.001); while in the 7NI-LPS group, it was higher than in the LPS group (p < 0.001). It is suggested that brain tissue oxidative damage and NO elevation have a role in the deleterious effects of LPS on memory retention that are preventable using 7NI.
Zhao, Zhengqing; Li, Yanpeng; Chen, Haiyan; Huang, Liuqing; Zhao, Fei; Yu, Qiang; Xiang, Zhenghua; Zhao, Zhongxin
We aimed to investigate the effects of Xylaria nigripes (XN) extracts on the rapid eye movement sleep deprivation (REMSD)-induced memory impairment, and explore related mechanism. Male Sprague Dawley rats were randomly divided into 6 groups: cage control (CC)-NaCl group; tank control (TC)-NaCl group; sleep deprivation (SD)-NaCl group; CC-XN group; TC-XN group and SD-XN group. The rats were administered with intragastric XN and 0.9% of sodium chloride. SD group rats were deprived of REM sleep for 72 h. Morris water maze (MWM) was used to assess the effects of XN on spatial learning and memory. The expression of cAMP-response element binding protein (CREB) and p-CREB were also investigated in all groups. Result showed rats in SD-NaCl group had significantly longer mean escape latencies in finding the platform as compared to the control rats (p<0.05) in MWM test. The SD-NaCl group spent significantly less time in goal quadrant compared with the SD-XN group. REMSD and XN did not alter CREB expression in the hippocampus, while sleep deprivation resulted in reduced phosphorylation of CREB in the hippocampus, which was reversed by XN. XN mitigates spatial memory impairment induced by REMSD in rat. Phosphorylation of CREB in hippocampus might be one of the mechanisms.
Sun, Jun-Jun; Ren, Qing-Guo; Xu, Lin; Zhang, Zhi-Jun
More than 50% of multiple sclerosis patients develop cognitive impairment. However, the underlying mechanisms are still unclear, and there is no effective treatment. LINGO-1 (LRR and Ig domain containing NOGO receptor interacting protein 1) has been identified as an inhibitor of oligodendrocyte differentiation and myelination. Using the experimental autoimmune encephalomyelitis (EAE) mouse model, we assessed cognitive function at early and late stages of EAE, determined brain expression of myelin basic protein (MBP) and investigated whether the LINGO-1 antibody could restore deficits in learning and memory and ameliorate any loss of MBP. We found that deficits in learning and memory occurred in late EAE and identified decreased expression of MBP in the parahippocampal cortex (PHC) and fimbria-fornix. Moreover, the LINGO-1 antibody significantly improved learning and memory in EAE and partially restored MBP in PHC. Furthermore, the LINGO-1 antibody activated the AKT/mTOR signaling pathway regulating myelin growth. Our results suggest that demyelination in the PHC and fimbria-fornix might contribute to cognitive deficits and the LINGO-1 antibody could ameliorate these deficits by promoting myelin growth in the PHC. Our research demonstrates that LINGO-1 antagonism may be an effective approach to the treatment of the cognitive impairment of multiple sclerosis patients.
Gomez, J L; Luine, V N
Exposure to daily life stressors is associated with increases in anxiety, depression, and overall negative affect. Alcohol or other psychoactive drugs are often used to alleviate stress effects. While females are more than twice as likely to develop mood disorders and are more susceptible to dependency than males, they are infrequently examined. In this study, female rats received no stress/no alcohol control (CON), alcohol alone (ALC), stress alone (STR), or stress plus alcohol (STR+ALC). Stress consisted of restraint for 6h/day/7days, and alcohol was administered immediately following restraint via gastric gavage at a dose of 2.0g/kg. Dependent measures included tests utilizing object recognition (OR), Y-maze, elevated plus maze (EPM), forced swim (FST), blood alcohol content, corticosterone levels, and body weights. ALC, STR+ALC, but not stress alone, impaired memory on OR. All treatments impaired spatial memory on the Y-maze. Anxiety was not affected on the EPM, but rats treated with alcohol or in combination with stress showed increased immobility on the FST, suggestive of alcohol-induced depression. Previously, we found alcohol reversed deleterious effects of stress on memory and mood in males, but current results show that females reacted negatively when the two treatments were combined. Thus, responses to alcohol, stress and their combination suggest that sex specific treatments are needed for stress-induced behavioral changes and that self-medicating with alcohol to cope with stress maybe deleterious in females.
Kim, Lenise Jihe; Martinez, Denis; Fiori, Cintia Zappe; Baronio, Diego; Kretzmann, Nélson Alexandre; Barros, Helena Maria Tannhauser
We investigated the effect of intermittent hypoxia, mimicking sleep apnea, on axonal integrity, blood-brain barrier permeability, and cognitive function of mice. Forty-seven C57BL mice were exposed to intermittent or sham hypoxia, alternating 30s of progressive hypoxia and 30s of reoxigenation, during 8h/day. The axonal integrity in cerebellum was evaluated by transmission electron microscopy. Short- and long-term memories were assessed by novel object recognition test. The levels of endothelin-1 were measured by ELISA. Blood-brain barrier permeability was quantified by Evans Blue dye. After 14 days, animals exposed to intermittent hypoxia showed hypomyelination in cerebellum white matter and higher serum levels of endothelin-1. The short and long-term memories in novel object recognition test was impaired in the group exposed to intermittent hypoxia as compared to controls. Blood-brain barrier permeability was similar between the groups. These results indicated that hypomyelination and impairment of short- and long-term working memories occurred in C57BL mice after 14 days of intermittent hypoxia mimicking sleep apnea.
Soares, Juliana Carlota Kramer; Oliveira, Maria Gabriela Menezes; Ferreira, Tatiana Lima
Extensive research has shown that the hippocampus and striatum have dissociable roles in memory and are necessary for place and response learning, respectively. Additional evidence indicates that muscarinic cholinergic receptors in the hippocampus and striatum exert an important role in the modulation of these memory systems. In our experiments, we assessed whether intact hippocampal and striatal muscarinic cholinergic transmission may be essential and/or necessary for place and response learning. We addressed these questions using administration of the muscarinic receptor antagonist, scopolamine, on both place and response learning in a food-rewarded T-maze task. The administration of scopolamine (15 μg or 30 μg) directly into the dorsal hippocampus impaired the performance of rats subjected to both place and cue-rich response version of the task, but did not affect the response version, when the task was performed under cue-poor conditions. However, the administration of scopolamine in the dorsolateral striatum impaired the cue-poor response version of the T-maze task without interfering with the place version or cue-rich response version. Taken together, these results indicate that activation of muscarinic cholinergic receptors in the hippocampus and striatum facilitate the use of different strategies of learning, thus strengthening the hypothesis of multiple memory systems. Additionally, these results emphasize the importance of the environmental conditions under which tasks are performed.
Fogel, Stuart M; Albouy, Genevieve; Vien, Catherine; Popovicci, Romana; King, Bradley R; Hoge, Rick; Jbabdi, Saad; Benali, Habib; Karni, Avi; Maquet, Pierre; Carrier, Julie; Doyon, Julien
Behavioral studies indicate that older adults exhibit normal motor sequence learning (MSL), but paradoxically, show impaired consolidation of the new memory trace. However, the neural and physiological mechanisms underlying this impairment are entirely unknown. Here, we sought to identify, through functional magnetic resonance imaging during MSL and electroencephalographic (EEG) recordings during daytime sleep, the functional correlates and physiological characteristics of this age-related motor memory deficit. As predicted, older subjects did not exhibit sleep-dependent gains in performance (i.e., behavioral changes that reflect consolidation) and had reduced sleep spindles compared with young subjects. Brain imaging analyses also revealed that changes in activity across the retention interval in the putamen and related brain regions were associated with sleep spindles. This change in striatal activity was increased in young subjects, but reduced by comparison in older subjects. These findings suggest that the deficit in sleep-dependent motor memory consolidation in elderly individuals is related to a reduction in sleep spindle oscillations and to an associated decrease of activity in the cortico-striatal network.
Zhu, Guoqi; Briz, Victor; Seinfeld, Jeff; Liu, Yan; Bi, Xiaoning; Baudry, Michel
Recent studies indicate that calpain-1 is required for the induction of long-term potentiation (LTP) elicited by theta-burst stimulation in field CA1 of hippocampus. Here we determined the contribution of calpain-1 in another type of synaptic plasticity, the long-term depression (LTD) elicited by activation of type-I metabotropic glutamate receptors (mGluR-LTD). mGluR-LTD was associated with calpain-1 activation following T-type calcium channel opening, and resulted in the truncation of a regulatory subunit of PP2A, B56α. This signaling pathway was required for both the early and late phase of Arc translation during mGluR-LTD, through a mechanism involving mTOR and ribosomal protein S6 activation. In contrast, in hippocampal slices from calpain-1 knock-out (KO) mice, application of the mGluR agonist, DHPG, did not result in B56α truncation, increased Arc synthesis and reduced levels of membrane GluA1-containing AMPA receptors. Consistently, mGluR-LTD was impaired in calpain-1 KO mice, and the impairment could be rescued by phosphatase inhibitors, which also restored Arc translation in response to DHPG. Furthermore, calpain-1 KO mice exhibited impairment in fear memory extinction to tone presentation. These results indicate that calpain-1 plays a critical role in mGluR-LTD and is involved in many forms of synaptic plasticity and learning and memory. PMID:28202907
Zhu, Guoqi; Briz, Victor; Seinfeld, Jeff; Liu, Yan; Bi, Xiaoning; Baudry, Michel
Recent studies indicate that calpain-1 is required for the induction of long-term potentiation (LTP) elicited by theta-burst stimulation in field CA1 of hippocampus. Here we determined the contribution of calpain-1 in another type of synaptic plasticity, the long-term depression (LTD) elicited by activation of type-I metabotropic glutamate receptors (mGluR-LTD). mGluR-LTD was associated with calpain-1 activation following T-type calcium channel opening, and resulted in the truncation of a regulatory subunit of PP2A, B56α. This signaling pathway was required for both the early and late phase of Arc translation during mGluR-LTD, through a mechanism involving mTOR and ribosomal protein S6 activation. In contrast, in hippocampal slices from calpain-1 knock-out (KO) mice, application of the mGluR agonist, DHPG, did not result in B56α truncation, increased Arc synthesis and reduced levels of membrane GluA1-containing AMPA receptors. Consistently, mGluR-LTD was impaired in calpain-1 KO mice, and the impairment could be rescued by phosphatase inhibitors, which also restored Arc translation in response to DHPG. Furthermore, calpain-1 KO mice exhibited impairment in fear memory extinction to tone presentation. These results indicate that calpain-1 plays a critical role in mGluR-LTD and is involved in many forms of synaptic plasticity and learning and memory.
Erickson, Molly A; Hahn, Britta; Leonard, Carly J; Robinson, Benjamin; Gray, Brad; Luck, Steven J; Gold, James
The cognitive impairments associated with schizophrenia have long been known to involve deficits in working memory (WM) capacity. To date, however, the causes of WM capacity deficits remain unknown. The present study examined selective attention impairments as a putative contributor to observed capacity deficits in this population. To test this hypothesis, we used an experimental paradigm that assesses the role of selective attention in WM encoding and has been shown to involve the prefrontal cortex and the basal ganglia. In experiment 1, participants were required to remember the locations of 3 or 5 target items (red circles). In another condition, 3-target items were accompanied by 2 distractor items (yellow circles), which participants were instructed to ignore. People with schizophrenia (PSZ) exhibited significant impairment in memory for the locations of target items, consistent with reduced WM capacity, but PSZ and healthy control subjects did not differ in their ability to filter the distractors. This pattern was replicated in experiment 2 for distractors that were more salient. Taken together, these results demonstrate that reduced WM capacity in PSZ is not attributable to a failure of filtering irrelevant distractors.
Alikatte, Kanaka Latha; Akondi, Butchi Raju; Yerragunta, Venu Gopal; Veerareddy, Prabhakar Reddy; Palle, Suresh
We evaluated the Antiamnesic effects of methanolic extract of Syzygium cumini (MESC) on spatial memory impairments induced by scopolamine (1 mg/kg, i.p.), a muscarinic antagonist, using the Radial arm maze, Morris water maze, learned helpless ness tests. Effect of MESC was evaluated and compared to standard drug, piracetam (200 mg/kg, i.p.). The MESC significantly (p<0.05) improved the impairment of short term or working memory induced by scopolamine in the Radial arm maze test, and significantly (p<0.05) reversed cognitive impairments in rats as measured by the learned helplessness test. In addition, MESC decreased escape latencies in the Morris water maze test. The activity of acetylcholinesterase in the brain was inhibited significantly (p<0.05) by treatment with MESC to a level similar to that observed in rats treated with piracetam. Moreover treatment with MESC (200 and 400 mg/kg, p.o.) to scopolamine induced rats significantly (p<0.05) decreased TBARS levels which was accompanied by an increase in the activities of SOD and Catalase. MESC has dose dependent effect and 400 mg/kg dose shown more prominent results when compared to 200 mg/kg dose of MESC. These results indicate that MESC may exert anti-amnesic activity via inhibition of acetylcholinesterase and antioxidant mechanisms in the brain.
Giménez Castejón, Domingo; Dudekova, Miriama; Gómez Gallego, Maria; Lajara Blesa, Jerónimo
ABSTRACT Alzheimer’s disease (AD) is the main cause of dementia worldwide, which implies an important socioeconomic problem in developed countries. Efforts to find biomarkers to diagnose AD have been intensified, especially, to detect cognitive impairment in its early stages, also known as mild cognitive impairment (MCI). Besides, there are individuals referring memory loss that is unnoticeable in the family environment and presenting normal neuropsychological tests. The former patients are included in a clinical picture that has been recently called subjective memory complaints (SMC). To achieve an early diagnosis, optical coherence tomography (OCT) has been used to measure macular thickness in patients diagnosed with MCI (supported by neuropsychological tests) and SMC (not based on neuropsychological battery). Statistically significant differences have been found in the macular thickness of the control group (274.96 ± 17.61 µm) and for both MCI (259.48 ± 22.39 µm) and SMC (261.45 ± 24.26 µm) patients. In the near future, OCT could become a reliable biomarker and a useful tool for AD screening as well as for the monitoring of the cognitive impairment associated with AD. PMID:27928377
Ramezani, Matin; Darbandi, Niloufar; Khodagholi, Fariba; Hashemi, Azam
There is currently no treatment for effectively slowing the progression of Alzheimer's disease, so early prevention is very important. Numerous studies have shown that flavonoids can improve memory impairment. The present study investigated the effects of myricetin, a member of the flavonoids, on intracerebroventricular streptozotocin induced neuronal loss and memory impairment in rat models of Alzheimer's disease. Myricetin at 5 or 10 mg/kg was intraperitoneally injected into rats over 21 days. Control rats were treated with 10 mL/kg saline. Behavioral test (the shuttle box test) was performed on day 22 to examine learning and memory in rats. Immediately after that, hematoxylin-eosin staining was performed to observe the morphological change in hippocampal CA3 pyramidal neurons. Myricetin greatly increased the number of hippocampal CA3 pyramidal neurons and improved learning and memory impairments in rats with Alzheimer's disease. These findings suggest that myricetin is beneficial for treatment of Alzheimer's disease. PMID:28197195
Braida, Daniela; Donzelli, Andrea; Martucci, Roberta; Capurro, Valeria; Sala, Mariaelvina
The effects of salvinorin A (Salvia divinorum principal ingredient), a potent κ-opioid natural hallucinogen, on learning and memory were investigated. Wistar rats were tested in the 8-arm radial maze, for object recognition and passive avoidance tasks for spatial, episodic, and aversive memory. Attention was assessed using a latent inhibition task. Salvinorin A (80-640 μg/kg subcutaneous [sc]) did not affect short-term memory, but it impaired spatial long-term memory. Episodic and aversive memories were impaired by salvinorin A (160-640 μg/kg). Memory impairment was blocked by the selective κ-opioid receptor antagonist, nor-binaltorphimine ([nor-B]; 0.5-1 mg/kg, intraperitoneal [ip]). Salvinorin A (160 μg/kg) disrupted latent inhibition, after LiCl treatment, such as reduced sucrose intake, suggesting an attention would result in an impairment of cognitive behavior. These findings demonstrate for the first time that salvinorin A has deleterious effects on learning and memory, through a κ-opioid receptor mechanism.
