Kawamura, Osamu; Easterling, Caryn; Rittmann, Tanya; Hofmann, Candy; Shaker, Reza
To determine the optimal air stimulus intensity and duration for elicitation of the laryngo-upper esophageal sphincter (UES) contractile reflex, we studied 37 healthy volunteers 20 to 81 years of age. A sleeve device monitored the UES pressure. For laryngeal stimulation, we used an air stimulator unit (Pentax AP-4000) that incorporated a nasolaryngeal endoscope. The arytenoids and interarytenoid areas were stimulated at least three times by three different stimuli: 6-mm Hg air pulse with 50-ms duration, 10-mm Hg air pulse with 50-ms duration, and 6-mm Hg air pulse with 2-second duration. Of 1,165 air stimulations, 1,041 resulted in mucosal deflections. Of these, 451 resulted in an abrupt increase in UES pressure. The response/deflection ratio for 6-mm Hg stimulation with 2-second duration was significantly higher than those for air pulses with 50-ms duration (p < .001). We conclude that although the laryngo-UES contractile reflex can be elicited by an air pulse with 50-ms duration, this ultrashort stimulation is not reliable. Using longer-duration pulses (at least 2 seconds) improves the reliability of elicitation of the laryngo-UES contractile reflex.
Gee, Dylan Grace; Goff, Bonnie; Flannery, Jessica; Telzer, Eva; Humphreys, Kathryn Leigh; Lumian, Daniel Stephen; Fareri, Dominic Stephen; Caldera, Christina; Tottenham, Nim
Although the functional architecture of the brain is indexed by resting-state connectivity networks, little is currently known about the mechanisms through which these networks assemble into stable mature patterns. The current study posits and tests the long-term phasic molding hypothesis that resting-state networks are gradually shaped by recurring stimulus-elicited connectivity across development by examining how both stimulus-elicited and resting-state functional connections of the human brain emerge over development at the systems level. Using a sequential design following 4- to 18-year-olds over a 2 year period, we examined the predictive associations between stimulus-elicited and resting-state connectivity in amygdala-cortical circuitry as an exemplar case (given this network's protracted development across these ages). Age-related changes in amygdala functional connectivity converged on the same regions of medial prefrontal cortex (mPFC) and inferior frontal gyrus when elicited by emotional stimuli and when measured at rest. Consistent with the long-term phasic molding hypothesis, prospective analyses for both connections showed that the magnitude of an individual's stimulus-elicited connectivity unidirectionally predicted resting-state functional connectivity 2 years later. For the amygdala-mPFC connection, only stimulus-elicited connectivity during childhood and the transition to adolescence shaped future resting-state connectivity, consistent with a sensitive period ending with adolescence for the amygdala-mPFC circuit. Together, these findings suggest that resting-state functional architecture may arise from phasic patterns of functional connectivity elicited by environmental stimuli over the course of development on the order of years. SIGNIFICANCE STATEMENT A fundamental issue in understanding the ontogeny of brain function is how resting-state (intrinsic) functional networks emerge and relate to stimulus-elicited functional connectivity. Here, we
Colson, Violaine; Party, Virginie; Renou, Michel; Anderson, Peter; Gadenne, Christophe; Marion-Poll, Frédéric; Anton, Sylvia
The effect of repeated exposure to sensory stimuli, with or without reward is well known to induce stimulus-specific modifications of behaviour, described as different forms of learning. In recent studies we showed that a brief single pre-exposure to the female-produced sex pheromone or even a predator sound can increase the behavioural and central nervous responses to this pheromone in males of the noctuid moth Spodoptera littoralis. To investigate if this increase in sensitivity might be restricted to the pheromone system or is a form of general sensitization, we studied here if a brief pre-exposure to stimuli of different modalities can reciprocally change behavioural and physiological responses to olfactory and gustatory stimuli. Olfactory and gustatory pre-exposure and subsequent behavioural tests were carried out to reveal possible intra- and cross-modal effects. Attraction to pheromone, monitored with a locomotion compensator, increased after exposure to olfactory and gustatory stimuli. Behavioural responses to sucrose, investigated using the proboscis extension reflex, increased equally after pre-exposure to olfactory and gustatory cues. Pheromone-specific neurons in the brain and antennal gustatory neurons did, however, not change their sensitivity after sucrose exposure. The observed intra- and reciprocal cross-modal effects of pre-exposure may represent a new form of stimulus-nonspecific general sensitization originating from modifications at higher sensory processing levels. PMID:22457821
Kafashan, MohammadMehdi; Ching, ShiNung
Objective. We consider the problem of optimal probing to learn connections in an evoked dynamic network. Such a network, in which each edge measures an input-output relationship between sites in sensor/actuator-space, is relevant to emerging applications in neural mapping and neural connectivity estimation. Approach. We show that the problem of scheduling nodes to a probe (i.e., stimulate) amounts to a problem of optimal sensor scheduling. Main results. By formulating the evoked network in state-space, we show that the solution to the greedy probing strategy has a convenient form and, under certain conditions, is optimal over a finite horizon. We adopt an expectation maximization technique to update the state-space parameters in an online fashion and demonstrate the efficacy of the overall approach in a series of detailed numerical examples. Significance. The proposed method provides a principled means to actively probe time-varying connections in neuronal networks. The overall method can be implemented in real time and is particularly well-suited to applications in stimulation-based cortical mapping in which the underlying network dynamics are changing over time.
Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Acock, Keena; DeDios, Yiri E.; Heap, Erin; Peters, Brian; Wood, Scott; Serrador, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob
Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant sensory signals. Recent studies have shown that applying imperceptible stochastic noise electrical stimulation to the vestibular system significantly improved balance and ocular motor responses. The goal of this study was to optimize the amplitude of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standardized balance task of standing on a block of 10-cm-thick medium-density foam with their eyes closed. Balance performance was measured using a force plate under the foam block and using inertial motion sensors placed on the torso and head segments. Stochastic electrical stimulation was applied to the vestibular system through electrodes placed over the mastoid process. Subjects were tested at seven amplitudes in the 0.01-30Hz frequency range. The root mean square of the signal increased by 30 microamperes for each +/-100 microampere increment in the current range of 0 - +/-700 microampere. Six balance parameters were calculated to characterize the performance of subjects during the baseline and the stimulus periods for all seven amplitudes. Optimal stimulus amplitude was determined as the one at which the ratio of parameters from the stimulus period to the baseline period for any amplitude range was less than that for the no stimulus condition on a minimum of four of six parameters. Results from this study showed that balance performance at the optimal stimulus amplitude showed significant improvement with the application of the vestibular SR stimulation. The amplitude of optimal stimulus for improving balance performance in normal subjects was in the range of +/-100 - +/-300 microamps.
Chambers, Anna R; Hancock, Kenneth E; Sen, Kamal; Polley, Daniel B
Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions. To further characterize how auditory cortical neurons decompose and integrate multiple facets of an isolated sound, we developed an automated procedure that manipulated five fundamental acoustic properties in real time based on single-unit feedback in awake mice. Within several minutes, the online approach converged on regions of the multidimensional stimulus manifold that reliably drove neurons at significantly higher rates than predefined stimuli. Optimized stimuli were cross-validated against pure tone receptive fields and spectrotemporal receptive field estimates in the inferior colliculus and primary auditory cortex. We observed, from midbrain to cortex, increases in both level invariance and frequency selectivity, which may underlie equivalent sparseness of responses in the two areas. We found that onset and steady-state spike rates increased proportionately as the stimulus was tailored to the multidimensional receptive field. By separately evaluating the amount of leverage each sound feature exerted on the overall firing rate, these findings reveal interdependencies between stimulus features as well as hierarchical shifts in selectivity and invariance that may go unnoticed with traditional approaches.
Hancock, Kenneth E.; Sen, Kamal
Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions. To further characterize how auditory cortical neurons decompose and integrate multiple facets of an isolated sound, we developed an automated procedure that manipulated five fundamental acoustic properties in real time based on single-unit feedback in awake mice. Within several minutes, the online approach converged on regions of the multidimensional stimulus manifold that reliably drove neurons at significantly higher rates than predefined stimuli. Optimized stimuli were cross-validated against pure tone receptive fields and spectrotemporal receptive field estimates in the inferior colliculus and primary auditory cortex. We observed, from midbrain to cortex, increases in both level invariance and frequency selectivity, which may underlie equivalent sparseness of responses in the two areas. We found that onset and steady-state spike rates increased proportionately as the stimulus was tailored to the multidimensional receptive field. By separately evaluating the amount of leverage each sound feature exerted on the overall firing rate, these findings reveal interdependencies between stimulus features as well as hierarchical shifts in selectivity and invariance that may go unnoticed with traditional approaches. PMID:24990917
Choi, John S.; Brockmeier, Austin J.; McNiel, David B.; von Kraus, Lee M.; Príncipe, José C.; Francis, Joseph T.
Objective. Lost sensations, such as touch, could one day be restored by electrical stimulation along the sensory neural pathways. Such stimulation, when informed by electronic sensors, could provide naturalistic cutaneous and proprioceptive feedback to the user. Perceptually, microstimulation of somatosensory brain regions produces localized, modality-specific sensations, and several spatiotemporal parameters have been studied for their discernibility. However, systematic methods for encoding a wide array of naturally occurring stimuli into biomimetic percepts via multi-channel microstimulation are lacking. More specifically, generating spatiotemporal patterns for explicitly evoking naturalistic neural activation has not yet been explored. Approach. We address this problem by first modeling the dynamical input-output relationship between multichannel microstimulation and downstream neural responses, and then optimizing the input pattern to reproduce naturally occurring touch responses as closely as possible. Main results. Here we show that such optimization produces responses in the S1 cortex of the anesthetized rat that are highly similar to natural, tactile-stimulus-evoked counterparts. Furthermore, information on both pressure and location of the touch stimulus was found to be highly preserved. Significance. Our results suggest that the currently presented stimulus optimization approach holds great promise for restoring naturalistic levels of sensation.
Oby, Emily R.; Perel, Sagi; Sadtler, Patrick T.; Ruff, Douglas A.; Mischel, Jessica L.; Montez, David F.; Cohen, Marlene R.; Batista, Aaron P.; Chase, Steven M.
Objective. A traditional goal of neural recording with extracellular electrodes is to isolate action potential waveforms of an individual neuron. Recently, in brain-computer interfaces (BCIs), it has been recognized that threshold crossing events of the voltage waveform also convey rich information. To date, the threshold for detecting threshold crossings has been selected to preserve single-neuron isolation. However, the optimal threshold for single-neuron identification is not necessarily the optimal threshold for information extraction. Here we introduce a procedure to determine the best threshold for extracting information from extracellular recordings. We apply this procedure in two distinct contexts: the encoding of kinematic parameters from neural activity in primary motor cortex (M1), and visual stimulus parameters from neural activity in primary visual cortex (V1). Approach. We record extracellularly from multi-electrode arrays implanted in M1 or V1 in monkeys. Then, we systematically sweep the voltage detection threshold and quantify the information conveyed by the corresponding threshold crossings. Main Results. The optimal threshold depends on the desired information. In M1, velocity is optimally encoded at higher thresholds than speed; in both cases the optimal thresholds are lower than are typically used in BCI applications. In V1, information about the orientation of a visual stimulus is optimally encoded at higher thresholds than is visual contrast. A conceptual model explains these results as a consequence of cortical topography. Significance. How neural signals are processed impacts the information that can be extracted from them. Both the type and quality of information contained in threshold crossings depend on the threshold setting. There is more information available in these signals than is typically extracted. Adjusting the detection threshold to the parameter of interest in a BCI context should improve our ability to decode motor intent
Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J.J.; Mulavara, A.P.
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface . This technique to improve detection of vestibular signals uses a stimulus delivery system that provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for sensorimotor adaptability (SA) training applications customized to each crewmember. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds . We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s long sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. Comparison of threshold of motion detection obtained from joystick data versus body sway suggests that perceptual thresholds were significantly lower. In the balance task, subjects stood on an unstable surface and had to maintain balance
Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Cohen, H.; Bloomberg, J. J.; Mulavara, A. P.
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). Our previous work has shown the advantageous effects of VSR in a balance task of standing on an unstable surface. This technique to improve detection of vestibular signals uses a stimulus delivery system that is wearable or portable and provides imperceptibly low levels of white noise-based binaural bipolar electrical stimulation of the vestibular system. The goal of this project is to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection. A series of experiments were carried out to determine a robust paradigm to identify a vestibular threshold that can then be used to recommend optimal stimulation levels for SR training applications customized to each crewmember. Customizing stimulus intensity can maximize treatment effects. The amplitude of stimulation to be used in the VSR application has varied across studies in the literature such as 60% of nociceptive stimulus thresholds. We compared subjects' perceptual threshold with that obtained from two measures of body sway. Each test session was 463s long and consisted of several 15s sinusoidal stimuli, at different current amplitudes (0-2 mA), interspersed with 20-20.5s periods of no stimulation. Subjects sat on a chair with their eyes closed and had to report their perception of motion through a joystick. A force plate underneath the chair recorded medio-lateral shear forces and roll moments. First we determined the percent time during stimulation periods for which perception of motion (activity above a pre-defined threshold) was reported using the joystick, and body sway (two
Marcos, J L; Redondo, J
Previous research on electrodermal conditioning suggests that the conditioned diminution of the unconditioned response (UR) has an associative basis. The aim of this experiment was to test whether this phenomenon also occurs in heart rate (HR) classical conditioning. For this purpose, a differential classical conditioning was performed. The conditioned stimuli (CSs) were geometrical shapes (the CS+ was a square and the CS- was a triangle) displayed on a computer screen and a burst of white noise was used as unconditioned stimulus (US). For analysis of the conditioned response (CR) components, an interval between CS+ and US of 8 seconds was used. After the acquisition phase, participants were tested using trials with the US preceded either by a CS+, a CS-, or a neutral stimulus (a circle). The results showed conditioned diminution of the UR and suggest that the second heart rate deceleration component (D2) is responsible for the occurrence of this phenomenon.
Mulavara, Ajitkumar; Fiedler, Matthew; Kofman, Igor; Peters, Brian; Wood, Scott; Serrador, Jorge; Cohen, Helen; Reschke, Millard; Bloomberg, Jacob
Stochastic resonance (SR) is a mechanism by which noise can assist and enhance the response of neural systems to relevant sensory signals. Application of imperceptible SR noise coupled with sensory input through the proprioceptive, visual, or vestibular sensory systems has been shown to improve motor function. Specifically, studies have shown that that vestibular electrical stimulation by imperceptible stochastic noise, when applied to normal young and elderly subjects, significantly improved their ocular stabilization reflexes in response to whole-body tilt as well as balance performance during postural disturbances. The goal of this study was to optimize the characteristics of the stochastic vestibular signals for balance performance during standing on an unstable surface. Subjects performed a standardized balance task of standing on a block of 10 cm thick medium density foam with their eyes closed for a total of 40 seconds. Stochastic electrical stimulation was applied to the vestibular system through electrodes placed over the mastoid process behind the ears during the last 20 seconds of the test period. A custom built constant current stimulator with subject isolation delivered the stimulus. Stimulation signals were generated with frequencies in the bandwidth of 1-2 Hz and 0.01-30 Hz. Amplitude of the signals were varied in the range of 0- +/-700 micro amperes with the RMS of the signal increased by 30 micro amperes for each 100 micro amperes increase in the current range. Balance performance was measured using a force plate under the foam block and inertial motion sensors placed on the torso and head segments. Preliminary results indicate that balance performance is improved in the range of 10-25% compared to no stimulation conditions. Subjects improved their performance consistently across the blocks of stimulation. Further the signal amplitude at which the performance was maximized was different in the two frequency ranges. Optimization of the frequency and
Baenas, Nieves; Villaño, Debora; García-Viguera, Cristina; Moreno, Diego A
Elicitation is a cheaper and socially acceptable tool for improving plant food functionality. Our objective was to optimize the treatment doses of the elicitors: methyl jasmonate (MeJA), jasmonic acid (JA) and DL-methionine (MET), in order to find a successful and feasible treatment to produce broccoli and radish sprouts with enhanced levels of health-promoting glucosinolates. Also a priming of seeds as a novel strategy to trigger the glucosinolates content was carried out with water (control), MeJA (250μM), JA (250μM) and MET (10mM) before the elicitor exogenous treatment. The results showed that almost all treatments could enhance effectively the total glucosinolates content in the sprouts, achieving the most significant increases from 34% to 100% of increase in broccoli and from 45% to 118% of increase in radish sprouts after MeJA priming and treatments. Consequently, our work demonstrates the feasibility of using elicitors, such as plant stress hormones, by priming and exogenously, as a way of increase the phytochemical profile of these sprouts to enhance their consumption in the diet.
Radzikowska, Zofia; Milanowski, Piotr; Kuś, Rafał; Suffczyński, Piotr; Michalska, Magdalena; Łabęcki, Maciej; Zwoliński, Piotr; Durka, Piotr
Efforts to construct an effective brain-computer interface (BCI) system based on Steady State Visual Evoked Potentials (SSVEP) commonly focus on sophisticated mathematical methods for data analysis. The role of different stimulus features in evoking strong SSVEP is less often considered and the knowledge on the optimal stimulus properties is still fragmentary. The goal of this study was to provide insight into the influence of stimulus characteristics on the magnitude of SSVEP response. Five stimuli parameters were tested: size, distance, colour, shape, and presence of a fixation point in the middle of each flickering field. The stimuli were presented on four squares on LCD screen, with each square highlighted by LEDs flickering with different frequencies. Brighter colours and larger dimensions of flickering fields resulted in a significantly stronger SSVEP response. The distance between stimulation fields and the presence or absence of the fixation point had no significant effect on the response. Contrary to a popular belief, these results suggest that absence of the fixation point does not reduce the magnitude of SSVEP response. However, some parameters of the stimuli such as colour and the size of the flickering field play an important role in evoking SSVEP response, which indicates that stimuli rendering is an important factor in building effective SSVEP based BCI systems. PMID:25398134
to a mechanical slide via a rack and pinion mechanism (gear diameter= 0.438”). Precise control of the mechanism was achieved via control of the...with parameters that describe their associated temporal dynamics and relations to the observed output. A description of the model follows, but we...was meant to select the unit with the most unambiguous touch-stimulus- tuning. Then, a global gain was applied to the representative PSTHs to produce
Diezel, Celia; Allmann, Silke; Baldwin, Ian T
To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness costs. Three phytohormones, jasmonates (JA) and their active forms, the JA-isoleucine (JA-Ile) and ethylene (ET), are known to play central roles in the elicitation of induced defenses, but little is known about how this mediation changes over ontogeny. The Optimal Defense Theory (ODT) predicts changes in the costs and benefits of the different types of defenses and has been usefully extrapolated to their modes of deployment. Here we studied whether the herbivore-induced accumulation of JA, JA-Ile and ET changed over ontogeny in Nicotiana attenuata, a native tobacco in which inducible defenses are particularly well studied. Herbivore-elicited ET production changed dramatically during six developmental stages, from rosette through flowering, decreasing with the elongation of the first corollas during flower development. This decrease was largely recovered within a day after flower removal by decapitation. A similar pattern was found for the herbivore-induced accumulation of JA and JA-Ile. These results are consistent with ODT predictions and suggest that the last steps in floral development control the inducibility of at least three plant hormones, optimizing defense-growth tradeoffs.
Jones, Douglas L.; Johnson, Erik C.; Ratnam, Rama
A neural code based on sequences of spikes can consume a significant portion of the brain's energy budget. Thus, energy considerations would dictate that spiking activity be kept as low as possible. However, a high spike-rate improves the coding and representation of signals in spike trains, particularly in sensory systems. These are competing demands, and selective pressure has presumably worked to optimize coding by apportioning a minimum number of spikes so as to maximize coding fidelity. The mechanisms by which a neuron generates spikes while maintaining a fidelity criterion are not known. Here, we show that a signal-dependent neural threshold, similar to a dynamic or adapting threshold, optimizes the trade-off between spike generation (encoding) and fidelity (decoding). The threshold mimics a post-synaptic membrane (a low-pass filter) and serves as an internal decoder. Further, it sets the average firing rate (the energy constraint). The decoding process provides an internal copy of the coding error to the spike-generator which emits a spike when the error equals or exceeds a spike threshold. When optimized, the trade-off leads to a deterministic spike firing-rule that generates optimally timed spikes so as to maximize fidelity. The optimal coder is derived in closed-form in the limit of high spike-rates, when the signal can be approximated as a piece-wise constant signal. The predicted spike-times are close to those obtained experimentally in the primary electrosensory afferent neurons of weakly electric fish (Apteronotus leptorhynchus) and pyramidal neurons from the somatosensory cortex of the rat. We suggest that KCNQ/Kv7 channels (underlying the M-current) are good candidates for the decoder. They are widely coupled to metabolic processes and do not inactivate. We conclude that the neural threshold is optimized to generate an energy-efficient and high-fidelity neural code. PMID:26082710
Goel, R.; Kofman, I.; DeDios, Y. E.; Jeevarajan, J.; Stepanyan, V.; Nair, M.; Congdon, S.; Fregia, M.; Peters, B.; Cohen, H.; Wood, S.; Bloomberg, J. J.; Mulavara, A. P.
Sensorimotor changes such as postural and gait instabilities can affect the functional performance of astronauts when they transition across different gravity environments. We are developing a method, based on stochastic resonance (SR), to enhance information transfer by applying non-zero levels of external noise on the vestibular system (vestibular stochastic resonance, VSR). The goal of this project was to determine optimal levels of stimulation for SR applications by using a defined vestibular threshold of motion detection.
Saltykov, A B; Toloknov, A V; Khitrov, N K
The influence of the intensity of conditional stimulation on the speed of instrumental teaching of rats at different probabilities of casual fulfillment of the reaction under development (VSPR) was investigated. The VSPR value significantly affects the number of positive and negative confirmations in the early period of teaching and, finally, the informational individuum-environment interaction. Therefore, with the existing choice of VSPR values the dependence of the speed of teaching upon different unfavourable factors lessens, which may be used for optimization of the process of instrumental teaching at a low intensity of the conditional signal.
Stagner, Jessica P.; Laude, Jennifer R.; Zentall, Thomas R.
When pigeons are given a choice between two alternatives, one leading to a stimulus 20% of the time that always signals reinforcement (S+) or another stimulus 80% of the time that signals no reinforcement (S-), and the other alternative leading to one of two stimuli each signaling reinforcement 50% of the time, they show a strong preference for…
Ryad, Amdoun; Lakhdar, Khelifi; Majda, Khelifi-Slaoui; Samia, Amroune; Mark, Asch; Corinne, Assaf-Ducrocq; Eric, Gontier
Traditionally, optimization in biological analyses has been carried out by monitoring the influence of one factor at a time; this technique is called one-variable-at-a-time. The disadvantage of this technique is that it does not include any interactive effects among the variables studied and requires a large number of experiments. Therefore, in recent years, the Response Surface Methodology (RSM) has become the most popular optimization method. It is an effective mathematical and statistical technique which has been widely used in optimization studies with minimal experimental trials where interactive factors may be involved. This present study follows on from our previous work, where RSM was used to optimize the B5 medium composition in [NO(3-)], [Ca(2+)] and sucrose to attain the best production of hyoscyamine (HS) from the hairy roots (HRs) of Datura stramonium elicited by Jasmonic Acid (JA). The present paper focuses on the use of the RSM in biological studies, such as plant material, to establish a predictive model with the planning of experiments, analysis of the model, diagnostics and adjustment for the accuracy of the model. With the RSM, only 20 experiments were necessary to determine optimal concentrations. The model could be employed to carry out interpolations and predict the response to elicitation. Applying this model, the optimization of the HS level was 212.7% for the elicited HRs of Datura stramonium, cultured in B5-OP medium (optimized), in comparison with elicited HRs cultured in B5 medium (control). The optimal concentrations, under experimental conditions, were determined to be: 79.1 mM [NO(3-)], 11.4 mM [Ca(2+)] and 42.9 mg/L of sucrose.
Katz, Phyllis A.
The most significant finding is that stimulus-predifferentiation training elicited lower prejudice scores for children on two indices of ethnic attitudes than did a no-label control condition. (Author)
Zeyl, Timothy; Yin, Erwei; Keightley, Michelle; Chau, Tom
Objective. Error-related potentials (ErrPs) have the potential to guide classifier adaptation in BCI spellers, for addressing non-stationary performance as well as for online optimization of system parameters, by providing imperfect or partial labels. However, the usefulness of ErrP-based labels for BCI adaptation has not been established in comparison to other partially supervised methods. Our objective is to make this comparison by retraining a two-step P300 speller on a subset of confident online trials using naïve labels taken from speller output, where confidence is determined either by (i) ErrP scores, (ii) posterior target scores derived from the P300 potential, or (iii) a hybrid of these scores. We further wish to evaluate the ability of partially supervised adaptation and retraining methods to adjust to a new stimulus-onset asynchrony (SOA), a necessary step towards online SOA optimization. Approach. Eleven consenting able-bodied adults attended three online spelling sessions on separate days with feedback in which SOAs were set at 160 ms (sessions 1 and 2) and 80 ms (session 3). A post hoc offline analysis and a simulated online analysis were performed on sessions two and three to compare multiple adaptation methods. Area under the curve (AUC) and symbols spelled per minute (SPM) were the primary outcome measures. Main results. Retraining using supervised labels confirmed improvements of 0.9 percentage points (session 2, p < 0.01) and 1.9 percentage points (session 3, p < 0.05) in AUC using same-day training data over using data from a previous day, which supports classifier adaptation in general. Significance. Using posterior target score alone as a confidence measure resulted in the highest SPM of the partially supervised methods, indicating that ErrPs are not necessary to boost the performance of partially supervised adaptive classification. Partial supervision significantly improved SPM at a novel SOA, showing promise for eventual online SOA
Khameneh, Hanif Javanmard; Ho, Adrian W. S.; Spreafico, Roberto; Derks, Heidi; Quek, Hazel Q. Y.
Despite a long history and extensive usage of insoluble aluminum salts (alum) as vaccine adjuvants, the molecular mechanisms underpinning Ag-specific immunity upon vaccination remain unclear. Dendritic cells (DCs) are crucial initiators of immune responses, but little is known about the molecular pathways used by DCs to sense alum and, in turn, activate T and B cells. In this article, we show that alum adjuvanticity requires IL-2 specifically released by DCs, even when T cell secretion of IL-2 is intact. We demonstrate that alum, as well as other sterile particulates, such as uric acid crystals, induces DCs to produce IL-2 following initiation of actin-mediated phagocytosis that leads to Src and Syk kinase activation, Ca2+ mobilization, and calcineurin-dependent activation of NFAT, the master transcription factor regulating IL-2 expression. Using chimeric mice, we show that DC-derived IL-2 is required for maximal Ag-specific proliferation of CD4+ T cells and optimal humoral responses following alum-adjuvanted immunization. These data identify DC-derived IL-2 as a key mediator of alum adjuvanticity in vivo and the Src–Syk pathway as a potential leverage point in the rational design of novel adjuvants. PMID:27895176
Berquist, Michael D; Fantegrossi, William E
Numerous drugs elicit locomotor stimulant effects at appropriate doses; however, we typically reserve the term psychostimulant to refer to drugs with affinity for monoamine reuptake transporters. This chapter comprises select experiments that have characterized the discriminative stimulus effects of psychostimulants using drug discrimination procedures. The substitution profiles of psychostimulants in laboratory rodents are generally consistent with those observed in human and nonhuman primate drug discrimination experiments. Notably, two major classes of psychostimulants can be distinguished as those that function as passive monoamine reuptake inhibitors (such as cocaine) and those that function as substrates for monoamine transporters and stimulate monoamine release (such as the amphetamines). Nevertheless, the discriminative stimulus effects of both classes of psychostimulant are quite similar, and drugs from different classes will substitute for one another. Most importantly, for both the cocaine-like and amphetamine-like psychostimulants, dopaminergic mechanisms most saliently determine discriminative stimulus effects, but these effects can be modulated by alterations in noradrenergic and serotonergic neurotransmission as well. Thusly, the drug discrimination assay is useful for characterizing the interoceptive effects of psychostimulants and determining the mechanisms that contribute to their subjective effects in humans.
Puce, Aina; McNeely, Marie E.; Berrebi, Michael E.; Thompson, James C.; Hardee, Jillian; Brefczynski-Lewis, Julie
How do our brains respond when we are being watched by a group of people?Despite the large volume of literature devoted to face processing, this question has received very little attention. Here we measured the effects on the face-sensitive N170 and other ERPs to viewing displays of one, two and three faces in two experiments. In Experiment 1, overall image brightness and contrast were adjusted to be constant, whereas in Experiment 2 local contrast and brightness of individual faces were not manipulated. A robust positive-negative-positive (P100-N170-P250) ERP complex and an additional late positive ERP, the P400, were elicited to all stimulus types. As the number of faces in the display increased, N170 amplitude increased for both stimulus sets, and latency increased in Experiment 2. P100 latency and P250 amplitude were affected by changes in overall brightness and contrast, but not by the number of faces in the display per se. In Experiment 1 when overall brightness and contrast were adjusted to be constant, later ERP (P250 and P400) latencies showed differences as a function of hemisphere. Hence, our data indicate that N170 increases its magnitude when multiple faces are seen, apparently impervious to basic low-level stimulus features including stimulus size. Outstanding questions remain regarding category-sensitive neural activity that is elicited to viewing multiple items of stimulus categories other than faces. PMID:23785327
Faced with their first reporting deadlines for economic-stimulus aid to education, school districts are toiling over how every stimulus penny has been spent so far and how many jobs have been saved--numbers that will be scrutinized not just by the public, but by government auditors as well. The American Recovery and Reinvestment Act, passed by…
White, Rebekah C; Plassart, Anna
In stimulus-parity synaesthesia, a range of stimuli-for example, letters, numbers, weekdays, months, and colours (the inducers)-elicit an automatic feeling of oddness or evenness (the concurrent). This phenomenon was first described by Théodore Flournoy in 1893, and has only recently been "rediscovered." Here, we describe an individual who experiences a comparable phenomenon, but uses the labels negative and positive rather than odd and even. Stimulus-parity synaesthesia may be broader than first supposed, and it is important that assessments are sensitive to this breadth.
Bang, Sun Jung; Allen, Timothy A; Jones, Lauren K; Boguszewski, Pawel; Brown, Thomas H
Rodent ultrasonic vocalizations (USVs) are ethologically critical social signals. Rats emit 22kHz USVs and 50kHz USVs, respectively, in conjunction with negative and positive affective states. Little is known about what controls emotional reactivity to these social signals. Using male Sprague-Dawley rats, we examined unconditional and conditional freezing behavior in response to the following auditory stimuli: three 22kHz USVs, a discontinuous tone whose frequency and on-off pattern matched one of the USVs, a continuous tone with the same or lower frequencies, a 4kHz discontinuous tone with an on-off pattern matched to one of the USVs, and a 50kHz USV. There were no differences among these stimuli in terms of the unconditional elicitation of freezing behavior. Thus, the stimuli were equally neutral before conditioning. During differential fear conditioning, one of these stimuli (the CS(+)) always co-terminated with a footshock unconditional stimulus (US) and another stimulus (the CS(-)) was explicitly unpaired with the US. There were no significant differences among these cues in CS(+)-elicited freezing behavior. Thus, the stimuli were equally salient or effective as cues in supporting fear conditioning. When the CS(+) was a 22kHz USV or a similar stimulus, rats discriminated based on the principal frequency and/or the temporal pattern of the stimulus. However, when these same stimuli served as the CS(-), discrimination failed due to generalization from the CS(+). Thus, the stimuli differed markedly in the specificity of conditioning. This strikingly asymmetrical stimulus generalization is a novel bias in discrimination.
Cairns, Darren Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)
Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.
Cairns, Darran Robert (Inventor); Huebsch, Wade W. (Inventor); Sierros, Konstantinos A. (Inventor); Shafran, Matthew S. (Inventor)
Disclosed are various embodiments of methods and systems related to stimulus responsive nanoparticles. In one embodiment includes a stimulus responsive nanoparticle system, the system includes a first electrode, a second electrode, and a plurality of elongated electro-responsive nanoparticles dispersed between the first and second electrodes, the plurality of electro-responsive nanorods configured to respond to an electric field established between the first and second electrodes.
Knowledge elicitation from human beings is important for many fields, such as decision support systems, risk communication, and customer preference studying. Traditional approaches include observations, questionnaires, structured and semi-structured interviews, and group discussions. Many publications have been studying different techniques for a…
Crago, Patrick E; Makowski, Nathan S
Objective Stimulation of peripheral nerves is often superimposed on ongoing motor and sensory activity in the same axons, without a quantitative model of the net action potential train at the axon endpoint. Approach We develop a model of action potential patterns elicited by superimposing constant frequency axonal stimulation on the action potentials arriving from a physiologically activated neural source. The model includes interactions due to collision block, resetting of the neural impulse generator, and the refractory period of the axon at the point of stimulation. Main Results Both the mean endpoint firing rate and the probability distribution of the action potential firing periods depend strongly on the relative firing rates of the two sources and the intersite conduction time between them. When the stimulus rate exceeds the neural rate, neural action potentials do not reach the endpoint and the rate of endpoint action potentials is the same as the stimulus rate, regardless of the intersite conduction time. However, when the stimulus rate is less than the neural rate, and the intersite conduction time is short, the two rates partially sum. Increases in stimulus rate produce non-monotonic increases in endpoint rate and continuously increasing block of neurally generated action potentials. Rate summation is reduced and more neural action potentials are blocked as the intersite conduction time increases.. At long intersite conduction times, the endpoint rate simplifies to being the maximum of either the neural or the stimulus rate. Significance This study highlights the potential of increasing the endpoint action potential rate and preserving neural information transmission by low rate stimulation with short intersite conduction times. Intersite conduction times can be decreased with proximal stimulation sites for muscles and distal stimulation sites for sensory endings. The model provides a basis for optimizing experiments and designing neuroprosthetic
Crago, Patrick E.; Makowski, Nathaniel S.
Objective. Stimulation of peripheral nerves is often superimposed on ongoing motor and sensory activity in the same axons, without a quantitative model of the net action potential train at the axon endpoint. Approach. We develop a model of action potential patterns elicited by superimposing constant frequency axonal stimulation on the action potentials arriving from a physiologically activated neural source. The model includes interactions due to collision block, resetting of the neural impulse generator, and the refractory period of the axon at the point of stimulation. Main results. Both the mean endpoint firing rate and the probability distribution of the action potential firing periods depend strongly on the relative firing rates of the two sources and the intersite conduction time between them. When the stimulus rate exceeds the neural rate, neural action potentials do not reach the endpoint and the rate of endpoint action potentials is the same as the stimulus rate, regardless of the intersite conduction time. However, when the stimulus rate is less than the neural rate, and the intersite conduction time is short, the two rates partially sum. Increases in stimulus rate produce non-monotonic increases in endpoint rate and continuously increasing block of neurally generated action potentials. Rate summation is reduced and more neural action potentials are blocked as the intersite conduction time increases. At long intersite conduction times, the endpoint rate simplifies to being the maximum of either the neural or the stimulus rate. Significance. This study highlights the potential of increasing the endpoint action potential rate and preserving neural information transmission by low rate stimulation with short intersite conduction times. Intersite conduction times can be decreased with proximal stimulation sites for muscles and distal stimulation sites for sensory endings. The model provides a basis for optimizing experiments and designing neuroprosthetic
The topic of stimulus control is too broad and complex to be traceable here. It would probably take a two-semester course to cover just the highlights of that field's evolution. The more restricted topic of equivalence relations has itself become so broad that even an introductory summary requires more time than we have available. An examination…
Kish, George B.; Donnenwerth, Gregory V.
Examines relationships between Sensation-Seeking Scale (SSS) and vocational interests measured by the Kuder and Strong Vocational Interest Blank, among alcoholics and undergraduates. Results support construct validity of the SSS and provide further evidence of modes of expression of stimulus-seeking needs in personality. (Author/CJ)
Zhang, Zhubo D.; Chacron, Maurice J.
Understanding the coding strategies used to process sensory input remains a central problem in neuroscience. Growing evidence suggests that sensory systems process natural stimuli efficiently by ensuring a close match between neural tuning and stimulus statistics through adaptation. However, adaptation causes ambiguity as the same response can be elicited by different stimuli. The mechanisms by which the brain resolves ambiguity remain poorly understood. Here we investigated adaptation in electrosensory pyramidal neurons within different parallel maps in the weakly electric fish Apteronotus leptorhynchus. In response to step increases in stimulus variance, we found that pyramidal neurons within the lateral segment (LS) displayed strong scale invariant adaptation whereas those within the centromedial segment (CMS) instead displayed weaker degrees of scale invariant adaptation. Signal detection analysis revealed that strong adaptation in LS neurons significantly reduced stimulus discriminability. In contrast, weaker adaptation displayed by CMS neurons led to significantly lesser impairment of discriminability. Thus, while LS neurons display adaptation that is matched to natural scene statistics, thereby optimizing information transmission, CMS neurons instead display weaker adaptation and would instead provide information about the context in which these statistics occur. We propose that such a scheme is necessary for decoding by higher brain structures. PMID:27349635
Zhang, Zhubo D; Chacron, Maurice J
Understanding the coding strategies used to process sensory input remains a central problem in neuroscience. Growing evidence suggests that sensory systems process natural stimuli efficiently by ensuring a close match between neural tuning and stimulus statistics through adaptation. However, adaptation causes ambiguity as the same response can be elicited by different stimuli. The mechanisms by which the brain resolves ambiguity remain poorly understood. Here we investigated adaptation in electrosensory pyramidal neurons within different parallel maps in the weakly electric fish Apteronotus leptorhynchus. In response to step increases in stimulus variance, we found that pyramidal neurons within the lateral segment (LS) displayed strong scale invariant adaptation whereas those within the centromedial segment (CMS) instead displayed weaker degrees of scale invariant adaptation. Signal detection analysis revealed that strong adaptation in LS neurons significantly reduced stimulus discriminability. In contrast, weaker adaptation displayed by CMS neurons led to significantly lesser impairment of discriminability. Thus, while LS neurons display adaptation that is matched to natural scene statistics, thereby optimizing information transmission, CMS neurons instead display weaker adaptation and would instead provide information about the context in which these statistics occur. We propose that such a scheme is necessary for decoding by higher brain structures.
Mezue, Melvin; Segerdahl, Andrew R; Okell, Thomas W; Chappell, Michael A; Kelly, Michael E; Tracey, Irene
Arterial spin labeling (ASL) sequences that incorporate multiple postlabeling delay (PLD) times allow estimation of when arterial blood signal arrives within a region of interest. Sequences that account for such variability may improve the reliability of ASL and therefore make the technique well suited for future clinical and experimental investigations of cerebral perfusion. This study assessed the within- and between-session reproducibility of an optimized pseudo-continuous ASL (pCASL) functional magnetic resonance imaging (FMRI) sequence that incorporates multiple postlabeling delays (multi-PLD pCASL). Healthy subjects underwent four identical scans separated by 30 minutes, 1 week, and 1 month using multi-PLD pCASL to image absolute perfusion (cerebral blood flow (CBF) and arterial arrival time (AAT)) during both rest and a visual-cued motor task. We show good test-retest reliability, with strong consistency across subjects and sessions during rest (inter-session within-subject coefficient of variation: gray matter (GM) CBF=6.44% GM AAT=2.20%). We also report high sensitivity and reproducibility during the functional task, where we show robust task-related decreases in AAT corresponding with regions of increased CBF. Importantly, these results give insight into optimal PLD selection for future investigations using single-PLD ASL to image different brain regions, and highlight the necessity of multi-PLD ASL when imaging perfusion in the whole brain. PMID:25269517
The main problem with sensory processing is the difficulty in relating sensory input to physiological responses and perception. This is especially problematic at higher levels of processing, where complex cues elicit highly specific responses. In olfaction, this relationship is particularly obfuscated by the difficulty of characterizing stimulus statistics and perception. The core questions in olfaction are hence the so-called stimulus problem, which refers to the understanding of the stimulus, and the structure-activity and structure-odor relationships, which refer to the molecular basis of smell. It is widely accepted that the recognition of odorants by receptors is governed by the detection of physico-chemical properties and that the physical space is highly complex. Not surprisingly, ideas differ about how odor stimuli should be classified and about the very nature of information that the brain extracts from odors. Even though there are many measures for smell, there is none that accurately describes all aspects of it. Here, we summarize recent developments in the understanding of olfaction. We argue that an approach to olfactory function where information processing is emphasized could contribute to a high degree to our understanding of smell as a perceptual phenomenon emerging from neural computations. Further, we argue that combined analysis of the stimulus, biology, physiology, and behavior and perception can provide new insights into olfactory function. We hope that the reader can use this review as a competent guide and overview of research activities in olfactory physiology, psychophysics, computation, and psychology. We propose avenues for research, particularly in the systematic characterization of receptive fields and of perception.
Colombo, J; Mitchell, D W; Coldren, J T; Atwater, J D
In four studies, 3-, 6-, and 9-month-old human infants were tested in a discrimination learning task in which visual fixation to a particular stimulus or lateral position was reinforced with an auditory stimulus. In Experiment 1, all age groups exhibited acquisition, extinction, and reinstatement of fixation to the reinforced target or position. Experiment 2 revealed that 3-month-olds retained the positional discrimination but not the stimulus discrimination after a 5-min delay between acquisition and extinction; older infants retained both types of discriminations. In Experiments 3 and 4 we investigated a possible developmental shift in the dominance of positional versus stimulus cues by training infants on displays in which stimulus and position were confounded and then by dissociating the cues on test trials. Results from both experiments indicated positional cue dominance for young infants and stimulus cue dominance for older infants. The findings are discussed in terms of differences in the attentional demands elicited by proprioceptive versus exteroceptive cues.
systems approach: characterized by Checkland’s Soft Systems Methodology (SSM), which is discussed briefly in Appendix A.6; emphasizes the subjectivity of...methodology for requirements elicitation. A.6 Notes on SSM Both the definition of methodology and the philosophy behind soft systems methodology (SSM...1986. [Checkland 89a] Checkland, Peter. Soft Systems Methodology . Rational Analysis for a Problematic World. New York: John Wiley & Sons, 71-100
Fu, Yuan-hui; Jiao, Yue-Ying; He, Jin-sheng; Giang, Gui-Yuan; Zhang, Wei; Yan, Yi-Fei; Ma, Yao; Hua, Ying; Zhang, Ying; Peng, Xiang-Lei; Shi, Chang-Xin; Hong, Tao
Sublingual (s.l.) immunization has been described as a convenient and safe way to induce mucosal immune responses in the respiratory and genital tracts. We constructed a helper-dependent adenoviral (HDAd) vector expressing a condon-optimized soluble fusion glycoprotein (sFsyn) of respiratory syncytial virus (HDAd-sFsyn) and explored the potential of s.l. immunization with HDAd-sFsyn to stimulate immune responses in the respiratory mucosa. The RSV specific systemic and mucosal immune responses were generated in BALB/c mice, and the serum IgG with neutralizing activity was significantly elevated after homologous boost with s.l. application of HDAd-sFsyn. Humoral immune responses could be measured even 14weeks after a single immunization. Upon challenge, s.l. immunization with HDAd-sFsyn displayed an effective protection against RSV infection. These findings suggest that s.l. administration of HDAd-sFsyn acts as an effective and safe mucosal vaccine against RSV infection, and may be a useful tool in the prevention of RSV infection.
Ladu, Fabrizio; Bartolini, Tiziana; Panitz, Sarah G.; Butail, Sachit; Macrı, Simone; Porfiri, Maurizio
We investigate the behavioral response of zebrafish to three fear-evoking stimuli. In a binary choice test, zebrafish are exposed to a live allopatric predator, a biologically-inspired robot, and a computer-animated image of the live predator. A target tracking algorithm is developed to score zebrafish behavior. Unlike computer-animated images, the robotic and live predator elicit a robust avoidance response. Importantly, the robotic stimulus elicits more consistent inter-individual responses than the live predator. Results from this effort are expected to aid in hypothesis-driven studies on zebrafish fear response, by offering a valuable approach to maximize data-throughput and minimize animal subjects.
Hulme, Oliver J.; Friston, Karl F.; Zeki, Semir
Most experiments on the “neural correlates of consciousness” employ stimulus reportability as an operational definition of what is consciously perceived. The interpretation of such experiments therefore depends critically on understanding the neural basis of stimulus reportability. Using a high volume of fMRI data, we investigated the neural correlates of stimulus reportability using a partial report object detection paradigm. Subjects were presented with a random array of circularly arranged disc-stimuli and were cued, after variable delays (following stimulus offset), to report the presence or absence of a disc at the cued location, using variable motor actions. By uncoupling stimulus processing, decision, and motor response, we were able to use signal detection theory to deconstruct the neural basis of stimulus reportability. We show that retinotopically specific responses in the early visual cortex correlate with stimulus processing but not decision or report; a network of parietal/temporal regions correlates with decisions but not stimulus presence, whereas classical motor regions correlate with report. These findings provide a basic framework for understanding the neural basis of stimulus reportability without the theoretical burden of presupposing a relationship between reportability and consciousness. PMID:18823251
Wang, Chin-An; Munoz, Douglas P
The sudden appearance of a novel stimulus initiates a series of responses to orient the body for appropriate actions, including not only shifts of gaze and attention, but also transient pupil dilation. Modulation of pupil dynamics by stimulus properties is less understood, although its effects on other components of orienting have been extensively explored. Microstimulation of the superior colliculus evoked transient pupil dilation, and the initial component of pupil dilation evoked by microstimulation was similar to that elicited by the presentation of salient sensory stimuli, suggesting a coordinated role of the superior colliculus on this behavior, although evidence in humans is yet to be established. To examine pupil orienting responses in humans, we presented visual stimuli while participants fixated on a central visual spot. Transient pupil dilation in humans was elicited after presentation of a visual stimulus in the periphery. The evoked pupil responses were modulated systematically by stimulus contrast, with faster and larger pupil responses triggered by higher contrast stimuli. The pupil response onset latencies for high contrast stimuli were similar to those produced by the light reflex and significantly faster than the darkness reflex, suggesting that the initial component of pupil dilation is probably mediated by inhibition of the parasympathetic pathway. The contrast modulation was pronounced under different levels of baseline pupil size. Together, our results demonstrate visual contrast modulation on the orienting pupil response in humans.
Sigurdardottir, Zuilma Gabriela; Mackay, Harry A.; Green, Gina
Stimulus generalization and contextual control affect the development of equivalence classes. Experiment 1 demonstrated primary stimulus generalization from the members of trained equivalence classes. Adults were taught to match six spoken Icelandic nouns and corresponding printed words and pictures to one another in computerized three-choice…
Pimenta, Dióghenes; Tonneau, François
Human subjects were exposed to AB, AC stimulus pairs and then to matching-to-sample tests of stimulus equivalence (B-A, C-A, B-C, C-B) or to a task in which stimulus compounds (BA, CA, BC, CB) were rated for attractiveness. Matching-to-sample tests revealed emergent B-A, C-A, B-C, and C-B choices, replicating previous results in the literature. The mean proportion of correct, emergent choices increased as a function of exposure to the AB, AC pairs. On the rating task, the liking scores of all stimulus compounds also increased as a function of exposure to the AB, AC pairs. After limited exposure to these pairs, however, the liking scores of the BC and CB compounds were negative. These findings are discussed in relation to perceptual and associative perspectives on the behavioral effects of stimulus correlations.
Williams, B A
Interest in operant research on stimulus control has declined at the same time that much interest has burgeoned in nonoperant areas. Several examples of this shift toward traditional learning theory are considered, all of which have sponsored theoretical approaches that attempt to characterize the underlying associative units. These theoretical approaches are defended on the grounds that they have generated a deeper understanding of a variety of often puzzling phenomena. My projection is that future research will be determined even more strongly by theories about the structure of associations. Particular issues for which such discussion will have major impact include (1) whether conditional stimulus control is qualitatively different than simpler forms of stimulus control, (2) whether stimulus control is organized hierarchically, and (3) the origin of categories of stimulus equivalence. PMID:6520579
John, Sam E.; Shivdasani, Mohit N.; Williams, Chris E.; Morley, John W.; Shepherd, Robert K.; Rathbone, Graeme D.; Fallon, James B.
Objective. Neural responses to biphasic constant current pulses depend on stimulus pulse parameters such as polarity, duration, amplitude and interphase gap. The objective of this study was to systematically evaluate and optimize stimulus pulse parameters for a suprachoroidal retinal prosthesis. Approach. Normally sighted cats were acutely implanted with platinum electrode arrays in the suprachoroidal space. Monopolar stimulation comprised of monophasic and biphasic constant current pulses with varying polarity, pulse duration and interphase gap. Multiunit responses to electrical stimulation were recorded in the visual cortex. Main results. Anodal stimulation elicited cortical responses with shorter latencies and required lower charge per phase than cathodal stimulation. Clinically relevant retinal stimulation required relatively larger charge per phase compared with other neural prostheses. Increasing the interphase gap of biphasic pulses reduced the threshold of activation; however, the benefits of using an interphase gap need to be considered in light of the pulse duration and polarity used and other stimulation constraints. Based on our results, anodal first biphasic pulses between 300-1200 µs are recommended for suprachoroidal retinal stimulation. Significance. These results provide insights into the efficacy of different pulse parameters for suprachoroidal retinal stimulation and have implications for the design of safe and clinically relevant stimulators for retinal prostheses.
Geran, Laura; Travers, Susan
It has been demonstrated that temporal features of spike trains can increase the amount of information available for gustatory processing. However, the nature of these temporal characteristics and their relationship to different taste qualities and neuron types are not well-defined. The present study analyzed the time course of taste responses from parabrachial (PBN) neurons elicited by multiple applications of "sweet" (sucrose), "salty" (NaCl), "sour" (citric acid), and "bitter" (quinine and cycloheximide) stimuli in an acute preparation. Time course varied significantly by taste stimulus and best-stimulus classification. Across neurons, the ensemble code for the three electrolytes was similar initially but quinine diverged from NaCl and acid during the second 500 ms of stimulation and all four qualities became distinct just after 1s. This temporal evolution was reflected in significantly broader tuning during the initial response. Metric space analyses of quality discrimination by individual neurons showed that increases in information (H) afforded by temporal factors was usually explained by differences in rate envelope, which had a greater impact during the initial 2s (22.5% increase in H) compared to the later response (9.5%). Moreover, timing had a differential impact according to cell type, with between-quality discrimination in neurons activated maximally by NaCl or citric acid most affected. Timing was also found to dramatically improve within-quality discrimination (80% increase in H) in neurons that responded optimally to bitter stimuli (B-best). Spikes from B-best neurons were also more likely to occur in bursts. These findings suggest that among PBN taste neurons, time-dependent increases in mutual information can arise from stimulus- and neuron-specific differences in response envelope during the initial dynamic period. A stable rate code predominates in later epochs.
Perkins, Kenneth A
Behavioral discrimination procedures clearly demonstrate that nicotine elicits interoceptive stimulus effects in humans that are malleable by various pharmacological manipulations as well as by some behavioral manipulations. The parameters of nicotine discrimination and both chronic and acute factors that may alter discrimination behavior are addressed in this chapter, which emphasizes research by the author involving nicotine delivered by nasal spray. Human discrimination of nicotine is centrally mediated, as the central and peripheral nicotine antagonist mecamylamine blocks discrimination but the peripheral antagonist trimethaphan does not. The threshold dose for discrimination of nicotine via spray appears to be very low in smokers as well as nonsmokers. Because smoked tobacco delivers nicotine more rapidly than spray, the threshold dose of nicotine via smoking is probably even lower. In terms of individual differences, smokers may become tolerant to the discriminative stimulus effects of higher nicotine doses but not of low doses. Men may be more sensitive than women to nicotine's discriminative stimulus effects, consistent with other research suggesting that nicotine is more reinforcing in men than in women. Other potential individual differences in nicotine discrimination have not been clearly tested, but may include genetics, obesity, and dependence on other drugs. Acute environmental factors that alter nicotine discrimination include the specific training and testing conditions, pointing to the need for careful control over such conditions during research. Other factors, such as concurrent acute use of alcohol or caffeine, do not appear to alter nicotine discrimination, suggesting that changes in nicotine discrimination are not likely explanations for the association of smoking behavior with use of those drugs. Concurrent physical activity also does not appear to alter nicotine discrimination, indicating that results from studies of discrimination in
Runquist, Willard N.
The general purpose of this experiment was to determine whether differences in stimulus discrimination, as determined by the MIR (missing-item recognition) test, are correlated with interference in recall, as demanded by the discriminative coding hypothesis. (Author/RK)
Di Stefano, G.; Stubbs, M. T.; Djeugam, B.; Liang, M.
Abstract Feature selection has been extensively studied in the context of goal-directed behavior, where it is heavily driven by top-down factors. A more primitive version of this function is the detection of bottom-up changes in stimulus features in the environment. Indeed, the nervous system is tuned to detect fast-rising, intense stimuli that are likely to reflect threats, such as nociceptive somatosensory stimuli. These stimuli elicit large brain potentials maximal at the scalp vertex. When elicited by nociceptive laser stimuli, these responses are labeled laser-evoked potentials (LEPs). Although it has been shown that changes in stimulus modality and increases in stimulus intensity evoke large LEPs, it has yet to be determined whether stimulus displacements affect the amplitude of the main LEP waves (N1, N2, and P2). Here, in three experiments, we identified a set of rules that the human nervous system obeys to identify changes in the spatial location of a nociceptive stimulus. We showed that the N2 wave is sensitive to: (1) large displacements between consecutive stimuli in egocentric, but not somatotopic coordinates; and (2) displacements that entail a behaviorally relevant change in the stimulus location. These findings indicate that nociceptive-evoked vertex potentials are sensitive to behaviorally relevant changes in the location of a nociceptive stimulus with respect to the body, and that the hand is a particularly behaviorally important site. PMID:27419217
Goodman, Shawn S; Keefe, Douglas H
Otoacoustic emissions serve as a noninvasive probe of the medial olivocochlear (MOC) reflex. Stimulus frequency otoacoustic emissions (SFOAEs) elicited by a low-level probe tone may be the optimal type of emission for studying MOC effects because at low levels, the probe itself does not elicit the MOC reflex [Guinan et al. (2003) J. Assoc. Res. Otolaryngol. 4:521]. Based on anatomical considerations, the MOC reflex activated by ipsilateral acoustic stimulation (mediated by the crossed olivocochlear bundle) is predicted to be stronger than the reflex to contralateral stimulation. Broadband noise is an effective activator of the MOC reflex; however, it is also an effective activator of the middle-ear muscle (MEM) reflex, which can make results difficult to interpret. The MEM reflex may be activated at lower levels than measured clinically, and most previous human studies have not explicitly included measurements to rule out MEM reflex contamination. The current study addressed these issues using a higher-frequency SFOAE probe tone to test for cochlear changes mediated by the MOC reflex, while simultaneously monitoring the MEM reflex using a low-frequency probe tone. Broadband notched noise was presented ipsilaterally at various levels to elicit probe-tone shifts. Measurements are reported for 15 normal-hearing subjects. With the higher-frequency probe near 1.5 kHz, only 20% of subjects showed shifts consistent with an MOC reflex in the absence of an MEM-induced shift. With the higher-frequency probe near 3.5 kHz, up to 40% of subjects showed shifts in the absence of an MEM-induced shift. However, these responses had longer time courses than expected for MOC-induced shifts, and may have been dominated by other cochlear processes, rather than MOC reflex. These results suggest caution in the interpretation of effects observed using ipsilaterally presented acoustic activators intended to excite the MOC reflex.
Sigurðardóttir, Zuilma Gabriela; Mackay, Harry A; Green, Gina
Stimulus generalization and contextual control affect the development of equivalence classes. Experiment 1 demonstrated primary stimulus generalization from the members of trained equivalence classes. Adults were taught to match six spoken Icelandic nouns and corresponding printed words and pictures to one another in computerized three-choice matching-to-sample tasks. Tests confirmed that six equivalence classes had formed. Without further training, plural forms of the stimuli were presented in tests for all matching performances. All participants demonstrated virtually errorless performances. In Experiment 2, classifications of the nouns used in Experiment 1 were brought under contextual control. Three nouns were feminine and three were masculine. The match-to-sample training taught participants to select a comparison of the same number as the sample (i.e., singular or plural) in the presence of contextual stimulus A regardless of noun gender. Concurrently, in the presence of contextual stimulus B, participants were taught to select a comparison of the same gender as the sample (i.e., feminine or masculine), regardless of number. Generalization was assessed using a card-sorting test. All participants eventually sorted the cards correctly into gender and number stimulus classes. When printed words used in training were replaced by their picture equivalents, participants demonstrated almost errorless performances. PMID:22754102
Meier, Matt E.; Kane, Michael J.
Three experiments examined the relation between working memory capacity (WMC) and 2 different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (S-R) interference. Our goal was to test whether WMC's relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict),…
Wendt, Mike; Kluwe, Rainer H.; Peters, Alexandra
Compatibility level repetition benefits in interference paradigms have been taken to reflect enhanced processing selectivity in response to cognitive conflict elicited by a task-irrelevant stimulus feature. The authors demonstrate such sequential effects in the Simon task which (a) occur independent of previous behavioral conflict effects and (b)…
Fukutomi, Matasaburo; Someya, Makoto; Ogawa, Hiroto
Animals flexibly change their locomotion triggered by an identical stimulus depending on the environmental context and behavioral state. This indicates that additional sensory inputs in different modality from the stimulus triggering the escape response affect the neuronal circuit governing that behavior. However, how the spatio-temporal relationships between these two stimuli effect a behavioral change remains unknown. We studied this question, using crickets, which respond to a short air-puff by oriented walking activity mediated by the cercal sensory system. In addition, an acoustic stimulus, such as conspecific 'song' received by the tympanal organ, elicits a distinct oriented locomotion termed phonotaxis. In this study, we examined the cross-modal effects on wind-elicited walking when an acoustic stimulus was preceded by an air-puff and tested whether the auditory modulation depends on the coincidence of the direction of both stimuli. A preceding 10 kHz pure tone biased the wind-elicited walking in a backward direction and elevated a threshold of the wind-elicited response, whereas other movement parameters, including turn angle, reaction time, walking speed and distance were unaffected. The auditory modulations, however, did not depend on the coincidence of the stimulus directions. A preceding sound consistently altered the wind-elicited walking direction and response probability throughout the experimental sessions, meaning that the auditory modulation did not result from previous experience or associative learning. These results suggest that the cricket nervous system is able to integrate auditory and air-puff stimuli, and modulate the wind-elicited escape behavior depending on the acoustic context.
Zentall, Sydney S.
Twenty-two hyperactive children were more spontaneously talkative than controls during transitions and nonverbal tasks (nonelicited conditions), but less talkative when asked to tell stories (elicited conditions). Findings suggest that minimal stimulus input precipitate excessive verbal activity from hyperactive children, while stories requiring…
The eminent psychophysicist, S. S. Stevens, once remarked that, “the basic problem of psychology was the definition of the stimulus” (Stevens, 1951, p. 46). By expanding the traditional definition of the stimulus, the study of animal learning has metamorphosed into animal cognition. The main impetus for that change was the recognition that it is often necessary to postulate a representation between the traditional S and R of learning theory. Representations allow a subject to re-present a stimulus it learned previously that is currently absent. Thus, in delayed-matching-to-sample, one has to assume that a subject responds to a representation of the sample during test if it responds correctly. Other examples, to name but a few, include concept formation, spatial memory, serial memory, learning a numerical rule, imitation and metacognition. Whereas a representation used to be regarded as a mentalistic phenomenon that was unworthy of scientific inquiry, it can now be operationally defined. To accommodate representations, the traditional discriminative stimulus has to be expanded to allow for the role of representations. The resulting composite can account for a significantly larger portion of the variance of performance measures than the exteroceptive stimulus could by itself. PMID:19969047
Davison, Michael; Baum, William M.
