Beauty at a glance: The feeling of beauty and the amplitude of pleasure are independent of stimulus duration.

PubMed

Brielmann, Aenne A; Vale, Lauren; Pelli, Denis G

2017-12-01

Over time, how does beauty develop and decay? Common sense suggests that beauty is intensely felt only after prolonged experience of the object. Here, we present one of various stimuli for a variable duration (1-30 s), measure the observers' pleasure over time, and, finally, ask whether they felt beauty. On each trial, participants (N = 21) either see an image that they had chosen as "movingly beautiful," see an image with prerated valence, or suck a candy. During the stimulus and a further 60 s, participants rate pleasure continuously using a custom touchscreen web app, EmotionTracker.com. After each trial, participants judge whether they felt beauty. Across all stimulus kinds, durations, and beauty responses, the dynamic pleasure rating has a stereotypical time course that is well fit by a one-parameter model with a brief exponential onset (roughly 2.5 s), a sustained plateau during stimulus presentation, and a long exponential decay (roughly 70 s). Across conditions, only the plateau amplitude varies. Beauty and pleasure amplitude are nearly independent of stimulus duration. The final beauty rating is positively correlated with pleasure amplitude (r = 0.60), and nearly independent of duration (r = 0.10). Beauty's independence from duration is unlike Bentham's 18th-century notion of value (utility), which he supposed to depend on the product of pleasure amplitude and duration. Participants report having felt pleasure as strongly after a mere 1 s stimulus as after longer durations, up to 30 s. Thus, we find that amplitude of pleasure is independent of stimulus duration.

Temporal expectancy in the context of a theory of visual attention

PubMed Central

Vangkilde, Signe; Petersen, Anders; Bundesen, Claus

2013-01-01

Temporal expectation is expectation with respect to the timing of an event such as the appearance of a certain stimulus. In this paper, temporal expectancy is investigated in the context of the theory of visual attention (TVA), and we begin by summarizing the foundations of this theoretical framework. Next, we present a parametric experiment exploring the effects of temporal expectation on perceptual processing speed in cued single-stimulus letter recognition with unspeeded motor responses. The length of the cue–stimulus foreperiod was exponentially distributed with one of six hazard rates varying between blocks. We hypothesized that this manipulation would result in a distinct temporal expectation in each hazard rate condition. Stimulus exposures were varied such that both the temporal threshold of conscious perception (t0 ms) and the perceptual processing speed (v letters s−1) could be estimated using TVA. We found that the temporal threshold t0 was unaffected by temporal expectation, but the perceptual processing speed v was a strikingly linear function of the logarithm of the hazard rate of the stimulus presentation. We argue that the effects on the v values were generated by changes in perceptual biases, suggesting that our perceptual biases are directly related to our temporal expectations. PMID:24018716

The Effects of Stimulus Presentation Rate on the Short-Term Memory of Learning Disabled Children.

ERIC Educational Resources Information Center

Tarver, Sara G.; Ellsworth, Patricia S.

To test the hypothesis that the developmental lag in verbal rehearsal which has been documented for the learning disabled is due to a naming speed deficit (i.e., slow retrieval of stimulus names), the serial recall performance of 64 learning disabled children at four grade levels (1, 3, 5, and 7) was compared under three stimulus presentation…

Second-order schedules: discrimination of components1

PubMed Central

Squires, Nancy; Norborg, James; Fantino, Edmund

1975-01-01

Pigeons were exposed to a series of second-order schedules in which the completion of a fixed number of fixed-interval components produced food. In Experiment 1, brief (2 sec) stimulus presentations occurred as each fixed-interval component was completed. During the brief-stimulus presentation terminating the last fixed-interval component, a response was required on a second key, the brief-stimulus key, to produce food. Responses on the brief-stimulus key before the last brief-stimulus presentation had no scheduled consequences, but served as a measure of the extent to which the final component was discriminated from preceding components. Whether there were one, two, four, or eight fixed-interval components, responses on the brief-stimulus key occurred during virtually every brief-stimulus presentation. In Experiment 2, an attempt was made to punish unnecessary responses on the brief-stimulus key, i.e., responses on the brief-stimulus key that occurred before the last component. None of the pigeons learned to withhold these responses, even though they produced a 15-sec timeout and loss of primary reinforcement. In Experiment 3, different key colors were associated with each component of a second-order schedule (a chain schedule). In contrast to Experiment 1, brief-stimulus key responses were confined to the last component. It was concluded that pigeons do not discriminate well between components of second-order schedules unless a unique exteroceptive cue is provided for each component. The relative discriminability of the components may account for the observed differences in initial-component response rates between comparable brief-stimulus, tandem, and chain schedules. PMID:16811868

Is Conscious Stimulus Identification Dependent on Knowledge of the Perceptual Modality? Testing the “Source Misidentification Hypothesis”

PubMed Central

Overgaard, Morten; Lindeløv, Jonas; Svejstrup, Stinna; Døssing, Marianne; Hvid, Tanja; Kauffmann, Oliver; Mouridsen, Kim

2013-01-01

This paper reports an experiment intended to test a particular hypothesis derived from blindsight research, which we name the “source misidentification hypothesis.” According to this hypothesis, a subject may be correct about a stimulus without being correct about how she had access to this knowledge (whether the stimulus was visual, auditory, or something else). We test this hypothesis in healthy subjects, asking them to report whether a masked stimulus was presented auditorily or visually, what the stimulus was, and how clearly they experienced the stimulus using the Perceptual Awareness Scale (PAS). We suggest that knowledge about perceptual modality may be a necessary precondition in order to issue correct reports of which stimulus was presented. Furthermore, we find that PAS ratings correlate with correctness, and that subjects are at chance level when reporting no conscious experience of the stimulus. To demonstrate that particular levels of reporting accuracy are obtained, we employ a statistical strategy, which operationally tests the hypothesis of non-equality, such that the usual rejection of the null-hypothesis admits the conclusion of equivalence. PMID:23508677

Code-modulated visual evoked potentials using fast stimulus presentation and spatiotemporal beamformer decoding.

PubMed

Wittevrongel, Benjamin; Van Wolputte, Elia; Van Hulle, Marc M

2017-11-08

When encoding visual targets using various lagged versions of a pseudorandom binary sequence of luminance changes, the EEG signal recorded over the viewer's occipital pole exhibits so-called code-modulated visual evoked potentials (cVEPs), the phase lags of which can be tied to these targets. The cVEP paradigm has enjoyed interest in the brain-computer interfacing (BCI) community for the reported high information transfer rates (ITR, in bits/min). In this study, we introduce a novel decoding algorithm based on spatiotemporal beamforming, and show that this algorithm is able to accurately identify the gazed target. Especially for a small number of repetitions of the coding sequence, our beamforming approach significantly outperforms an optimised support vector machine (SVM)-based classifier, which is considered state-of-the-art in cVEP-based BCI. In addition to the traditional 60 Hz stimulus presentation rate for the coding sequence, we also explore the 120 Hz rate, and show that the latter enables faster communication, with a maximal median ITR of 172.87 bits/min. Finally, we also report on a transition effect in the EEG signal following the onset of the stimulus sequence, and recommend to exclude the first 150 ms of the trials from decoding when relying on a single presentation of the stimulus sequence.

Novel stimuli are negative stimuli: evidence that negative affect is reduced in the mere exposure effect.

PubMed

Robinson, Brent M; Elias, Lorin J

2005-04-01

Repeated exposure of a nonreinforced stimulus results in an increased preference for that stimulus, the mere exposure effect. The present study repeatedly presented positive, negative, and neutrally affective faces to 48 participants while they made judgments about the emotional expression. Participants then rated the likeability of novel neutrally expressive faces and some of these previously presented faces, this time in their neutral expression. Faces originally presented as happy were rated as the most likeable, followed by faces originally presented as neutral. Negative and novel faces were not rated significantly differently from each other. These findings support the notion that the increase in preference towards repeatedly presented stimuli is the result of the reduction in negative affect, consistent with the modified two-factor uncertainty-reduction model and classical conditioning model of the mere exposure effect.