Cook, Sarah E.; Sisco, Shannon M.; Marsiske, Michael
While driving is a complex task, it becomes relatively automatic over time although unfamiliar situations require increased cognitive effort. Much research has examined driving risk in cognitively impaired elders and found little effect. This study assessed whether mildly memory impaired elders made disproportionate errors in driving or story recall, under simultaneous simulated driving and story recall. Forty-six healthy (61% women; mean age = 76.4) and 15 memory impaired (66% women, mean age = 79.4) elders participated. Cognitive status was determined by neuropsychological performance. Results showed that during dual-task conditions, participants stayed in lane more, and recalled stories more poorly, than when they did the tasks separately. Follow-up analysis revealed that verbatim recall, in particular, was reduced while driving for healthy participants. While memory impaired participants performed more poorly than healthy controls on both tasks, cognitive status was not associated with greater dual-task costs when driving and story recall were combined. PMID:23043546
Ferguson, Deveroux; Sapolsky, Robert
It is well established that mineralocorticoid receptors (MRs) and glucocorticoid receptors (GRs) influence hippocampal-dependent spatial memory. MRs are saturated in the presence of low corticosterone (CORT) levels; consequently receptor protein levels play a rate-limiting role in regulating the positive effects of MR-mediated gene transcription. In this study, viral vector-mediated transgene expression was used to simultaneously manipulate both MR and GR signaling. This approach allowed us to investigate the effects of spatially restricted overexpression of MR and a negative transdominant GR (TD) in the dentate gyrus (DG) subfield of the hippocampus, on short term and long term spatial memory in animals overexpressing one copy of MR or TD, two copies of MR ("MR/MR"), or one copy of each ("MR/TD"). Expression of transgenes did not influence the acquisition (learning) phase of the Morris water maze task. However, we found an overall enhancing effect of MR/MR expression on short term memory performance. In addition, rats expressing TD and MR/TD blocked the high CORT-induced impairments on long term spatial memory retrieval. These findings illustrate the potential beneficial effects of increasing MR signaling or decreasing GR signaling to enhance specific aspects of cognitive function.
Hashemi Nosrat Abadi, T; Vaghef, L; Babri, S; Mahmood-Alilo, M; Beirami, M
Chronic ethanol consumption is often accompanied by numerous cognitive deficits and may lead to long-lasting impairments in spatial learning and memory. The aim of the present study was to evaluate the therapeutic potential of regular treadmill exercise on hippocampal-dependent memory in ethanol-treated rats. Spatial memory was tested in a Morris Water Maze task. Adult male Wistar rats were exposed to ethanol (4 g/kg, 20% v/v for 4 weeks) and effects of three exercise protocols (pre-ethanol, post-ethanol and pre-to-post-ethanol treatment) were examined. Results showed that ethanol exposure resulted in longer escape latencies during the acquisition phase of the Morris Water Maze task. Moreover, all three exercise protocols significantly decreased the latency to locate the hidden platform. During the probe trial, ethanol led to decreased time spent in the target quadrant. In contrast, performance on the probe trial was significantly better in the rats that had done the post- and pre-to-post-ethanol, but not pre-ethanol, exercises. These findings suggest that treadmill running can attenuate the adverse effects of chronic ethanol exposure on spatial memory, and may serve as a non-pharmacological alcohol abuse treatment.
Gigi, Ariela; Babai, Reuven; Penker, Avichen; Hendler, Talma; Korczyn, Amos D
Mild cognitive impairment (MCI) is considered as a potential transitional state between normal aging and dementia. Studies addressing semantic memory in patients with incipient dementia and MCI show inconsistent results. In the current report we focused on MCI and examined memory performance (semantic, episodic, and working memory) in addition to structural and functional magnetic resonance imaging (fMRI) measurements. We studied 6 MCI, 6 normal controls, and 4 Alzheimer disease (AD) patients. MCI participants demonstrated normal semantic memory performance while fMRI examination revealed distinct patterns of activations between MCI and normal aged subjects. According to our previous study, time courses were taken from parietal, dorsolateral-prefrontal-cortex (DLPFC), hippocampal formation, and fusiform gyri. A small number of activated voxels in parietal regions were depicted in MCI participants and were correlated with structural changes in this region. In contrast, significantly higher activation (intensity and number of voxels) was observed in DLPFC of MCI subjects. The overactivity seen in DLPFC of MCI may represent a compensatory mechanism that enables them to perform normally. These preliminary results suggest that functional imaging may be useful for early diagnosis of dementia and call to develop reliable tests and criteria that will enable using such methods clinically.
Buchanan, Tony W; Tranel, Daniel; Adolphs, Ralph
Stress can enhance or impair memory performance. Both cortisol release and sympathetic nervous system responses have been implicated in these differential effects. Here we investigated how memory retrieval might be affected by stress-induced cortisol release, independently of sympathetic nervous system stress responses. Thirty-two healthy participants (16 women) learned emotionally arousing and neutral words. One hour later, half of the participants underwent a stressor (cold pressor test) and the other half, a control warm water exposure, both followed by a delayed free recall task. The stressed participants were split into those who did (responders, N = 8) and those who did not (nonresponders, N = 6) show a cortisol response. Both responders and nonresponders showed comparable sympathetic nervous system activity (skin conductance level) during the cold pressor. The cortisol responders recalled significantly fewer words compared to nonresponders, and compared to control participants; this effect was most pronounced for moderately arousing words (compared to highly arousing and neutral words). These results suggest that individual differences in cortisol reactivity affect memory retrieval performance, and help to explain the differential effects of stress on memory.
Waring, Jill D; Seiger, Ashley N; Solomon, Paul R; Budson, Andrew E; Kensinger, Elizabeth A
The present study examined memory accuracy and confidence for personal and public event details of the 2008 presidential election in healthy older adults and those with mild cognitive impairment (MCI). Participants completed phone interviews within a week after the election and after a 10-month delay. MCI patients and healthy older adults had comparable emotional reactions to learning the outcome of the election, with most people finding it to be a positive experience. After the delay period, details about the election were better remembered by all participants than a less emotionally arousing comparison event. However, MCI patients had more difficulty than healthy older adults correctly recalling details of public information about the election, although often the MCI patients could recognise the correct details. This is the first study to show that MCI patients' memory can benefit from emotionally arousing positive events, complementing the literature demonstrating similar effects for negative events.
Zhao, Yanhua; Huang, Lili; Xu, Huan; Wu, Guangxi; Zhu, Mengyi; Tian, Jie; Wang, Hao; Yu, Weifeng
Postoperative cognitive dysfunction (POCD) increases morbidity and mortality after surgery. But the underlying mechanism is not clear yet. While age is now accepted as the top one risk factor for POCD, results from studies investigating postoperative cognitive functions in adults have been controversial, and data about the very young adult individuals are lacking. The present study investigated the spatial reference memory, IL-1β, IL-6, and microglia activation changes in the hippocampus in 2-month-old mice after anesthesia and surgery. We found that hippocampal IL-1β and IL-6 increased at 6 hours after surgery. Microglia were profoundly activated in the hippocampus 6 to 24 hours after surgery. However, no significant behavior changes were found in these mice. These results indicate that although anesthesia and surgery led to neuroinflammation, the latter was insufficient to impair the spatial reference memory of young adult mice. PMID:27956760
Waring, Jill D.; Seiger, Ashley N.; Solomon, Paul R.; Budson, Andrew E.; Kensinger, Elizabeth A.
Objective The present study examined memory accuracy and confidence for personal and public event details of the 2008 Presidential election in healthy older adults and those with Mild Cognitive Impairment (MCI). Method Participants completed phone interviews within a week after the election and after a 10-month delay. Results MCI patients and healthy older adults had comparable emotional reactions to learning the outcome of the election, with most people finding it to be a positive experience. After the delay period, details about the election were better remembered by all participants than a less emotionally arousing comparison event. However, MCI patients had more difficulty than healthy older adults correctly recalling details of public information about the election, although often the MCI patients could recognize the correct details. Conclusion This is the first study to show that MCI patients’ memory can benefit from emotionally arousing positive events, complementing the literature demonstrating similar effects for negative events. PMID:24533684
Wheelan, Nicola; Webster, Scott P.; Kenyon, Christopher J.; Caughey, Sarah; Walker, Brian R.; Holmes, Megan C.; Seckl, Jonathan R.; Yau, Joyce L.W.
High glucocorticoid levels induced by stress enhance the memory of fearful events and may contribute to the development of anxiety and posttraumatic stress disorder. In contrast, elevated glucocorticoids associated with ageing impair spatial memory. We have previously shown that pharmacological inhibition of the intracellular glucocorticoid-amplifying enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) improves spatial memory in aged mice. However, it is not known whether inhibition of 11β-HSD1 will have any beneficial effects on contextual fear memories in aged mice. Here, we examined the effects of UE2316, a selective 11β-HSD1 inhibitor which accesses the brain, on both spatial and contextual fear memories in aged mice using a vehicle-controlled crossover study design. Short-term UE2316 treatment improved spatial memory in aged mice, an effect which was reversed when UE2316 was substituted with vehicle. In contrast, contextual fear memory induced by foot-shock conditioning was significantly reduced by UE2316 in a non-reversible manner. When the order of treatment was reversed following extinction of the original fear memory, and a second foot-shock conditioning was given in a novel context, UE2316 treated aged mice (previously on vehicle) now showed increased fear memory compared to vehicle-treated aged mice (previously on UE2316). Renewal of the original extinguished fear memory triggered by exposure to a new environmental context may explain these effects. Thus 11β-HSD1 inhibition reverses spatial memory impairments with ageing while reducing the strength and persistence of new contextual fear memories. Potentially this could help prevent anxiety-related disorders in vulnerable elderly individuals. PMID:25497454
Wheelan, Nicola; Webster, Scott P; Kenyon, Christopher J; Caughey, Sarah; Walker, Brian R; Holmes, Megan C; Seckl, Jonathan R; Yau, Joyce L W
High glucocorticoid levels induced by stress enhance the memory of fearful events and may contribute to the development of anxiety and posttraumatic stress disorder. In contrast, elevated glucocorticoids associated with ageing impair spatial memory. We have previously shown that pharmacological inhibition of the intracellular glucocorticoid-amplifying enzyme 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) improves spatial memory in aged mice. However, it is not known whether inhibition of 11β-HSD1 will have any beneficial effects on contextual fear memories in aged mice. Here, we examined the effects of UE2316, a selective 11β-HSD1 inhibitor which accesses the brain, on both spatial and contextual fear memories in aged mice using a vehicle-controlled crossover study design. Short-term UE2316 treatment improved spatial memory in aged mice, an effect which was reversed when UE2316 was substituted with vehicle. In contrast, contextual fear memory induced by foot-shock conditioning was significantly reduced by UE2316 in a non-reversible manner. When the order of treatment was reversed following extinction of the original fear memory, and a second foot-shock conditioning was given in a novel context, UE2316 treated aged mice (previously on vehicle) now showed increased fear memory compared to vehicle-treated aged mice (previously on UE2316). Renewal of the original extinguished fear memory triggered by exposure to a new environmental context may explain these effects. Thus 11β-HSD1 inhibition reverses spatial memory impairments with ageing while reducing the strength and persistence of new contextual fear memories. Potentially this could help prevent anxiety-related disorders in vulnerable elderly individuals.
Abdel-Salam, Omar M.E.; El-Sayed El-Shamarka, Marwa; Salem, Neveen A.; El-Mosallamy, Aliaa E.M.K.; Sleem, Amany A.
Haloperidol is a classic antipsychotic drug known for its propensity to cause extrapyramidal symptoms and impaired memory, owing to blockade of striatal dopamine D2 receptors. Cinnarizine is a calcium channel blocker with D2 receptor blocking properties which is widely used in treatment of vertiginous disorders. The present study aimed to see whether cinnarizine would worsen the effect of haloperidol on memory function and on oxidative stress in mice brain. Cinnarizine (5, 10 or 20 mg/kg), haloperidol, or haloperidol combined with cinnarizine was administered daily via the subcutaneous route and mice were examined on weekly basis for their ability to locate a submerged plate in the water maze test. Mice were euthanized 30 days after starting drug injection. Malondialdehyde (MDA), reduced glutathione (GSH) and nitric oxide (nitrite/nitrate) were determined in brain. Haloperidol substantially impaired water maze performance. The mean time taken to find the escape platform (latency) was significantly delayed by haloperidol (2 mg/kg, i.p.) on weeks 1-8 of the test, compared with saline control group. In contrast, those treated with haloperidol and cinnarizine showed significantly shorter latencies, which indicated that learning had occurred immediately. Haloperidol resulted in increased MDA in cortex, striatum, cerebellum and midbrain. GSH decreased in cortex, striatum and cerebellum and nitric oxide increased in cortex. Meanwhile, treatment with cinnarizine (20 mg/kg) and haloperidol resulted in significant decrease in MDA cortex, striatum, cerebellum and midbrain and an increase in GSH in cortex and striatum, compared with haloperidol group. These data suggest that cinnarizine improves the haloperidol induced brain oxidative stress and impairment of learning and memory in the water maze test in mice. PMID:27540345
Schroeder, Ulrike; Schroeder, Helmut; Schwegler, Herbert; Sabel, Bernhard A
Phencyclidine (PCP), a non-competitive NMDA-receptor antagonist, is able to induce schizophrenia-like symptoms in animals and in humans. It is known that schizophrenic patients have deficits in memory processes. Therefore, it was investigated whether subchronic pulsatile or continuous application of 5.0 mg kg−1 PCP over 5 days induce short-term memory deficits in holeboard learning and the action of two different neuroleptics on this behavioural test. First, an impairment in the holeboard task was described when the animals were tested 24 h after the last application but not after 15 min or 1 h after the last injection. Secondly, the influence of haloperidol and risperidone on the PCP-induced short-term memory changes was tested. The combined application of PCP and risperidone led to a complete antagonism of the short-term deficits, but the combined treatment with haloperidol was accompanied by a partial abolishment of the PCP-induced deficits. PCP led to an upregulation of the glutamate binding sites in striatum and nucleus accumbens whereas the D2 binding sites were reduced in striatum. The D1 binding sites seem to be unchanged. The receptor protein expression of glutamate receptors mGluR1, GluR2, GluR5/7 and NMDAR1 were not modified in response to PCP treatment. The determination of a subpopulation of GABAergic interneurons shows a decrease of the cells within the CA3 of the hippocampal formation. These findings indicate that PCP induced impairments in short term memory can be detected by holeboard learning and may provide an interesting tool for the search of new neuroleptics. PMID:10780995
Abdel-Salam, Omar M.E.; Salem, Neveen A.; El-Sayed El-Shamarka, Marwa; Al-Said Ahmed, Noha; Seid Hussein, Jihan; El-Khyat, Zakaria A.