Four pigeons were trained in a procedure in which concurrent-schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green-key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight…
Hietanen, Jonne O; Hietanen, Jari K
The effect of eye contact on self-awareness was investigated with implicit measures based on the use of first-person singular pronouns in sentences. The measures were proposed to tap into self-referential processing, that is, information processing associated with self-awareness. In addition, participants filled in a questionnaire measuring explicit self-awareness. In Experiment 1, the stimulus was a video clip showing another person and, in Experiment 2, the stimulus was a live person. In both experiments, participants were divided into two groups and presented with the stimulus person either making eye contact or gazing downward, depending on the group assignment. During the task, the gaze stimulus was presented before each trial of the pronoun-selection task. Eye contact was found to increase the use of first-person pronouns, but only when participants were facing a real person, not when they were looking at a video of a person. No difference in self-reported self-awareness was found between the two gaze direction groups in either experiment. The results indicate that eye contact elicits self-referential processing, but the effect may be stronger, or possibly limited to, live interaction.
Green, David B.; Ohlemacher, Jocelyn; Rosen, Merri J.
Perceptual learning (training-induced performance improvement) can be elicited by task-irrelevant stimulus exposure in humans. In contrast, task-irrelevant stimulus exposure in animals typically disrupts perception in juveniles while causing little to no effect in adults. This may be due to the extent of exposure, which is brief in humans while chronic in animals. Here we assessed the effects of short bouts of passive stimulus exposure on learning during development in gerbils, compared with non-passive stimulus exposure (i.e., during testing). We used prepulse inhibition of the acoustic startle response, a method that can be applied at any age, to measure gap detection thresholds across four age groups, spanning development. First, we showed that both gap detection thresholds and gap detection learning across sessions displayed a long developmental trajectory, improving throughout the juvenile period. Additionally, we demonstrated larger within- and across-animal performance variability in younger animals. These results are generally consistent with results in humans, where there are extended developmental trajectories for both the perception of temporally-varying signals, and the effects of perceptual training, as well as increased variability and poorer performance consistency in children. We then chose an age (mid-juveniles) that displayed clear learning over sessions in order to assess effects of brief passive stimulus exposure on this learning. We compared learning in mid-juveniles exposed to either gap detection testing (gaps paired with startles) or equivalent gap exposure without testing (gaps alone) for three sessions. Learning was equivalent in both these groups and better than both naïve age-matched animals and controls receiving no gap exposure but only startle testing. Thus, short bouts of exposure to gaps independent of task performance is sufficient to induce learning at this age, and is as effective as gap detection testing. PMID:27378837
Van Gucht, Dinska; Vansteenwegen, Debora; Van den Bergh, Omer; Beckers, Tom
In two experiments, we used a Pavlovian differential conditioning procedure to induce craving for chocolate. As a result of repeated pairing with chocolate intake, initially neutral cues came to elicit an automatic approach tendency in a speeded stimulus-response compatibility reaction time task. This automatic approach tendency, moreover, seemed to be sensitive to manipulations of extinction and renewal in the Pavlovian conditioning procedure. These findings corroborate and extend previous reports of automatic approach tendencies elicited by substance-relevant cues in addiction, while controlling for alternative accounts for such observations. Moreover, our data lend support to and extend learning models of cue-induced craving and addiction. Finally, we argue that the procedure we present here provides an ecologically valid behavioural tool that allows studying processes involved in cue-induced craving, addiction and relapse without relying on verbal report.
Young, B J; Leaton, R N
Amygdala central nucleus (CNA) lesions were used to test the hypothesis that stimulus-evoked heart rate changes can reflect the development of fear during acoustic startle testing. A 120-dB white noise startle stimulus produced freezing as well as phasic heart rate accelerations and decelerations, and an abrupt decrease in tonic heart rate, in sham-operated rats. These responses were all significantly reduced in CNA-lesioned rats. In contrast, an 87-dB stimulus elicited only significant phasic decelerations that were similarly attenuated by the CNA lesions. In a follow-up experiment, the CNA lesions also attenuated phasic cardiac decelerations evoked by a conditioned stimulus-like, 85-dB pure tone. The results support the contention (B. J. Young & R.N. Leaton, 1994) that heart rate changes can reflect fear conditioned during acoustic startle testing and, in addition, suggest that the amygdala mediates responses to nonsignal acoustic stimuli.
Gobbo, M; Gaffurini, P; Bissolotti, L; Esposito, F; Orizio, C
The aim of the study was to investigate the influence of two different transcutaneous neuromuscular electrical stimulation procedures on evoked muscle torque and local tissue oxygenation. In the first one (MP mode), the cathode was facing the muscle main motor point and stimulus amplitude was set to the level eliciting the maximal myoelectrical activation according to the amplitude of the evoked electromyogram (EMG); in the second one (RC mode), the electrodes were positioned following common reference charts for electrode placement while stimulus amplitude was set according to subject tolerance. Tibialis Anterior (TA) and Vastus Lateralis (VL) muscles of 10 subjects (28.4 ± 8.2 years) were tested in specific dynamometers to measure the evoked isometric torque. The EMG and near-infrared spectroscopy probes were placed on muscle belly to detect the electrical activity and local metabolic modifications of the stimulated muscle, respectively. The stimulation protocol consisted of a gradually increasing frequency ramp from 2 to 50 Hz in 7.5 s. Compared to RC mode, in MP mode the contractile parameters (peak twitch, tetanic torque, area under the torque build-up) and the metabolic solicitation (oxygen consumption and hyperemia due to metabolites accumulation) resulted significantly higher for both TA and VL muscles. MP mode resulted also to be more comfortable for the subjects. Based on the assumption that proper mechanical and metabolic stimuli are necessary to induce muscle strengthening, our results witness the importance of an optimized, i.e., comfortable and effective, stimulation to promote the aforementioned muscle adaptive modifications.
that “fiscal action could be helpful in principle , as fiscal and monetary stimulus together may provide broader support for the economy than monetary...have sought to contain damages spilling over from housing and financial markets to the broader economy , including monetary policy, which is the...including leaving the government holding large amounts of mortgage debt. With the worsening performance of the economy , congressional leaders and
Post, R. B.; Johnson, C. A.
The Malcolm horizon utilizes a large projected light stimulus Peripheral Vision Horizon Device (PVHD) as an attitude indicator in order to achieve a more compelling sense of roll than is obtained with smaller devices. The basic principle is that the larger stimulus is more similar to visibility of a real horizon during roll, and does not require fixation and attention to the degree that smaller displays do. Successful implementation of such a device requires adjustment of the parameters of the visual stimulus so that its effects on motion perception and spatial orientation are optimized. With this purpose in mind, the effects of relevant image variables on the perception of object motion, self motion and spatial orientation are reviewed.
Kearns, David N; Tunstall, Brendan J; Marks, Katherine R; Weiss, Stanley J
Previous studies have suggested that the effects of extinction are response-specific. The present study investigated whether an extinction treatment that eliminated goal tracking elicited by an appetitive conditioned stimulus (CS) would also eliminate the conditioned reinforcing effects of that CS. Rats were first trained on a goal-tracking procedure in which an auditory CS was paired with a food unconditioned stimulus. Animals learned to approach the location where the food was delivered. In a subsequent phase, rats in one group received extinction training that eliminated the goal-tracking elicited by the CS. Rats in the other group did not experience extinction of the food-paired CS. Then, both groups received a test for conditioned reinforcement in which leverpresses resulted in the brief presentation of the stimulus previously paired with food. This stimulus did not act as a conditioned reinforcer in the group that had been subjected to extinction training, but did serve as a conditioned reinforcer in the group that did not experience extinction. These results indicate that the effects of extinction generalize from the approach-eliciting to the conditioned reinforcing effects of an appetitive CS.
Zhuo, Ran; Xue, Hongbo; Chambers, Anna R.; Kolaczyk, Eric; Polley, Daniel B.
Although sensory cortex is thought to be important for the perception of complex objects, its specific role in representing complex stimuli remains unknown. Complex objects are rich in information along multiple stimulus dimensions. The position of cortex in the sensory hierarchy suggests that cortical neurons may integrate across these dimensions to form a more gestalt representation of auditory objects. Yet, studies of cortical neurons typically explore single or few dimensions due to the difficulty of determining optimal stimuli in a high dimensional stimulus space. Evolutionary algorithms (EAs) provide a potentially powerful approach for exploring multidimensional stimulus spaces based on real-time spike feedback, but two important issues arise in their application. First, it is unclear whether it is necessary to characterize cortical responses to multidimensional stimuli or whether it suffices to characterize cortical responses to a single dimension at a time. Second, quantitative methods for analyzing complex multidimensional data from an EA are lacking. Here, we apply a statistical method for nonlinear regression, the generalized additive model (GAM), to address these issues. The GAM quantitatively describes the dependence between neural response and all stimulus dimensions. We find that auditory cortical neurons in mice are sensitive to interactions across dimensions. These interactions are diverse across the population, indicating significant integration across stimulus dimensions in auditory cortex. This result strongly motivates using multidimensional stimuli in auditory cortex. Together, the EA and the GAM provide a novel quantitative paradigm for investigating neural coding of complex multidimensional stimuli in auditory and other sensory cortices. PMID:27622211
Stilp, Christian E.
Objects and events in the sensory environment are generally predictable, making most of the energy impinging upon sensory transducers redundant. Given this fact, efficient sensory systems should detect, extract, and exploit predictability in order to optimize sensitivity to less predictable inputs that are, by definition, more informative. Not only are perceptual systems sensitive to changes in physical stimulus properties, but growing evidence reveals sensitivity both to relative predictability of stimuli and to co-occurrence of stimulus attributes within stimuli. Recent results revealed that auditory perception rapidly reorganizes to efficiently capture covariance among stimulus attributes. Acoustic properties per se were perceptually abandoned, and sounds were instead processed relative to patterns of co-occurrence. Here, we show that listeners’ ability to distinguish sounds from one another is driven primarily by the extent to which they are consistent or inconsistent with patterns of covariation among stimulus attributes and, to a lesser extent, whether they are heard frequently or infrequently. When sounds were heard frequently and deviated minimally from the prevailing pattern of covariance among attributes, they were poorly discriminated from one another. In stark contrast, when sounds were heard rarely and markedly violated the pattern of covariance, they became hyperdiscriminable with discrimination performance beyond apparent limits of the auditory system. Plausible cortical candidates underlying these dramatic changes in perceptual organization are discussed. These findings support efficient coding of stimulus statistical structure as a model for both perceptual and neural organization. PMID:27508391
Recent advances in biology have been driven by chemical analyses of the substances that form living organisms. Such analyses are extremely powerful as way of learning about the static properties of molecular species, but relatively powerless for understanding their dynamic behaviors even though this dynamism is essential for organisms to perform various biological processes that perpetuate their lives. Thus, attempts to identify individual species and molecular interaction cascades that drive specific responses to external stimuli or environmental changes often fail. Here I propose a general strategy to address this problem. The strategy comprises two key elements: functional manipulation of a given protein molecule coupled with close monitoring of its biological effect, and construction of a knowledge base tailored for conjecture-driven experimentation. The original idea for this strategy co-evolved with and greatly helped a series of studies we recently performed to discover critical signal cascades and cellular components that regulate the cell cycle transition from G1 to S phase. PMID:27725475
Chen, Ke Heng; Small, Susan A.
The acoustic change complex (ACC) is an auditory-evoked potential elicited to changes within an ongoing stimulus that indicates discrimination at the level of the auditory cortex. Only a few studies to date have attempted to record ACCs in young infants. The purpose of the present study was to investigate the elicitation of ACCs to long-duration speech stimuli in English-learning 4-month-old infants. ACCs were elicited to consonant contrasts made up of two concatenated speech tokens. The stimuli included native dental-dental /dada/ and dental-labial /daba/ contrasts and a nonnative Hindi dental-retroflex /daDa/ contrast. Each consonant-vowel speech token was 410 ms in duration. Slow cortical responses were recorded to the onset of the stimulus and to the acoustic change from /da/ to either /ba/ or /Da/ within the stimulus with significantly prolonged latencies compared with adults. ACCs were reliably elicited for all stimulus conditions with more robust morphology compared with our previous findings using stimuli that were shorter in duration. The P1 amplitudes elicited to the acoustic change in /daba/ and /daDa/ were significantly larger compared to /dada/ supporting that the brain discriminated between the speech tokens. These findings provide further evidence for the use of ACCs as an index of discrimination ability. PMID:26798343
Chen, Ke Heng; Small, Susan A
The acoustic change complex (ACC) is an auditory-evoked potential elicited to changes within an ongoing stimulus that indicates discrimination at the level of the auditory cortex. Only a few studies to date have attempted to record ACCs in young infants. The purpose of the present study was to investigate the elicitation of ACCs to long-duration speech stimuli in English-learning 4-month-old infants. ACCs were elicited to consonant contrasts made up of two concatenated speech tokens. The stimuli included native dental-dental /dada/ and dental-labial /daba/ contrasts and a nonnative Hindi dental-retroflex /daDa/ contrast. Each consonant-vowel speech token was 410 ms in duration. Slow cortical responses were recorded to the onset of the stimulus and to the acoustic change from /da/ to either /ba/ or /Da/ within the stimulus with significantly prolonged latencies compared with adults. ACCs were reliably elicited for all stimulus conditions with more robust morphology compared with our previous findings using stimuli that were shorter in duration. The P1 amplitudes elicited to the acoustic change in /daba/ and /daDa/ were significantly larger compared to /dada/ supporting that the brain discriminated between the speech tokens. These findings provide further evidence for the use of ACCs as an index of discrimination ability.
Kim, Jongwan; Wedell, Douglas H
Recent investigations of the neural correlates of affect elicited from different modalities have found both modality-general and modality-specific representations (Chikazoe et al., 2014). The implications for how physiological responses to affect differ across stimulus modalities have not been fully investigated. This study examined similarities and differences between physiological signatures of affect derived from two different modes of presentation: visual pictures and auditory music sampled from an affective space defined by valence and arousal. Electromyography recordings for the zygomaticus major (EMGZ) and corrugator supercilii (EMGC) were measured along with heart rate and skin conductance level (SCL). Multidimensional scaling was used to visualize relationships from physiological and behavioral responses, and the observed relationships were statistically evaluated using multivariate and univariate analyses. Results for physiological measures demonstrated that valence was represented in the same general way across modalities, primarily reflected in EMGC responses. Arousal, however, was represented in a modality-specific manner, with SCL and EMGZ sensitive to music-based arousal but not picture-based arousal. Stimulus modality itself was predicted from EMGC. Thus, physiological responses to valence were similar across modalities but physiological responses to arousal differed across modalities. These results support the utility of testing for affective markers across modalities within the same experimental setting to reveal how physiological responses are linked to either affect, stimulus modality or both.
Retell, James D; Becker, Stefanie I; Remington, Roger W
In the context of visual search, surprise is the phenomenon by which a previously unseen and unexpected stimulus exogenously attracts spatial attention. Capture by such a stimulus occurs, by definition, independent of task goals and is thought to be dependent on the extent to which the stimulus deviates from expectations. However, the relative contributions of prior-exposure and explicit knowledge of an unexpected event to the surprise response have not yet been systematically investigated. Here observers searched for a specific color while ignoring irrelevant cues of different colors presented prior to the target display. After a brief familiarization period, we presented an irrelevant motion cue to elicit surprise. Across conditions we varied prior exposure to the motion stimulus - seen versus unseen - and top-down expectations of occurrence - expected versus unexpected - to assess the extent to which each of these factors contributes to surprise. We found no attenuation of the surprise response when observers were pre-exposed to the motion cue and or had explicit knowledge of its occurrence. Our results show that it is neither sufficient nor necessary that a stimulus be new and unannounced to elicit surprise and suggest that the expectations that determine the surprise response are highly context specific.
Dignath, David; Eder, Andreas B
According to a recent extension of the conflict-monitoring theory, conflict between two competing response tendencies is registered as an aversive event and triggers a motivation to avoid the source of conflict. In the present study, we tested this assumption. Over five experiments, we examined whether conflict is associated with an avoidance motivation and whether stimulus conflict or response conflict triggers an avoidance tendency. Participants first performed a color Stroop task. In a subsequent motivation test, participants responded to Stroop stimuli with approach- and avoidance-related lever movements. These results showed that Stroop-conflict stimuli increased the frequency of avoidance responses in a free-choice motivation test, and also increased the speed of avoidance relative to approach responses in a forced-choice test. High and low proportions of response conflict in the Stroop task had no effect on avoidance in the motivation test. Avoidance of conflict was, however, obtained even with new conflict stimuli that had not been presented before in a Stroop task, and when the Stroop task was replaced with an unrelated filler task. Taken together, these results suggest that stimulus conflict is sufficient to trigger avoidance.
Jones, T. A.; Jones, S. M.; Colbert, S.
Transient linear acceleration stimuli have been shown to elicit eighth nerve vestibular compound action potentials in birds and mammals. The present study was undertaken to better define the nature of the adequate stimulus for neurons generating the response in the chicken (Gallus domesticus). In particular, the study evaluated the question of whether the neurons studied are most sensitive to the maximum level of linear acceleration achieved or to the rate of change in acceleration (da/dt, or jerk). To do this, vestibular response thresholds were measured as a function of stimulus onset slope. Traditional computer signal averaging was used to record responses to pulsed linear acceleration stimuli. Stimulus onset slope was systematically varied. Acceleration thresholds decreased with increasing stimulus onset slope (decreasing stimulus rise time). When stimuli were expressed in units of jerk (g/ms), thresholds were virtually constant for all stimulus rise times. Moreover, stimuli having identical jerk magnitudes but widely varying peak acceleration levels produced virtually identical responses. Vestibular response thresholds, latencies and amplitudes appear to be determined strictly by stimulus jerk magnitudes. Stimulus attributes such as peak acceleration or rise time alone do not provide sufficient information to predict response parameter quantities. Indeed, the major response parameters were shown to be virtually independent of peak acceleration levels or rise time when these stimulus features were isolated and considered separately. It is concluded that the neurons generating short latency vestibular evoked potentials do so as "jerk encoders" in the chicken. Primary afferents classified as "irregular", and which traditionally fall into the broad category of "dynamic" or "phasic" neurons, would seem to be the most likely candidates for the neural generators of short latency vestibular compound action potentials.
Krause, Christina M
In the year 1994, Krause et al. published an initial report of acoustically elicited electroencephalogram (EEG) event-related desynchronization (ERD)/ event-related synchronization (ERS) responses. Later, Krause et al. reported of distinct ERD/ERS responses during an auditory memory task: the encoding of acoustic material elicited alpha-frequency ERS whereas retrieval or recognition of the same stimulus material evoked alpha ERD. The research group of Krause and co-workers has published several reports on acoustically evoked ERD/ERS responses utilizing various cognitive tasks and diverse stimuli. Recently, also clinical studies have been initiated. This chapter reviews, summarizes, and discusses the findings on cognition- and memory-related ERD/ERS responses specifically in the auditory stimulus modality.
Winkler, Markus H.; Weyers, Peter; Mucha, Ronald F.; Stippekohl, Bastian; Stark, Rudolf
Rationale Smoking cues are theorized to be conditioned stimuli (CSs) formed by repeated pairing with drug. Smoking paraphernalia can elicit subjective and physiological responses in smokers, indicative of positive affect and motivation to consume. Although these responses are probably the result of conditioning, direct evidence from human conditioning studies with physiological measures of motivational valence is rare. Objective The present study investigated the motivational properties of experimentally conditioned cues for smoking. Methods Thirty-nine smokers completed a differential conditioning protocol. Abstract pictures were used as CSs and single puffs on a cigarette as unconditioned stimulus (US). Skin conductance responses and facial electromyography of the zygomatic, corrugator, and orbicularis oris muscles were measured during conditioning. Results The conditioned cue for smoking (CS+) elicited stronger skin conductance responses and more activity of the zygomatic and orbicularis oris muscles than the CS−. Conclusions These results support the notion that through pairing with smoking, neutral stimuli acquire the ability to elicit preparatory physiological responses, which are assumed to play an important role in the maintenance of addiction and relapse in the natural environment. PMID:20953588
Tremblay, Kelly L; Billings, Curtis; Rohila, Neeru
We examined the effects of stimulus complexity and stimulus presentation rate in ten younger and ten older normal-hearing adults. A 1 kHz tone burst as well as a speech syllable were used to elicit the N1 -P2 complex. Three different interstimulus intervals (ISI) were used (510, 910, and 1510 msec). When stimuli were presented at the medium presentation rate (910 msec ISI), N1 and P2 latencies were prolonged for older listeners in response to the speech stimulus but not the tone stimulus. These age effects were absent when stimuli were presented at a slower rate (1510 msec ISI). Results from this study suggest that rapidly occurring stimulus onsets, either within a stimulus or between stimuli, result in prolonged N1 and P2 responses in older adults. This is especially true when processing complex stimuli such as speech. One potential explanation for this age effect might be age-related refractory differences in younger and older auditory systems. Refractory issues might in turn affect synchronized neural activity underlying the perception of critical time-varying speech cues and may partially explain some of the difficulties older people experience understanding speech.
Keitel, Christian; Andersen, Søren K; Quigley, Cliodhna; Müller, Matthias M
Attention filters behaviorally relevant stimuli from the constant stream of sensory information comprising our environment. Research into underlying neural mechanisms in humans suggests that visual attention biases mutual suppression between stimuli resulting from competition for limited processing resources. As a consequence, processing of an attended stimulus is facilitated. This account makes 2 assumptions: 1) An attended stimulus is released from mutual suppression with competing stimuli and 2) an attended stimulus experiences greater gain in the presence of competing stimuli than when it is presented alone. Here, we tested these assumptions by recording frequency-tagged potentials elicited in early visual cortex that index stimulus-specific processing. We contrasted the processing of a given stimulus when its location was attended or unattended and in the presence or the absence of a nearby competing stimulus. At variance with previous findings, competition similarly suppressed processing of attended and unattended stimuli. Moreover, the magnitude of attentional gain was comparable in the presence or the absence of competing stimuli. We conclude that visuospatial selective attention does not directly modulate mutual suppression between stimuli but instead acts as a signal gain, which biases processing toward attended stimuli independent of competition.
Pothos, Emmanuel M; Chater, Nick; Ziori, Eleni
We examined the learning process with 3 sets of stimuli that have identical symbolic structure but differ in appearance (meaningless letter strings, arrangements of geometric shapes, and sequences of cities). One hypothesis is that the learning process aims to encode symbolic regularity in the same way, largely regardless of appearance. Another is that different types of stimuli bias the learning process to operate in different ways. Using the experimental paradigm of artificial grammar learning, we provided a preliminary test of these hypotheses. In Experiments 1 and 2 we measured performance in terms of grammaticality and found no difference across the 3 sets of stimuli. In Experiment 3 we analyzed performance in terms of both grammaticality and chunk strength. Again we found no differences in performance. Our tentative conclusion is that the learning process aims to encode symbolic regularity independent of stimulus appearance.
Berwick, Robert C; Pietroski, Paul; Yankama, Beracah; Chomsky, Noam
A central goal of modern generative grammar has been to discover invariant properties of human languages that reflect "the innate schematism of mind that is applied to the data of experience" and that "might reasonably be attributed to the organism itself as its contribution to the task of the acquisition of knowledge" (Chomsky, 1971). Candidates for such invariances include the structure dependence of grammatical rules, and in particular, certain constraints on question formation. Various "poverty of stimulus" (POS) arguments suggest that these invariances reflect an innate human endowment, as opposed to common experience: Such experience warrants selection of the grammars acquired only if humans assume, a priori, that selectable grammars respect substantive constraints. Recently, several researchers have tried to rebut these POS arguments. In response, we illustrate why POS arguments remain an important source of support for appeal to a priori structure-dependent constraints on the grammars that humans naturally acquire.
Hecox, K.; Squires, N.; Galambos, R.
Short latency (under 10 msec) responses elicited by bursts of white noise were recorded from the scalps of human subjects. Response alterations produced by changes in the noise burst duration (on-time), inter-burst interval (off-time), and onset and offset shapes were analyzed. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise time but was unaffected by changes in fall time. Increases in stimulus duration, and therefore in loudness, resulted in a systematic increase in latency. This was probably due to response recovery processes, since the effect was eliminated with increases in stimulus off-time. The amplitude of wave V was insensitive to changes in signal rise and fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It was concluded that wave V of the human auditory brainstem evoked response is solely an onset response.
Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng
Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.
Tucker, D A; Dietrich, S; McPherson, D L; Salamat, M T
Auditory middle latency response (AMLR) brain maps were obtained in 11 young adults with normal hearing. AMLR waveforms were elicited with monaural clicks presented at three stimulus intensity levels (50, 70, and 90 dB nHL). Recordings were made for right and left ear stimulus presentations. All recordings were obtained in an eyes open/awake status for each subject. Peak-to-peak amplitudes and absolute latencies of the AMLR Pa and Pb waveforms were measured at the Cz electrode site. Pa and Pb waveforms were present 100 percent of the time in response to the 90 dB nHL presentation. The prevalence of Pa and Pb to the 70 dB nHL presentation varied from 86 to 95 percent. The prevalence of Pa and Pb to the 50 dB nHL stimulus never reached 100 percent, ranging in prevalence from 77 to 68 percent. No significant ear effect was seen for amplitude or latency measures of Pa or Pb. AMLR brain maps of the voltage field distributions of Pa and Pb waveforms showed different topographic features. Scalp topography of the Pa waveform was altered by a reduction in stimulus intensity level. At 90 dB nHL, the Pa brain map showed a large positivity midline over the frontal and central scalp areas. At lower stimulus intensity levels, frontal positivity was reduced, and scalp negativity over occipital regions was increased. Pb scalp topography was also altered by a reduction in stimulus intensity level. Varying the stimulus intensity significantly altered Pa and Pb distributions of amplitude and latency measures. Pa and Pb distributions were skewed regardless of stimulus intensity.
Mocaiber, Izabela; Perakakis, Pandelis; Pereira, Mirtes Garcia; Pinheiro, Walter Machado; Volchan, Eliane; de Oliveira, Letícia; Vila, Jaime
Emotional reactions to threatening situations can be either advantageous for human adaptation or unfavorable for physical and mental health if sustained over prolonged periods of time. These contrasting effects mostly depend on the individual's capacity for emotion regulation. It has been shown, for example, that changing appraisal can alter the course of emotional processing. In the present study, the influence of stimulus appraisal over cardiac reactivity to briefly presented (200ms) mutilation pictures was tested in the context of an affective classification task. Heart rate and reaction time of twenty-four undergraduate students were monitored during the presentation of pictures (neutral or mutilated bodies) in successive blocks. In one condition (real), participants were told that the pictures depicted real events. In the other condition (fictitious), they were told that the pictures were taken from movie scenes. As expected, the results showed a more pronounced bradycardia to mutilation pictures, in comparison to neural pictures, in the real context. In the fictitious context, a significant attenuation of the emotional modulation (defensive bradycardia) was observed. However, this attenuation seemed to be transient because it was only observed in the first presentation block of the fictitious context. Reaction time to classify mutilation pictures, compared to neutral pictures, was slower in both contexts, reflecting the privileged processing of emotionally laden material. The present findings show that even briefly presented mutilation pictures elicit a differential cardiac reactivity and modulate behavioral performance. Importantly, changing stimulus appraisal attenuates the emotional modulation of cardiac reactivity (defensive bradycardia).
Maslovat, Dana; Carlsen, Anthony N.; Franks, Ian M.
We investigated the processes underlying stimulus-response compatibility by using a lateralized auditory stimulus in a simple and choice reaction time (RT) paradigm. Participants were asked to make either a left or right key lift in response to either a control (80dB) or startling (124dB) stimulus presented to either the left ear, right ear, or…
Guest, Duncan; Kent, Christopher; Adelman, James S.
Nosofsky (1983) reported that additional stimulus presentations within a trial increase discriminability in absolute identification, suggesting that each presentation creates an independent stimulus representation, but it remains unclear whether exposure duration or the formation of independent representations improves discrimination in such…
Matthews, William J.; Stewart, Neil; Wearden, John H.
This article explores the widely reported finding that the subjective duration of a stimulus is positively related to its magnitude. In Experiments 1 and 2 we show that, for both auditory and visual stimuli, the effect of stimulus magnitude on the perception of duration depends upon the background: Against a high intensity background, weak stimuli…
Kent, Christopher; Lamberts, Koen
This study investigated the effect of stimulus presentation probability on accuracy and response times in an absolute identification task. Three schedules of presentation were used to investigate the interaction between presentation probability and stimulus position within the set. Data from individual participants indicated strong effects of…
This paper presents the empirical basis for the phenomena known as stimulus overselectivity. Stimulus overselectivity involves responding on the basis of a restricted range of elements or features that are discriminative for reinforcement. The manner in which such a response pattern impedes the skill acquisition in children is identified. A…
Park, Heekyeong; Abellanoza, Cheryl; Schaeffer, James; Gandy, Kellen
Source memory is considered to be the cornerstone of episodic memory that enables us to discriminate similar but different events. In the present fMRI study, we investigated whether neural correlates of source retrieval differed by stimulus content in the medial temporal lobe (MTL) when the item and context had been integrated as a perceptually unitized entity. Participants were presented with a list of items either in verbal or pictorial form overlaid on a colored square and instructed to integrate both the item and context into a single image. At test, participants judged the study status of test items and the color in which studied items were presented. Source recognition invariant of stimulus content elicited retrieval activity in both the left anterior hippocampus extending to the perirhinal cortex and the right posterior hippocampus. Word-selective source recognition was related to activity in the left perirhinal cortex, whereas picture-selective source recognition was identified in the left posterior hippocampus. Neural activity sensitive to novelty detection common to both words and pictures was found in the left anterior and right posterior hippocampus. Novelty detection selective to words was associated with the left perirhinal cortex, while activity sensitive to new pictures was identified in the bilateral hippocampus and adjacent MTL cortices, including the parahippocampal, entorhinal, and perirhinal cortices. These findings provide further support for the integral role of the hippocampus both in source recognition and in detection of new stimuli across stimulus content. Additionally, novelty effects in the MTL reveal the integral role of the MTL cortex as the interface for processing new information. Collectively, the present findings demonstrate the importance of the MTL for both previously experienced and novel events.
Carver, Charles S.; Scheier, Michael F.; Segerstrom, Suzanne C.
Optimism is an individual difference variable that reflects the extent to which people hold generalized favorable expectancies for their future. Higher levels of optimism have been related prospectively to better subjective well-being in times of adversity or difficulty (i.e., controlling for previous well-being). Consistent with such findings, optimism has been linked to higher levels of engagement coping and lower levels of avoidance, or disengagement, coping. There is evidence that optimism is associated with taking proactive steps to protect one's health, whereas pessimism is associated with health-damaging behaviors. Consistent with such findings, optimism is also related to indicators of better physical health. The energetic, task-focused approach that optimists take to goals also relates to benefits in the socioeconomic world. Some evidence suggests that optimism relates to more persistence in educational efforts and to higher later income. Optimists also appear to fare better than pessimists in relationships. Although there are instances in which optimism fails to convey an advantage, and instances in which it may convey a disadvantage, those instances are relatively rare. In sum, the behavioral patterns of optimists appear to provide models of living for others to learn from. PMID:20170998
Hagler, Donald J.
Studying how the timing and amplitude of visual evoked responses (VERs) vary between visual areas is important for understanding visual processing but is complicated by difficulties in reliably estimating VERs in individual visual areas using non-invasive brain measurements. Retinotopy constrained source estimation (RCSE) addresses this challenge by using multiple, retinotopically-mapped stimulus locations to simultaneously constrain estimates of VERs in visual areas V1, V2, and V3, taking advantage of the spatial precision of fMRI retinotopy and the temporal resolution of magnetoencephalography (MEG) or electroencephalography (EEG). Nonlinear optimization of dipole locations, guided by a group-constrained RCSE solution as a prior, improved the robustness of RCSE. This approach facilitated the analysis of differences in timing and amplitude of VERs between V1, V2, and V3, elicited by stimuli with varying luminance contrast in a sample of eight adult humans. The V1 peak response was 37% larger than that of V2 and 74% larger than that of V3, and also ~10–20 msec earlier. Normalized contrast response functions were nearly identical for the three areas. Results without dipole optimization, or with other nonlinear methods not constrained by prior estimates were similar but suffered from greater between-subject variability. The increased reliability of estimates offered by this approach may be particularly valuable when using a smaller number of stimulus locations, enabling a greater variety of stimulus and task manipulations. PMID:23868690
Lefave, M K; Neufeld, R W
The experiment investigated cardiac deceleration responses to repeated presentations of an aversive visual stimulus (a slide of a mutilated homicide victim) as a function of interspersing presentations of different types of other provocative visual stimuli amidst the aversive stimulus. 30 male volunteers were divided into three groups of 10 subjects each. One group viewed the aversive stimulus randomly interspersed with presentations of female nudes (positive context); a second group viewed the aversive stimulus amidst presentations of slides of skin-disease patients (negative context); and the third group viewed the aversive slide surrounded by presentations of other male undergraduates (neutral context). After repeatedly viewing the single homocide-victim slide, subjects viewed five different homicide scenes without contextual slides. These identical procedures were repeated during a second experimental session. A significant context-by-sessions interaction (p less than .05) reflected a decrement in cardiac deceleration over sessions for the positive context and an increase in deceleration from the first to the second session for the negative context. The neutral context did not affect cardiac deceleration over sessions. The series of different homicide scenes elicited greater cardiac deceleration than repeated exposures to the same slide. These results were discussed in terms of the possible role of stimulus context in affecting attention and vigilant-avoidant coping orientations.
Tapia, Evelina; Mazzi, Chiara; Savazzi, Silvia; Beck, Diane M
Transcranial magnetic stimulation (TMS) applied over the occipital lobe approximately 100 ms after the onset of a stimulus decreases its visibility if it appears in the location of the phosphene. Because phosphenes can also be elicited by stimulation of the parietal regions, we asked if the same procedure that is used to reduce visibility of stimuli with occipital TMS will lead to decreased stimulus visibility when TMS is applied to parietal regions. TMS was randomly applied at 0-130 ms after the onset of the stimulus in steps of 10 ms in occipital and parietal regions. Participants responded to the orientation of the line stimulus and rated its visibility. We replicate previous reports of phosphenes from both occipital and parietal TMS. As previously reported, we also observed visual suppression around the classical 100 ms window both in the objective line orientation and subjective visibility responses with occipital TMS. Parietal stimulation, on the other hand, did not consistently reduce stimulus visibility in any time window.
Andreatta, Marta; Mühlberger, Andreas; Glotzbach-Schoon, Evelyn; Pauli, Paul
Relief from pain is positively valenced and entails reward-like properties. Notably, stimuli that became associated with pain relief elicit reward-like implicit responses too, but are explicitly evaluated by humans as aversive. Since the unpredictability of pain makes pain more aversive, this study examined the hypotheses that the predictability of pain also modulates the valence of relief-associated stimuli. In two studies, we presented one conditioned stimulus (FORWARDCS+) before a painful unconditioned stimulus (US), another stimulus (BACKWARDCS+) after the painful US, and a third stimulus (CS−) was never associated with the US. In Study 1, FORWARDCS+ predicted half of the USs while the other half was delivered unwarned and followed by BACKWARDCS+. In Study 2, all USs were predicted by FORWARDCS+ and followed by BACKWARDCS+. In Study 1 both FORWARDCS+ and BACKWARDCS+ were rated as negatively valenced and high arousing after conditioning, while BACKWARDCS+ in Study 2 acquired positive valence and low arousal. Startle amplitude was significantly attenuated to BACKWARDCS+ compared to FORWARDCS+ in Study 2, but did not differ among CSs in Study 1. In summary, predictability of aversive events reverses the explicit valence of a relief-associated stimulus. PMID:24068989
Uhrig, Meike K.; Trautmann, Nadine; Baumgärtner, Ulf; Treede, Rolf-Detlef; Henrich, Florian; Hiller, Wolfgang; Marschall, Susanne
Pictures and film clips are widely used and accepted stimuli to elicit emotions. Based on theoretical arguments it is often assumed that the emotional effects of films exceed those of pictures, but to date this assumption has not been investigated directly. The aim of the present study was to compare pictures and films in terms of their capacity to induce emotions verified by means of explicit measures. Stimuli were (a) single pictures presented for 6 s, (b) a set of three consecutive pictures with emotionally congruent contents presented for 2 s each, (c) short film clips with a duration of 6 s. A total of 144 participants rated their emotion and arousal states following stimulus presentation. Repeated-measures ANOVAs revealed that the film clips and 3-picture version were as effective as the classical 1-picture method to elicit positive emotions, however, modulation toward positive valence was little. Modulation toward negative valence was more effective in general. Film clips were less effective than pictorial stimuli in producing the corresponding emotion states (all p < 0.001) and were less arousing (all p ≤ 0.02). Possible reasons for these unexpected results are discussed. PMID:26925007
Wang, Tao; Huang, Jiang-hua; Lin, Lin; Zhan, Chang'an A
To obtain reliable transient auditory evoked potentials (AEPs) from EEGs recorded using high stimulus rate (HSR) paradigm, it is critical to design the stimulus sequences of appropriate frequency properties. Traditionally, the individual stimulus events in a stimulus sequence occur only at discrete time points dependent on the sampling frequency of the recording system and the duration of stimulus sequence. This dependency likely causes the implementation of suboptimal stimulus sequences, sacrificing the reliability of resulting AEPs. In this paper, we explicate the use of continuous-time stimulus sequence for HSR paradigm, which is independent of the discrete electroencephalogram (EEG) recording system. We employ simulation studies to examine the applicability of the continuous-time stimulus sequences and the impacts of sampling frequency on AEPs in traditional studies using discrete-time design. Results from these studies show that the continuous-time sequences can offer better frequency properties and improve the reliability of recovered AEPs. Furthermore, we find that the errors in the recovered AEPs depend critically on the sampling frequencies of experimental systems, and their relationship can be fitted using a reciprocal function. As such, our study contributes to the literature by demonstrating the applicability and advantages of continuous-time stimulus sequences for HSR paradigm and by revealing the relationship between the reliability of AEPs and sampling frequencies of the experimental systems when discrete-time stimulus sequences are used in traditional manner for the HSR paradigm.
Wang, Tao; Huang, Jiang-hua; Lin, Lin
To obtain reliable transient auditory evoked potentials (AEPs) from EEGs recorded using high stimulus rate (HSR) paradigm, it is critical to design the stimulus sequences of appropriate frequency properties. Traditionally, the individual stimulus events in a stimulus sequence occur only at discrete time points dependent on the sampling frequency of the recording system and the duration of stimulus sequence. This dependency likely causes the implementation of suboptimal stimulus sequences, sacrificing the reliability of resulting AEPs. In this paper, we explicate the use of continuous-time stimulus sequence for HSR paradigm, which is independent of the discrete electroencephalogram (EEG) recording system. We employ simulation studies to examine the applicability of the continuous-time stimulus sequences and the impacts of sampling frequency on AEPs in traditional studies using discrete-time design. Results from these studies show that the continuous-time sequences can offer better frequency properties and improve the reliability of recovered AEPs. Furthermore, we find that the errors in the recovered AEPs depend critically on the sampling frequencies of experimental systems, and their relationship can be fitted using a reciprocal function. As such, our study contributes to the literature by demonstrating the applicability and advantages of continuous-time stimulus sequences for HSR paradigm and by revealing the relationship between the reliability of AEPs and sampling frequencies of the experimental systems when discrete-time stimulus sequences are used in traditional manner for the HSR paradigm. PMID:23606900
Wang, Shuo; Hu, Jiong; Dong, Ruijuan; Liu, Dongxin; Chen, Jing; Musacchia, Gabriella; Liu, Bo
Background: Perceptual and electrophysiological studies have found reduced speech discrimination in quiet and noisy environment, delayed neural timing, decreased neural synchrony, and decreased temporal processing ability in elderlies, even those with normal hearing. However, recent studies have also demonstrated that language experience and auditory training enhance the temporal dynamics of sound encoding in the auditory brainstem response (ABR). The purpose of this study was to explore the pitch processing ability at the brainstem level in an aging population that has a tonal language background. Method: Mandarin speaking younger (n = 12) and older (n = 12) adults were recruited for this study. All participants had normal audiometric test results and normal suprathreshold click-evoked ABR. To record frequency following responses (FFRs) elicited by Mandarin lexical tones, two Mandarin Chinese syllables with different fundamental frequency pitch contours (Flat Tone and Falling Tone) were presented at 70 dB SPL. Fundamental frequencies (f0) of both the stimulus and the responses were extracted and compared to individual brainstem responses. Two indices were used to examine different aspects of pitch processing ability at the brainstem level: Pitch Strength and Pitch Correlation. Results: Lexical tone elicited FFR were overall weaker in the older adult group compared to their younger adult counterpart. Measured by Pitch Strength and Pitch Correlation, statistically significant group differences were only found when the tone with a falling f0 (Falling Tone) were used as the stimulus. Conclusion: Results of this study demonstrated that in a tonal language speaking population, pitch processing ability at the brainstem level of older adults are not as strong and robust as their younger counterparts. Findings of this study are consistent with previous reports on brainstem responses of older adults whose native language is English. On the other hand, lexical tone elicited
Steenbergen, Peter; Buitenweg, Jan R; Trojan, Jörg; Veltink, Peter H
Few experimental data are available about the influence of stimulus intensity on localization of cutaneous stimuli. The localization behavior of an individual as function of the veridical stimulus sites can be represented in the form of a perceptual map. It is unknown how the intensity of cutaneous stimuli influences these perceptual maps. We investigated the effect of stimulus intensity on trial-to-trial localization variability and on perceptual maps. We applied non-painful electrocutaneous stimuli of three different intensities through seven surface electrodes on the lower arm of healthy participants. They localized the stimuli on a tablet monitor mounted directly above their arm, on which a photograph of this arm was presented. The length of the arm over which the stimuli were localized was contracted when compared to the real electrode positions. This length increased toward veridical with increasing stimulus intensity. The trial-to-trial variance of the localizations dropped significantly with increasing intensity. Furthermore, localization biases of individual stimulus positions were shown to decrease with increasing stimulus intensity. We conclude that tactile stimuli are localized closer to veridical with increasing intensity in two respects: the localizations become more consistent and more accurate.
Dube, William V; Dickson, Chata A; Balsamo, Lyn M; O'Donnell, Kristin Lombard; Tomanari, Gerson Y; Farren, Kevin M; Wheeler, Emily E; McIlvane, William J
Restricted stimulus control refers to discrimination learning with atypical limitations in the range of controlling stimuli or stimulus features. In the study reported here, 4 normally capable individuals and 10 individuals with intellectual disabilities (ID) performed two-sample delayed matching to sample. Sample-stimulus observing was recorded with an eye-tracking apparatus. High accuracy scores indicated stimulus control by both sample stimuli for the 4 nondisabled participants and 4 participants with ID, and eye tracking data showed reliable observing of all stimuli. Intermediate accuracy scores indicated restricted stimulus control for the remaining 6 participants. Their eye-tracking data showed that errors were related to failures to observe sample stimuli and relatively brief observing durations. Five of these participants were then given interventions designed to improve observing behavior. For 4 participants, the interventions resulted initially in elimination of observing failures, increased observing durations, and increased accuracy. For 2 of these participants, contingencies sufficient to maintain adequate observing were not always sufficient to maintain high accuracy; subsequent procedure modifications restored it, however. For the 5th participant, initial improvements in observing were not accompanied by improved accuracy, an apparent instance of observing without attending; accuracy improved only after an additional intervention that imposed contingencies on observing behavior. Thus, interventions that control observing behavior seem necessary but may not always be sufficient for the remediation of restricted stimulus control. PMID:21541173
Brascamp, Jan; Sohn, Hansem; Lee, Sang-Hun; Blake, Randolph
When corresponding areas of the two eyes view dissimilar images, stable perception gives way to visual competition wherein perceptual awareness alternates between those images. Moreover, a given image can remain visually dominant for several seconds at a time even when the competing images are swapped between the eyes multiple times each second. This perceptual stability across eye swaps has led to the widespread belief that this unique form of visual competition, dubbed stimulus rivalry, is governed by eye-independent neural processes at a purely binocular stage of cortical processing. We tested this idea by investigating the influence of stimulus rivalry on the buildup of the threshold elevation aftereffect, a form of contrast adaptation thought to transpire at early cortical stages that include eye-specific neural activity. Weaker threshold elevation aftereffects were observed when the adapting image was engaged in stimulus rivalry than when it was not, indicating diminished buildup of adaptation during stimulus-rivalry suppression. We then confirmed that this reduction occurred, in part, at eye-specific neural stages by showing that suppression of an image at a given moment specifically diminished adaptation associated with the eye viewing the image at that moment. Considered together, these results imply that eye-specific neural events at early cortical processing stages contribute to stimulus rivalry. We have developed a computational model of stimulus rivalry that successfully implements this idea.
O’Neale, Ashley; Ellis, Joseph; Creton, Robbert; Colwill, Ruth M.
Learning about a moving visual stimulus was examined in zebrafish larvae using an automated imaging system and a t1-t2 design. In three experiments, zebrafish larvae were exposed to one of two inputs at t1 (either a gray bouncing disk or an identical but stationary disk) followed by a common test at t2 (the gray bouncing disk). Using 7 days post-fertilization (dpf) larvae and 12 stimulus exposures, Experiment 1 established that these different treatments produced differential responding to the moving disk during testing. Larvae familiar with the moving test stimulus were significantly less likely to be still in its presence than larvae that had been exposed to the identical but stationary stimulus. Experiment 2 confirmed this result in 7 dpf larvae and extended the finding to 5 and 6 dpf larvae. Experiment 3 found differential responding to the moving test stimulus with 4 or 8 stimulus exposures but not with just one exposure in 7 dpf larvae. These results provide evidence for learning in very young zebrafish larvae. The merits and challenges of the t1-t2 framework to study learning are discussed. PMID:24012906
Antonio-Santos, Aileen; Vedula, Satyanarayana S; Hatt, Sarah R; Powell, Christine
Background Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the passage of light secondary to a condition such as cataract. The obstruction prevents formation of a clear image on the retina. SDA can be resistant to treatment, leading to poor visual prognosis. SDA probably constitutes less than 3% of all amblyopia cases, although precise estimates of prevalence are unknown. In developed countries, most patients present under the age of one year; in less developed parts of the world patients are likely to be older at the time of presentation. The mainstay of treatment is removal of the cataract and then occlusion of the better-seeing eye, but regimens vary, can be difficult to execute, and traditionally are believed to lead to disappointing results. Objectives Our objective was to evaluate the effectiveness of occlusion therapy for SDA in an attempt to establish realistic treatment outcomes. Where data were available, we also planned to examine evidence of any dose response effect and to assess the effect of the duration, severity, and causative factor on the size and direction of the treatment effect. Search methods We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2013, Issue 9), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to October 2013), EMBASE (January 1980 to October 2013), the Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2013), PubMed (January 1946 to October 2013), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 28 October 2013. Selection criteria We planned
Timberlake, W; Lucas, G A
This research examined three explanations for the "superstitious" behavior of pigeons under frequent fixed-time delivery of food: accidental response-reward contingency, stimulus substitution, and elicited species-typical appetitive behavior. The behavior observed in these studies consisted of occasional postfood locomotion away from the food hopper, and a predominant pattern of activity directed toward the hopper wall (wall-directed behavior), including approaching, stepping side to side, scratching with the feet, bumping with the breast, pendulum movements of the extended neck, and head bobbing, though not pecking. The consistency of these behavior patterns argued against explanation by accidental response contingencies, and the complexity of behavior was incompatible with the classic stimulus-substitution account. These studies also showed that: (1) response contingencies and prior stimulus experience can modify wall-directed behavior, but within definable limits; (2) pecking sometimes can be obtained in birds of specific strains, and by providing extended training; (3) placing the hopper in the floor at the center of a large chamber replaces wall-directed behavior with circling in a manner that resembles ground foraging for food. We conclude that superstitious behavior under periodic delivery of food probably develops from components of species-typical patterns of appetitive behavior related to feeding. These patterns are elicited by a combination of frequent food presentations and the supporting stimuli present in the environment. PMID:4086972
Fu, Kai; Qu, Lintao; Shimada, Steven G; Nie, Hong; LaMotte, Robert H
Chemical pruritogens and algogens evoke primarily itch and pain, respectively, when administered to the skin of healthy human subjects. However, the dominant sensory quality elicited by an algesic chemical stimulus may change in patients with chronic itch where bradykinin, elicits itch in addition to pain. Here we tested whether normally pruritic and algesic chemicals evoked abnormal itch- or pain-like behaviors in the mouse after the development of contact hypersensitivity (CHS), an animal model of allergic contact dermatitis. Mice previously sensitized to a hapten (squaric acid dibutylester) applied to the abdomen, exhibited spontaneous itch-like scratching and pain-like wiping directed to the site on the cheek of the CHS elicited by a subsequent challenge with the same hapten. In comparison with responses of control mice, CHS mice exhibited a significant increase in the scratching evoked by bovine adrenal medulla 8-22, a peptide that elicits a histamine-independent itch, but did not alter the scratching to histamine. Bradykinin, an algogen that elicited only wiping in control mice, additionally evoked significant scratching in CHS mice. Thus, within an area of CHS, histamine-independent itch is enhanced and chemically evoked pain is accompanied by itch.
Preminger, Son; Harmelech, Tal; Malach, Rafael
Despite extensive research of the Default network, a set of regions which tend to reduce their activity relative to rest in response to stimulus-driven tasks, its function is still debated. Specifically, it is still not clear to what extent the activation profile of this network is driven by processes related to external stimulation (inhibitory or anticipatory), or is driven by specific thought contents. To address this question, we examined the ability of thoughts, generated in the absence of external stimulation, to modulate default network activation. In a set of experiments, several types of long lasting stimulus-free thoughts were elicited by brief (<1s) auditory cues. Sustained (40s) brain activations, far outlasting the cue, were demonstrated during these stimulus-free conditions. Importantly, brain activity in the default network showed a striking modulation associated with stimulus-free thought content. More specifically, a preferential activation was observed in essentially the entire default network during volitional-prospection thoughts when compared to the other stimulus-free thought conditions. Furthermore, several regions of the default network showed long-lasting above rest activations during the volitional-prospection condition. Our results demonstrate that default network activation can be modulated in the absence of external stimuli, thus pointing to the importance of thought-content in default-network specialization. Furthermore, together with previous research, these results support the notion that intrinsically oriented processing is a core specialization of the default network. Finally, our stimulus-free experimental paradigm introduces a new method for studying default network functionality.
Brino, Ana Leda F., Barros, Romariz S., Galvao, Ol; Garotti, M.; Da Cruz, Ilara R. N.; Santos, Jose R.; Dube, William V.; McIlvane, William J.
This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys ("Cebus apella"). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The…
Minster, Sara Tepaeru; Elliffe, Douglas; Muthukumaraswamy, Suresh D.
We aimed to investigate whether novel stimulus relations would emerge from stimulus correlations when those relations explicitly conflicted with reinforced relations. In a symbolic matching-to-sample task using kanji characters as stimuli, we arranged class-specific incorrect comparison stimuli in each of three classes. After presenting either Ax…
Mathewson, Kyle E.; Gratton, Gabriele; Fabiani, Monica; Beck, Diane M.; Ro, Tony
We often fail to see something that at other times is readily detectable. Because the visual stimulus itself is unchanged, this variability in conscious awareness is likely related to changes in the brain. Here we show that the phase of EEG alpha rhythm measured over posterior brain regions can reliably predict both subsequent visual detection and stimulus-elicited cortical activation levels in a metacontrast masking paradigm. When a visual target presentation coincides with the trough of an alpha wave, cortical activation is suppressed as early as 100 ms after stimulus onset, and observers are less likely to detect the target. Thus, during one alpha cycle lasting 100 ms, the human brain goes through a rapid oscillation in excitability, which directly influences the probability that an environmental stimulus will reach conscious awareness. Moreover, ERPs to the appearance of a fixation cross before the target predict its detection, further suggesting that cortical excitability level may mediate target detection. A novel theory of cortical inhibition is proposed in which increased alpha power represents a “pulsed inhibition” of cortical activity that affects visual awareness. PMID:19261866
Asli, Ole; Kulvedrøsten, Silje; Solbakken, Line E; Flaten, Magne Arve
The latency of conditioned fear after delay and trace conditioning was investigated. Some argue that delay conditioning is not dependent on awareness. In contrast, trace conditioning, where there is a gap between the conditioned stimulus (CS) and the unconditioned stimulus (US), is assumed to be dependent on awareness. In the present study, a tone CS signaled a noise US presented 1000 ms after CS onset in the delay conditioning group. In the trace conditioning group, a 200-ms tone CS was followed by an 800-ms gap prior to US presentation. Fear-potentiated startle should be seen at shorter intervals after delay conditioning compared to trace conditioning. Analyses showed increased startle at 30, 50, 100, and 150 ms after CS onset following delay conditioning compared to trace conditioning. This implies that fear-relevant stimuli elicit physiological reactions before extended processing of the stimuli occur, following delay, but not trace conditioning.
Nagarkar, Sanjog S; Desai, Aamod V; Ghosh, Sujit K
Materials that can recognize the changes in their local environment and respond by altering their inherent physical and/or chemical properties are strong candidates for future "smart" technology materials. Metal-organic frameworks (MOFs) have attracted a great deal of attention in recent years owing to their designable architecture, host-guest chemistry, and softness as porous materials. Despite this fact, studies on the tuning of the properties of MOFs by external stimuli are still rare. This review highlights the recent developments in the field of stimulus-responsive MOFs or so-called smart MOFs. In particular, the various stimuli used and the utility of stimulus-responsive smart MOFs for various applications such as gas storage and separation, sensing, clean energy, catalysis, molecular motors, and biomedical applications are highlighted by using representative examples. Future directions in the developments of stimulus-responsive smart MOFs and their applications are proposed from a personal perspective.
Takahashi, Kohske; Fukuda, Haruaki; Samejima, Kazuyuki; Watanabe, Katsumi; Ueda, Kazuhiro
In the uncanny valley phenomenon, the causes of the feeling of uncanniness as well as the impact of the uncanniness on behavioral performances still remain open. The present study investigated the behavioral effects of stimulus uncanniness, particularly with respect to speeded response. Pictures of fish were used as visual stimuli. Participants engaged in direction discrimination, spatial cueing, and dot-probe tasks. The results showed that pictures rated as strongly uncanny delayed speeded response in the discrimination of the direction of the fish. In the cueing experiment, where a fish served as a task-irrelevant and unpredictable cue for a peripheral target, we again observed that the detection of a target was slowed when the cue was an uncanny fish. Conversely, the dot-probe task suggested that uncanny fish, unlike threatening stimulus, did not capture visual spatial attention. These results suggested that stimulus uncanniness resulted in the delayed response, and importantly this modulation was not mediated by the feelings of threat.
Katz, Jonathan L
By the mid-1960s, the concept that drugs can function as reinforcing stimuli through response-reinforcer contingencies had created a paradigm shift in drug abuse science. Steve Goldberg's first several publications focused instead on stimulus-stimulus contingencies (respondent conditioning) in examining Abraham Wikler's two-factor hypothesis of relapse involving conditioned withdrawal and reinforcing effects of drugs. Goldberg provided a compelling demonstration that histories of contingencies among stimuli could produce lasting withdrawal reactions in primates formerly dependent on opioids. Other studies conducted by Goldberg extended the analysis of effects of stimulus-stimulus contingencies on behavior maintained by opioid reinforcing effects and showed that withdrawal-inducing antagonist administration can produce conditioned increases in self-administration. Subsequent studies of the effects of stimuli associated with cocaine injection under second-order schedules showed that the maintenance of behavior with drug injections was in most important aspects similar to the maintenance of behavior with more conventional reinforcers when the behavior-disrupting pharmacological effects of the drugs were minimized. Studies on second-order schedules demonstrated a wide array of conditions under which behavior could be maintained by drug injection and further influenced by stimulus-stimulus contingencies. These schedules present opportunities to produce in the laboratory complex situations involving response- and stimulus-stimulus contingencies, which go beyond simplistic pairings of stimuli and more closely approximate those found with human drug abusers. A focus on the response- and stimulus-stimulus contingencies, and resulting quantifiable changes in objective and quantifiable behavioral endpoints exemplified by the studies by Steve Goldberg, remains the most promising way forward for studying problems of drug dependence.
Haines, Richard F.; Kiefel, Steven M.
Four independent variables of visual perception during binocular viewing were studied. In 24 observers, the vertical displacement threshold (DT) sensitivity along the horizontal meridian was determined as a function of the rate, duration, and length of the stimulus. It was found that the DT increases with an increased angular separation of the stimulus image from the fovea (i.e., the stimulus must move farther in order to be correctly discriminated as having moved). In addition, it was found that the sensitivity to the stimulus displacement increases with increasing of the stimulus length, duration, and/or angular rate. These findings are related to the design optimization of dynamic attitude displays and symbology for aircraft.
Meier, Matt E.; Kane, Michael J.
Three experiments examined the relation between working memory capacity (WMC) and two different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (SR) interference. Our goal was to test whether WMC’s relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict trials, plus trials that combined the two conflict types. We limited ostensible goal-maintenance contributions to performance by requiring the same goal for all trial types and by presenting frequent conflict trials that reinforced the goal. WMC predicted resolution of S-S conflict as expected: Higher-WMC subjects showed reduced response time interference. Although WMC also predicted S-R interference, here, higher-WMC subjects showed increased error interference. Experiment 2A replicated these results in a version of the conflict task without combined S-S/S-R trials. Experiment 2B increased the proportion of congruent (non-conflict) trials to promote reliance on goal-maintenance processes. Here, higher-WMC subjects resolved both S-S and S-R conflict more successfully than did lower-WMC subjects. The results were consistent with Kane and Engle’s (2003) two-factor theory of cognitive control, according to which WMC predicts executive-task performance through goal-maintenance and conflict-resolution processes. However, the present results add specificity to the account by suggesting that higher-WMC subjects better resolve cognitive conflict because they more efficiently select relevant stimulus features against irrelevant, distracting ones. PMID:26120774
Meier, Matt E; Kane, Michael J
Three experiments examined the relation between working memory capacity (WMC) and 2 different forms of cognitive conflict: stimulus-stimulus (S-S) and stimulus-response (S-R) interference. Our goal was to test whether WMC's relation to conflict-task performance is mediated by stimulus-identification processes (captured by S-S conflict), response-selection processes (captured by S-R conflict), or both. In Experiment 1, subjects completed a single task presenting both S-S and S-R conflict trials, plus trials that combined the 2 conflict types. We limited ostensible goal-maintenance contributions to performance by requiring the same goal for all trial types and by presenting frequent conflict trials that reinforced the goal. WMC predicted resolution of S-S conflict as expected: Higher WMC subjects showed reduced response time interference. Although WMC also predicted S-R interference, here, higher WMC subjects showed increased error interference. Experiment 2A replicated these results in a version of the conflict task without combined S-S/S-R trials. Experiment 2B increased the proportion of congruent (nonconflict) trials to promote reliance on goal-maintenance processes. Here, higher WMC subjects resolved both S-S and S-R conflict more successfully than did lower WMC subjects. The results were consistent with Kane and Engle's (2003) 2-factor theory of cognitive control, according to which WMC predicts executive-task performance through goal-maintenance and conflict-resolution processes. However, the present results add specificity to the account by suggesting that higher WMC subjects better resolve cognitive conflict because they more efficiently select relevant stimulus features against irrelevant, distracting ones.
Lee, Samuel; Miles, James D; Vu, Kim-Phuong L
Responses are faster and more accurate when they are spatially compatible with a stimulus than when they are incompatible (the stimulus-response compatibility (SRC) effect). In studies using two-dimensional (2-D) stimulus and response sets in which stimuli and responses have both vertical (top-bottom) and horizontal (right-left) spatial relations, SRC effects are generally larger along the horizontal dimension, an effect called right-left prevalence. Several accounts have been posited to explain this asymmetry, including frames of reference to the body and spatio-anatomical constraints. We propose a new account of the right-left prevalence effect in which prevalence effects are largely determined by the spatial alignment between elements on the stimulus display and response locations on the control panel--the control-display alignment (CDA). For example, when responses are aligned below a display, 2-D stimulus and response sets share a common vertical midline that emphasizes a right-left distinction. When responses are to the right or left of the display, the shared midline is horizontal, emphasizing the top-bottom distinction and should instead lead to top-bottom prevalence effects. Participants completed two-choice, 2-D SRC tasks in four control-display configurations with a response panel centered above, below, left, and right of a projected display. As hypothesized, right-left prevalence was elicited using vertical CDA and top-bottom prevalence was elicited using horizontal CDA. The findings demonstrate that CDA largely determines prevalence effects and should be taken into account when using multidimensional stimulus and response sets.