Testing a Poisson Counter Model for Visual Identification of Briefly Presented, Mutually Confusable Single Stimuli in Pure Accuracy Tasks

ERIC Educational Resources Information Center

Kyllingsbaek, Soren; Markussen, Bo; Bundesen, Claus

2012-01-01

The authors propose and test a simple model of the time course of visual identification of briefly presented, mutually confusable single stimuli in pure accuracy tasks. The model implies that during stimulus analysis, tentative categorizations that stimulus i belongs to category j are made at a constant Poisson rate, v(i, j). The analysis is…

Stimulus Characteristics Affect Humor Processing in Individuals with Asperger Syndrome

ERIC Educational Resources Information Center

Samson, Andrea C.; Hegenloh, Michael

2010-01-01

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…

Influence of cochlear traveling wave and neural adaptation on auditory brainstem responses.

PubMed

Junius, Dirk; Dau, Torsten

2005-07-01

The present study investigates the relationship between evoked responses to transient broadband chirps and responses to the same chirps when embedded in longer-duration stimuli. It examines to what extent the responses to the composite stimuli can be explained by a linear superposition of the responses to the single components, as a function of stimulus level. In the first experiment, a single rising chirp was temporally and spectrally embedded in two steady-state tones. In the second experiment, the stimulus consisted of a continuous alternating train of chirps: each rising chirp was followed by the temporally reversed (falling) chirp. In both experiments, the transitions between stimulus components were continuous. For stimulation levels up to approximately 70 dB SPL, the responses to the embedded chirp corresponded to the responses to the single chirp. At high stimulus levels (80-100 dB SPL), disparities occurred between the responses, reflecting a nonlinearity in the processing when neural activity is integrated across frequency. In the third experiment, the effect of within-train rate on wave-V response was investigated. The response to the chirp presented at a within-train rate of 95 Hz exhibited the same amplitude as that to the chirp presented in the traditional single-stimulus paradigm at a rate of 13 Hz. For a corresponding experiment with bandlimited chirps of 4 ms duration, where the within-train rate was 250 Hz, a clear reduction of the response amplitude was observed. This nonlinearity in terms of temporal processing most likely reflects effects of short-term adaptation. Overall, the results of the present study further demonstrate the importance of cochlear processing for the formation of brainstem potentials. The data may provide constraints on future models of peripheral processing in the human auditory system. The findings might also be useful for the development of effective stimulation paradigms in clinical applications.

The impact of subliminal effect images in voluntary vs. stimulus-driven actions.

PubMed

Le Bars, Solène; Hsu, Yi-Fang; Waszak, Florian

2016-11-01

According to the ideomotor theory, actions are represented in terms of their sensory effects. In the current study we tested whether subliminal effect images influence action control (1) at early and/or late preparatory stages of (2) voluntary actions or stimulus-driven actions (3) with or without Stimulus-Response (S-R) compatibility. In Experiment 1, participants were presented at random with 50% of S-R compatible stimulus-driven action trials and 50% of voluntary action trials. The actions' effects (i.e. up- or down-pointing arrows) were presented subliminally before each action (i.e. a keypress). In voluntary actions, participants selected more often the action congruent with the prime when it was presented at long intervals before the action. Moreover they responded faster in prime-congruent than in prime-incongruent trials when primes were presented at short intervals before the action. In Experiment 2, participants were only presented with stimulus-driven action trials, with or without S-R compatibility. In stimulus-driven action trials with S-R compatibility (e.g., left-pointing arrow signaling a left keypress), subliminal action-effects did not generate any significant effect on RTs or error rates. On the other hand, in stimulus-driven action trials without S-R compatibility (e.g., letter "H" signaling a left keypress), participants were significantly faster in prime-congruent trials when primes were presented at the shortest time interval before the action. These results suggest that subliminal effect images facilitate voluntary action preparation on an early and a late level. Stimulus-driven action preparation is influenced on a late level only, and only if there is no compatibility between the stimulus and the motor response, that is when the response is not automatically triggered by the common properties existing between the stimulus and the required action. Copyright © 2016 Elsevier B.V. All rights reserved.

The paradoxical effect of low reward probabilities in suboptimal choice.

PubMed

Fortes, Inês; Pinto, Carlos; Machado, Armando; Vasconcelos, Marco

2018-04-01

When offered a choice between 2 alternatives, animals sometimes prefer the option yielding less food. For instance, pigeons and starlings prefer an option that on 20% of the trials presents a stimulus always followed by food, and on the remaining 80% of the trials presents a stimulus never followed by food (the Informative Option), over an option that provides food on 50% of the trials regardless of the stimulus presented (the Noninformative Option). To explain this suboptimal behavior, it has been hypothesized that animals ignore (or do not engage with) the stimulus that is never followed by food in the Informative Option. To assess when pigeons attend to the stimulus usually not followed by food, we increased the probability of reinforcement, p, in the presence of that stimulus. Across 2 experiments, we found that the value of the Informative Option decreased with p. To account for the results, we added to the Reinforcement Rate Model (and also to the Hyperbolic Discounting Model) an engagement function, f(p), that specified the likelihood the animal attends to a stimulus followed by reward with probability p, and then derived the model predictions for 2 forms of f(p), a linear function, and an all-or-none threshold function. Both models predicted the observed findings with a linear engagement function: The higher the probability of reinforcement after a stimulus, the higher the probability of engaging the stimulus, and, surprisingly, the less the value of the option comprising the stimulus. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Increased conditioned pain modulation in athletes.

PubMed

Flood, Andrew; Waddington, Gordon; Thompson, Kevin; Cathcart, Stuart

2017-06-01

The potential relationship between physical activity and endogenous pain modulatory capacity remains unclear. Therefore, the aim of the current study was to compare the pain modulatory responses of athletes and non-athletes. Conditioned pain modulation (CPM) was assessed in 15 athletes and 15 non-athletes at rest. Participation was restricted to pain-free males between 18 and 40 years of age. To measure CPM capacity, a sequential CPM testing protocol was implemented, whereby a test stimulus (pressure pain threshold [PPT]) was presented before and immediately after a conditioning stimulus (4-min cold-pressor test). Pain intensity ratings were obtained at 15-s intervals throughout the cold-pressor task using a numerical rating scale. Athletes demonstrated higher baseline PPTs compared to non-athletes (P = .03). Athletes also gave lower mean (P < .001) and maximum (P < .001) pain intensity ratings in response to the conditioning stimulus. The conditioning stimulus had a stronger inhibitory effect on the test stimulus in athletes, showing enhanced CPM in athletes compared to non-athletes (P < .05). This finding of enhanced CPM in athletes helps clarify previous mixed findings. Potential implications for exercise performance and injury are discussed.

Selective attention and the auditory vertex potential. 1: Effects of stimulus delivery rate

NASA Technical Reports Server (NTRS)

Schwent, V. L.; Hillyard, S. A.; Galambos, R.

1975-01-01

Enhancement of the auditory vertex potentials with selective attention to dichotically presented tone pips was found to be critically sensitive to the range of inter-stimulus intervals in use. Only at the shortest intervals was a clear-cut enhancement of the latency component to stimuli observed for the attended ear.

Dissociable effects of inter-stimulus interval and presentation duration on rapid face categorization.