Cannabis sativa preparations are the most commonly used illicit drugs worldwide. The present study aimed to investigate the effect of Cannabis sativa extract in the working memory version of the Morris water maze (MWM; Morris, 1984) test and determine the effect of standard memory enhancing drugs. Cannabis sativa was given at doses of 5, 10 or 20 mg/kg (expressed as Δ9-tetrahydrocannabinol) alone or co-administered with donepezil (1 mg/kg), piracetam (150 mg/ kg), vinpocetine (1.5 mg/kg) or ginkgo biloba (25 mg/kg) once daily subcutaneously (s.c.) for one month. Mice were examined three times weekly for their ability to locate a submerged platform. Mice were euthanized 30 days after starting cannabis injection when biochemical assays were carried out. Malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide, glucose and brain monoamines were determined. Cannabis resulted in a significant increase in the time taken to locate the platform and enhanced the memory impairment produced by scopolamine. This effect of cannabis decreased by memory enhancing drugs with piracetam resulting in the most-shorter latency compared with the cannabis. Biochemically, cannabis altered the oxidative status of the brain with decreased MDA, increased GSH, but decreased nitric oxide and glucose. In cannabis-treated rats, the level of GSH in brain was increased after vinpocetine and donepezil and was markedly elevated after Ginkgo biloba. Piracetam restored the decrease in glucose and nitric oxide by cannabis. Cannabis caused dose-dependent increases of brain serotonin, noradrenaline and dopamine. After cannabis treatment, noradrenaline is restored to its normal value by donepezil, vinpocetine or Ginkgo biloba, but increased by piracetam. The level of dopamine was significantly reduced by piracetam, vinpocetine or Ginkgo biloba. These data indicate that cannabis administration is associated with impaired memory performance which is likely to involve decreased brain glucose
Vasek, Michael J; Garber, Charise; Dorsey, Denise; Durrant, Douglas M; Bollman, Bryan; Soung, Allison; Yu, Jinsheng; Perez-Torres, Carlos; Frouin, Arnaud; Wilton, Daniel K; Funk, Kristen; DeMasters, Bette K; Jiang, Xiaoping; Bowen, James R; Mennerick, Steven; Robinson, John K; Garbow, Joel R; Tyler, Kenneth L; Suthar, Mehul S; Schmidt, Robert E; Stevens, Beth; Klein, Robyn S
Over 50% of patients who survive neuroinvasive infection with West Nile virus (WNV) exhibit chronic cognitive sequelae. Although thousands of cases of WNV-mediated memory dysfunction accrue annually, the mechanisms responsible for these impairments are unknown. The classical complement cascade, a key component of innate immune pathogen defence, mediates synaptic pruning by microglia during early postnatal development. Here we show that viral infection of adult hippocampal neurons induces complement-mediated elimination of presynaptic terminals in a murine WNV neuroinvasive disease model. Inoculation of WNV-NS5-E218A, a WNV with a mutant NS5(E218A) protein leads to survival rates and cognitive dysfunction that mirror human WNV neuroinvasive disease. WNV-NS5-E218A-recovered mice (recovery defined as survival after acute infection) display impaired spatial learning and persistence of phagocytic microglia without loss of hippocampal neurons or volume. Hippocampi from WNV-NS5-E218A-recovered mice with poor spatial learning show increased expression of genes that drive synaptic remodelling by microglia via complement. C1QA was upregulated and localized to microglia, infected neurons and presynaptic terminals during WNV neuroinvasive disease. Murine and human WNV neuroinvasive disease post-mortem samples exhibit loss of hippocampal CA3 presynaptic terminals, and murine studies revealed microglial engulfment of presynaptic terminals during acute infection and after recovery. Mice with fewer microglia (Il34(-/-) mice with a deficiency in IL-34 production) or deficiency in complement C3 or C3a receptor were protected from WNV-induced synaptic terminal loss. Our study provides a new murine model of WNV-induced spatial memory impairment, and identifies a potential mechanism underlying neurocognitive impairment in patients recovering from WNV neuroinvasive disease.
Gray, Bradley E; Hahn, Britta; Robinson, Benjamin; Harvey, Alex; Leonard, Carly J; Luck, Steven J; Gold, James M
Recent studies suggest that people with schizophrenia (PSZ) have difficulty distributing their attention broadly. Other research suggests that PSZ have reduced working memory (WM) capacity. This study tested whether these findings reflect a common underlying deficit. We measured the ability to distribute attention by means of the Useful Field of View (UFOV) task, in which participants must distribute attention so that they can discriminate a foveal target and simultaneously localize a peripheral target. Participants included 50 PSZ and 52 healthy control subjects. We found that PSZ exhibited severe impairments in UFOV performance, that UFOV performance was highly correlated with WM capacity in PSZ (r = -.61), and that UFOV impairments could not be explained by either impaired low-level processing or a generalized deficit. These results suggest that a common mechanism explains deficits in the ability to distribute attention broadly, reduced WM capacity, and other aspects of impaired cognition in schizophrenia. We hypothesize that this mechanism may involve abnormal local circuit dynamics that cause a hyperfocusing of resources onto a small number of internal representations.
Lu, Chunming; Qi, Zhenghan; Harris, Adrianne; Weil, Lisa Wisman; Han, Michelle; Halverson, Kelly; Perrachione, Tyler K.; Kjelgaard, Margaret; Wexler, Kenneth; Tager-Flusberg, Helen; Gabrieli, John D. E.
Background Individuals with reading disability or individuals with autism spectrum disorder (ASD) are characterized, respectively, by their difficulties in reading or social communication, but both groups often have impaired phonological working memory (PWM). It is not known whether the impaired PWM reflects distinct or shared neuroanatomical abnormalities in these two diagnostic groups. Methods White-matter structural connectivity via diffusion weighted imaging was examined in sixty-four children, ages 5-17 years, with reading disability, ASD, or typical development (TD), who were matched in age, gender, intelligence, and diffusion data quality. Results Children with reading disability and children with ASD exhibited reduced PWM compared to children with TD. The two diagnostic groups showed altered white-matter microstructure in the temporo-parietal portion of the left arcuate fasciculus (AF) and in the temporo-occipital portion of the right inferior longitudinal fasciculus (ILF), as indexed by reduced fractional anisotropy and increased radial diffusivity. Moreover, the structural integrity of the right ILF was positively correlated with PWM ability in the two diagnostic groups, but not in the TD group. Conclusions These findings suggest that impaired PWM is transdiagnostically associated with shared neuroanatomical abnormalities in ASD and reading disability. Microstructural characteristics in left AF and right ILF may play important roles in the development of PWM. The right ILF may support a compensatory mechanism for children with impaired PWM. PMID:26949750
Palchykova, Svitlana; Winsky-Sommerer, Raphaëlle; Tobler, Irene
There is increasing evidence that sleep facilitates memory acquisition and consolidation. Moreover, the sleep-wake history preceding memory acquisition and retention as well as circadian timing may be important. We showed previously that sleep deprivation (SD) following learning in OF1 mice impaired their performance on an object recognition task. The learning task was scheduled at the end of the 12 h dark period and the test 24 h later. To investigate the influence of the prominent circadian sleep-wake distribution typical for rodents, we now scheduled the learning task at the beginning of the dark period. Wakefulness following immediately after the learning task was attained either by gentle interference (SD; n = 20) or by spontaneous wheel running (RW; n = 20). Two control groups were used: one had no RW throughout the experiment (n = 23), while the other group's wheel was blocked immediately after acquisition (n = 16), thereby preventing its use until testing. Recognition memory, defined as the difference in exploration of a novel and of familiar objects, was assessed 24 h later during the test phase. Motor activity and RW use were continuously recorded. Remarkably, performance on the object recognition task was not influenced by the protocols; the waking period following acquisition did not impair memory, independent of the method inducing wakefulness (i.e., sleep deprivation or spontaneous running). Thus, all groups explored the novel object significantly longer than the familiar ones during the test phase. Interestingly, neither the amount of rest lost during the SD interventions nor the amount of rest preceding acquisition influenced performance. However, the total amount of rest obtained by the control and SD mice subjected to acquisition at "dark offset" correlated positively (r = 0.66) with memory at test, while no such relationship occurred in the corresponding groups tested at dark onset. Neither the amount of running nor intermediate rest correlated
Morris, Ken A.; Gold, Paul E.
Epinephrine enhances memory in young adult rats, in part, by increasing blood glucose levels needed to modulate memory. In old rats, epinephrine is deficient at raising blood glucose levels and thus is only moderately effective at enhancing memory. In contrast, systemic glucose injections improve memory in old rats, with resulting memory performance equal to that of young rats. The diminished response of glucose to training in old rats may blunt downstream neurochemical and molecular mechanisms needed to upregulate memory processes. In the first experiment, young adult and old rats were trained on an inhibitory avoidance task with immediate post-training injections of aCSF or glucose into the dorsal hippocampus. Old rats had significant memory impairments compared to young rats 7 days after training. Intrahippocampal injections of glucose reversed age-related deficits, improving memory scores in old rats to values seen in young rats. A second experiment examined age-related changes in activation of the transcription factor CREB, which is widely implicated in memory formation and may act downstream of hormonal and metabolic signals. Activation was assessed in response to training with systemic injections of epinephrine and glucose at doses known to enhance memory. Young adult and old rats were trained on inhibitory avoidance with immediate post-training systemic injections of saline, epinephrine, or glucose. After training, old rats had significant impairments in CREB phosphorylation in area CA1 and the dentate gyrus region of the hippocampus, and in the basolateral and lateral amygdala. Epinephrine and glucose attenuated age-related deficits in CREB phosphorylation, but were more effective in the amygdala and hippocampus, respectively. Together, these results support the view that age-related changes in blood glucose responses to epinephrine contribute to memory impairments, which may be related to alterations in regional patterns of CREB phosphorylation. PMID
Morris, Ken A; Gold, Paul E
Epinephrine enhances memory in young adult rats, in part, by increasing blood glucose levels needed to modulate memory. In old rats, epinephrine is deficient at raising blood glucose levels and thus is only moderately effective at enhancing memory. In contrast, systemic glucose injections improve memory in old rats, with resulting memory performance equal to that of young rats. The diminished response of glucose to training in old rats may blunt downstream neurochemical and molecular mechanisms needed to upregulate memory processes. In the first experiment, young adult and old rats were trained on an inhibitory avoidance task with immediate post-training injections of aCSF or glucose into the dorsal hippocampus. Old rats had significant memory impairments compared to young rats 7 days after training. Intrahippocampal injections of glucose reversed age-related deficits, improving memory scores in old rats to values seen in young rats. A second experiment examined age-related changes in activation of the transcription factor CREB, which is widely implicated in memory formation and may act downstream of hormonal and metabolic signals. Activation was assessed in response to training with systemic injections of epinephrine and glucose at doses known to enhance memory. Young adult and old rats were trained on inhibitory avoidance with immediate post-training systemic injections of saline, epinephrine, or glucose. After training, old rats had significant impairments in CREB phosphorylation in area CA1 and the dentate gyrus region of the hippocampus, and in the basolateral and lateral amygdala. Epinephrine and glucose attenuated age-related deficits in CREB phosphorylation, but were more effective in the amygdala and hippocampus, respectively. Together, these results support the view that age-related changes in blood glucose responses to epinephrine contribute to memory impairments, which may be related to alterations in regional patterns of CREB phosphorylation.
Sil, Susmita; Ghosh, Tusharkanti; Ghosh, Rupsa; Gupta, Pritha
Intracerebroventricular (i.c.v.) injection of colchicine induces neurodegeneration, memory impairments and changes of some systemic immune responses in rats. Though the role of cox 2 in these colchicine induced changes have been evaluated, the influence of nitric oxide synthase (NOS) remains to be studied. The present study was designed to assess the role of NOS on the i.c.v. colchicine induced neurodegeneration, memory impairments and changes of some systemic immune responses by inhibiting its activity with aminoguanidine. In the present study the impairments of working and reference memories, neurodegeneration (chromatolysis and plaque formation) and changes of neuroinflammatory markers in the hippocampus (increased TNF α, IL 1β, ROS and nitrite) along with changes of serum inflammatory markers (TNF α, IL 1β, ROS and nitrite) and alteration of systemic immune responses (higher phagocytic activity of blood WBC and splenic PMN, higher cytotoxicity and lower leukocyte adhesion inhibition index of splenic MNC) were measured in the intracerebroventricular colchicine injected rats (ICIR). Administration of aminoguanidine (p.o. 30/50mg/kg body weight) to ICIR resulted in recovery of neuroinflammation and partial prevention of neurodegeneration which could be corroborated with the partial recovery of memory impairments in this model. The recovery of serum inflammatory markers and the systemic immune responses in ICIR was also observed after administration of aminoguanidine. Therefore, the present study shows that aminoguanidine can protect the colchicine induced neurodegeneration, memory impairments, and changes of systemic immune systemic responses in ICIR by inhibiting the iNOS.
Inostroza, Marion; Brotons-Mas, Jorge R; Laurent, François; Cid, Elena; de la Prida, Liset Menendez
Episodic memory deficit is a common cognitive disorder in human temporal lobe epilepsy (TLE). However, no animal model of TLE has been shown to specifically replicate this cognitive dysfunction, which has limited its translational appeal. Here, using a task that tests for nonverbal correlates of episodic-like memory in rats, we show that kainate-treated TLE rats exhibit a selective impairment of the "what-where-when" memory while preserving other forms of hippocampal-dependent memories. Assisted by multisite silicon probes, we recorded from the dorsal hippocampus of behaving animals to control for seizure-related factors and to look for electrophysiological signatures of cognitive impairment. Analyses of hippocampal local field potentials showed that both the power of theta rhythm and its coordination across CA1 and the DG-measured as theta coherence and phase locking-were selectively disrupted. This disruption represented a basal condition of the chronic epileptic hippocampus that was linked to different features of memory impairment. Theta power was more correlated with the spatial than with the temporal component of the task, while measures of theta coordination correlated with the temporal component. We conclude that episodic-like memory, as tested in the what-where-when task, is specifically affected in experimental TLE and that the impairment of hippocampal theta activity might be central to this dysfunction.
Das, Sambhunath; Nanda, Sunil K.; Bisoi, Akshya K.; Wadhawan, Ashima N.
Context: Frequent incidence of early postoperative memory impairment (POMI) after cardiac surgery remains a concern because of associated morbidity, impaired quality of life, and increased health care cost. Aim: To assess the effect of preoperative statin therapy on POMI in patients undergoing off-pump coronary artery bypass (OPCAB) surgery. Setting and Design: Prospective observational study in a tertiary level hospital. Methods: Sixty patients aged 45–65 years undergoing OPCAB surgery were allocated into two groups of 30 each. Group A patients were receiving statin and Group B patients were not receiving statins. All patients underwent memory function assessment preoperatively after admission to hospital and on the 6th postoperative day using postgraduate institute memory scale. Statistical Analysis: Appropriate tests were applied with SPSS 20 to compare both groups. The value P < 0.05 was considered statistically significant. Multiple regression analysis was performed with confounding factors to determine the effect on memory impairment. Results: Patients in Group A showed significant postoperative deterioration in 6 of the 10 functions and in Group B showed deterioration in 9 of 10 functions tested compared to preoperative scores. Intergroup comparison detected less POMI in Group A compared to Group B and was statistically significant in 8 memory functions. Multiple regression analysis detected statin as an independent factor in preventing memory impairment. Conclusions: Preoperative statin therapy attenuates the early POMI in patients undergoing OPCAB. Future long-term studies will define the efficacy of statin on POMI. PMID:26750672
Alzoubi, Karem H; Khabour, Omar F; Salah, Heba A; Hasan, Zuheir
Memory and learning are impaired by imbalanced diet consumption. High-fat high-carbohydrate diet (HFCD) induces oxidative stress, which results in neuronal damage and interference with synaptic transmission; hence, a decline in cognitive function. Vitamin E is a fat soluble antioxidant that is believed to have positive effects on learning and memory. In this study, we tested the hypothesis that chronic administration of vitamin E prevents learning and memory impairment induced by HFCD. In addition, possible molecular targets for HFCD, and vitamin E that lead to cognitive effects were examined. Vitamin E and/or HFCD were concurrently administered to animals for 6 weeks. Thereafter, behavioral studies were conducted to test the spatial learning and memory using radial arm water maze (RAWM). Additionally, brain derived neurotrophic factor (BDNF) level and antioxidant markers were assessed in the hippocampus. The results of this project revealed that HFCD impairs both short-term and long-term memories (p<0.05). The administration of vitamin E prevented the memory impairment induced by HFCD consumption (p<0.05). The consumption of HFCD reduced activities of hippocampal superoxide dismutase (SOD) and catalase (p<0.05); whereas the levels of thiobarbituric acid reactive substances (TBARS) and oxidized glutathione (GSSG) were elevated (p<0.05). The administration of vitamin E normalized the effect of HFCD on the oxidative stress markers. None of the treatments induced changes in the levels of BDNF or glutathione peroxidase (GPx). In conclusion, HFCD induces memory impairment, and the administration of vitamin E prevented this impairment probably through normalizing antioxidant mechanisms in the hippocampus.