Lucot, James B.; Crampton, George H.
Vomiting was suppressed in cats pretreated with 8-OH-DPAT and then challenged with an emetic stimulus; motion, xylazine or cisplatin. The antiemetic effect is likely due to stimulation of postsynaptic serotonin-1A receptors. The most parsimonious explanation is that it acts at a convergent structure, presumably at or near the vomiting center. If so, 8-OH-DPAT may block emesis elicited by virtually any other stimulus. A supplementary experiment revealed that lorazepam suppressed motion sickness at a dose that produced ataxia, but did not suppress xylazine-induced emesis. These results do not support the possibility that the antiemetic effects of 8-OH-DPAT were the result of anxiolytic activity.
Construction bonding authority--a technical, and often obscure, source of capital funding for school districts--has emerged as a hot ticket for those looking to finance school facilities work under the federal government's economic-stimulus program. School districts left out of the loop for direct funding are lining up for some of at least $24…
Cavanagh, Sean; Hollingsworth, Heather
States are finally arriving at the "funding cliff"--the point where about $100 billion in federal economic-stimulus aid for education runs out. The loss seems certain to compound severe budget woes and could mean thousands of school layoffs and the elimination of popular programs and services in districts across the country. The bulk of…
Haimson, Barry; Wilkinson, Krista M.; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J.
Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g.,…
Hoff, David J.
As Congress began debate last week over the size and scope of more than $120 billion in proposed emergency education aid, state leaders were anxiously awaiting the details so they could make specific plans to spend the economic-stimulus money. Governors, state legislators, and state schools chiefs have yet to learn what rules Congress will attach…
Poverty of the stimulus (POS) arguments have instigated considerable debate in the recent linguistics literature. This article uses the comparative method to challenge the logic of POS arguments. Rather than question the premises of POS arguments, the article demonstrates how POS arguments for individual languages lead to a "reductio ad absurdum"…
BARNES, C D; KATZUNG, B G
Orientation in the monopolar pulse field used as the unconditioned stimulus was found to influence formation of a conditioned response to light in planarians. Planarians trained while oriented with the head toward the cathode reached maximal response rates rapidly, while those trained while oriented toward the anode showed no evidence of conditioned response formation.
Mullen, Patricia A.; Whitehead, Robert L.
Compared with 20 normal speaking and 20 articulation defective Ss (7 and 8 years old) was the percent of correct initial identification of stimulus pictures on the Goldman-Fristoe Test of Articulation with the percent correct identification on the Arizona Articulation Proficiency Scale. (Author/IM)
Kam, Xuan-Nga Cao; Stoyneshka, Iglika; Tornyova, Lidiya; Fodor, Janet D.; Sakas, William G.
Recent challenges to Chomsky's "poverty of the stimulus" thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports…
Sundberg, Mark L.
The importance of the intraverbal relation is missed in most theories of language. Skinner (1957) attributes this to traditional semantic theories of meaning that focus on the nonverbal referents of words and neglect verbal stimuli as separate sources of control for linguistic behavior. An analysis of verbal stimulus control is presented, along…
Weiss, Stanley J; Kearns, David N; Cohn, Scott I; Schindler, Charles W; Panlilio, Leigh V
Environmental stimuli that set the occasion wherein drugs are acquired can "trigger" drug-related behavior. Investigating the stimulus control of drug self-administration in laboratory animals should help us better understand this aspect of human drug abuse. Stimulus control of cocaine self-administration was generated here for the first time using multiple and chained schedules with short, frequently-alternating components--like those typically used to study food-maintained responding. The procedures and results are presented along with case histories to illustrate the strategies used to produce this stimulus control. All these multicomponent schedules contained variable-interval (VI) components as well as differential-reinforcement-of-other-behavior (DRO) or extinction components. Schedule parameters and unit dose were adjusted for each rat to produce stable, moderate rates in VI components, with minimal postreinforcement (infusion) pausing, and response cessation in extinction and DRO components. Whole-body drug levels on terminal baselines calculated retrospectively revealed that all rats maintained fairly stable drug levels (mean, 2.3 to 3.4 mg/kg) and molar rates of intake (approximately 6.0 mg/kg/hr). Within this range, no relation between local VI response rates and drug level was found. The stimulus control revealed in cumulative records was indistinguishable from that achieved with food under these schedules, suggesting that common mechanisms may underlie the control of cocaine- and food-maintained behavior. PMID:12696744
66027-0347 Ba. NAME OF FUNDING/SPONSORING 8b. OFFICE SYMBOL 9. PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORPANIZATION U.S. Army Research (If...Method (CDM) has been developed as a knowledge elicitation tool for probing proficient decision making. This report describes the use of CDM during...knowledge elicitation can be used in Army Command and Control (Ce) exercises as a means of understanding decision-making dynamics. Such a tool could
He, Jia; Sun, Hong-Qiang; Li, Su-Xia; Zhang, Wei-Hua; Shi, Jie; Ai, Si-Zhi; Li, Yun; Li, Xiao-Jun; Tang, Xiang-Dong; Lu, Lin
Study Objectives: Repeated exposure to a neutral conditioned stimulus (CS) in the absence of a noxious unconditioned stimulus (US) elicits fear memory extinction. The aim of the current study was to investigate the effects of mild tone exposure (CS) during slow wave sleep (SWS) on fear memory extinction in humans. Design: The healthy volunteers underwent an auditory fear conditioning paradigm on the experimental night, during which tones served as the CS, and a mild shock served as the US. They were then randomly assigned to four groups. Three groups were exposed to the CS for 3 or 10 min or an irrelevant tone (control stimulus, CtrS) for 10 min during SWS. The fourth group served as controls and was not subjected to any interventions. All of the subjects completed a memory test 4 h after SWS-rich stage to evaluate the effect on fear extinction. Moreover, we conducted similar experiments using an independent group of subjects during the daytime to test whether the memory extinction effect was specific to the sleep condition. Participants: Ninety-six healthy volunteers (44 males) aged 18–28 y. Measurements and Results: Participants exhibited undisturbed sleep during 2 consecutive nights, as assessed by sleep variables (all P > 0.05) from polysomnographic recordings and power spectral analysis. Participants who were re-exposed to the 10 min CS either during SWS and wakefulness exhibited attenuated fear responses (wake-10 min CS, P < 0.05; SWS-10 min CS, P < 0.01). Conclusions: Conditioned stimulus re-exposure during slow wave sleep promoted fear memory extinction without altering sleep profiles. Citation: He J, Sun HQ, Li SX, Zhang WH, Shi J, Ai SZ, Li Y, Li XJ, Tang XD, Lu L. Effect of conditioned stimulus exposure during slow wave sleep on fear memory extinction in humans. SLEEP 2015;38(3):423–431. PMID:25348121
Dymond, Simon; Rehfeldt, Ruth Anne
The transformation of stimulus functions is said to occur when the functions of one stimulus alter or transform the functions of another stimulus in accordance with the derived relation between the two, without additional training. This effect has been demonstrated with a number of derived stimulus relations, behavioral functions, experimental preparations, and subject populations. The present paper reviews much of the existing research on the transformation of stimulus functions and outlines a number of important methodological and conceptual issues that warrant further attention. We conclude by advocating the adoption of the generic terminology of relational frame theory to describe both the derived transformation of stimulus functions and relational responding more generally. PMID:22478349
Watanabe, Ryo; Kajimoto, Hiroyuki
We have previously found that a vertical force or tactile sensation occurs when the temperature of a participant’s skin changes rapidly. In this illusion, upward motion, pressure, or force sensation is elicited when stimulus temperature rises rapidly, whereas in the opposite case, downward motion or pulling sensation is elicited. In this paper, we applied this phenomenon to the sole (plantar surface of the foot) to present the sensation of ground slope. To investigate this, we conducted an experiment that measured the correlation between stimulation temperature and front–back direction position of the center of gravity. Participants stood on a thermal stimulator on Nintendo Wii Balance Board, and they remained standing during 30-s dynamic temperature stimulus. In result of analysis, it was suggested that dynamic thermal change in sole might influence standing position, and the effect pattern was anomalous in case of the participants who reported a swaying sensation without a haptic sensation. This behavior might be applied to the diagnosis of the presence of thermoesthesia of the patients who might have disease with absence of thermoesthesia. PMID:27917380
Hakala, Jussi; Kätsyri, Jari; Häkkinen, Jukka
Mediated facial expressions do not elicit emotions as strongly as real-life facial expressions, possibly due to the low fidelity of pictorial presentations in typical mediation technologies. In the present study, we investigated the extent to which stereoscopy amplifies emotions elicited by images of neutral, angry, and happy facial expressions. The emotional self-reports of positive and negative valence (which were evaluated separately) and arousal of 40 participants were recorded. The magnitude of perceived depth in the stereoscopic images was manipulated by varying the camera base at 15, 40, 65, 90, and 115 mm. The analyses controlled for participants' gender, gender match, emotional empathy, and trait alexithymia. The results indicated that stereoscopy significantly amplified the negative valence and arousal elicited by angry expressions at the most natural (65 mm) camera base, whereas stereoscopy amplified the positive valence elicited by happy expressions in both the narrowed and most natural (15-65 mm) base conditions. Overall, the results indicate that stereoscopy amplifies the emotions elicited by mediated emotional facial expressions when the depth geometry is close to natural. The findings highlight the sensitivity of the visual system to depth and its effect on emotions.
Kätsyri, Jari; Häkkinen, Jukka
Mediated facial expressions do not elicit emotions as strongly as real-life facial expressions, possibly due to the low fidelity of pictorial presentations in typical mediation technologies. In the present study, we investigated the extent to which stereoscopy amplifies emotions elicited by images of neutral, angry, and happy facial expressions. The emotional self-reports of positive and negative valence (which were evaluated separately) and arousal of 40 participants were recorded. The magnitude of perceived depth in the stereoscopic images was manipulated by varying the camera base at 15, 40, 65, 90, and 115 mm. The analyses controlled for participants’ gender, gender match, emotional empathy, and trait alexithymia. The results indicated that stereoscopy significantly amplified the negative valence and arousal elicited by angry expressions at the most natural (65 mm) camera base, whereas stereoscopy amplified the positive valence elicited by happy expressions in both the narrowed and most natural (15–65 mm) base conditions. Overall, the results indicate that stereoscopy amplifies the emotions elicited by mediated emotional facial expressions when the depth geometry is close to natural. The findings highlight the sensitivity of the visual system to depth and its effect on emotions. PMID:27551358
Haimson, Barry; Wilkinson, Krista M; Rosenquist, Celia; Ouimet, Carolyn; McIlvane, William J
Research reported here concerns neural processes relating to stimulus equivalence class formation. In Experiment 1, two types of word pairs were presented successively to normally capable adults. In one type, the words had related usage in English (e.g., uncle, aunt). In the other, the two words were not typically related in their usage (e.g., wrist, corn). For pairs of both types, event-related cortical potentials were recorded during and immediately after the presentation of the second word. The obtained waveforms differentiated these two types of pairs. For the unrelated pairs, the waveforms were significantly more negative about 400 ms after the second word was presented, thus replicating the “N400” phenomenon of the cognitive neuroscience literature. In addition, there was a strong positive-tending wave form difference post-stimulus presentation (peaked at about 500 ms) that also differentiated the unrelated from related stimulus pairs. In Experiment 2, the procedures were extended to study arbitrary stimulus–stimulus relations established via matching-to-sample training. Participants were experimentally naïve adults. Sample stimuli (Set A) were trigrams, and comparison stimuli (Sets B, C, D, E, and F) were nonrepresentative forms. Behavioral tests evaluated potentially emergent equivalence relations (i.e., BD, DF, CE, etc.). All participants exhibited classes consistent with the arbitrary matching training. They were also exposed also to an event-related potential procedure like that used in Experiment 1. Some received the ERP procedure before equivalence tests and some after. Only those participants who received ERP procedures after equivalence tests exhibited robust N400 differentiation initially. The positivity observed in Experiment 1 was absent for all participants. These results support speculations that equivalence tests may provide contextual support for the formation of equivalence classes including those that emerge gradually during testing
Takahashi, Kohske; Fukuda, Haruaki; Samejima, Kazuyuki; Watanabe, Katsumi; Ueda, Kazuhiro
In the uncanny valley phenomenon, the causes of the feeling of uncanniness as well as the impact of the uncanniness on behavioral performances still remain open. The present study investigated the behavioral effects of stimulus uncanniness, particularly with respect to speeded response. Pictures of fish were used as visual stimuli. Participants engaged in direction discrimination, spatial cueing, and dot-probe tasks. The results showed that pictures rated as strongly uncanny delayed speeded response in the discrimination of the direction of the fish. In the cueing experiment, where a fish served as a task-irrelevant and unpredictable cue for a peripheral target, we again observed that the detection of a target was slowed when the cue was an uncanny fish. Conversely, the dot-probe task suggested that uncanny fish, unlike threatening stimulus, did not capture visual spatial attention. These results suggested that stimulus uncanniness resulted in the delayed response, and importantly this modulation was not mediated by the feelings of threat. PMID:26052297
Galloway, W. D.
Experimental investigation upon pigeons of the relation between performance during discriminative training and subsequently obtained stimulus control test results. The results obtained support the proposition that bias generated by training dependencies is a major determiner of stimulus control.
Baliga, Chetana; Majhi, Sandipan; Mondal, Kajari; Bhattacharjee, Antara; Varadarajan, Raghavan
Cold-sensitive phenotypes have helped us understand macromolecular assembly and biological phenomena, yet few attempts have been made to understand the basis of cold sensitivity or to elicit it by design. We report a method for rational design of cold-sensitive phenotypes. The method involves generation of partial loss-of-function mutants, at either buried or functional sites, coupled with selective overexpression strategies. The only essential input is amino acid sequence, although available structural information can be used as well. The method has been used to elicit cold-sensitive mutants of a variety of proteins, both monomeric and dimeric, and in multiple organisms, namely Escherichia coli, Saccharomyces cerevisiae, and Drosophila melanogaster. This simple, yet effective technique of inducing cold sensitivity eliminates the need for complex mutations and provides a plausible molecular mechanism for eliciting cold-sensitive phenotypes. PMID:27091994
Kaufmann, Tobias; Kübler, Andrea
Objective. The speed of brain-computer interfaces (BCI), based on event-related potentials (ERP), is inherently limited by the commonly used one-stimulus paradigm. In this paper, we introduce a novel paradigm that can increase the spelling speed by a factor of 2, thereby extending the one-stimulus paradigm to a two-stimulus paradigm. Two different stimuli (a face and a symbol) are presented at the same time, superimposed on different characters and ERPs are classified using a multi-class classifier. Here, we present the proof-of-principle that is achieved with healthy participants. Approach. Eight participants were confronted with the novel two-stimulus paradigm and, for comparison, with two one-stimulus paradigms that used either one of the stimuli. Classification accuracies (percentage of correctly predicted letters) and elicited ERPs from the three paradigms were compared in a comprehensive offline analysis. Main results. The accuracies slightly decreased with the novel system compared to the established one-stimulus face paradigm. However, the use of two stimuli allowed for spelling at twice the maximum speed of the one-stimulus paradigms, and participants still achieved an average accuracy of 81.25%. This study introduced an alternative way of increasing the spelling speed in ERP-BCIs and illustrated that ERP-BCIs may not yet have reached their speed limit. Future research is needed in order to improve the reliability of the novel approach, as some participants displayed reduced accuracies. Furthermore, a comparison to the most recent BCI systems with individually adjusted, rapid stimulus timing is needed to draw conclusions about the practical relevance of the proposed paradigm. Significance. We introduced a novel two-stimulus paradigm that might be of high value for users who have reached the speed limit with the current one-stimulus ERP-BCI systems.
Paras, Carrie L; Webster, Michael A
The stimulus requirements for perceiving a face are not well defined but are presumably simple, for vivid faces can often by seen in random or natural images such as cloud or rock formations. To characterize these requirements, we measured where observers reported the impression of faces in images defined by symmetric 1/f noise. This allowed us to examine the prominence and properties of different features and their necessary configurations. In these stimuli many faces can be perceived along the vertical midline, and appear stacked at multiple scales, reminiscent of "totem poles." In addition to symmetry, the faces in noise are invariably upright and thus reveal the inversion effects that are thought to be a defining property of configural face processing. To a large extent, seeing a face required seeing eyes, and these were largely restricted to dark regions in the images. Other features were more subordinate and showed relatively little bias in polarity. Moreover, the prominence of eyes depended primarily on their luminance contrast and showed little influence of chromatic contrast. Notably, most faces were rated as clearly defined with highly distinctive attributes, suggesting that once an image area is coded as a face it is perceptually completed consistent with this interpretation. This suggests that the requisite trigger features are sufficient to holistically "capture" the surrounding noise structure to form the facial representation. Yet despite these well articulated percepts, we show in further experiments that while a pair of dark spots added to noise images appears face-like, these impressions fail to elicit other signatures of face processing, and in particular, fail to elicit an N170 or fixation patterns typical for images of actual faces. These results suggest that very simple stimulus configurations are sufficient to invoke many aspects of holistic and configural face perception while nevertheless failing to fully engage the neural machinery of face
Wronka, Eligiusz; Kaiser, Jan; Coenen, Anton M L
The aim of this study was the comparison of basic characteristics of the P3 subcomponents elicited in passive and active versions of the auditory oddball paradigm. A 3-stimulus oddball paradigm was employed in which subjects were presented with random sequence of tones while they performed a discrimination task in visual modality with no response to the tone (passive task) or responded to an infrequently occurring target stimulus inserted into sequence of frequent standard and rare non-target stimuli (active task). Results show that the magnitude of the frontal P3 response is determined by the relative perceptual distinctiveness among stimuli. The amplitude of frontal component is larger for the stimuli more deviated from the standard in both passive and active tasks. In all cases however, a maximum over central or fronto-central scalp regions was demonstrated. Moreover, amplitude of this component was influenced by the strength of attentional focus--a significantly larger response was obtained in the active session than in its passive counterpart. The apparent parietal P3 responses were obtained only in the active condition. The amplitude of this component is larger for the target than the non-target across all electrode sites, but both demonstrated a parietal maxima. This findings suggest that generation of early frontal P3 could be related to alerting activity of frontal cortex irrespective of stimulus context, while generation of later parietal P3 is related to temporo-parietal network activated when neuronal model of perceived stimulation and attentional trace are comparing.
Harm, Deborah L.; Zografos, Linda M.; Skinner, Noel C.; Parker, Donald E.
Compensatory vertical eye movement gain (CVEMG) was recorded during pitch oscillation in darkness before, during and immediately after exposures to the stimulus rearrangement produced by the Preflight Adaptation Trainer (PAT) Tilt-Translation Device (TTD). The TTD is designed to elicit adaptive responses that are similar to those observed in microgravity-adapted astronauts. The data from Experiment 1 yielded a statistically significant CVEMG decrease following 15 minutes of exposure to a stimulus rearrangement condition where the phase angle between subject pitch tilt and visual scene translation was 270 degrees; statistically significant gain decreases were not observed following exposures either to a condition where the phase angle between subject pitch and scene translation was 90 degrees or to a no-stimulus-rearrangement condition. Experiment 2 replicated the 270 degree phase condition from Experiment 1 and extended the exposure duration from 30 to 45 minutes. Statistically significant additional changes in CVEMG associated with the increased exposure duration were not observed. The adaptation time constant estimated from the combined data from Experiments 1 and 2 was 29 minutes.
Salisbury, Dean F
Deviations from repetitive auditory stimuli evoke a mismatch negativity (MMN). Counterintuitively, omissions of repetitive stimuli do not. Violations of patterns reflecting complex rules also evoke MMN. To detect a MMN to missing stimuli, we developed an auditory gestalt task using one stimulus. Groups of six pips (50 ms duration, 330 ms stimulus onset asynchrony [SOA], 400 trials), were presented with an intertrial interval (ITI) of 750 ms while subjects (n=16) watched a silent video. Occasional deviant groups had missing 4th or 6th tones (50 trials each). Missing stimuli evoked a MMN (p<.05). The missing 4th (-0.8 µV, p<.01) and the missing 6th stimuli (-1.1 µV, p<.05) were more negative than standard 6th stimuli (0.3 µV). MMN can be elicited by a missing stimulus at long SOAs by violation of a gestalt grouping rule. Patterned stimuli appear more sensitive to omissions and ITI than homogenous streams.
Naumann, E; Becker, G; Maier, S; Diedrich, O; Bartussek, D
The perception of the emotional content of a stimulus is a preattentive automatic process which causes an emotional reaction. As the ongoing stream of behavior might be disturbed by the emotional reaction, a controlled process is initialited at the same time, which normally leads to an inhibition of the emotional response. By means of event related potentials it should be possible to observe these controlled processes. In a first study using photographs from the International Affective Picture System, Diedrich et al. (1997) reported enhanded P300 amplitudes for emotional stimuli, even when the task distracted from the emotional content of the stimuli. This was interpreted as an index of the additional, controlled information processing elicited by the emotional content of the stimuli. Additionally, Diedrich et al. observed a frontel slow positivity, which might indicate the inhibition of the emotional response. However, this frontal slow wave might also be explained by the stimulus presentation time, which lasted 500 ms. This study is a conceptual replication of the experiment of Diedrich et al. Stimulus presentation time of neutral and emotional slides was varied in three steps (250 ms, 500 ms and 2000 ms). Subjects either performed a structural or an emotion-focused task on the stimuli. The results for the P300 component were exactly replicated. However, the variation of slow frontal positivity differed from that in the first study. Differences in the intensity of the emotional stimuli are discussed as a reason für this result.
Harm, Deborah L.; Zografos, Linda M.; Skinner, Noel C.; Parker, Donald E.
Compensatory vertical eye movement gain (CVEMG) was recorded during pitch oscillation in darkness before, during, and immediately after exposures to the stimulus rearrangement produced by the Preflight Adaptation Trainer (PAT) Tilt-Translation Device (TTD). The TTD is designed to elicit adaptive responses that are similar to those observed in microgravity-adapted astronauts. The data from Experiment 1 yielded a statistically significant CVEMG decrease following 15 min of exposure to a stimulus rearrangement condition where the phase angle between subject pitch tilt and visual scene translation was 270 deg; statistically significant gain decreases were not observed following exposures either to a condition where the phase angle between subject pitch and scene translation was 90 deg or to a no-stimulus-rearrangement condition. Experiment 2 replicated the 270-deg-phase condition from Experiment 1 and extended the exposure duration from 30 to 45 min. Statistically significant additional changes in CVEMG associated with the increased exposure duration were not observed. The adaptation time constant estimated fram the combined data from Experiments 1 and 2 was 29 min.
Mahoney, Jeannette R; Wang, Cuiling; Dumas, Kristina; Holtzer, Roee
Individuals are constantly bombarded by sensory stimuli across multiple modalities that must be integrated efficiently. Multisensory integration (MSI) is said to be governed by stimulus properties including space, time, and magnitude. While there is a paucity of research detailing MSI in aging, we have demonstrated that older adults reveal the greatest reaction time (RT) benefit when presented with simultaneous visual-somatosensory (VS) stimuli. To our knowledge, the differential RT benefit of visual and somatosensory stimuli presented within and across spatial hemifields has not been investigated in aging. Eighteen older adults (Mean = 74 years; 11 female), who were determined to be non-demented and without medical or psychiatric conditions that may affect their performance, participated in this study. Participants received eight randomly presented stimulus conditions (four unisensory and four multisensory) and were instructed to make speeded foot-pedal responses as soon as they detected any stimulation, regardless of stimulus type and location of unisensory inputs. Results from a linear mixed effect model, adjusted for speed of processing and other covariates, revealed that RTs to all multisensory pairings were significantly faster than those elicited to averaged constituent unisensory conditions (p < 0.01). Similarly, race model violation did not differ based on unisensory spatial location (p = 0.41). In summary, older adults demonstrate significant VS multisensory RT effects to stimuli both within and across spatial hemifields.
Fields, Lanny; Spear, Jack
Joint stimulus control occurs when responding is determined by the correspondence of elements of a complex sample and a complex comparison stimulus. In academic settings, joint stimulus control of behavior would be evidenced by the selection of an accurate description of a complex graph in which each element of a graph corresponded to particular…
Smith, S. A.; Querry, R. G.; Fadel, P. J.; Weiss, M. W.; Olivencia-Yurvati, A.; Shi, X.; Raven, P. B.
In order to characterize the stimulus-response relationships of the arterial, aortic, and carotid baroreflexes in mediating cardiac chronotropic function, we measured heart rate (HR) responses elicited by acute changes in mean arterial pressure (MAP) and carotid sinus pressure (CSP) in 11 healthy individuals. Arterial (aortic + carotid) baroreflex control of HR was quantified using ramped changes in MAP induced by bolus injection of phenylephrine (PE) and sodium nitroprusside (SN). To assess aortic-cardiac responses, neck pressure (NP) and suction (NS) were applied during PE and SN administration, respectively, to counter alterations in CSP thereby isolating the aortic baroreflex. Graded levels of NP and NS were delivered to the carotid sinus using a customized neck collar device to assess the carotid-cardiac baroreflex, independent of drug infusion. The operating characteristics of each reflex were determined from the logistic function of the elicited HR response to the induced change in MAP. The arterial pressures at which the threshold was located on the stimulus-response curves determined for the arterial, aortic and carotid baroreflexes were not significantly different (72+/-4, 67+/-3, and 72+/-4 mm Hg, respectively, P > 0.05). Similarly, the MAP at which the saturation of the reflex responses were elicited did not differ among the baroreflex arcs examined (98+/-3, 99+/-2, and 102+/-3 mm Hg, respectively). These data suggest that the baroreceptor populations studied operate over the same range of arterial pressures. This finding indicates each baroreflex functions as both an important anti-hypotensive and anti-hypertensive mechanism. In addition, this investigation describes a model of aortic baroreflex function in normal healthy humans, which may prove useful in identifying the origin of baroreflex dysfunction in disease- and training-induced conditions.
Brino, Ana Leda F.; Galvão, Olavo F.; Barros, Romariz S.; Goulart, Paulo R. K.; McIlvane, William J.
Teaching the first instances of arbitrary matching to sample to nonhumans can prove difficult and time consuming. Stimulus control relations may develop that differ from those intended by the experimenter – even when stimulus control shaping procedures are used. This paper reports efforts to identify sources of shaping program failure with a capuchin monkey. Procedures began with a baseline of identity matching. During subsequent shaping trials, compound comparison stimuli had two components – one identical to and another different from the sample. The identical component was eliminated gradually by removing portions across trials (i.e., subtracting stimulus elements). The monkey performed accurately throughout shaping. At a late stage in the program, probe tests were conducted: (1) arbitrary matching trials that had all elements of the identical comparison removed and (2) other trials that included residual elements. During the test, the monkey performed at low levels on the former trials and higher levels on the latter. These results suggested that higher accuracy was due merely to continued control by the residual elements: the target arbitrary matching relations had not been learned. Thus, it appears that procedures that gradually transform identity matching baselines into arbitrary matching can fail by inadvertently shaping restricted control by residual elements. Subsequent probes at the end of the shaping series showed a successful transfer of stimulus control from identity to arbitrary matching after further programming steps apparently overcame the restricted stimulus control. PMID:24817994
Brino, Ana Leda F; Barros, Romariz S; Galvão, Olavo F; Garotti, M; da Cruz, Ilara R. N; Santos, José R; Dube, William V; McIlvane, William J
This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys (Cebus apella). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The objective was to transform identity matching into arbitrary matching (i.e., matching not based on common physical features of the sample and comparison stimuli). Experiment 1 used a two-comparison procedure. The shaping procedure was ultimately effective, but occasional high error rates at certain program steps inspired a follow-up study. Experiment 2 used the same basic approach, but with a three-comparison matching task. During shaping, the monkey performed accurately until the final steps of the program. Subsequent experimentation tested the hypothesis that the decrease in accuracy was due to restricted stimulus control by sample stimulus features that had not yet been changed in the shaping program. Results were consistent with this hypothesis, thus suggesting a new approach that may transform the sample stimulus control shaping procedure from a sometimes useful laboratory tool to a more general approach to teaching the first instance of arbitrary matching performances to participants who show protracted difficulties in learning such performances. PMID:21547073
Brino, Ana Leda F; Barros, Romariz S; Galvão, Olavo F; Garotti, M; da Cruz, Ilara R N; Santos, José R; Dube, William V; McIlvane, William J
This paper reports use of sample stimulus control shaping procedures to teach arbitrary matching-to-sample to 2 capuchin monkeys (Cebus apella). The procedures started with identity matching-to-sample. During shaping, stimulus features of the sample were altered gradually, rendering samples and comparisons increasingly physically dissimilar. The objective was to transform identity matching into arbitrary matching (i.e., matching not based on common physical features of the sample and comparison stimuli). Experiment 1 used a two-comparison procedure. The shaping procedure was ultimately effective, but occasional high error rates at certain program steps inspired a follow-up study. Experiment 2 used the same basic approach, but with a three-comparison matching task. During shaping, the monkey performed accurately until the final steps of the program. Subsequent experimentation tested the hypothesis that the decrease in accuracy was due to restricted stimulus control by sample stimulus features that had not yet been changed in the shaping program. Results were consistent with this hypothesis, thus suggesting a new approach that may transform the sample stimulus control shaping procedure from a sometimes useful laboratory tool to a more general approach to teaching the first instance of arbitrary matching performances to participants who show protracted difficulties in learning such performances.
Preliminary results reveal that in some cells, the currents elicited by voltage steps are qualitatively similar to those previously described in frog ...rather than in the artificial perilymph used for the frog saccules. In some experiments individual hair cells were stimulated by moving their hair bundles...postsynaptic potentials alone. (2) Whole-cell current recording from isolated vestibular hair cells Hair cells were isolated from frog saccules and from rat
Bai, Yan; Yao, Zhong; Cong, Fengyu; Zhang, Linlin
There is an increasing interest regarding the use of electroencephalography (EEG) in social commerce and electronic commerce (e-commerce) research. There are several reviews in the field of social commerce or e-commerce; these have great potential value and mining them is fundamental and significant. To our knowledge, EEG is rarely applied to study these. In this study, we examined the neural correlates of social commerce reviews (SCRs) and e-commerce reviews (ECRs) by using them as stimuli to evoke event-related potentials. All SCRs were from friends through a social media platform, whereas ECRs were from strangers through an e-commerce platform. The experimental design was similar to that of a priming paradigm, and included 40 pairs of stimuli consisting of product information (prime stimulus) and reviews (target stimulus). The results showed that the P300 component was successfully evoked by SCR and ECR stimuli. Moreover, the P300 components elicited by SCRs had higher amplitudes than those elicited by ECRs. These findings indicate that participants paid more attention to SCRs than to ECRs. In addition, the associations between neural responses and reviews in social commerce have the potential to assist companies in studying consumer behaviors, thus permitting them to enhance their social commerce strategies.
Frey, Johannes Daniel; Wendt, Mike; Löw, Andreas; Möller, Stephan; Zölzer, Udo; Jacobsen, Thomas
Changes in room acoustics provide important clues about the environment of sound source-perceiver systems, for example, by indicating changes in the reflecting characteristics of surrounding objects. To study the detection of auditory irregularities brought about by a change in room acoustics, a passive oddball protocol with participants watching a movie was applied in this study. Acoustic stimuli were presented via headphones. Standards and deviants were created by modelling rooms of different sizes, keeping the values of the basic acoustic dimensions (e.g., frequency, duration, sound pressure, and sound source location) as constant as possible. In the first experiment, each standard and deviant stimulus consisted of sequences of three short sounds derived from sinusoidal tones, resulting in three onsets during each stimulus. Deviant stimuli elicited a Mismatch Negativity (MMN) as well as two additional negative deflections corresponding to the three onset peaks. In the second experiment, only one sound was used; the stimuli were otherwise identical to the ones used in the first experiment. Again, an MMN was observed, followed by an additional negative deflection. These results provide further support for the hypothesis of automatic detection of unattended changes in room acoustics, extending previous work by demonstrating the elicitation of an MMN by changes in room acoustics.
Itzhak Perlman) or a concertmeister in an orchestra, or simply one of its violinists . Differences in amount of expertise may supply different...would lead to becoming a world class violinist . Underlying Assumptions In attempting to elicit information from experts, one makes a number of
Doruk, Bekir Kürsat
Researchers have proposed a variety of methods to make a connection between real life and mathematics so that it can be learned in a practical way and enable people to utilise mathematics in their daily lives. Model-eliciting activities (MEAs) were developed to fulfil this need and are very capable of serving this purpose. The reason MEAs are so…
Gonzales, Carol Kernitzki
Many software development projects fail because they do not meet the needs of users, are over-budget, and abandoned. To address this problem, the user requirements elicitation process was modified based on principles of Appreciative Inquiry. Appreciative Inquiry, commonly used in organizational development, aims to build organizations, processes,…
Illustrates the power of video recording to elicit the thinking of teachers as they reflect on their teaching practices. Draws on the work of Wiley (1994), which identified the internal conversation as a critical feature of the semiotic self. (Author/VWL)
Barutchu, Ayla; Freestone, Dean R; Innes-Brown, Hamish; Crewther, David P; Crewther, Sheila G
Currently debate exists relating to the interplay between multisensory processes and bottom-up and top-down influences. However, few studies have looked at neural responses to newly paired audiovisual stimuli that differ in their prescribed relevance. For such newly associated audiovisual stimuli, optimal facilitation of motor actions was observed only when both components of the audiovisual stimuli were targets. Relevant auditory stimuli were found to significantly increase the amplitudes of the event-related potentials at the occipital pole during the first 100 ms post-stimulus onset, though this early integration was not predictive of multisensory facilitation. Activity related to multisensory behavioral facilitation was observed approximately 166 ms post-stimulus, at left central and occipital sites. Furthermore, optimal multisensory facilitation was found to be associated with a latency shift of induced oscillations in the beta range (14-30 Hz) at right hemisphere parietal scalp regions. These findings demonstrate the importance of stimulus relevance to multisensory processing by providing the first evidence that the neural processes underlying multisensory integration are modulated by the relevance of the stimuli being combined. We also provide evidence that such facilitation may be mediated by changes in neural synchronization in occipital and centro-parietal neural populations at early and late stages of neural processing that coincided with stimulus selection, and the preparation and initiation of motor action.
Mühlberger, Christina; Angus, Douglas Jozef; Jonas, Eva; Harmon-Jones, Cindy; Harmon-Jones, Eddie
The reward positivity (RewP) and the stimulus preceding negativity (SPN), two ERPs associated with reward delivery and reward anticipation, are modulated by motivational intensity. Motivational intensity is the effort organisms would make to exert behaviors, and it varies with the difficulty of exerting that behavior. If a task is perceived as impossible, which means that one does not have control over own outcomes, motivational intensity is low. In the current study, we tested the prediction that perceiving control over one's outcomes increases both the RewP to feedback and the SPN prior to feedback compared to perceiving no control. We also examined whether P300 and LPP amplitudes to reward and nonreward images were similarly modulated. Twenty-five female participants completed a gambling task in which correct choices were followed by pictures of attractive men and incorrect choices were followed by pictures of rocks. To manipulate perceived control, participants were told that, in one block of trials, they could learn a mouse-click rule in order to see only pictures of men (high perceived control condition), while in the other block, the pictures would appear randomly (low perceived control condition). However, in both conditions, feedback appeared randomly. Although the RewP was elicited in both blocks, the RewP and SPN were higher in the high perceived control condition (i.e., when participants thought that they could influence their outcomes). Perceived control did not modulate the P300 and LPP to pictures. The results suggest that approach motivation and its intensity modulate the processing of performance feedback.
Ng, Kian B.; Bradley, Andrew P.; Cunnington, Ross
The mechanisms of neural excitation and inhibition when given a visual stimulus are well studied. It has been established that changing stimulus specificity such as luminance contrast or spatial frequency can alter the neuronal activity and thus modulate the visual-evoked response. In this paper, we study the effect that stimulus specificity has on the classification performance of a steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI). For example, we investigate how closely two visual stimuli can be placed before they compete for neural representation in the cortex and thus influence BCI classification accuracy. We characterize stimulus specificity using the four stimulus parameters commonly encountered in SSVEP-BCI design: temporal frequency, spatial size, number of simultaneously displayed stimuli and their spatial proximity. By varying these quantities and measuring the SSVEP-BCI classification accuracy, we are able to determine the parameters that provide optimal performance. Our results show that superior SSVEP-BCI accuracy is attained when stimuli are placed spatially more than 5° apart, with size that subtends at least 2° of visual angle, when using a tagging frequency of between high alpha and beta band. These findings may assist in deciding the stimulus parameters for optimal SSVEP-BCI design.
Ng, Kian B; Bradley, Andrew P; Cunnington, Ross
The mechanisms of neural excitation and inhibition when given a visual stimulus are well studied. It has been established that changing stimulus specificity such as luminance contrast or spatial frequency can alter the neuronal activity and thus modulate the visual-evoked response. In this paper, we study the effect that stimulus specificity has on the classification performance of a steady-state visual-evoked potential-based brain-computer interface (SSVEP-BCI). For example, we investigate how closely two visual stimuli can be placed before they compete for neural representation in the cortex and thus influence BCI classification accuracy. We characterize stimulus specificity using the four stimulus parameters commonly encountered in SSVEP-BCI design: temporal frequency, spatial size, number of simultaneously displayed stimuli and their spatial proximity. By varying these quantities and measuring the SSVEP-BCI classification accuracy, we are able to determine the parameters that provide optimal performance. Our results show that superior SSVEP-BCI accuracy is attained when stimuli are placed spatially more than 5° apart, with size that subtends at least 2° of visual angle, when using a tagging frequency of between high alpha and beta band. These findings may assist in deciding the stimulus parameters for optimal SSVEP-BCI design.
Wessel, Jan R; O'Doherty, John P; Berkebile, Michael M; Linderman, David; Aron, Adam R
Impulsive behavior in humans partly relates to inappropriate overvaluation of reward-associated stimuli. Hence, it is desirable to develop methods of behavioral modification that can reduce stimulus value. Here, we tested whether one kind of behavioral modification--the rapid stopping of actions in the face of reward-associated stimuli--could lead to subsequent devaluation of those stimuli. We developed a novel paradigm with three consecutive phases: implicit reward learning, a stop-signal task, and an auction procedure. In the learning phase, we associated abstract shapes with different levels of reward. In the stop-signal phase, we paired half those shapes with occasional stop-signals, requiring the rapid stopping of an initiated motor response, while the other half of shapes was not paired with stop signals. In the auction phase, we assessed the subjective value of each shape via willingness-to-pay. In 2 experiments, we found that participants bid less for shapes that were paired with stop-signals compared to shapes that were not. This suggests that the requirement to try to rapidly stop a response decrements stimulus value. Two follow-on control experiments suggested that the result was specifically due to stopping action rather than aversiveness, effort, conflict, or salience associated with stop signals. This study makes a theoretical link between research on inhibitory control and value. It also provides a novel behavioral paradigm with carefully operationalized learning, treatment, and valuation phases. This framework lends itself to both behavioral modification procedures in clinical disorders and research on the neural underpinnings of stimulus devaluation.
Scheithauer, Mindy C; Tiger, Jeffrey H
Line tracking is a prerequisite skill for braille literacy that involves moving one's finger horizontally across a line of braille text and identifying when a line ends so the reader may reset his or her finger on the subsequent line. Current procedures for teaching line tracking are incomplete, because they focus on tracking lines with only small gaps between characters. The current study extended previous line-tracking instruction using stimulus fading to teach tracking across larger gaps. After instruction, all participants showed improvement in line tracking, and 2 of 3 participants met mastery criteria for tracking across extended spaces.
provide broader support for the economy than monetary policy actions alone.” Quoted in Ben Bernanke , “The Economic Outlook,” testimony before the House...limit for mortgages from $417,000 up to $729,750 in high-cost areas. The need for fiscal stimulus depends, by definition, on the state of the economy ...While the economy is not officially in a recession at present, there are signs that economic activity may be slowing. Some economists are predicting
McIlvane, William J.; Dube, William V.
Stimulus control topography refers to qualitative differences among members of a functional stimulus class. Stimulus control topography coherence refers to the degree of concordance between the stimulus properties specified as relevant by the individual arranging a reinforcement contingency (behavior analyst, experimenter, teacher, etc.) and the stimulus properties that come to control the behavior of the organism (experimental subject, student, etc.) that experiences those contingencies. This paper summarizes the rationale for analyses of discrimination learning outcomes in terms of stimulus control topography coherence and briefly reviews some of the foundational studies that led to this perspective. We also suggest directions for future research, including pursuit of conceptual and methodological challenges to a complete stimulus control topography coherence analysis of processes involved in discriminated and generalized operants. ImagesFigure 3Figure 5 PMID:22478402
Dawes, C; O'Connor, A M; Aspen, J M
In the first study, whole saliva was collected from ten adults during stimulation with sour, carbonated, sweet and water stimuli in the form of 5-ml of ice at about -10 degrees C or of liquids at 0, 8, 20 or 37 degrees C. Parotid saliva was also collected in response to ice or infusion into the mouth of the liquids at different temperatures. Another group of ten adults also collected whole saliva in response to water at 20 degrees C, with or without the presence in the mouth of an acrylic cube of dimensions similar to those of the ice. In a second study, 20 adults collected whole saliva in response to stimulation with 5 ml of water and of an astringent stimulus at 0, 8, 37 and 70 degrees C. In the first study, flow rates fell in the order sour, carbonated, sweet and water and flow rates in response to stimuli in the form of ice were very significantly higher than in response to the corresponding liquids at the four different temperatures. With the sour stimulus, liquids at 0 and 8 degrees C elicited higher flow rates than liquids at 20 or 37 degrees C. Although the presence in the mouth of the acrylic block increased the flow rate of whole saliva, the increase was only about 30% of that achieved with ice. In the second study, the astringent stimulus was a more effective salivary stimulus than water; flow rates were significantly higher in response to liquids at 0 and 8 degrees C than at the higher temperatures and flow rates in response to liquids at 37 degrees C were significantly lower than with the other temperatures. In summary, stimuli in the form of ice were the most effective and liquids at 37 degrees C were least effective in stimulating salivary flow.
Ferrey, Anne E; Burleigh, Tyler J; Fenske, Mark J
Stimuli that resemble humans, but are not perfectly human-like, are disliked compared to distinctly human and non-human stimuli. Accounts of this "Uncanny Valley" effect often focus on how changes in human resemblance can evoke different emotional responses. We present an alternate account based on the novel hypothesis that the Uncanny Valley is not directly related to 'human-likeness' per se, but instead reflects a more general form of stimulus devaluation that occurs when inhibition is triggered to resolve conflict between competing stimulus-related representations. We consider existing support for this inhibitory-devaluation hypothesis and further assess its feasibility through tests of two corresponding predictions that arise from the link between conflict-resolving inhibition and aversive response: (1) that the pronounced disliking of Uncanny-type stimuli will occur for any image that strongly activates multiple competing stimulus representations, even in the absence of any human-likeness, and (2) that the negative peak of an 'Uncanny Valley' should occur at the point of greatest stimulus-related conflict and not (in the presence of human-likeness) always closer to the 'human' end of a perceptual continuum. We measured affective responses to a set of line drawings representing non-human animal-animal morphs, in which each continuum midpoint was a bistable image (Experiment 1), as well as to sets of human-robot and human-animal computer-generated morphs (Experiment 2). Affective trends depicting classic Uncanny Valley functions occurred for all continua, including the non-human stimuli. Images at continua midpoints elicited significantly more negative affect than images at endpoints, even when the continua included a human endpoint. This illustrates the feasibility of the inhibitory-devaluation hypothesis and the need for further research into the possibility that the strong dislike of Uncanny-type stimuli reflects the negative affective consequences of
Ferrey, Anne E.; Burleigh, Tyler J.; Fenske, Mark J.
Stimuli that resemble humans, but are not perfectly human-like, are disliked compared to distinctly human and non-human stimuli. Accounts of this “Uncanny Valley” effect often focus on how changes in human resemblance can evoke different emotional responses. We present an alternate account based on the novel hypothesis that the Uncanny Valley is not directly related to ‘human-likeness’ per se, but instead reflects a more general form of stimulus devaluation that occurs when inhibition is triggered to resolve conflict between competing stimulus-related representations. We consider existing support for this inhibitory-devaluation hypothesis and further assess its feasibility through tests of two corresponding predictions that arise from the link between conflict-resolving inhibition and aversive response: (1) that the pronounced disliking of Uncanny-type stimuli will occur for any image that strongly activates multiple competing stimulus representations, even in the absence of any human-likeness, and (2) that the negative peak of an ‘Uncanny Valley’ should occur at the point of greatest stimulus-related conflict and not (in the presence of human-likeness) always closer to the ‘human’ end of a perceptual continuum. We measured affective responses to a set of line drawings representing non-human animal–animal morphs, in which each continuum midpoint was a bistable image (Experiment 1), as well as to sets of human-robot and human-animal computer-generated morphs (Experiment 2). Affective trends depicting classic Uncanny Valley functions occurred for all continua, including the non-human stimuli. Images at continua midpoints elicited significantly more negative affect than images at endpoints, even when the continua included a human endpoint. This illustrates the feasibility of the inhibitory-devaluation hypothesis and the need for further research into the possibility that the strong dislike of Uncanny-type stimuli reflects the negative affective
Chaudhry, Hera; Fatima, Nida; Ahmad, Iffat Zareen
Nigella sativa L. (family Ranunculaceae) is an annual herb of immense medicinal properties because of its major active components (i.e., thymoquinone (TQ), thymohydroquinone (THQ), and thymol (THY)). Plant tissue culture techniques like elicitation, Agrobacterium mediated transformation, hairy root culture, and so on, are applied for substantial metabolite production. This study enumerates the antibacterial and antioxidant potentials of N. sativa epicotyl suspension cultures under biotic and abiotic elicitation along with concentration optimization of the elicitors for enhanced TQ and THY production. Cultures under different concentrations of pectin and manganese chloride (MnCl2) elicitation (i.e., 5 mg/L, 10 mg/L, and 15 mg/L) showed that the control, MnCl2 10 mg/L, and pectin 15 mg/L suspension extracts greatly inhibited the growth of E. coli, S. typhimurium, and S. aureus (MIC against E. coli, i.e., 2.35 ± 0.8, 2.4 ± 0.2, and 2.46 ± 0.5, resp.). Elicitation decreased SOD enzyme activity whereas CAT enzyme activity increased remarkably under MnCl2 elicitation. MnCl2 10 mg/L and pectin 15 mg/L elicitation enhanced the DPPH radical inhibition ability, but ferric scavenging activity was comparable to the control. TQ and THY were quantified by LC-MS/MS in the cultures with high bioactive properties revealing maximum content under MnCl2 10 mg/L elicitation. Therefore, MnCl2 elicitation can be undertaken on large scale for sustainable metabolite production. PMID:26347883
Carstens, E; Wilson, C
1. To quantitatively investigate a nocifensive behavioral response, we developed a method to measure the magnitude of the rat's tail flick reflex and its modulation. A radial array of force transducers measured forces of tail flicks (in rostral, horizontal, and vertical planes) elicited by graded noxious radiant thermal stimulation of the conscious rat's tail, from which the overall movement vector was calculated. 2. The rostrally directed component of tail flicks was always larger than dorsal or horizontal components; the latter was usually in a preferred (left or right) direction regardless of which side of the tail was heated. Tail flick force vectors increased from 40 to 46-52 degrees C and then leveled off. Stimulus-response functions were reproducible within and across rats and were fitted by second-order polynomial functions, whose correlation coefficients were similar when the left or right side of the tail was stimulated in separate sessions (r2 = 0.408 and 0.451, respectively). The inverse latency of tail flicks also increased with temperature in a manner fitted by a second-order polynomial (r2 = 0.707, 0.553 for left and right side, respectively). 3. Systemic administration of morphine (1 or 2 mg/kg ip) usually suppressed tail flicks in an all-or-none manner; i.e., flicks at all stimulus temperatures were either totally abolished (n = 7) or unaffected (n = 5) after morphine. In three rats, 1 mg/kg morphine suppressed tail flick magnitude subtotally, reducing the slope of the linear portion of the stimulus-response function. Morphine effects were reversed by the opiate antagonist naloxone. 4. Tail flick magnitude decreased over repeated trials of 44 degrees C heat stimuli delivered to one tail site, recovered after a 15-min rest period, and decremented more quickly with subsequent stimulus repetition. The decrement was less at long (2 or 4 min) than at short (1 min) interstimulus intervals, and high (50 degrees C) than at low (44 degrees C) stimulus
Stevenson, Ryan A.; Wallace, Mark T.
The ability of human sensory systems to integrate information across the different modalities provides a wide range of behavioral and perceptual benefits. This integration process is dependent upon the temporal relationship of the different sensory signals, with stimuli occurring close together in time typically resulting in the largest behavior changes. The range of temporal intervals over which such benefits are seen is typically referred to as the temporal binding window (TBW). Given the importance of temporal factors in multisensory integration under both normal and atypical circumstances such as autism and dyslexia, the TBW has been measured with a variety of experimental protocols that differ according to criterion, task, and stimulus type, making comparisons across experiments difficult. In the current study we attempt to elucidate the role that these various factors play in the measurement of this important construct. The results show a strong effect of stimulus type, with the TBW assessed with speech stimuli being both larger and more symmetrical than that seen using simple and complex non-speech stimuli. These effects are robust across task and statistical criteria, and are highly consistent within individuals, suggesting substantial overlap in the neural and cognitive operations that govern multisensory temporal processes. PMID:23604624
Grieve, R; Parker, P A; Hudgins, B; Englehart, K
Noninvasive measurements of somatosensory evoked potentials have both clinical and research applications. The electrical artifact which results from the stimulus is an interference which can distort the evoked signal, and introduce errors in response onset timing estimation. Given that this interference is synchronous with the evoked signal, it cannot be reduced by the conventional technique of ensemble averaging. The technique of adaptive noise cancelling has potential in this regard however, and has been used effectively in other similar problems. An adaptive noise cancelling filter which uses a neural network as the adaptive element is investigated in this application. The filter is implemented and performance determined in the cancelling of artifact for in vivo measurements on the median nerve. A technique of segmented neural network training is proposed in which the network is trained on that segment of the record time window which does not contain the evoked signal. The neural network is found to generalize well from this training to include the segment of the window containing the evoked signal. Both quantitative and qualitative measures show that significant stimulus artifact reduction is achieved.
Nomata, Takuya; Okuyama, Takeshi; Teraoka, Hiromi; Murakami, Yasuo; Miyazawa, Kiyoshi; Tanaka, Mami
This paper describes a development of a sensor system for measurement of a contact stimulus which diapers give to infants. A polyvinyliden fluoride (PVDF) film and a strain gauge are used as the sensor receptors. The PVDF is a kind of piezoelectric material. The sensor consists of a surface contact layer, a PVDF film, a strain gauge and an aluminum plate. First, in order to investigate the sensor performance, the sensor was located on a silicone plate and the upper part of the sensor was rubbed with an acrylic artificial finger. The finger enabled the measurement to carry out at a constant speed and force. Next, the sensor was attached on an infant dummy and the sensor outputs were measured under conditions with and without diapers. By comparison of the output under two different conditions, it was confirmed that there is a clearly difference between the two conditions. It was found that the developed sensor system has the possibility to quantify a contact stimulus which diapers give infants.
Nomata, Takuya; Okuyama, Takeshi; Teraoka, Hiromi; Murakami, Yasuo; Miyazawa, Kiyoshi; Tanaka, Mami
This paper describes a development of a sensor system for measurement of a contact stimulus which diapers give to infants. A polyvinyliden fluoride (PVDF) film and a strain gauge are used as the sensor receptors. The PVDF is a kind of piezoelectric material. The sensor consists of a surface contact layer, a PVDF film, a strain gauge and an aluminum plate. First, in order to investigate the sensor performance, the sensor was located on a silicone plate and the upper part of the sensor was rubbed with an acrylic artificial finger. The finger enabled the measurement to carry out at a constant speed and force. Next, the sensor was attached on an infant dummy and the sensor outputs were measured under conditions with and without diapers. By comparison of the output under two different conditions, it was confirmed that there is a clearly difference between the two conditions. It was found that the developed sensor system has the possibility to quantify a contact stimulus which diapers give infants.
Anes, Laura; Obi, Marianne
A serious illness, a chronic medical condition or a hospital bed should not deny any child her/his basic right to play, a right essential for children's development and general wellbeing. In fact, it is in these frightening and anxious moments that play and the stimulus that it provides can help the most. This article will focus on the impacts and benefits of professional hospital clowning for the wellbeing and recovery process of ill and hospitalized children. Our experience has shown that through interactive play and humor, "clowndoctors" can create an enabling and supportive environment that facilitates children's adaptation to the hospital setting and improves their acceptance of medical procedures and staff. While moving from bedside to bedside, RED NOSES clowndoctors encourage children's active participation and support their natural instinct to play, fully including them in the interaction, if the children wish to do so. Therefore, clowndoctor performances offer ill children much needed stimulus, self-confidence and courage, elements fundamental to reducing their vulnerability. In this piece, a special emphasis will be put on the various approaches used by RED NOSES clowndoctors to bond and reach out to children suffering from different medical conditions.
Anes, Laura; Obi, Marianne
A serious illness, a chronic medical condition or a hospital bed should not deny any child her/his basic right to play, a right essential for children’s development and general wellbeing. In fact, it is in these frightening and anxious moments that play and the stimulus that it provides can help the most. This article will focus on the impacts and benefits of professional hospital clowning for the wellbeing and recovery process of ill and hospitalized children. Our experience has shown that through interactive play and humor, “clowndoctors” can create an enabling and supportive environment that facilitates children’s adaptation to the hospital setting and improves their acceptance of medical procedures and staff. While moving from bedside to bedside, RED NOSES clowndoctors encourage children’s active participation and support their natural instinct to play, fully including them in the interaction, if the children wish to do so. Therefore, clowndoctor performances offer ill children much needed stimulus, self-confidence and courage, elements fundamental to reducing their vulnerability. In this piece, a special emphasis will be put on the various approaches used by RED NOSES clowndoctors to bond and reach out to children suffering from different medical conditions. PMID:27417485
Hanna, Elenice S.; Blackman, Derek E.; Todorov, João Claudio
Six experimentally naive pigeons were exposed to concurrent variable-interval variable-interval schedules in a three-key procedure in which food reinforcement followed pecks on the side keys and pecks on the center key served as changeover responses. In Phase 1, 3 birds were exposed to 20 combinations of five variable-interval values, with each variable-interval value consistently associated with a different color on the side keys. Another 3 pigeons were exposed to the same 20 conditions, but with a more standard procedure that used a nondifferential discriminative stimulus on the two side keys throughout all conditions. In Phase 2, the differential and nondifferential stimulus conditions were reversed for each pigeon. Each condition lasted for one 5-hr session and one subsequent 1-hr session. In the last 14 conditions of each phase, the presence of differential discriminative stimuli decreased the time necessary for differential responding to develop and increased the sensitivity of behavior to reinforcement distribution in the 1st hr of training; during the last hours of training in each condition, however, the effects of the differential discriminative stimuli could not be distinguished from the effects of reinforcement distribution per se. These results show the importance of studying transitions in behavior as well as final performance. They may also be relevant to discrepancies in the results of previous experiments that have used nonhuman and human subjects. PMID:16812669
Kam, Xuân-Nga Cao; Stoyneshka, Iglika; Tornyova, Lidiya; Fodor, Janet D; Sakas, William G
Recent challenges to Chomsky's poverty of the stimulus thesis for language acquisition suggest that children's primary data may carry "indirect evidence" about linguistic constructions despite containing no instances of them. Indirect evidence is claimed to suffice for grammar acquisition, without need for innate knowledge. This article reports experiments based on those of Reali and Christiansen (2005), who demonstrated that a simple bigram language model can induce the correct form of auxiliary inversion in certain complex questions. This article investigates the nature of the indirect evidence that supports this learning, and assesses how reliably it is available. Results confirm the original finding for one specific sentence type but show that the model's success is highly circumscribed. It performs poorly on inversion in related constructions in English and Dutch. Because other, more powerful statistical models have so far been shown to succeed only on the same limited subset of cases as the bigram model, it remains to be seen whether stimulus richness can be substantiated more generally.
Morgan, M. G.
Since the early 1990's the author has been involved in the design and execution of six detailed expert elicitations that, among other things, have obtained subjective judgments from experts that reflect their best judgment in the form of subjective probability density functions, about the value of key climate variables, climate impacts and a technology for mitigation (Morgan and Keith, 1995; Morgan Pitelka and Shevliakova, 2001; Morgan, Adams and Keith, 2006; Zickfeld et al, 2007; Curtright, Morgan and Keith, 2008; Zickfeld, Morgan Keith and Frame, in review). This paper builds on that experience to draw insights about the design and use of expert elicitation in the assessment and analysis of climate change and its impacts. Several trends in responses will be noted. Methodological pitfalls will be discussed. Comparisons will be drawn with the consensus-based methods employed by IPCC, which appear to have produced tighter uncertainty bounds than individual elicitation. The paper will close with thoughts on the possible use of expert elicitation in future IPCC assessments. Support for this work is from the Climate Decision Making Center through a cooperative agreement between the National Science Foundation (SES-0345798) and Carnegie Mellon University. References: M. Granger Morgan and David Keith, "Subjective Judgments by Climate Experts," Environmental Science & Technology, 29(10), 468A-476A, October 1995. M. Granger Morgan, Louis F. Pitelka and Elena Shevliakova, "Elicitation of Expert Judgments of Climate Change Impacts on Forest Ecosystems," Climatic Change, 49, 279-307, 2001. M. Granger Morgan, Peter Adams, and David W. Keith, "Elicitation of Expert Judgments of Aerosol Forcing," Climatic Change, 75, 195-214, 2006. Kirsten Zickfeld, Anders Levermann, Till Kuhlbrodt. Stefan Rahmstorf, M. Granger Morgan and David Keith, "Expert Judgements on the Response on the Atlantic Meridional Overturning Circulation to Climate Change," Climatic Change, 82, 235-265, 2007
Kinloch, Jennifer May; McEwan, James Stewart Anderson; Foster, T. Mary
Studies comparing the effectiveness of the stimulus-pairing-observation and matching-to-sample procedures in facilitating equivalence relations have reported conflicting findings. This study compared the effectiveness of these procedures and examined the effect of stimulus arrangement and the number of training trials completed prior to each…
Zhang, Honghui; Wang, Qingyun; Chen, Guanrong
Experimental studies have shown that neuron population located in the basal ganglia of parkinsonian primates can exhibit characteristic firings with certain firing rates differing from normal brain activities. Motivated by recent experimental findings, we investigate the effects of various stimulation paradigms on the firing rates of parkinsonism based on the proposed dynamical models. Our results show that the closed-loop deep brain stimulation is superior in ameliorating the firing behaviors of the parkinsonism, and other control strategies have similar effects according to the observation of electrophysiological experiments. In addition, in conformity to physiological experiments, we found that there exists optimal delay of input in the closed-loop GPtrain|M1 paradigm, where more normal behaviors can be obtained. More interestingly, we observed that W-shaped curves of the firing rates always appear as stimulus delay varies. We furthermore verify the robustness of the obtained results by studying three pallidal discharge rates of the parkinsonism based on the conductance-based model, as well as the integrate-and-fire-or-burst model. Finally, we show that short-term plasticity can improve the firing rates and optimize the control effects on parkinsonism. Our conclusions may give more theoretical insight into Parkinson's disease studies.