PubMed

Retter, Talia L; Jiang, Fang; Webster, Michael A; Rossion, Bruno

2018-04-01

Fast periodic visual stimulation combined with electroencephalography (FPVS-EEG) has unique sensitivity and objectivity in measuring rapid visual categorization processes. It constrains image processing time by presenting stimuli rapidly through brief stimulus presentation durations and short inter-stimulus intervals. However, the selective impact of these temporal parameters on visual categorization is largely unknown. Here, we presented natural images of objects at a rate of 10 or 20 per second (10 or 20 Hz), with faces appearing once per second (1 Hz), leading to two distinct frequency-tagged EEG responses. Twelve observers were tested with three squarewave image presentation conditions: 1) with an ISI, a traditional 50% duty cycle at 10 Hz (50-ms stimulus duration separated by a 50-ms ISI); 2) removing the ISI and matching the rate, a 100% duty cycle at 10 Hz (100-ms duration with 0-ms ISI); 3) removing the ISI and matching the stimulus presentation duration, a 100% duty cycle at 20 Hz (50-ms duration with 0-ms ISI). The face categorization response was significantly decreased in the 20 Hz 100% condition. The conditions at 10 Hz showed similar face-categorization responses, peaking maximally over the right occipito-temporal (ROT) cortex. However, the onset of the 10 Hz 100% response was delayed by about 20 ms over the ROT region relative to the 10 Hz 50% condition, likely due to immediate forward-masking by preceding images. Taken together, these results help to interpret how the FPVS-EEG paradigm sets temporal constraints on visual image categorization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Roles of stimulus control and reinforcement frequency in modulating the behavioral effects of d-amphetamine in the rat

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

Rees, D.C.; Wood, R.W.; Laties, V.G.

1984-03-01

The behavioral effects of d-amphetamine have been shown to be modulated by stimulus control, with less impairment of performance occurring when control is great. When the fixed-consecutive-number schedule is used (on which at least a specified consecutive number of responses must be made on one operandum before a single response on another will produce a reinforcer), response rate tends to invariant but reinforcement frequency is not. This study asks whether the differences in reinforcement frequency that usually accompany changes in stimulus control could themselves be responsible for the performance differences. Two versions of the fixed-consecutive-number schedule of reinforcement were combinedmore » into a multiple schedule within which stimulus control was varied but differences in reinforcement frequency were minimized by omitting some reinforcer deliveries during the component that usually had the higher reinforcement frequency. In one component, a compound discriminative stimulus was added with the eighth consecutive response on the first lever, a single response on the second lever was then reinforced. In the other component, no such stimulus was presented. With no added stimulus, large decreases occurred in the number of runs satisfying the minimum requirement for reinforcement at doses of drug that produced only minimal changes when an added stimulus controlled behavior. Thus, increased stimulus control diminishes the behavioral changes produced by d-amphetamine even when the possible contribution by baseline reinforcement rate is minimized. 17 references, 6 figures, 4 tables.« less

The specificity of stimulus-specific adaptation in human auditory cortex increases with repeated exposure to the adapting stimulus.

PubMed

Briley, Paul M; Krumbholz, Katrin

2013-12-01

The neural response to a sensory stimulus tends to be more strongly reduced when the stimulus is preceded by the same, rather than a different, stimulus. This stimulus-specific adaptation (SSA) is ubiquitous across the senses. In hearing, SSA has been suggested to play a role in change detection as indexed by the mismatch negativity. This study sought to test whether SSA, measured in human auditory cortex, is caused by neural fatigue (reduction in neural responsiveness) or by sharpening of neural tuning to the adapting stimulus. For that, we measured event-related cortical potentials to pairs of pure tones with varying frequency separation and stimulus onset asynchrony (SOA). This enabled us to examine the relationship between the degree of specificity of adaptation as a function of frequency separation and the rate of decay of adaptation with increasing SOA. Using simulations of tonotopic neuron populations, we demonstrate that the fatigue model predicts independence of adaptation specificity and decay rate, whereas the sharpening model predicts interdependence. The data showed independence and thus supported the fatigue model. In a second experiment, we measured adaptation specificity after multiple presentations of the adapting stimulus. The multiple adapters produced more adaptation overall, but the effect was more specific to the adapting frequency. Within the context of the fatigue model, the observed increase in adaptation specificity could be explained by assuming a 2.5-fold increase in neural frequency selectivity. We discuss possible bottom-up and top-down mechanisms of this effect.

The rate of change of vergence-accommodation conflict affects visual discomfort.

PubMed

Kim, Joohwan; Kane, David; Banks, Martin S

2014-12-01

Stereoscopic (S3D) displays create conflicts between the distance to which the eyes must converge and the distance to which the eyes must accommodate. Such conflicts require the viewer to overcome the normal coupling between vergence and accommodation, and this effort appears to cause viewer discomfort. Vergence-accommodation coupling is driven by the phasic components of the underlying control systems, and those components respond to relatively fast changes in vergence and accommodative stimuli. Given the relationship between phasic changes and vergence-accommodation coupling, we examined how the rate of change in the vergence-accommodation conflict affects viewer discomfort. We used a stereoscopic display that allows independent manipulation of the stimuli to vergence and accommodation. We presented stimuli that simulate natural viewing (i.e., vergence and accommodative stimuli changed together) and stimuli that simulate S3D viewing (i.e., vergence stimulus changes but accommodative stimulus remains fixed). The changes occurred at 0.01, 0.05, or 0.25 Hz. The lowest rate is too slow to stimulate the phasic components while the highest rate is well within the phasic range. The results were consistent with our expectation: somewhat greater discomfort was experienced when stimulus distance changed rapidly, particularly in S3D viewing when the vergence stimulus changed but the accommodative stimulus did not. These results may help in the generation of guidelines for the creation and viewing of stereo content with acceptable viewer comfort.

Encoding of the amplitude modulation of pulsatile electrical stimulation in the feline cochlear nucleus by neurons in the inferior colliculus; effects of stimulus pulse rate

NASA Astrophysics Data System (ADS)

McCreery, Douglas; Han, Martin; Pikov, Victor; Yadav, Kamal; Pannu, Satinderpall

2013-10-01

Objectives. Persons without a functional auditory nerve cannot benefit from cochlear implants, but some hearing can be restored by an auditory brainstem implant (ABI) with stimulating electrodes implanted on the surface of the cochlear nucleus (CN). Most users benefit from their ABI, but speech recognition tends to be poorer than for users of cochlear implants. Psychophysical studies suggest that poor modulation detection may contribute to the limited performance of ABI users. In a cat model, we determined how the pulse rate of the electrical stimulus applied within or on the CN affects temporal and rate encoding of amplitude modulation (AM) by neurons in the central nucleus of the inferior colliculus (ICC). Approach. Stimulating microelectrodes were implanted chronically in and on the cats' CN, and multi-site recording microelectrodes were implanted chronically into the ICC. Encoding of AM pulse trains by neurons in the ICC was characterized as vector strength (VS), the synchrony of neural activity with the AM, and as the mean rate of neuronal action potentials (neuronal spike rate (NSR)). Main results. For intranuclear microstimulation, encoding of AM as VS was up to 3 dB greater when stimulus pulse rate was increased from 250 to 500 pps, but only for neuronal units with low best acoustic frequencies, and when the electrical stimulation was modulated at low frequencies (10-20 Hz). For stimulation on the surface of the CN, VS was similar at 250 and 500 pps, and the dynamic range of the VS was reduced for pulse rates greater than 250 pps. Modulation depth was encoded strongly as VS when the maximum stimulus amplitude was held constant across a range of modulation depth. This ‘constant maximum’ protocol allows enhancement of modulation depth while preserving overall dynamic range. However, modulation depth was not encoded as strongly as NSR. Significance. The findings have implications for improved sound processors for present and future ABIs. The performance of ABIs may benefit from using pulse rates greater than those presently used in most ABIs, and by sound processing strategies that enhance the modulation depth of the electrical stimulus while preserving dynamic range.

Event-related brain responses to emotional words, pictures, and faces – a cross-domain comparison

PubMed Central

Bayer, Mareike; Schacht, Annekathrin

2014-01-01

Emotion effects in event-related brain potentials (ERPs) have previously been reported for a range of visual stimuli, including emotional words, pictures, and facial expressions. Still, little is known about the actual comparability of emotion effects across these stimulus classes. The present study aimed to fill this gap by investigating emotion effects in response to words, pictures, and facial expressions using a blocked within-subject design. Furthermore, ratings of stimulus arousal and valence were collected from an independent sample of participants. Modulations of early posterior negativity (EPN) and late positive complex (LPC) were visible for all stimulus domains, but showed clear differences, particularly in valence processing. While emotion effects were limited to positive stimuli for words, they were predominant for negative stimuli in pictures and facial expressions. These findings corroborate the notion of a positivity offset for words and a negativity bias for pictures and facial expressions, which was assumed to be caused by generally lower arousal levels of written language. Interestingly, however, these assumed differences were not confirmed by arousal ratings. Instead, words were rated as overall more positive than pictures and facial expressions. Taken together, the present results point toward systematic differences in the processing of written words and pictorial stimuli of emotional content, not only in terms of a valence bias evident in ERPs, but also concerning their emotional evaluation captured by ratings of stimulus valence and arousal. PMID:25339927

A method for achieving an order-of-magnitude increase in the temporal resolution of a standard CRT computer monitor.