Lenaert, Bert; Boddez, Yannick; Vervliet, Bram; Schruers, Koen; Hermans, Dirk
Associative learning plays an important role in the development of anxiety disorders, but a thorough understanding of the variables that impact such learning is still lacking. We investigated whether individual differences in autobiographical memory specificity are related to discrimination learning and generalization. In an associative learning task, participants learned the association between two pictures of female faces and a non-aversive outcome. Subsequently, six morphed pictures functioning as generalization stimuli (GSs) were introduced. In a sample of healthy participants (Study 1), we did not find evidence for differences in discrimination learning as a function of memory specificity. In a sample of anxiety disorder patients (Study 2), individuals who were characterized by low memory specificity showed deficient discrimination learning relative to high specific individuals. In contrast to previous findings, results revealed no effect of memory specificity on generalization. These results indicate that impaired discrimination learning, previously shown in patients suffering from an anxiety disorder, may be—in part—due to limited memory specificity. Together, these studies emphasize the importance of incorporating cognitive variables in associative learning theories and their implications for the development of anxiety disorders. In addition, re-analyses of the data (Study 3) showed that patients suffering from panic disorder showed higher outcome expectancies in the presence of the stimulus that was never followed by an outcome during discrimination training, relative to patients suffering from other anxiety disorders and healthy participants. Because we used a neutral, non-aversive outcome (i.e., drawing of a lightning bolt), these data suggest that learning abnormalities in panic disorder may not be restricted to fear learning, but rather reflect a more general associative learning deficit that also manifests in fear irrelevant contexts. PMID
Hwang, Jae Yeon; Kim, Ju Hwan; Yun, Na Young; Oh, Sang Yeon; Song, Ju Kyung; Seo, Hyun Ok; Kim, Yun-Bae; Hwang, Dae Yeon; Oh, Ki-Wan; Han, Sang-Bae; Hong, Jin Tae
Chemokine receptors are implicated in inflammation and immune responses. Neuro-inflammation is associated with activation of astrocyte and amyloid-beta (Aβ) generations that lead to pathogenesis of Alzheimer disease (AD). Previous our study showed that deficiency of CC chemokine receptor 5 (CCR5) results in activation of astrocytes and Aβ deposit, and thus memory dysfunction through increase of CC chemokine receptor 2 (CCR2) expression. CCR5 knockout mice were used as an animal model with memory dysfunction. For the purpose LPS was injected i.p. daily (0.25 mg/kg/day). The memory dysfunctions were much higher in LPS-injected CCR5 knockout mice compared to CCR5 wild type mice as well as non-injected CCR5 knockout mice. Associated with severe memory dysfuction in LPS injected CCR5 knockout mice, LPS injection significant increase expression of inflammatory proteins, astrocyte activation, expressions of β-secretase as well as Aβ deposition in the brain of CCR5 knockout mice as compared with that of CCR5 wild type mice. In CCR5 knockout mice, CCR2 expressions were high and co-localized with GFAP which was significantly elevated by LPS. Expression of monocyte chemoattractant protein-1 (MCP-1) which ligands of CCR2 also increased by LPS injection, and increment of MCP-1 expression is much higher in CCR5 knockout mice. BV-2 cells treated with CCR5 antagonist, D-ala-peptide T-amide (DAPTA) and cultured astrocytes isolated from CCR5 knockout mice treated with LPS (1 μg/ml) and CCR2 antagonist, decreased the NF-ĸB activation and Aβ level. These findings suggest that the deficiency of CCR5 enhances response of LPS, which accelerates to neuro-inflammation and memory impairment. PMID:26910914
Jiang, Zhong-Jiao; Wang, Chun-Yang; Xie, Xun; Yang, Jing-Fang; Huang, Jun-Ni; Cao, Zhi-Ping; Xiao, Peng; Li, Chu-Hua
Background and Purpose Schizandrin (SCH) has been reported to prevent or reduce learning and memory defects. However, it is not known whether SCH ameliorates cognitive impairments induced by oestrogen deficiency. In the present study, we investigated the effect of SCH on memory in ovariectomized (OVX) and non-OVX rats. Experimental Approach A passive avoidance test was used to evaluate the effect of SCH on memory. Field EPSPs were recorded in hippocampal slices using an electrophysiological method. In OVX rats, biochemical parameters in the bilateral hippocampus were measured; these included superoxide dismutase (SOD), malondialdehyde (MDA) and AChE. Also, the number of NADPH-diaphorase (NADPH-d) positive neurons was counted by NADPH-d histochemistry staining technique. Key Results Oral SCH improved the memory and facilitated the induction of long-term potentiation in non-OVX and OVX rats; this effect was more obvious in OVX rats. Similarly, SCH perfusion enhanced synaptic transmission in hippocampal slices from both non-OVX and OVX rats. However, SCH perfusion reduced the ratio of paired-pulse facilitation only in OVX but not in non-OVX rats. In addition, SCH decreased AChE activity and MDA level and increased SOD activity and the number of NADPH-d-positive neurons in OVX rats. Conclusions and Implications SCH improves memory in OVX rats and its potential mechanisms may include a reduction in the loss of hippocampal NADPH-d positive neurons, an increase of antioxidant properties and a potentiation of synaptic transmission that possibly involves to enhance cholinergic function. Overall, our findings indicate that SCH has potential as a therapeutic strategy for the cognitive dysfunctions associated with the menopause. PMID:25573619
Vazdarjanova, A; Bunting, K; Muthusamy, N; Bergson, C
Calcyon regulates activity-dependent internalization of α-amino-3-hydroxyl-5-methyl-4-isoxazole-propionate (AMPA) glutamate receptors and long-term depression of excitatory synapses. Elevated levels of calcyon are consistently observed in brains from schizophrenic patients, and the calcyon gene is associated with attention-deficit hyperactivity disorder. Executive function deficits are common to both disorders, and at least for schizophrenia, the etiology appears to involve both heritable and neurodevelopmental factors. Here, we show with calcyon-overexpressing Cal(OE) transgenic mice that lifelong calcyon upregulation impairs executive functions including response inhibition and working memory, without producing learning and memory deficits in general. As response inhibition and working memory, as well as the underlying neural circuitry, continue to mature into early adulthood, we functionally silenced the transgene during postnatal days 28-49, a period corresponding to adolescence. Remarkably, the response inhibition and working memory deficits including perseverative behavior were absent in adult Cal(OE) mice with the transgene silenced in adolescence. Suppressing the calcyon transgene in adulthood only partially rescued the deficits, suggesting calcyon upregulation in adolescence irreversibly alters development of neural circuits supporting mature response inhibition and working memory. Brain regional immunoblots revealed a prominent downregulation of AMPA GluR1 subunits in hippocampus and GluR2/3 subunits in hippocampus and prefrontal cortex of the Cal(OE) mice. Silencing the transgene in adolescence prevented the decrease in hippocampal GluR1, further implicating altered fronto-hippocampal connectivity in the executive function deficits observed in the Cal(OE) mice. Treatments that mitigate the effects of high levels of calcyon during adolescence could preempt adult deficits in executive functions in individuals at risk for serious mental illness.
Hwang, Chul Ju; Park, Mi Hee; Hwang, Jae Yeon; Kim, Ju Hwan; Yun, Na Young; Oh, Sang Yeon; Song, Ju Kyung; Seo, Hyun Ok; Kim, Yun-Bae; Hwang, Dae Yeon; Oh, Ki-Wan; Han, Sang-Bae; Hong, Jin Tae
Chemokine receptors are implicated in inflammation and immune responses. Neuro-inflammation is associated with activation of astrocyte and amyloid-beta (Aβ) generations that lead to pathogenesis of Alzheimer disease (AD). Previous our study showed that deficiency of CC chemokine receptor 5 (CCR5) results in activation of astrocytes and Aβ deposit, and thus memory dysfunction through increase of CC chemokine receptor 2 (CCR2) expression. CCR5 knockout mice were used as an animal model with memory dysfunction. For the purpose LPS was injected i.p. daily (0.25 mg/kg/day). The memory dysfunctions were much higher in LPS-injected CCR5 knockout mice compared to CCR5 wild type mice as well as non-injected CCR5 knockout mice. Associated with severe memory dysfuction in LPS injected CCR5 knockout mice, LPS injection significant increase expression of inflammatory proteins, astrocyte activation, expressions of β-secretase as well as Aβ deposition in the brain of CCR5 knockout mice as compared with that of CCR5 wild type mice. In CCR5 knockout mice, CCR2 expressions were high and co-localized with GFAP which was significantly elevated by LPS. Expression of monocyte chemoattractant protein-1 (MCP-1) which ligands of CCR2 also increased by LPS injection, and increment of MCP-1 expression is much higher in CCR5 knockout mice. BV-2 cells treated with CCR5 antagonist, D-ala-peptide T-amide (DAPTA) and cultured astrocytes isolated from CCR5 knockout mice treated with LPS (1 μg/ml) and CCR2 antagonist, decreased the NF-Ä¸B activation and Aβ level. These findings suggest that the deficiency of CCR5 enhances response of LPS, which accelerates to neuro-inflammation and memory impairment.
Vazdarjanova, Almira; Bunting, Kristopher; Muthusamy, Nagendran; Bergson, Clare
Calcyon regulates activity dependent internalization of AMPA glutamate receptors and long term depression of excitatory synapses. Elevated levels of calcyon are consistently observed in brains from schizophrenic patients, and the calcyon gene is associated with attention deficit hyperactivity disorder. Executive function deficits are common to both disorders, and at least for schizophrenia, the etiology appears to involve both heritable and neurodevelopmental factors. Here, we show with calcyon overexpressing CalOE transgenic mice that lifelong calcyon upregulation impairs executive functions including response inhibition and working memory, without producing learning and memory deficits in general. As response inhibition and working memory, as well as the underlying neural circuitry continue to mature into early adulthood, we functionally silenced the transgene during postnatal days 28–49, a period corresponding to adolescence. Remarkably, the response inhibition and working memory deficits including perseverative behavior were absent in adult CalOE mice with the transgene silenced in adolescence. Suppressing the calcyon transgene in adulthood only partially rescued the deficits, suggesting calcyon upregulation in adolescence irreversibly alters development of neural circuits supporting mature response inhibition and working memory. Brain regional immunoblots revealed a prominent down-regulation of AMPA GluR1 subunits in hippocampus, and GluR2/3 subunits in hippocampus and prefrontal cortex of the CalOE mice. Silencing the transgene in adolescence prevented the decrease in hippocampal GluR1, further implicating altered frontohippocampal connectivity in the executive function deficits observed in the CalOE mice. Treatments that mitigate the effects of high levels of calcyon during adolescence could preempt adult deficits in executive functions in individuals at-risk for serious mental illness. PMID:21403673
Racinais, S; Gaoua, N; Grantham, J
The aims of this study were to determine (i) the effect of passive hyperthermia on motor drive and cognitive function, and (ii) whether head cooling can limit the hyperthermia-induced alterations. Sixteen subjects were randomly exposed for 2 h to three different conditions: control (Con, 20 degrees C), hot (Hot, 50 degrees C) and hot head cool (HHC--where cold packs were applied to the head under Hot conditions). Three cognitive tests measuring attention and two measuring memory were performed. Neuromuscular testing included electrically evoked muscle action potentials (M-waves) and reflex waves (H-reflex) at rest and during brief (4-5 s) and sustained (120 s) maximal voluntary contractions (MVC) of the plantar flexors. All the tests were performed in the environmental room. During brief MVC, torque was significantly lower in both Hot and HHC as compared to Con (P < 0.05). The decrease in muscle activation was significant in Hot (P < 0.05) but not in HBC (P = 0.07). This was accompanied by peripheral failures in the transmission of the neural drive at both spinal (significant decrements in H-reflexes and V-waves, P < 0.05) and neuromuscular junction (significant decrements in M-waves, P < 0.05) levels. During sustained MVC, muscle activation was further depressed (P < 0.05) without any concomitant failures in M-waves, suggesting neural activation adjustments occurring probably at the supraspinal level. Cerebral perturbations were confirmed by significant decrements in both memory tests in Hot as compared with Con (P < 0.05) but not in simple tests (attention tests) that were not affected by hyperthermia. The decrement in memory capacity suggested the existence of frontal lobe activity impairments. Thus, HHC preserved memory capacity but not the visual memory.
Lenaert, Bert; Boddez, Yannick; Vervliet, Bram; Schruers, Koen; Hermans, Dirk
Associative learning plays an important role in the development of anxiety disorders, but a thorough understanding of the variables that impact such learning is still lacking. We investigated whether individual differences in autobiographical memory specificity are related to discrimination learning and generalization. In an associative learning task, participants learned the association between two pictures of female faces and a non-aversive outcome. Subsequently, six morphed pictures functioning as generalization stimuli (GSs) were introduced. In a sample of healthy participants (Study 1), we did not find evidence for differences in discrimination learning as a function of memory specificity. In a sample of anxiety disorder patients (Study 2), individuals who were characterized by low memory specificity showed deficient discrimination learning relative to high specific individuals. In contrast to previous findings, results revealed no effect of memory specificity on generalization. These results indicate that impaired discrimination learning, previously shown in patients suffering from an anxiety disorder, may be-in part-due to limited memory specificity. Together, these studies emphasize the importance of incorporating cognitive variables in associative learning theories and their implications for the development of anxiety disorders. In addition, re-analyses of the data (Study 3) showed that patients suffering from panic disorder showed higher outcome expectancies in the presence of the stimulus that was never followed by an outcome during discrimination training, relative to patients suffering from other anxiety disorders and healthy participants. Because we used a neutral, non-aversive outcome (i.e., drawing of a lightning bolt), these data suggest that learning abnormalities in panic disorder may not be restricted to fear learning, but rather reflect a more general associative learning deficit that also manifests in fear irrelevant contexts.
Mika, Agnieszka; Mazur, Gabriel J; Hoffman, Ann N; Talboom, Joshua S; Bimonte-Nelson, Heather A; Sanabria, Federico; Conrad, Cheryl D
Chronic stress leads to neurochemical and structural alterations in the prefrontal cortex (PFC) that correspond to deficits in PFC-mediated behaviors. The present study examined the effects of chronic restraint stress on response inhibition (using a response-withholding task, the fixed-minimum interval schedule of reinforcement, or FMI), and working memory (using a radial arm water maze, RAWM). Adult male Sprague-Dawley rats were first trained on the RAWM and subsequently trained on FMI. After acquisition of FMI, rats were assigned to a restraint stress (6h/d/28d in wire mesh restrainers) or control condition. Immediately after chronic stress, rats were tested on FMI and subsequently on RAWM. FMI results suggest that chronic stress reduces response inhibition capacity and motivation to initiate the task on selective conditions when sucrose reward was not obtained on the preceding trial. RAWM results suggest that chronic stress produces transient deficits in working memory without altering previously consolidated reference memory. Behavioral measures from FMI failed to correlate with metrics from RAWM except for one in which changes in FMI timing imprecision negatively correlated with changes in RAWM working memory errors for the controls, a finding that was not observed following chronic stress. Fisher's r-to-z transformation revealed no significant differences between control and stress groups with correlation coefficients. These findings are the first to show that chronic stress impairs both response inhibition and working memory, two behaviors that have never been directly compared within the same animals after chronic stress, using FMI, an appetitive task, and RAWM, a nonappetitive task.
Kawaguchi, Shinichiro; Kuwahara, Rika; Kohara, Yumi; Uchida, Yutaro; Oku, Yushi; Yamashita, Kimihiro
Nonylphenol ethoxylate (NPE) is a non-ionic surfactant, that is degraded to short-chain NPE and 4-nonylphenol (NP) by bacteria in the environment. NP, one of the most common environmental endocrine disruptors, exhibits weak estrogen-like activity. In this study, we investigated whether oral administration of NP (at 0.5 and 5 mg/kg doses) affects spatial learning and memory, general activity, emotionality, and fear-motivated learning and memory in male and female Sprague-Dawley (SD) rats. SD rats of both sexes were evaluated using a battery of behavioral tests, including an appetite-motivated maze test (MAZE test) that was used to assess spatial learning and memory. In the MAZE test, the time required to reach the reward in male rats treated with 0.5 mg/kg NP group and female rats administered 5 mg/kg NP was significantly longer than that for control animals of the corresponding sex. In other behavioral tests, no significant differences were observed between the control group and either of the NP-treated groups of male rats. In female rats, inner and ambulation values for animals administered 0.5 mg/kg NP were significantly higher than those measured in control animals in open-field test, while the latency in the group treated with 5 mg/kg NP was significantly shorter compared to the control group in step-through passive avoidance test. This study indicates that oral administration of a low-dose of NP slightly impairs spatial learning and memory performance in male and female rats, and alters emotionality and fear-motivated learning and memory in female rats only.
Majkutewicz, Irena; Kurowska, Ewelina; Podlacha, Magdalena; Myślińska, Dorota; Grembecka, Beata; Ruciński, Jan; Plucińska, Karolina; Jerzemowska, Grażyna; Wrona, Danuta
Intracerebroventricular (ICV) injection of streptozotocin (STZ) is a widely-accepted animal model of sporadic Alzheimer's disease (sAD). The present study evaluated the ability of dimethyl fumarate (DMF), an agent with antioxidant and anti-inflammatory properties, to prevent spatial memory impairments and hippocampal neurodegeneration mediated by ICV injection of STZ in 4-month-old rats. Rodent chow containing DMF (0.4%) or standard rodent chow was made available on day 0. Rat body weight and food intake were measured daily for whole the experiment (21days). STZ or vehicle (SHAM) ICV injections were performed on days 2 and 4. Spatial reference and working memory were evaluated using the Morris water maze on days 14-21. Cells containing Fluoro-Jade B (neurodegeneration marker), IL-6, IL-10 were quantified in the hippocampus and choline acetyltransferase (ChAT) in the basal forebrain. The disruption of spatial memory and a high density of hippocampal CA1-3 cells labeled with Fluoro-Jade B or containing IL-6 or IL-10 were observed in the STZ group but not in the STZ+DMF group, as compared to the SHAM or SHAM+DMF groups. STZ vs. STZ+DMF differences were found: worse reference memory acquisition, fewer ChAT-positive neurons in the medial septum (Ch1), more Fluoro-Jade-positive CA1 hippocampal cells in STZ rats. DMF therapy in a rodent model of sAD prevented the disruption of spatial reference and working memory, loss of Ch1 cholinergic cells and hippocampal neurodegeneration as well as the induction of IL-6 and IL-10 in CA1. These beneficial cognitive and molecular effects validate the anti-inflammatory and neuroprotective properties of DMF in the hippocampus.