Calore, Enrico; Gadia, Davide; Marini, Daniele
Brain-Computer Interfaces (BCIs) provide users communication and control capabilities by analyzing their brain activity. A technique to implement BCIs, used recently also in Virtual Reality (VR) environments, is based on the Steady State Visual Evoked Potentials (SSVEPs) detection. Exploiting the SSVEP response, BCIs could be implemented showing targets flickering at different frequencies and detecting which is gazed by the observer analyzing her/his electroencephalographic (EEG) signals. In this work, we evaluate the use of stereoscopic displays for the presentation of SSVEP eliciting stimuli, comparing their effectiveness between monoscopic and stereoscopic stimuli. Moreover we propose a novel method to elicit SSVEP responses exploiting the stereoscopic displays capability of presenting dichoptic stimuli. We have created an experimental scene to present flickering stimuli on an active stereoscopic display, obtaining reliable control of the targets' frequency independently for the two stereo views. Using an EEG acquisition device, we analyzed the SSVEP responses from a group of subjects. From the preliminary results, we got evidence that stereoscopic displays represent valid devices for the presentation of SSVEP stimuli. Moreover, the use of different flickering frequencies for the two views of a single stimulus proved to elicit non-linear interactions between the stimulation frequencies, clearly visible in the EEG signal. This suggests interesting applications for SSVEP-based BCIs in VR environments able to overcome some limitations imposed by the refresh frequency of standard displays, but also the use of commodity stereoscopic displays to implement binocular rivalry experiments.
Tu, Yiheng; Tan, Ao; Bai, Yanru; Hung, Yeung Sam; Zhang, Zhiguo
Pain is a highly subjective experience. Self-report is the gold standard for pain assessment in clinical practice, but it may not be available or reliable in some populations. Neuroimaging data, such as electroencephalography (EEG) and functional magnetic resonance imaging (fMRI), have the potential to be used to provide physiology-based and quantitative nociceptive pain assessment tools that complements self-report. However, existing neuroimaging-based nociceptive pain assessments only rely on the information in pain-evoked brain activities, but neglect the fact that the perceived intensity of pain is also encoded by ongoing brain activities prior to painful stimulation. Here, we proposed to use machine learning algorithms to decode pain intensity from both pre-stimulus ongoing and post-stimulus evoked brain activities. Neural features that were correlated with intensity of laser-evoked nociceptive pain were extracted from high-dimensional pre- and post-stimulus EEG and fMRI activities using partial least-squares regression (PLSR). Further, we used support vector machine (SVM) to predict the intensity of pain from pain-related time-frequency EEG patterns and BOLD-fMRI patterns. Results showed that combining predictive information in pre- and post-stimulus brain activities can achieve significantly better performance in classifying high-pain and low-pain and in predicting the rating of perceived pain than only using post-stimulus brain activities. Therefore, the proposed pain prediction method holds great potential in basic research and clinical applications. PMID:27148029
Abdelmohsen, Usama Ramadan; Grkovic, Tanja; Balasubramanian, Srikkanth; Kamel, Mohamed Salah; Quinn, Ronald J; Hentschel, Ute
Genomic sequence data have revealed the presence of a large fraction of putatively silent biosynthetic gene clusters in the genomes of actinomycetes that encode for secondary metabolites, which are not detected under standard fermentation conditions. This review focuses on the effects of biological (co-cultivation), chemical, as well as molecular elicitation on secondary metabolism in actinomycetes. Our review covers the literature until June 2014 and exemplifies the diversity of natural products that have been recovered by such approaches from the phylum Actinobacteria.
Firmino, Paulo Renato A.; dos Santos Neto, Ademir B.
In probability elicitation exercises it has been usual to considerer scoring rules (SRs) to measure the performance of experts when inferring about a given unknown, Θ, for which the true value, θ*, is (or will shortly be) known to the experimenter. Mathematically, SRs quantify the discrepancy between f(θ) (the distribution reflecting the expert's uncertainty about Θ) and d(θ), a zero-one indicator function of the observation θ*. Thus, a remarkable characteristic of SRs is to contrast expert's beliefs with the observation θ*. The present work aims at extending SRs concepts and formulas for the cases where Θ is aleatory, highlighting advantages of goodness-of-fit and entropy-like measures. Conceptually, it is argued that besides of evaluating the personal performance of the expert, SRs may also play a role when comparing the elicitation processes adopted to obtain f(θ). Mathematically, it is proposed to replace d(θ) by g(θ), the distribution that model the randomness of Θ, and do also considerer goodness-of-fit and entropylike metrics, leading to SRs that measure the adherence of f(θ) to g(θ). The implications of this alternative perspective are discussed and illustrated by means of case studies based on the simulation of controlled experiments. The usefulness of the proposed approach for evaluating the performance of experts and elicitation processes is investigated.
Gowrisankaran, Sowjanya; Genead, Mohamed A.; Anastasakis, Anastasios; Alexander, Kenneth R.
Background This study aimed to determine whether the properties of the late negative responses (LNRs) of the electroretinogram (ERG) elicited by sawtooth flicker are consistent with the characteristics of the photopic negative response generated by a light pulse (PhNRpulse). Methods ERG recordings were obtained from 10 visually normal individuals and from 6 patients with optic atrophy (OA) in response to 8-Hz rapid-on and rapid-off sawtooth flicker and to brief (4 ms) light pulses. All stimuli were either long-wavelength (R), middle-wavelength (G), or a combination of equal luminances of long and middle-wavelengths (Y) presented on a short-wavelength, rod-saturating adapting field. Amplitudes of LNRs were obtained in response to rapid-on (LNRon) and rapid-off (LNRoff) sawtooth flicker, and were also derived from the sum of the ERG waveforms to the two sawtooth phases (LNRadd). Results For the control subjects, PhNRpulse amplitude varied with stimulus wavelength, being largest in response to a long-wavelength pulse, as expected. However, the amplitudes of LNRon, LNRoff, and LNRadd were not significantly different for R, Y, and G sawtooth flicker. Despite the absence of a chromatic effect, LNRoff and LNRadd amplitudes were significantly smaller in the OA patients than in the controls, similar to the results for the PhNRpulse, implying an inner retinal origin for the LNRoff and LNRadd. However, LNRon amplitudes did not differ significantly between the OA patients and controls, although there was a significant correlation between the LNRon and PhNRpulse for R stimuli. Conclusion We conclude that LNRoff and LNRadd but not LNRon can be useful measures to assess the integrity of the inner retina that can complement the PhNRpulse. PMID:23054159
Devinney, Michael J.; Nichols, Nicole L.
Acute intermittent hypoxia (AIH) induces phrenic long-term facilitation (pLTF), a form of spinal motor plasticity. Competing mechanisms give rise to phrenic motor facilitation (pMF; a general term including pLTF) depending on the severity of hypoxia within episodes. In contrast, moderate acute sustained hypoxia (mASH) does not elicit pMF. By varying the severity of ASH and targeting competing mechanisms of pMF, we sought to illustrate why moderate AIH (mAIH) elicits pMF but mASH does not. Although mAIH elicits serotonin-dependent pLTF, mASH does not; thus, mAIH-induced pLTF is pattern sensitive. In contrast, severe AIH (sAIH) elicits pLTF through adenosine-dependent mechanisms, likely from greater extracellular adenosine accumulation. Because serotonin- and adenosine-dependent pMF interact via cross talk inhibition, we hypothesized that pMF is obscured because the competing mechanisms of pMF are balanced and offsetting during mASH. Here, we demonstrate the following: (1) blocking spinal A2A receptors with MSX-3 reveals mASH-induced pMF; and (2) sASH elicits A2A-dependent pMF. In anesthetized rats pretreated with intrathecal A2A receptor antagonist injections before mASH (PaO2 = 40–54 mmHg) or sASH (PaO2 = 25–36 mmHg), (1) mASH induced a serotonin-dependent pMF and (2) sASH induced an adenosine-dependent pMF, which was enhanced by spinal serotonin receptor inhibition. Thus, competing adenosine- and serotonin-dependent mechanisms contribute differentially to pMF depending on the pattern/severity of hypoxia. Understanding interactions between these mechanisms has clinical relevance as we develop therapies to treat severe neuromuscular disorders that compromise somatic motor behaviors, including breathing. Moreover, these results demonstrate how competing mechanisms of plasticity can give rise to pattern sensitivity in pLTF. SIGNIFICANCE STATEMENT Intermittent hypoxia elicits pattern-sensitive spinal plasticity and improves motor function after spinal injury or
Maurer, K; Schröder, K; Schäfer, E
The measurement of sound pressure wave forms of different headphones resulted in considerable differences in an artificial ear and in the external auditory canal in man. This concerns, in particular, the pattern of stimuli used to elicit the auditory nerve and brain-stem auditory evoked potentials. By varying the electrical input to the headphones by means of a programmable stimulus generator, it can be shown that the sound pressure wave form can be influenced considerably.
Shahan, Timothy A.; Chase, Philip N.
Although behavior analysis has been criticized for failure to account for response novelty, many common behavior-analytic concepts and processes (e.g., selectionism, the operant, reinforcement, and stimulus control) assume variability both in the environment and in behavior. The importance of the relation between variability and novelty, particularly for verbal behavior, is discussed, and concepts used to account for novel behavior are examined. Experimental findings also are reviewed that suggest that variability in behavior can come under discriminative control, and these findings are applied to describe novel instances of behavior that may arise during problem solving. We conclude that variations provided and selected by the terms of the three-term contingency are powerful means for understanding novel behavior. PMID:22478385
Muratore, Robert; LaManna, Justine K.; Lamprecht, Michael R.; Morrison, Barclay, III
Among current modalities, ultrasound uniquely offers both millisecond and millimeter accuracy in noninvasively stimulating brain tissue. In addition, by sweeping the ultrasound beam within the refractory period of the neuronal tissue, ultrasonic neuromodulation can be adapted to target extended or multiply connected regions with quasi-simultaneity. Towards the development of this safe brain stimulus technique, the response of rat hippocampal cultures to ultrasound was investigated. Hippocampal slices, 0.4-mm thick, were obtained from 8-day old Sprague Dawley rats and cultured for 6 days. The in vitro cultures were exposed to multiple 100-ms 4.04-MHz ultrasound pulses from a 42-mm diameter, 90-mm spherical cap transducer. Peak pressure ranged from 0 through about 77 kPa. Responses in the form of electrical potentials from a sixty channel electrode array were digitized and recorded. The DG and CA1 regions of the hippocampus exhibited similar ultrasonically-evoked field potentials.
Doualot, Audrey; Simard, Mathieu; Saint-Amour, Dave
Stimulus rivalry refers to the sustained periods of perceptual dominance that occur when different visual stimuli are swapped at a regular rate between eyes. This phenomenon is thought to involve mainly eye-independent mechanisms. Although several studies have reported that attention can increase image predominance in conventional binocular rivalry, it is unknown whether attention can specifically modulate stimulus rivalry. We addressed this question and manipulated the spatial characteristic of the stimuli to assess whether such an attention modulation could depend on visual processing hierarchy. The results showed that selective attention of stimulus rivalry significantly increased the predominance of the attended stimulus, regardless of the stimulus' spatial characteristics. No effect was observed on the swapping percept. The findings are discussed in the context of recent models attempting to characterize stimulus rivalry between eye-dependent and eye-independent levels. PMID:25469220
Antonio-Santos, Aileen; Powell, Christine; Vedula, Satyanarayana S
Background Stimulus deprivation amblyopia (SDA) develops due to an obstruction to the clear passage of light, preventing clear formation of an image on the retina for example, cataract, ptosis (droopy eyelid). It is particularly severe and can be resistant to treatment and the visual prognosis is often poor. Stimulus deprivation amblyopia is rare and precise estimates of prevalence difficult to come by; it probably constitutes less than 3% of all cases of amblyopia. In developed countries most patients present under the age of one; in less developed parts of the world presentation is likely to be significantly later than this. The mainstay of treatment is patching of the better-seeing eye but regimes vary, treatment is difficult to execute and results are often disappointing. Objectives The objectives of this review were to evaluate the effectiveness of occlusion treatment for SDA, determine the optimum treatment regime and factors that may affect outcome. Search strategy We searched the Cochrane Central Register of Controlled Trials - CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) on The Cochrane Library (2006, Issue 1), MEDLINE (1996 to April 2006), EMBASE (1980 to April 2006) and LILACS (Latin American and Caribbean Literature on Health Sciences) (to November 2004). There were no date or language restrictions. Selection criteria We aimed to include randomised and quasi-randomised controlled trials of subjects with unilateral SDA defined as worse than 0.2 LogMAR or equivalent. There were no restrictions with respect to age, gender, ethnicity, co-morbidities, medication use, and the number of participants. Data collection and analysis Two authors independently assessed study abstracts identified by the electronic searches. Main results No trials were identified that met the inclusion criteria. Authors' conclusions It is not possible to conclude how effective treatment for SDA is or which treatment regime produces the best results
Cappaert, Natalie L M; Ramekers, Dyan; Martens, Hubert C F; Wadman, Wytse J
Most deep brain stimulators apply rectangular monophasic voltage pulses. By modifying the stimulus shape, it is possible to optimize stimulus efficacy and find the best compromise between clinical effect, minimal side effects and power consumption of the stimulus generator. In this study, we compared the efficacy of three types of charge-balanced biphasic pulses (CBBPs, nominal duration 100 μs) in isolated sciatic nerves and in in vitro hippocampal brain slices of the rat. Using these two models, we tested the efficacy of several stimulus shapes exclusively on axons (in the sciatic nerve) and compared the effect with that of stimuli in the more complex neuronal network of the hippocampal slice by considering the stimulus-response relation. We showed that (i) adding an interphase gap (IPG, range 100-500 μs) to the CBBP enhances stimulus efficacy in the rat sciatic nerve and (ii) that this type of stimuli (CBBP with IPG) is also more effective in hippocampal slices. This benefit was similar for both models of voltage and current stimulation. In our two models, asymmetric CBBPs were less beneficial. Therefore, CBBPs with IPG appear to be well suited for application to DBS, since they enhance efficacy, extend battery life and potentially reduce harmful side effects.
Haines, R F; Kiefel, S M
Vertical displacement thresholds (DT) were quantified in 24 observers at the fovea and each of 8 retinal positions out to 80 degrees along the horizontal meridian during binocular viewing. Stimulus length was increased with eccentricity angle in accordance with the cortical magnification factor (21); a 1 degree arc long stimulus served as a control at each position. Three movement durations (from 0.25 to 4 s) and three angular rates (from 0.04 to 0.42 degrees arc.s-1) were also quantified at each position to determine whether peripheral DT is mediated predominantly by an image displacement- or rate-sensitive mechanism. It was found that 1) DT is mediated predominantly by a constant rate-sensitive mechanism at each position when stimulus length is increased in proportion to the cortical magnification factor; 2) mean percent correct displacement judgments decrease significantly into the periphery for both stimulus lengths, however, increasing stimulus length yields significantly higher accuracy; and 3) at 10 and 30 degrees eccentricity, increasing rate and duration significantly improve displacement judgment accuracy, but beyond 40 degrees only lengthening the stimulus improves accuracy. The findings are related to the design optimization of dynamic attitude displays and symbology for aircraft.
Sobral, G. A., Jr.; Vieira, V. M.; Lyra, M. L.; da Silva, C. R.
Extending a model due to Derrida, Gardner, and Zippelius, we have studied the recognition ability of an extreme and asymmetrically diluted version of the Hopfield model for associative memory by including the effect of a stimulus in the dynamics of the system. We obtain exact results for the dynamic evolution of the average network superposition. The stimulus field was considered as proportional to the overlapping of the state of the system with a particular stimulated pattern. Two situations were analyzed, namely, the external stimulus acting on the initialization pattern (parallel stimulus) and the external stimulus acting on a pattern orthogonal to the initialization one (orthogonal stimulus). In both cases, we obtained the complete phase diagram in the parameter space composed of the stimulus field, thermal noise, and network capacity. Our results show that the system improves its recognition ability for parallel stimulus. For orthogonal stimulus two recognition phases emerge with the system locking at the initialization or stimulated pattern. We confront our analytical results with numerical simulations for the noiseless case T=0 .
Sobral, G A; Vieira, V M; Lyra, M L; da Silva, C R
Extending a model due to Derrida, Gardner, and Zippelius, we have studied the recognition ability of an extreme and asymmetrically diluted version of the Hopfield model for associative memory by including the effect of a stimulus in the dynamics of the system. We obtain exact results for the dynamic evolution of the average network superposition. The stimulus field was considered as proportional to the overlapping of the state of the system with a particular stimulated pattern. Two situations were analyzed, namely, the external stimulus acting on the initialization pattern (parallel stimulus) and the external stimulus acting on a pattern orthogonal to the initialization one (orthogonal stimulus). In both cases, we obtained the complete phase diagram in the parameter space composed of the stimulus field, thermal noise, and network capacity. Our results show that the system improves its recognition ability for parallel stimulus. For orthogonal stimulus two recognition phases emerge with the system locking at the initialization or stimulated pattern. We confront our analytical results with numerical simulations for the noiseless case T = 0.
van de Nieuwenhuijzen, Marieke E.; van den Borne, Eva W. P.; Jensen, Ole; van Gerven, Marcel A. J.
Visual perception is a spatiotemporally complex process. In this study, we investigated cortical dynamics during and after stimulus presentation. We observed that visual category information related to the difference between faces and objects became apparent in the occipital lobe after 63 ms. Within the next 110 ms, activation spread out to include the temporal lobe before returning to residing mainly in the occipital lobe again. After stimulus offset, a peak in information was observed, comparable to the peak after stimulus onset. Moreover, similar processes, albeit not identical, seemed to underlie both peaks. Information about the categorical identity of the stimulus remained present until 677 ms after stimulus offset, during which period the stimulus had to be retained in working memory. Activation patterns initially resembled those observed during stimulus presentation. After about 200 ms, however, this representation changed and class-specific activity became more equally distributed over the four lobes. These results show that, although there are common processes underlying stimulus representation both during and after stimulus presentation, these representations change depending on the specific stage of perception and maintenance. PMID:27242453
Hecox, K.; Squires, N.; Galambos, R.
Short latency (under 10 msec) evoked responses elicited by bursts of white noise were recorded from the scalp of human subjects. Response alterations produced by changes in the noise burst duration (on-time) inter-burst interval (off-time), and onset and offset shapes are reported and evaluated. The latency of the most prominent response component, wave V, was markedly delayed with increases in stimulus rise-time but was unaffected by changes in fall-time. The amplitude of wave V was insensitive to changes in signal rise-and-fall times, while increasing signal on-time produced smaller amplitude responses only for sufficiently short off-times. It is concluded that wave V of the human auditory brainstem evoked response is solely an onset response.
Silveira, Mariana Ribeiro Marcondes da; Andrade, Joaquina; Garzon, Eliana
SIRPIDs, an acronym for stimulus-induced rhythmic, periodic, or ictal discharges, were first named in 2004. This is a pattern observed in continuous electroencephalogram (CEEG) consistently elicited by stimulation in comatose patients. The pathophysiology of SIRPIDs probably involves dysregulation of subcortico-cortical projections, particularly thalamocortical circuit, in a markedly abnormal brain with hyperexci-table cortex. This may explain some studies found an association of prolonged periodic epileptiform discharges (PEDs) activity and a higher incidence of concurrent electrographic seizures and SIRPIDs. An association of SIRPIDs and poor prognosis has already been described. However, it is not yet possible to assert whether these discharges can cause neuronal injury or if they are simply a marker of severe brain injury. Objective of this paper is to review clinical relevance and pathophysiology of SIRPIDs, as well as its role as a brain response in the critically ill patient.
Laszlo, Sarah; Federmeier, Kara D.
An assumption in the reading literature is that access to semantics is gated by stimulus properties such as orthographic regularity or familiarity. In the electrophysiological domain, this assumption has led to a debate about the features necessary to initiate semantic processing as indexed by theN400 event-related potential (ERP) component. To examine this, we recorded ERPs to sentences with endings that were familiar and legal (words), familiar and illegal (acronyms), or unfamiliar and illegal (consonant or vowel strings). N400 congruency effects (reduced negativity to expected relative to unexpected endings) were observed for words and acronyms; these were identical in size, timing, and scalp distribution. Notably, clear N400 potentials were also elicited by unfamiliar, illegal strings, suggesting that, at least in a verbal context, semantic access may be attempted for any letter string, regardless of familiarity or regularity. PMID:18221447
Wilson, Dan; Holt, Abbey B; Netoff, Theoden I; Moehlis, Jeff
We develop a methodology to design a stimulus optimized to entrain nonlinear, noisy limit cycle oscillators with uncertain properties. Conditions are derived which guarantee that the stimulus will entrain the oscillators despite these uncertainties. Using these conditions, we develop an energy optimal control strategy to design an efficient entraining stimulus and apply it to numerical models of noisy phase oscillators and to in vitro hippocampal neurons. In both instances, the optimal stimuli outperform other similar but suboptimal entraining stimuli. Because this control strategy explicitly accounts for both noise and inherent uncertainty of model parameters, it could have experimental relevance to neural circuits where robust spike timing plays an important role.
Introduction: Smoking initiation usually begins in adolescence, but how and for whom nicotine dependence emerges during this period is unclear. The cue-reactivity paradigm is well suited to examine one marker of dependence: craving-related stimulus control, i.e., the ability of environmental cues to elicit craving to smoke. This study examined the effects of both level of smoking involvement (daily vs. occasional smoking) and gender on reactivity to both smoking and alcohol cues. Methods: Young (age range 16–20; 42% female) daily (n = 55) and occasional (n = 52) smokers were exposed to each of three counterbalanced cues: (a) in vivo smoking (e.g., sight, smell, lighting of cigarette), (b) alcohol (e.g., opening, pouring, and smell of preferred beverage), and (c) neutral cue. Results: Daily smokers exhibited higher levels of tonic (i.e., noncue-elicited) craving than did occasional smokers. Both groups showed significant increases in craving in response to cues (i.e., cue-elicited craving), with little evidence that cue-elicited craving differed between groups. Females were more cue reactive to both the alcohol and smoking cues than males, particularly for the positively reinforced aspects of smoking (i.e., hedonic craving). There were no gender × group interaction effects in response to either the alcohol or the smoking cue. Conclusions: Findings show the presence of cue-elicited craving even among occasional smokers and are consistent with literature demonstrating heightened sensitivity to environmental cues among females. Cue-elicited craving may be one mechanism that contributes to the maintenance of smoking behavior and perhaps to the development of nicotine dependence within early stage smokers. PMID:24042699
Gorelick, David A.; Goodwin, Robert S.; Schwilke, Eugene; Schwope, David M.; Darwin, William D.; Kelly, Deanna L.; McMahon, Robert P.; Liu, Fang; Ortemann-Renon, Catherine; Bonnet, Denis; Huestis, Marilyn A.
Cannabinoid CB1 receptor antagonists have potential therapeutic benefits, but antagonist-elicited cannabis withdrawal has not been reported in humans. Ten male daily cannabis smokers received 8 days of increasingly frequent 20-mg oral Δ9-tetrahydrocannabinol (THC) dosages (40–120 mg/d) around-the-clock to standardize cannabis dependence while residing on a closed research unit. On the ninth day, double-blind placebo or 20- (suggested therapeutic dose) or 40-mg oral rimonabant, a CB1-cannabinoid receptor antagonist, was administered. Cannabis withdrawal signs and symptoms were assessed before and for 23.5 hours after rimonabant. Rimonabant, THC, and 11-hydroxy-THC plasma concentrations were quantified by mass spectrometry. The first 6 subjects received 20-mg rimonabant (1 placebo); the remaining 4 subjects received 40-mg rimonabant (1 placebo). Fourteen subjects enrolled; 10 completed before premature termination because of withdrawal of rimonabant from clinical development. Three of 5 subjects in the 20-mg group, 1 of 3 in the 40-mg group, and none of 2 in the placebo group met the prespecified withdrawal criterion of 150% increase or higher in at least 3 visual analog scales for cannabis withdrawal symptoms within 3 hours of rimonabant dosing. There were no significant associations between visual analog scale, heart rate, or blood pressure changes and peak rimonabant plasma concentration, area-under-the-rimonabant-concentration-by-time curve (0–8 hours), or peak rimonabant/THC or rimonabant/(THC + 11-hydroxy-THC) plasma concentration ratios. In summary, prespecified criteria for antagonist-elicited cannabis withdrawal were not observed at the 20- or 40-mg rimonabant doses. These data do not preclude antagonist-elicited withdrawal at higher rimonabant doses. PMID:21869692
Coppersmith, K. J.
This report presents results of the Unsaturated Zone Flow Model Expert Elicitation (UZFMEE) project at Yucca Mountain, Nevada. This project was sponsored by the US Department of Energy (DOE) and managed by Geomatrix Consultants, Inc. (Geomatrix), for TRW Environmental Safety Systems, Inc. The objective of this project was to identify and assess the uncertainties associated with certain key components of the unsaturated zone flow system at Yucca Mountain. This assessment reviewed the data inputs, modeling approaches, and results of the unsaturated zone flow model (termed the ''UZ site-scale model'') being developed by Lawrence Berkeley National Laboratory (LBNL) and the US Geological Survey (USGS). In addition to data input and modeling issues, the assessment focused on percolation flux (volumetric flow rate per unit cross-sectional area) at the potential repository horizon. An understanding of unsaturated zone processes is critical to evaluating the performance of the potential high-level nuclear waste repository at Yucca Mountain. A major goal of the project was to capture the uncertainties involved in assessing the unsaturated flow processes, including uncertainty in both the models used to represent physical controls on unsaturated zone flow and the parameter values used in the models. To ensure that the analysis included a wide range of perspectives, multiple individual judgments were elicited from members of an expert panel. The panel members, who were experts from within and outside the Yucca Mountain project, represented a range of experience and expertise. A deliberate process was followed in facilitating interactions among the experts, in training them to express their uncertainties, and in eliciting their interpretations. The resulting assessments and probability distributions, therefore, provide a reasonable aggregate representation of the knowledge and uncertainties about key issues regarding the unsaturated zone at the Yucca Mountain site.
Gorelick, David A; Goodwin, Robert S; Schwilke, Eugene; Schwope, David M; Darwin, William D; Kelly, Deanna L; McMahon, Robert P; Liu, Fang; Ortemann-Renon, Catherine; Bonnet, Denis; Huestis, Marilyn A
Cannabinoid CB1 receptor antagonists have potential therapeutic benefits, but antagonist-elicited cannabis withdrawal has not been reported in humans. Ten male daily cannabis smokers received 8 days of increasingly frequent 20-mg oral Δ⁹-tetrahydrocannabinol (THC) dosages (40-120 mg/d) around-the-clock to standardize cannabis dependence while residing on a closed research unit. On the ninth day, double-blind placebo or 20- (suggested therapeutic dose) or 40-mg oral rimonabant, a CB1-cannabinoid receptor antagonist, was administered. Cannabis withdrawal signs and symptoms were assessed before and for 23.5 hours after rimonabant. Rimonabant, THC, and 11-hydroxy-THC plasma concentrations were quantified by mass spectrometry. The first 6 subjects received 20-mg rimonabant (1 placebo); the remaining 4 subjects received 40-mg rimonabant (1 placebo). Fourteen subjects enrolled; 10 completed before premature termination because of withdrawal of rimonabant from clinical development. Three of 5 subjects in the 20-mg group, 1 of 3 in the 40-mg group, and none of 2 in the placebo group met the prespecified withdrawal criterion of 150% increase or higher in at least 3 visual analog scales for cannabis withdrawal symptoms within 3 hours of rimonabant dosing. There were no significant associations between visual analog scale, heart rate, or blood pressure changes and peak rimonabant plasma concentration, area-under-the-rimonabant-concentration-by-time curve (0-8 hours), or peak rimonabant/THC or rimonabant/(THC + 11-hydroxy-THC) plasma concentration ratios. In summary, prespecified criteria for antagonist-elicited cannabis withdrawal were not observed at the 20- or 40-mg rimonabant doses. These data do not preclude antagonist-elicited withdrawal at higher rimonabant doses.
Heyman, Gail D; Fu, Genyue; Lin, Jianyan; Qian, Miao K; Lee, Kang
Widespread cheating can undermine rules that are necessary for maintaining social order. Preventing cheating can be a challenge, especially with regard to children, who as a result of their limited executive function skills may have particular difficulty with resisting temptation to cheat. We examined one approach designed to help children resist this temptation: eliciting a verbal commitment to not cheat. We tested 4- to 7-year-olds (total N = 330) and found that starting at 5 years of age, a verbal commitment to not cheat led to a substantial reduction in cheating. The results suggest that verbal commitments can be used to help children overcome temptations and comply with rules.
Sato, A; Liu, X; Torii, T; Iwahashi, M; Iramina, K; Sato, A; Liu, X; Torii, T; Iwahashi, M; Iramina, K; Iwahashi, M; Liu, X; Sato, A; Iramina, K; Torii, T
Peripheral stimulation is known to influence the state of cortical excitability. The purpose of this study is to investigate whether peripheral magnetic stimulation has similar effects on cortical excitability to transcranial magnetic stimulation (TMS). A magnetic stimulator with a flat figure-of-eight coil was used for both TMS, and peripheral magnetic stimulation applied to the bilateral forearms. TMS was performed on the left primary motor cortex to evaluate influence of the peripheral magnetic stimulation, and motor evoked potential (MEP) was measured from the right first dorsal interosseous. Peripheral magnetic stimulation was performed at a stimulus frequency of 1 Hz or 10 Hz, to the stimulus sites on the right and left supination of the forearm. The effects of peripheral magnetic stimulation were evaluated by comparing the mean MEP amplitude elicited by TMS before and after peripheral magnetic stimulation. We found that cortical excitability varied according to the stimulation site and frequency of the peripheral magnetic stimulation. The inhibition of cortical excitability was observed following 1 Hz peripheral magnetic stimulation over the right forearm (p<;0.001). In contrast, increased cortical excitability was observed using 1 Hz peripheral magnetic stimulation over the left forearm and 10 Hz stimulation over either the right or left forearms. We suggest that peripheral magnetic stimulation has a similar effect to TMS, and can induce both facilitation and inhibition of cortical excitability.
Stimulus-specific adaptation (SSA) occurs when neurons decrease their responses to frequently-presented (standard) stimuli but not, or not as much, to other, rare (deviant) stimuli. SSA is present in all mammalian species in which it has been tested as well as in birds. SSA confers short-term memory to neuronal responses, and may lie upstream of the generation of mismatch negativity (MMN), an important human event-related potential. Previously published models of SSA mostly rely on synaptic depression of the feedforward, thalamocortical input. Here we study SSA in a recurrent neural network model of primary auditory cortex. When the recurrent, intracortical synapses display synaptic depression, the network generates population spikes (PSs). SSA occurs in this network when deviants elicit a PS but standards do not, and we demarcate the regions in parameter space that allow SSA. While SSA based on PSs does not require feedforward depression, we identify feedforward depression as a mechanism for expanding the range of parameters that support SSA. We provide predictions for experiments that could help differentiate between SSA due to synaptic depression of feedforward connections and SSA due to synaptic depression of recurrent connections. Similar to experimental data, the magnitude of SSA in the model depends on the frequency difference between deviant and standard, probability of the deviant, inter-stimulus interval and input amplitude. In contrast to models based on feedforward depression, our model shows true deviance sensitivity as found in experiments. PMID:28288158
Takeuchi, T; Miyasita, A; Sasaki, Y; Inugami, M; Fukuda, K
We elicited isolated sleep paralysis (ISP) from normal subjects by a nocturnal sleep interruption schedule. On four experimental nights, 16 subjects had their sleep interrupted for 60 minutes by forced awakening at the time when 40 minutes of nonrapid eye movement (NREM) sleep had elapsed from the termination of rapid eye movement (REM) sleep in the first or third sleep cycle. This schedule produced a sleep onset REM period (SOREMP) after the interruption at a high rate of 71.9%. We succeeded in eliciting six episodes of ISP in the sleep interruptions performed (9.4%). All episodes of ISP except one occurred from SOREMP, indicating a close correlation between ISP and SOREMP. We recorded verbal reports about ISP experiences and recorded the polysomnogram (PSG) during ISP. All of the subjects with ISP experienced inability to move and were simultaneously aware of lying in the laboratory. All but one reported auditory/visual hallucinations and unpleasant emotions. PSG recordings during ISP were characterized by a REM/W stage dissociated state, i.e. abundant alpha electroencephalographs and persistence of muscle atonia shown by the tonic electromyogram. Judging from the PSG recordings, ISP differs from other dissociated states such as lucid dreaming, nocturnal panic attacks and REM sleep behavior disorders. We compare some of the sleep variables between ISP and non-ISP nights. We also discuss the similarities and differences between ISP and sleep paralysis in narcolepsy.
Topolinski, Sascha; Strack, Fritz
The authors apply an embodied account to mere exposure, arguing that through the repeated exposure of a particular stimulus, motor responses specifically associated to that stimulus are repeatedly simulated, thus trained, and become increasingly fluent. This increased fluency drives preferences for repeated stimuli. This hypothesis was tested by…
Graham, Robert B.
Describes a computer tutorial that teaches the fundamentals of stimulus generalization in operant learning. Concepts covered include reinforcement, discrimination learning, stimulus continua, generalization, generalization gradients, and peak shift. The tutorial also reviews applications in human and animal situations. The content is appropriate…
Machell, David F.
Discusses theory of stimulus addiction, a process of human accommodation to stimuli which fosters dependency and may foster addiction. Suggests that a society of affluence may be prone to addictiveness because the more continuous the stimuli the person experiences, the more tolerance is created, and with tolerance comes stimulus deprivation.…
Geeraerts, Sarah; Lafosse, Christophe; Vandenbussche, Erik; Verfaillie, Karl
Patients showing visual extinction as a consequence of a unilateral brain lesion can correctly detect a single stimulus in either hemifield but fail to detect the contralesional stimulus (or at least process the stimulus less efficiently) when it is presented simultaneously with an ipsilesional stimulus. In an attempt to uncover the nature of the underlying deficit, some studies have manipulated the temporal characteristics of stimulus presentation. Contra- and ipsilesional stimuli with different stimulus onset asynchronies are typically used. In the present study, visual extinction was investigated in a group of left neglect patients (N=10) using a psychophysical paradigm with different stimulus onset asynchronies of target and distractor stimuli presented in different hemifields. Contrast thresholds for a target grating were determined with the target either in isolation or in the presence of an irrelevant distractor grating. When target and distractor gratings were presented simultaneously, neglect patients showed a significant extinction effect, i.e., a significant interference from the right hemifield distractor with left hemifield contrast sensitivity. When the right hemifield distractor preceded the left hemifield target stimulus by 250 ms, two different patterns of results were observed in the neglect patients. Five patients showed a significant improvement compared to the simultaneous presentation condition, five other patients showed a significant increase of the extinction effect. The results suggest that different underlying mechanisms, maybe due to different lesion locations, can cause extinction in neglect patients.
Brosseau-Lapre, Francoise; Rvachew, Susan; Clayards, Meghan; Dickson, Daniel
English-speakers' learning of a French vowel contrast (/schwa/-/slashed o/) was examined under six different stimulus conditions in which contrastive and noncontrastive stimulus dimensions were varied orthogonally to each other. The distribution of contrastive cues was varied across training conditions to create single prototype, variable far…
Isu, N; Shimizu, T; Sugata, K
To specify inducing factors of motion sickness comprised in Coriolis stimulus, or cross-coupled rotation, the sensation of rotation derived from the semicircular canal system during and after Coriolis stimulus under a variety of stimulus conditions, was estimated by an approach from mechanics with giving minimal hypotheses and simplifications on the semicircular canal system and the sensory nervous system. By solving an equation of motion of the endolymph during Coriolis stimulus, rotating angle of the endolymph was obtained, and the sensation of rotation derived from each semicircular canal was estimated. Then the sensation derived from the whole semicircular canal system was particularly considered in two cases of a single Coriolis stimulus and cyclic Coriolis stimuli. The magnitude and the direction of sensation of rotation were shown to depend on an angular velocity of body rotation and a rotating angle of head movement (amplitude of head oscillation when cyclic Coriolis stimuli) irrespective of initial angle (center angle) of the head relative to the vertical axis. The present mechanical analysis of Coriolis stimulus led a suggestion that the severity of nausea evoked by Coriolis stimulus is proportional to the effective value of the sensation of rotation caused by the Coriolis stimulus.
Erickson, Jonathan C.; Shingiro, Aristide; Bowen, Thomas
Swarms of insects instrumented with wireless electronic backpacks have previously been proposed for potential use in search and rescue operations. Before deploying such biobot swarms, an effective long-term neural-electric stimulus interface must be established, and the locomotion response to various stimuli quantified. To this end, we studied a variety of pulse types (mono- vs. bipolar; voltage- vs. current-controlled) and shapes (amplitude, frequency, duration) to parameters that are most effective for evoking locomotion along a desired path in the Madagascar hissing cockroach (G. portentosa) in response to antennal and cercal stimulation. We identified bipolar, 2 V, 50 Hz, 0.5 s voltage controlled pulses as being optimal for evoking forward motion and turns in the expected contraversive direction without habituation in ≈50% of test subjects, a substantial increase over ≈10% success rates previously reported. Larger amplitudes for voltage (1–4 V) and current (50–150 μA) pulses generally evoked larger forward walking (15.6–25.6 cm; 3.9–5.6 cm/s) but smaller concomitant turning responses (149 to 80.0 deg; 62.8 to 41.2 deg/s). Thus, the radius of curvature of the initial turn-then-run locomotor response (≈10–25 cm) could be controlled in a graded manner by varying the stimulus amplitude. These findings could be used to help optimize stimulus protocols for swarms of cockroach biobots navigating unknown terrain. PMID:26308337
Glass, Brian D.; Maddox, W. Todd; Markmana, Arthur B.
This article examines the effects of a fit between a person's global regulatory focus and the local task reward structure on perceptual processing and judgment. On each trial, participants were presented with one of two briefly presented stimuli and were asked to identify it. Participants were placed in a promotion focus (a situationally induced sensitivity to gains) or a prevention focus (a situationally induced sensitivity to losses) and were asked to maximize gains or minimize losses. An asymmetric payoff ratio biased the overall reward toward one identification response over the other. Two experiments tested the role of regulatory fit when internal familiarity and perceptual sensitivity was low or high. When familiarity and sensitivity were low, participants in a regulatory fit (promotion focus with gains or a prevention focus with losses) showed greater perceptual sensitivity, but no response bias differences relative to participants in a regulatory mismatch. When familiarity and sensitivity were high, participants in a regulatory fit showed a response bias toward the high payoff stimulus, but no differences in perceptual sensitivity. Speculation on the neurobiological basis of this effect, as well as implications of this work for clinical disorders, such as depression, is offered. PMID:21264696
Murray, Jennifer E; Li, Chia; Palmatier, Matthew I; Bevins, Rick A
The present research sought to test whether caffeine functioned as a Pavlovian cue in two ways--as a positive drug feature or as a conditional stimulus (CS). As a positive feature (Experiment 1), brief light presentations were followed by sucrose only on sessions in which caffeine (10 mg/kg) was administered. On intermixed saline sessions, light presentations were not followed by sucrose. The light came to control robust goal tracking (i.e., conditioned responding) only in caffeine sessions. Thus, caffeine disambiguates when the light was paired with sucrose. Decreasing the dose of caffeine decreased the conditioned responding evoked by the light (ED(50)=4.16 mg/kg). Neither nicotine nor amphetamine substituted for the caffeine feature. As a CS, caffeine (10 or 30 mg/kg, Experiments 2a and 2b, respectively) signaled intermittent access to sucrose--no light presentations. No sucrose or lights were presented on intermixed saline sessions. The caffeine CS, regardless of training dose, acquired the ability to evoke only a weak goal-tracking CR. The nature of this dissociation between caffeine as a drug feature and a CS is discussed within the context of past research finding a similar dissociation with amphetamine and chlordiazepoxide, but not with nicotine.
Ninness, Chris; Barnes-Holmes, Dermot; Rumph, Robin; McCuller, Glen; Ford, Angela M; Payne, Robert; Ninness, Sharon K; Smith, Ronald J; Ward, Todd A; Elliott, Marc P
Following a pretest, 8 participants who were unfamiliar with algebraic and trigonometric functions received a brief presentation on the rectangular coordinate system. Next, they participated in a computer-interactive matching-to-sample procedure that trained formula-to-formula and formula-to-graph relations. Then, they were exposed to 40 novel formula-to-graph tests and 10 novel graph-to-formula tests. Seven of the 8 participants showed substantial improvement in identifying formula-to-graph relations; however, in the test of novel graph-to-formula relations, participants tended to select equations in their factored form. Next, we manipulated contextual cues in the form of rules regarding mathematical preferences. First, we informed participants that standard forms of equations were preferred over factored forms. In a subsequent test of 10 additional novel graph-to-formula relations, participants shifted their selections to favor equations in their standard form. This preference reversed during 10 more tests when financial reward was made contingent on correct identification of formulas in factored form. Formula preferences and transformation of novel mathematical and stimulus functions are discussed.
Testa, S Marc; Ward, Julianna; Crone, Nathan E; Brandt, Jason
The effects of amytal injection side, seizure focus laterality, and stimulus type (real and line-drawn objects, printed words, and faces) on recognition memory were studied during the Wada procedure. To-be-remembered stimuli were presented during cerebral anesthesia to 35 patients with left temporal lobe epilepsy (LTLE) and 28 patients with right temporal lobe epilepsy (RTLE), all with left hemisphere language dominance. In both groups, recognition of real and line-drawn objects was best after anesthetization of the lesional hemisphere. Recognition of faces was poor after either injection in patients with RTLE, but only after right injection in patients with LTLE. Conversely, recognition of words by patients with LTLE was impaired equally after either injection, but more so after left than right injection in patients with RTLE. The findings suggest that (1) real and line-drawn objects are "dually encoded" and memory accuracy depends on seizure focus laterality, and (2) accuracy in recognition of words and faces is related to seizure focus laterality, but may also depend on the language dominance of the hemisphere being assessed.
Strouse, A; Wilson, R H
Dichotic digit listening was made more difficult by interleaving one-, two-, three-, and four-pair digits within a test list in which the subjects did not know a priori the number of digit pairs presented on a given trial, thereby introducing listener uncertainty. Twenty right-handed (mean age = 26.8 years) and 20 left-handed adults (mean age = 24.0) with normal hearing and 40 right-handed adults in the 60- to 75-years age range (mean age = 67.2) with mild-to-moderate sensorineural hearing loss were evaluated. Compared to traditional paradigms, the uncertainty of stimulus length (one, two, three, or four pairs) reduced overall recognition performance on stimuli presented to both ears of all groups, but the reduction was more pronounced for the left ear than for the right ear. The recognition performance of the right-handed subjects was more homogeneous than the performance of the left-handed subjects. In comparison to the young subjects, the 60- to 75-year-old group had substantially reduced recognition performance.
Furlong, T M; Pan, M J; Corbit, L H
Alcohol-related stimuli can trigger relapse of alcohol-seeking behaviors even after extended periods of abstinence. Extinction of such stimuli can reduce their impact on relapse; however, the expression of extinction can be disrupted when testing occurs outside the context where extinction learning took place, an effect termed renewal. Behavioral and pharmacological methods have recently been shown to augment extinction learning; yet, it is not known whether the improved expression of extinction following these treatments remains context-dependent. Here we examined whether two methods, compound–stimulus extinction and treatment with the noradrenaline reuptake inhibitor atomoxetine, would reduce the vulnerability of extinction to a change in context. Following alcohol self-administration, responding was extinguished in a distinct context. After initial extinction, further extinction was given to a target stimulus presented in compound with another alcohol-predictive stimulus intended to augment prediction error (Experiment 1) or after a systemic injection of atomoxetine (1.0 mg kg−1; Experiment 2). A stimulus extinguished as part of a compound elicited less responding than a stimulus receiving equal extinction alone regardless of whether animals were tested in the training or extinction context; however, reliable renewal was not observed in this paradigm. Importantly, atomoxetine enhanced extinction relative to controls even in the presence of a reliable renewal effect. Thus, extinction of alcohol-seeking behavior can be improved by extinguishing multiple alcohol-predictive stimuli or enhancing noradrenaline neurotransmission during extinction training. Importantly, both methods improve extinction even when the context is changed between extinction training and test, and thus could be utilized to enhance the outcome of extinction-based treatments for alcohol-use disorders. PMID:26327688
Furlong, T M; Pan, M J; Corbit, L H
Alcohol-related stimuli can trigger relapse of alcohol-seeking behaviors even after extended periods of abstinence. Extinction of such stimuli can reduce their impact on relapse; however, the expression of extinction can be disrupted when testing occurs outside the context where extinction learning took place, an effect termed renewal. Behavioral and pharmacological methods have recently been shown to augment extinction learning; yet, it is not known whether the improved expression of extinction following these treatments remains context-dependent. Here we examined whether two methods, compound-stimulus extinction and treatment with the noradrenaline reuptake inhibitor atomoxetine, would reduce the vulnerability of extinction to a change in context. Following alcohol self-administration, responding was extinguished in a distinct context. After initial extinction, further extinction was given to a target stimulus presented in compound with another alcohol-predictive stimulus intended to augment prediction error (Experiment 1) or after a systemic injection of atomoxetine (1.0 mg kg(-1); Experiment 2). A stimulus extinguished as part of a compound elicited less responding than a stimulus receiving equal extinction alone regardless of whether animals were tested in the training or extinction context; however, reliable renewal was not observed in this paradigm. Importantly, atomoxetine enhanced extinction relative to controls even in the presence of a reliable renewal effect. Thus, extinction of alcohol-seeking behavior can be improved by extinguishing multiple alcohol-predictive stimuli or enhancing noradrenaline neurotransmission during extinction training. Importantly, both methods improve extinction even when the context is changed between extinction training and test, and thus could be utilized to enhance the outcome of extinction-based treatments for alcohol-use disorders.
Senders, J. W.; Senders, V. L.; Tursky, B.
An investigation was carried out to determine whether a form of quasi-linear systems analysis can be applied to electrodormal responses to yield new insights into the nature of the response mechanisms and their interrelationships. The response investigated was the electrodermal response (galvanic skin potential, GSP) as elicited by an electric shock stimulus applied to the skin. The response subsequent to this stimulation was examined and its characteristics measured. A series of experimental runs on three Ss was accomplished, using sinusoidal modulation envelopes of frequencies. Results showed that it was possible to drive the GSP and to achieve relatively high coherence between the driving frequency and the response itself. The analysis was limited to Fourier analysis of the response in order to determine the relative energies at the driving frequency and at successive harmonics of that driving frequency, and correlational analysis in order to determine the degree of linear relationship between the driving frequency and the driven response.
Uglesich, Robert; Casti, Alex; Hayot, Fernand; Kaplan, Ehud
Relay cells in the mammalian lateral geniculate nucleus (LGN) are driven primarily by single retinal ganglion cells (RGCs). However, an LGN cell responds typically to less than half of the spikes it receives from the RGC that drives it, and without retinal drive the LGN is silent (Kaplan and Shapley, 1984). Recent studies, which used stimuli restricted to the receptive field (RF) center, show that despite the great loss of spikes, more than half of the information carried by the RGC discharge is typically preserved in the LGN discharge (Sincich et al., 2009), suggesting that the retinal spikes that are deleted by the LGN carry less information than those that are transmitted to the cortex. To determine how LGN relay neurons decide which retinal spikes to respond to, we recorded extracellularly from the cat LGN relay cell spikes together with the slow synaptic (‘S’) potentials that signal the firing of retinal spikes. We investigated the influence of the inhibitory surround of the LGN RF by stimulating the eyes with spots of various sizes, the largest of which covered the center and surround of the LGN relay cell's RF. We found that for stimuli that activated mostly the RF center, each LGN spike delivered more information than the retinal spike, but this difference was reduced as stimulus size increased to cover the RF surround. To evaluate the optimality of the LGN editing of retinal spikes, we created artificial spike trains from the retinal ones by various deletion schemes. We found that single LGN cells transmitted less information than an optimal detector could. PMID:19838326
Roche, B; Barnes, D
Adult male subjects saw a sexual film clip paired with a nonsense syllable (C1). Similarly, an emotionally neutral film clip was paired with a second nonsense syllable (C3). Responses to the nonsense syllables were recorded as skin resistance responses. Subjects were also trained in a series of related conditional discriminations, using the C1 and C3 stimuli, from which the following equivalence relations were predicted; A1-B1-C1, A2-B2-C2, and A3-B3-C3. Some subjects were given matching-to-sample (equivalence) tests after the conditional discrimination training (Experiment 1), whereas others were not (Experiment 2). Subjects were tested for a transformation of eliciting functions by presenting the A1 and A3 stimuli, which were related through equivalence to C1 and C3, respectively. Five of the 6 subjects who showed significantly greater conditioned responses to C1 than to C3, also showed significantly greater skin resistance responses to A1 than to A3. Two additional subjects demonstrated a transformation of an eliciting stimulus function in accordance with five-member equivalence relations (Experiment 3), and another 5 subjects demonstrated similar effects in accordance with the relations of sameness and opposition (Experiment 4). PMID:9163935
Ladu, Fabrizio; Bartolini, Tiziana; Panitz, Sarah G; Chiarotti, Flavia; Butail, Sachit; Macrì, Simone; Porfiri, Maurizio
Emotional disturbances constitute a major health issue affecting a considerable portion of the population in western countries. In this context, animal models offer a relevant tool to address the underlying biological determinants and to screen novel therapeutic strategies. While rodents have traditionally constituted the species of choice, zebrafish are now becoming a viable alternative. As zebrafish gain momentum in biomedical sciences, considerable efforts are being devoted to developing high-throughput behavioral tests. Here, we present a comparative study of zebrafish behavioral response to fear-evoking stimuli offered via three alternative methodologies. Specifically, in a binary-choice test, we exposed zebrafish to an allopatric predator Astronotus ocellatus, presented in the form of a live subject, a robotic replica, and a computer-animated image. The robot's design and operation were inspired by the morphology and tail-beat motion of its live counterpart, thereby offering a consistent three-dimensional stimulus to focal fish. The computer-animated image was also designed after the live subject to replicate its appearance. We observed that differently from computer-animated images, both the live predator and its robotic replica elicited robust avoidance response in zebrafish. In addition, in response to the robot, zebrafish exhibited increased thrashing behavior, which is considered a valid indicator of fear. Finally, inter-individual response to a robotic stimulus is more consistent than that shown in response to live stimuli and animated images, thereby increasing experimental statistical power. Our study supports the view that robotic stimuli can constitute a promising experimental tool to elicit targeted behavioral responses in zebrafish.
Cohn, Scott I; Weiss, Stanley J
Previous experiments have demonstrated that the simultaneous presentation of independently established discriminative stimuli can control rates of operant responding substantially higher than the rates occasioned by the individual stimuli. This “additive summation” phenomenon has been shown with a variety of different reinforcers (e.g., food, water, shock avoidance, cocaine, and heroin). Discriminative stimuli previously used in such studies have been limited to the visual and auditory sensory modalities. The present experiment sought to (1) establish stimulus control on a free-operant baseline with an ambient olfactory discriminative stimulus, (2) compare olfactory control to that produced with an auditory discriminative stimulus, and (3) determine whether compounding independently established olfactory and auditory discriminative stimuli produces additive summation. Rats lever pressed for food on a variable-interval schedule in the presence of either a tone or an odor, with comparable control developed to each stimulus. In the absence of these stimuli responding was not reinforced. During stimulus compounding tests, the tone-plus-odor compound occasioned more than double the responses occasioned by either the tone or odor presented individually. Thus, the current study (1) established stimulus control with an ambient olfactory discriminative stimulus in a traditional free-operant setting and (2) extended the generality of stimulus-compounding effects by demonstrating additive summation when olfactory and auditory discriminative stimuli were presented simultaneously. PMID:17465315
Helsley, S; Fiorella, D; Rabin, R A; Winter, J C
1. A series of N-substituted tryptamines was compared with a series of beta-carbolines in rats trained to discriminate LSD (0.1 mg/kg) from saline. 2. Intermediate levels of substitution were elicited by MDMT (76.4%), DMT (77.9%), and DET (48.7%). 6-F-DET produced 41.3% LSD-appropriate responding at a dose of 6.0 mg/kg but only 4 of 8 subjects completed the test session thus precluding statistical analysis. Bufotenine (25.8%) also failed to substitute. Although none of the tryptamines substituted completely for LSD, the pattern of substitution is consonant with what is known of their activity in humans. MDMT, DMT, and DET are well established in the literature as hallucinogens but the same cannot be said for 6-F-DET and bufotenine. 3. Of the beta-carbolines tested, none substituted for LSD completely and only harmane elicited intermediate substitution (49.5%). No significant generalization of the LSD stimulus to 6-methoxyharmalan, harmaline, or THBC was observed. Thus, in contrast to the tryptamines, scant ability to substitute for LSD was observed in the beta-carbolines tested. 4. Taken together, the present data indicate that the representative tryptamines employed in the present study exhibit greater similarity to the LSD stimulus than do representative beta-carbolines. The receptor interactions responsible for these differences remain to be determined.
Frandsen, Mai; Dunbar, Michael S.; Shiffman, Saul
Introduction: Gender differences in smoking behavior have been proposed to account for poorer outcomes among women attempting to quit. Specifically, it has been suggested that women’s smoking behavior is less motivated by nicotine-seeking and more driven by environmental cues. To date, however, few real-world studies have examined the hypothesis that women’s smoking is under greater stimulus control. Methods: One hundred and ninety four daily smokers (men = 107; women = 87) completed 3 weeks of ecological momentary assessment (EMA) monitoring that provided data on real-world smoking behavior by reporting on situational contexts shown by previous research to influence smoking behavior (including social setting, cigarette availability, alcohol consumption, and mood). Results: Analyses of particular cues found few gender differences; however, men’s smoking increased to a greater extent compared with women’s when they were with others who were smoking. Idiographic analyses that allow individual subjects to have different directions of linkage to situational cues also were conducted to assess how predictable subjects’ smoking was from a range of contextual characteristics. Compared with women, men’s smoking was significantly more closely tied to food/alcohol consumption and tended to be more closely tied to social context. No other gender differences were found. Conclusions: EMA analyses suggest that men and women are similarly influenced by cues, including mood. Where there were gender differences, it was men rather than women whose smoking behavior was more influenced by cues. The data contradict the hypothesis that women’s smoking is more influenced by cues. PMID:25762752
de Villiers, Peter
In developing a test of pragmatic skills for children ages 4 to 9 years, we focused on a number of functional language skills that are important for children's success in early schooling and for the development of fluent reading and writing. They included (1) wh-question asking, (2) communicative role taking, (3) linking events in a cohesive narrative, and (4) articulating the mental states of the characters in a story. All of the proposed items provide specific referential support and pragmatic motivation for the forms and content to be produced by the child. The pictured materials and elicitation prompts constrain the range of appropriate utterances, so the children's productions are more easily scored than an open-ended spontaneous speech sample. All tasks described show a clear developmental trend, a clear separation between the performance of typically developing and language-impaired children, and no performance differences between African American English- and Mainstream American English-speaking children.
Adam, Frédéric; Bonnet, Francis; Le Bars, Daniel
N-methyl-D-aspartate (NMDA) receptors are widely involved in opioid tolerance. However, it is less clear whether NMDA receptor antagonists reverse already-established tolerance and whether the intensity of the nociceptive stimulus influences morphine tolerance. Three days after implantation of morphine or control pellets the effects of i.v. morphine and pre-administration of saline or (+)-HA966 (a glycine site-specific NMDA receptor antagonist), were studied on the C-fibre reflex elicited by a wide range of stimulus intensities. Morphine both increased the threshold and decreased the slope of the recruitment curve in the "non-tolerant" group of animals. In the "morphine-tolerant" group, the threshold did not change but the gain of the stimulus-response curve decreased. The expression of tolerance to morphine depended on the intensity of the stimulus, being maximal when threshold stimulus intensities were used but considerably less with supra-threshold stimulation. As expected, a single treatment with (+)-HA966, potentiated morphine antinociception in "non-tolerant" rats. However, in "morphine-tolerant" rats (+)-HA966 reversed established morphine tolerance and increased the antinociceptive effects of morphine. These results suggest that (+)-HA966 interfered with expression of morphine tolerance, and offered an encouraging therapeutic approach for pain management in opioid abusers.
Ma, Ning; Yu, Angela J
Inhibitory control, the ability to stop or modify preplanned actions under changing task conditions, is an important component of cognitive functions. Two lines of models of inhibitory control have previously been proposed for human response in the classical stop-signal task, in which subjects must inhibit a default go response upon presentation of an infrequent stop signal: (1) the race model, which posits two independent go and stop processes that race to determine the behavioral outcome, go or stop; and (2) an optimal decision-making model, which posits that observers decides whether and when to go based on continually (Bayesian) updated information about both the go and stop stimuli. In this work, we probe the relationship between go and stop processing by explicitly manipulating the discrimination difficulty of the go stimulus. While the race model assumes the go and stop processes are independent, and therefore go stimulus discriminability should not affect the stop stimulus processing, we simulate the optimal model to show that it predicts harder go discrimination should result in longer go reaction time (RT), lower stop error rate, as well as faster stop-signal RT. We then present novel behavioral data that validate these model predictions. The results thus favor a fundamentally inseparable account of go and stop processing, in a manner consistent with the optimal model, and contradicting the independence assumption of the race model. More broadly, our findings contribute to the growing evidence that the computations underlying inhibitory control are systematically modulated by cognitive influences in a Bayes-optimal manner, thus opening new avenues for interpreting neural responses underlying inhibitory control.
Ma, Ning; Yu, Angela J.
Inhibitory control, the ability to stop or modify preplanned actions under changing task conditions, is an important component of cognitive functions. Two lines of models of inhibitory control have previously been proposed for human response in the classical stop-signal task, in which subjects must inhibit a default go response upon presentation of an infrequent stop signal: (1) the race model, which posits two independent go and stop processes that race to determine the behavioral outcome, go or stop; and (2) an optimal decision-making model, which posits that observers decides whether and when to go based on continually (Bayesian) updated information about both the go and stop stimuli. In this work, we probe the relationship between go and stop processing by explicitly manipulating the discrimination difficulty of the go stimulus. While the race model assumes the go and stop processes are independent, and therefore go stimulus discriminability should not affect the stop stimulus processing, we simulate the optimal model to show that it predicts harder go discrimination should result in longer go reaction time (RT), lower stop error rate, as well as faster stop-signal RT. We then present novel behavioral data that validate these model predictions. The results thus favor a fundamentally inseparable account of go and stop processing, in a manner consistent with the optimal model, and contradicting the independence assumption of the race model. More broadly, our findings contribute to the growing evidence that the computations underlying inhibitory control are systematically modulated by cognitive influences in a Bayes-optimal manner, thus opening new avenues for interpreting neural responses underlying inhibitory control. PMID:27047324
Yamada, Y; Stohler, C S; Shimada, K; Ash, M M
Jaw-opening reflex responses elicited by tapping the chin during maximum clenching in incisal edge-to-edge contact position were studied in 10 healthy subjects. Stimuli were also delivered during weak clenching on a rubber stamp, separating the incisors by approx. 10 mm and protruding the mandible to the edge-to-edge incisor relationship. All four central incisors were stimulated simultaneously. With weak stimuli, there was a short-latency (9.5 ms) digastric response which may have had a disynaptic pathway. Taps of moderate strength produced long-latency (20 ms) responses, and sometimes a short-latency (9.5 ms) component as well. Strong (non-painful) taps produced an even longer-latency digastric response, 30 ms or more following the stimulus with less synchronization than earlier responses. Jaw-jerk reflexes occurred 8.5 ms following the tap, independently of the magnitude of the stimulus. Local anaesthesia of the upper and lower incisors abolished the digastric muscle response. Thus large periodontal afferents may be responsible for the early digastric reflex activity and smaller fibres for later effects. Temporal summation of the reflex response probably occurred when all incisors were stimulated simultaneously.