PubMed

Fiesta, Matthew P; Eagleman, David M

2008-09-15

As the frequency of a flickering light is increased, the perception of flicker is replaced by the perception of steady light at what is known as the critical flicker fusion threshold (CFFT). This threshold provides a useful measure of the brain's information processing speed, and has been used in medicine for over a century both for diagnostic and drug efficacy studies. However, the hardware for presenting the stimulus has not advanced to take advantage of computers, largely because the refresh rates of typical monitors are too slow to provide fine-grained changes in the alternation rate of a visual stimulus. For example, a cathode ray tube (CRT) computer monitor running at 100Hz will render a new frame every 10 ms, thus restricting the period of a flickering stimulus to multiples of 20 ms. These multiples provide a temporal resolution far too low to make precise threshold measurements, since typical CFFT values are in the neighborhood of 35 ms. We describe here a simple and novel technique to enable alternating images at several closely-spaced periods on a standard monitor. The key to our technique is to programmatically control the video card to dynamically reset the refresh rate of the monitor. Different refresh rates allow slightly different frame durations; this can be leveraged to vastly increase the resolution of stimulus presentation times. This simple technique opens new inroads for experiments on computers that require more finely-spaced temporal resolution than a monitor at a single, fixed refresh rate can allow.

Tooth pulp stimulation as an unconditioned stimulus in defensive instrumental conditioning.

PubMed

Jastreboff, P J; Keller, O; Zieliński, K

1977-01-01

In an experiment performed on five cats, stable escape and avoidance reflexes in a bar-pressing situation were established using tooth pulp electric stimulation as the unconditioned stimulus. The influence of changes in parameters of the unconditioned stimulus (current intensity, single pulse and train durations, frequency of pulses and rate of train presentations) on unconditioned and instrumental responses was analysed in three additional subjects. Among other relationships the dependence of the threshold of bar press responses on the amount of charge in a single pulse was determined.

Stimulus and recording variables and their effects on mammalian vestibular evoked potentials

NASA Technical Reports Server (NTRS)

Jones, Sherri M.; Subramanian, Geetha; Avniel, Wilma; Guo, Yuqing; Burkard, Robert F.; Jones, Timothy A.

2002-01-01

Linear vestibular evoked potentials (VsEPs) measure the collective neural activity of the gravity receptor organs in the inner ear that respond to linear acceleration transients. The present study examined the effects of electrode placement, analog filtering, stimulus polarity and stimulus rate on linear VsEP thresholds, latencies and amplitudes recorded from mice. Two electrode-recording montages were evaluated, rostral (forebrain) to 'mastoid' and caudal (cerebellum) to 'mastoid'. VsEP thresholds and peak latencies were identical between the two recording sites; however, peak amplitudes were larger for the caudal recording montage. VsEPs were also affected by filtering. Results suggest optimum high pass filter cutoff at 100-300 Hz, and low pass filter cutoff at 10,000 Hz. To evaluate stimulus rate, linear jerk pulses were presented at 9.2, 16, 25, 40 and 80 Hz. At 80 Hz, mean latencies were longer (0.350-0.450 ms) and mean amplitudes reduced (0.8-1.8 microV) for all response peaks. In 50% of animals, late peaks (P3, N3) disappeared at 80 Hz. The results offer options for VsEP recording protocols. Copyright 2002 Elsevier Science B.V.

RESISTANCE TO EXTINCTION AND RELAPSE IN COMBINED STIMULUS CONTEXTS

PubMed Central

Podlesnik, Christopher A; Bai, John Y. H; Elliffe, Douglas

2012-01-01

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

Audio-visual synchrony and spatial attention enhance processing of dynamic visual stimulation independently and in parallel: A frequency-tagging study.

PubMed

Covic, Amra; Keitel, Christian; Porcu, Emanuele; Schröger, Erich; Müller, Matthias M

2017-11-01

The neural processing of a visual stimulus can be facilitated by attending to its position or by a co-occurring auditory tone. Using frequency-tagging, we investigated whether facilitation by spatial attention and audio-visual synchrony rely on similar neural processes. Participants attended to one of two flickering Gabor patches (14.17 and 17 Hz) located in opposite lower visual fields. Gabor patches further "pulsed" (i.e. showed smooth spatial frequency variations) at distinct rates (3.14 and 3.63 Hz). Frequency-modulating an auditory stimulus at the pulse-rate of one of the visual stimuli established audio-visual synchrony. Flicker and pulsed stimulation elicited stimulus-locked rhythmic electrophysiological brain responses that allowed tracking the neural processing of simultaneously presented Gabor patches. These steady-state responses (SSRs) were quantified in the spectral domain to examine visual stimulus processing under conditions of synchronous vs. asynchronous tone presentation and when respective stimulus positions were attended vs. unattended. Strikingly, unique patterns of effects on pulse- and flicker driven SSRs indicated that spatial attention and audiovisual synchrony facilitated early visual processing in parallel and via different cortical processes. We found attention effects to resemble the classical top-down gain effect facilitating both, flicker and pulse-driven SSRs. Audio-visual synchrony, in turn, only amplified synchrony-producing stimulus aspects (i.e. pulse-driven SSRs) possibly highlighting the role of temporally co-occurring sights and sounds in bottom-up multisensory integration. Copyright © 2017 Elsevier Inc. All rights reserved.

Extinction of likes and dislikes: effects of feature-specific attention allocation.

PubMed

Vanaelst, Jolien; Spruyt, Adriaan; Everaert, Tom; De Houwer, Jan

2017-12-01

The evaluative conditioning (EC) effect refers to the change in the liking of a neutral stimulus (conditioned stimulus, CS) due to its pairing with another stimulus (unconditioned stimulus, US). We examined whether the extinction rate of the EC effect is moderated by feature-specific attention allocation. In two experiments, CSs were abstract Gabor patches varying along two orthogonal, perceptual dimensions (i.e. spatial frequency and orientation). During the acquisition phase, one of these dimensions was predictive of the valence of the USs. During the extinction phase, CSs were presented alone and participants were asked to categorise the CSs either according to their valence, the perceptual dimension that was task-relevant during the acquisition phase, or a perceptual dimension that was task-irrelevant during the acquisition phase. As predicted, explicit valence measures revealed a linear increase in the extinction rate of the EC effect as participants were encouraged to assign attention to non-evaluative stimulus information during the extinction phase. In Experiment 1, Affect Misattribution Paradigm (AMP) data mimicked this pattern of results, although the effect just missed conventional levels of significance. In Experiment 2, the AMP data revealed an increase of the EC effect if attention was focused on evaluative stimulus information. Potential mechanisms to explain these findings are discussed.

The Effects of Auditory Tempo Changes on Rates of Stereotypic Behavior in Handicapped Children.

ERIC Educational Resources Information Center

Christopher, R.; Lewis, B.

1984-01-01

Rates of stereotypic behaviors in six severely/profoundly retarded children (eight to 15 years old) were observed during varying presentations of auditory beats produced by a metronome. Visual and statistical analysis of research results suggested a significant reaction to stimulus presentation. However, additional data following…

Causes of dissociation between subjective workload measures and performance - Caveats for the use of subjective assessments

NASA Technical Reports Server (NTRS)

Vidulich, M. A.; Wickens, C. D.