Navarrete-Opazo, Angela; Alcayaga, Julio; Testa, Denisse; Quinteros, Ana Luisa
There is a critical need for new therapeutic strategies to restore motor function in patients with spinal cord injuries (SCIs), without unwanted effects. Intermittent hypoxia (IH) induces plasticity in spared synaptic pathways to motor neurons below the level of injury, which can be harnessed to elicit motor recovery in incomplete SCI patients. However, there is conflicting evidence regarding the effects of IH on memory function. The aim of this study was to assess episodic verbal and visual memory function with the Complutense verbal learning test (TAVEC) and the Rey-Osterrieth Complex Figure Test (ROCF), respectively, before and after a 4-week protocol of repetitive IH combined with body weight-supported treadmill training (BWSTT) in incomplete ASIA C and D SCI subjects. Subjects received either IH (cycling 9%/21% FiO2 every 1.5 min, 15 cycles per day) or continued normoxia (Nx, 21% FiO2) combined with 45 min of BWSTT for 5 consecutive days, followed by 3 times per week IH and BWSTT for 3 additional weeks. ROCF Z scores between IH plus BWSTT and Nx plus BWSTT were not significantly different (p = .43). Compared with baseline, IH and BWSTT group showed a significantly greater (p < .05) verbal memory performance for immediate, short-term, and long-term recall; however, it was not different from Nx plus BWSTT group in all verbal memory components (p > .05). Our results suggest that a 4-week protocol of moderate IH does not elicit visual or verbal memory impairment. Thus, repetitive IH may be a safe therapeutic approach to incomplete spinal cord injury patients, without deleterious cognitive effects.
Smith, J Carson; Nielson, Kristy A; Antuono, Piero; Lyons, Jeri-Annette; Hanson, Ryan J; Butts, Alissa M; Hantke, Nathan C; Verber, Matthew D
Mild cognitive impairment (MCI) is associated with early memory loss, Alzheimer's disease (AD) neuropathology, inefficient or ineffective neural processing, and increased risk for AD. Unfortunately, treatments aimed at improving clinical symptoms or markers of brain function generally have been of limited value. Physical exercise is often recommended for people diagnosed with MCI, primarily because of its widely reported cognitive benefits in healthy older adults. However, it is unknown if exercise actually benefits brain function during memory retrieval in MCI. Here, we examined the effects of exercise training on semantic memory activation during functional magnetic resonance imaging (fMRI). Seventeen MCI participants and 18 cognitively intact controls, similar in sex, age, education, genetic risk, and medication use, volunteered for a 12-week exercise intervention consisting of supervised treadmill walking at a moderate intensity. Both MCI and control participants significantly increased their cardiorespiratory fitness by approximately 10% on a treadmill exercise test. Before and after the exercise intervention, participants completed an fMRI famous name discrimination task and a neuropsychological battery, Performance on Trial 1 of a list-learning task significantly improved in the MCI participants. Eleven brain regions activated during the semantic memory task showed a significant decrease in activation intensity following the intervention that was similar between groups (p-values ranged 0.048 to 0.0001). These findings suggest exercise may improve neural efficiency during semantic memory retrieval in MCI and cognitively intact older adults, and may lead to improvement in cognitive function. Clinical trials are needed to determine if exercise is effective to delay conversion to AD.
Smith, J. Carson; Nielson, Kristy A.; Antuono, Piero; Lyons, Jeri-Annette; Hanson, Ryan J.; Butts, Alissa M.; Hantke, Nathan C.; Verber, Matthew D.
Mild cognitive impairment (MCI) is associated with early memory loss, Alzheimer neuropathology, inefficient or ineffective neural processing, and increased risk for Alzheimer’s disease (AD). Unfortunately, treatments aimed at improving clinical symptoms or markers of brain function generally have been of limited value. Physical exercise is often recommended for people diagnosed with MCI, primarily because of its widely reported cognitive benefits in healthy older adults. However, it is unknown if exercise actually benefits brain function during memory retrieval in MCI. Here, we examined the effects of exercise training on semantic memory activation during functional magnetic resonance imaging. Seventeen MCI participants and 18 cognitively intact controls, similar in sex, age, education, genetic risk, and medication use, volunteered for a 12-week exercise intervention consisting of supervised treadmill walking at a moderate intensity. Both MCI and control participants significantly increased their cardiorespiratory fitness by approximately 10% on a treadmill exercise test. Before and after the exercise intervention, participants completed a fMRI famous name discrimination task and a neuropsychological battery, Performance on Trial 1 of a list-learning task significantly improved in the MCI participants. Eleven brain regions activated during the semantic memory task showed a significant decrease in activation intensity following the intervention that was similar between groups (p-values ranged .048 to .0001). These findings suggest exercise may improve neural efficiency during semantic memory retrieval in MCI and cognitively intact older adults, and may lead to improvement in cognitive function. Clinical trials are needed to determine if exercise is effective to delay conversion to AD. PMID:23803298
Tota, Santoshkumar; Kamat, Pradeep Kumar; Shukla, Rakesh; Nath, Chandishwar
Recently, silibinin, a clinically used hepatoprotectant, has been reported to prevent amyloid beta induced memory impairment by reducing oxidative stress and inflammation in mice brain. However, the exact mechanism of neuroprotective effect of silibinin has not been properly studied especially in context of brain energy metabolism and cholinergic functions, the essential factors that undergo impairment in Alzheimer's disease. Therefore, the present study investigated the effect of silibinin on impairment in memory, brain energy metabolism and cholinergic function following intracerebral (IC) streptozotocin (STZ) administration in mice. STZ (0.5mg/kg), administered twice at an interval of 48h, caused significant memory impairment tested by Morris water maze. Further, STZ significantly decreased ATP and increased synaptosomal calcium level in mice brain. Increased oxidative and nitrosative stress was also observed in IC STZ injected mice brain. STZ IC induced memory impairment is associated with increased activity and mRNA expression of acetylcholinesterase (AChE) and decreased α-7 nicotinic acetylcholine receptor (α-7-nAChR) mRNA expression in mice brain. Pretreatment with silibinin (100 and 200mg/kg, po) attenuated STZ induced memory impairment by reducing oxidative and nitrosative stress and synaptosomal calcium ion level. Further, silibinin dose dependently restored ATP level indicating improvement in brain energy metabolism. The activity and mRNA expression of AChE was restored by silibinin. Moreover, α-7-nAChR mRNA expression was significantly increased by silibinin in STZ treated mice brain. The present study clearly demonstrates that beneficial effects of silibinin in STZ induced memory impairment in mice is due to improvement in brain energy metabolism and cholinergic function.
Lecourtier, L; Antal, M-C; Cosquer, B; Schumacher, A; Samama, B; Angst, M-J; Ferrandon, A; Koning, E; Cassel, J-C; Nehlig, A
Neonatal ventral hippocampal lesions (NVHL) in rats are considered a potent developmental model of schizophrenia. After NVHL, rats appear normal during their preadolescent time, whereas in early adulthood, they develop behavioral deficits paralleling symptomatic aspects of schizophrenia, including hyperactivity, hypersensitivity to amphetamine (AMPH), prepulse and latent inhibition deficits, reduced social interactions, and spatial working and reference memory alterations. Surprisingly, the question of the consequences of NVHL on postnatal neurobehavioral development has not been addressed. This is of particular importance, as a defective neurobehavioral development could contribute to impairments seen in adult rats. Therefore, at several time points of the early postsurgical life of NVHL rats, we assessed behaviors accounting for neurobehavioral development, including negative geotaxis and grip strength (PD11), locomotor coordination (PD21), and open-field (PD25). At adulthood, the rats were tested for anxiety levels, locomotor activity, as well as spatial reference memory performance. Using a novel task, we also investigated the consequences of the lesions on procedural-like memory, which had never been tested following NVHL. Our results point to preserved neurobehavioral development. They also confirm the already documented locomotor hyperactivity, spatial reference memory impairment, and hyperresponsiveness to AMPH. Finally, our rseults show for the first time that NVHL disabled the development of behavioral routines, suggesting dramatic procedural memory deficits. The presence of procedural memory deficits in adult rats subjected to NHVL suggests that the lesions lead to a wider range of cognitive deficits than previously shown. Interestingly, procedural or implicit memory impairments have also been reported in schizophrenic patients.
Rosa, Nicole M.; Deason, Rebecca G.; Budson, Andrew E.; Gutchess, Angela H.
OBJECTIVE The present study explored the role of self-referencing on false alarm rates among people with mild cognitive impairment suggestive of the early signs of the Alzheimer’s disease pathophysiologic process (MCI-AD). Given that people with MCI-AD demonstrate higher rates of false alarms and that false alarms have been shown to increase for self-relevant information, it was predicted that people with MCI-AD would experience a disproportionate increase in memory errors for highly self-related information. METHODS Twenty-three MCI-ADs with a diagnosis of MCI-AD and 27 healthy controls rated words for self-descriptiveness or commonness and completed a surprise recognition test. RESULTS Contrary to expectations, results indicated that people with MCI-AD were at no greater risk for false alarms than controls as a function of self-descriptiveness, relative to a control condition. Despite the MCI-ADs’ greater bias to say ‘yes’ in the self condition, increasing self-descriptiveness did not lead to higher false alarm rates and did not impair performance in the self condition relative to commonness judgments. CONCLUSIONS Therefore, while people with MCI-AD may be more susceptible to memory errors, they are at no greater risk of self-related errors than healthy controls. PMID:25689510
López-Arnau, Raúl; Martínez-Clemente, José; Pubill, David; Escubedo, Elena; Camarasa, Jorge
Methylone is a cathinone derivative that has recently emerged as a designer drug of abuse in Europe and the USA. Studies on the acute and long-term neurotoxicity of cathinones are starting to be conducted. We investigated the neurochemical/enzymatic changes indicative of neurotoxicity after methylone administration (4 × 20 mg/kg, subcutaneously, per day with 3 h intervals) to adolescent rats, to model human recreational use. In addition, we studied the effect of methylone on spatial learning ad memory using the Morris water maze paradigm. Our experiments were carried out at a high ambient temperature to simulate the hot conditions found in dance clubs where the drug is consumed. We observed a hyperthermic response to methylone that reached a peak 30 min after each dose. We determined a serotonergic impairment in methylone-treated rats, especially in the frontal cortex, where it was accompanied by astrogliosis. Some serotonergic alterations were also present in the hippocampus and striatum. No significant neurotoxic effect on the dopaminergic system was identified. Methylone-treated animals only displayed impairments in the probe trial of the Morris water maze, which concerns reference memory, while the spatial learning process seemed to be preserved.
Lee, Sang-Hak; Ko, Il-Gyu; Kim, Sung-Eun; Hwang, Lakkyong; Jin, Jun-Jang; Choi, Hyun-Hee; Kim, Chang-Ju
Cerebral ischemia is caused by reduced cerebral blood flow due to a transient or permanent cerebral artery occlusion. Ischemic injury in the brain leads to neuronal cell death, and eventually causes neurological impairments. Cordyceps, the name given to the fungi on insects, has abundant useful natural products with various biological activities. Cordyceps is known to have nephroprotective, hepatoprotective, anti-inflammatory, antioxidative, and antiapoptotic effects. We investigated the effects of Cordyceps on short-term memory, neuronal apoptosis, and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils. For this study, a step-down avoidance test, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunohistochemistry for caspase-3 and 5-bromo-2′-de-oxyuridine, and western blot for Bax, Bcl-2, brain-derived neurotrophic factor (BDNF), and tyrosin kinase B were performed. In the present study, Cordyceps alleviated cerebral ischemia-induced short-term memory impairment. Cordyceps showed therapeutic effects through inhibiting cerebral ischemia-induced apoptosis in the hippocampus. Cordyceps suppressed cerebral ischemia-induced cell proliferation in the hippocampal dentate gyrus due to the reduced apoptotic neuronal cell death. Cordyceps treatment also enhanced BDNF and TrkB expressions in the hippocampus of ischemic gerbils. It can be suggested that Cordyceps overcomes cerebral ischemia-induced neuronal apoptosis, thus facilitates recovery following cerebral ischemia injury. PMID:27162767
Lee, Sang-Hak; Ko, Il-Gyu; Kim, Sung-Eun; Hwang, Lakkyong; Jin, Jun-Jang; Choi, Hyun-Hee; Kim, Chang-Ju
Cerebral ischemia is caused by reduced cerebral blood flow due to a transient or permanent cerebral artery occlusion. Ischemic injury in the brain leads to neuronal cell death, and eventually causes neurological impairments. Cordyceps, the name given to the fungi on insects, has abundant useful natural products with various biological activities. Cordyceps is known to have nephroprotective, hepatoprotective, anti-inflammatory, antioxidative, and antiapoptotic effects. We investigated the effects of Cordyceps on short-term memory, neuronal apoptosis, and cell proliferation in the hippocampal dentate gyrus following transient global ischemia in gerbils. For this study, a step-down avoidance test, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay, immunohistochemistry for caspase-3 and 5-bromo-2'-de-oxyuridine, and western blot for Bax, Bcl-2, brain-derived neurotrophic factor (BDNF), and tyrosin kinase B were performed. In the present study, Cordyceps alleviated cerebral ischemia-induced short-term memory impairment. Cordyceps showed therapeutic effects through inhibiting cerebral ischemia-induced apoptosis in the hippocampus. Cordyceps suppressed cerebral ischemia-induced cell proliferation in the hippocampal dentate gyrus due to the reduced apoptotic neuronal cell death. Cordyceps treatment also enhanced BDNF and TrkB expressions in the hippocampus of ischemic gerbils. It can be suggested that Cordyceps overcomes cerebral ischemia-induced neuronal apoptosis, thus facilitates recovery following cerebral ischemia injury.
Naghibi, Sayede Maryam; Hosseini, Mahmoud; Khani, Fatemeh; Rahimi, Motahare; Vafaee, Farzaneh; Rakhshandeh, Hassan; Aghaie, Azita
In the present study, the effect of aqueous extracts of saffron on morphine-induced memory impairment was investigated. On the training trial, the mice received an electric shock when the animals were entered into the dark compartment. Twenty-four and forty-eight hours later, the time latency for entering the dark compartment was recorded and defined as the retention trial. The mice were divided into (1) control, (2) morphine which received morphine before the training in the passive avoidance test, (3–5) three groups treated by 50, 150 and 450 mg/kg of saffron extract before the training trial, and (6 and 7) the two other groups received 150 and 450 mg/kg of saffron extract before the retention trial. The time latency in morphine-treated group was lower than control (P < 0.01). Treatment of the animals by 150 and 450 mg/kg of saffron extract before the training trial increased the time latency at 24 and 48 hours after the training trial (P < 0.05 and P < 0.01). Administration of both 150 and 450 mg/kg doses of the extract before retention trials also increased the time latency (P < 0.01). The results revealed that the saffron extract attenuated morphine-induced memory impairment. PMID:23091484
Naghibi, Sayede Maryam; Hosseini, Mahmoud; Khani, Fatemeh; Rahimi, Motahare; Vafaee, Farzaneh; Rakhshandeh, Hassan; Aghaie, Azita
In the present study, the effect of aqueous extracts of saffron on morphine-induced memory impairment was investigated. On the training trial, the mice received an electric shock when the animals were entered into the dark compartment. Twenty-four and forty-eight hours later, the time latency for entering the dark compartment was recorded and defined as the retention trial. The mice were divided into (1) control, (2) morphine which received morphine before the training in the passive avoidance test, (3-5) three groups treated by 50, 150 and 450 mg/kg of saffron extract before the training trial, and (6 and 7) the two other groups received 150 and 450 mg/kg of saffron extract before the retention trial. The time latency in morphine-treated group was lower than control (P < 0.01). Treatment of the animals by 150 and 450 mg/kg of saffron extract before the training trial increased the time latency at 24 and 48 hours after the training trial (P < 0.05 and P < 0.01). Administration of both 150 and 450 mg/kg doses of the extract before retention trials also increased the time latency (P < 0.01). The results revealed that the saffron extract attenuated morphine-induced memory impairment.