Jones, Erick; Romero-Ortega, Mario
Anecdotal and clinical reports have suggested that radio-frequency electromagnetic fields (RF EMFs) may serve as a trigger for neuropathic pain. However, these reports have been widely disregarded, as the epidemiological effects of electromagnetic fields have not been systematically proven, and are highly controversial. Here, we demonstrate that anthropogenic RF EMFs elicit post-neurotomy pain in a tibial neuroma transposition model. Behavioral assays indicate a persistent and significant pain response to RF EMFs when compared to SHAM surgery groups. Laser thermometry revealed a transient skin temperature increase during stimulation. Furthermore, immunofluorescence revealed an increased expression of temperature sensitive cation channels (TRPV4) in the neuroma bulb, suggesting that RF EMF-induced pain may be due to cytokine-mediated channel dysregulation and hypersensitization, leading to thermal allodynia. Additional behavioral assays were performed using an infrared heating lamp in place of the RF stimulus. While thermally-induced pain responses were observed, the response frequency and progression did not recapitulate the RF EMF effects. In vitro calcium imaging experiments demonstrated that our RF EMF stimulus is sufficient to directly contribute to the depolarization of dissociated sensory neurons. Furthermore, the perfusion of inflammatory cytokine TNF-α resulted in a significantly higher percentage of active sensory neurons during RF EMF stimulation. These results substantiate patient reports of RF EMF-pain, in the case of peripheral nerve injury, while confirming the public and scientific consensus that anthropogenic RF EMFs engender no adverse sensory effects in the general population. PMID:26760033
Black, Bryan; Granja-Vazquez, Rafael; Johnston, Benjamin R; Jones, Erick; Romero-Ortega, Mario
Anecdotal and clinical reports have suggested that radio-frequency electromagnetic fields (RF EMFs) may serve as a trigger for neuropathic pain. However, these reports have been widely disregarded, as the epidemiological effects of electromagnetic fields have not been systematically proven, and are highly controversial. Here, we demonstrate that anthropogenic RF EMFs elicit post-neurotomy pain in a tibial neuroma transposition model. Behavioral assays indicate a persistent and significant pain response to RF EMFs when compared to SHAM surgery groups. Laser thermometry revealed a transient skin temperature increase during stimulation. Furthermore, immunofluorescence revealed an increased expression of temperature sensitive cation channels (TRPV4) in the neuroma bulb, suggesting that RF EMF-induced pain may be due to cytokine-mediated channel dysregulation and hypersensitization, leading to thermal allodynia. Additional behavioral assays were performed using an infrared heating lamp in place of the RF stimulus. While thermally-induced pain responses were observed, the response frequency and progression did not recapitulate the RF EMF effects. In vitro calcium imaging experiments demonstrated that our RF EMF stimulus is sufficient to directly contribute to the depolarization of dissociated sensory neurons. Furthermore, the perfusion of inflammatory cytokine TNF-α resulted in a significantly higher percentage of active sensory neurons during RF EMF stimulation. These results substantiate patient reports of RF EMF-pain, in the case of peripheral nerve injury, while confirming the public and scientific consensus that anthropogenic RF EMFs engender no adverse sensory effects in the general population.
Machell, David F.
Illustrates the stimulus addiction chain experienced by a substance addicted person and recommends that substance abuse treatment agencies provide low-stimulus activity by controlling their use of high-stimulus structure and high-level recreational stimulus producers. Suggests quiet activities to help regulate stimulus and reinforce reflectiveness…
Rudolph, Erica D; Ells, Emma M L; Campbell, Debra J; Abriel, Shelagh C; Tibbo, Philip G; Salisbury, Dean F; Fisher, Derek J
The mismatch negativity (MMN) is an EEG-derived event-related potential (ERP) elicited by any violation of a predicted auditory 'rule', regardless of whether one is attending to the stimuli, and is thought to reflect updating of the stimulus context. Chronic schizophrenia patients exhibit robust MMN deficits, while MMN reduction in first-episode and early phase psychosis is significantly less consistent. Traditional two-tone "oddball" MMN measures of sensory information processing may be considered too simple for use in early phase psychosis in which pathology has not progressed fully, and a paradigm that probes higher order processes may be more appropriate for elucidating auditory change detection deficits. This study investigated whether MMN deficits could be detected in early phase psychosis (EP) patients using an abstract 'missing stimulus' pattern paradigm (Salisbury, 2012). The stimuli were 400 groups of six tones (1000Hz, 50ms duration, 330ms stimulus onset asynchrony), which was presented with an inter-trial interval of 750ms. Occasionally a group contained a deviant, meaning that it was missing either the 4th or 6th tone (50 trials each). EEG recordings of 13 EP patients (≤5year duration of illness) and 15 healthy controls (HC) were collected. Patients and controls did not significantly differ on age or years of education. Analyses of MMN amplitudes elicited by missing stimuli revealed amplitude reductions in EP patients, suggesting that these deficits are present very early in the progression of the illness. While there were no correlations between MMN measures and measures such as duration of illness, medication dosage or age, MMN amplitude reductions were correlated with positive symptomatology (i.e. auditory hallucinations). These findings suggest that MMNs elicited by the 'missing stimulus' paradigm are impaired in psychosis patients early in the progression of illness and that previously reported MMN-indexed deficits related to auditory
Podlesnik, Christopher A; Kelley, Michael E
Resurgence is the relapse of a previously reinforced and then extinguished target response when extinguishing a more recently reinforced alternative response. We designed the present study to assess the contribution of stimulus-control and reinforcer-control processes in determining resurgence. In a modified resurgence procedure, we removed the alternative discriminative stimulus signaling alternative reinforcement when extinguishing the alternative response. This produced more abrupt resurgence of target responding than in a typical resurgence procedure maintaining the alternative discriminative stimulus when extinguishing the alternative response. The overall amount of resurgence did not differ. Importantly, a "renewal" control added and removed the alternative stimulus during extinction, identically as in the modified resurgence procedure. However, alternative responding was never reinforced, which produced no relapse of target responding. Therefore, the more abrupt resurgence with the modified procedure than with the typical procedure suggests removing the alternative stimulus reduced the competition between alternative and target responding. These findings revealed the importance of adding and removing alternative reinforcement in producing resurgence (reinforcer control) but little influence of simply adding and removing the alternative stimulus (stimulus control). These data suggest that clinicians should consider the long-term availability of the alternative response option when developing differential-reinforcement interventions.
Psychologists in the early years of the discipline were much concerned with the stimulus-error. Roughly, this is the problem encountered in introspective experiments when subjects are liable to frame their perceptual reports in terms of what they know of the stimulus, instead of just drawing on their perceptual experiences as they are supposedly felt. "Introspectionist" psychologist E. B. Titchener and his student E. G. Boring both argued in the early 20th century that the stimulus-error is a serious methodological pit-fall. While many of the theoretical suppositions motivating Titchener and Boring have been unfashionable since the rise of behaviourism, the stimulus-error brings our attention to one matter of perennial importance to psychophysics and the psychology of perception. This is the fact that subjects are liable to give different kinds of perceptual reports in response to the same stimulus. I discuss attempts to control for variable reports in recent experimental work on colour and lightness constancy, and the disputes that have arisen over which kinds of reports are legitimate. Some contemporary psychologists do warn us against a stimulus-error, even though they do not use this terminology. I argue that concern over the stimulus-error is diagnostic of psychologists' deep theoretical commitments, such as their conception of sensation, or their demarcation of perception from cognition. I conclude by discussing the relevance of this debate to current philosophy of perception.
Gan, Liu Shi; Ravid, Einat N; Kowalczewski, Jan; Gauthier, Michel; Olson, Jaret; Morhart, Michael; Prochazka, Arthur
Neuroprostheses (NPs) are electrical stimulators that help to restore sensory or motor functions lost as a result of neural damage. The Stimulus Router System (SRS) is a new type of NP developed in our laboratory. The system uses fully implanted, passive leads to "capture" and "route" some of the current flowing between pairs of surface electrodes to the vicinity of the target nerves, hence eliminating the need for an implanted stimulator. In June 2008, 3 SRS leads were implanted in a tetraplegic man for restoration of grasp and release. To reduce the size of the external wristlet and thereby optimize usability, we recently implemented a polarity reversing stimulation technique that allowed us to eliminate a reference electrode. Selective activation of three target muscles was achieved by switching the polarities of the stimulus current delivered between pairs of surface electrodes located over the pick-up terminals of the implanted leads and reducing the amplitude of the secondary phases of the stimulus pulses.
Jinks, Steven L.; Bravo, Milo; Hayes, Shawn G.
Background Volatile anesthetics produce immobility primarily by action in the spinal cord; however, anesthetic effects among different neuronal classes located in different spinal regions, and how they relate to immobility, are not understood. Methods In decerebrated rats, effects of isoflurane and halothane on movement elicited by electrical microstimulation of the mesencephalic locomotor region (MLR) were assessed in relation to minimum alveolar concentration (MAC). Anesthetic effects on step frequency and isometric limb force were measured. The authors also examined effects of MLR stimulation on responses of nociceptive dorsal horn neurons and limb force responses to tail clamp. Results Mean isoflurane requirements to block MLR-elicited stepping were slightly but significantly greater than MAC by 10%. Mean halothane requirements to block MLR-elicited stepping were greater than those for isoflurane and exceeded MAC by 20%. From 0.4 to 1.3 MAC (but not 0.0 to 0.4 MAC), there was a dose-dependent reduction in the frequency and force of hind limb movements elicited by MLR stimulation during both anesthetics. MLR stimulation inhibited noxious stimulus evoked responses of dorsal horn neurons by approximately 80%. Aptly, MLR stimulation produced analgesia that outlasted the midbrain stimulus by at least 15 s, as indicated by an 81% reduction in hind limb force elicited noxious tail clamp. Conclusions Because electrical stimulation of the MLR elicits movement independent of dorsal horn activation, the results suggest that the immobilizing properties of isoflurane and halothane are largely independent of action in the dorsal horn. The results suggest that volatile anesthetics produce immobility mainly by action on ventral spinal locomotor networks. PMID:18497602
Fried, Shelley I.; Cai, Changsi; Ren, Qiushi
The effectiveness of retinal prosthetics will depend on their ability to elicit patterns of neural activity that can be recognized by the visual cortex. While conventional short-duration pulses activate retinal neurons effectively, many nearby neurons are thought to respond similarly to a given pulse train – a situation that is non-physiological. Use of pulse trains delivered at rates > 1000 pulses per second (PPS) in cochlear prosthetics help to avoid phase-locked responses but have not been evaluated in the retina; here, we explored the response to trains of 2000 PPS. We found that ganglion cells respond robustly to these stimuli but that the properties of the response were highly sensitive to stimulus amplitude. At low amplitudes the response patterns were burst-like while at higher amplitudes elicited spikes had intervals that were more uniform. Because burst responses were insensitive to synaptic blockers, our results suggest that they arise from direct activation. This was surprising because previous studies indicated that burst responses arise only through indirect activation. Thus, our results suggest multiple mechanisms of burst creation may exist. Further, histograms of interspike intervals revealed that the response properties were different in different types of ganglion cells. While further testing is needed, the ability to create different patterns of activity in different types of ganglion cells raises the possibility that more natural spike patterns can be created. PMID:22254500
Fujimura, Tomomi; Okanoya, Kazuo
The ability to detect emotional change in the environment is essential for adaptive behavior. The current study investigated whether event-related potentials (ERPs) can reflect emotional change in a visual sequence. To assess pre-attentive processing, we examined visual mismatch negativity (vMMN): the negative potentials elicited by a deviant (infrequent) stimulus embedded in a sequence of standard (frequent) stimuli. Participants in two experiments pre-attentively viewed visual sequences of Japanese kanji with different emotional connotations while ERPs were recorded. The visual sequence in Experiment 1 consisted of neutral standards and two types of emotional deviants with a strong and weak intensity. Although the results indicated that strongly emotional deviants elicited more occipital negativity than neutral standards, it was unclear whether these negativities were derived from emotional deviation in the sequence or from the emotional significance of the deviants themselves. In Experiment 2, the two identical emotional deviants were presented against different emotional standards. One type of deviants was emotionally incongruent with the standard and the other type of deviants was emotionally congruent with the standard. The results indicated that occipital negativities elicited by deviants resulted from perceptual changes in a visual sequence at a latency of 100–200 ms and from emotional changes at latencies of 200–260 ms. Contrary to the results of the ERP experiment, reaction times to deviants showed no effect of emotional context; negative stimuli were consistently detected more rapidly than were positive stimuli. Taken together, the results suggest that brain signals can reflect emotional change in a temporal context. PMID:23671693
Decety, Jean; Skelly, Laurie R.; Kiehl, Kent A.
Context A marked lack of empathy is a hallmark characteristic of individuals with psychopathy. However, neural response associated to empathic processing has not yet been directly examined in psychopathy especially in response to the perception of other people in pain and distress. Objective To identify potential differences in patterns of neural activity in incarcerated psychopaths and incarcerated controls during the perception of empathy-eliciting stimuli depicting other people in pain. Design In a case-control study, brain activation patterns elicited by dynamic stimuli depicting individuals being harmed and facial expression of pain were compared between incarcerated psychopaths and incarcerated controls. Setting Participants were scanned in on the grounds of a correctional facility using the Mind Research Network's mobile 1.5 T MRI system. Participants Eighty incarcerated males were classified according to scores on the Hare Psychopathy Checklist-Revised (PCL-R) as high (n = 27; PCL-R =30), intermediate (n = 28; PCL-R between 21–29), or low (n = 25; PCL-R ≤20) on psychopathy. Main Outcome Measure Neuro-hemodynamic response to empathy-eliciting dynamic scenarios revealed by functional magnetic resonance imaging. Results Psychopaths exhibited significantly less activation in the ventromedial prefrontal cortex, lateral orbitofrontal cortex, and periaqueductal gray relative to controls, but showed greater activation in the insula. Conclusion In response to pain cues expressed by others, psychopaths exhibit deficits in vmPFC and OFC regardless of stimulus type, but display selective impairment in processing facial cues of distress in regions associated with cognitive mentalizing. PMID:23615636
Fleishman, Erica; Burgman, Mark; Runge, Michael C.; Schick, Robert S; Krauss, Scott; Popper, Arthur N.; Hawkins, Anthony
Expert elicitation is a rigorous method for synthesizing expert knowledge to inform decision making and is reliable and practical when field data are limited. We evaluated the feasibility of applying expert elicitation to estimate population-level effects of disturbance on marine mammals. Diverse experts estimated parameters related to mortality and sublethal injury of North Atlantic right whales (Eubalaena glacialis). We are now eliciting expert knowledge on the movement of right whales among geographic regions to parameterize a spatial model of health. Expert elicitation complements methods such as simulation models or extrapolations from other species, sometimes with greater accuracy and less uncertainty.
Fleishman, Erica; Burgman, Mark; Runge, Michael C; Schick, Robert S; Kraus, Scott
Expert elicitation is a rigorous method for synthesizing expert knowledge to inform decision making and is reliable and practical when field data are limited. We evaluated the feasibility of applying expert elicitation to estimate population-level effects of disturbance on marine mammals. Diverse experts estimated parameters related to mortality and sublethal injury of North Atlantic right whales (Eubalaena glacialis). We are now eliciting expert knowledge on the movement of right whales among geographic regions to parameterize a spatial model of health. Expert elicitation complements methods such as simulation models or extrapolations from other species, sometimes with greater accuracy and less uncertainty.
Klingner, Carsten M; Hasler, Caroline; Brodoehl, Stefan; Witte, Otto W
The primary somatosensory cortex (SI) has been shown to encode the intensity of a stimulus applied to the contralateral side of the body. Recent studies have demonstrated that ipsilateral SI is also involved in the processing of somatosensory information. In this study, we investigated the dependence of the negative BOLD response in ipsilateral SI on the intensity of somatosensory stimulation. Functional MRI was performed in 12 healthy subjects during electrical median nerve stimulation at four different intensities. A monotonic relationship between stimulus intensity and the strength of the negative BOLD response in ipsilateral SI was found. Additionally, a psychophysiological experiment revealed tight coupling between the stimulus intensity applied to one hand and increased perceptual threshold of the other hand. These findings indicate a stimulus intensity-dependent inhibition of ipsilateral SI.
Gehring, W. J.; Gratton, G.; Coles, M. G.; Donchin, E.
This study investigated the effects of probability information on response preparation and stimulus evaluation. Eight subjects responded with one hand to the target letter H and with the other to the target letter S. The target letter was surrounded by noise letters that were either the same as or different from the target letter. In 2 conditions, the targets were preceded by a warning stimulus unrelated to the target letter. In 2 other conditions, a warning letter predicted that the same letter or the opposite letter would appear as the imperative stimulus with .80 probability. Correct reaction times were faster and error rates were lower when imperative stimuli confirmed the predictions of the warning stimulus. Probability information affected (a) the preparation of motor responses during the foreperiod, (b) the development of expectancies for a particular target letter, and (c) a process sensitive to the identities of letter stimuli but not to their locations.
Washburn, David A.
In previous reports, including one by the author, learning has been shown to benefit by having discriminanda move rather than remain stationary. This stimulus movement effect might be attributed to several theoretical mechanisms, including attention, topological memory, and exposure duration. The series of experiments reported in this article was designed to Contrast these potential explanatory factors. Ten rhesus monkeys (Macaca mulatta) were tested on a variety of computerized tasks in which the stimuli remained stationary, flashed, or moved at systematically varied speeds. Performance was significantly best when the sample stimulus moved quickly and was poorest when the stimulus remained stationary. Further analysis of these data and other previously published data revealed that the distribution of the stimulus movement effect across trials supported an attention allocation interpretation.
Alvarez, Manuel; Zainos, Antonio; Romo, Ranulfo
Neurons of the primary somatosensory cortex (S1) respond as functions of frequency or amplitude of a vibrotactile stimulus. However, whether S1 neurons encode both frequency and amplitude of the vibrotactile stimulus or whether each sensory feature is encoded by separate populations of S1 neurons is not known, To further address these questions, we recorded S1 neurons while trained monkeys categorized only one sensory feature of the vibrotactile stimulus: frequency, amplitude, or duration. The results suggest a hierarchical encoding scheme in S1: from neurons that encode all sensory features of the vibrotactile stimulus to neurons that encode only one sensory feature. We hypothesize that the dynamic representation of each sensory feature in S1 might serve for further downstream processing that leads to the monkey’s psychophysical behavior observed in these tasks. PMID:25825711
Doughty, Adam H; Kastner, Rebecca M; Bismark, Bryan D
Resurgence typically refers to the recovery of a previously reinforced response when a more recently reinforced response is extinguished. Under conditions of punishment, Wilson and Hayes (1996) observed the recovery of derived stimulus relations that never had been correlated with differential consequences. The present study systematically replicated the findings of Wilson and Hayes by observing the recovery of derived stimulus relations under extinction conditions and with an additional equivalence class. College students received arbitrary-matching-to-sample training in Phase 1 that resulted in four 4-member stimulus-equivalence classes. These derived relations were not correlated with differential consequences. In Phase 2, with the same stimuli, the students received training that resulted in four different 4-member stimulus-equivalence classes. After the emergence and reinforcement of the latter derived relations, their extinction generated the recurrence of the derived relations from Phase 1. The implications of these findings for conceptualizing resurgence are discussed.
Ramsey, Richard; Liepelt, Roman; Prinz, Wolfgang; Hamilton, Antonia F. de C.
Although robots are becoming an ever-growing presence in society, we do not hold the same expectations for robots as we do for humans, nor do we treat them the same. As such, the ability to recognize cues to human animacy is fundamental for guiding social interactions. We review literature that demonstrates cortical networks associated with person perception, action observation and mentalizing are sensitive to human animacy information. In addition, we show that most prior research has explored stimulus properties of artificial agents (humanness of appearance or motion), with less investigation into knowledge cues (whether an agent is believed to have human or artificial origins). Therefore, currently little is known about the relationship between stimulus and knowledge cues to human animacy in terms of cognitive and brain mechanisms. Using fMRI, an elaborate belief manipulation, and human and robot avatars, we found that knowledge cues to human animacy modulate engagement of person perception and mentalizing networks, while stimulus cues to human animacy had less impact on social brain networks. These findings demonstrate that self–other similarities are not only grounded in physical features but are also shaped by prior knowledge. More broadly, as artificial agents fulfil increasingly social roles, a challenge for roboticists will be to manage the impact of pre-conceived beliefs while optimizing human-like design. PMID:26644594
Cross, Emily S; Ramsey, Richard; Liepelt, Roman; Prinz, Wolfgang; de C Hamilton, Antonia F
Although robots are becoming an ever-growing presence in society, we do not hold the same expectations for robots as we do for humans, nor do we treat them the same. As such, the ability to recognize cues to human animacy is fundamental for guiding social interactions. We review literature that demonstrates cortical networks associated with person perception, action observation and mentalizing are sensitive to human animacy information. In addition, we show that most prior research has explored stimulus properties of artificial agents (humanness of appearance or motion), with less investigation into knowledge cues (whether an agent is believed to have human or artificial origins). Therefore, currently little is known about the relationship between stimulus and knowledge cues to human animacy in terms of cognitive and brain mechanisms. Using fMRI, an elaborate belief manipulation, and human and robot avatars, we found that knowledge cues to human animacy modulate engagement of person perception and mentalizing networks, while stimulus cues to human animacy had less impact on social brain networks. These findings demonstrate that self-other similarities are not only grounded in physical features but are also shaped by prior knowledge. More broadly, as artificial agents fulfil increasingly social roles, a challenge for roboticists will be to manage the impact of pre-conceived beliefs while optimizing human-like design.
Dickson, Chata A; Wang, Sharon S; Lombard, Kristin M; Dube, William V
Overselective stimulus control was assessed in 29 students at residential schools for individuals with developmental disabilities. Overselectivity testing included three different delayed identity matching-to-sample tasks. Sample stimuli for the Form/Color Test were nine possible combinations of three colors and three forms. On each trial, the S+ stimulus was identical to the sample, one S- was the same color as the sample but a different form, and the other S- was the same form but a different color. Sample stimuli for the Two-Sample Test were two alphanumeric characters. The S+ stimulus was identical to one of the sample stimuli, and two S- stimuli were characters different from both samples. Sample stimuli for the Faces Test were six digital images of adult faces. On each trial, the S+ stimulus was identical to the sample, one S- stimulus was a non-matching face to which one sample feature had been added (e.g., an identical hat or scarf), and the other S- stimulus was an unaltered non-matching face. All participants were also tested with the Peabody Picture Vocabulary Test III (PPVT) and the Autism Diagnostic Observation Schedule (ADOS). Results indicated overselective stimulus control on at least one test for 18 of the 29 participants. Overselectivity (a) was distributed across a range of PPVT mental age equivalent scores from <1.75 to 8.83; (b) was more likely in individuals with higher ADOS scores; (c) was most likely on the Two-Sample Test; and (d) was found in five individuals on more than one of the tests. Thus, overselective stimulus control may occur across a range of characteristics typical for students who attend residential special-education programs.
MULTIPLE COLOR STIMULUS INDUCED STEADY STATE VISUAL EVOKED POTENTIALS M. Cheng, X. Gao, S. Gao, D. Xu Institute of Biomedical Engineering...characteristics of high SNR and effectiveness in short-term identification of evoked responses. In most of the SSVEP experiments, single high...frequency stimuli are used. To characterize the complex rhythms in SSVEP, a new multiple color stimulus pattern is proposed in this paper. FFT and
Crane, Benjamin T.
A theme in sensory perception it that exposure to a stimulus causes perception of subsequent stimuli to be shifted in the opposite direction. Such phenomenon are known as aftereffects and have been extensively described in the visual system as well as recently described for the vestibular system during translation. It is known from aviation studies that after a maneuver in roll pilots can experience a false perception of roll in the opposite direction. The magnitude and duration of this effect as well as the potential influence of the gravity vector have not previously been defined. In the current paper this roll aftereffect (RAE) is examined in response to whole body roll about an earth-horizontal axis in eight healthy human subjects. The peak velocity of a 0.5 s duration roll was varied based on previous responses to find the point where subjects perceived no motion. Without an preceding stimulus the starting position (upright, 9° left, or 9° right) did not influence roll perception. The RAE was measured in a completely dark room using an adapting (firstinterval) stimulus consisting of 9° of roll over 1.5 s (peak velocity 12°/s), delivered 0.5, 3, or 6s prior to test (second-interval) stimulus. A significant RAE was seen in all subjects. Half a second after the adapting stimulus a test stimulus had to be on average 1.5 ± 0.4°/s in the opposite direction to be perceived as stationary. When the subject remained upright after the adapting stimulus the RAE diminished with time, although it remained significantly larger at 3s and 6s when the subject remained tilted after the adapting stimulus. These data demonstrate that roll perception can be influenced by small preceding stimuli and tilt causes a persistence of the RAE. PMID:22945611
The expression of uncertainty has hitherto been seen as an add-on—first an estimate is obtained and then uncertainty in that estimate is evaluated. We argue that quantification of uncertainty should be an intrinsic part of measurement and that the measurement result should be a probability distribution for the measurand. Full quantification of uncertainties in measurement, recognizing and quantifying all sources of uncertainty, is rarely simple. Many potential sources of uncertainty can effectively only be quantified by the application of expert judgement. Scepticism about the validity or reliability of expert judgement has meant that these sources of uncertainty have often been overlooked, ignored or treated in a qualitative, narrative way. But the consequence of this is that reported expressions of uncertainty regularly understate the true degree of uncertainty in measurements. This article first discusses the concept of quantifying uncertainty in measurement, and then considers some of the areas where expert judgement is needed in order to quantify fully the uncertainties in measurement. The remainder of the article is devoted to describing methodology for eliciting expert knowledge.
Croy, Ilona; Olgun, Selda; Joraschky, Peter
The sense of olfaction is often reported to have a special relationship with emotional processing. Memories triggered by olfactory cues often have a very emotional load. On the other hand, basic negative or positive emotional states should be sufficient to cover the most significant functions of the olfactory system including ingestion, hazard avoidance, and social communication. Thus, we investigated whether different basic emotions can be evoked in healthy people through the sense of olfaction. We asked 119 participants which odor evokes one of the six basic emotions (happiness, disgust, anger, anxiety, sadness, and surprise); another 97 participants were asked about pictures evoking those emotions. The results showed that almost every participant could name an olfactory elicitor for happiness or disgust. Olfactory elicitors of anxiety were reported less frequently, but they were still reported by three-quarters of the participants. However, for sadness and anger only about half of the participants reported an olfactory elicitor, whereas significantly more named a visual cue. Olfactory emotion elicitors were mainly related to the classes of culture, plants, and food, and visual emotion elicitors were largely related to humans. This data supports the hypothesis that in the vast majority of people, few differentiated emotions can be elicited through the olfactory channel. These emotions are happiness, disgust, and anxiety.
Taufik, Danny; Bolderdijk, Jan Willem; Steg, Linda
Environmental policies are often based on the assumption that people only act environmentally friendly if some extrinsic reward is implicated, usually money. We argue that people might also be motivated by intrinsic rewards: doing the right thing (such as acting environmentally friendly) elicits psychological rewards in the form of positive feelings, a phenomenon known as warm glow. Given the fact that people's psychological state may affect their thermal state, we expected that this warm glow could express itself quite literally: people who act environmentally friendly may perceive the temperature to be higher. In two studies, we found that people who learned they acted environmentally friendly perceived a higher temperature than people who learned they acted environmentally unfriendly. The underlying psychological mechanism pertains to the self-concept: learning you acted environmentally friendly signals to yourself that you are a good person. Together, our studies show that acting environmentally friendly can be psychologically rewarding, suggesting that appealing to intrinsic rewards can be an alternative way to encourage pro-environmental actions.
Jonas Brännström, K; Nilsson, Patrik
The octave or Deutsch illusion occurs when two tones, separated by about one octave, are presented simultaneously but alternating between ears, such that when the low tone is presented to the left ear the high tone is presented to the right ear and vice versa. Most subjects hear a single tone that alternates both between ears and in pitch; i.e., they hear a low pitched tone in one ear alternating with a high pitched tone in the other ear. The present study examined whether the illusion can be elicited by aperiodic signals consisting of low-frequency band-pass filtered noises with overlapping spectra. The amount of spectral overlap was held constant, but the high- and low-frequency content of the signals was systematically varied. The majority of subjects perceived an auditory illusion in terms of a dominant ear for pitch and lateralization by frequency, as proposed by Deutsch [(1975a) Sci. Am. 233, 92-104]. Furthermore, the salience of the illusion increased as the high frequency of the content in the signal increased. Since no harmonics were present in the stimuli, it is highly unlikely that this illusion is perceived on the basis of binaural diplacusis or harmonic binaural fusion.
Johnson, Tiffany A.; Beshaler, Laura
The present study evaluated the influence of suppressor frequency (fs) and level (Ls) on stimulus-frequency otoacoustic emissions (SFOAEs) recorded using the amplitude-modulated (AM) suppressor technique described by Neely et al. [J. Acoust. Soc. Am. 118, 2124-2127 (2005a)]. Data were collected in normal-hearing subjects, with data collection occurring in two phases. In phase 1, SFOAEs were recorded with probe frequency (fp) = 1, 2, and 4 kHz and probe levels (Lp) ranging from 0 to 60 dB sound pressure level (SPL). At each fp, Ls ranged from Ls = Lp to Ls = Lp + 30 dB. Additionally, nine relationships between fs and fp were evaluated, ranging from fs/fp = 0.80 to fs/fp = 1.16. Results indicated that for low suppressor levels, suppressors higher in frequency than fp (fs > fp) resulted in higher AM-SFOAE levels than suppressors lower in frequency than fp (fs < fp). At higher suppressor levels, suppressors both higher and lower in frequency than fp produced similar AM-SFOAE levels, and, in many cases, low-frequency suppressors produced the largest response. Recommendations for stimulus parameters that maximize AM-SFOAE level were derived from these data. In phase 2, AM-SFOAEs were recorded using these parameters for fp = 0.7-8 kHz and Lp = 20-60 dB SPL. Robust AM-SFOAE responses were recorded in this group of subjects using the parameters developed in phase 1. PMID:23927112
Sztarker, Julieta; Tomsic, Daniel
When confronted with predators, animals are forced to take crucial decisions such as the timing and manner of escape. In the case of the crab Chasmagnathus, cumulative evidence suggests that the escape response to a visual danger stimulus (VDS) can be accounted for by the response of a group of lobula giant (LG) neurons. To further investigate this hypothesis, we examined the relationship between behavioral and neuronal activities within a variety of experimental conditions that affected the level of escape. The intensity of the escape response to VDS was influenced by seasonal variations, changes in stimulus features, and whether the crab perceived stimuli monocularly or binocularly. These experimental conditions consistently affected the response of LG neurons in a way that closely matched the effects observed at the behavioral level. In other words, the intensity of the stimulus-elicited spike activity of LG neurons faithfully reflected the intensity of the escape response. These results support the idea that the LG neurons from the lobula of crabs are deeply involved in the decision for escaping from VDS.
According to contemporary learning theory, drug-seeking behavior reflects the summation of 2 dissociable controllers. Whereas goal-directed drug-seeking is determined by the expected current incentive value of the drug, stimulus-elicited drug-seeking is determined by the expected probability of the drug independently of its current incentive value, and these 2 controllers contribute additively to observed drug-seeking. One applied prediction of this model is that smoking cessation pharmacotherapies selectively attenuate tonic but not cue-elicited craving because they downgrade the expected incentive value of the drug but leave expected probability intact. To test this, the current study examined whether nicotine replacement therapy (NRT) nasal spray would modify goal-directed tobacco choice in a human outcome devaluation procedure, but leave cue-elicited tobacco choice in a Pavlovian to instrumental transfer (PIT) procedure intact. Smokers (N= 96) first underwent concurrent choice training in which 2 responses earned tobacco or chocolate points, respectively. Participants then ingested either NRT nasal spray (1 mg) or chocolate (147 g) to devalue 1 outcome. Concurrent choice was then tested again in extinction to measure goal-directed control of choice, and in a PIT test to measure the extent to which tobacco and chocolate stimuli enhanced choice of the same outcome. It was found that NRT modified tobacco choice in the extinction test but not the extent to which the tobacco stimulus enhanced choice of the tobacco outcome in the PIT test. This dissociation suggests that the propensity to engage in drug-seeking is determined independently by the expected value and probability of the drug, and that pharmacotherapy has partial efficacy because it selectively effects expected drug value.
MATHEWSON, ROBERT H.; ORTON, JOHN W.
THIS STUDY WAS CONDUCTED TO (1) PRODUCE AN INSTRUMENT FOR ELICITING VOCATIONAL IMAGERY FOR USE IN THE EDUCATIONAL-VOCATIONAL ORIENTATION AND COUNSELING OF HIGH SCHOOL YOUTH, AND (2) DEVELOP A SCALE FOR EVALUATING THE MATURITY OF THE VOCATIONAL IMAGERY ELICITED BY THE INSTRUMENT. A PREVIOUSLY DESIGNED INSTRUMENT "WHAT I THINK OF MYSELF"…
Estes, Zachary; Verges, Michelle
Humans preferentially attend to negative stimuli. A consequence of this automatic vigilance for negative valence is that negative words elicit slower responses than neutral or positive words on a host of cognitive tasks. Some researchers have speculated that negative stimuli elicit a general suppression of motor activity, akin to the freezing…
Cornejo, Ricardo J.; And Others
Intended to provide practical information pertaining to methods and techniques for speech elicitation and production, the monograph offers specific methods and techniques to elicit spontaneous speech in bilingual students. Chapter 1, "Traditional Methodologies for Language Production and Recording," presents an overview of studies using…
Eliciting and advocating the voice of the child remains at the heart of international political agenda and also remains a central role for educational psychologists (EPs). Previous research indicates that EPs tend to use language-based methods for eliciting and advocating views of children. However, these approaches are often limited. Taking a…
classroom training as part of leadership development programs. ELICIT is particularly helpful in teaching the strengths and weakness of various...organizational structures (edge organization vs. traditional command and control hierarchy.) This paper reviews some of the pedagogical uses of the classroom ...training to date, and provides recommendations for the use of ELICIT in various classroom settings. 15. SUBJECT TERMS 16. SECURITY CLASSIFICATION OF
Blau, Rivka; Klein, Pnina S.
In this study, the effects of eliciting positive and negative emotions on various cognitive functions of four- to five-year-old preschool children were examined. Emotions were elicited through presentations of "happy" and "sad" video clips, before the children performed the cognitive tasks. Behavioural (facial expressions) and…
Saladin, Michael E; Brady, Kathleen T; Graap, Ken; Rothbaum, Barbara Olasov
In the present feasibility study, we developed a 3-dimensional virtual "crack" cocaine environment and evaluated the environment's ability to elicit subjective craving and cue reactivity (i.e., subjective emotional responding, heart rate and skin conductance) in 11 crack cocaine dependent individuals. Each of the seven 3-D crack cocaine scenes in the cocaine environment depicted actors engaging in a range of using-related behaviors (i.e., smoking crack) whereas the neutral environment contained scenes depicted 3-D aquariums with active aquatic life (baseline measures were obtained following immersion in the neutral environment). Results indicated that craving was significantly elevated during the cocaine-related scenes as compared to baseline. Craving varied by scene content, with scenes depicting active cocaine use eliciting the highest levels of craving. Heart rate was significantly higher in four of the scenes with drug use content and positive affect (i.e., happiness) ratings were significantly lower during cocaine scenes as compared to baseline. Overall, the results suggest that a standardized and stimulus rich virtual reality environment effectively elicits craving and physiologic reactivity. Such technology has potential utility in the development and refinement of exposure-based behavioral and pharmacological interventions for substance use disorders.
Walentiny, D Matthew; Vann, Robert E; Wiley, Jenny L
A number of studies have examined the ability of the endogenous cannabinoid anandamide to elicit Δ(9)-tetrahydrocannabinol (THC)-like subjective effects, as modeled through the THC discrimination paradigm. In the present study, we compared transgenic mice lacking fatty acid amide hydrolase (FAAH), the enzyme primarily responsible for anandamide catabolism, to wildtype counterparts in a THC discrimination procedure. THC (5.6 mg/kg) served as a discriminative stimulus in both genotypes, with similar THC dose-response curves between groups. Anandamide fully substituted for THC in FAAH knockout, but not wildtype, mice. Conversely, the metabolically stable anandamide analog O-1812 fully substituted in both groups, but was more potent in knockouts. The CB1 receptor antagonist rimonabant dose-dependently attenuated THC generalization in both groups and anandamide substitution in FAAH knockouts. Pharmacological inhibition of monoacylglycerol lipase (MAGL), the primary catabolic enzyme for the endocannabinoid 2-arachidonoylglycerol (2-AG), with JZL184 resulted in full substitution for THC in FAAH knockout mice and nearly full substitution in wildtypes. Quantification of brain endocannabinoid levels revealed expected elevations in anandamide in FAAH knockout mice compared to wildtypes and equipotent dose-dependent elevations in 2-AG following JZL184 administration. Dual inhibition of FAAH and MAGL with JZL195 resulted in roughly equipotent increases in THC-appropriate responding in both groups. While the notable similarity in THC's discriminative stimulus effects across genotype suggests that the increased baseline brain anandamide levels (as seen in FAAH knockout mice) do not alter THC's subjective effects, FAAH knockout mice are more sensitive to the THC-like effects of pharmacologically induced increases in anandamide and MAGL inhibition (e.g., JZL184).
This study is one in a series that has examined factors contributing to vowel perception in everyday listening. Four experimental variables have been manipulated to examine systematical differences between optimal laboratory testing conditions and those characterizing everyday listening. These include length of phonetic context, level of stimulus uncertainty, linguistic meaning, and amount of subject training. The present study investigated the effects of stimulus uncertainty from minimal to high uncertainty in two phonetic contexts, /V/ or /bVd/, when listeners had either little or extensive training. Thresholds for discriminating a small change in a formant for synthetic female vowels /I,E,ae,a,inverted v,o/ were obtained using adaptive tracking procedures. Experiment I optimized extensive training for five listeners by beginning under minimal uncertainty (only one formant tested per block) and then increasing uncertainty from 8-to-16-to-22 formants per block. Effects of higher uncertainty were less than expected; performance only decreased by about 30%. Thresholds for CVCs were 25% poorer than for isolated vowels. A previous study using similar stimuli [Kewley-Port and Zheng. J. Acoust. Soc. Am. 106, 2945-2958 (1999)] determined that the ability to discriminate formants was degraded by longer phonetic context. A comparison of those results with the present ones indicates that longer phonetic context degrades formant frequency discrimination more than higher levels of stimulus uncertainty. In experiment 2, performance in the 22-formant condition was tracked over 1 h for 37 typical listeners without formal laboratory training. Performance for typical listeners was initially about 230% worse than for trained listeners. Individual listeners' performance ranged widely with some listeners occasionally achieving performance similar to that of the trained listeners in just one hour.
Rosenthal, Gideon; Sporns, Olaf; Avidan, Galia
Using the "face inversion effect", a hallmark of face perception, we examined network mechanisms supporting face representation by tracking functional magnetic resonance imaging (fMRI) stimulus-dependent dynamic functional connectivity within and between brain networks associated with the processing of upright and inverted faces. We developed a novel approach adapting the general linear model (GLM) framework classically used for univariate fMRI analysis to capture stimulus-dependent fMRI dynamic connectivity of the face network. We show that under the face inversion manipulation, the face and non-face networks have complementary roles that are evident in their stimulus-dependent dynamic connectivity patterns as assessed by network decomposition into components or communities. Moreover, we show that connectivity patterns are associated with the behavioral face inversion effect. Thus, we establish "a network-level signature" of the face inversion effect and demonstrate how a simple physical transformation of the face stimulus induces a dramatic functional reorganization across related brain networks. Finally, we suggest that the dynamic GLM network analysis approach, developed here for the face network, provides a general framework for modeling the dynamics of blocked stimulus-dependent connectivity experimental designs and hence can be applied to a host of neuroimaging studies.
Weller, Richard E [Selah, WA; Lind, Michael A [Kent, WA; Fisher, Darrell R [Richland, WA; Gutowska, Anna [Richland, WA; Campbell, Allison A [Kennewick, WA
The present invention is a thermally reversible stimulus-sensitive gel or gelling copolymer radioisotope carrier that is a linear random copolymer of an [meth]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum gelling molecular weight cutoff. Addition of a biodegradable backbone and/or a therapeutic agent imparts further utility. The method of the present invention for making a thermally reversible stimulus-sensitive gelling copolymer radionuclcide carrier has the steps of: (a) mixing a stimulus-sensitive reversible gelling copolymer with an aqueous solvent as a stimulus-sensitive reversible gelling solution; and (b) mixing a radioisotope with said stimulus-sensitive reversible gelling solution as said radioisotope carrier. The gel is enhanced by either combining it with a biodegradable backbone and/or a therapeutic agent in a gelling solution made by mixing the copolymer with an aqueous solvent.
Weller, Richard E.; Lind, Michael A.; Fisher, Darrell R.; Gutowska, Anna; Campbell, Allison A.
The present invention is a thermally reversible stimulus-sensitive gel or gelling copolymer radioisotope carrier that is a linear random copolymer of an [meth-]acrylamide derivative and a hydrophilic comonomer, wherein the linear random copolymer is in the form of a plurality of linear chains having a plurality of molecular weights greater than or equal to a minimum gelling molecular weight cutoff. Addition of a biodegradable backbone and/or a therapeutic agent imparts further utility. The method of the present invention for making a thermally reversible stimulus-sensitive gelling copolymer radionuclcide carrier has the steps of: (a) mixing a stimulus-sensitive reversible gelling copolymer with an aqueous solvent as a stimulus-sensitive reversible gelling solution; and (b) mixing a radioisotope with said stimulus-sensitive reversible gelling solution as said radioisotope carrier. The gel is enhanced by either combining it with a biodegradable backbone and/or a therapeutic agent in a gelling solution made by mixing the copolymer with an aqueous solvent.
Larsson, Jonas; Smith, Andrew T
Measurements of repetition suppression with functional magnetic resonance imaging (fMRI adaptation) have been used widely to probe neuronal population response properties in human cerebral cortex. fMRI adaptation techniques assume that fMRI repetition suppression reflects neuronal adaptation, an assumption that has been challenged on the basis of evidence that repetition-related response changes may reflect unrelated factors, such as attention and stimulus expectation. Specifically, Summerfield et al. (Summerfield C, Trittschuh EH, Monti JM, Mesulam MM, Egner T. 2008. Neural repetition suppression reflects fulfilled perceptual expectations. Nat Neurosci. 11:1004-1006) reported that the relative frequency of stimulus repetitions and non-repetitions influenced the magnitude of repetition suppression in the fusiform face area, suggesting that stimulus expectation accounted for most of the effect of repetition. We confirm that stimulus expectation can significantly influence fMRI repetition suppression throughout visual cortex and show that it occurs with long as well as short adaptation durations. However, the effect was attention dependent: When attention was diverted away from the stimuli, the effects of stimulus expectation completely disappeared. Nonetheless, robust and significant repetition suppression was still evident. These results suggest that fMRI repetition suppression reflects a combination of neuronal adaptation and attention-dependent expectation effects that can be experimentally dissociated. This implies that with an appropriate experimental design, fMRI adaptation can provide valid measures of neuronal adaptation and hence response specificity.
Metzger, Mitchell M; Riccio, David C
Numerous studies have demonstrated that the forgetting of stimulus attributes is a common occurrence; that is, organisms forget the specific characteristics of training stimuli over long retention intervals, while retaining general information of the training stimuli themselves. However, most studies have examined this effect after a learning episode, and there have been virtually no accounts to test whether the forgetting of attributes occurs for stimuli presented prior to training. Therefore, this experiment was designed to test that possibility, and it examined whether the forgetting of stimulus attributes occurred prior to training for the flavor stimulus in a conditioned taste aversion (CTA) procedure. Specifically, a latent inhibition (LI) procedure was used to measure the extent of forgetting for a pre-exposed flavor over short and long retention intervals. The results indicate that rats forgot the specific characteristics of the flavor stimulus (CS) while retaining memory for pre-exposure sessions over a long retention interval. That is, subjects pre-exposed and conditioned with different concentrations of sucrose showed no LI effect with a 1-day delay between pre-exposure and training, but demonstrated a generalized LI with an 8-day delay between pre-exposure and conditioning. This experiment provides further evidence for the robustness of the forgetting of stimulus attributes, and demonstrates that this specific type of forgetting also occurs prior to the learning of a CTA task.
Dinsmoor, James A.; Mulvaney, Dallas E.; Jwaideh, Alice R.
Pigeons were provided with three keys. Pecking the center key produced grain on a schedule that alternated at unpredictable times between a variable-interval component and extinction. On concurrent variable-interval schedules, pecking either side key produced a stimulus associated with the variable-interval component on the center key provided that said schedule was currently in effect. The independent variable was the length of time this stimulus remained on the keys. Pecking one side key produced the stimulus for 27 seconds, whereas the duration produced by pecking the other key varied for successive blocks of sessions. For the first four birds, the values tested were 3, 9, 27, and 81 seconds. For the second group, numbering three birds, the values tested were 1, 3, 9, and 27 seconds. The dependent variable was the proportion of total side key pecks that occurred on the variable key. For all birds, the function was positive in slope and negative in acceleration. This finding supports a formulation that ascribes the maintenance of observing responses in a normal setting to the fact that the subject exposes itself to the positive discriminative stimulus for a longer mean duration than it does to the negative stimulus. PMID:16812230
Brandon, Susan E.; Vogel, Edgar H.; Wagner, Allan R.
THE SOP MODEL [INFORMATION PROCESSING IN ANIMALS: Memory Mechanisms, Erlbaum, Hillsdale, NJ, 1981, p. 5] is described in terms of its assumed stimulus representation, network characteristics, and rules for learning and performance. It is shown how several Pavlovian conditioning phenomena can be accounted on the basis of the model's presumed stimulus representation. Challenges to the SOP model prompted the adoption of a componential stimulus representation in: AESOP [Contemporary Learning Theories: Pavlovian Conditioning and the Status of Traditional Learning Theory, Erlbaum, Hillsdale, NJ, 1989, p. 149], this was a dual representation of the unconditioned stimulus (US), and C-SOP [Contemporary Learning: Theory and Application, Erlbaum, Mahwah, NJ, 2001, p. 23], this was a multi-component representation of the conditioned stimulus (CS). The assumption of a componential CS representation, where large numbers of elements can be separately learned about, necessitated a modification of the learning rule. The modified, "constrained" rule was found useful to explain timing characteristics of Pavlovian conditioned responses, as well as data offered by Rescorla [J. Exp. Psychol. Anim. Behav. Process. 26 (2000) 428; Q. J. Exp. Psychol. 54B (2001) 53; J. Exp. Psychol. Anim. Behav. Process. 28 (2002) 163] showing that stimuli trained in compound do not share the same quantitative fate.
Konrad-Martin, Dawn; Keefe, Douglas H.
Time-frequency representations (TFRs) of otoacoustic emissions (OAEs) provide information simultaneously in time and frequency that may be obscured in waveform or spectral analyses. TFRs were applied to transient-evoked stimulus-frequency (SF) and distortion-product (DP) OAEs to test cochlear model predictions. SFOAEs and DPOAEs were elicited in 18 normal-hearing subjects using gated tones and tone pips. Synchronous spontaneous (SS) OAEs were measured to assess their contributions to SFOAEs and DPOAEs. A common form of TFR of measured OAEs was a collection of frequency-specific components often aligned with SSOAE sites, with each component characterized by one or more brief segments or a single long-duration segment. The spectral envelope of evoked OAEs differed from that of the evoking stimulus. Strong emission regions or cochlear ``hot spots'' were detected, and sometimes accounted for OAE energy observed outside the stimulus bandwidth. Contributions of hot spots and multiple internal reflections to the OAE, and differences between measured and predicted OAE spectra, increased as stimulus level decreased, consistent with level-dependent changes in the estimated cochlear reflectance. Suppression and frequency-pulling effects between components were observed. A recursive formulation was described for the linear coherent reflection emission theory [Zweig and Shera, J. Acoust. Soc. Am. 98, 2018-2047 (1995)] that is well suited for time-domain calculations.
Robinson, Christopher W.; Sloutsky, Vladimir M.
Two experiments examined the effects of multimodal presentation and stimulus familiarity on auditory and visual processing. In Experiment 1, 10-month-olds were habituated to either an auditory stimulus, a visual stimulus, or an auditory-visual multimodal stimulus. Processing time was assessed during the habituation phase, and discrimination of…
McFarland, James M.; Bondy, Adrian G.; Saunders, Richard C.; Cumming, Bruce G.; Butts, Daniel A.
Saccadic eye movements play a central role in primate vision. Yet, relatively little is known about their effects on the neural processing of visual inputs. Here we examine this question in primary visual cortex (V1) using receptive-field-based models, combined with an experimental design that leaves the retinal stimulus unaffected by saccades. This approach allows us to analyse V1 stimulus processing during saccades with unprecedented detail, revealing robust perisaccadic modulation. In particular, saccades produce biphasic firing rate changes that are composed of divisive gain suppression followed by an additive rate increase. Microsaccades produce similar, though smaller, modulations. We furthermore demonstrate that this modulation is likely inherited from the LGN, and is driven largely by extra-retinal signals. These results establish a foundation for integrating saccades into existing models of visual cortical stimulus processing, and highlight the importance of studying visual neuron function in the context of eye movements. PMID:26370359
BLUMENFELD, HENRIKE K.; MARIAN, VIORICA
Bilinguals have been shown to outperform monolinguals at suppressing task-irrelevant information and on overall speed during cognitive control tasks. Here, monolinguals’ and bilinguals’ performance was compared on two nonlinguistic tasks: a Stroop task (with perceptual Stimulus–Stimulus conflict among stimulus features) and a Simon task (with Stimulus–Response conflict). Across two experiments testing bilinguals with different language profiles, bilinguals showed more efficient Stroop than Simon performance, relative to monolinguals, who showed fewer differences across the two tasks. Findings suggest that bilingualism may engage Stroop-type cognitive control mechanisms more than Simon-type mechanisms, likely due to increased Stimulus–Stimulus conflict during bilingual language processing. Findings are discussed in light of previous research on bilingual Stroop and Simon performance. PMID:25093009
Gouboth, Djimir; Wilder, David A; Booher, John
The effects of signaling the return of items or attention during treatment with noncontingent reinforcement were examined. First, functional analyses showed that the problem behavior exhibited by 2 teenagers with developmental disabilities was sensitive to social positive reinforcement. Next, delivery of the stimulus that maintained problem behavior on a fixed-time (FT) schedule was compared to a condition in which the removal of the stimulus during the same FT schedule was immediately preceded by a statement indicating that the stimulus would be returned and the initiation of a digital timer. Results show that the FT schedule reduced problem behavior, and the addition of an informative statement and a timer further decreased problem behavior.
Slucki, Henry; Adam, Gyorgi; Porter, Robert W.
Five rhesus macaques monkeys surgically prepared with Thiry small intestinal (jejunum) loops and implanted brain electrodes were restrained in primate chairs and kept on 23-hr deprivation-feeding cycle. After being trained to press a lever for sugar pills on an FR 25 schedule of reinforcement, a discrimination training procedure was established. Lever presses were reinforced during the SD—a non-aversive mechanical stimulus applied to the internal walls of the Thiry loop by rhythmic inflation-deflation of a small latex balloon by air at the rate of one cycle per sec at 100 mm Hg pressure. The SΔ was the absence of the visceral stimulation. The monkeys successfully discriminated between presence and absence of the internal stimulus. A discrimination reversal was attempted and completed on one monkey. The results clearly show operant discrimination based on an interoceptive stimulus. Cortical and subcortical EEG records reflected the onset but not termination of the visceral stimulation. PMID:4954822
Shinozuka, Kazutaka; Ono, Haruka; Watanabe, Shigeru
This paper investigated whether music has reinforcing and discriminative stimulus properties in goldfish. Experiment 1 examined the discriminative stimulus properties of music. The subjects were successfully trained to discriminate between two pieces of music--Toccata and Fugue in D minor (BWV 565) by J. S. Bach and The Rite of Spring by I. Stravinsky. Experiment 2 examined the reinforcing properties of sounds, including BWV 565 and The Rite of Spring. We developed an apparatus for measuring spontaneous sound preference in goldfish. Music or noise stimuli were presented depending on the subject's position in the aquarium, and the time spent in each area was measured. The results indicated that the goldfish did not show consistent preferences for music, although they showed significant avoidance of noise stimuli. These results suggest that music has discriminative but not reinforcing stimulus properties in goldfish.
Kirby, Kimberly C.; Bickel, Warren K.
Producing generality of treatment effects to new settings has been a critical concern for applied behavior analysts, but a systematic and reliable means of producing generality has yet to be provided. We argue that the principles of stimulus control and reinforcement underlie the production of most generalized effects; therefore, we suggest interpreting generalization programming in terms of stimulus control. The generalization programming procedures identified by Stokes and Baer (1977) are discussed in terms of both the stimulus control tactics explicitly identified and those that may be operating but are not explicitly identified. Our interpretation clarifies the critical components of Stokes and Baer's procedures and places greater emphasis on planning for generalization as a part of training procedures. PMID:22478006
It has been shown previously that induced aniseikonia amplifies any latent fixation eccentricity associated with binocular fusion stress. This study determines if the retinal location of the stimulus plays a part in this effect. The stimulus consisted of a vertical border formed by the juxtaposition of two fields of unequal luminances and a line segment parallel to the border whose distance from the border can be varied. At the same time, the border allowed the application of a previously tested method of measuring fixation eccentricity, based on the border-enhancement response. It was found that the fixation eccentricity produced by aniseikonia is maximal for the smallest distance of the variable target from the border but unaffected by the larger distances tested. It was concluded that the retinal location of the stimulus has an important influence on the response to aniseikonia.
Constantinidis, C; Steinmetz, M A
The primate posterior parietal cortex (PPC) plays an important role in representing and recalling spatial relationships and in the ability to orient visual attention. This is evidenced by the parietal activation observed in brain imaging experiments performed during visuo- spatial tasks, and by the contralateral neglect syndrome that often accompanies parietal lesions. Individual neurons in monkey parietal cortex respond vigorously to the appearance of single, behaviorally relevant stimuli, but little is known about how they respond to more complex visual displays. The current experiments addressed this issue by recording activity from single neurons in area 7a of the PPC in monkeys performing a spatial version of a match-to-sample task. The task required them to locate salient stimuli in multiple-stimulus displays and release a lever after a subsequent stimulus appeared at the same location. Neurons responded preferentially to the appearance of salient stimuli inside their receptive fields. The presence of multiple stimuli did not affect appreciably the spatial tuning of responses in the majority of neurons or the population code for the location of the salient stimulus. Responses to salient stimuli could be distinguished from background stimuli approximately 100 ms after the onset of the cue. These results suggest that area 7a neurons represent the location of the stimulus attracting the animal's attention and can provide the spatial information required for directing attention to a salient stimulus in a complex scene.
Carbonaro, Theresa M.; Forster, Michael J.; Gatch, Michael B.
Rationale Serotonergic hallucinogens such as (+)-lysergic acid diethylamide (LSD) and dimethyltryptamine (DMT) produce distinctive visual effects, whereas the synthetic hallucinogen N,N-diisopropyltryptamine (DiPT) is known for its production of auditory distortions. Objective: This study compares the discriminative stimulus effects of DiPT to those of visual hallucinogens. Methods Adult male rats were trained to discriminate DiPT (5 mg/kg, 15 min) from saline under a FR10 schedule. A dose-effect and time course of DiPT’s discriminative stimulus effects were established. DMT, (−)-2,5-dimethoxy-4-methylamphetamine (DOM), LSD, (±)-methylenedioxymethamphetamine (MDMA) and (+)-methamphetamine were tested for cross-substitution in DiPT-trained animals. Results Rats learned to discriminate DiPT from saline in an average of 60 training sessions (30 drug and 30 saline). DiPT (0.5 – 5 mg/kg) produced dose-dependent increases in drug-appropriate responding (DAR) to 99% (ED50 = 2.47 mg/kg). Onset of the discriminative stimulus effects was within 5 minutes and the effects dissipated within 4 hours. Full substitution for the discriminative stimulus effects of DiPT occurred with LSD, DOM and MDMA. DMT only partially substituted for DiPT (65% DAR), whereas (+)-methamphetamine failed to substitute for DiPT (29% DAR). Conclusions The discriminative stimulus effects of DiPT were similar those of a number of synthetic hallucinogens, only partially similar to those of DMT, but not similar to (+)-methamphetamine. The putative DiPT-induced auditory distortions do not lead to discriminative stimulus effects distinguishable from other hallucinogens. PMID:23070023
Herbert, Wendy J; Davidson, Adam G; Buford, John A
The pontomedullary reticular formation (PMRF) of the monkey produces motor outputs to both upper limbs. EMG effects evoked from stimulus-triggered averaging (StimulusTA) were compared with effects from stimulus trains to determine whether both stimulation methods produced comparable results. Flexor and extensor muscles of scapulothoracic, shoulder, elbow, and wrist joints were studied bilaterally in two male M. fascicularis monkeys trained to perform a bilateral reaching task. The frequency of facilitation versus suppression responses evoked in the muscles was compared between methods. Stimulus trains were more efficient (94% of PMRF sites) in producing responses than StimulusTA (55%), and stimulus trains evoked responses from more muscles per site than from StimulusTA. Facilitation (72%) was more common from stimulus trains than StimulusTA (39%). In the overall results, a bilateral reciprocal activation pattern of ipsilateral flexor and contralateral extensor facilitation was evident for StimulusTA and stimulus trains. When the comparison was restricted to cases where both methods produced a response in a given muscle from the same site, agreement was very high, at 80%. For the remaining 20%, discrepancies were accounted for mainly by facilitation from stimulus trains when StimulusTA produced suppression, which was in agreement with the under-representation of suppression in the stimulus train data as a whole. To the extent that the stimulus train method may favor transmission through polysynaptic pathways, these results suggest that polysynaptic pathways from the PMRF more often produce facilitation in muscles that would typically demonstrate suppression with StimulusTA.
Olsen, S; Osterhammel, P A; Rasmussen, A N; Nielsen, L H
Pure-tone Reference Equivalent Threshold Sound Pressure Level (RETSPL) of the ipsilateral stimulus receiver for acoustic reflex measurements on Madsen Electronics type Zodiac 901 impedance audiometer is provided. The results, obtained from 20 normal-hearing subjects, are achieved by comparing hearing threshold levels measured using a TDH 39 telephone (calibrated to ISO 389) with thresholds recorded using the ipsilateral stimulus insert phone. The calibration is referenced to an IEC-711 ear simulator and comprises the following frequencies: 125, 250, 500, 750, 1000, 1500, 2000, 3000, 4000, 6000, 8000 Hz.
Tartaglione, A; Pizio, N; Bino, G; Spadavecchia, L; Favale, E
Two stimulus configurations (gratings and checkerboards) have been presented to a series of consecutive patients with the aim of exploring VEP changes in Parkinson's disease. The outcome turned out to be quite different according to the stimulus employed. Specifically, grating pattern produced a high diagnostic yield as opposite to checkerboard, which did not reveal substantial modifications of the latency of the VEP major positive peak with respect to a control group. This finding raises problems as to the characteristics of visual changes associated with Parkinson's disease. PMID:6707679
Ono, Hiroshi; Chornenkyy, Yevgen; D'Amour, Sarah
Simulation of a given stimulus situation should produce the same perception as the original. Rogers et al (2009 Perception 38 907-911) simulated Wheeler's (1982, PhD thesis, Rutgers University, NJ) motion parallax stimulus and obtained quite different perceptions. Wheeler's observers were unable to reliably report the correct direction of depth, whereas Rogers's were. With three experiments we explored the possible reasons for the discrepancy. Our results suggest that Rogers was able to see depth from the simulation partly due to his experience seeing depth with random dot surfaces.
Bain, Anthony R; Jay, Ollie
Many thermal physiologists follow the conventional wisdom that physiological heat adaptations occur in the summer for people living in a humid continental climate (e.g. Central Canada, North-eastern and Mid-western United States and Eastern Europe); therefore experimentation across seasons is often avoided. However, since modern behavioral adaptations, such as air conditioning, are accessible and commonplace, it is not clear whether such physiological adjustments actually do occur. It was hypothesized that despite warm weather, residing in a humid continental climate throughout a summer will not elicit any significant physiological heat adaptations since the environmental stimulus for such adjustments will be mitigated by behavioral adaptations. Eight young healthy male volunteers cycled at 60% VO(2max) for 90-min in a temperate environment before (mid-May) and at the end of (start of September) summer. Core temperature [measured in the esophagus (T (es)), rectum (T (re)) and aural canal (T (au))], mean skin temperature (T (sk)), forearm skin blood flow (SkBf), upper back sweat rate (LSR) and heart rate (HR) were measured throughout exercise. Weekly activity logs and a lifestyle questionnaire were also administered throughout the summer months. No significant differences between pre- and end-summer were observed throughout exercise for T (es) (p = 0.565), T (re) (p = 0.350), T (au) (p = 0.261), T (sk) (p = 0.955), SkBf (p = 0.112), LSR (p = 0.394) or HR (p = 0.343). Likewise, the thermosensitivity and T (es) at the onset threshold for LSR (p = 0.177, p = 0.512) and SkBf (p = 0.805, p = 0.556) were also not significantly different. The apparent lack of heat acclimatization could be due to frequent air-conditioning use and an avoidance of outdoor activity during the hottest times of day but may also be due to a lack of environmental stimulus.