1985-01-01

Dissociations between subjective workload assessments and performance were investigated. The difficulty of a Sternberg memory search task was manipulated by varying stimulus presentation rate, stimulus discernibility, value of good performance, and automaticity of performance. All Sternberg task conditions were performed both alone and concurrently with a tracking task. Bipolar subjective workload assessments were collected. Dissociations between workload and performance were found related to automaticity, presentation rate, and motivation level. The results were interpreted as supporting the hypothesis that the specific cognitive processes responsible for subjective assessments can differ from those responsible for performance. The potential contamination these dissociations could inflict on operational workload assessments is discussed.

The Rate of Change of Vergence-Accommodation Conflict Affects Visual Discomfort

PubMed Central

Kane, David; Banks, Martin S.

2014-01-01

Stereoscopic (S3D) displays create conflicts between the distance to which the eyes must converge and the distance to which the eyes must accommodate. Such conflicts require the viewer to overcome the normal coupling between vergence and accommodation, and this effort appears to cause viewer discomfort. Vergence-accommodation coupling is driven by the phasic components of the underlying control systems, and those components respond to relatively fast changes in vergence and accommodative stimuli. Given the relationship between phasic changes and vergence-accommodation coupling, we examined how the rate of change in the vergence-accommodation conflict affects viewer discomfort. We used a stereoscopic display that allows independent manipulation of the stimuli to vergence and accommodation. We presented stimuli that simulate natural viewing (i.e., vergence and accommodative stimuli changed together) and stimuli that simulate S3D viewing (i.e., vergence stimulus changes but accommodative stimulus remains fixed). The changes occurred at 0.01, 0.05, or 0.25Hz. The lowest rate is too slow to stimulate the phasic components while the highest rate is well within the phasic range. The results were consistent with our expectation: somewhat greater discomfort was experienced when stimulus distance changed rapidly, particularly in S3D viewing when the vergence stimulus changed but the accommodative stimulus did not. These results may help in the generation of guidelines for the creation and viewing of stereo content with acceptable viewer comfort. PMID:25448713

The effects of prepulse-blink reflex trial repetition and prepulse change on blink reflex modification at short and long lead intervals.

PubMed

Lipp, O V; Siddle, D A

1998-01-01

Prepulse inhibition and facilitation of the blink reflex are said to reflect different responses elicited by the lead stimulus, transient detection and orienting response respectively. Two experiments investigated the effects of trial repetition and lead stimulus change on blink modification. It was hypothesized that these manipulations will affect orienting and thus blink facilitation to a greater extent than they will affect transient detection and thus blink inhibition. In Experiment 1 (N = 64), subjects were trained with a sequence of 12 lead stimulus and 12 blink stimulus alone presentations, and 24 lead stimulus-blink stimulus pairings. Lead interval was 120 ms for 12 of the trials and 2000 ms for the other 12. For half the subjects this sequence was followed by a change in pitch of the lead stimulus. In Experiment 2 (N = 64), subjects were trained with a sequence of 36 blink alone stimuli and 36 lead stimulus-blink stimulus pairings. The lead interval was 120 ms for half the subjects and 2000 ms for the other half. The pitch of the lead stimulus on prestimulus trials 31-33 was changed for half the subjects in each group. In both experiments, the amount of blink inhibition decreased during training whereas the amount of blink facilitation remained unchanged. Lead stimulus change had no effect on blink modification in either experiment although it resulted in enhanced skin conductance responses and greater heart rate deceleration in Experiment 2. The present results are not consistent with the notion that blink facilitation is linked to orienting whereas blink inhibition reflects a transient detection mechanism.

Hemispheric differences in visual search of simple line arrays.

PubMed

Polich, J; DeFrancesco, D P; Garon, J F; Cohen, W

1990-01-01

The effects of perceptual organization on hemispheric visual-information processing were assessed with stimulus arrays composed of short lines arranged in columns. A visual-search task was employed in which subjects judged whether all the lines were vertical (same) or whether a single horizontal line was present (different). Stimulus-display organization was manipulated in two experiments by variation of line density, linear organization, and array size. In general, left-visual-field/right-hemisphere presentations demonstrated more rapid and accurate responses when the display was perceived as a whole. Right-visual-field/left-hemisphere superiorities were observed when the display organization coerced assessment of individual array elements because the physical qualities of the stimulus did not effect a gestalt whole. Response times increased somewhat with increases in array size, although these effects interacted with other stimulus variables. Error rates tended to follow the reaction-time patterns. The results suggest that laterality differences in visual search are governed by stimulus properties which contribute to, or inhibit, the perception of a display as a gestalt. The implications of these findings for theoretical interpretations of hemispheric specialization are discussed.

Flavor Identification and Intensity: Effects of Stimulus Context

PubMed Central

Hallowell, Emily S.; Parikh, Roshan; Veldhuizen, Maria G.

2016-01-01

Two experiments presented oral mixtures containing different proportions of the gustatory flavorant sucrose and an olfactory flavorant, either citral (Experiment 1) or lemon (Experiment 2). In 4 different sessions of each experiment, subjects identified each mixture as “mostly sugar” or “mostly citrus/lemon” or rated the perceived intensities of the sweet and citrus components. Different sessions also presented the mixtures in different contexts, with mixtures containing relatively high concentrations of sucrose or citral/lemon presented more often (skew sucrose or skew citral/lemon). As expected, in both experiments, varying stimulus context affected both identification and perceived intensity: Skewing to sucrose versus citral/lemon decreased the probability of identifying the stimuli as “mostly sugar” and reduced the ratings of sweet intensity relative to citrus intensity. Across both contextual conditions of both experiments, flavor identification associated closely with the ratio of the perceived sweet and citrus intensities. The results accord with a model, extrapolated from signal-detection theory, in which sensory events are represented as multisensory–multidimensional distributions in perceptual space. Changing stimulus context can shift the locations of the distributions relative to response criteria, Decision rules guide judgments based on both sensory events and criteria, these rules not necessarily being identical in tasks of identification and intensity rating. PMID:26830499

Reduced Perceptual Exclusivity during Object and Grating Rivalry in Autism

PubMed Central

Freyberg, J.; Robertson, C.E.; Baron-Cohen, S.

2015-01-01

Background The dynamics of binocular rivalry may be a behavioural footprint of excitatory and inhibitory neural transmission in visual cortex. Given the presence of atypical visual features in Autism Spectrum Conditions (ASC), and evidence in support of the idea of an imbalance in excitatory/inhibitory neural transmission in ASC, we hypothesized that binocular rivalry might prove a simple behavioural marker of such a transmission imbalance in the autistic brain. In support of this hypothesis, we previously reported a slower rate of rivalry in ASC, driven by reduced perceptual exclusivity. Methods We tested whether atypical dynamics of binocular rivalry in ASC are specific to certain stimulus features. 53 participants (26 with ASC, matched for age, sex and IQ) participated in binocular rivalry experiments in which the dynamics of rivalry were measured at two levels of stimulus complexity, low (grayscale gratings) and high (coloured objects). Results Individuals with ASC experienced a slower rate of rivalry, driven by longer transitional states between dominant percepts. These exaggerated transitional states were present at both low and high levels of stimulus complexity, suggesting that atypical rivalry dynamics in autism are robust with respect to stimulus choice. Interactions between stimulus properties and rivalry dynamics in autism indicate that achromatic grating stimuli produce stronger group differences. Conclusion These results confirm the finding of atypical dynamics of binocular rivalry in ASC. These dynamics were present for stimuli of both low and high levels of visual complexity, suggesting an imbalance in competitive interactions throughout the visual system of individuals with ASC. PMID:26382002

Adaptation to stimulus statistics in the perception and neural representation of auditory space.