Zou, Rong-Xin; Xu, Yi; Du, Yang; Wang, Shuang; Xu, Lai; Chen, Yuan-Zhi; Wang, Hui-Li; Chen, Xiang-Tao
Chronic lead (Pb) exposure causes cognitive deficits. This study aimed to explore the neuroprotective effect and mechanism of β-asarone, an active component from Chinese Herbs Acorus tatarinowii Schott, to alleviate impairments of spatial memory and synaptogenesis in Pb-exposed rats. Both Sprague-Dawley developmental rat pups and adult rats were used in the study. Developmental rat pups were exposed to Pb throughout the lactation period and β-asarone (10, 40mg kg-1, respectively) was given intraperitoneally from postnatal day 14 to 21. Also, the adult rats were exposed to Pb from embryo stage to 11 weeks old and β-asarone (2.5, 10, 40mg kg-1, respectively) was given from 9 to 11 weeks old. The level of β-asarone in brain tissue was measured by High Performance Liquid Chromatography. The Morris water maze test and Golgi-Cox staining method were used to assess spatial memory ability and synaptogenesis. The protein expression of NR2B subunit of NMDA receptor, Activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) and Wnt family member 7A (Wnt7a) in hippocampus, as well as mRNA expression of Arc/Arg3.1 and Wnt7a, was also explored. We found that β-asarone could pass through the blood brain barrier quickly. And β-asarone effectively attenuated Pb-induced reduction of spine density in hippocampal CA1 and dentate gyrus areas in a dose-dependent manner both in developmental and adult rats, meanwhile the Pb-induced impairments of learning and memory were partially rescued. In addition, β-asarone effectively up-regulated the protein expression of NR2B, Arc and Wnt7a, as well as the mRNA levels of Arc/Arg3.1 and Wnt7a, which had been suppressed by Pb exposure. The results suggest the neuroprotective properties of β-asarone against Pb-induced memory impairments, and the effect is possibly through the regulation of synaptogenesis, which is mediated via Arc/Arg3.1 and Wnt pathway. PMID:27936013
Beheshti, Farimah; Karimi, Sareh; Vafaee, Farzaneh; Shafei, Mohammad Naser; Sadeghnia, Hamid Reza; Hadjzadeh, Mosa Al Reza; Hosseini, Mahmoud
In this study the effects of Vitamin C (Vit C) on hypothyroidism-associated learning and memory impairment in juvenile rats was investigated. The pregnant rats were kept in separate cages. After delivery, they were randomly divided into six groups and treated: (1) Control; (2) Propylthiouracil (PTU) which 0.005% PTU in their drinking; (3-5) Propylthiouracil- Vit C groups; besides PTU, dams in these groups received 10, 100 and 500 mg/kg Vit C respectively, (6) one group as a positive control; the intact rats received an effective dose, 100 mg/kg Vit. C. After delivery, the pups were continued to receive the experimental treatments in their drinking water up to 56th day of their life. Ten male offspring of each group were randomly selected and tested in the Morris water maze (MWM) and passive avoidance (PA) which were started at 63th day (one week after stopping of the treatments). Brains were then removed for biochemical measurements. PTU increased time latency and traveled distance during 5 days in MWM while, reduced the spent time in target quadrant in MWM and step-trough latency (STL) in PA. PTU decreased thiol content, superoxide dismutase (SOD) and catalase (CAT) activities in the brain while, increased molondialdehyde (MDA). In MWM test, 10, 100 and 500 mg/kg Vit C reduced time latency and traveled distance without affecting the traveling speed during 5 days. All doses of Vit C increased the spent time in target quadrant in probe trail of MWM and also increased STL in PA test. Vit C increased thiol, SOD and CAT in the brain tissues while, reduced MDA. Results of present study confirmed the beneficial effects of Vit C on learning and memory. It also demonstrated that Vit C has protective effects on hypothyroidism-associated learning and memory impairment in juvenile rats which might be elucidated by the antioxidative effects.
Abada, Yah-Se K; Nguyen, Huu Phuc; Ellenbroek, Bart; Schreiber, Rudy
Chorea and psychiatric symptoms are hallmarks of Huntington disease (HD), a neurodegenerative disorder, genetically characterized by the presence of expanded CAG repeats (>35) in the Huntingtin (HTT) gene. HD patients present psychiatric symptoms prior to the onset of motor symptoms and we recently found a similar emergence of non motor and motor deficits in BACHD rats carrying the human full length mutated HTT (97 CAG-CAA repeats). We evaluated cognitive performance in reversal learning and associative memory tests in different age cohorts of BACHD rats. Male wild type (WT) and transgenic (TG) rats between 2 and 12 months of age were tested. Learning and strategy shifting were assessed in a cross-maze test. Associative memory was evaluated in different fear conditioning paradigms (context, delay and trace). The possible confound of a fear conditioning phenotype by altered sensitivity to a 'painful' stimulus was assessed in a flinch-jump test. In the cross maze, 6 months old TG rats showed a mild impairment in reversal learning. In the fear conditioning tasks, 4, 6 and 12 months old TG rats showed a marked reduction in contextual fear conditioning. In addition, TG rats showed impaired delay conditioning (9 months) and trace fear conditioning (3 months). This phenotype was unlikely to be affected by a change in 'pain' sensitivity as WT and TG rats showed no difference in their threshold response in the flinch-jump test. Our results suggest that BACHD rats have a profound associative memory deficit and, possibly, a deficit in reversal learning as assessed in a cross maze task. The time course for the emergence of these symptoms (i.e., before the occurrence of motor symptoms) in this rat model for HD appears similar to the time course in patients. These data suggest that BACHD rats may be a useful model for preclinical drug discovery.
Abada, Yah-se K.; Nguyen, Huu Phuc; Ellenbroek, Bart; Schreiber, Rudy
Chorea and psychiatric symptoms are hallmarks of Huntington disease (HD), a neurodegenerative disorder, genetically characterized by the presence of expanded CAG repeats (>35) in the HUNTINGTIN (HTT) gene. HD patients present psychiatric symptoms prior to the onset of motor symptoms and we recently found a similar emergence of non motor and motor deficits in BACHD rats carrying the human full length mutated HTT (97 CAG-CAA repeats). We evaluated cognitive performance in reversal learning and associative memory tests in different age cohorts of BACHD rats. Male wild type (WT) and transgenic (TG) rats between 2 and 12 months of age were tested. Learning and strategy shifting were assessed in a cross-maze test. Associative memory was evaluated in different fear conditioning paradigms (context, delay and trace). The possible confound of a fear conditioning phenotype by altered sensitivity to a ‘painful’ stimulus was assessed in a flinch-jump test. In the cross maze, 6 months old TG rats showed a mild impairment in reversal learning. In the fear conditioning tasks, 4, 6 and 12 months old TG rats showed a marked reduction in contextual fear conditioning. In addition, TG rats showed impaired delay conditioning (9 months) and trace fear conditioning (3 months). This phenotype was unlikely to be affected by a change in ‘pain’ sensitivity as WT and TG rats showed no difference in their threshold response in the flinch-jump test. Our results suggest that BACHD rats have a profound associative memory deficit and, possibly, a deficit in reversal learning as assessed in a cross maze task. The time course for the emergence of these symptoms (i.e., before the occurrence of motor symptoms) in this rat model for HD appears similar to the time course in patients. These data suggest that BACHD rats may be a useful model for preclinical drug discovery. PMID:24223692
Hylin, Michael J; Orsi, Sara A; Rozas, Natalia S; Hill, Julia L; Zhao, Jing; Redell, John B; Moore, Anthony N; Dash, Pramod K
Concussive force can cause neurocognitive and neurobehavioral dysfunction by inducing functional, electrophysiological, and/or ultrastructural changes within the brain. Although concussion-triggered symptoms typically subside within days to weeks in most people, in 15%-20% of the cases, symptomology can continue beyond this time point. Problems with memory, attention, processing speed, and cognitive flexibility (e.g., problem solving, conflict resolution) are some of the prominent post-concussive cognitive symptoms. Repeated concussions (with loss or altered consciousness), which are common to many contact sports, can exacerbate these symptoms. The pathophysiology of repeated concussions is not well understood, nor is an effective treatment available. In order to facilitate drug discovery to treat post-concussive symptoms (PCSs), there is a need to determine if animal models of repeated mild closed head injury (mCHI) can mimic the neurocognitive and histopathological consequences of repeated concussions. To this end, we employed a controlled cortical impact (CCI) device to deliver a mCHI directly to the skull of mice daily for 4 days, and examined the ensuing neurological and neurocognitive functions using beam balance, foot-fault, an abbreviated Morris water maze test, context discrimination, and active place avoidance tasks. Repeated mCHI exacerbated vestibulomotor, motor, short-term memory and conflict learning impairments as compared to a single mCHI. Learning and memory impairments were still observed in repeated mCHI mice when tested 3 months post-injury. Repeated mCHI also reduced cerebral perfusion, prolonged the inflammatory response, and in some animals, caused hippocampal neuronal loss. Our results show that repeated mCHI can reproduce some of the deficits seen after repeated concussions in humans and may be suitable for drug discovery studies and translational research.
Park, Alan J.; Tolentino, Rosa E.; Bruinenberg, Vibeke M.; Tudor, Jennifer C.; Lee, Yool; Hansen, Rolf T.; Guercio, Leonardo A.; Linton, Edward; Neves-Zaph, Susana R.; Meerlo, Peter; Baillie, George S.; Houslay, Miles D.
Alterations in cAMP signaling are thought to contribute to neurocognitive and neuropsychiatric disorders. Members of the cAMP-specific phosphodiesterase 4 (PDE4) family, which contains >25 different isoforms, play a key role in determining spatial cAMP degradation so as to orchestrate compartmentalized cAMP signaling in cells. Each isoform binds to a different set of protein complexes through its unique N-terminal domain, thereby leading to targeted degradation of cAMP in specific intracellular compartments. However, the functional role of specific compartmentalized PDE4 isoforms has not been examined in vivo. Here, we show that increasing protein levels of the PDE4A5 isoform in mouse hippocampal excitatory neurons impairs a long-lasting form of hippocampal synaptic plasticity and attenuates hippocampus-dependent long-term memories without affecting anxiety. In contrast, viral expression of a truncated version of PDE4A5, which lacks the unique N-terminal targeting domain, does not affect long-term memory. Further, overexpression of the PDE4A1 isoform, which targets a different subset of signalosomes, leaves memory undisturbed. Fluorescence resonance energy transfer sensor-based cAMP measurements reveal that the full-length PDE4A5, in contrast to the truncated form, hampers forskolin-mediated increases in neuronal cAMP levels. Our study indicates that the unique N-terminal localization domain of PDE4A5 is essential for the targeting of specific cAMP-dependent signaling underlying synaptic plasticity and memory. The development of compounds to disrupt the compartmentalization of individual PDE4 isoforms by targeting their unique N-terminal domains may provide a fruitful approach to prevent cognitive deficits in neuropsychiatric and neurocognitive disorders that are associated with alterations in cAMP signaling. SIGNIFICANCE STATEMENT Neurons exhibit localized signaling processes that enable biochemical cascades to be activated selectively in specific subcellular
Hirjak, Dusan; Wolf, Robert C; Remmele, Barbara; Seidl, Ulrich; Thomann, Anne K; Kubera, Katharina M; Schröder, Johannes; Maier-Hein, Klaus H; Thomann, Philipp A
Autobiographical memory (AM) is part of declarative memory and includes both semantic and episodic aspects. AM deficits are among the major complaints of patients with Alzheimer's disease (AD) even in early or preclinical stages. Previous MRI studies in AD patients have showed that deficits in semantic and episodic AM are associated with hippocampal alterations. However, the question which specific hippocampal subfields and adjacent extrahippocampal structures contribute to deficits of AM in individuals with mild cognitive impairment (MCI) and AD patients has not been investigated so far. Hundred and seven participants (38 AD patients, 38 MCI individuals and 31 healthy controls [HC]) underwent MRI at 3 Tesla. AM was assessed with a semi-structured interview (E-AGI). FreeSurfer 5.3 was used for hippocampal parcellation. Semantic and episodic AM scores were related to the volume of 5 hippocampal subfields and cortical thickness in the parahippocampal and entorhinal cortex. Both semantic and episodic AM deficits were associated with bilateral hippocampal alterations. These associations referred mainly to CA1, CA2-3, presubiculum, and subiculum atrophy. Episodic, but not semantic AM loss was associated with cortical thickness reduction of the bilateral parahippocampal and enthorinal cortex. In MCI individuals, episodic, but not semantic AM deficits were associated with alterations of the CA1, presubiculum and subiculum. Our findings support the crucial role of CA1, presubiculum, and subiculum in episodic memory. The present results implicate that in MCI individuals, semantic and episodic AM deficits are subserved by distinct neuronal systems.
Stanley, Dara A; Smith, Karen E; Raine, Nigel E
Bumblebees are exposed to pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb pesticide. These results indicate that field-realistic pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness.
Rubio, Julio; Qiong, Wang; Liu, Xinmin; Jiang, Zhen; Dang, Haixia; Chen, Shi-Lin; Gonzales, Gustavo F
The present study aims to test two different doses of aqueous extract of black maca on learning and memory in ovariectomized (OVX) mice and their relation with malonalehyde (MDA), acetylcholinesterase (Ache) and monoamine oxidase (MAO) brain levels. Female mice were divided into five groups: (i) naive (control), (ii) sham, (iii) OVX mice and OVX mice treated with (iv) 0.50 g kg(-1) and (v) 2.00 g kg(-1) black maca. Mice were orally treated with distilled water or black maca during 35 days starting 7 days after surgery. Memory and learning were assessed using the water Morris maze (from day 23-27) and the step-down avoidance test (days 34 and 35). At the end of each treatment, mice were sacrificed by decapitation and brains were dissected out for MDA, Ache and MAO determinations. Black maca (0.5 and 2.0 g/kg) increased step-down latency when compared to OVX control mice. Black maca decreased MDA and Ache levels in OVX mice; whereas, no differences were observed in MAO levels. Finally, black maca improved experimental memory impairment induced by ovariectomy, due in part, by its antioxidant and Ache inhibitory activities.
Abbasi, Esmail; Nassiri-Asl, Marjan; Sheikhi, Mehdi; Shafiee, Mahsa
Various synthetic derivatives of natural flavonoids are known to have neuroactive properties. The present study aimed to investigate the effects of vitexin (5, 7, 4-trihydroxyflavone-8-glucoside), a flavonoid found in such plants as tartary buckwheat sprouts, wheat leaves phenolome, Mimosa pudica Linn and Passiflora spp, on scopolamine-induced memory impairment in rats. To achieve this goal, we assessed the effects of vitexin on memory retrieval in the presence or absence of scopolamine using a step-through passive avoidance trial. In the first part of the study, vitexin (25, 50, and 100 microM) was administered intracerebroventricularly (i.c.v.) before acquisition trials. In the second part, vitexin, at the same doses, was administered before scopolamine (10 microg, i.c.v.) and before the acquisition trials. During retention tests, vitexin (100 microM) in the absence of scopolamine significantly increased the step-through latencies compared to scopolamine. In addition, vitexin (100 microM) significantly reversed the shorter step-through latencies induced by scopolamine (P < 0.05). These results indicate that vitexin has a potential role in enhancing memory retrieval. A possible mechanism is modulation of cholinergic receptors; however, other mechanisms may be involved in its effects in acute exposure.
Stanley, Dara A.; Smith, Karen E.; Raine, Nigel E.
Bumblebees are exposed to pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb pesticide. These results indicate that field-realistic pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness. PMID:26568480
Stine-Morrow, Elizabeth A. L.