Barbour, Dennis L.; Wang, Xiaoqin
Contrary to findings in subcortical auditory nuclei, auditory cortex neurons have traditionally been described as spiking only at the onsets of simple sounds such as pure tones or bandpass noise and to acoustic transients in complex sounds. Furthermore, primary auditory cortex (A1) has traditionally been described as mostly tone responsive and the lateral belt area of primates as mostly noise responsive. The present study was designed to unify the study of these two cortical areas using random spectrum stimuli (RSS), a new class of parametric, wideband, stationary acoustic stimuli. We found that 60% of all neurons encountered in A1 and the lateral belt of awake marmoset monkeys (Callithrix jacchus) showed significant changes in firing rates in response to RSS. Of these, 89% showed sustained spiking in response to one or more individual RSS, a substantially greater percentage than would be expected from traditional studies, indicating that RSS are well suited for studying these two cortical areas. When firing rates elicited by RSS were used to construct linear estimates of frequency tuning for these sustained responders, the shape of the estimate function remained relatively constant throughout the stimulus interval and across the stimulus properties of mean sound level, spectral density, and spectral contrast. This finding indicates that frequency tuning computed from RSS reflects a robust estimate of the actual tuning of a neuron. Use of this estimate to predict rate responses to other RSS, however, yielded poor results, implying that auditory cortex neurons integrate information across frequency nonlinearly. No systematic difference in prediction quality between A1 and the lateral belt could be detected. PMID:12904480
Rose, H J; Metherate, R
Stimulation of the medial geniculate body in an auditory thalamocortical slice elicits a short-latency current sink in the middle cortical layers, as would be expected following activation of thalamocortical relay neurons. However, corticothalamic neurons can have axon collaterals that project to the middle layers, thus, a middle-layer current sink could also result from antidromic activation of corticothalamic neurons and their axon collaterals. The likelihood of thalamic stimulation activating corticothalamic neurons would be reduced substantially if the corticothalamic pathway was not well preserved in the slice, and/or if the threshold for antidromic activation was significantly higher than for orthodromic activation. To determine the prevalence and threshold of antidromic activation, we recorded intracellularly from day 14-17 mouse brain slices containing infragranular cortical neurons while stimulating the medial geniculate or thalamocortical pathway. Antidromic spikes were confirmed by spike collision and characterized according to spike latency "jitter" and the ability to follow a high-frequency (100 Hz) stimulus train. The ability to follow a 100-Hz tetanus was a reliable indicator of antidromic activation, but both antidromic and orthodromic spikes could have low jitter. Thalamic stimulation produced antidromic activation in two of 69 infragranular cortical neurons (<3%), indicating the presence of antidromic activity, but implying a limited corticothalamic connection in the slice. Antidromic spikes in 13 additional neurons were obtained by stimulating axons in the thalamocortical pathway. The antidromic threshold averaged 214+/-40.6 microA (range 6-475 microA), over seven times the orthodromic threshold for medial geniculate-evoked responses in layer IV extracellular (28+/-5.4 microA) or intracellular (27+/-5.6 microA) recordings. We conclude that medial geniculate stimulation activates relatively few corticothalamic neurons. Conversely, low
Alcaraz-Iborra, Manuel; Cubero, Inmaculada
Orexins (OX) are neuropeptides synthesized in the lateral hypothalamic region which play a fundamental role in a wide range of physiological and psychological functions including arousal, stress, motivation or eating behaviors. This paper reviews under the addiction cycle framework (Koob, 2010), the role of the OX system as a key modulator in compulsivity-driven consumption of rewarding stimulus including ethanol, palatable food and drugs and their role in impulsivity and binge-like consumption in non dependent organisms as well. We propose here that drug/food binge-like consumption in vulnerable organisms increases OX activity which, in turn, elicits enhanced impulsivity and further impulsivity-driven binge consumption in a positive loop that would promote compulsive-driven binge-consumption and the transition to drug/food disorders over time.
Creighton, Genevieve M; Brussoni, Mariana; Oliffe, John L; Han, Christina
This article explores the use of photo-elicitation methods in two men's health studies. Discussed are the ways that photo-elicitation can facilitate conversation about health issues that might be otherwise challenging to access. In the first study, researchers explored 35 young men's experiences of grief following the accidental death of a male peer. In the second study, researchers describe 64 fathers' perceptions about their roles and identity with respect to child safety and risk. Photographs and accompanying narratives were analyzed and results were theorized using a masculinities framework. Discussed are the benefits of photo-elicitation, which include facilitating conversation about emotions, garnering insight into the structures and identities of masculinity in the context of men's health. Considered also are some methodological challenges amid recommendations for ensuring reflexive practices. Based on the findings it is concluded that photo-elicitation can innovatively advance qualitative research in men's health.
Engel, David W.; Dalton, Angela C.
The Carbon Capture Simulation Initiative (CCSI) is a multi-laboratory simulation-driven effort to develop carbon capture technologies with the goal of accelerating commercialization and adoption in the near future. One of the key CCSI technical challenges is representing and quantifying the inherent uncertainty and risks associated with developing, testing, and deploying the technology in simulated and real operational settings. To address this challenge, the CCSI Element 7 team developed a holistic risk analysis and decision-making framework. The purpose of this report is to document the CCSI Element 7 structured systematic expert elicitation to identify additional risk factors. We review the significance of and established approaches to expert elicitation, describe the CCSI risk elicitation plan and implementation strategies, and conclude by discussing the next steps and highlighting the contribution of risk elicitation toward the achievement of the overarching CCSI objectives.
Muthukumaraswamy, S D; Singh, K D
Increases in the power of neural oscillations in the gamma (>40 Hz) band are a key signature of information processing in cortical neuronal networks. However, non-invasive detection of these very small oscillations is difficult due to the presence of potential artefacts (both muscular and ocular) in the same frequency band and requires highly optimised paradigms. Numerous studies have shown that the properties of visual gamma-band responses to simple pattern stimuli are highly tuned to the stimuli parameters used. The aim of this work was to compare gamma oscillation response properties across some of the more commonly used stimulus configurations. To do this, MEG and EEG recordings were made during the presentation of eight different stimulus types in a 2 × 2 × 2 design. For the first stimulus factor, "Type", the stimulus pattern was either an annulus grating or a square wave grating. For the second stimulus factor, "Field", stimuli were presented in either four visual field quadrants simultaneously or only in the lower left quadrant. Finally, for the "Move" factor, stimuli either drifted at 1.33°s(-1) or were stationary. For MEG gamma band responses, the following main effects were observed, a) gamma-band power was increased for annular stimuli compared to square wave stimuli, b) gamma-band power was increased for full field stimuli compared to single quadrant stimuli and c) gamma-band power was larger for drifting compared to stationary stimuli and were of significantly higher frequency. For the detectors used, the signal to noise ratio was substantially higher for MEG than EEG. The advantages and disadvantages of the different types of stimulus types are discussed.
Shou, Guofa; Dasari, Deepika; Ding, Lei
Performance errors have been attributed to distinct neural mechanisms in different tasks. Two temporally and physiologically dissociable neural patterns prior to errors, i.e., pre-stimulus alpha (8-13 Hz) power indicative of sustained attention and post-stimulus N2 amplitude indicative of cognitive control, have been widely (but independently) reported in many studies. However, it is still largely unknown whether these two neural mechanisms for error commission exist in a single task at the same time and, if so, whether they can be probed simultaneously and how they lead to response accuracy (collectively or separately). To this end, we measured high-density electroencephalography (EEG) signals in a color-word matching Stroop task. We quantified both patterns on EEG data from individual stimulus condition (congruent or incongruent), as well as on pooled data from both conditions. Enhanced pre-stimulus alpha power for errors was identified over the parieto-occipital area in the congruent condition and the pooled data. Reduced post-stimulus N2 amplitude was only revealed in the incongruent condition. More importantly, for the first time, a balanced interaction between these two EEG patterns was revealed in correct trials, but not in error trials. These findings suggest that errors in one task could occur due to distinct neural mechanisms, e.g., poor sustained attention, poor cognitive control, or missed balance between these two. The present results further suggest that the detection of neural patterns related to different neural mechanisms could be complicated by other modulation factors, such as stimulus condition. Therefore, more than one neural marker should be simultaneously monitored to effectively predict imminent errors.
Mouraux, André; Marot, Emilie; Legrain, Valéry
Currently, the study of nociception in humans relies mainly on thermal stimulation of heat-sensitive nociceptive afferents. To circumvent some limitations of thermal stimulation, it was proposed that intra-epidermal electrical stimulation (IES) could be used as an alternative method to activate nociceptors selectively. The selectivity of IES relies on the fact that it can generate a very focal electrical current and, thereby, activate nociceptive free nerve endings located in the epidermis without concomitantly activating non-nociceptive mechanoreceptors located more deeply in the dermis. However, an important limitation of IES is that it is selective for nociceptors only when very low current intensities are used. At these intensities, the stimulus generates a very weak percept, and the signal-to-noise ratio of the elicited evoked potentials (EPs) is very low. To circumvent this limitation, it was proposed that the strength of the nociceptive afferent volley could be increased through temporal summation, using short trains of repeated IES. Here, we characterized the intensity of perception and EPs elicited by trains of 2, 3 and 4 IES delivered using a 5-ms inter-stimulus interval. We found that both the intensity of perception and the magnitude of EPs significantly increased with the number of pulses. In contrast, the latency of the elicited EPs was not affected by the number of pulses, indicating that temporal summation did not affect the type of activated fibers and, therefore, that trains of IES can be used to increase the reliability of stimulus-evoked responses while still preserving its selectivity for nociceptors.
where reasonable, to counteract known biases in elicitation). 1 For the triangle distribution, the probability is set to zero outside the endpoints...probability is set to zero outside the endpoints, while between the endpoints the density rises linearly from the lower value to the most-likely values...Wheeler, T. A., S. C. Hora , W. R. Cramond, and S. D. Unwin, Analysis of Core Damage Frequency from Internal Events: Expert Judgment Elicitation
artificial intelligence has been focused on methods for eliciting and representing expert knowledge (e.g., Newell and Simon, 1972; Schank and Abelson...methods. These issues have not yet been dealt with in a satisfactory way, either in the artificial intelligence community or by cognitive psychologists...ELICITATION 2.1 The Myth of "Mining for Nugets" of Knowledge The central question in the field of artificial intelligence, whether computers can be
Kaltwasser, C; Horn, F K; Kremers, J; Juenemann, A; Bergua, A
We present the case of a 59-year-old male patient with progressive vision impairment and consecutive visual field narrowing ("tunnel view") for 7 years and a known retinitis pigmentosa for 5 years. The remaining Goldmann perimetric visual field at time reported was less than 5°. A request for blindness-related social benefits was rejected because an ophthalmologic expert assessment suggested malingering. This prompted us to assess an objective determination of the visual field using multifocal VEPs. Objective visual field recordings were performed with a four-channel multifocal VEP-perimeter using 58 stimulus fields (pattern reversal dartboard stimulus configuration). The correlated signal data were processed using an off-line method. At each field, the recording from the channel with the maximal signal-to-noise ratio (SNR) was retained, thus resulting in an SNR optimized virtual recording. Analysis of VEP signals was performed for each single field and concentric rings and compared to an average response measured in five healthy subjects. Substantial VEP responses could be identified in three fields within the innermost ring (eccentricity, 1.7°) for both eyes, although SNR was generally low. More eccentric stimuli did not elicit reliable VEP responses. The mfVEP recording was correlated with perimetric visual field data. The current SNR optimization by using the channel with the largest SNR provides a good method to extract useful data from recordings and may be appropriate for the use in forensic ophthalmology.
Wang, Yu-Te; Wang, Yijun; Cheng, Chung-Kuan; Jung, Tzyy-Ping
This study integrates visual stimulus presentation and near real-time data processing on a mobile device (e.g. a Tablet or a cell-phone) to implement a steady-state visual evoked potentials (SSVEP)-based brain-computer interface (BCI). The goal of this study is to increase the practicability, portability and ubiquity of an SSVEP-based BCI for daily use. The accuracy of flickering frequencies on the mobile SSVEP BCI system was tested against that on a laptop/desktop used in our previous studies. This study then analyzed the power spectrum density of the electroencephalogram signals elicited by the visual stimuli rendered on the mobile BCIs. Finally, this study performed an online test with the Tablet-based BCI system and obtained an averaged information transfer rate of 33.87 bits/min in three subjects. The current integration leads to a truly practical and ubiquitous SSVEP BCI on mobile devices for real-life applications.
Koch, Jennifer; Flemming, Jan; Zeffiro, Thomas; Rufer, Michael; Orr, Scott P; Mueller-Pfeiffer, Christoph
In the "loud-tone" procedure, a series of brief, loud, pure-tone stimuli are presented in a task-free situation. It is an established paradigm for measuring autonomic sensitization in posttraumatic stress disorder (PTSD). Successful use of this procedure during fMRI requires elicitation of brain responses that have sufficient signal-noise ratios when recorded in a supine, rather than sitting, position. We investigated the modulating effects of posture and stimulus spectral composition on peripheral psychophysiological responses to loud sounds. Healthy subjects (N = 24) weekly engaged in a loud-tone-like procedure that presented 500 msec, 95 dB sound pressure level, pure-tone or white-noise stimuli, either while sitting or supine and while peripheral physiological responses were recorded. Heart rate, skin conductance, and eye blink electromyographic responses were larger to white-noise than pure-tone stimuli (p's < 0.001, generalized eta squared 0.073-0.076). Psychophysiological responses to the stimuli were similar in the sitting and supine position (p's ≥ 0.082). Presenting white noise, rather than pure-tone, stimuli may improve the detection sensitivity of the neural concomitants of heightened autonomic responses by generating larger responses. Recording in the supine position appears to have little or no impact on psychophysiological response magnitudes to the auditory stimuli.
Koivisto, Mika; Grassini, Simone
Does visual awareness correlate with early activity in visual cortex or with later wide-spread neural activation? This question was studied by presenting liminal targets in one of the four quadrants of the screen and asking the participants to make forced-choice localization responses and to rate their subjective visual awareness of each target, while electroencephalography was measured. In the analyses of event-related potential (ERP) correlates of awareness, response accuracy was kept constant so that only the subjectively rated awareness varied between high-awareness ('seen' rating) and low-awareness ('unseen' rating) targets. High-awareness-correct trials were associated with enhanced contralateral N200 at 180-280 ms as compared with low-awareness-correct trials. This effect (visual awareness negativity, VAN) also correlated with aware sensitivity to the presence vs. absence of the stimulus (d'). In addition, high-awareness-correct trials were associated with later enhanced P3 amplitudes (after 350 ms), but this effect correlated only with the response bias (c). ERPs to low-awareness-correct trials elicited larger contralateral N200 than ERPs to low-awareness-incorrect trials, and this effect correlated with conservative response bias, suggesting that it reflected weak awareness rather than unconscious processing. The results suggest that the enhanced N200 correlates with graded awareness. The results support theories of visual awareness in which early activity in visual cortex gives rise to subjective visual experiences.
Koch, Jennifer; Flemming, Jan; Zeffiro, Thomas; Rufer, Michael; Orr, Scott P.; Mueller-Pfeiffer, Christoph
In the “loud-tone” procedure, a series of brief, loud, pure-tone stimuli are presented in a task-free situation. It is an established paradigm for measuring autonomic sensitization in posttraumatic stress disorder (PTSD). Successful use of this procedure during fMRI requires elicitation of brain responses that have sufficient signal-noise ratios when recorded in a supine, rather than sitting, position. We investigated the modulating effects of posture and stimulus spectral composition on peripheral psychophysiological responses to loud sounds. Healthy subjects (N = 24) weekly engaged in a loud-tone-like procedure that presented 500 msec, 95 dB sound pressure level, pure-tone or white-noise stimuli, either while sitting or supine and while peripheral physiological responses were recorded. Heart rate, skin conductance, and eye blink electromyographic responses were larger to white-noise than pure-tone stimuli (p’s < 0.001, generalized eta squared 0.073–0.076). Psychophysiological responses to the stimuli were similar in the sitting and supine position (p’s ≥ 0.082). Presenting white noise, rather than pure-tone, stimuli may improve the detection sensitivity of the neural concomitants of heightened autonomic responses by generating larger responses. Recording in the supine position appears to have little or no impact on psychophysiological response magnitudes to the auditory stimuli. PMID:27583659
Nieto-Diego, Javier; Malmierca, Manuel S
Stimulus-specific adaptation (SSA) in single neurons of the auditory cortex was suggested to be a potential neural correlate of the mismatch negativity (MMN), a widely studied component of the auditory event-related potentials (ERP) that is elicited by changes in the auditory environment. However, several aspects on this SSA/MMN relation remain unresolved. SSA occurs in the primary auditory cortex (A1), but detailed studies on SSA beyond A1 are lacking. To study the topographic organization of SSA, we mapped the whole rat auditory cortex with multiunit activity recordings, using an oddball paradigm. We demonstrate that SSA occurs outside A1 and differs between primary and nonprimary cortical fields. In particular, SSA is much stronger and develops faster in the nonprimary than in the primary fields, paralleling the organization of subcortical SSA. Importantly, strong SSA is present in the nonprimary auditory cortex within the latency range of the MMN in the rat and correlates with an MMN-like difference wave in the simultaneously recorded local field potentials (LFP). We present new and strong evidence linking SSA at the cellular level to the MMN, a central tool in cognitive and clinical neuroscience.
Ward, Daniel; Morison, Françoise; Morrissey, Elizabeth; Jenks, Kyle; Watson, Winsor H
American lobsters (Homarus americanus) will on rare occasions produce sounds by vibrating their dorsal carapace. Although this behavior can be elicited in the laboratory by handling lobsters, the stimulus that triggers the production of sounds in the lobster's natural habitat is not known. We investigated the influence of two fish that are known to prey on lobsters, cod (Gadus morhua) and striped bass (Morone saxatilis), on the production of sounds by American lobsters. In addition, we examined the response of the same fish to the sounds the lobsters produced. Although solitary lobsters spontaneously produced sounds at a low rate of 1.2 ± 0.23 sound events per 30 min, the presence of a single cod or striped bass led to an increase in the rate of sound production (cod: 51.1 ± 13.1 events per 30 min; striped bass: 17.0 ± 7.0 events per 30 min). Most (74.6 ± 6.6%) of the 292 sound events recorded occurred when a fish came within 0.5 m of a lobster, but a fish did not have to come into contact with a lobster to elicit sounds. Immediately following the production of a sound by a lobster, fish turned and swam away significantly faster than when they encountered a lobster that did not make a sound. Moreover, after striped bass (but not cod) experienced a number of these sound events, they subsequently tended to avoid swimming close to the lobsters. These data, taken together, suggest that sound production by American lobsters may serve to deter potential fish predators.
Callejas, Alicia; Acosta, Alberto; Lupiáñez, Juan
Synesthetes who experience grapheme-color synesthesia often report feeling uneasy when dealing with incongruently colored graphemes although no empirical data is available to confirm this phenomenon. We studied this affective reaction related to synesthetic perceptions by means of an evaluation task. We found that the perception of an incorrectly colored word affects the judgments of emotional valence. Furthermore, this effect competed with the word's emotional valence in a categorization task thus supporting the automatic nature of this synesthetically elicited affective reaction. When manipulating word valence and word color-photism congruence, we found that responses were slower (and less accurate) for inconsistent conditions than for consistent conditions. Inconsistent conditions were defined as those where semantics and color-photism congruence did not produce a similar assessment and therefore gave rise to a negative affective reaction (i.e., positive-valence words presented in a color different from the synesthete's photism or negative-valence words presented in the photism's color). We therefore observed a modulation of the congruency effect (i.e., faster reaction times to congruently colored words than incongruently colored words). Although this congruence effect has been taken as an index of the true experience of synesthesia, we observed that it can be reversed when the experimental manipulations turn an incongruently colored word into a consistent stimulus. To our knowledge, this is the first report of an affective reaction elicited by the congruency between the synesthetically induced color of a word and the color in which the word is actually presented. The underlying neural mechanisms that might be involved in this phenomenon are discussed.
Help for colleges may be on the way in the $825-billion stimulus package being pressed by Congressional leaders. The bill that House Democrats introduced this month includes $7-billion for higher-education modernization, renovation, and repair that could kick-start projects like upgrading heating and cooling systems, fixing roofs, and doing…
Richman, D M; Wacker, D P; Cooper-Brown, L J; Kayser, K; Crosland, K; Stephens, T J; Asmus, J
Three experiments were conducted in an outpatient setting with young children who had been referred for treatment of noncompliant behavior and who had coexisting receptive language or receptive vocabulary difficulties. Experiment 1 studied differential responding of the participants to a brief hierarchical directive analysis (least-to-most complex stimulus prompts) to identify directives that functioned as discriminative stimuli for accurate responding. Experiment 1 identified distinct patterns of accurate responding relative to manipulation of directive stimulus characteristics. Experiment 2 demonstrated that directives identified as effective or ineffective in obtaining stimulus control of accurate responding during Experiment 1 continued to control accurate responding across play activities and academic tasks. Experiment 3 probed effects of the interaction between the type of directive (effective vs. ineffective) and the reinforcement contingency (differential reinforcement for attempts vs. differential reinforcement for accurate responses) on accurate task completion and disruptive behavior. Results suggested that behavioral escalation from inaccurate responding to disruptive behavior occurred only when ineffective directives were combined with differential reinforcement for accurate task completion. The overall results are discussed in terms of developing a methodology for identifying stimulus characteristics of directives that affect accurate responding. PMID:11678525
Dube, William V.; Farber, Rachel S.; Mueller, Marlana R.; Grant, Eileen; Lorin, Lucy; Deutsch, Curtis K.
Stimulus overselectivity refers to maladaptive narrow attending that is a common learning problem among children with intellectual disabilities and frequently associated with autism. The present study contrasted overselectivity among groups of children with autism, Down syndrome, and typical development. The groups with autism and Down syndrome…
Turner, Brandon M.; Van Zandt, Trisha; Brown, Scott
Signal detection theory forms the core of many current models of cognition, including memory, choice, and categorization. However, the classic signal detection model presumes the a priori existence of fixed stimulus representations--usually Gaussian distributions--even when the observer has no experience with the task. Furthermore, the classic…
Mysore, Shreesh P.; Asadollahi, Ali; Knudsen, Eric I.
Stimulus selection for gaze and spatial attention involves competition among stimuli across sensory modalities and across all of space. We demonstrate that such cross-modal, global competition takes place in the intermediate and deep layers of the optic tectum, a structure known to be involved in gaze control and attention. A variety of either visual or auditory stimuli located anywhere outside of a neuron's receptive field (RF) were shown to suppress or completely eliminate responses to a visual stimulus located inside the RF in nitrous oxide sedated owls. The essential mechanism underlying this stimulus competition is global, divisive inhibition. Unlike the effect of the classical inhibitory surround, which decreases with distance from the RF center and shapes neuronal responses to individual stimuli, global inhibition acts across the entirety of space and modulates responses primarily in the context of multiple stimuli. Whereas the source of this global inhibition is as yet unknown, our data indicate that different networks mediate the classical surround and global inhibition. We hypothesize that this global, cross-modal inhibition, which acts automatically in a bottom-up fashion even in sedated animals, is critical to the creation of a map of stimulus salience in the optic tectum. PMID:20130182
Winter, J C; Rice, K C; Amorosi, D J; Rabin, R A
Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT(2A) receptor antagonist, M100907. In contrast, no significant antagonism was observed following treatment with the 5-HT(1A/7) receptor antagonist, WAY-100635, or the DA D(2) antagonist, remoxipride. Psilocybin generalized fully to DOM, LSD, psilocin, and, in the presence of WAY-100635, DMT while partial generalization was seen to 2C-T-7 and mescaline. LSD and MDMA partially generalized to psilocybin and these effects were completely blocked by M-100907; no generalization of PCP to psilocybin was seen. The present data suggest that psilocybin induces a compound stimulus in which activity at the 5-HT(2A) receptor plays a prominent but incomplete role. In addition, psilocybin differs from closely related hallucinogens such as 5-MeO-DMT in that agonism at 5-HT(1A) receptors appears to play no role in psilocybin-induced stimulus control.
Segev, Ronen; Schneidman, Elad
Neural populations encode information about their stimulus in a collective fashion, by joint activity patterns of spiking and silence. A full account of this mapping from stimulus to neural activity is given by the conditional probability distribution over neural codewords given the sensory input. For large populations, direct sampling of these distributions is impossible, and so we must rely on constructing appropriate models. We show here that in a population of 100 retinal ganglion cells in the salamander retina responding to temporal white-noise stimuli, dependencies between cells play an important encoding role. We introduce the stimulus-dependent maximum entropy (SDME) model—a minimal extension of the canonical linear-nonlinear model of a single neuron, to a pairwise-coupled neural population. We find that the SDME model gives a more accurate account of single cell responses and in particular significantly outperforms uncoupled models in reproducing the distributions of population codewords emitted in response to a stimulus. We show how the SDME model, in conjunction with static maximum entropy models of population vocabulary, can be used to estimate information-theoretic quantities like average surprise and information transmission in a neural population. PMID:23516339
Interference control, the ability to overcome distraction from irrelevant information, undergoes considerable improvement during childhood, yet the mechanisms driving these changes remain unclear. The present study investigated the relative influence of interference at the level of the stimulus or the response. Seven-, 10-, and 20-year-olds…
Gouboth, Djimir; Wilder, David A.; Booher, John
The effects of signaling the return of items or attention during treatment with noncontingent reinforcement were examined. First, functional analyses showed that the problem behavior exhibited by 2 teenagers with developmental disabilities was sensitive to social positive reinforcement. Next, delivery of the stimulus that maintained problem…
Redd, William H.
Generalization of stimulus control in different situations and with novel adults occurred with those children who were trained by contingent reinforcement, but not with those trained by both contingent and noncontingent reinforcement. This research was submitted as part of the author's dissertation. (MH)
Samson, Andrea C.; Hegenloh, Michael
The present paper aims to investigate whether individuals with Asperger syndrome (AS) show global humor processing deficits or whether humor comprehension and appreciation depends on stimulus characteristics. Non-verbal visual puns, semantic and Theory of Mind cartoons were rated on comprehension, funniness and the punchlines were explained. AS…
Shaw, Paul; Nikolopoulos, Thomas
Visual reinforcement audiometry (VRA) is routinely used with infants to assess hearing level. It is an operant procedure based on the association of auditory and visual stimuli. There are several recommended test procedures for VRA. One clinical VRA procedure involves presenting the initial auditory stimulus without activation of the visual reward. If the infant generates a head orientation response, the visual reward is then activated. The aim of this study was to investigate the unconditioned response rates (head orientation towards loudspeaker) to two different sound-field-presented stimuli, 1000-Hz narrowband noise (NBN) and 1000-Hz frequency-modulated tones (FMTs), using this VRA procedure. For each stimulus type, 100 infants presenting for VRA were assessed (age range 6-30 months, mean age 13 months). Of the infants presented with NBN, 69% responded, compared to 25% of infants presented with FMTs. Chi-squared analysis revealed a highly significant statistical difference in favour of NBN. In conclusion, this study demonstrated the effectiveness of using a 1000-Hz NBN stimulus over a 1000-Hz FMT stimulus in securing an unconditioned head orientation response in infants presenting for VRA.
Arduino, Lisa S; Vallar, Giuseppe; Burani, Cristina
The present study investigated the effects of the duration of the stimulus on the reading performance of right-brain-damaged patients with left neglect dyslexia. Three Italian patients read aloud words and nonwords, under conditions of unlimited time of stimulus exposure and of timed presentation. In the untimed condition, the majority of the patients' errors involved the left side of the letter string (i.e., neglect dyslexia errors). Conversely, in the timed condition, although the overall level of performance decreased, errors were more evenly distributed across the whole letter string (i.e., visual - nonlateralized - errors). This reduction of neglect errors with a reduced time of presentation of the stimulus may reflect the read out of elements of the letter string from a preserved visual storage component, such as iconic memory. Conversely, a time-unlimited presentation of the stimulus may bring about the rightward bias that characterizes the performance of neglect patients, possibly by a capture of the patients' attention by the final (rightward) letters of the string.
Runquist, Willard N.
Nelson, Brooks, and Wheeler (1975) found that interference effects produced by physical similarity among word stimuli in paired associates result from the disruption of contact with the functional stimulus and that interference with associative retrieval is minimal. Data in this research challenge their conclusion on several grounds. (Author/RK)
Watanabe, Hidehiro; Sato, Chihiro; Kuramochi, Tomokazu; Nishino, Hiroshi; Mizunami, Makoto
Classical conditioning of olfactory conditioning stimulus (CS) with gustatory unconditioned stimulus (US) in insects has been used as a pertinent model for elucidation of neural mechanisms underlying learning and memory. However, a conditioning system in which stable intracellular recordings from brain neurons are feasibly obtained while monitoring the conditioning effect has remained to be established. Recently, we found classical conditioning of salivation in cockroaches Periplaneta americana, in which an odor was associated with sucrose solution applied to the mouth, and this conditioning could be monitored by activities of salivary neurons. Application of gustatory US to the mouth, however, leads to feeding movement accompanying a movement of the brain that prevents stable recordings from brain neurons. Here we investigated whether a gustatory stimulus presented to an antenna could serve as an effective US for producing salivary conditioning. Presentation of sucrose or sodium chloride solution to an antenna induced salivation and also increased activities of salivary neurons. A single pairing trial of an odor with antennal presentation of sucrose or sodium chloride solution produced conditioning of salivation or of activities of salivary neurons. Five pairing trials led to a conditioning effect that lasted for one day. Water or tactile stimulus presented to an antenna was not effective for producing conditioning. The results demonstrate that gustatory US presented to an antenna is as effective as that presented to the mouth for producing salivary conditioning. This conditioning system provides a useful model for studying the neural basis of learning at the level of singly identifiable neurons.
Dickson, Chata A.; Wang, Sharon S.; Lombard, Kristin M.; Dube, William V.
Overselective stimulus control was assessed in 29 students at residential schools for individuals with developmental disabilities. Overselectivity testing included three different delayed identity matching-to-sample tasks. Sample stimuli for the Form/Color Test were nine possible combinations of three colors and three forms. On each trial, the S+…
Winter, J.C.; Rice, K.C.; Amorosi, D.J.; Rabin, R.A.
Although psilocybin has been trained in the rat as a discriminative stimulus, little is known of the pharmacological receptors essential for stimulus control. In the present investigation rats were trained with psilocybin and tests were then conducted employing a series of other hallucinogens and presumed antagonists. An intermediate degree of antagonism of psilocybin was observed following treatment with the 5-HT2A receptor antagonist, M100907. In contrast, no significant antagonism was observed following treatment with the 5-HT1A/7 receptor antagonist, WAY-100635, or the DA D2 antagonist, remoxipride. Psilocybin generalized fully to DOM, LSD, psilocin, and, in the presence of WAY-100635, DMT while partial generalization was seen to 2C-T-7 and mescaline. LSD and MDMA partially generalized to psilocybin and these effects were completely blocked by M-100907; no generalization of PCP to psilocybin was seen. The present data suggest that psilocybin induces a compound stimulus in which activity at the 5-HT2A receptor plays a prominent but incomplete role. In addition, psilocybin differs from closely related hallucinogens such as 5-MeO-DMT in that agonism at 5-HT1A receptors appears to play no role in psilocybin-induced stimulus control. PMID:17688928
Bailey, Alexandria R.; Chow, Jonathan J.; Beckmann, Joshua S.; Zentall, Thomas R.
Pigeons have shown suboptimal gambling-like behavior when preferring a stimulus that infrequently signals reliable reinforcement over alternatives that provide greater reinforcement overall. As a mechanism for this behavior, recent research proposed that the stimulus value of alternatives with more reliable signals for reinforcement will be preferred relatively independently of their frequencies. The present study tested this hypothesis using a simplified design of a Discriminative alternative that, 50% of the time, led to either a signal for 100% reinforcement or a blackout period indicative of 0% reinforcement against a Nondiscriminative alternative that always led to a signal that predicted 50% reinforcement. Pigeons showed a strong preference for the Discriminative alternative that remained despite reducing the frequency of the signal for reinforcement in subsequent phases to 25% and then 12.5%. In Experiment 2, using the original design of Experiment 1, the stimulus following choice of the Nondiscriminative alternative was increased to 75% and then to 100%. Results showed that preference for the Discriminative alternative decreased only when the signals for reinforcement for the two alternatives predicted the same probability of reinforcement. The ability of several models to predict this behavior are discussed, but the terminal link stimulus value offers the most parsimonious account of this suboptimal behavior. PMID:27441394
Bourdeaux, Carolyn; Warner, Nicholas
Between 2009 and 2011, school districts across the country received federal stimulus funds to shore up their budgets during the recession. The hope was that this support would serve as bridge funding during the recession, and that jurisdictions would then replace the federal funds as state and local tax bases grew stronger. However, the research…
Coelho, Cesar A. O.; Dunsmoor, Joseph E.; Phelps, Elizabeth A.
Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately…
Katz, Phyllis A.
The purposes of this study were (1) to investigate the possibility that children's racial attitudes could be modified by means of stimulus predifferentiation training, (2) to assess the developmental implications of such training, and (3) to assess the relative sensitivity of two different attitude measures to such manipulation. Subjects were 96…
Harding, Jay W.; Wacker, David P.; Berg, Wendy K.; Rick, Gary; Lee, John F.
The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack.…
The prospect of sharing in the $100 billion in federal economic-stimulus aid has companies unleashing their sales pitches. Pittsburgh-based Apangea Learning, which offers online one-on-one tutoring, is offering school districts three years' worth of services for the price of two, to "help schools win new federal funding that is part of the…
Leader, Geraldine; Loughnane, Ann; McMoreland, Claire; Reed, Phil
The influence of stimulus salience on over-selective responding was investigated in the context of a comparator theory of over-selectivity. In Experiments 1 and 2, participants were presented with two cards, each displaying two colors. In comparison to matched control participants, participants with Autistic Spectrum Disorder (ASD) demonstrated…
McDonnell, Lorraine M.; Weatherford, M. Stephen
The economic stimulus enacted during President Obama's initial weeks included a down payment on his ambitious education reform agenda. By combining short-term policy with reform, the strategy gained his administration three advantages: a discretionary funding source with little Congressional scrutiny; flexibility in pursuing education reform goals…
Freeman, Kurt A.; Piazza, Cathleen C.
The food refusal of a 6-year-old girl with autism and destructive behavior was treated using stimulus fading, reinforcement, and escape extinction. Intake increased, and compliance with prompting procedures remained relatively stable despite the increased consumption requirement. (Author/CR)
Reed, Phil; Savile, Amy; Truzoli, Roberto
Stimulus over-selectivity is a phenomenon often displayed by individuals with many forms of developmental and intellectual disabilities, and also by individuals lacking such disabilities who are under cognitive strain. It occurs when only one of potentially many aspects of the environment controls behavior. Adult participants were trained and…
Podlesnik, Christopher A; Bai, John Y H; Elliffe, Douglas
Reinforcing an alternative response in the same context as a target response reduces the rate of occurrence but increases the persistence of that target response. Applied researchers who use such techniques to decrease the rate of a target problem behavior risk inadvertently increasing the persistence of the same problem behavior. Behavioral momentum theory asserts that the increased persistence is a function of the alternative reinforcement enhancing the Pavlovian relation between the target stimulus context and reinforcement. A method showing promise for reducing the persistence-enhancing effects of alternative reinforcement is to train the alternative response in a separate stimulus context before combining with the target stimulus in extinction. The present study replicated previous findings using pigeons by showing that combining an "alternative" richer VI schedule (96 reinforcers/hr) with a "target" leaner VI schedule (24 reinforcers/hr) reduced resistance to extinction of target responding compared with concurrent training of the alternative and target responses (totaling 120 reinforcers/hr). We also found less relapse with a reinstatement procedure following extinction with separate-context training, supporting previous findings that training conditions similarly influence both resistance to extinction and relapse. Finally, combining the alternative stimulus context was less disruptive to target responding previously trained in the concurrent schedule, relative to combining with the target response trained alone. Overall, the present findings suggest the technique of combining stimulus contexts associated with alternative responses with those associated with target responses disrupts target responding. Furthermore, the effectiveness of this disruption is a function of training context of reinforcement for target responding, consistent with assertions of behavioral momentum theory.
Podlesnik, Christopher A; Bai, John Y. H; Elliffe, Douglas
Reinforcing an alternative response in the same context as a target response reduces the rate of occurrence but increases the persistence of that target response. Applied researchers who use such techniques to decrease the rate of a target problem behavior risk inadvertently increasing the persistence of the same problem behavior. Behavioral momentum theory asserts that the increased persistence is a function of the alternative reinforcement enhancing the Pavlovian relation between the target stimulus context and reinforcement. A method showing promise for reducing the persistence-enhancing effects of alternative reinforcement is to train the alternative response in a separate stimulus context before combining with the target stimulus in extinction. The present study replicated previous findings using pigeons by showing that combining an “alternative” richer VI schedule (96 reinforcers/hr) with a “target” leaner VI schedule (24 reinforcers/hr) reduced resistance to extinction of target responding compared with concurrent training of the alternative and target responses (totaling 120 reinforcers/hr). We also found less relapse with a reinstatement procedure following extinction with separate-context training, supporting previous findings that training conditions similarly influence both resistance to extinction and relapse. Finally, combining the alternative stimulus context was less disruptive to target responding previously trained in the concurrent schedule, relative to combining with the target response trained alone. Overall, the present findings suggest the technique of combining stimulus contexts associated with alternative responses with those associated with target responses disrupts target responding. Furthermore, the effectiveness of this disruption is a function of training context of reinforcement for target responding, consistent with assertions of behavioral momentum theory. PMID:23008521
Saunders, Kathryn J; Hine, Kathleen; Hayashi, Yusuke; Williams, Dean C
Persistent error patterns sometimes develop when teaching new discriminations. These patterns can be adventitiously reinforced, especially during long periods of chance-level responding (including baseline). Such behaviors can interfere with learning a new discrimination. They can also disrupt already learned discriminations, if they re-emerge during teaching procedures that generate errors. We present an example of this process. Our goal was to teach a boy with intellectual disabilities to touch one of two shapes on a computer screen (in technical terms, a simple simultaneous discrimination). We used a size-fading procedure. The correct stimulus was at full size, and the incorrect-stimulus size increased in increments of 10 %. Performance was nearly error free up to and including 60 % of full size. In a probe session with the incorrect stimulus at full size, however, accuracy plummeted. Also, a pattern of switching between choices, which apparently had been established in classroom instruction, re-emerged. The switching pattern interfered with already-learned discriminations. Despite having previously mastered a fading step with the incorrect stimulus up to 60 %, we were unable to maintain consistently high accuracy beyond 20 % of full size. We refined the teaching program such that fading was done in smaller steps (5 %), and decisions to "step back" to a smaller incorrect stimulus were made after every 5-instead of 20-trials. Errors were rare, switching behavior stopped, and he mastered the discrimination. This is a practical example of the importance of designing instruction that prevents adventitious reinforcement of maladaptive discriminated response patterns by reducing errors during acquisition.
Jalligampala, Archana; Sekhar, Sudarshan; Zrenner, Eberhart; Rathbun, Daniel L
To further improve the quality of visual percepts elicited by microelectronic retinal prosthetics, substantial efforts have been made to understand how retinal neurons respond to electrical stimulation. It is generally assumed that a sufficiently strong stimulus will recruit most retinal neurons. However, recent evidence has shown that the responses of some retinal neurons decrease with excessively strong stimuli (a non-monotonic response function). Therefore, it is necessary to identify stimuli that can be used to activate the majority of retinal neurons even when such non-monotonic cells are part of the neuronal population. Taking these non-monotonic responses into consideration, we establish the optimal voltage stimulation parameters (amplitude, duration, and polarity) for epiretinal stimulation of network-mediated (indirect) ganglion cell responses. We recorded responses from 3958 mouse retinal ganglion cells (RGCs) in both healthy (wild type, WT) and a degenerating (rd10) mouse model of retinitis pigmentosa-using flat-mounted retina on a microelectrode array. Rectangular monophasic voltage-controlled pulses were presented with varying voltage, duration, and polarity. We found that in 4-5 weeks old rd10 mice the RGC thresholds were comparable to those of WT. There was a marked response variability among mouse RGCs. To account for this variability, we interpolated the percentage of RGCs activated at each point in the voltage-polarity-duration stimulus space, thus identifying the optimal voltage-controlled pulse (-2.4 V, 0.88 ms). The identified optimal voltage pulse can activate at least 65% of potentially responsive RGCs in both mouse strains. Furthermore, this pulse is well within the range of stimuli demonstrated to be safe and effective for retinal implant patients. Such optimized stimuli and the underlying method used to identify them support a high yield of responsive RGCs and will serve as an effective guideline for future in vitro investigations of
Jalligampala, Archana; Sekhar, Sudarshan; Zrenner, Eberhart; Rathbun, Daniel L.
To further improve the quality of visual percepts elicited by microelectronic retinal prosthetics, substantial efforts have been made to understand how retinal neurons respond to electrical stimulation. It is generally assumed that a sufficiently strong stimulus will recruit most retinal neurons. However, recent evidence has shown that the responses of some retinal neurons decrease with excessively strong stimuli (a non-monotonic response function). Therefore, it is necessary to identify stimuli that can be used to activate the majority of retinal neurons even when such non-monotonic cells are part of the neuronal population. Taking these non-monotonic responses into consideration, we establish the optimal voltage stimulation parameters (amplitude, duration, and polarity) for epiretinal stimulation of network-mediated (indirect) ganglion cell responses. We recorded responses from 3958 mouse retinal ganglion cells (RGCs) in both healthy (wild type, WT) and a degenerating (rd10) mouse model of retinitis pigmentosa—using flat-mounted retina on a microelectrode array. Rectangular monophasic voltage-controlled pulses were presented with varying voltage, duration, and polarity. We found that in 4–5 weeks old rd10 mice the RGC thresholds were comparable to those of WT. There was a marked response variability among mouse RGCs. To account for this variability, we interpolated the percentage of RGCs activated at each point in the voltage-polarity-duration stimulus space, thus identifying the optimal voltage-controlled pulse (‑2.4 V, 0.88 ms). The identified optimal voltage pulse can activate at least 65% of potentially responsive RGCs in both mouse strains. Furthermore, this pulse is well within the range of stimuli demonstrated to be safe and effective for retinal implant patients. Such optimized stimuli and the underlying method used to identify them support a high yield of responsive RGCs and will serve as an effective guideline for future in vitro investigations
Chiang, Hsueh-Sheng; Eroh, Justin; Spence, Jeffrey S; Motes, Michael A; Maguire, Mandy J; Krawczyk, Daniel C; Brier, Matthew R; Hart, John; Kraut, Michael A
How the brain combines the neural representations of features that comprise an object in order to activate a coherent object memory is poorly understood, especially when the features are presented in different modalities (visual vs. auditory) and domains (verbal vs. nonverbal). We examined this question using three versions of a modified Semantic Object Retrieval Test, where object memory was probed by a feature presented as a written word, a spoken word, or a picture, followed by a second feature always presented as a visual word. Participants indicated whether each feature pair elicited retrieval of the memory of a particular object. Sixteen subjects completed one of the three versions (N=48 in total) while their EEG were recorded simultaneously. We analyzed EEG data in four separate frequency bands (delta: 1-4Hz, theta: 4-7Hz; alpha: 8-12Hz; beta: 13-19Hz) using a multivariate data-driven approach. We found that alpha power time-locked to response was modulated by both cross-modality (visual vs. auditory) and cross-domain (verbal vs. nonverbal) probing of semantic object memory. In addition, retrieval trials showed greater changes in all frequency bands compared to non-retrieval trials across all stimulus types in both response-locked and stimulus-locked analyses, suggesting dissociable neural subcomponents involved in binding object features to retrieve a memory. We conclude that these findings support both modality/domain-dependent and modality/domain-independent mechanisms during semantic object memory retrieval.
Nokia, Miriam S; Waselius, Tomi; Mikkonen, Jarno E; Wikgren, Jan; Penttonen, Markku
Hippocampal θ (3-12 Hz) oscillations are implicated in learning and memory, but their functional role remains unclear. We studied the effect of the phase of local θ oscillation on hippocampal responses to a neutral conditioned stimulus (CS) and subsequent learning of classical trace eyeblink conditioning in adult rabbits. High-amplitude, regular hippocampal θ-band responses (that predict good learning) were elicited by the CS when it was timed to commence at the fissure θ trough (Trough group). Regardless, learning in this group was not enhanced compared with a yoked control group, possibly due to a ceiling effect. However, when the CS was consistently presented to the peak of θ (Peak group), hippocampal θ-band responding was less organized and learning was retarded. In well-trained animals, the hippocampal θ phase at CS onset no longer affected performance of the learned response, suggesting a time-limited role for hippocampal processing in learning. To our knowledge, this is the first study to demonstrate that timing a peripheral stimulus to a specific phase of the hippocampal θ cycle produces robust effects on the synchronization of neural responses and affects learning at the behavioral level. Our results support the notion that the phase of spontaneous hippocampal θ oscillation is a means of regulating the processing of information in the brain to a behaviorally relevant degree.
Tambeli, Claudia H; Levine, Jon D; Gear, Robert W
The duration of noxious stimulus-induced antinociception (NSIA) has been shown to outlast the pain stimulus that elicited it, however, the mechanism that determines the duration of analgesia is unknown. We evaluated the role of spinal excitatory and inhibitory receptors (NMDA, mGluR(5), mu-opioid, GABA(A), and GABA(B)), previously implicated in NSIA initiation, in its maintenance. As in our previous studies, the supraspinal trigeminal jaw-opening reflex (JOR) in the rat was used for nociceptive testing because of its remoteness from the region of drug application, the lumbar spinal cord. NSIA was reversed by antagonists for two inhibitory receptors (GABA(B) and mu-opioid) but not by antagonists for either of the two excitatory receptors (NMDA and mGluR(5)), indicating that NSIA is maintained by ongoing activity at inhibitory synapses in the spinal cord. Furthermore, spinal administration of the GABA(B) agonist baclofen mimicked NSIA in that it could be blocked by prior injection of the mu-opioid receptor antagonist H-D-Phe-Cys-Tyr-D-Trp-Arg-Thr-Pen-Thr-NH(2) (CTAP) in nucleus accumbens. CTAP also blocked baclofen antinociception when administered in the spinal cord. We conclude that analgesia induced by noxious stimulation is maintained by activity in spinal inhibitory receptors.
Kent, A. R.; Grill, W. M.
The clinical efficacy of deep brain stimulation (DBS) for the treatment of movement disorders depends on the identification of appropriate stimulation parameters. Since the mechanisms of action of DBS remain unclear, programming sessions can be time consuming, costly and result in sub-optimal outcomes. Measurement of electrically evoked compound action potentials (ECAPs) during DBS, generated by activated neurons in the vicinity of the stimulating electrode, could offer insight into the type and spatial extent of neural element activation and provide a potential feedback signal for the rational selection of stimulation parameters and closed-loop DBS. However, recording ECAPs presents a significant technical challenge due to the large stimulus artefact, which can saturate recording amplifiers and distort short latency ECAP signals. We developed DBS-ECAP recording instrumentation combining commercial amplifiers and circuit elements in a serial configuration to reduce the stimulus artefact and enable high fidelity recording. We used an electrical circuit equivalent model of the instrumentation to understand better the sources of the stimulus artefact and the mechanisms of artefact reduction by the circuit elements. In vitro testing validated the capability of the instrumentation to suppress the stimulus artefact and increase gain by a factor of 1000 to 5000 compared to a conventional biopotential amplifier. The distortion of mock ECAP (mECAP) signals was measured across stimulation parameters, and the instrumentation enabled high fidelity recording of mECAPs with latencies of only 0.5 ms for DBS pulse widths of 50 to 100 µs/phase. Subsequently, the instrumentation was used to record in vivo ECAPs, without contamination by the stimulus artefact, during thalamic DBS in an anesthetized cat. The characteristics of the physiological ECAP were dependent on stimulation parameters. The novel instrumentation enables high fidelity ECAP recording and advances the potential use
Carstens, E; Ansley, D
1. The aim of this study was to develop a quantitative behavioral model of nociception. Electromyographic (EMG) recordings from a hamstring flexor muscle provided a measure of the magnitude of hindlimb withdrawals elicited by brief, graded noxious contact thermal stimuli applied to the hindpaw in conscious rats. 2. The magnitude of limb withdrawals showed a significant, usually linear, increase with stimulus temperature from a threshold of approximately 40 up to 52 degrees C. Stimulus-response functions of withdrawal magnitude versus temperature were reproducible within and across rats. Withdrawal magnitude was much more tightly correlated with stimulus temperature (r2 = 0.76, 0.73) than was withdrawal latency (r2 = 0.57, 0.55). 3. Systemic administration of the opiate analgesic morphine (3.5 mg/kg ip) suppressed withdrawals in a naloxone-reversible manner, such that the slope of the stimulus-response function was significantly reduced without an increase in threshold. 4. Successive withdrawals to repeated, identical noxious heat stimuli decreased in a manner consistent with habituation. The response recovered to the prehabituated level after a 15-min rest period, and subsequently decremented even more quickly. The decrement in withdrawal magnitude was greater at lower stimulus intensities and shorter interstimulus intervals, and transferred to a nearby (7.5 mm) but not distant (2.5 cm) site. Evidence for dishabituation was also obtained. 5. The advantages of this method as an animal model of nociception are presented and discussed in terms of the underlying neural circuitry and its modulation.
Pérez-González, L A
Four adults were trained, using instructions and a matching-to-sample procedure, to select Stimulus B1 in the presence of Stimulus A1, B2 in the presence of A2, and B3 in the presence of A3 (the AB relations). Analogous PQ relations were trained. Afterwards, one stimulus in Set A and another stimulus in Set B appeared together as a sample, and novel Stimuli X1 and X2 were the comparisons. Responses to X1 were reinforced if the two stimuli in the sample had been related in the previous training (e.g., A1 and B1), and responses to X2 were reinforced if the two samples had not been related (e.g., A1 and B2). These were the ABX relations. In a test in which a stimulus of Set P and another of Set Q were the samples and X1 and X2 were the comparisons, 2 subjects selected X1 when the samples were P1 and Q1, P2 and Q2, and P3 and Q3, and selected X2 in the presence of the other six sample combinations (P1Q2, P1Q3, P2Q1, P2Q3, P3Q1, and P3Q2). Another subject showed the same responding after additional training. In the second experiment, 3 adults and an 11-year-old child were trained on AB, PQ, and ABX relations, and they showed the symmetrical relations BA and QP upon testing. Then all 4 of these subjects responded accurately to the PQX test. Results of Experiments 1 and 2 showed novel, consistent comparison selection based on the previously established relation between the two stimuli in the sample. In a third experiment, 3 of the subjects who had shown PQX relations were trained on EFX relations, with pairs of E and F stimuli as samples and X stimuli as comparisons. When the EF relations were tested, all 3 subjects consistently selected F1 in the presence of E1, F2 in the presence of E2, and F3 in the presence of E3 from the first trial. The results of Experiment 3 showed novel stimulus relations after training with a more complex conditional discrimination format. PMID:8207356
DeSimone, Jesse C; Everling, Stefan; Heath, Matthew
The presentation of a remote - but not proximal - distractor concurrent with target onset increases prosaccade reaction times (RT) (i.e., the remote distractor effect: RDE). The competitive integration model asserts that the RDE represents the time required to resolve the conflict for a common saccade threshold between target- and distractor-related saccade generating commands in the superior colliculus. To our knowledge however, no previous research has examined whether remote and proximal distractors differentially influence antisaccade RTs. This represents a notable question because antisaccades require decoupling of the spatial relations between stimulus and response (SR) and therefore provide a basis for determining whether the sensory- and/or motor-related features of a distractor influence response planning. Participants completed pro- and antisaccades in a target-only condition and conditions wherein the target was concurrently presented with a proximal or remote distractor. As expected, prosaccade RTs elicited a reliable RDE. In contrast, antisaccade RTs were increased independent of the distractor's spatial location and the magnitude of the effect was comparable across each distractor location. Thus, distractor-related antisaccade RT costs are not accounted for by a competitive integration between conflicting saccade generating commands. Instead, we propose that a visual distractor increases uncertainty related to the evocation of the response-selection rule necessary for decoupling SR relations.
Hollis, K L; Overmier, J B
In male Betta splendens, aggressive behavior is drastically attenuated following telencephalon ablation. Because instrumental training and Pavlovian conditioning experiments with intact fish have suggested that associative factors may play an important role in the performance of agonistic behaviors, the effect of ablation on instrumental learning and Pavlovian conditioning was studied. In Experiment 1, ablation had no effect on the learning of the instrumental tunnel-swimming response reinforced by mirror presentation (i.e., viewing a conspecific), although the mirror presentations in yoked-control groups elicited fewer responses in ablates than in normal and sham-operated control fish. Yoked controls further established that instrumental responding was maintained by the reinforcement contingency and was not merely the result of increased motor activity. Experiment 2 studied Pavlovian conditioning of the components of the agonistic display. Unconditioned fin erection, gill erection, and tail beating (i.e., unconditioned responses, URs) to the mirror US all were less frequent in ablates than in normals or shams. Of these, only gill cover erection showed evidence of true conditioning (i.e., conditioned responses; CRs) in which responses to the conditioned stimulus (CS) are due to the pairings of CS and US (unconditioned stimulus). However, ablates suffered no impairment of conditioned gill erections. Ablates performed fewer fin erections to the CS; however, fin erection responses were not due to CS-US pairings but were attributable to pseudoconditioning. These results are related to hypotheses postulating the involvement of learning mechanisms in ablation-produced deficits and normal aggressive behavior.
Lye, Jenny; Hirschberg, Joe
In late 2008 and early 2009 the Australian Federal Government introduced a series of economic stimulus packages designed to maintain consumer spending in the early days of the Great Recession. When these packages were initiated the media suggested that the wide-spread availability of electronic gaming machines (EGMs, e.g. slot machines, poker machines, video lottery terminals) in Australia would result in stimulating the EGMs. Using state level monthly data we estimate that the stimulus packages led to an increase of 26 % in EGM revenues. This also resulted in over $60 million in additional tax revenue for State Governments. We also estimate a short-run aggregate income demand elasticity for EGMs to be approximately 2.
Weintraub, S; Mesulam, M M
Patients with unilateral hemispheric lesions were given visual target cancellation tasks. As expected, marked contralateral and less severe ipsilateral visual inattention were observed in patients with right-sided cerebral lesions whereas those with left-sided lesions showed only mild contralateral neglect. Stimulus material (shapes vs letters) and array (random vs structured) interacted in a complex manner to influence target detection only in patients with right-sided lesions. Furthermore, the search strategy of these patients tended to be erratic, particularly when the stimuli were in an unstructured array. A structured array prompted a more systematic and efficient search. It appears, therefore, that stimulus content and spatial array affect neglect behaviour in patients with right-sided lesions and that a lack of systematic visual exploration within the extrapersonal space is one factor that contributes to visual hemispatial inattention.
Huckauf, Anke; Nazir, Tatjana A
Processes underlying crowding in visual letter recognition were examined by investigating effects of training. Experiment 1 revealed that training reduces crowding mainly for trained strings. This was corroborated in Experiment 2, where no training effects were obvious after 3 days of training when strings changed from trial to trial. Experiment 3 specified that after a short amount of training, learning effects remained specific to trained strings and also to the trained retinal eccentricity and the interletter spacing used in training. Transfer to other than trained conditions was observed only after further training. Experiment 4 showed that transfer occurred earlier when words were used as stimuli. These results thus demonstrate that part of crowding results from the absence of higher level representations of the stimulus. Such representations can be acquired through learning visual properties of the stimulus.
Dube, W V; McIlvane, W J
Three individuals with mental retardation exhibited stimulus overselectivity in a delayed matching-to-sample task in which two sample stimuli were displayed on each trial. Intermediate accuracy scores indicated that participants could match one of the samples but not both of them. Accuracy in a baseline condition was compared to accuracy with a differential observing response procedure. This procedure prompted participants to make simultaneous identity-matching responses that required observation and discrimination of both sample stimuli. These observing responses were never followed by differential consequences. When observing responses were prompted, participants' accuracy scores improved. In a return to the baseline condition, when differential observing responses were no longer prompted, accuracy returned to intermediate levels. The results show that stimulus overselectivity can be greatly reduced by a behavioral intervention that controls observing behavior and verifies discrimination, but that exposure to such procedures alone may be insufficient for lasting benefits.
Minetto, Marco Alessandro; Botter, Alberto
To explore the efficacy of muscle motor point stimulation in eliciting muscle cramps, 11 subjects underwent eight sessions of electrical stimulation of the following muscles bilaterally: abductor hallucis flexor hallucis brevis, and both heads of the gastrocnemius muscles. Bursts of 150 square wave stimuli (duration: 152 micros; current intensity: 30% supramaximal) were applied. The stimulation frequency was increased from 4 pulses per second (pps) at increments of 2 pps until a cramp was induced. The number of cramps that could be elicited was smaller in flexor hallucis brevis than in abductor hallucis (16 vs. 22 out of 22 trials each; P < 0.05) and in the lateral gastrocnemius than in the medial gastrocnemius (5 vs. 20 out of 22 trials each; P < 0.0001). We show that leg and foot muscles have different cramp susceptibility, and the intermuscle variability in the elicitability profile for electrically induced cramps supports the use of the proposed method for cramp research.
McElroy, J F; O'Donnell, J M
Thirty rats were trained to discriminate the centrally acting beta adrenergic agonist clenbuterol (0.1 mg/kg) from saline using a water-reinforced (fixed-ratio 10 schedule) two-lever operant task. Discrimination acquisition required a mean +/- S.E.M. of 42 +/- 7 training sessions (median of 26 training sessions). The clenbuterol stimulus was dose-dependent (ED50 = 0.03 mg/kg) and stereoselective, and had a rapid onset (5 min) and a duration of approximately 1 hr. The beta adrenergic antagonist propranolol fully antagonized the clenbuterol discriminative stimulus (IC50 = 0.18 mg/kg). Other beta adrenergic agonists such as SOM 1122 (ED50 = 0.01 mg/kg), zinterol (ED50 = 0.03 mg/kg), salbutamol (ED50 = 0.23 mg/kg) and prenalterol (ED50 = 1.91 mg/kg) substituted for clenbuterol. The monoamine uptake inhibitor despiramine (ED50 = 2.25 mg/kg), the psychomotor stimulants amphetamine (ED50 = 0.33 mg/kg) and pentylenetetrazol (ED50 = 0.31 mg/kg), and the dopamine receptor antagonists haloperidol (ED50 = 0.08 mg/kg) and chlorpromazine (ED50 = 2.32 mg/kg) similarly substituted for clenbuterol. However, chlordiazepoxide, pentobarbital, fentanyl, cocaine and fenfluramine produced little or no clenbuterol lever selection up to doses that decreased response rate markedly. The ability of SOM 1122, zinterol, salbutamol, despiramine, amphetamine, pentylenetetrazol and haloperiol to substitute for the clenbuterol stimulus was antagonized by prior treatment with propranolol. Taken together, these results suggest that the discriminative stimulus properties of clenbuterol are mediated, at least in part, through an interaction with beta adrenergic receptors. The same drugs also were assayed for in vitro inhibition of [125I]iodopindolol binding to beta adrenergic receptor preparations of rat cerebral cortex and cerebellum.(ABSTRACT TRUNCATED AT 250 WORDS)
Shelton, Keith L.; Nicholson, Katherine L.