PubMed

Dahmen, Johannes C; Keating, Peter; Nodal, Fernando R; Schulz, Andreas L; King, Andrew J

2010-06-24

Sensory systems are known to adapt their coding strategies to the statistics of their environment, but little is still known about the perceptual implications of such adjustments. We investigated how auditory spatial processing adapts to stimulus statistics by presenting human listeners and anesthetized ferrets with noise sequences in which interaural level differences (ILD) rapidly fluctuated according to a Gaussian distribution. The mean of the distribution biased the perceived laterality of a subsequent stimulus, whereas the distribution's variance changed the listeners' spatial sensitivity. The responses of neurons in the inferior colliculus changed in line with these perceptual phenomena. Their ILD preference adjusted to match the stimulus distribution mean, resulting in large shifts in rate-ILD functions, while their gain adapted to the stimulus variance, producing pronounced changes in neural sensitivity. Our findings suggest that processing of auditory space is geared toward emphasizing relative spatial differences rather than the accurate representation of absolute position.

The integration of habits maintained by food and water reinforcement through stimulus compounding.

PubMed Central

Weiss, S J; Schindler, C W; Eason, R

1988-01-01

In Experiment 1, a light and a tone were correlated independently with water reinforcement of bar pressing by rats. With different naive subjects in Experiment 2, one of these stimuli was correlated with food and the other with water reinforcement (counterbalanced). In both experiments the absence of tone and light signaled extinction. Tests of stimulus-reinforcer independence in Experiment 2 indicated that tone and light controlled behavior whose rate was specifically affected by deprivation state. In the stimulus-compounding tests of both experiments, response rates were higher to tone-plus-light than to tone or light presented alone (additive summation). This is the first report of additive summation produced through compounding stimuli paired with different reinforcers. The results are discussed in the context of the effects of incentive motivation on operant performance. PMID:3193056

Behavioral determination of stimulus pair discrimination of auditory acoustic and electrical stimuli using a classical conditioning and heart-rate approach.

PubMed

Morgan, Simeon J; Paolini, Antonio G

2012-06-06

Acute animal preparations have been used in research prospectively investigating electrode designs and stimulation techniques for integration into neural auditory prostheses, such as auditory brainstem implants and auditory midbrain implants. While acute experiments can give initial insight to the effectiveness of the implant, testing the chronically implanted and awake animals provides the advantage of examining the psychophysical properties of the sensations induced using implanted devices. Several techniques such as reward-based operant conditioning, conditioned avoidance, or classical fear conditioning have been used to provide behavioral confirmation of detection of a relevant stimulus attribute. Selection of a technique involves balancing aspects including time efficiency (often poor in reward-based approaches), the ability to test a plurality of stimulus attributes simultaneously (limited in conditioned avoidance), and measure reliability of repeated stimuli (a potential constraint when physiological measures are employed). Here, a classical fear conditioning behavioral method is presented which may be used to simultaneously test both detection of a stimulus, and discrimination between two stimuli. Heart-rate is used as a measure of fear response, which reduces or eliminates the requirement for time-consuming video coding for freeze behaviour or other such measures (although such measures could be included to provide convergent evidence). Animals were conditioned using these techniques in three 2-hour conditioning sessions, each providing 48 stimulus trials. Subsequent 48-trial testing sessions were then used to test for detection of each stimulus in presented pairs, and test discrimination between the member stimuli of each pair. This behavioral method is presented in the context of its utilisation in auditory prosthetic research. The implantation of electrocardiogram telemetry devices is shown. Subsequent implantation of brain electrodes into the Cochlear Nucleus, guided by the monitoring of neural responses to acoustic stimuli, and the fixation of the electrode into place for chronic use is likewise shown.

Generalization of the disruptive effects of alternative stimuli when combined with target stimuli in extinction.

PubMed

Podlesnik, Christopher A; Miranda-Dukoski, Ludmila; Jonas Chan, C K; Bland, Vikki J; Bai, John Y H

2017-09-01

Differential-reinforcement treatments reduce target problem behavior in the short term but at the expense of making it more persistent long term. Basic and translational research based on behavioral momentum theory suggests that combining features of stimuli governing an alternative response with the stimuli governing target responding could make target responding less persistent. However, changes to the alternative stimulus context when combining alternative and target stimuli could diminish the effectiveness of the alternative stimulus in reducing target responding. In an animal model with pigeons, the present study reinforced responding in the presence of target and alternative stimuli. When combining the alternative and target stimuli during extinction, we altered the alternative stimulus through changes in line orientation. We found that (1) combining alternative and target stimuli in extinction more effectively decreased target responding than presenting the target stimulus on its own; (2) combining these stimuli was more effective in decreasing target responding trained with lower reinforcement rates; and (3) changing the alternative stimulus reduced its effectiveness when it was combined with the target stimulus. Therefore, changing alternative stimuli (e.g., therapist, clinical setting) during behavioral treatments that combine alternative and target stimuli could reduce the effectiveness of those treatments in disrupting problem behavior. © 2017 Society for the Experimental Analysis of Behavior.

Integration of auditory and vibrotactile stimuli: Effects of frequency

PubMed Central

Wilson, E. Courtenay; Reed, Charlotte M.; Braida, Louis D.

2010-01-01

Perceptual integration of vibrotactile and auditory sinusoidal tone pulses was studied in detection experiments as a function of stimulation frequency. Vibrotactile stimuli were delivered through a single channel vibrator to the left middle fingertip. Auditory stimuli were presented diotically through headphones in a background of 50 dB sound pressure level broadband noise. Detection performance for combined auditory-tactile presentations was measured using stimulus levels that yielded 63% to 77% correct unimodal performance. In Experiment 1, the vibrotactile stimulus was 250 Hz and the auditory stimulus varied between 125 and 2000 Hz. In Experiment 2, the auditory stimulus was 250 Hz and the tactile stimulus varied between 50 and 400 Hz. In Experiment 3, the auditory and tactile stimuli were always equal in frequency and ranged from 50 to 400 Hz. The highest rates of detection for the combined-modality stimulus were obtained when stimulating frequencies in the two modalities were equal or closely spaced (and within the Pacinian range). Combined-modality detection for closely spaced frequencies was generally consistent with an algebraic sum model of perceptual integration; wider-frequency spacings were generally better fit by a Pythagorean sum model. Thus, perceptual integration of auditory and tactile stimuli at near-threshold levels appears to depend both on absolute frequency and relative frequency of stimulation within each modality. PMID:21117754

Least-squares (LS) deconvolution of a series of overlapping cortical auditory evoked potentials: a simulation and experimental study

NASA Astrophysics Data System (ADS)

Bardy, Fabrice; Van Dun, Bram; Dillon, Harvey; Cowan, Robert

2014-08-01

Objective. To evaluate the viability of disentangling a series of overlapping ‘cortical auditory evoked potentials’ (CAEPs) elicited by different stimuli using least-squares (LS) deconvolution, and to assess the adaptation of CAEPs for different stimulus onset-asynchronies (SOAs). Approach. Optimal aperiodic stimulus sequences were designed by controlling the condition number of matrices associated with the LS deconvolution technique. First, theoretical considerations of LS deconvolution were assessed in simulations in which multiple artificial overlapping responses were recovered. Second, biological CAEPs were recorded in response to continuously repeated stimulus trains containing six different tone-bursts with frequencies 8, 4, 2, 1, 0.5, 0.25 kHz separated by SOAs jittered around 150 (120-185), 250 (220-285) and 650 (620-685) ms. The control condition had a fixed SOA of 1175 ms. In a second condition, using the same SOAs, trains of six stimuli were separated by a silence gap of 1600 ms. Twenty-four adults with normal hearing (<20 dB HL) were assessed. Main results. Results showed disentangling of a series of overlapping responses using LS deconvolution on simulated waveforms as well as on real EEG data. The use of rapid presentation and LS deconvolution did not however, allow the recovered CAEPs to have a higher signal-to-noise ratio than for slowly presented stimuli. The LS deconvolution technique enables the analysis of a series of overlapping responses in EEG. Significance. LS deconvolution is a useful technique for the study of adaptation mechanisms of CAEPs for closely spaced stimuli whose characteristics change from stimulus to stimulus. High-rate presentation is necessary to develop an understanding of how the auditory system encodes natural speech or other intrinsically high-rate stimuli.