Objectives. We examined the degree to which online sentence processing and offline sentence memory differed among older adults who showed risk for amnestic and nonamnestic varieties of mild cognitive impairment (MCI), based on psychometric classification. Method. Participants (N = 439) read a series of sentences in a self-paced word-by-word reading paradigm for subsequent recall and completed a standardized cognitive test battery. Participants were classified into 3 groups: unimpaired controls (N = 281), amnestic MCI (N = 94), or nonamnestic MCI (N = 64). Results. Relative to controls, both MCI groups had poorer sentence memory and showed reduced sentence wrap-up effects, indicating reduced allocation to semantic integration processes. Wrap-up effects predicted subsequent recall in the control and nonamnestic groups. The amnestic MCI group showed poorer recall than the nonamnestic MCI group, and only the amnestic MCI group showed no relationship between sentence wrap-up and recall. Discussion. Our findings suggest that psychometrically defined sub-types of MCI are associated with unique deficits in sentence processing and can differentiate between the engagement of attentional resources during reading and the effectiveness of engaging attentional resources in producing improved memory. PMID:25190209
Rhee, Soyoung; Kirschen, Gregory W.; Gu, Yan; Ge, Shaoyu
The primary cilium, a sensory organelle, regulates cell proliferation and neuronal development of dentate granule cells in the hippocampus. However, its role in the function of mature dentate granule cells remains unknown. Here we specifically depleted and disrupted ciliary proteins IFT20 and Kif3A (respectively) in mature dentate granule cells and investigated hippocampus-dependent contextual memory and long-term plasticity at mossy fiber synapses. We found that depletion of IFT20 in these cells significantly impaired context-dependent fear-related memory. Furthermore, we tested synaptic plasticity of mossy fiber synapses in area CA3 and found increased long-term potentiation upon depletion of IFT20 or disruption of Kif3A. Our findings suggest a role of primary cilia in the memory function of mature dentate granule cells, which may result from abnormal mossy fiber synaptic plasticity. A direct link between the primary cilia of mature dentate granule cells and behavior will require further investigation using independent approaches to manipulate primary cilia. PMID:27678193
Utkan, Tijen; Gocmez, Semil S; Regunathan, Soundararajan; Aricioglu, Feyza
Agmatine (l-amino-4-guanidino-butane), a metabolite of L-arginine through the action of arginine decarboxylase, is a novel neurotransmitter. In the present study, effects of agmatine on cognitive functions have been evaluated by using one trial step-down passive avoidance and three panel runway task. Agmatine (20, 40, 80 mg/kg i.p.) was administered either in the presence or absence of a cholinergic antagonist, scopolamine (1 mg/kg i.p.). Scopolamine significantly impaired learning and memory in both passive avoidance and three panel runway test. Agmatine did not affect emotional learning, working and reference memory but significantly improved scopolamine-induced impairment of learning and memory in a dose dependent manner. Our results indicate that agmatine, as an endogenous substance, may have an important role in modulation of learning and memory functions.
Bogaerts, Louisa; Szmalec, Arnaud; Hachmann, Wibke M; Page, Mike P A; Duyck, Wouter
The present study investigated long-term serial-order learning impairments, operationalized as reduced Hebb repetition learning (HRL), in people with dyslexia. In a first multi-session experiment, we investigated both the persistence of a serial-order learning impairment as well as the long-term retention of serial-order representations, both in a group of Dutch-speaking adults with developmental dyslexia and in a matched control group. In a second experiment, we relied on the assumption that HRL mimics naturalistic word-form acquisition and we investigated the lexicalization of novel word-forms acquired through HRL. First, our results demonstrate that adults with dyslexia are fundamentally impaired in the long-term acquisition of serial-order information. Second, dyslexic and control participants show comparable retention of the long-term serial-order representations in memory over a period of 1 month. Third, the data suggest weaker lexicalization of newly acquired word-forms in the dyslexic group. We discuss the integration of these findings into current theoretical views of dyslexia.
Barha, Cindy K; Galea, Liisa A M
Estrogens have been implicated as possible therapeutic agents for improving cognition in postmenopausal women and have been linked to neurodegenerative disorders such as Alzheimer's disease. However, the utility of Premarin (Wyeth Pharmaceuticals, Markham, ON, Canada), a conjugated equine estrogen and the most commonly prescribed hormone therapy, has recently been questioned. The purpose of this study was to investigate the effects of Premarin at 2 different doses (10 or 20 μg) on hippocampus-dependent spatial learning and memory, hippocampal neurogenesis, and new neuronal activation using a rodent model of surgical menopause. Rats were treated daily with subcutaneous injections of Premarin and trained on the spatial working/reference memory version of the radial arm maze. Premarin impaired spatial reference and working learning and memory, increased hippocampal neurogenesis, but either decreased or increased activation of new neurons in response to memory retrieval as indexed by the expression of the immediate early gene product zif268, depending on the maturity of cells examined. This activation of new neurons was related to impaired performance in Premarin-treated but not control-treated female rats. These results indicate that Premarin may be impairing hippocampus-dependent learning and memory by negatively altering the neurogenic environment in the dentate gyrus thus disrupting normal activity of new neurons.
Singh, Padmanabh; Konar, Arpita; Kumar, Ashish; Srivas, Sweta; Thakur, Mahendra K
The amnesic potential of scopolamine is well manifested through synaptic plasticity gene expression changes and behavioral paradigms of memory impairment. However, the underlying mechanism remains obscure and consequently ideal therapeutic target is lacking. In this context, chromatin-modifying enzymes, which regulate memory gene expression changes, deserve major attention. Therefore, we analyzed the expression of chromatin-modifying enzymes and recovery potential of enzyme modulators in scopolamine-induced amnesia. Scopolamine administration drastically up-regulated DNA methyltransferases (DNMT1) and HDAC2 expression while CREB-binding protein (CBP), DNMT3a and DNMT3b remained unaffected. HDAC inhibitor sodium butyrate and DNMT inhibitor Aza-2'deoxycytidine recovered scopolamine-impaired hippocampal-dependent memory consolidation with concomitant increase in the expression of synaptic plasticity genes Brain-derived neurotrophic factor (BDNF) and Arc and level of histone H3K9 and H3K14 acetylation and decrease in DNA methylation level. Sodium butyrate showed more pronounced effect than Aza-2'deoxycytidine and their co-administration did not exhibit synergistic effect on gene expression. Taken together, we showed for the first time that scopolamine-induced up-regulation of chromatin-modifying enzymes, HDAC2 and DNMT1, leads to gene expression changes and consequent decline in memory consolidation. Our findings on the action of scopolamine as an epigenetic modulator can pave a path for ideal therapeutic targets. We propose the following putative pathway for scopolamine-mediated memory impairment; scopolamine up-regulates hippocampal DNMT1 and HDAC2 expression, induces methylation and deacetylation of BDNF and Arc promoter, represses gene expression and eventually impairs memory consolidation. On the other hand, Aza-2 and NaB inhibit DNMT1 and HDAC2 respectively, up-regulate BDNF and Arc expression and recover memory consolidation. We elucidate the action of
Vasileva, Liliya V; Getova, Damianka P; Doncheva, Nina D; Marchev, Andrey S; Georgiev, Milen I
Rhodiola rosea L., family Crassulaceae also known as Golden Root or Arctic root is one of the most widely used medicinal plants with effect on cognitive dysfunction, psychological stress and depression. The aim of the study was to examine the effect of a standardized commercial Rhodiola extract on learning and memory processes in naive rats as well as its effects in rats with scopolamine-induced memory impairment.
The etiology of anorexia nervosa (AN) is still unclear, despite that it is a critical and potentially mortal illness. A recent neurobiological model considers AN as the outcome of dysfunctions in the neuronal processes related to appetite and emotionality (Kaye et al., 2009, 2013). However, this model still is not able to answer a critical question: What is behind body image disturbances (BIDs) in AN? The article starts its analysis from reviewing some of the studies exploring the effects of the serotonin systems in memory (episodic, working, and spatial) and its dysfunctions. The review suggests that serotonin disturbances may: (a) facilitate the encoding of third person (allocentric) episodic memories; (b) facilitate the consolidation of emotional episodic memories (e.g., teasing), if preceded by repeated stress; (c) reduce voluntary inhibition of mnestic contents; (d) impair allocentric spatial memory. If we discuss these results within the interpretative frame suggested by the “Allocentric Lock Hypothesis” (Riva, 2012, 2014), we can hypothesize that altered serotoninergic activity in AN patients: (i) improves their ability to store and consolidate negative autobiographical memories, including those of their body, in allocentric perspective; (ii) impairs their ability to trigger voluntary inhibition of the previously stored negative memory of the body; (iii) impairs their capacity to retrieve/update allocentric information. Taken together, these points suggest a possible link between serotonin dysfunctions, memory impairments and BIDs: the impossibility of updating a disturbed body memory using real time experiential data—I'm locked to a wrong body stored in long term memory—pushes AN patients to control body weight and shape even when underweight. PMID:27932968
Chen, Weiwei; Cheng, Xiang; Chen, Jinzhong; Yi, Xin; Nie, Dekang; Sun, Xiaohui; Qin, Jianbing; Tian, Meiling; Jin, Guohua; Zhang, Xinhua
Lycium barbarum is used both as a food additive and as a medicinal herb in many countries, and L. barbarum polysaccharides (LBPs), a major cell component, are reported to have a wide range of beneficial effects including neuroprotection, anti-aging and anticancer properties, and immune modulation. The effects of LBPs on neuronal function, neurogenesis, and drug-induced learning and memory deficits have not been assessed. We report the therapeutic effects of LBPs on learning and memory and neurogenesis in scopolamine (SCO)-treated rats. LBPs were administered via gastric perfusion for 2 weeks before the onset of subcutaneous SCO treatment for a further 4 weeks. As expected, SCO impaired performance in novel object and object location recognition tasks, and Morris water maze. However, dual SCO- and LBP-treated rats spent significantly more time exploring the novel object or location in the recognition tasks and had significant shorter escape latency in the water maze. SCO administration led to a decrease in Ki67- or DCX-immunoreactive cells in the dentate gyrus and damage of dendritic development of the new neurons; LBP prevented these SCO-induced reductions in cell proliferation and neuroblast differentiation. LBP also protected SCO-induced loss of neuronal processes in DCX-immunoreactive neurons. Biochemical investigation indicated that LBP decreased the SCO-induced oxidative stress in hippocampus and reversed the ratio Bax/Bcl-2 that exhibited increase after SCO treatment. However, decrease of BDNF and increase of AChE induced by SCO showed no response to LBP administration. These results suggest that LBPs can prevent SCO-induced cognitive and memory deficits and reductions in cell proliferation and neuroblast differentiation. Suppression of oxidative stress and apoptosis may be involved in the above effects of LBPs that may be a promising candidate to restore memory functions and neurogenesis.
Missonnier, P; Deiber, M-P; Gold, G; Herrmann, F R; Millet, P; Michon, A; Fazio-Costa, L; Ibañez, V; Giannakopoulos, P
Recent studies described several changes of endogenous event-related potentials (ERP) and brain rhythm synchronization during memory activation in patients with Alzheimer's disease (AD). To examine whether memory-related EEG parameters may predict cognitive decline in mild cognitive impairment (MCI), we assessed P200 and N200 latencies as well as beta event-related synchronization (ERS) in 16 elderly controls (EC), 29 MCI cases and 10 patients with AD during the successful performance of a pure attentional detection task as compared with a highly working memory demanding two-back task. At 1 year follow-up, 16 MCI patients showed progressive cognitive decline (PMCI) and 13 remained stable (SMCI). Both P200 and N200 latencies in the two-back task were longer in PMCI and AD cases compared with EC and SMCI cases. During the interval 1000 ms to 1700 ms after stimulus, beta ERS at parietal electrodes was of lower amplitude in PMCI and AD compared with EC and SMCI cases. Univariate models showed that P200, N200 and log% beta values were significantly related to the SMCI/PMCI distinction with areas under the receiver operating characteristic curve of 0.93, 0.78 and 0.72, respectively. The combination of all three EEG hallmarks was the stronger predictor of MCI deterioration with 90% of correctly classified MCI cases. Our data reveal that PMCI and clinically overt AD share the same pattern of working memory-related EEG activation characterized by increased P200-N200 latencies and decreased beta ERS. They also show that P200 latency during the two-back task may be a simple and promising EEG marker of rapid cognitive decline in MCI.
Chen, Jinzhong; Yi, Xin; Nie, Dekang; Sun, Xiaohui; Qin, Jianbing; Tian, Meiling; Jin, Guohua; Zhang, Xinhua
Lycium barbarum is used both as a food additive and as a medicinal herb in many countries, and L. barbarum polysaccharides (LBPs), a major cell component, are reported to have a wide range of beneficial effects including neuroprotection, anti-aging and anticancer properties, and immune modulation. The effects of LBPs on neuronal function, neurogenesis, and drug-induced learning and memory deficits have not been assessed. We report the therapeutic effects of LBPs on learning and memory and neurogenesis in scopolamine (SCO)-treated rats. LBPs were administered via gastric perfusion for 2 weeks before the onset of subcutaneous SCO treatment for a further 4 weeks. As expected, SCO impaired performance in novel object and object location recognition tasks, and Morris water maze. However, dual SCO- and LBP-treated rats spent significantly more time exploring the novel object or location in the recognition tasks and had significant shorter escape latency in the water maze. SCO administration led to a decrease in Ki67- or DCX-immunoreactive cells in the dentate gyrus and damage of dendritic development of the new neurons; LBP prevented these SCO-induced reductions in cell proliferation and neuroblast differentiation. LBP also protected SCO-induced loss of neuronal processes in DCX-immunoreactive neurons. Biochemical investigation indicated that LBP decreased the SCO-induced oxidative stress in hippocampus and reversed the ratio Bax/Bcl-2 that exhibited increase after SCO treatment. However, decrease of BDNF and increase of AChE induced by SCO showed no response to LBP administration. These results suggest that LBPs can prevent SCO-induced cognitive and memory deficits and reductions in cell proliferation and neuroblast differentiation. Suppression of oxidative stress and apoptosis may be involved in the above effects of LBPs that may be a promising candidate to restore memory functions and neurogenesis. PMID:24505383
Goodman, Jarid; Ressler, Reed L; Packard, Mark G
The present experiments investigated the involvement of N-methyl-d-aspartate (NMDA) receptors of the dorsolateral striatum (DLS) in consolidation of extinction in a habit memory task. Adult male Long-Evans rats were initially trained in a food-reinforced response learning version of a plus-maze task and were subsequently given extinction training in which the food was removed from the maze. In experiment 1, immediately after the first day of extinction training, rats received bilateral intra-DLS injections of the NMDA receptor antagonist 2-amino-5-phosphonopentanoic acid (AP5; 2µg/side) or physiological saline. In experiment 2, immediately following the first day of extinction training, animals were given intra-DLS injections of NMDA receptor partial agonist d-cycloserine (DCS; 10 or 20µg/side) or saline. In both experiments, the number of perseverative trials (a trial in which a rat made the same previously reinforced body-turn response) and latency to reach the previously correct food well were used as measures of extinction behavior. Results indicated that post-training intra-DLS injections of AP5 impaired extinction. In contrast, post-training intra-DLS infusions of DCS (20µg) enhanced extinction. Intra-DLS administration of AP5 or DCS given two hours after extinction training did not influence extinction of response learning, indicating that immediate post-training administration of AP5 and DCS specifically influenced consolidation of the extinction memory. The present results indicate a critical role for DLS NMDA receptors in modulating extinction of habit memory and may be relevant to developing therapeutic approaches to combat the maladaptive habits observed in human psychopathologies in which DLS-dependent memory has been implicated (e.g. drug addiction and relapse and obsessive compulsive disorder).
Clark, Lindsay R; Stricker, Nikki H; Libon, David J; Delano-Wood, Lisa; Salmon, David P; Delis, Dean C; Bondi, Mark W
Memory tests are sensitive to early identification of Alzheimer's disease (AD) but less useful as the disease advances. However, assessing particular types of recognition memory may better characterize dementia severity in later stages of AD. We sought to examine patterns of recognition memory deficits in individuals with AD and mild cognitive impairment (MCI). Memory performance and global cognition data were collected from participants with AD (n = 37), MCI (n = 37), and cognitively intact older adults (normal controls, NC; n = 35). One-way analyses of variance (ANOVAs) examined differences between groups on yes/no and forced-choice recognition measures. Individuals with amnestic MCI performed worse than NC and nonamnestic MCI participants on yes/no recognition, but were comparable on forced-choice recognition. AD patients were more impaired across yes/no and forced-choice recognition tasks. Individuals with mild AD (≥120 Dementia Rating Scale, DRS) performed better than those with moderate-to-severe AD (<120 DRS) on forced-choice recognition, but were equally impaired on yes/no recognition. There were differences in the relationships between learning, recall, and recognition performance across groups. Although yes/no recognition testing may be sensitive to MCI, forced-choice procedures may provide utility in assessing severity of anterograde amnesia in later stages of AD. Implications for assessment of insufficient effort and malingering are also discussed.