In vitro studies show that the abused inhalant toluene affects a number of ligand-gated ion channels. The two most consistently implicated of these are γ-aminobutyric acid type A (GABAA) receptors which are positively modulated by toluene and N-methyl-D-aspartate (NMDA) receptors which are negatively modulated by toluene. Behavioral studies also suggest an interaction of toluene with GABAA and/or NMDA receptors but it is unclear if these receptors underlie the abuse-related intoxicating effects of toluene. Seventeen B6SJLF1/J mice were trained using a two-choice operant drug discrimination procedure to discriminate 10 min of exposure to 2000 ppm toluene vapor from 10 min of exposure to air. The discrimination was acquired in a mean of 65 training sessions. The stimulus effects of 2000 ppm toluene vapor were exposure concentration-dependent but rapidly diminished following the cessation of vapor exposure. The stimulus effects of toluene generalized to the chlorinated hydrocarbon vapor perchloroethylene but not 1,1,2-trichloroethane nor the volatile anesthetic isoflurane. The competitive NMDA antagonist CGS-17955, the uncompetitive antagonist dizocilpine and the glycine-site antagonist L701,324 all failed to substitute for toluene. The classical nonselective benzodiazepines midazolam and chlordiazepoxide produced toluene-like stimulus effects but the alpha 1 subunit preferring positive GABAA modulator zaleplon failed to substitute for toluene. The barbiturates pentobarbital and methohexital and the GABAA-positive modulator neurosteroid allopregnanolone did not substitute for toluene. These data suggest that the stimulus effects of toluene may be at least partially mediated by benzodiazepine-like positive allosteric modulation of GABAA receptors containing alpha 2, 3 or 5 subunits. PMID:24436974
AD_________________ Award Number: W81XWH-08-1-0755 TITLE: Importance of Virtual Reality to a...Importance of Virtual Reality to a Controlled Stimulus 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-08-1-0755 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR... Virtual Reality (VR) simulator used in Virtual Reality Exposure Therapy (VRET) is the active component when using the technique to treat combat
Olsson, Shannon B; Kuebler, Linda S; Veit, Daniel; Steck, Kathrin; Schmidt, Alexandra; Knaden, Markus; Hansson, Bill S
Olfactory studies have expanded beyond the study of single compound odor perception to explore the processing of complex mixtures and blends. The spatiotemporal presentation of blend stimuli is a challenging task requiring volatiles with diverse chemical and physical properties to be presented as a unified stimulus. This not only necessitates accurate control of the timing and homogeneity of the odor stream, but requires attention to the concentration of each blend component presented. We have developed a novel, multicomponent stimulus system for use in olfactory experiments that is capable of presenting up to 8 different odors simultaneously or in sequence at defined concentrations and time scales. Each odor is separated to minimize physical or chemical interactions, and stimulations are performed from a saturated headspace of the odor solution. Stimulus concentrations can be measured empirically or estimated using common gas laws. Photoionization detector measurements show that stimuli could be presented as cohesive blends or single components at frequencies of at least 10Hz without leakage or contamination. Solid phase microextraction measurements also show that the concentration of each component could be equilibrated through regulation of each component line's flow rate based on the different partial vapor pressures of the odorants. This device provides a unique method for introducing complex volatile mixtures for olfactory studies in a variety of animal taxa and allows for accurate control of odor intensities in both time and space.
Soppimath, K S; Aminabhavi, T M; Dave, A M; Kumbar, S G; Rudzinski, W E
Recently, there has been a great deal of research activity in the development of stimulus-responsive polymeric hydrogels. These hydrogels are responsive to external or internal stimuli and the response can be observed through abrupt changes in the physical nature of the network. This property can be favorable in many drug delivery applications. The external stimuli can be temperature, pH, ionic strength, ultrasonic sound, electric current, etc. A majority of the literature related to the development of stimulus-responsive drug delivery systems deals with temperature-sensitive poly(N-isopropyl acrylamide) (pNIPAAm) and its various derivatives. However, acrylic-based pH-sensitive systems with weakly acidic/basic functional groups have also been widely studied. Quite recently, glucose-sensitive hydrogels that are responsive to glucose concentration have been developed to monitor the release of insulin. The present article provides a brief introduction and recent developments in the area of stimulus-responsive hydrogels, particularly those that respond to temperature and pH, and their applications in drug delivery.
Ohmae, Shogo; Tanaka, Masaki
Although we can detect slight changes in musical rhythm, the underlying neural mechanism remains elusive. Here we show that two distinct mechanisms are automatically selected depending on the speed of the rhythm. When human subjects detected a single omission of isochronous repetitive auditory stimuli, reaction time strongly depended on the stimulus onset asynchrony (SOA) for shorter SOAs (<250 ms), but was almost constant for longer SOAs. For shorter SOAs, subjects were unable to detect stimulus omission when either monaural stimuli or those in different frequencies were randomly presented. In contrast, for longer SOAs, reaction time increased when different tempos were presented simultaneously to different ears. These results suggest that depending on the speed of rhythms, the brain may use either temporal grouping of discrete sounds or temporal prediction of upcoming stimuli to detect the absence of a regular stimulus. Because we also found a similar relationship between reaction time and SOA for both visual and tactile stimuli, dual detection strategies could be generalized to other sensory modalities. PMID:26847381
Appelbaum, L.G.; Smith, D.V.; Boehler, C.N.; Chen, W.D.; Woldorff, M.G.
Humans are constantly confronted with environmental stimuli that conflict with task goals and can interfere with successful behavior. Prevailing theories propose the existence of cognitive control mechanisms that can suppress the processing of conflicting input and enhance that of the relevant input. However, the temporal cascade of brain processes invoked in response to conflicting stimuli remains poorly understood. By examining evoked electrical brain responses in a novel, hemifield-specific, visual-flanker task, we demonstrate that task-irrelevant conflicting stimulus input is quickly detected in higher-level executive regions while simultaneously inducing rapid, recurrent modulation of sensory processing in the visual cortex. Importantly, however, both of these effects are larger for individuals with greater incongruency-related reaction time slowing. The combination of neural activation patterns and behavioral interference effects suggest that this initial sensory modulation induced by conflicting stimulus inputs reflects performance-degrading attentional distraction due to their incompatibility, rather than any rapid task-enhancing cognitive control mechanisms. The present findings thus provide neural evidence for a model in which attentional distraction is the key initial trigger for the temporal cascade of processes by which the human brain responds to conflicting stimulus input in the environment. PMID:20849233
Fey, Werner; Moggi, Franz; Rohde, Kristina B; Michel, Chantal; Seitz, Andrea; Stein, Maria
The availability of appropriate stimulus material is a key concern for an experimental approach to research on alcohol use disorders (AUDs). A large number of such stimuli are necessary to evoke relevant alcohol-related associations. We report the development of a large stimulus database consisting of 457 pictures of alcoholic beverages and 398 pictures of neutral objects. These stimuli were rated by 18 inpatients hospitalized due to severe AUD and 18 healthy controls along four dimensions: arousal, valence, alcohol-relatedness, and craving. Physical parameters of the pictures were assessed. After outlier removal, 831 stimuli that were characterized as either alcohol-related or neutral were retained in the final stimulus pool. Alcohol-related pictures (versus neutral pictures) evoked higher arousal, more craving and were judged to have higher alcohol-relatedness and a more negative valence. Group comparisons indicated that in patients, neutral pictures evoked more craving and had higher alcohol-relatedness than they did in controls. Physical parameters such as visual complexity, luminance, and color were extracted from these pictures, and extreme values were normalized to minimize mean differences between alcoholic and neutral stimuli. The pictures met the qualitative requirements for (neurophysiological) research. A data file containing rating values and physical parameters will be provided upon request.
Urcuioli, Peter J.; Jones, B. Max; Lionello-DeNolf, Karen M.
Response membership in pigeons’ stimulus class formation was evaluated using associative symmetry and class expansion tests. In Experiment 1, pigeons learned hue-hue (AA) and form-form (BB) successive matching plus a modified hue-form (AB) task in which reinforcement was contingent upon a left versus right side-key response after the positive AB sequences. On subsequent BA (symmetry) probe trials, pigeons responded more often to the comparisons on the reverse of the positive than negative AB sequences and, more importantly, preferentially pecked the side key consistent with symmetry after the reversed positive sequences. In Experiment 2, the original three baseline tasks were supplemented by dot-white (CC) successive matching in which reinforcement was contingent upon a left versus right side-key response after the positive CC sequences. Class expansion was then tested by presenting non-reinforced CA and CB successive matching probes. Comparison response rates were mostly non-differential on CA probes but were uniformly higher on CB probes that consisted of the C samples and B comparisons from the same, hypothesized class. Together, these results provide evidence that responses can become members of stimulus classes, as predicted by Urcuioli’s (2008) theory of pigeons’ stimulus-class formation and Sidman’s (2000) theory of equivalence. PMID:23413094
Gatch, Michael B; Taylor, Cynthia M; Forster, Michael J
A number of psychostimulant-like cathinone compounds are being sold as 'legal' alternatives to methamphetamine or cocaine. The purpose of these experiments was to determine whether cathinone compounds stimulate motor activity and have discriminative stimulus effects similar to those of cocaine and/or methamphetamine. 3,4-Methylenedioxypyrovalerone (MDPV), methylone, mephedrone, naphyrone, flephedrone, and butylone were tested for locomotor stimulant effects in mice and subsequently for substitution in rats trained to discriminate cocaine (10 mg/kg, intraperitoneally) or methamphetamine (1 mg/kg, intraperitoneally) from saline. All compounds fully substituted for the discriminative stimulus effects of cocaine and methamphetamine. Several commonly marketed cathinones produce discriminative stimulus effects comparable with those of cocaine and methamphetamine, which suggests that these compounds are likely to have similar abuse liabilities. MDPV and naphyrone produced locomotor stimulant effects that lasted much longer than those of cocaine or methamphetamine and therefore may be of particular concern, particularly because MDPV is one of the most commonly found substances associated with emergency room visits because of adverse effects of taking 'bath salts'.
Jitsumori, Masako; Sugimoto, Sukeo
Six pigeons served in a discrete-trial experiment on short-term memory. Combinations of three key positions and two ordinal positions, yielding six possible sequences of stimulus-response pairs, were used as lists of items. A retention interval separated list presentation from the test phase in which two (for Group 1) or three (for Group 2) keys were illuminated with either red or green light. A reinforcer was delivered if a subject pecked the key of the first item on a red trial and the key of the second item on a green trial. When the retention interval was lengthened from one to five or nine seconds, a systematic loss of stimulus control resulted. Lengthening the interval between items from one to eight seconds had a much smaller effect for the birds in Group 1, whereas a systematic loss of stimulus control was found in red trials for the birds in Group 2. The functional relations between choice accuracy and delay provided an empirical basis for analysis of what relations among temporal events can become discriminative stimuli. PMID:16812285
Liu, Xiao; Zhu, Xiao-Hong; Chen, Wei
To investigate whether individuals' ongoing neuronal activity at resting state can affect their response to brain stimulation, fMRI BOLD signals were imaged from the human visual cortex of fifteen healthy subjects in the absence and presence of visual stimulation. It was found that the temporal correlation strength but not amplitude of baseline BOLD signal fluctuations acquired under the eyes-fixed condition is positively correlated with the amplitude of stimulus-evoked BOLD responses across subjects. Moreover, the spatiotemporal correlations of baseline BOLD signals imply a coherent network covering the visual system, which is topographically indistinguishable from the "resting-state visual network" observed under the eyes-closed condition. The overall findings suggest that the synchronization of ongoing brain activity plays an important role in determining stimulus-evoked brain activity even at an early stage of the sensory system. The tight relationship between baseline BOLD correlation and stimulus-evoked BOLD amplitude provides an essential basis for understanding and interpreting the large inter-subject BOLD variability commonly observed in numerous fMRI studies and potentially for improving group fMRI analysis. This study highlights the importance to integrate the information from both resting-state coherent networks and task-evoked neural responses for a better understanding of how the brain functions.
Barot, Sabiha K; Kyono, Yasuhiro; Clark, Emily W; Bernstein, Ilene L
A central feature of models of associative memory formation is the reliance on information convergence from pathways responsive to the conditioned stimulus (CS) and unconditioned stimulus (US). In particular, cells receiving coincident input are held to be critical for subsequent plasticity. Yet identification of neurons in the mammalian brain that respond to such coincident inputs during a learning event remains elusive. Here we use Arc cellular compartmental analysis of temporal gene transcription by fluorescence in situ hybridization (catFISH) to locate populations of neurons in the mammalian brain that respond to both the CS and US during training in a one-trial learning task, conditioned taste aversion (CTA). Individual neurons in the basolateral nucleus of the amygdala (BLA) responded to both the CS taste and US drug during conditioning. Coincident activation was not evident, however, when stimulus exposure was altered so as to be ineffective in promoting learning (backward conditioning, latent inhibition). Together, these data provide clear visualization of neurons in the mammalian brain receiving convergent information about the CS and US during acquisition of a learned association.
Rudy, Jerry W.; And Others
Repeated, isolated presentations of a stimulus typically reduce the subsequent ability of that cue to become an effective conditioned stimulus. This phenomenon is known as the latent inhibition effect. Four experiments investigate this effect. (Editor/RK)
Ward-Fear, Georgia; Thomas, Jai; Webb, Jonathan K; Pearson, David J; Shine, Richard
Conditioned taste aversion (CTA) is an adaptive learning mechanism whereby a consumer associates the taste of a certain food with symptoms caused by a toxic substance, and thereafter avoids eating that type of food. Recently, wildlife researchers have employed CTA to discourage native fauna from ingesting toxic cane toads (Rhinella marina), a species that is invading tropical Australia. In this paper, we compare the results of 2 sets of CTA trials on large varanid lizards ("goannas," Varanus panoptes). One set of trials (described in this paper) exposed recently-captured lizards to sausages made from cane toad flesh, laced with a nausea-inducing chemical (lithium chloride) to reinforce the aversion response. The other trials (in a recently-published paper, reviewed herein) exposed free-ranging lizards to live juvenile cane toads. The effectiveness of the training was judged by how long a lizard survived in the wild before it was killed (fatally poisoned) by a cane toad. Both stimuli elicited rapid aversion to live toads, but the CTA response did not enhance survival rates of the sausage-trained goannas after they were released into the wild. In contrast, the goannas exposed to live juvenile toads exhibited higher long-term survival rates than did untrained conspecifics. Our results suggest that although it is relatively easy to elicit short-term aversion to toad cues in goannas, a biologically realistic stimulus (live toads, encountered by free-ranging predators) is most effective at buffering these reptiles from the impact of invasive toxic prey.
Ambrosecchia, Marianna; Marino, Barbara F. M.; Gawryszewski, Luiz G.; Riggio, Lucia
Stimulus position is coded even if it is task-irrelevant, leading to faster response times when the stimulus and the response locations are compatible (spatial Stimulus–Response Compatibility–spatial SRC). Faster responses are also found when the handle of a visual object and the response hand are located on the same side; this is known as affordance effect (AE). Two contrasting accounts for AE have been classically proposed. One is focused on the recruitment of appropriate grasping actions on the object handle, and the other on the asymmetry in the object shape, which in turn would cause a handle-hand correspondence effect (CE). In order to disentangle these two accounts, we investigated the possible transfer of practice in a spatial SRC task executed with a S–R incompatible mapping to a subsequent affordance task in which objects with either their intact handle or a broken one were used. The idea was that using objects with broken handles should prevent the recruitment of motor information relative to object grasping, whereas practice transfer should prevent object asymmetry in driving handle-hand CE. A total of three experiments were carried out. In Experiment 1 participants underwent an affordance task in which common graspable objects with their intact or broken handle were used. In Experiments 2 and 3, the affordance task was preceded by a spatial SRC task in which an incompatible S–R mapping was used. Inter-task delays of 5 or 30 min were employed to assess the duration of transfer effect. In Experiment 2 objects with their intact handle were presented, whereas in Experiment 3 the same objects had their handle broken. Although objects with intact and broken handles elicited a handle-hand CE in Experiment 1, practice transfer from an incompatible spatial SRC to the affordance task was found in Experiment 3 (broken-handle objects), but not in Experiment 2 (intact-handle objects). Overall, this pattern of results indicate that both object asymmetry and
Velázquez-Martínez, D N; López Cabrera, M; Sánchez, H; Ramírez, J I; Hong, E
OBJECTIVE: To determine whether indorenate, a serotonin-receptor agonist, can exert discriminative control over operant responses, to establish the temporal course of discriminative control and to compare its stimulus properties to a (5-HT)IA receptor agonist. [3H]-8-hydroxy-2-(di-N-propylamino) tetralin (8-OH-DPAT). DESIGN: Prospective animal study. ANIMALS: Ten male Wistar rats. INTERVENTIONS: Rats were trained to press either of 2 levers for sucrose solution according to a fixed ratio schedule, which was gradually increased. Rats were given injections of either indorenate or saline solution during discrimination training. Once they had achieved an 83% accuracy rate, rats underwent generalization tests after having received a different dose of indorenate, the training dose of indorenate at various intervals before the test, various doses of 8-OH-DPT, or NAN-190 administered before indorenate or 8-OH-DPAT. OUTCOME MEASURES: Distribution of responses between the 2 levers before the first reinforcer of the session, response rate for all the responses in the session, and a discrimination index that expressed the drug-appropriate responses as a proportion of the total responses. RESULTS: Indorenate administration resulted in discriminative control over operant responses, maintained at fixed ratio 10, at a dose of 10.0 mg/kg (but not 3.0 mg/kg). When the interval between the administration of indorenate and the start of the session was varied, the time course of its cue properties followed that of its described effects on 5-HT turnover. In generalization tests, the discrimination index was a function of the dose of indorenate employed; moreover, administration of 8-OH-DPAT (from 0.1 to 1.0 mg/kg) fully mimicked the stimulus properties of indorenate in a dose-dependent way. The (5-HT)IA antagonist NAN-190 prevented the stimulus generalization from indorenate to 8-OH-DPAT. Also, NAN-190 antagonized the stimulus control of indorenate when administered 45 minutes before
Tian, Dai-Shi; Xiong, Jin; Pan, Qing; Liu, Fang; Wang, Lu; Xu, Sha-Bei; Huang, Guang-Ying; Wang, Wei
Objectives. De qi is the subjective constellation of sensations perceived by the acupuncturists and patients as described in several literatures, but the absence of quantitative evaluation methods in de qi restricts the use of acupuncture treatment widely in the world. In the present study, we tried to investigate the intrinsic property of de qi is and how evaluate it quantitatively. Methods. 30 healthy adult volunteers were determined to investigate intrinsic changes in the human body after acupuncture with de qi. Results. Acupuncture treatment with de qi apparently increased acupoint blood flow, tissue displacement, and the amplitude of myoelectricity after de qi on acupoints. Furthermore, acupuncture treatment induced fMRI signal increase/decrease in different brain regions although no significant change in electroencephalography. Interpretation. The intrinsic change of the subjects representing the specific response of acupoints and human brain to acupuncture indicated that de qi might be evaluated quantitatively by those above aspects, which facilitated the confirmation in validity and propagation of this treatment modality widely in the world.
Foo, H; Helmstetter, F J
The present study investigated the role of micro, delta, and kappa receptors within the RVM in mediating expression of conditional hypoalgesia (CHA). Five groups of rats with RVM cannulae were given daily sessions of paired or unpaired presentations of an auditory CS (white noise) and foot shock across three consecutive days. On the test day, rats in the Paired condition were injected with the micro antagonist CTAP, the delta antagonist naltrindole, the kappa antagonist nor-BNI, or saline. Rats in the Unpaired condition were injected with saline. TFLs were measured before and after injections, as well as during and after presentations of the CS. The results showed that none of the drugs affected baseline TFLs. During CS presentation, rats in the Paired condition injected with saline showed longer TFLs than those in the Unpaired condition given saline, confirming the presence of CHA. Expression of this response was blocked by CTAP, but was unaffected by naltrindole or nor-BNI. These results suggest that mu, but not delta or kappa, opioid receptors in the RVM mediate expression of CHA.
Xu, Yifang; Collins, Leslie M
This work investigates dynamic range and intensity discrimination for electrical pulse-train stimuli that are modulated by noise using a stochastic auditory nerve model. Based on a hypothesized monotonic relationship between loudness and the number of spikes elicited by a stimulus, theoretical prediction of the uncomfortable level has previously been determined by comparing spike counts to a fixed threshold, Nucl. However, no specific rule for determining Nucl has been suggested. Our work determines the uncomfortable level based on the excitation pattern of the neural response in a normal ear. The number of fibers corresponding to the portion of the basilar membrane driven by a stimulus at an uncomfortable level in a normal ear is related to Nucl at an uncomfortable level of the electrical stimulus. Intensity discrimination limens are predicted using signal detection theory via the probability mass function of the neural response and via experimental simulations. The results show that the uncomfortable level for pulse-train stimuli increases slightly as noise level increases. Combining this with our previous threshold predictions, we hypothesize that the dynamic range for noise-modulated pulse-train stimuli should increase with additive noise. However, since our predictions indicate that intensity discrimination under noise degrades, overall intensity coding performance may not improve significantly.
Marrero, Héctor G; Lemos, José R
Peptidergic nerve terminals of the neurohypophysis (NH) secrete both oxytocin and vasopressin upon stimulation with peptide-specific bursts of action potentials from magnocellular neurons. These bursts vary in both frequency and action potential duration and also induce in situ ionic changes both inside and outside the terminals in the NH. These temporary effects include the increase of external potassium and decrease of external calcium, as well as the increase in internal sodium and chloride concentrations. In order to determine any mechanism of action that these ionic changes might have on secretion, stimulus-induced capacitance recordings were performed on isolated terminals of the NH using action potential burst patterns of varying frequency and action potential width. The results indicate that in NH terminals: (1) increased internal chloride concentration improves the efficiency of action potential-induced capacitance changes, (2) increasing external potassium increases stimulus-induced capacitance changes, (3) decreasing external calcium decreases the capacitance induced by low frequency broadened action potentials, while no capacitance change is observed with high frequency un-broadened action potentials, and (4) increasing internal sodium increases the capacitance change induced by low frequency bursts of broadened action potentials, more than for high frequency bursts of narrow action potentials. These results are consistent with previous models of stimulus-induced secretion, where optimal secretory efficacy is determined by particular characteristics of action potentials within a burst. Our results suggest that positive effects of increased internal sodium and external potassium during a burst may serve as a compensatory mechanism for secretion, counterbalancing the negative effects of reduced external calcium. In this view, high frequency un-broadened action potentials (initial burst phase) would condition the terminals by increasing internal sodium for
Klapp, Stuart T.; Greenberg, Lisa A.
Some types of automaticity can be attributed to simple stimulus-response associations (G. D. Logan, 1988). This can be studied with paradigms in which associations to an irrelevant stimulus automatically influence responding to a relevant stimulus. In 1 example, the irrelevant and relevant stimuli were presented successively with the 1st,…
DeLeon, Iser G.; Iwata, Brian A.
A study of seven adults with profound developmental disabilities compared methods for presenting stimuli during reinforcer-preference assessments. It found that a multiple-stimulus format in which selections were made without replacement may share the advantages of a paired-stimulus format and a multiple-stimulus format with replacement, while…
Rieth, Sarah R.; Stahmer, Aubyn C.; Suhrheinrich, Jessica; Schreibman, Laura
Many individuals with autism spectrum disorders (ASD) display stimulus overselectivity, wherein a subset of relevant components in a compound stimulus controls responding, which impairs discrimination learning. The original experimental research on stimulus overselectivity in ASD was conducted several decades ago; however, interventions for…
Grose, John H.; Hall, Joseph W., III; Buss, Emily
This study examined the effects of cochlear hearing loss on the ability to discriminate increments in the duration of a stimulus under conditions where the frequency and/or amplitude of the stimulus change dynamically. Three stimulus types were used: pure tones, frequency-modulated tones, and narrow bands of noise. The carrier/center frequency of…
Liu, Pingping; Li, Xingshan; Han, Buxin
Eye movements of Chinese readers were recorded for sentences in which high- and low-frequency target words were presented normally or with reduced stimulus quality in two experiments. We found stimulus quality and word frequency produced strong additive effects on fixation durations for target words. The results demonstrate that stimulus quality…
Shabani, Daniel B.; Fisher, Wayne W.
Stimulus fading in the form of gradually increased exposure to a fear-evoking stimulus, often combined with differential reinforcement, has been used to treat phobias in children who are otherwise normal and in children with autism. In this investigation, we applied stimulus fading plus differential reinforcement with an adolescent with autism and…
Weiss, Stanley J.; Kearns, David N.; Antoshina, Maria
According to the composite-stimulus control model (Weiss, 1969, 1972b), an individual discriminative stimulus (S[superscript D]) is composed of that S[superscript D]'s on-state plus the off-states of all other relevant S[superscript D]s. The present experiment investigated the reversibility of composite-stimulus control. Separate groups of rats…
Salud, Jonathan; Ononye, Chiagozie; Salud, Lawrence; Pugh, Carla
In recent years, simulation training has emerged as an innovative method for decreasing error and teaching complex procedures. Simulation has also been a valuable tool for evaluating investigatory and analytic thinking. By adding a specific, clinically oriented modification to a commercially available simulator, we were able to elicit first-year emergency medicine resident perceptions, actions, and decisions.
Relative clauses have been implicated alternately as a strength and a weakness in the language of people with Williams Syndrome (WS). To clarify the facts, an elicited production test was administered to 10 people with WS (age 10-16 years), 10 typically developing children (age 4-7 years), and 12 typically developing adults. Nearly every WS…
Wu, Mei-Mei; Liu, Ying-Hsang
Explores how intermediaries seek information from patrons by analyzing intermediaries' elicitation utterances through three dimensions: linguistic forms, utterance purposes, and communicative functions. Reports on results of questionnaires given to patrons and intermediaries in academic and research libraries in Taiwan and investigates…
Schoon, Craig G.
The semantic differential was used to assess the properties of affect elicited by occupational stimuli. Vocationally committed men studying medicine, business, and engineering responded to a semantic differential containing occupational concepts. Results show a semantic space for all three groups composed of three orthogonal dimensions of affect…
Gilbert, John K.; And Others
An exposition is made of a method to elicit students' comprehension of the meaning of words commonly used in science, which may be influential in determining what they learn. The method's aim is to elucidate features in students' understanding of childrens' science (that found before formal teaching of science), student science (that found after…
Valverde, Miguel Rodriguez; Luciano, Carmen; Barnes-Holmes, Dermot
The present study investigates the transfer of aversively conditioned respondent elicitation through equivalence classes, using skin conductance as the measure of conditioning. The first experiment is an attempt to replicate Experiment 1 in Dougher, Augustson, Markham, Greenway, and Wulfert (1994), with different temporal parameters in the…
Hodges, Rosemary; Munro, Natalie; Baker, Elise; McGregor, Karla; Docking, Kimberley; Arciuli, Joanne
This study is about the role of elicited verbal imitation in toddler word learning. Forty-eight toddlers were taught eight nonwords linked to referents. During training, they were asked to imitate the nonwords. Naming of the referents was tested at three intervals (one minute later [uncued], five minutes, and 1-7 days later [cued]) and recognition…
Richard, Veronica M.; Lahman, Maria K. E.
In this methodological discussion, the authors detail and reflect on the processes of using photo-elicitation interviewing as a way to align with positive qualitative methodologies, to gain access to participant beliefs and values, and to highlight participant voices through their choices of words and visuals. A review of the literature and an…
Embracing the new sociology of childhood, this paper describes a participatory research method built on a belief in the competency of young children. The paper begins with a critical review of the photo elicitation literature exploring the varied levels of children's participation. Drawing on the strengths of the previous research, a multi-step…
Cox, Troy L.; Davies, Randall S.
This study examined the use of automatic speech recognition (ASR) scored elicited oral response (EOR) tests to assess the speaking ability of English language learners. It also examined the relationship between ASR-scored EOR and other language proficiency measures and the ability of the ASR to rate speakers without bias to gender or native…
Studied second language acquisition (SLA) designed with Web-based elicitation tasks to obtain greater internal and external validity. Tested the acquisition of the properties subsumed under the verb movement parameter and the null subject parameter by English native speakers enrolled in college French. (Author/VWL)
Morge, Shelby P.
This article highlights a series of activities designed to elicit students' mathematics-related beliefs, particularly those related to gender. As a result of the activities, females in upper-level classes rated themselves as having less confidence than males, and viewing a movie clip was sufficient for some students to modify their descriptions of…
Bitter-Rijpkema, Marlies; Martens, Rob; Jochems, Wim
Tools to support knowledge elicitation are used more and more in situations where employees or students collaborate using the computer. Studies indicate that differences exist between experts and novices regarding their methods of work and reasoning. However, the commonly preferred approach tends to deal with team members as a single system with…
Sleep, Laurie; Boerst, Timothy A.
This study investigated how teacher education assignments can be designed to support beginning teachers in learning to do the work of teaching. We examined beginners' formative assessment practices--in particular, their eliciting and interpreting of students' mathematical thinking--in the context of an elementary mathematics methods assignment,…
A case study illustrates how art therapy was used to elicit the narrative of an adolescent male student in transition from incarceration to a transfer school setting. Childhood trauma was addressed in individual sessions and within a literacy group co-led by a reading specialist. The art therapist responded to the client's needs by broadening the…
Retalis, Symeon; Georgiakakis, Petros; Dimitriadis, Yannis
Design pattern creation, especially in the e-learning domain, is a highly complex process that has not been sufficiently studied and formalized. In this paper, we propose a systematic pattern development cycle, whose most important aspects focus on reverse engineering of existing systems in order to elicit features that are cross-validated through…
Hengst, Julie A.; Duff, Melissa C.
This article presents the development and piloting of a mediated discourse elicitation protocol. Grounded in situated theories of communication and informed by mediated discourse analysis, this protocol selectively samples familiar discourse types in a manner designed to preserve interactional aspects of communication. Critically, the mediated…
McDonough, Kim; Trofimovich, Pavel; Neumann, Heike
This study focuses on the pedagogical applications of structural priming research in an English for academic purposes (EAP) context, investigating whether priming activities are an effective tool for eliciting production of target grammatical structures. University students across four EAP classes carried out a total of 6 information-exchange…
Sugimoto, Sayaka; Nittono, Hiroshi; Hori, Tadao
To examine whether brain electrical responses to environmental stimuli were influenced by emotional contexts, event-related potentials (ERPs) elicited by nonstartle probe tones were recorded from 13 student volunteers while they were viewing emotionally positive, neutral, and negative slides of the International Affective Picture System. The auditory stimuli consisted of high-deviant (2000 Hz, p=.08), low-deviant (1050 Hz, p=.08), and standard (1000 Hz, p=.84) tones with a mean onset-to-onset interval of 600 ms. Participants were told to ignore the tones. High-deviant tones elicited a larger N1 (peaking around 100 ms) when participants were viewing negative slides than when viewing positive slides. The amplitude of the P2 elicited by standard tones (peaking around 170 ms) was smaller when participants were viewing positive slides than when viewing negative and neutral slides. The amplitude of the mismatch negativity (150-200 ms) tended to reduce during positive slide presentation, but this difference appeared to be due to reduction of the P2 elicited by standard tones. These findings suggest that visually induced emotional states have a sequential effect on auditory information processing, in that the influence of negative emotion appears at an earlier stage than that of positive emotion.
Smith, C. Zoe; Woodward, Anne-Marie
Describes a research assignment (called "photo-elicitation") in a graduate course on the role of photography in society in which students interview people similar to the subjects in the photographs to discover how the photographs affect them. Includes material from one research project interviewing three recovering drug addicts responding to Larry…
Bird, Steven; Lee, Haejoong
Investigating a tone language involves careful transcription of tone on words and phrases. This is challenging when the phonological categories--the tones or melodies--have not been identified. Effects such as coarticulation, sandhi, and phrase-level prosody appear as obstacles to early elicitation and classification of tone. This article presents…
Yankelewitz, Dina; Mueller, Mary; Maher, Carolyn A.
This paper reports on the forms of reasoning elicited as fourth grade students in a suburban district and sixth grade students in an urban district worked on similar tasks involving reasoning with the use of Cuisenaire rods. Analysis of the two data sets shows similarities in the reasoning used by both groups of students on specific tasks, and the…
Schadow, Jeanette; Lenz, Daniel; Thaerig, Stefanie; Busch, Niko A; Fründ, Ingo; Rieger, Jochem W; Herrmann, Christoph S
We studied the effect of different contrast levels on the visual evoked gamma-band response (GBR) in order to investigate whether the GBR is modulated in a similar manner as previously reported for visual evoked potentials. Previous studies showed that the GBR can be modulated by individual characteristics (age) and experimental conditions (task difficulty, attention). However, stimulus properties, such as size and spatial frequency, also have a large impact on the GBR, which necessitates identification and control of relevant stimulus properties for optimal experimental setups. Twenty-one healthy participants were investigated during a forced-choice discrimination task. Sinusoidal gratings were presented at three contrast levels with a constant spatial frequency of 5 cycles per degree visual arc (cpd). The present data replicate the results reported for visual evoked potentials and exhibit a contrast dependent modulation of the GBR. Gamma activity is increased for higher contrast levels. These results demonstrate the importance of stimulus contrast for evoked gamma activity. Thus, it appears meaningful to control the contrast of stimuli in experiments investigating the role of gamma activity in perception and information processing.
Sagdullaev, Botir T; McCall, Maureen A
The receptive field (RF) of most retinal ganglion cells (RGCs) is comprised of an excitatory center and an antagonistic surround. Interactions between these RF elements shape most of the visual responses of RGCs. To begin to investigate center-surround interactions of mouse RGCs quantitatively, we characterized their responses in an in vivo preparation to a variety of spot and full-field stimuli. When RGCs were stimulated with a spot that matched the cell's RF center diameter (optimal spot), all RGCs could be categorized as either ON- or OFF-center. In all RGCs, full-field stimulation significantly reduced both the peak and the mean firing rates evoked with an optimal spot stimulus. Full-field stimulation revealed differences in other response properties between ON- and OFF-center RGCs. With a full-field stimulus, the duration of the OFF-center RGCs response was reduced making them more transient, while the duration of the ON-center RGCs increased making them more sustained. Of most interest, full-field stimulation altered the RF center response sign in approximately half of the OFF-center RGCs, which became either OFF/ON or ON only. In contrast, all ON-center and the other OFF-center cells conserved their RF response sign in the presence of the full-field stimulus. We propose that sign-altering OFF-center RGCs possess an additional RF surround mechanism that underlies this alteration in their response. Of general interest these results suggest that the sole use of full-field stimulation to categorize visual response properties of RGCs does not adequately reflect their RF organization and, therefore, is not an optimal strategy for their classification.
Martens, Marijn B; Houweling, Arthur R; E Tiesinga, Paul H
Neuronal circuits in the rodent barrel cortex are characterized by stable low firing rates. However, recent experiments show that short spike trains elicited by electrical stimulation in single neurons can induce behavioral responses. Hence, the underlying neural networks provide stability against internal fluctuations in the firing rate, while simultaneously making the circuits sensitive to small external perturbations. Here we studied whether stability and sensitivity are affected by the connectivity structure in recurrently connected spiking networks. We found that anti-correlation between the number of afferent (in-degree) and efferent (out-degree) synaptic connections of neurons increases stability against pathological bursting, relative to networks where the degrees were either positively correlated or uncorrelated. In the stable network state, stimulation of a few cells could lead to a detectable change in the firing rate. To quantify the ability of networks to detect the stimulation, we used a receiver operating characteristic (ROC) analysis. For a given level of background noise, networks with anti-correlated degrees displayed the lowest false positive rates, and consequently had the highest stimulus detection performance. We propose that anti-correlation in the degree distribution may be a computational strategy employed by sensory cortices to increase the detectability of external stimuli. We show that networks with anti-correlated degrees can in principle be formed by applying learning rules comprised of a combination of spike-timing dependent plasticity, homeostatic plasticity and pruning to networks with uncorrelated degrees. To test our prediction we suggest a novel experimental method to estimate correlations in the degree distribution.
Carlsen, Anthony N; Almeida, Quincy J; Franks, Ian M
Delays in the initiation of a movement response and slowness during movement are among the hallmark motor symptoms in patients with Parkinson's disease (PD). These impairments may result from deficits in neural structures related to perception, response programming, response initiation, or a combination of all three. However, the relative impact of each process on movement control in PD is still unclear. The present study investigated which processes might be responsible for the observed slowness. Patients performed a simple reaction time (RT) task involving arm extension where the normal 82 dB acoustic "go" signal was unexpectedly replaced with a 124 dB startling acoustic stimulus (SAS) on selected trials. The SAS was used as a probe of motor preparatory state since it has been shown to act as a subcortically-mediated involuntarily trigger for actions that are sufficiently prepared and waiting to be initiated by normal cortical processes. It was expected that release of the voluntary response by startle would not occur in PD patients if bradykinetic symptoms were attributable primarily to motor programming deficits. In contrast, results clearly showed that when a SAS was presented, the prepared response was elicited at a significantly shorter latency. In addition, the amplitude and timing pattern of EMG output appeared to be improved compared to control, resulting in a faster, more normalized movement. These results suggest that in PD patients motor programming processes are relatively intact, while the dysfunctional basal ganglia likely assert an inhibitory effect on the thalamo-cortical connections responsible for the initiation of motor acts.
Background Manipulating task difficulty is a useful way of elucidating the functional recruitment of the brain’s executive control network. In a Stroop task, pre-exposing the irrelevant word using varying stimulus onset asynchronies (‘negative’ SOAs) modulates the amount of behavioural interference and facilitation, suggesting disparate mechanisms of cognitive processing in each SOA. The current study employed a Stroop task with three SOAs (−400, -200, 0 ms), using functional magnetic resonance imaging to investigate for the first time the neural effects of SOA manipulation. Of specific interest were 1) how SOA affects the neural representation of interference and facilitation; 2) response priming effects in negative SOAs; and 3) attentional effects of blocked SOA presentation. Results The results revealed three regions of the executive control network that were sensitive to SOA during Stroop interference; the 0 ms SOA elicited the greatest activation of these areas but experienced relatively smaller behavioural interference, suggesting that the enhanced recruitment led to more efficient conflict processing. Response priming effects were localized to the right inferior frontal gyrus, which is consistent with the idea that this region performed response inhibition in incongruent conditions to overcome the incorrectly-primed response, as well as more general action updating and response preparation. Finally, the right superior parietal lobe was sensitive to blocked SOA presentation and was most active for the 0 ms SOA, suggesting that this region is involved in attentional control. Conclusions SOA exerted both trial-specific and block-wide effects on executive processing, providing a unique paradigm for functional investigations of the cognitive control network. PMID:23902451
SanMiguel, Iria; Saupe, Katja; Schröger, Erich
In the present study we investigated the neural code of sensory predictions. Grounded on a variety of empirical findings, we set out from the proposal that sensory predictions are coded via the top-down modulation of the sensory units whose response properties match the specific characteristics of the predicted stimulus (Albright, 2012; Arnal and Giraud, 2012). From this proposal, we derive the hypothesis that when the specific physical characteristics of the predicted stimulus cannot be advanced, the sensory system should not be able to formulate such predictions, as it would lack the means to represent them. In different conditions, participant's self-paced button presses predicted either only the precise time when a random sound would be presented (random sound condition) or both the timing and the identity of the sound (single sound condition). To isolate prediction-related activity, we inspected the event-related potential (ERP) elicited by rare omissions of the sounds following the button press (see SanMiguel et al., 2013). As expected, in the single sound condition, omissions elicited a complex response in the ERP, reflecting the presence of sound prediction and the violation of this prediction. In contrast, in the random sound condition, sound omissions were not followed by any significant responses in the ERP. These results confirmed our hypothesis, and provide support to current proposals advocating that sensory systems rely on the top-down modulation of stimulus-specific sensory representations as the neural code for prediction. In light of these findings, we discuss the significance of the omission ERP as an electrophysiological marker of predictive processing and we address the paradox that no indicators of violations of temporal prediction alone were found in the present paradigm. PMID:23908618
van Pelt, Stan; Fries, Pascal
The peak frequency of neuronal gamma-band synchronization has received much attention in recent years. Gamma peak frequency shifts to higher frequency values for higher contrast, faster moving, and attended stimuli. In monkey V1, gamma peak frequency for a drifting grating is higher for a parafoveal as compared to an eccentric stimulus (Lima et al., 2010). This effect might be due to the cortical magnification factor: the higher cortical magnification for parafoveal stimuli increases the velocity with which the cortical representations of the moving grating stripes move across the cortical surface. Since faster moving stimuli lead to higher gamma frequency, a faster moving cortical representation might do the same. This explanation predicts that the eccentricity effect on gamma peak frequency is absent for stationary stimuli. To test this, we investigated the effect of eccentricity on gamma peak frequency by recording magnetoencephalography in human subjects while they viewed moving or stationary gratings. We found that both the moving and the stationary stimuli induced lower peak frequencies for larger eccentricities, arguing against an explanation based on the cortical magnification factor. We further investigated whether this eccentricity effect was explained by differences in the size or the spatial frequency of the expected cortical activation. Neither of those explained the eccentricity effect. We propose that the different stimulus and top-down factors leading to higher gamma peak frequency all result in higher stimulus salience, that salience is translated into gamma peak frequency, and that gamma peak frequency might subserve the preferential processing of neuronal activity induced by salient stimuli.
Bourjaily, Mark A; Miller, Paul
Animals must often make opposing responses to similar complex stimuli. Multiple sensory inputs from such stimuli combine to produce stimulus-specific patterns of neural activity. It is the differences between these activity patterns, even when small, that provide the basis for any differences in behavioral response. In the present study, we investigate three tasks with differing degrees of overlap in the inputs, each with just two response possibilities. We simulate behavioral output via winner-takes-all activity in one of two pools of neurons forming a biologically based decision-making layer. The decision-making layer receives inputs either in a direct stimulus-dependent manner or via an intervening recurrent network of neurons that form the associative layer, whose activity helps distinguish the stimuli of each task. We show that synaptic facilitation of synapses to the decision-making layer improves performance in these tasks, robustly increasing accuracy and speed of responses across multiple configurations of network inputs. Conversely, we find that synaptic depression worsens performance. In a linearly nonseparable task with exclusive-or logic, the benefit of synaptic facilitation lies in its superlinear transmission: effective synaptic strength increases with presynaptic firing rate, which enhances the already present superlinearity of presynaptic firing rate as a function of stimulus-dependent input. In linearly separable single-stimulus discrimination tasks, we find that facilitating synapses are always beneficial because synaptic facilitation always enhances any differences between inputs. Thus we predict that for optimal decision-making accuracy and speed, synapses from sensory or associative areas to decision-making or premotor areas should be facilitating.
Gill, Patrick; Woolley, Sarah M N; Fremouw, Thane; Theunissen, Frédéric E
High-level sensory neurons encoding natural stimuli are not well described by linear models operating on the time-varying stimulus intensity. Here we show that firing rates of neurons in a secondary sensory forebrain area can be better modeled by linear functions of how surprising the stimulus is. We modeled auditory neurons in the caudal lateral mesopallium (CLM) of adult male zebra finches under urethane anesthesia with linear filters convolved not with stimulus intensity, but with stimulus surprise. Surprise was quantified as the logarithm of the probability of the stimulus given the local recent stimulus history and expectations based on conspecific song. Using our surprise method, the predictions of neural responses to conspecific song improved by 67% relative to those obtained using stimulus intensity. Similar prediction improvements cannot be replicated by assuming CLM performs derivative detection. The explanatory power of surprise increased from the midbrain through the primary forebrain and to CLM. When the stimulus presented was a random synthetic ripple noise, CLM neurons (but not neurons in lower auditory areas) were best described as if they were expecting conspecific song, finding the inconsistencies between birdsong and noise surprising. In summary, spikes in CLM neurons indicate stimulus surprise more than they indicate stimulus intensity features. The concept of stimulus surprise may be useful for modeling neural responses in other higher-order sensory areas whose functions have been poorly understood.
Jacobs, Christianne; Goebel, Rainer; Sack, Alexander T
Transcranial magnetic stimulation (TMS) has established the functional relevance of early visual cortex (EVC) for visual awareness with great temporal specificity non-invasively in conscious human volunteers. Many studies have found a suppressive effect when TMS was applied over EVC 80-100 ms after the onset of the visual stimulus (post-stimulus TMS time window). Yet, few studies found task performance to also suffer when TMS was applied even before visual stimulus presentation (pre-stimulus TMS time window). This pre-stimulus TMS effect, however, remains controversially debated and its origin had mainly been ascribed to TMS-induced eye-blinking artifacts. Here, we applied chronometric TMS over EVC during the execution of a visual discrimination task, covering an exhaustive range of visual stimulus-locked TMS time windows ranging from -80 pre-stimulus to 300 ms post-stimulus onset. Electrooculographical (EoG) recordings, sham TMS stimulation, and vertex TMS stimulation controlled for different types of non-neural TMS effects. Our findings clearly reveal TMS-induced masking effects for both pre- and post-stimulus time windows, and for both objective visual discrimination performance and subjective visibility. Importantly, all effects proved to be still present after post hoc removal of eye blink trials, suggesting a neural origin for the pre-stimulus TMS suppression effect on visual awareness. We speculate based on our data that TMS exerts its pre-stimulus effect via generation of a neural state which interacts with subsequent visual input.
Rhea, Christopher K; Kiefer, Adam W; Wittstein, Matthew W; Leonard, Kelsey B; MacPherson, Ryan P; Wright, W Geoffrey; Haran, F Jay
Previous work has shown that fractal patterns in gait can be altered by entraining to a fractal stimulus. However, little is understood about how long those patterns are retained or which factors may influence stronger entrainment or retention. In experiment one, participants walked on a treadmill for 45 continuous minutes, which was separated into three phases. The first 15 minutes (pre-synchronization phase) consisted of walking without a fractal stimulus, the second 15 minutes consisted of walking while entraining to a fractal visual stimulus (synchronization phase), and the last 15 minutes (post-synchronization phase) consisted of walking without the stimulus to determine if the patterns adopted from the stimulus were retained. Fractal gait patterns were strengthened during the synchronization phase and were retained in the post-synchronization phase. In experiment two, similar methods were used to compare a continuous fractal stimulus to a discrete fractal stimulus to determine which stimulus type led to more persistent fractal gait patterns in the synchronization and post-synchronization (i.e., retention) phases. Both stimulus types led to equally persistent patterns in the synchronization phase, but only the discrete fractal stimulus led to retention of the patterns. The results add to the growing body of literature showing that fractal gait patterns can be manipulated in a predictable manner. Further, our results add to the literature by showing that the newly adopted gait patterns are retained for up to 15 minutes after entrainment and showed that a discrete visual stimulus is a better method to influence retention.
Coelho, Cesar A.O.; Dunsmoor, Joseph E.
Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design (“deepened extinction”) shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Recovery of conditioned skin conductance responses to CSA was reduced 24 h after compound extinction, as compared with a group who received an equal number of extinction trials to the CSA alone. PMID:26572649
Toeplitz ma- trix, φsr 2RL1 is the cross- covariance between the in- put and the output, and a2R is a scaling factor . The scaling factor is a result...of the stimulus is p(s) N (0;σ2s I), com- pleting the numerator of Equation 3. The denomina- tor is simply a scaling term, and can be obtained from...5 0 5 10 re ve rs e fi lt er e st im at e Results from reverse filter and MAP estimator for static Wiener sys- tem. The left two panels show the
Coelho, Cesar A O; Dunsmoor, Joseph E; Phelps, Elizabeth A
Fear-related behaviors are prone to relapse following extinction. We tested in humans a compound extinction design ("deepened extinction") shown in animal studies to reduce post-extinction fear recovery. Adult subjects underwent fear conditioning to a visual and an auditory conditioned stimulus (CSA and CSB, respectively) separately paired with an electric shock. The target CS (CSA) was extinguished alone followed by compound presentations of the extinguished CSA and nonextinguished CSB. Recovery of conditioned skin conductance responses to CSA was reduced 24 h after compound extinction, as compared with a group who received an equal number of extinction trials to the CSA alone.
Siedlecka, Marta; Klimza, Anna; Łukowska, Marta; Wierzchoń, Michał
There is a growing interest in body-ownership disruptions and their consequences for subjective experiences such as tactile sensations or pain. Here, we investigated the effect of the rubber hand illusion (RHI) on the perceived discomfort caused by cold stimulus applied to the real hand. The results showed reduced discomfort to cold reflected in behavioural and subjective measures. The stronger the illusion, the later the cold temperature became unpleasant and the less intense the experience was rated. We discuss the link between thermoception and body ownership as well as possible theoretical and methodological implications for studies on pain experience under RHI. PMID:25295527
Hirakawa, N; Tershner, S A; Fields, H L; Manning, B H
The rostral ventromedial medulla contains three physiologically defined classes of pain-modulating neuron that project to the spinal and trigeminal dorsal horns. OFF cells contribute to anti-nociceptive processes, ON cells contribute to pro-nociceptive processes (i.e. hyperalgesia) and neutral cells tonically modulate spinal nociceptive responsiveness. In the setting of noxious peripheral input, the different cell classes in this region permit bi-directional modulation of pain perception (analgesia vs hyperalgesia). It is unclear, however, whether changes in the activity of these neurons are relevant to the behaving animal in the absence of a painful stimulus. Here, we pharmacologically manipulated neurons in the rostral ventromedial medulla and used the place-conditioning paradigm to assess changes in the affective state of the animal. Local microinjection of the alpha(1)-adrenoceptor agonist methoxamine (50.0 microg in 0.5 microl; to activate ON cells, primarily), combined with local microinjection of the kappa-opioid receptor agonist U69,593 (0.178 microg in 0.5 microl; to inhibit OFF cells), produced an increase in spinal nociceptive reactivity (i.e. hyperalgesia on the tail flick assay) and a negative affective state (as inferred from the production of conditioned place avoidance) in the conscious, freely moving rat. Additional microinjection experiments using various concentrations of methoxamine alone or U69, 593 alone revealed that the rostral ventromedial medulla is capable of eliciting a range of affective changes resulting in conditioned place avoidance, no place-conditioning effect or conditioned place preference (reflecting production of a positive affective state). Overall, however, there was no consistent relationship between place-conditioning effects and changes in spinal nociceptive reactivity. This is the first report of bi-directional changes in affective state (i.e. reward or aversion production) associated with pharmacological manipulation of
Ramón, Fidel; Gronenberg, Wulfila
In vertebrates, and in humans in particular, so-called 'omitted stimulus potentials' can be electrically recorded from the brain or scalp upon repeated stimulation with simple stimuli such as light flashes. While standard evoked potentials follow each stimulus in a series, 'omitted stimulus potentials' occur when an additional stimulus is expected after the end of a stimulus series. These potentials represent neuronal plasticity and are assumed to be involved in basic cognitive processes. We recorded electroretinograms from the eyes and visually evoked potentials from central brain areas of honey bees and ants, social insects to which cognitive abilities have been ascribed and whose rich-behavioral repertoires include navigation, learning and memory. We demonstrate that omitted stimulus potentials occur in these insects. Omitted stimulus potentials in bees and ants show similar temporal characteristics to those found in crayfish and vertebrates, suggesting that common mechanisms may underlie this form of short-term neuronal plasticity.
Awan, Shaheen N.; Novaleski, Carolyn K.; Rousseau, Bernard
Objectives/Hypothesis The purpose of this study was to use nonlinear dynamic analysis methods such as phase space portraits and correlation dimension (D2) as well as descriptive spectrographic analyses to characterize acoustic signals produced during evoked rabbit phonation. Methods Seventeen New Zealand white breeder rabbits were used to perform the study. A Grass S-88 stimulator (SA Instrumentation, Encinitas, CA) and constant current isolation unit (Grass Telefactor, model PSIU6; West Warwick, RI) were used to provide electrical stimulation to laryngeal musculature, and transglottal airflow rate and stimulation current (mA) were manipulated to elicit modal, raised intensity, and pressed phonations. Central 1 second portions of the most stable portion of the acoustic waveform for modal, raised intensity, and pressed phonations were edited, and then analyzed via phase space portraits, Poincaré sections, and the estimation of the correlation dimension (D2). In an attempt to limit the effects of the highly variable and nonstationary characteristics of some of the signals being analyzed, D2 analysis was also performed on the most stable central 200 ms portion of the acoustic waveform. Descriptive analysis of each phonation was also conducted using sound spectrograms. Results Results showed that the complexity of phonation and the subsequent acoustic waveform is increased as transglottal airflow rate and degree of glottal adduction is manipulated in the evoked rabbit phonation model. In particular, phonatory complexity, as quantified via correlation dimension analyses and demonstrated via spectrographic characteristics, increases from “modal” (i.e., phonation elicited at just above the phonation threshold pressure) to raised intensity (phonation elicited by increasing transglottal airflow rate) to pressed (phonation elicited by increasing the stimulation current delivered to the larynx). Variations in a single dynamic dimension (airflow rate or adductory force
Xia, Christina Z.; Adjei, Stacey
Sensory systems must represent stimuli in manners dependent upon a wealth of factors, including stimulus intensity and duration. One way the brain might handle these complex functions is to assign the tasks throughout distributed nodes, each contributing to information processing. We sought to explore this important aspect of sensory network function in the mammalian olfactory system, wherein the intensity and duration of odor exposure are critical contributors to odor perception. This is a quintessential model for exploring processing schemes given the distribution of odor information by olfactory bulb mitral and tufted cells into several anatomically distinct secondary processing stages, including the piriform cortex (PCX) and olfactory tubercle (OT), whose unique contributions to odor coding are unresolved. We explored the coding of PCX and OT neuron responses to odor intensity and duration. We found that both structures similarly partake in representing descending intensities of odors by reduced recruitment and modulation of neurons. Additionally, while neurons in the OT adapt to odor exposure, they display reduced capacity to adapt to either repeated presentations of odor or a single prolonged odor presentation compared with neurons in the PCX. These results provide insights into manners whereby secondary olfactory structures may, at least in some cases, uniquely represent stimulus features. PMID:26041832
Gallant, Haley; Vo, Andrew; Seergobin, Ken N.; MacDonald, Penny A.
Dopaminergic therapy has paradoxical effects on cognition in Parkinson's disease (PD) patients, with some functions worsened and others improved. The dopamine overdose hypothesis is proposed as an explanation for these opposing effects of medication taking into account the varying levels of dopamine within different brain regions in PD. The detrimental effects of medication on cognition have been attributed to exogenous dopamine overdose in brain regions with spared dopamine levels in PD. It has been demonstrated that learning is most commonly worsened by dopaminergic medication. The current study aimed to investigate whether the medication-related learning impairment exhibited in PD patients is due to a main effect of medication by evaluating the dopamine overdose hypothesis in healthy young adults. Using a randomized, double-blind, placebo-controlled design, 40 healthy young undergraduate students completed a stimulus-response learning task. Half of the participants were treated with 0.5 mg of pramipexole, a dopamine agonist, whereas the other half were treated with a placebo. We found that stimulus-response learning was significantly impaired in participants on pramipexole relative to placebo controls. These findings are consistent with the dopamine overdose hypothesis and suggest that dopaminergic medication impairs learning independent of PD pathology. Our results have important clinical implications for conditions treated with pramipexole, particularly PD, restless leg syndrome, some forms of dystonia, and potentially depression. PMID:27594823
Kim, Hyun-Ah; Jeong, Man-Bok; Yi, Na-Young; Park, Shin-Ae; Kim, Won-Tae; Kim, Se-Eun; Chae, Je-Min; Seo, Kang-Moon
The aim of this study was to determine the most effective light intensity for flash electroretinogram (ERG) examination in conscious dogs using ERG equipment with a contact lens electrode with a built-in LED light source. ERG was performed on the bilateral eyes of ten clinically healthy Miniature Schnauzers at 6 different intensities (0.025, 0.079, 0.25, 0.79, 2.5 and 7.9 cd.s/m2) after dark adaptation for 20 min. With the increase in stimulus intensity, the most significant increase in a and b-wave amplitudes were observed at 2.5 cd.s/m2 (p<0.05). As the intensity of light was increased, the implicit times of both waves significantly decreased. Therefore, the most effective intensity of stimulus was 2.5 cd.s/m2 in the conscious Miniature Schnauzers. This suggests that this procedure would be applicable for evaluation of retinal function in conscious dogs, especially in high-risk patients.
Thurlings, Marieke E; Brouwer, Anne-Marie; Van Erp, Jan B F; Blankertz, Benjamin; Werkhoven, Peter J
Event-related potential (ERP)-based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain activity due to multisensory integration which may be of use in BCIs. We investigated the effect of visual-tactile stimulus presentation on the chain of ERP components, BCI performance (classification accuracies and bitrates) and participants' task performance (counting of targets). Ten participants were instructed to navigate a visual display by attending (spatially) to targets in sequences of either visual, tactile or visual-tactile stimuli. We observe that attending to visual-tactile (compared to either visual or tactile) stimuli results in an enhanced early ERP component (N1). This bimodal N1 may enhance BCI performance, as suggested by a nonsignificant positive trend in offline classification accuracies. A late ERP component (P300) is reduced when attending to visual-tactile compared to visual stimuli, which is consistent with the nonsignificant negative trend of participants' task performance. We discuss these findings in the light of affected spatial attention at high-level compared to low-level stimulus processing. Furthermore, we evaluate bimodal BCIs from a practical perspective and for future applications.
Grassi, Pablo R; Zaretskaya, Natalia; Bartels, Andreas
The integration of local moving elements into a unified gestalt percept has previously been linked to the posterior parietal cortex. There are two possible interpretations for the lack of involvement of other occipital regions. The first is that parietal cortex is indeed uniquely functionally specialized to perform grouping. Another possibility is that other visual regions can perform grouping as well, but that the large spatial separation of the local elements used previously exceeded their neurons' receptive field (RF) sizes, preventing their involvement. In this study we distinguished between these two alternatives. We measured whole-brain activity using fMRI in response to a bistable motion illusion that induced mutually exclusive percepts of either an illusory global Gestalt or of local elements. The stimulus was presented in two sizes, a large version known to activate IPS only, and a version sufficiently small to fit into the RFs of mid-level dorsal regions such as V5/MT. We found that none of the separately localized motion regions apart from parietal cortex showed a preference for global Gestalt perception, even for the smaller version of the stimulus. This outcome suggests that grouping-by-motion is mediated by a specialized size-invariant mechanism with parietal cortex as its anatomical substrate.
Murphy, G K
Commercial aviation in the United States developed rapidly from a nucleus of pilots who returned from World War I, barnstormed and flew primitive airmail routes, and were hired by the new commerical airlines of the 1930s. The death of U.S. Senator Bronson Cutting in a 1935 crash was an important stimulus to improved governmental regulation of civil aviation. The air traffic control system, primitive until and throughout World War II, was soon proven to be inadequate for postwar demands. The midair collision of two large airliners over the Grand Canyon in June 1956 that killed the 128 persons on board was itself a strong stimulus for serious efforts, particularly in improving air traffic control systems. This and many other difficult problems in aviation safety have been addressed in the subsequent 33 years, some with success, although it has not always been immediate, and with major accidents still occurring. Commercial air travel is safe and widely accepted, however, and there is promise for additional important advances here.
Gutschalk, Alexander; Steinmann, Iris
The auditory system is often considered to show little contralateral dominance but physiological reports on the contralateral dominance of activity evoked by monaural sound vary widely. Here, we show that part of this variation is stimulus-dependent: blood oxygen level dependent (BOLD) responses to 32 s of monaurally presented unmodulated noise (UN) showed activation in contralateral auditory cortex (AC) and deactivation in ipsilateral AC compared to nonstimulus baseline. Slow amplitude-modulated (AM) noise evoked strong contralateral activation and minimal ipsilateral activation. The contrast of AM-versus-UN was used to separate fMRI activity related to the slow amplitude modulation per se. This difference activation was bilateral although still stronger in contralateral AC. In magnetoencephalography (MEG), the response was dominated by the steady-state activity phase locked to the amplitude modulation. This MEG activity showed no consistent contralateral dominance across listeners. Subcortical BOLD activation was strongly contralateral subsequent to the superior olivary complex (SOC) and showed no significant difference between modulated and UN. An acallosal participant showed similar fMRI activation as the group, ruling transcallosal transmission an unlikely source of ipsilateral enhancement or ipsilateral deactivation. These results suggest that ascending activity subsequent to the SOC is strongly dominant contralateral to the stimulus ear. In contrast, the part of BOLD and MEG activity related to slow amplitude modulation is more bilateral and only observed in AC. Ipsilateral deactivation can potentially bias measures of contralateral BOLD dominance and should be considered in future studies.