Discriminative-stimulus effects of zolpidem, triazolam, pentobarbital, and caffeine in zolpidem-trained humans.

PubMed

Rush, C R; Baker, R W; Rowlett, J K

2000-02-01

Six non-drug-abusing humans were trained to discriminate 15 mg zolpidem in the present experiment. After participants acquired discrimination, a range of doses of zolpidem (2.5-15.0 mg), triazolam (0.0625-0.3750 mg), pentobarbital (25-150 mg), caffeine (100-600 mg), and placebo were tested to determine whether they shared discriminative-stimulus effects with 15 mg zolpidem. The participant-rated and performance-impairing effects of zolpidem, triazolam, pentobarbital, and caffeine were assessed concurrently. Triazolam and pentobarbital dose dependently increased zolpidem-appropriate responding. Caffeine occasioned low levels of zolpidem-appropriate responding. Zolpidem, triazolam, and pentobarbital, but not caffeine, generally produced a similar constellation of participant-rated drug effects (e.g., increased scores for the Pentobarbital, Chlorpromazine, and Alcohol Group subscale on the Addiction Research Center Inventory) and dose dependently impaired performance. These results suggest that humans can reliably discriminate zolpidem. Despite its unique benzodiazepine-receptor binding profile, the discriminative-stimulus, participant-rated, and performance-impairing effects of zolpidem are similar to those of the barbiturates and benzodiazepines.

Neurons in the pigeon caudolateral nidopallium differentiate Pavlovian conditioned stimuli but not their associated reward value in a sign-tracking paradigm

PubMed Central

Kasties, Nils; Starosta, Sarah; Güntürkün, Onur; Stüttgen, Maik C.

2016-01-01

Animals exploit visual information to identify objects, form stimulus-reward associations, and prepare appropriate behavioral responses. The nidopallium caudolaterale (NCL), an associative region of the avian endbrain, contains neurons exhibiting prominent response modulation during presentation of reward-predicting visual stimuli, but it is unclear whether neural activity represents valuation signals, stimulus properties, or sensorimotor contingencies. To test the hypothesis that NCL neurons represent stimulus value, we subjected pigeons to a Pavlovian sign-tracking paradigm in which visual cues predicted rewards differing in magnitude (large vs. small) and delay to presentation (short vs. long). Subjects’ strength of conditioned responding to visual cues reliably differentiated between predicted reward types and thus indexed valuation. The majority of NCL neurons discriminated between visual cues, with discriminability peaking shortly after stimulus onset and being maintained at lower levels throughout the stimulus presentation period. However, while some cells’ firing rates correlated with reward value, such neurons were not more frequent than expected by chance. Instead, neurons formed discernible clusters which differed in their preferred visual cue. We propose that this activity pattern constitutes a prerequisite for using visual information in more complex situations e.g. requiring value-based choices. PMID:27762287

Stimulus driver for epilepsy seizure suppression with adaptive loading impedance

NASA Astrophysics Data System (ADS)

Ker, Ming-Dou; Lin, Chun-Yu; Chen, Wei-Ling

2011-10-01

A stimulus driver circuit for a micro-stimulator used in an implantable device is presented in this paper. For epileptic seizure control, the target of the driver was to output 30 µA stimulus currents when the electrode impedance varied between 20 and 200 kΩ. The driver, which consisted of the output stage, control block and adaptor, was integrated in a single chip. The averaged power consumption of the stimulus driver was 0.24-0.56 mW at 800 Hz stimulation rate. Fabricated in a 0.35 µm 3.3 V/24 V CMOS process and applied to a closed-loop epileptic seizure monitoring and controlling system, the proposed design has been successfully verified in the experimental results of Long-Evans rats with epileptic seizures.

Effects of acoustic noise on the auditory nerve compound action potentials evoked by electric pulse trains.

PubMed

Nourski, Kirill V; Abbas, Paul J; Miller, Charles A; Robinson, Barbara K; Jeng, Fuh-Cherng

2005-04-01

This study investigated the effects of acoustic noise on the auditory nerve compound action potentials in response to electric pulse trains. Subjects were adult guinea pigs, implanted with a minimally invasive electrode to preserve acoustic sensitivity. Electrically evoked compound action potentials (ECAP) were recorded from the auditory nerve trunk in response to electric pulse trains both during and after the presentation of acoustic white noise. Simultaneously presented acoustic noise produced a decrease in ECAP amplitude. The effect of the acoustic masker on the electric probe was greatest at the onset of the acoustic stimulus and it was followed by a partial recovery of the ECAP amplitude. Following cessation of the acoustic noise, ECAP amplitude recovered over a period of approximately 100-200 ms. The effects of the acoustic noise were more prominent at lower electric pulse rates (interpulse intervals of 3 ms and higher). At higher pulse rates, the ECAP adaptation to the electric pulse train alone was larger and the acoustic noise, when presented, produced little additional effect. The observed effects of noise on ECAP were the greatest at high electric stimulus levels and, for a particular electric stimulus level, at high acoustic noise levels.

Using stimulus shaping and fading to establish stimulus control in normal and retarded children.

PubMed

Smeets, P M; Lancioni, G E; Hoogeveen, F R

1984-09-01

The present study was an effort to investigate whether, in addition to his IQ level, the child's ability to identify all relevant stimulus components would affect the frequency of overselective responding. Children of different IQ levels (i.e. normal, educably retarded, and trainable retarded children) participated. Subjects were trained to learn the meanings of four sets of fictitious words, i.e. two sets containing words printed in Roman letters (Roman words), and two sets containing words printed in Hebrew letters (Hebrew words). All subjects could identify the words of each set. The normal and educably retarded subjects could read aloud the Roman words, whereas the trainable retarded subjects could not. None of the subjects could read the Hebrew words. Two training procedures were used, one requiring transfer of stimulus control (fading), and one which did not (stimulus shaping). The results indicated that, firstly, the discrimination learning of the normal and educably retarded subjects covaried with the IQ level and their ability to read the words. The learning rate was not affected by the training procedures. Secondly, the trainable retarded subjects learned much better through stimulus shaping than through fading. Their acquisition rates were slow and not affected by the types of letters. Thirdly, the training procedures had no effect on the breadth of stimulus control. Instead, it covaried as a function of the IQ level (all groups) and of the child's ability to read the words (normal and educably retarded subjects). Fourthly, the training procedures had, however, considerable effect on which letters controlled the discriminations. When overselective selective responding was evident, the letters that had been associated with the prompts were more often functional than the other letters, but only for the words trained through stimulus shaping.

On the respective contributions of awareness of unconditioned stimulus valence and unconditioned stimulus identity in attitude formation through evaluative conditioning.

PubMed

Stahl, Christoph; Unkelbach, Christian; Corneille, Olivier

2009-09-01

Evaluative conditioning (EC) is a central mechanism for both classic and current theories of attitude formation. In contrast to Pavlovian conditioning, it is often conceptualized as a form of evaluative learning that occurs without awareness of the conditioned stimulus-unconditioned stimulus (CS-US) contingencies. In the present research, the authors directly address this point by assessing the respective roles of US valence awareness and US identity awareness in attitude formation through EC. Across 4 experiments, EC was assessed with evaluative ratings as well as evaluative priming measures, and the impact of valence and identity awareness on EC was evaluated. EC effects on priming and rating measures occurred only for CSs for which participants could report the associated US valence, and US identity awareness did not further contribute to EC. This finding was obtained both for semantically meaningless (i.e., nonword letter sequences) and meaningful (i.e., consumer products) CSs. These results provide further support for the critical role of contingency awareness in EC, albeit valence awareness, not identity awareness. (c) 2009 APA, all rights reserved).

Effects of interstimulus intervals on behavioral, heart rate, and event-related potential indices of infant engagement and sustained attention

PubMed Central

Xie, Wanze; Richards, John E.