To investigate the features of electroencephalography (EEG) power and coherence at rest and during a working memory task of patients with mild cognitive impairment (MCI). Thirty-five patients (17 males, 18 females; 52-71 years old) and 34 sex- and age-matched controls (17 males, 17 females; 51-63 years old) were recruited in the present study. Mini-Mental State Examination (MMSE) of 35 patients with MCI and 34 normal controls revealed that the scores of MCI patients did not differ significantly from those of normal controls (P>0.05). Then, EEGs at rest and during working memory task with three levels of working memory load were recorded. The EEG power was computed over 10 channels: right and left frontal (F3, F4), central (C3, C4), parietal (P3, P4), temporal (T5, T6) and occipital (O1, O2); inter-hemispheric coherences were computed from five electrode pairs of F3-F4, C3-C4, P3-P4, T5-T6 and O1-O2 for delta (1.0-3.5 Hz), theta (4.0-7.5 Hz), alpha-1 (8.0-10.0 Hz), alpha-2 (10.5 -13.0 Hz), beta-1 (13.5-18.0 Hz) and beta-2 (18.5-30.0 Hz) frequency bands. All values of the EEG power of MCI patients were found to be higher than those of normal controls at rest and during working memory tasks. Furthermore, the values of EEG power in the theta, alpha-1, alpha-2 and beta-1 bands of patients with MCI were significantly high (P<0.05) in comparison with those of normal controls. Correlation analysis indicated a significant negative correlation between the EEG powers and MMSE scores. In addition, during working memory tasks, the EEG coherences in all bands were significantly higher in the MCI group in comparison with those in the control group (P<0.05). However, there was no significant difference in EEG coherences between two groups at rest. These findings comprise evidence that MCI patients have higher EEG power at rest, and higher EEG power and coherence during working conditions. It suggests that MCI may be associated with compensatory processes at rest and during working
Short-Term and Working Memory Skills in Primary School-Aged Children with Specific Language Impairment and Children with Pragmatic Language Impairment: Phonological, Linguistic and Visuo-Spatial Aspects
Freed, Jenny; Lockton, Elaine; Adams, Catherine
Background: Children with specific language impairment (CwSLI) are consistently reported to have short-term memory (STM) and working memory (WM) difficulties. Aim: To compare STM and WM abilities in CwSLI with children with pragmatic language impairment (CwPLI). Methods & Procedures: Primary school-aged CwSLI (n = 12) and CwPLI (n = 23) were…
Dodson, Chad S; Spaniol, Maggie; O'Connor, Maureen K; Deason, Rebecca G; Ally, Brandon A; Budson, Andrew E
We assessed the ability of two groups of patients with mild Alzheimer's disease (AD) and two groups of older adults to monitor the likely accuracy of recognition judgments and source identification judgments about who spoke something earlier. Alzheimer's patients showed worse performance on both memory judgments and were less able to monitor with confidence ratings the likely accuracy of both kinds of memory judgments, as compared to a group of older adults who experienced the identical study and test conditions. Critically, however, when memory performance was made comparable between the AD patients and the older adults (e.g., by giving AD patients extra exposures to the study materials), AD patients were still greatly impaired at monitoring the likely accuracy of their recognition and source judgments. This result indicates that the monitoring impairment in AD patients is actually worse than their memory impairment, as otherwise there would have been no differences between the two groups in monitoring performance when there were no differences in accuracy. We discuss the brain correlates of this memory-monitoring deficit and also propose a Remembrance-Evaluation model of memory-monitoring.
Hattiangady, Bharathi; Mishra, Vikas; Kodali, Maheedhar; Shuai, Bing; Rao, Xiolan; Shetty, Ashok K.
Memory and mood deficits are the enduring brain-related symptoms in Gulf War illness (GWI). Both animal model and epidemiological investigations have indicated that these impairments in a majority of GW veterans are linked to exposures to chemicals such as pyridostigmine bromide (PB, an antinerve gas drug), permethrin (PM, an insecticide) and DEET (a mosquito repellant) encountered during the Persian Gulf War-1. Our previous study in a rat model has shown that combined exposures to low doses of GWI-related (GWIR) chemicals PB, PM, and DEET with or without 5-min of restraint stress (a mild stress paradigm) causes hippocampus-dependent spatial memory dysfunction in a water maze test (WMT) and increased depressive-like behavior in a forced swim test (FST). In this study, using a larger cohort of rats exposed to GWIR-chemicals and stress, we investigated whether the memory deficiency identified earlier in a WMT is reproducible with an alternative and stress free hippocampus-dependent memory test such as the object location test (OLT). We also ascertained the possible co-existence of hippocampus-independent memory dysfunction using a novel object recognition test (NORT), and alterations in mood function with additional tests for motivation and depression. Our results provide new evidence that exposure to low doses of GWIR-chemicals and mild stress for 4 weeks causes deficits in hippocampus-dependent object location memory and perirhinal cortex-dependent novel object recognition memory. An open field test performed prior to other behavioral analyses revealed that memory impairments were not associated with increased anxiety or deficits in general motor ability. However, behavioral tests for mood function such as a voluntary physical exercise paradigm and a novelty suppressed feeding test (NSFT) demonstrated decreased motivation levels and depression. Thus, exposure to GWIR-chemicals and stress causes both hippocampus-dependent and hippocampus-independent memory
Hattiangady, Bharathi; Mishra, Vikas; Kodali, Maheedhar; Shuai, Bing; Rao, Xiolan; Shetty, Ashok K
Memory and mood deficits are the enduring brain-related symptoms in Gulf War illness (GWI). Both animal model and epidemiological investigations have indicated that these impairments in a majority of GW veterans are linked to exposures to chemicals such as pyridostigmine bromide (PB, an antinerve gas drug), permethrin (PM, an insecticide) and DEET (a mosquito repellant) encountered during the Persian Gulf War-1. Our previous study in a rat model has shown that combined exposures to low doses of GWI-related (GWIR) chemicals PB, PM, and DEET with or without 5-min of restraint stress (a mild stress paradigm) causes hippocampus-dependent spatial memory dysfunction in a water maze test (WMT) and increased depressive-like behavior in a forced swim test (FST). In this study, using a larger cohort of rats exposed to GWIR-chemicals and stress, we investigated whether the memory deficiency identified earlier in a WMT is reproducible with an alternative and stress free hippocampus-dependent memory test such as the object location test (OLT). We also ascertained the possible co-existence of hippocampus-independent memory dysfunction using a novel object recognition test (NORT), and alterations in mood function with additional tests for motivation and depression. Our results provide new evidence that exposure to low doses of GWIR-chemicals and mild stress for 4 weeks causes deficits in hippocampus-dependent object location memory and perirhinal cortex-dependent novel object recognition memory. An open field test performed prior to other behavioral analyses revealed that memory impairments were not associated with increased anxiety or deficits in general motor ability. However, behavioral tests for mood function such as a voluntary physical exercise paradigm and a novelty suppressed feeding test (NSFT) demonstrated decreased motivation levels and depression. Thus, exposure to GWIR-chemicals and stress causes both hippocampus-dependent and hippocampus-independent memory
O'Hara, Ruth; Derouesné, Christian; Fountoulakis, Konstantinos N.; Yesavage, Jerome A.
The United Nations projects that the number of individuals with dementia in developed countries alone will be approximately 36,7 million by the year 2050. International recognition of the significant emotional and economic burden of Alzheimer's disease has been matched by a dramatic increase in the development of pharmacological and nonpharmacological approaches to this illness in the past decade. Changing demographics have underscored the necessity to develop similar approaches for the remediation of the cognitive impairment associated with more benign syndromes, such as mild cognitive impairment (MCI) and age-associated cognitive decline (AACD). The present article aims to provide an overview of the most current therapeutic approaches to age-associated neurocognitive disorders. Additionally, it discusses the conceptual and methodological issues that surround the design, implementation, and interpretation of such approaches. PMID:22033831
Dwivedi, Subhash; Rajasekar, N; Hanif, Kashif; Nath, Chandishwar; Shukla, Rakesh
Okadaic acid (OKA) causes memory impairment and attenuates nuclear factor erythroid 2-related factor 2 (Nrf2) along with oxidative stress and neuroinflammation in rats. Sulforaphane (dietary isothiocyanate compound), an activator of Nrf2 signaling, exhibits neuroprotective effects. However, the protective effect of sulforaphane in OKA-induced neurotoxicity remains uninvestigated. Therefore, in the present study, the role of sulforaphane in OKA-induced memory impairment in rats was explored. A significant increased Nrf2 expression in the hippocampus and cerebral cortex was observed in trained (Morris water maze) rats, and a significant decreased Nrf2 expression in memory-impaired (OKA, 200 ng icv) rats indicated its involvement in memory function. Sulforaphane administration (5 and 10 mg/kg, ip, days 1 and 2) ameliorates OKA-induced memory impairment in rats. The treatment also restored Nrf2 and its downstream antioxidant protein expression (GCLC, HO-1) and attenuated oxidative stress (ROS, nitrite, GSH), neuroinflammation (NF-κB, TNF-α, IL-10), and neuronal apoptosis in the cerebral cortex and hippocampus of OKA-treated rats. Further, to determine whether modulation of Nrf2 signaling is responsible for the protective effect of sulforaphane, in vitro, Nrf2 siRNA and its downstream HO-1 inhibition studies were carried out in a rat astrocytoma cell line (C6). The protective effects of sulforaphane were abolished with Nrf2 siRNA and HO-1 inhibition in astrocytes. The results suggest that Nrf2-dependent activation of cellular antioxidant machinery results in sulforaphane-mediated protection against OKA-induced memory impairment in rats. Graphical Abstract ᅟ.
Schutsky, Keith; Ouyang, Ming; Castelino, Christina B; Zhang, Lei; Thomas, Steven A
Acute stress impairs the retrieval of hippocampus-dependent memory, and this effect is mimicked by exogenous administration of stress-responsive glucocorticoid hormones. It has been proposed that glucocorticoids affect memory by promoting the release and/or blocking the reuptake of norepinephrine (NE), a stress-responsive neurotransmitter. It has also been proposed that this enhanced NE signaling impairs memory retrieval by stimulating β(1)-adrenergic receptors and elevating levels of cAMP. In contrast, other evidence indicates that NE, β(1), and cAMP signaling is transiently required for the retrieval of hippocampus-dependent memory. To resolve this discrepancy, wild-type rats and mice with and without gene-targeted mutations were stressed or treated with glucocorticoids and/or adrenergic receptor drugs before testing memory for inhibitory avoidance or fear conditioning. Here we report that glucocorticoids do not require NE to impair retrieval. However, stress- and glucocorticoid-induced impairments of retrieval depend on the activation of β(2) (but not β(1))-adrenergic receptors. Offering an explanation for the opposing functions of these two receptors, the impairing effects of stress, glucocorticoids and β(2) agonists on retrieval are blocked by pertussis toxin, which inactivates signaling by G(i/o)-coupled receptors. In hippocampal slices, β(2) signaling decreases cAMP levels and greatly reduces the increase in cAMP mediated by β(1) signaling. Finally, augmenting cAMP signaling in the hippocampus prevents the impairment of retrieval by systemic β(2) agonists or glucocorticoids. These results demonstrate that the β(2) receptor can be a critical effector of acute stress, and that β(1) and β(2) receptors can have quite distinct roles in CNS signaling and cognition.
Korotkova, Tatiana; Fuchs, Elke C; Ponomarenko, Alexey; von Engelhardt, Jakob; Monyer, Hannah
Activity of parvalbumin-positive hippocampal interneurons is critical for network synchronization but the receptors involved therein have remained largely unknown. Here we report network and behavioral deficits in mice with selective ablation of NMDA receptors in parvalbumin-positive interneurons (NR1(PVCre-/-)). Recordings of local field potentials and unitary neuronal activity in the hippocampal CA1 area revealed altered theta oscillations (5-10 Hz) in freely behaving NR1(PVCre-/-) mice. Moreover, in contrast to controls, in NR1(PVCre-/-) mice the remaining theta rhythm was abolished by the administration of atropine. Gamma oscillations (35-85 Hz) were increased and less modulated by the concurrent theta rhythm in the mutant. Positional firing of pyramidal cells in NR1(PVCre-/-) mice was less spatially and temporally precise. Finally, NR1(PVCre-/-) mice exhibited impaired spatial working as well as spatial short- and long-term recognition memory but showed no deficits in open field exploratory activity and spatial reference learning.
Wang, Qin; Xu, Zhiqiang; Tang, Jinrong; Sun, Jianguo; Gao, Junying; Wu, Ting; Xiao, Ming
Exercise has been shown to enhance hippocampus-related cognition and slow the progression of Alzheimer's disease (AD). However, whether voluntary exercise directly decreases the neurotoxicity of amyloid peptide (Aβ) needs to be determined. In the present study, two-month old male C57bl/6 mice were intracerebroventricularly injected with Aβ25-35, and then allowed for voluntary exercise for 12 days. Y-maze test revealed that voluntary exercise mitigated spatial memory impairment induced by Aβ25-35. Consistently, Aβ25-35 treated mice with exercise showed reduced neuronal degeneration and synaptic protein loss in the hippocampus compared with sedentary controls. Moreover, voluntary exercise significantly ameliorated oxidative stress markers and increased vessel branches in the hippocampus of Aβ25-35 treated mice. Our results suggest that voluntary exercise counteracts the neurotoxicity of Aβ by reducing oxidative stress and increasing angiogenesis, which may underlie the beneficial effect of exercise on AD.
Hoshino, Takatoshi; Tanno, Yoshihiko
The present study investigated whether the control of reflective attention in working memory (WM) is impaired in high trait anxiety individuals. We focused on the consequences of refreshing-a simple reflective process of thinking briefly about a just-activated representation in mind-on the subsequent processing of verbal stimuli. Participants performed a selective refreshing task, in which they initially refreshed or read one word from a three-word set, and then refreshed a non-selected item from the initial phrase or read aloud a new word. High trait anxiety individuals exhibited greater latencies when refreshing a word after experiencing the refreshing of a word from the same list of semantic associates. The same pattern was observed for reading a new word after prior refreshing. These findings suggest that high trait anxiety individuals have difficulty resolving interference from active distractors when directing reflective attention towards contents in WM or processing a visually presented word.
AhnAllen, Christopher G.; Nestor, Paul G.; McCarley, Robert W.; Shenton, Martha E.
To examine retrieval-induced forgetting (RIF) in schizophrenia, subjects studied category-exemplar words taken from either strong or weak categories, and then practiced retrieval by completing category word-stems on half of the word pairs. Patients had reduced recall and recognition, but showed the expected RIF effect of better recall of unpracticed items from unpracticed categories than for unpracticed items from practiced categories. By contrast, patients and controls showed differing RIF for recognition as a function of categorical dominance: whereas controls showed RIF only for dominant category exemplar word pairs, patients showed RIF for both dominant and weak categories. Different patterns of baseline practiced retrieval for weak associate pairs in schizophrenia may explain this finding. The results failed to support faulty RIF in the associative memory impairment of schizophrenia. PMID:17188366
Moro, V; Condoleo, M T; Valbusa, V; Broggio, E; Moretto, G; Gambina, G
Executive functions play an important role in the maintenance of autonomy in day-to-day activities. Nevertheless, there is little research into specific cognitive training for Mild Cognitive Impairment (MCI). We present the results of a program which aims to teach specific strategies and metacognitive abilities in order for patients to be able to carry out attentional and executive tasks. Two groups (A and B) were compared in a cross-over design. After the first evaluation, Group A (but not B) participated in a six month cognitive stimulation program. After a second assessment, only Group B received treatment and then a final evaluation was carried out on both groups. The results show that: i) both groups improved their performance as an effect of training; ii) improvements generalized to memory and general cognitive tasks; iii) in the interval without training, Group B's performance worsened and iv) Group A partially maintained their results over time.
Albouy, Philippe; Cousineau, Marion; Caclin, Anne; Tillmann, Barbara; Peretz, Isabelle
Recent theories suggest that the basis of neurodevelopmental auditory disorders such as dyslexia or specific language impairment might be a low-level sensory dysfunction. In the present study we test this hypothesis in congenital amusia, a neurodevelopmental disorder characterized by severe deficits in the processing of pitch-based material. We manipulated the temporal characteristics of auditory stimuli and investigated the influence of the time given to encode pitch information on participants’ performance in discrimination and short-term memory. Our results show that amusics’ performance in such tasks scales with the duration available to encode acoustic inf