Sun, Jiehuan; Hu, Xintao; Huang, Xiu; Liu, Yang; Li, Kaiming; Li, Xiang; Han, Junwei; Guo, Lei; Liu, Tianming; Zhang, Jing
There has been increasing interest in how the human brain responds to natural stimulus such as video watching in the neuroimaging field. Along this direction, this paper presents our effort in inferring consistent and reproducible functional interaction patterns under natural stimulus of video watching among known functional brain regions identified by task-based fMRI. Then, we applied and compared four statistical approaches, including Bayesian network modeling with searching algorithms: greedy equivalence search (GES), Peter and Clark (PC) analysis, independent multiple greedy equivalence search (IMaGES), and the commonly used Granger causality analysis (GCA), to infer consistent and reproducible functional interaction patterns among these brain regions. It is interesting that a number of reliable and consistent functional interaction patterns were identified by the GES, PC and IMaGES algorithms in different participating subjects when they watched multiple video shots of the same semantic category. These interaction patterns are meaningful given current neuroscience knowledge and are reasonably reproducible across different brains and video shots. In particular, these consistent functional interaction patterns are supported by structural connections derived from diffusion tensor imaging (DTI) data, suggesting the structural underpinnings of consistent functional interactions. Our work demonstrates that specific consistent patterns of functional interactions among relevant brain regions might reflect the brain's fundamental mechanisms of online processing and comprehension of video messages.
Halladay, Lindsay R; Zelikowsky, Moriel; Blair, Hugh T; Fanselow, Michael S
Anxiety disorders are often treated using extinction-based exposure therapy, but relapse is common and can occur as a result of reinstatement, whereby an aversive "trigger" can reinstate extinguished fear. Animal models of reinstatement commonly utilize a Pavlovian fear conditioning procedure, in which subjects are first trained to fear a conditional stimulus (CS) by pairing it with an aversive unconditional stimulus (US), and then extinguished by repeated presentations of the CS alone. Reinstatement is typically induced by exposing subjects to an aversive US after extinction, but here we show that exposure to a non-extinguished CS can reinstate conditional fear responding to an extinguished CS, a phenomenon we refer to as "conditional reinstatement" (CRI). Rats were trained to fear two CSs (light and tone) and subsequently underwent extinction training to only one CS (counterbalanced). Presenting the unextinguished CS (but not a novel cue) immediately after extinction reinstated conditional fear responding to the extinguished CS in a test session given 24 h later. These findings indicate that reinstatement of extinguished fear can be triggered by exposure to conditional as well as unconditional aversive stimuli, and this may help to explain why relapse is common following clinical extinction therapy in humans. Further study of CRI using animal models may prove useful for developing refined extinction therapies that are more resistant to reinstatement.
Thurlings, Marieke E.; Brouwer, Anne-Marie; Van Erp, Jan B. F.; Blankertz, Benjamin; Werkhoven, Peter J.
Event-related potential (ERP)-based brain-computer interfaces (BCIs) employ differences in brain responses to attended and ignored stimuli. Typically, visual stimuli are used. Tactile stimuli have recently been suggested as a gaze-independent alternative. Bimodal stimuli could evoke additional brain activity due to multisensory integration which may be of use in BCIs. We investigated the effect of visual-tactile stimulus presentation on the chain of ERP components, BCI performance (classification accuracies and bitrates) and participants’ task performance (counting of targets). Ten participants were instructed to navigate a visual display by attending (spatially) to targets in sequences of either visual, tactile or visual-tactile stimuli. We observe that attending to visual-tactile (compared to either visual or tactile) stimuli results in an enhanced early ERP component (N1). This bimodal N1 may enhance BCI performance, as suggested by a nonsignificant positive trend in offline classification accuracies. A late ERP component (P300) is reduced when attending to visual-tactile compared to visual stimuli, which is consistent with the nonsignificant negative trend of participants’ task performance. We discuss these findings in the light of affected spatial attention at high-level compared to low-level stimulus processing. Furthermore, we evaluate bimodal BCIs from a practical perspective and for future applications.
Bankó, Éva M; Körtvélyes, Judit; Weiss, Béla; Vidnyánszky, Zoltán
Adding noise to a visual image makes object recognition more effortful and has a widespread effect on human electrophysiological responses. However, visual cortical processes directly involved in handling the stimulus noise have yet to be identified and dissociated from the modulation of the neural responses due to the deteriorated structural information and increased stimulus uncertainty in the case of noisy images. Here we show that the impairment of face gender categorization performance in the case of noisy images in amblyopic patients correlates with amblyopic deficits measured in the noise-induced modulation of the P1/P2 components of single-trial event-related potentials (ERP). On the other hand, the N170 ERP component is similarly affected by the presence of noise in the two eyes and its modulation does not predict the behavioral deficit. These results have revealed that the efficient processing of noisy images depends on the engagement of additional processing resources both at the early, feature-specific as well as later, object-level stages of visual cortical processing reflected in the P1 and P2 ERP components, respectively. Our findings also suggest that noise-induced modulation of the N170 component might reflect diminished face-selective neuronal responses to face images with deteriorated structural information.
Woods, V M; Triantis, I F; Toumazou, C
Functional electrical stimulation with cuff electrodes involves the controlled injection of current into an electrically excitable tissue for sensory or motor rehabilitation. Some charge injected during stimulation is 'lost' at the electrode-electrolyte interface when the charge carrier is translated from an electron to an ion in the solution. The process of charge injection through chemical reactions can reduce electrode longevity and implant biocompatibility. Conventionally, the excess charge is minimized by complex hardware solutions, which are often not appropriate for robust long-term implantable solutions. Here, we present a method of waveform design that minimizes irrecoverable charge during continuous pulsing through the use of biphasic waveforms with unequally charged phases. We developed an equivalent electrical model of the electrode-electrolyte impedance based on the electrode's surface chemistry during psuedo-bipolar stimulation conditions. Simulations with the equivalent circuit determined the uncompensated charge to be a function of stimulus parameters. In vitro stimulation experiments in saline confirmed that we could preemptively compensate for the excess charge following biphasic stimulus waveforms. As a result, there was a 92% reduction in the pre-pulse potential after a pulse train with this new waveform design when compared to stimulation with conventional biphasic waveforms.
Ho, J J David; Wang, Miling; Audas, Timothy E; Kwon, Deukwoo; Carlsson, Steven K; Timpano, Sara; Evagelou, Sonia L; Brothers, Shaun; Gonzalgo, Mark L; Krieger, Jonathan R; Chen, Steven; Uniacke, James; Lee, Stephen
Protein concentrations evolve under greater evolutionary constraint than mRNA levels. Translation efficiency of mRNA represents the chief determinant of basal protein concentrations. This raises a fundamental question of how mRNA and protein levels are coordinated in dynamic systems responding to physiological stimuli. This report examines the contributions of mRNA abundance and translation efficiency to protein output in cells responding to oxygen stimulus. We show that changes in translation efficiencies, and not mRNA levels, represent the major mechanism governing cellular responses to [O2] perturbations. Two distinct cap-dependent protein synthesis machineries select mRNAs for translation: the normoxic eIF4F and the hypoxic eIF4F(H). O2-dependent remodeling of translation efficiencies enables cells to produce adaptive translatomes from preexisting mRNA pools. Differences in mRNA expression observed under different [O2] are likely neutral, given that they occur during evolution. We propose that mRNAs contain translation efficiency determinants for their triage by the translation apparatus on [O2] stimulus.
Dewey, James B.; Dhar, Sumitrajit
Behavioral pure-tone hearing thresholds and stimulus-frequency otoacoustic emissions (SFOAEs) were measured with a high frequency resolution from 0.5-20 kHz in 15 female participants. Stimuli were calibrated in terms of forward pressure level (FPL). SFOAE responses to 36 dB FPL probes were largest near 1 kHz and declined above 8-10 kHz, though were still measurable at frequencies approaching 16 kHz in some ears. SFOAEs typically dropped in amplitude at a frequency that was roughly one octave below the "corner" frequency of the audiogram, and one-third to one-half of an octave below the frequency where thresholds departed from highly sensitive hearing. High-frequency SFOAE responses are likely limited by a reduction in the efficiency of the underlying generation mechanism and/or a diminished region of generation as the stimulus-driven excitation approaches the basal-most portion of the cochlea.
Chung, Susana T. L.
Objects that are briefly flashed around the time of saccades are mislocalized. Previously, robust interactions between saccadic perceptual distortions and stimulus contrast have been reported. It is also known that crowding depends on the contrast of the target and flankers. Here, we investigated how stimulus contrast and crowding interact with pre-saccadic perception. We asked observers to report the orientation of a tilted Gabor presented in the periphery, with or without four flanking vertically oriented Gabors. Observers performed the task either following a saccade or while maintaining fixation. Contrasts of the target and flankers were independently set to either high or low, with equal probability. In both the fixation and saccade conditions, the flanked conditions resulted in worse discrimination performance—the crowding effect. In the unflanked saccade trials, performance significantly decreased with target-to-saccade onset for low-contrast targets but not for high-contrast targets. In the presence of flankers, impending saccades reduced performance only for low-contrast, but not for high-contrast flankers. Interestingly, average performance in the fixation and saccade conditions was mostly similar in all contrast conditions. Moreover, the magnitude of crowding was influenced by saccades only when the target had high contrast and the flankers had low contrasts. Overall, our results are consistent with modulation of perisaccadic spatial localization by contrast and saccadic suppression, but at odds with a recent report of pre-saccadic release of crowding. PMID:28386420
Burns, Devin M
The speeded classification tasks popularized by Garner (1974), with their accompanying labels of separable and integral dimensions, have become the dominant paradigm for characterizing perceptual interactions between stimulus dimensions. Separable dimensions like color and shape can be selectively attended to at will, but integral dimensions like hue and brightness cannot. When classifying stimuli with respect to a single dimension, integral stimuli lead to faster performance in the baseline block, where only that single dimension varies, than in the filtering block, in which a second dimension is allowed to vary irrelevantly. No such difference is predicted for separable dimensions lead to no difference. The comparison between baseline and filtering confounds a change in the number of stimuli with a change in the number of variant dimensions. A new experimental condition is proposed utilizing three stimulus dimensions to hold the number of stimuli constant while introducing variance along a second irrelevant dimension. Data indicate that interference increases, suggesting that changes in the number of potential stimuli within a block are not necessary for Garner interference, in contrast to the accounts provided by extant quantitative models.
Huang, Ruey-Song; Sereno, Martin I
Imaging the neural basis of visuomotor actions using fMRI is a topic of increasing interest in the field of cognitive neuroscience. One challenge is to present realistic three-dimensional (3-D) stimuli in the subject's peripersonal space inside the MRI scanner. The stimulus generating apparatus must be compatible with strong magnetic fields and must not interfere with image acquisition. Virtual 3-D stimuli can be generated with a stereo image pair projected onto screens or via binocular goggles. Here, we describe designs and implementations for automatically presenting physical 3-D stimuli (point-light targets) in peripersonal and near-face space using fiber optics in the MRI scanner. The feasibility of fiber-optic based displays was demonstrated in two experiments. The first presented a point-light array along a slanted surface near the body, and the second presented multiple point-light targets around the face. Stimuli were presented using phase-encoded paradigms in both experiments. The results suggest that fiber-optic based displays can be a complementary approach for visual stimulus presentation in the MRI scanner.
Deleon, Jessica; Gesierich, Benno; Besbris, Max; Ogar, Jennifer; Henry, Maya L; Miller, Bruce L; Gorno-Tempini, Maria Luisa; Wilson, Stephen M
Many patients with primary progressive aphasia (PPA) are impaired in syntactic production. Because most previous studies of expressive syntax in PPA have relied on quantitative analysis of connected speech samples, which is a relatively unconstrained task, it is not well understood which specific syntactic structures are most challenging for these patients. We used an elicited syntactic production task to identify which syntactic structures pose difficulties for 31 patients with three variants of PPA: non-fluent/agrammatic, semantic and logopenic. Neurodegenerative and healthy age-matched participants were included as controls. As expected, non-fluent/agrammatic patients made the most syntactic errors. The structures that resulted in the most errors were constructions involving third person singular present agreement, and constructions involving embedded clauses. Deficits on this elicited production task were associated with atrophy of the left posterior inferior frontal gyrus.
Bebbington, Mark; Stirling, Mark; Cronin, Shane; Wang, Ting; Jolly, Gill
The quantification of volcanic hazard at national level is a vital pre-requisite to placing volcanic risk on a platform that permits meaningful comparison with other hazards such as earthquakes. New Zealand has up to a dozen dangerous volcanoes, with the usual mixed degrees of knowledge concerning their temporal and spatial eruptive history. Information on the 'size' of the eruptions, be it in terms of VEI, volume or duration, is sketchy at best. These limitations and the need for a uniform approach lend themselves to a subjective hazard analysis via expert elicitation. Approximately 20 New Zealand volcanologists provided estimates for the size of the next eruption from each volcano and, conditional on this, its location, timing and duration. Opinions were likewise elicited from a control group of statisticians, seismologists and (geo)chemists, all of whom had at least heard the term 'volcano'. The opinions were combined via the Cooke classical method. We will report on the preliminary results from the exercise.
Ronald L. Boring; David Gertman; Jeffrey Joe; Julie Marble; William Galyean; Larry Blackwood; Harold Blackman
This report describes a simplified, tractable, and usable procedure within the US Nuclear Regulator Commission (NRC) for seeking expert opinion and judgment. The NRC has increased efforts to document the reliability and risk of nuclear power plants (NPPs) through Probabilistic Risk Assessment (PRA) and Human Reliability Analysis (HRA) models. The Significance Determination Process (SDP) and Accident Sequence Precursor (ASP) programs at the NRC utilize expert judgment on the probability of failure, human error, and the operability of equipment in cases where otherwise insufficient operational data exist to make meaningful estimates. In the past, the SDP and ASP programs informally sought the opinion of experts inside and outside the NRC. This document represents a formal, documented procedure to take the place of informal expert elicitation. The procedures outlined in this report follow existing formal expert elicitation methodologies, but are streamlined as appropriate to the degree of accuracy required and the schedule for producing SDP and ASP analyses.
Imoto, Setsuko; Ohta, Yoshimoto
Induction of stress metabolites in the suspension cultured cells of eggplant (Solanum melongena L.) was examined. When autoclaved RNase A or nigeran, both of which are nonspecific phytoalexin elicitors in bean cells, were added to the cell culture of eggplant, greatly enhanced levels of three compounds were observed. One of them was cis-pentadeca-6-ene-1,3-diyne-5,15-diol, a novel diacetylenic compound. This compound has considerable fungitoxic activity. Also identified was falcarindiol, another fungitoxic diacetylenic compound previously reported as one of the phytoalexins in infected tomato fruits and leaves. Elicited compounds preferentially accumulated in the culture medium rather than in the cells and decreased to original levels during prolonged culturing. The elicitation of these compounds was closely correlated with cellular damage in terms of the decrease of growth rate and was inhibited by 10 micromolar cycloheximide. PMID:16665862
Dowker, A D
Attempts were made to elicit poems from 133 children between the ages of 2;3 and 6;11. Seventy-eight of the children produced 606 poems between them. Forty-five per cent of the poems contained the syntactic device of modified repetition: a substitution exercise where a grammatical frame is repeated and the substitution occurs in part of the grammatical frame. This was so despite the fact that modified repetition was not present in the examples that were used to elicit poems from the children. The frequency and types of modified repetition used by the children did not vary much with age. The question of whether children's use of modified repetition in their rhythmical poems has the function of helping them to practise grammatical forms, or whether it is simply one reflection of a general human tendency towards the use of pattern in language, is discussed.
Elijah, Daniel H.; Samengo, Inés; Montemurro, Marcelo A.
Thalamic neurons have been long assumed to fire in tonic mode during perceptive states, and in burst mode during sleep and unconsciousness. However, recent evidence suggests that bursts may also be relevant in the encoding of sensory information. Here, we explore the neural code of such thalamic bursts. In order to assess whether the burst code is generic or whether it depends on the detailed properties of each bursting neuron, we analyzed two neuron models incorporating different levels of biological detail. One of the models contained no information of the biophysical processes entailed in spike generation, and described neuron activity at a phenomenological level. The second model represented the evolution of the individual ionic conductances involved in spiking and bursting, and required a large number of parameters. We analyzed the models' input selectivity using reverse correlation methods and information theory. We found that n-spike bursts from both models transmit information by modulating their spike count in response to changes to instantaneous input features, such as slope, phase, amplitude, etc. The stimulus feature that is most efficiently encoded by bursts, however, need not coincide with one of such classical features. We therefore searched for the optimal feature among all those that could be expressed as a linear transformation of the time-dependent input current. We found that bursting neurons transmitted 6 times more information about such more general features. The relevant events in the stimulus were located in a time window spanning ~100 ms before and ~20 ms after burst onset. Most importantly, the neural code employed by the simple and the biologically realistic models was largely the same, implying that the simple thalamic neuron model contains the essential ingredients that account for the computational properties of the thalamic burst code. Thus, our results suggest the n-spike burst code is a general property of thalamic neurons. PMID
Coppersmith, Kevin J.; Perman, Roseanne C.
This report presents results of the Saturated Zone Flow and Transport Expert Elicitation (SZEE) project for Yucca Mountain, Nevada. This project was sponsored by the US Department of Energy (DOE) and managed by Geomatrix Consultants, Inc. (Geomatrix), for TRW Environmental Safety Systems, Inc. The DOE's Yucca Mountain Site Characterization Project (referred to as the YMP) is intended to evaluate the suitability of the site for construction of a mined geologic repository for the permanent disposal of spent nuclear fuel and high-level radioactive waste. The SZEE project is one of several that involve the elicitation of experts to characterize the knowledge and uncertainties regarding key inputs to the Yucca Mountain Total System Performance Assessment (TSPA). The objective of the current project was to characterize the uncertainties associated with certain key issues related to the saturated zone system in the Yucca Mountain area and downgradient region. An understanding of saturated zone processes is critical to evaluating the performance of the potential high-level nuclear waste repository at Yucca Mountain. A major goal of the project was to capture the uncertainties involved in assessing the saturated flow processes, including uncertainty in both the models used to represent the physical processes controlling saturated zone flow and transport, and the parameter values used in the models. So that the analysis included a wide range of perspectives, multiple individual judgments were elicited from members of an expert panel. The panel members, who were experts from within and outside the Yucca Mountain project, represented a range of experience and expertise. A deliberate process was followed in facilitating interactions among the experts, in training them to express their uncertainties, and in eliciting their interpretations. The resulting assessments and probability distributions, therefore, provide a reasonable aggregate representation of the knowledge and
Greenberg, Marc W.
Adapt/combine known methods to demonstrate an expert judgment elicitation process that: 1.Models expert's inputs as a triangular distribution, 2.Incorporates techniques to account for expert bias and 3.Is structured in a way to help justify expert's inputs. This paper will show one way of "extracting" expert opinion for estimating purposes. Nevertheless, as with most subjective methods, there are many ways to do this.
Al-Abduljawad, K A; Baqui, F; Langley, R W; Bradshaw, C M; Szabadi, E
The acoustic startle response includes rapid muscular contractions elicited by loud sounds; it may be measured in humans as the electromyographic response of the orbicularis oculi muscle. Enhancement of this response during exposure to threat of electric shock (fear- potentiated startle) is a widely used model of human anxiety. A problem with the use of the startle reflex in studies of human anxiety is the aversiveness of startle-eliciting sounds, which may, in some subjects, exceed the aversiveness of the electric shock itself. We have recently found that the long-latency N1/P2 auditory-evoked potential elicited by loud sounds is subject to fear potentiation. However, it is not known whether N1/P2 potentials elicited by low-intensity sounds, which do not elicit the startle response, are also subject to fear potentiation. This study examined the susceptibility of the N1/P2 potential elicited by low-intensity sounds to fear potentiation, and the effect of the anxiolytic diazepam on the N1/P2 potential in the absence and presence of threat of electric shock. Fifteen male volunteers (18-43 years) participated in three sessions in which they received placebo, diazepam 5 mg and diazepam 10 mg according to a double-blind protocol. Sixty minutes after treatment, auditory-evoked potentials were elicited by 40 ms 1 kHz tones 5, 10, 15, 20 and 25 dB[A] above a background of 70 dB[A]. Recording sessions consisted of eight alternating 2 min THREAT and SAFE blocks; unpredictable shocks (1.8 mA, 50 ms) were delivered to the subject's wrist in THREAT blocks (1-4 shocks per block). The amplitude of the N1/P2 potential increased monotonically as a function of stimulus intensity. The responses were significantly greater during THREAT blocks than during SAFE blocks (fear potentiation). Diazepam attenuated the responses in both the SAFE and THREAT conditions. Fear potentiation of the N1/P2 potential was significantly reduced by diazepam. Diazepam reduced subjective alertness and
Tkačik, Gašper; Ghosh, Anandamohan; Schneidman, Elad; Segev, Ronen
Adaptation in the retina is thought to optimize the encoding of natural light signals into sequences of spikes sent to the brain. While adaptive changes in retinal processing to the variations of the mean luminance level and second-order stimulus statistics have been documented before, no such measurements have been performed when higher-order moments of the light distribution change. We therefore measured the ganglion cell responses in the tiger salamander retina to controlled changes in the second (contrast), third (skew) and fourth (kurtosis) moments of the light intensity distribution of spatially uniform temporally independent stimuli. The skew and kurtosis of the stimuli were chosen to cover the range observed in natural scenes. We quantified adaptation in ganglion cells by studying linear-nonlinear models that capture well the retinal encoding properties across all stimuli. We found that the encoding properties of retinal ganglion cells change only marginally when higher-order statistics change, compared to the changes observed in response to the variation in contrast. By analyzing optimal coding in LN-type models, we showed that neurons can maintain a high information rate without large dynamic adaptation to changes in skew or kurtosis. This is because, for uncorrelated stimuli, spatio-temporal summation within the receptive field averages away non-gaussian aspects of the light intensity distribution.
Iha, Higor A.; Kunisawa, Naofumi; Shimizu, Saki; Tokudome, Kentaro; Mukai, Takahiro; Kinboshi, Masato; Ikeda, Akio; Ito, Hidefumi; Serikawa, Tadao; Ohno, Yukihiro
Nicotinic acetylcholine (nACh) receptors are implicated in the pathogenesis of epileptic disorders; however, the mechanisms of nACh receptors in seizure generation remain unknown. Here, we performed behavioral and immunohistochemical studies in mice and rats to clarify the mechanisms underlying nicotine-induced seizures. Treatment of animals with nicotine (1–4 mg/kg, i.p.) produced motor excitement in a dose-dependent manner and elicited convulsive seizures at 3 and 4 mg/kg. The nicotine-induced seizures were abolished by a subtype non-selective nACh antagonist, mecamylamine (MEC). An α7 nACh antagonist, methyllycaconitine, also significantly inhibited nicotine-induced seizures whereas an α4β2 nACh antagonist, dihydro-β-erythroidine, affected only weakly. Topographical analysis of Fos protein expression, a biological marker of neural excitation, revealed that a convulsive dose (4 mg/kg) of nicotine region-specifically activated neurons in the piriform cortex, amygdala, medial habenula, paratenial thalamus, anterior hypothalamus and solitary nucleus among 48 brain regions examined, and this was also suppressed by MEC. In addition, electric lesioning of the amygdala, but not the piriform cortex, medial habenula and thalamus, specifically inhibited nicotine-induced seizures. Furthermore, microinjection of nicotine (100 and 300 μg/side) into the amygdala elicited convulsive seizures in a dose-related manner. The present results suggest that nicotine elicits convulsive seizures by activating amygdalar neurons mainly via α7 nACh receptors. PMID:28232801
The concept of emitted behavior was formulated as a part of the original argument for the validity of a new kind of learning called operant conditioning. The rationale for operant conditioning contrasted it with Pavlovian or classical conditioning, which was (and remains) fundamentally based on responses to conditioned and unconditioned stimuli. Classical conditioned responses were said to be elicited. In contrast, operant behavior was viewed as emitted and controlled primarily by response consequences rather than antecedents. I argue that the distinction between emitted and elicited behavior is no longer warranted for three major reasons. First, the distinction was based on a view of Pavlovian conditioning that is no longer viable. Second, the distinction is incompatible with both empirical data and contemporary conceptualizations of operant behavior. Third, the only way to overcome these problems is to define emitted and elicited in terms of the type of conditioning (operant and classical) that produces these behaviors, but that approach makes the definitions circular and does not avoid implications of the terms that are misleading and counterproductive in light of contemporary research and thinking.
Jenkins, J.A.; Klesius, P.H.
Four chemicals were evaluated for elicitation of macrophages in peritoneal cavities of 250-300g healthy channel catfish Ictalurus punctatus. Cellular exudates were collected at 3, 5, 7, 10, 14, and 20 d following intraperitoneal injections with squalene, Freund's incomplete adjuvant (FIA), goat serum, thioglycollate, or as a control, phosphate-buffered saline. Injection with either squalene or FIA induced significantly greater (P ??? 0.0001) macrophage recruitment than the other chemicals. The effectiveness of squalene and FIA was compared further by macrophage collection daily for 7 d. Squalene and FIA elicited similarly high macrophage responses (P ??? 0.0450), the highest being 3.43 x 106 macrophages/mL (SE, 2.4 x l06) at 99% purity at day 2 and 2.1 X 106 macrophages/mL (SE, 0.7 x 106) at day 14 at 80% purity, respectively. In both experiments, the time after injection was not statistically significant, nor was there an interaction between time and chemicals. The occurrence of cells other than macrophages decreased with time to yield macrophage recoveries of 47-99% for squalene and 30-80% for FIA. Two subsets of macrophages were observed by means of flow cytometry. As demonstrated by chemiluminescence, the squalene-elicited cells produced high-energy oxygen compounds important to the phagocytic process.
Fernández, Cristina; Pascual, Juan C; Soler, Joaquim; Elices, Matilde; Portella, Maria J; Fernández-Abascal, Enrique
Emotion-eliciting films are commonly used to evoke subjective emotional responses in experimental settings. The main aim of the present study was to investigate whether a set of film clips with discrete emotions were capable to elicit measurable objective physiological responses. The convergence between subjective and objective measures was evaluated. Finally, the effect of gender on emotional responses was investigated. A sample of 123 subjects participated in the study. Individuals were asked to view a set of emotional film clips capable to induce seven emotions: anger, fear, sadness, disgust, amusement, tenderness and neutral state. Skin conductance level (SCL), heart rate (HR) and subjective emotional responses were measured for each film clip. In comparison with neutral films, SCL was significantly increased after viewing fear films, and HR was also significantly incremented for anger and fear films. Physiological variations were associated with arousal measures indicating a convergence between subjective and objective reactions. Women appeared to display significantly greater SCL and HR responses for films inducing sadness. The findings suggest that physiological activation would be more easily induced by emotion-eliciting films that tap into emotions with higher subjective arousal such as anger and fear.
Gandi, Suryakala; Rao, Kiranmayee; Chodisetti, Bhuvaneswari; Giri, Archana
Andrographis paniculata belonging to the family Acanthaceae produces a group of diterpene lactones, one of which is the pharmaceutically important-andrographolide. It is known to possess various important biological properties like anticancer, anti-HIV, anti-inflammatory, etc. This is the first report on the production of andrographolide in the cell suspension cultures of Andrographis paniculata by 'elicitation'. Elicitation was attempted to enhance the andrographolide content in the suspension cultures of Andrographis paniculata and also to ascertain its stimulation under stress conditions or in response to pathogen attack. The maximum andrographolide production was found to be 1.53 mg/g dry cell weight (DCW) at the end of stationary phase during the growth curve. The biotic elicitors (yeast, Escherichia coli, Bacillus subtilis, Agrobacterium rhizogenes 532 and Agrobacterium tumefaciens C 58) were more effective in eliciting the response when compared to the abiotic elicitors (CdCl(2), AgNO(3), CuCl(2) and HgCl(2)). Yeast has shown to stimulate maximum accumulation of 13.5 mg/g DCW andrographolide, which was found to be 8.82-fold higher than the untreated cultures.
Zamorano, Francisco; Billeke, Pablo; Hurtado, José M; López, Vladimir; Carrasco, Ximena; Ossandón, Tomás; Aboitiz, Francisco
The capacity to inhibit prepotent and automatic responses is crucial for proper cognitive and social development, and inhibitory impairments have been considered to be key for some neuropsychiatric conditions. One of the most used paradigms to analyze inhibitory processes is the Go-Nogo task (GNG). This task has been widely used in psychophysical and cognitive EEG studies, and more recently in paradigms using fMRI. However, a technical limitation is that the time resolution of fMRI is poorer than that of the EEG technique. In order to compensate for these temporal constraints, it has become common practice in the fMRI field to use longer inter-stimulus intervals (ISI) than those used in EEG protocols. Despite the noticeable temporal differences between these two techniques, it is currently assumed that both approaches assess similar inhibitory processes. We performed an EEG study using a GNG task with both short ISI (fast-condition, FC, as in EEG protocols) and long ISI (slow-condition, SC, as in fMRI protocols). We found that in the FC there was a stronger Nogo-N2 effect than in the SC. Moreover, in the FC, but not in the SC, the number of preceding Go trials correlated positively with the Nogo-P3 amplitude and with the Go trial reaction time; and negatively with commission errors. In addition, we found significant topographical differences for the Go-P3 elicited in FC and SC, which is interpreted in terms of different neurotransmitter dynamics. Taken together, our results provide evidence that frequency of stimulus presentation in the GNG task strongly modulates the behavioral response and the evoked EEG activity. Therefore, it is likely that short-ISI EEG protocols and long-ISI fMRI protocols do not assess equivalent inhibitory processes.
Zamorano, Francisco; Billeke, Pablo; Hurtado, José M.; López, Vladimir; Carrasco, Ximena; Ossandón, Tomás; Aboitiz, Francisco
The capacity to inhibit prepotent and automatic responses is crucial for proper cognitive and social development, and inhibitory impairments have been considered to be key for some neuropsychiatric conditions. One of the most used paradigms to analyze inhibitory processes is the Go-Nogo task (GNG). This task has been widely used in psychophysical and cognitive EEG studies, and more recently in paradigms using fMRI. However, a technical limitation is that the time resolution of fMRI is poorer than that of the EEG technique. In order to compensate for these temporal constraints, it has become common practice in the fMRI field to use longer inter-stimulus intervals (ISI) than those used in EEG protocols. Despite the noticeable temporal differences between these two techniques, it is currently assumed that both approaches assess similar inhibitory processes. We performed an EEG study using a GNG task with both short ISI (fast-condition, FC, as in EEG protocols) and long ISI (slow-condition, SC, as in fMRI protocols). We found that in the FC there was a stronger Nogo-N2 effect than in the SC. Moreover, in the FC, but not in the SC, the number of preceding Go trials correlated positively with the Nogo-P3 amplitude and with the Go trial reaction time; and negatively with commission errors. In addition, we found significant topographical differences for the Go-P3 elicited in FC and SC, which is interpreted in terms of different neurotransmitter dynamics. Taken together, our results provide evidence that frequency of stimulus presentation in the GNG task strongly modulates the behavioral response and the evoked EEG activity. Therefore, it is likely that short-ISI EEG protocols and long-ISI fMRI protocols do not assess equivalent inhibitory processes. PMID:24489875
Licari, F. G.; Shkoukani, M.
Optical imaging with voltage-sensitive dye was used to examine the spatiotemporal dynamics of stimulus-driven activity on the surface of the dorsal cochlear nucleus (DCN). Stimulation with tones at low to moderate levels produced localized regions of activation that were most commonly elongated rostrocaudally. The size of these activation areas expanded with increases in sound level, while their centers shifted from the lateral direction to the medial direction with increases in stimulus frequency. In contrast to the tonotopic patterns of activation evoked by tones, electrical stimulation of the DCN surface resulted in bands of activation that were elongated along the medial-lateral axis; response latencies increased with distance along these bands from the point of stimulation. Shifting the site of electrical stimulation from the rostral direction to the caudal direction induced corresponding shifts in the rostrocaudal location of the activation band; moving the electrode tip to subsurface depths resulted in loss of the elongated band. Transecting the DCN along the rostrocaudal axis midway between its medial and lateral extremities blocked propagation of the response to the half of the DCN distal to but not proximal to the stimulating electrode. The results suggest that the two modes of stimulation activated two distinct populations of neurons, one involving primarily tonotopically organized cells and the other crossing these tonotopic zones and likely representing the activation of parallel fibers. These results reveal a number of new features in the spatial patterns of tone-elicited activation that are not readily predicted by responses recorded electrophysiologically. PMID:21543759
Heath, Matthew; Gillen, Caitlin; Samani, Ashna
Antisaccades are a nonstandard task requiring a response mirror-symmetrical to the location of a target. The completion of an antisaccade has been shown to delay the reaction time (RT) of a subsequent prosaccade, whereas the converse switch elicits a null RT cost (i.e., the unidirectional prosaccade switch-cost). The present study sought to determine whether the prosaccade switch-cost arises from low-level interference specific to the sensory features of a target (i.e., modality-dependent) or manifests via the high-level demands of dissociating the spatial relations between stimulus and response (i.e., modality-independent). Participants alternated between pro- and antisaccades wherein the target associated with the response alternated between visual and auditory modalities. Thus, the present design involved task-switch (i.e., switching from a pro- to antisaccade and vice versa) and modality-switch (i.e., switching from a visual to auditory target and vice versa) trials as well as their task- and modality-repetition counterparts. RTs were longer for modality-switch than modality-repetition trials. Notably, however, modality-switch trials did not nullify or lessen the unidirectional prosaccade switch-cost; that is, the magnitude of the RT cost for task-switch prosaccades was equivalent across modality-switch and modality-repetition trials. Thus, competitive interference within a sensory modality does not contribute to the unidirectional prosaccade switch-cost. Instead, the modality-independent findings evince that dissociating the spatial relations between stimulus and response instantiates a high-level and inertially persistent nonstandard task-set that impedes the planning of a subsequent prosaccade.
Quaresmini, Caterina; Forrester, Gillian S; Spiezio, Caterina; Vallortigara, Giorgio
The influence of the social environment on lateralized behaviors has now been investigated across a wide variety of animal species. New evidence suggests that the social environment can modulate behavior. Currently, there is a paucity of data relating to how primates navigate their environmental space, and investigations that consider the naturalistic context of the individual are few and fragmented. Moreover, there are competing theories about whether only the right or rather both cerebral hemispheres are involved in the processing of social stimuli, especially in emotion processing. Here we provide the first report of lateralized social behaviors elicited by great apes. We employed a continuous focal animal sampling method to record the spontaneous interactions of a captive zoo-living colony of chimpanzees (Pan troglodytes) and a biological family group of peer-reared western lowland gorillas (Gorilla gorilla gorilla). We specifically focused on which side of the body (i.e., front, rear, left, right) the focal individual preferred to keep conspecifics. Utilizing a newly developed quantitative corpus-coding scheme, analysis revealed both chimpanzees and gorillas demonstrated a significant group-level preference for focal individuals to keep conspecifics positioned to the front of them compared with behind them. More interestingly, both groups also manifested a population-level bias to keep conspecifics on their left side compared with their right side. Our findings suggest a social processing dominance of the right hemisphere for context-specific social environments. Results are discussed in light of the evolutionary adaptive value of social stimulus as a triggering factor for the manifestation of group-level lateralized behaviors.
Thum, Jacob S.; Parsons, Gregory; Whittle, Taylor
Exercise adherence is affected by factors including perceptions of enjoyment, time availability, and intrinsic motivation. Approximately 50% of individuals withdraw from an exercise program within the first 6 mo of initiation, citing lack of time as a main influence. Time efficient exercise such as high intensity interval training (HIIT) may provide an alternative to moderate intensity continuous exercise (MICT) to elicit substantial health benefits. This study examined differences in enjoyment, affect, and perceived exertion between MICT and HIIT. Twelve recreationally active men and women (age = 29.5 ± 10.7 yr, VO2max = 41.4 ± 4.1 mL/kg/min, BMI = 23.1 ± 2.1 kg/m2) initially performed a VO2max test on a cycle ergometer to determine appropriate workloads for subsequent exercise bouts. Each subject returned for two additional exercise trials, performing either HIIT (eight 1 min bouts of cycling at 85% maximal workload (Wmax) with 1 min of active recovery between bouts) or MICT (20 min of cycling at 45% Wmax) in randomized order. During exercise, rating of perceived exertion (RPE), affect, and blood lactate concentration (BLa) were measured. Additionally, the Physical Activity Enjoyment Scale (PACES) was completed after exercise. Results showed higher enjoyment (p = 0.013) in response to HIIT (103.8 ± 9.4) versus MICT (84.2 ± 19.1). Eleven of 12 participants (92%) preferred HIIT to MICT. However, affect was lower (p<0.05) and HR, RPE, and BLa were higher (p<0.05) in HIIT versus MICT. Although HIIT is more physically demanding than MICT, individuals report greater enjoyment due to its time efficiency and constantly changing stimulus. Trial Registration: NCT:02981667. PMID:28076352
Thum, Jacob S; Parsons, Gregory; Whittle, Taylor; Astorino, Todd A
Exercise adherence is affected by factors including perceptions of enjoyment, time availability, and intrinsic motivation. Approximately 50% of individuals withdraw from an exercise program within the first 6 mo of initiation, citing lack of time as a main influence. Time efficient exercise such as high intensity interval training (HIIT) may provide an alternative to moderate intensity continuous exercise (MICT) to elicit substantial health benefits. This study examined differences in enjoyment, affect, and perceived exertion between MICT and HIIT. Twelve recreationally active men and women (age = 29.5 ± 10.7 yr, VO2max = 41.4 ± 4.1 mL/kg/min, BMI = 23.1 ± 2.1 kg/m2) initially performed a VO2max test on a cycle ergometer to determine appropriate workloads for subsequent exercise bouts. Each subject returned for two additional exercise trials, performing either HIIT (eight 1 min bouts of cycling at 85% maximal workload (Wmax) with 1 min of active recovery between bouts) or MICT (20 min of cycling at 45% Wmax) in randomized order. During exercise, rating of perceived exertion (RPE), affect, and blood lactate concentration (BLa) were measured. Additionally, the Physical Activity Enjoyment Scale (PACES) was completed after exercise. Results showed higher enjoyment (p = 0.013) in response to HIIT (103.8 ± 9.4) versus MICT (84.2 ± 19.1). Eleven of 12 participants (92%) preferred HIIT to MICT. However, affect was lower (p<0.05) and HR, RPE, and BLa were higher (p<0.05) in HIIT versus MICT. Although HIIT is more physically demanding than MICT, individuals report greater enjoyment due to its time efficiency and constantly changing stimulus.
A Multi-Agent Alphavirus DNA Vaccine Delivered by Intramuscular Electroporation Elicits Robust and Durable Virus Specific Immune Responses in Mice and Rabbits and Completely Protects Mice against Lethal Venezuelan, Western, and Eastern Equine Encephalitis Virus Aerosol Challenges
A Multi-Agent Alphavirus DNA Vaccine Delivered by Intramuscular Electroporation Elicits 1 Robust and Durable Virus-Specific Immune Responses in Mice...Agent Alphavirus DNA Vaccine Protects Mice 12 13 #Address correspondence to Lesley C. Dupuy, firstname.lastname@example.org. 14 *Present address...virus (VEEV) DNA vaccine 21 that was optimized for increased antigen expression and delivered by intramuscular (IM) 22 electroporation (EP) elicits
Ellam, L D; Fieldman, G B; Garlick, J; Goldsmith, R; Pateman, C
In this investigation the physical fitness of 34 recruits to the UK Fire Service was assessed before and after their initial training (tests 1-2) and on three occasions (tests 3-5) during the first 18 months of their service (n = 34 + 6 = 40). The initial training (test 2-test 1) resulted in an increase in maximum aerobic power (11% p < 0.05), body mass (2 kg, p < 0.001), lean body mass (2.02 kg, p < 0.001), grip and lifting strengths (p < 0.001), and in calf girth (p < 0.05). But no change in waist girth, maximum anaerobic power or measures of lung function was noted. There was evidence therefore that the men became physically fitter. In the first eighteen months of their service, subjects' maximum oxygen consumption declined to pre-training levels, while body mass continued to increase with a decrease in lean body mass (p < 0.001). Strength remained unaltered or tended to fall with a decrease in calf girth (p < 0.05). These changes reflected a return towards pre-training physical fitness levels. It is suggested that the initial training, while ill-matched to the firemen's habitual activity, produced levels of physical fitness which may approximate more closely to the infrequent peak requirements experienced by the men during actual fire fighting. Consequently it is concluded that the physical training during service was insufficiently intense and that a more effective programme could be designed to maintain an appropriate level of physical fitness.
Hermes, D; Miller, K J; Wandell, B A; Winawer, J
A striking feature of some field potential recordings in visual cortex is a rhythmic oscillation within the gamma band (30-80 Hz). These oscillations have been proposed to underlie computations in perception, attention, and information transmission. Recent studies of cortical field potentials, including human electrocorticography (ECoG), have emphasized another signal within the gamma band, a nonoscillatory, broadband signal, spanning 80-200 Hz. It remains unclear under what conditions gamma oscillations are elicited in visual cortex, whether they are necessary and ubiquitous in visual encoding, and what relationship they have to nonoscillatory, broadband field potentials. We demonstrate that ECoG responses in human visual cortex (V1/V2/V3) can include robust narrowband gamma oscillations, and that these oscillations are reliably elicited by some spatial contrast patterns (luminance gratings) but not by others (noise patterns and many natural images). The gamma oscillations can be conspicuous and robust, but because they are absent for many stimuli, which observers can see and recognize, the oscillations are not necessary for seeing. In contrast, all visual stimuli induced broadband spectral changes in ECoG responses. Asynchronous neural signals in visual cortex, reflected in the broadband ECoG response, can support transmission of information for perception and recognition in the absence of pronounced gamma oscillations.
Giesen, Carina; Rothermund, Klaus
Stimulus-response (S-R) episodes are formed whenever a response is executed in close temporal proximity to a stimulus. Subsequent stimulus repetition will retrieve the episode from memory, reactivating the previous response. Whereas many research findings attest to the flexibility of representing stimulus features, only little is known about the…
Hasshim, Nabil; Parris, Benjamin A
Conflict in the Stroop task is thought to come from various stages of processing, including semantics. Two-to-one response mappings, in which two response-set colors share a common response location, have been used to isolate stimulus-stimulus (semantic) from stimulus-response conflict in the Stroop task. However, the use of congruent trials as a baseline means that the measured effects could be exaggerated by facilitation, and recent research using neutral, non-color-word trials as a baseline has supported this notion. In the present study, we sought to provide evidence for stimulus-stimulus conflict using an oculomotor Stroop task and an early, preresponse pupillometric measure of effort. The results provided strong (Bayesian) evidence for no statistical difference between two-to-one response-mapping trials and neutral trials in both saccadic response latencies and preresponse pupillometric measures, supporting the notion that the difference between same-response and congruent trials indexes facilitation in congruent trials, and not stimulus-stimulus conflict, thus providing evidence against the presence of semantic conflict in the Stroop task. We also demonstrated the utility of preresponse pupillometry in measuring Stroop interference, supporting the idea that pupillary effects are not simply a residue of making a response.
Cheatham, M. A.; Katz, E. D.; Charaziak, K.; Dallos, P.; Siegel, J. H.
Stimulus frequency otoacoustic emissions (SFOAE) were used to assay cochlear function in wildtype and prestin knockin (KI) mice. The latter contain a mutated form of the outer hair cell (OHC) motor protein (V499G/Y501H) with significantly reduced activity. Because several genetic mutations cause accelerated OHC death, it is beneficial to perform experiments in young mice without surgical intervention. Inasmuch as SFOAE thresholds are elevated by only 30 dB in KIs, it is possible to obtain SFOAE tuning functions in these animals. This approach allows sensitivity/frequency selectivity to be assayed within the basilar membane-OHC-tectorial membrane feedback loop, thereby providing information about signal processing prior to inner hair cell stimulation and auditory nerve activation.
Jones, T A; Schiltz, T
A simple method of generating precisely defined pulsed linear acceleration stimuli was developed and used to study vestibular responses to cranial acceleration. Electromechanical shakers were coupled to a stimulus platform. The platform, in turn, was used to couple stimuli to the skull. Movements were controlled by a voltage waveform (V(t] applied to shakers. Software algorithms were used to synthesize voltage functions (V(t]. The resulting acceleration was monitored [a(t)] and used to generate velocity [v(t)] and position [x(t)] functions (first and second integrals of a(t), respectively). The characteristics of stimuli used in physiological experiments are described. The system provides precise control of the timing and amplitude of acceleration, velocity and position pulses to the cranium and has proved to be valuable in developing noninvasive electrophysiological measures of peripheral and central vestibular function.
Harding, Jay W; Wacker, David P; Berg, Wendy K; Rick, Gary; Lee, John F
The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack. During baseline, the students received no feedback on their responses in either condition. During the intervention phase, the students received differential reinforcement in the form of instructor feedback for each different punching or kicking technique they performed during a session of the drill condition, but no reinforcement was provided for techniques in the sparring condition. Results showed that both students increased the number of different techniques they performed when reinforcement and extinction procedures were conducted during the drill condition, and that this increase in response variability generalized to the sparring condition.
Bergevin, Christopher; Shera, Christopher A.
Although lizards lack the basilar-membrane traveling waves evident in mammals, their ears produce stimulus-frequency otoacoustic emissions (SFOAEs) with latencies comparable to those measured in many mammals (1-2 ms or greater). To probe the origin of these relatively long OAE delays, we developed a model of SFOAE generation in the gecko. The model inner ear comprises a collection of linear, coupled oscillators (hair bundles and associated tectorium) whose effective damping manifests a small degree of irregularity. The model reproduces the major qualitative features of gecko SFOAEs, including their substantial delays. The SFOAE delays predicted by the model increase with the assumed sharpness of tuning, reflecting the build-up time associated with mechanical resonance.
Hahn, Jin S; Hanauer, André
The Coffin-Lowry syndrome (CLS) is a rare but well-defined X-linked semidominant syndrome characterized by psychomotor and growth retardation, and progressive skeletal changes. CLS is caused by loss of function mutations in the Rps6ka3 gene encoding the ribosomal S6 kinase 2 (RSK2) protein. A distinctive paroxysmal disorder has been described in some CLS patients, characterized by episodes of sudden falling, without apparent alteration of consciousness, usually induced by unexpected tactile or auditory stimuli. Duration of episodes is very short, usually lasting a few seconds. The appellation "Stimulus-induced drop episodes" (SIDEs) was proposed for these non-epileptic events in CLS patients. SIDEs are clinically heterogeneous; with some patients exhibiting cataplexy-like events characterized by sudden hypotonia and collapse, and others hyperekplexia-like episodes with a startle response. The pathophysiology of SIDEs is not well understood.
Bulens, C; Meerwaldt, J D; Van der Wildt, G J
We studied the effect of stimulus orientation on contrast sensitivity function in 21 patients with Parkinson's disease and in 10 normal subjects. This was done by measuring contrast sensitivity over a range of spatial frequencies for vertical and horizontal sine wave grating stimuli. There was a great test-retest consistency in normal subjects and patients. Fifteen of the 21 patients showed contrast sensitivity deficit in at least one eye. Orientation-specific loss was demonstrated in 17 of the 25 "affected" eyes. The most frequent type of orientation-specific loss was a notch defect, which preferentially affected the middle spatial frequencies. We attribute orientation-specific and spatial frequency-selective loss in Parkinson's disease to a functional disruption of neurons on the visual cortex.
Quian Quiroga, R.
We present a method for the analysis of electroencephalograms (EEG). In particular, small signals due to stimulation, so-called evoked potentials (EPs), have to be detected in the background EEG. This is achieved by using a denoising implementation based on the wavelet decomposition. One recording of visual evoked potentials, and recordings of auditory evoked potentials from four subjects corresponding to different age groups are analyzed. We find higher variability in older individuals. Moreover, since the EPs are identified at the single stimulus level (without need of ensemble averaging), this will allow the calculation of better resolved averages. Since the method is parameter free (i.e. it does not need to be adapted to the particular characteristics of each recording), implementations in clinical settings are imaginable.
Samson, Andrea C; Hegenloh, Michael
The present paper aims to investigate whether individuals with Asperger syndrome (AS) show global humor processing deficits or whether humor comprehension and appreciation depends on stimulus characteristics. Non-verbal visual puns, semantic and Theory of Mind cartoons were rated on comprehension, funniness and the punchlines were explained. AS individuals did not differ to the control group in humor appreciation of visual puns. However, they had difficulty understanding and appreciating Theory of Mind cartoons and provided mentalistic explanations less frequently than controls suggesting that humor processing is strongly related to the cognitive requirements that the stimuli pose on the perceiver. Furthermore, AS individuals referred in all conditions more frequently to non-joke relevant details. Therefore, humor processing is also influenced by their detail-oriented processing style.
Leung, Hiu Tin; Westbrook, R Frederick
A series of experiments used the compound test procedure (Rescorla, 2002) to measure the size of spontaneous recovery of freezing responses by rats to a latently inhibited and/or extinguished conditioned stimulus (CS). The size of recovery was greater: to a pre-exposed and conditioned CS than to a CS just conditioned or just pre-exposed; to an extensively pre-exposed or extinguished CS than to a moderately pre-exposed or extinguished CS; and to a pre-exposed and extinguished CS than to a CS just pre-exposed or just extinguished. These results show that the size of recovery is proportional to the size of the depression produced by CS-alone exposures regardless of whether they occurred before, after, or both before and after conditioning. The results are discussed in terms of some contemporary models of recovery and of the inferences permitted by the use of the compound assessment technique.
Singh, Vijay; Tchernookov, Martin; Nemenman, Ilya
In the context of neural information processing, it has been observed that, compared to the case of independent receptors, correlated receptors can often carry more information about the stimulus. We explore similar ideas in the context of molecular information processing, analyzing a cell with receptors whose activity is intrinsically negatively correlated because they compete for the same ligand molecules. We show analytically that, in case the involved biochemical interactions are linear, the information between the number of molecules captured by the receptors and the ligand concentration does not depend on correlations among the receptors. For a nonlinear kinetic network, correlations similarly do not change the amount of information for observation times much shorter or much longer than the characteristic time scale of ligand molecule binding and unbinding. However, at intermediate times, correlations can increase the amount of available information. This work has been supported by the James S McDonnell foundation.
Keller, Andreas J; Houlton, Rachael; Kampa, Björn M; Lesica, Nicholas A; Mrsic-Flogel, Thomas D; Keller, Georg B; Helmchen, Fritjof
A general principle of sensory processing is that neurons adapt to sustained stimuli by reducing their response over time. Most of our knowledge on adaptation in single cells is based on experiments in anesthetized animals. How responses adapt in awake animals, when stimuli may be behaviorally relevant or not, remains unclear. Here we show that contrast adaptation in mouse primary visual cortex depends on the behavioral relevance of the stimulus. Cells that adapted to contrast under anesthesia maintained or even increased their activity in awake naïve mice. When engaged in a visually guided task, contrast adaptation re-occurred for stimuli that were irrelevant for solving the task. However, contrast adaptation was reversed when stimuli acquired behavioral relevance. Regulation of cortical adaptation by task demand may allow dynamic control of sensory-evoked signal flow in the neocortex. DOI: http://dx.doi.org/10.7554/eLife.21589.001 PMID:28130922
Dube, William V; Farber, Rachel S; Mueller, Marlana R; Grant, Eileen; Lorin, Lucy; Deutsch, Curtis K
Stimulus overselectivity refers to maladaptive narrow attending that is a common learning problem among children with intellectual disabilities and frequently associated with autism. The present study contrasted overselectivity among groups of children with autism, Down syndrome, and typical development. The groups with autism and Down syndrome were matched for intellectual level, and all three groups were matched for developmental levels on tests of nonverbal reasoning and receptive vocabulary. Delayed matching-to-sample tests presented color/form compounds, printed words, photographs of faces, Mayer-Johnson Picture Communication Symbols, and unfamiliar black forms. No significant differences among groups emerged for test accuracy scores. Overselectivity was not statistically overrepresented among individuals with autism in contrast to those with Down syndrome or typically developing children.
Hsieh and Allport studied shifts of attention in semantic space, using a semantic monitoring task based on rapid, serial, visually presented sequences of words. They reported that following a shift of criterion, accuracy of semantic monitoring dropped abruptly to a low level, then gradually recovered to reach the preshift level over successive stimuli in the sequence. They further examined the nature of the recovery of accuracy following a shift of criterion. Despite the striking results they obtained, some problems of their design remained. Hence, the current research replicated Hsieh and Allport's experiments with some modifications and showed that a shift of semantic criterion in a rapidly presented sequence indeed appears to be stimulus-driven rather than an autonomous process.
Schölvinck, M L; Friston, K J; Rees, G
Spontaneous activity in the resting human brain has been studied extensively; however, how such activity affects the local processing of a sensory stimulus is relatively unknown. Here, we examined the impact of spontaneous activity in primary visual cortex on neuronal and behavioural responses to a simple visual stimulus, using functional MRI. Stimulus-evoked responses remained essentially unchanged by spontaneous fluctuations, combining with them in a largely linear fashion (i.e., with little evidence for an interaction). However, interactions between spontaneous fluctuations and stimulus-evoked responses were evident behaviourally; high levels of spontaneous activity tended to be associated with increased stimulus detection at perceptual threshold. Our results extend those found in studies of spontaneous fluctuations in motor cortex and higher order visual areas, and suggest a fundamental role for spontaneous activity in stimulus processing.
Previous research indicated that congruency between stimulus location and response position (spatial stimulus-response correspondence [SRC]) and stimulus motion and response movement congruency (motion SRC) are distinct SRC phenomena. This study further explored this issue and tested whether these two SRC effects are independent. This was conducted by investigating these two SRC effects in a single task. A stimulus with leftward or rightward motion was presented on the left or the right side of the screen and the participant had to move the joysticks held with the left and right hands leftward or rightward in response to the stimulus color. In this setting, the stimulus and response shared two types of correspondence: spatial and motion. The results demonstrated that two SRC effects occurred and interacted (interaction evident only in reaction times [RTs]). RT distribution analysis and accuracy delta plots for each SRC effect indicated that spatial and motion SRC are distinct phenomena based on different processes.
van der Aa, Jeroen; Honing, Henkjan; ten Cate, Carel
Perceiving temporal regularity in an auditory stimulus is considered one of the basic features of musicality. Here we examine whether zebra finches can detect regularity in an isochronous stimulus. Using a go/no go paradigm we show that zebra finches are able to distinguish between an isochronous and an irregular stimulus. However, when the tempo of the isochronous stimulus is changed, it is no longer treated as similar to the training stimulus. Training with three isochronous and three irregular stimuli did not result in improvement of the generalization. In contrast, humans, exposed to the same stimuli, readily generalized across tempo changes. Our results suggest that zebra finches distinguish the different stimuli by learning specific local temporal features of each individual stimulus rather than attending to the global structure of the stimuli, i.e., to the temporal regularity.
Shah, A. S.; Lakatos, P.; McGinnis, T.; O'Connell, N.; Mills, A.; Knuth, K. H.; Chen, C.; Karmos, G.; Schroeder, C. E.
Cortical gamma band oscillations have been recorded in sensory cortices of cats and monkeys, and are thought to aid in perceptual binding. Gamma activity has also been recorded in the rat hippocampus and entorhinal cortex, where it has been shown, that field gamma power is modulated at theta frequency. Since the power of gamma activity in the sensory cortices is not constant (gamma-bursts). we decided to examine the relationship between gamma power and the phase of low frequency oscillation in the auditory cortex of the awake macaque. Macaque monkeys were surgically prepared for chronic awake electrophysiological recording. During the time of the experiments. linear array multielectrodes were inserted in area AI to obtain laminar current source density (CSD) and multiunit activity profiles. Instantaneous theta and gamma power and phase was extracted by applying the Morlet wavelet transformation to the CSD. Gamma power was averaged for every 1 degree of low frequency oscillations to calculate power-phase relation. Both gamma and theta-delta power are largest in the supragranular layers. Power modulation of gamma activity is phase locked to spontaneous, as well as stimulus-related local theta and delta field oscillations. Our analysis also revealed that the power of theta oscillations is always largest at a certain phase of delta oscillation. Auditory stimuli produce evoked responses in the theta band (Le., there is pre- to post-stimulus addition of theta power), but there is also indication that stimuli may cause partial phase re-setting of spontaneous delta (and thus also theta and gamma) oscillations. We also show that spontaneous oscillations might play a role in the processing of incoming sensory signals by 'preparing' the cortex.
Mc Govern, Eavan M; Butler, John S; Beiser, Ines; Williams, Laura; Quinlivan, Brendan; Narasiham, Shruti; Beck, Rebecca; O'Riordan, Sean; Reilly, Richard B; Hutchinson, Michael
The temporal discrimination threshold (TDT) is the shortest time interval at which an individual detects two stimuli to be asynchronous (normal = 30-50 ms). It has been shown to be abnormal in patients with disorders affecting the basal ganglia including adult onset idiopathic focal dystonia (AOIFD). Up to 97% of patients have an abnormal TDT with age- and sex-related penetrance in unaffected relatives, demonstrating an autosomal dominant inheritance pattern. These findings support the use of the TDT as a pre-clinical biomarker for AOIFD. The usual stimulus presentation method involves the presentation of progressively asynchronous stimuli; when three sequential stimuli are reported asynchronous is taken as a participant's TDT. To investigate the robustness of the 'staircase' method of presentation, we introduced a method of randomised presentation order to explore any potential 'learning effect' that may be associated with this existing method. The aim of this study was to investigate differences in temporal discrimination using two methods of stimulus presentation. Thirty healthy volunteers were recruited to the study (mean age 33.73 ± 3.4 years). Visual and tactile TDT testing using a staircase and randomised method of presentation order was carried out in a single session. There was a strong relationship between the staircase and random method for TDT values. This observed consistency between testing methods suggests that the existing experimental approach is a robust method of recording an individual's TDT. In addition, our newly devised randomised paradigm is a reproducible and more efficient method for data acquisition in the clinic setting. However, the two presentation methods yield different absolute TDT results and either of the two methods should be used uniformly in all participants in any one particular study.
Medan, Violeta; Oliva, Damián; Tomsic, Daniel
In the grapsid crab Chasmagnathus, a visual danger stimulus elicits a strong escape response that diminishes rapidly on stimulus repetition. This behavioral modification can persist for several days as a result of the formation of an associative memory. We have previously shown that a generic group of large motion-sensitive neurons from the lobula of the crab respond to visual stimuli and accurately reflect the escape performance. Additional evidence indicates that these neurons play a key role in visual memory and in the decision to initiate an escape. Although early studies recognized that the group of lobula giant (LG) neurons consisted of different classes of motion-sensitive cells, a distinction between these classes has been lacking. Here, we recorded in vivo the responses of individual LG neurons to a wide range of visual stimuli presented in different segments of the animal's visual field. Physiological characterizations were followed by intracellular dye injections, which permitted comparison of the functional and morphological features of each cell. All LG neurons consisted of large tangential arborizations in the lobula with axons projecting toward the midbrain. Functionally, these cells proved to be more sensitive to single objects than to flow field motion. Despite these commonalities, clear differences in morphology and physiology allowed us to identify four distinct classes of LG neurons. These results will permit analysis of the role of each neuronal type for visually guided behaviors and will allow us to address specific questions on the neuronal plasticity of LGs that underlie the well-recognized memory model of the crab.
The purpose of this study was to assess the usefulness of a new technique that measured various sizes of the soleus H-reflex, while monitoring the stimulus condition. Eight healthy volunteers participated in this experiment. In the new technique, an above-motor-threshold conditioning stimulus was given to the tibial nerve 10-12 ms after a below-motor-threshold test stimulus. The conditioning stimulus evoked a direct M-wave, which was followed by a test-stimulus-evoked H-reflex. This reflex was followed by a conditioning stimulus-evoked H-reflex. The amount of the voluntary-contraction-induced facilitation of the H-reflex was similar for both the new technique and conventional technique, in which an above-motor-threshold test stimulus was given without a conditioning stimulus. Using the new technique, we found that the amount of facilitation increased linearly with the size of the test H-reflex. This technique allows us to evoke various sizes of H-reflex while monitoring a stimulus condition, and is useful for measuring H-reflexes during voluntary movement.