2016-01-01

Maximizing infant attention to stimulus presentation during an EEG or ERP experiment is important for making valid inferences about the neural correlates of infant cognition. The present study examined the effects of stimulus presentation interstimulus interval (ISI) on behavioral and physiological indices of infant attention including infants’ fixation to visual presentation, the amount of heart rate (HR) change during sustained attention, and ERP components. This study compared an ISI that is typically used in infant EEG/ERP studies (e.g., 1,500–2,000 ms) with two shorter durations (400–600 ms and 600–1,000 ms). Thirty-six infants were tested cross-sectionally at 3, 4.5, and 6 months. It was found that using the short (400–600 ms) and medium (600–1,000 ms) ISIs resulted in more visually fixated trials and reduced frequency of fixation disengagement per experimental block. We also found larger HR changes during sustained attention to both of the shorter ISIs compared with the long ISI, and larger ERP responses when using the medium ISI compared to using the short and long ISIs. These data suggest that utilizing an optimal ISI (e.g., 600– 1,000 ms), which increases the presentation complexity and provides sufficient time for information processing, can promote infant engagement and sustained attention during stimulus presentation. PMID:27159263

Conditioned pain modulation is minimally influenced by cognitive evaluation or imagery of the conditioning stimulus

PubMed Central

Bernaba, Mario; Johnson, Kevin A; Kong, Jiang-Ti; Mackey, Sean

2014-01-01

Purpose Conditioned pain modulation (CPM) is an experimental approach for probing endogenous analgesia by which one painful stimulus (the conditioning stimulus) may inhibit the perceived pain of a subsequent stimulus (the test stimulus). Animal studies suggest that CPM is mediated by a spino–bulbo–spinal loop using objective measures such as neuronal firing. In humans, pain ratings are often used as the end point. Because pain self-reports are subject to cognitive influences, we tested whether cognitive factors would impact on CPM results in healthy humans. Methods We conducted a within-subject, crossover study of healthy adults to determine the extent to which CPM is affected by 1) threatening and reassuring evaluation and 2) imagery alone of a cold conditioning stimulus. We used a heat stimulus individualized to 5/10 on a visual analog scale as the testing stimulus and computed the magnitude of CPM by subtracting the postconditioning rating from the baseline pain rating of the heat stimulus. Results We found that although evaluation can increase the pain rating of the conditioning stimulus, it did not significantly alter the magnitude of CPM. We also found that imagery of cold pain alone did not result in statistically significant CPM effect. Conclusion Our results suggest that CPM is primarily dependent on sensory input, and that the cortical processes of evaluation and imagery have little impact on CPM. These findings lend support for CPM as a useful tool for probing endogenous analgesia through subcortical mechanisms. PMID:25473310

Aging effects on functional auditory and visual processing using fMRI with variable sensory loading.

PubMed

Cliff, Michael; Joyce, Dan W; Lamar, Melissa; Dannhauser, Thomas; Tracy, Derek K; Shergill, Sukhwinder S

2013-05-01

Traditionally, studies investigating the functional implications of age-related structural brain alterations have focused on higher cognitive processes; by increasing stimulus load, these studies assess behavioral and neurophysiological performance. In order to understand age-related changes in these higher cognitive processes, it is crucial to examine changes in visual and auditory processes that are the gateways to higher cognitive functions. This study provides evidence for age-related functional decline in visual and auditory processing, and regional alterations in functional brain processing, using non-invasive neuroimaging. Using functional magnetic resonance imaging (fMRI), younger (n=11; mean age=31) and older (n=10; mean age=68) adults were imaged while observing flashing checkerboard images (passive visual stimuli) and hearing word lists (passive auditory stimuli) across varying stimuli presentation rates. Younger adults showed greater overall levels of temporal and occipital cortical activation than older adults for both auditory and visual stimuli. The relative change in activity as a function of stimulus presentation rate showed differences between young and older participants. In visual cortex, the older group showed a decrease in fMRI blood oxygen level dependent (BOLD) signal magnitude as stimulus frequency increased, whereas the younger group showed a linear increase. In auditory cortex, the younger group showed a relative increase as a function of word presentation rate, while older participants showed a relatively stable magnitude of fMRI BOLD response across all rates. When analyzing participants across all ages, only the auditory cortical activation showed a continuous, monotonically decreasing BOLD signal magnitude as a function of age. Our preliminary findings show an age-related decline in demand-related, passive early sensory processing. As stimulus demand increases, visual and auditory cortex do not show increases in activity in older compared to younger people. This may negatively impact on the fidelity of information available to higher cognitive processing. Such evidence may inform future studies focused on cognitive decline in aging. Copyright © 2012 Elsevier Ltd. All rights reserved.

Extended lowered body temperature increases the effective CS-US interval in conditioned taste aversion for adult rats.

PubMed

Hinderliter, Charles F; Goodhart, Mark; Anderson, Matthew J; Misanin, James R

2002-06-01

Assuming body temperature correlates with metabolic activities, rate of body temperature recovery was manipulated to assess effects on long-trace conditioning in a conditioned taste-aversion paradigm. Following 10 min. access to a .1% saccharin solution and then 10 min. immersion in 0-0.5 degrees C water, two groups of 16 Wistar-derived, 81-113 day-old, male albino rats received either saline or lithium chloride injections 3 hr. later. These two groups were subdivided on basis of warming rate during the 3-hr. interval. Half of the rats recovered at room temperature (20 degrees to 21 degrees C), and half recovered in an incubator maintained at 30 degrees C. Maintaining a lowered body temperature between the conditioned stimulus and unconditioned stimulus allowed an association to be made at 3 hr., an interval that normally does not support conditioning. In contrast, lowering body temperature and then inducing a fast warming rate did not produce evidence of an aversion. It is suggested that maintaining a low body temperature over the interval between the presentation of the conditioned stimulus and unconditioned stimulus slows a metabolic clock that extends the measured interval at which associations can be made using conditioned taste-aversion procedures.

Resistance to Change and Frequency of Response-Dependent Stimuli Uncorrelated with Reinforcement

ERIC Educational Resources Information Center

Podlesnik, Christopher A.; Jimenez-Gomez, Corina; Ward, Ryan D.; Shahan, Timothy A.

2009-01-01

Stimuli uncorrelated with reinforcement have been shown to enhance response rates and resistance to disruption; however, the effects of different rates of stimulus presentations have not been assessed. In two experiments, we assessed the effects of adding different rates of response-dependent brief stimuli uncorrelated with primary reinforcement…

Dynamic afferent synapses to decision-making networks improve performance in tasks requiring stimulus associations and discriminations

PubMed Central

Bourjaily, Mark A.

2012-01-01

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. PMID:22457467

Expectancy bias in a selective conditioning procedure: trait anxiety increases the threat value of a blocked stimulus.

PubMed

Boddez, Yannick; Vervliet, Bram; Baeyens, Frank; Lauwers, Stephanie; Hermans, Dirk; Beckers, Tom

2012-06-01

In a blocking procedure, a single conditioned stimulus (CS) is paired with an unconditioned stimulus (US), such as electric shock, in the first stage. During the subsequent stage, the CS is presented together with a second CS and this compound is followed by the same US. Fear conditioning studies in non-human animals have demonstrated that fear responding to the added second CS typically remains low, despite its being paired with the US. Accordingly, the blocking procedure is well suited as a laboratory model for studying (deficits in) selective threat appraisal. The present study tested the relation between trait anxiety and blocking in human aversive conditioning. Healthy participants filled in a trait anxiety questionnaire and underwent blocking treatment in the human aversive conditioning paradigm. Threat appraisal was measured through shock expectancy ratings and skin conductance. As hypothesized, trait anxiety was positively associated with shock expectancy ratings to the blocked stimulus. In skin conductance responding, no significant effects of stimulus type could be detected during blocking training or testing. The current study does not allow strong claims to be made regarding the theoretical process underlying the expectancy bias we observed. The observed shock expectancy bias might be one of the mechanisms leading to non-specific fear in individuals at risk for developing anxiety disorders. A deficit in blocking, or a deficit in selective threat appraisal at the more general level, indeed results in fear becoming non-specific and disconnected from the most likely causes or predictors of danger. Copyright © 2011 Elsevier Ltd. All rights reserved.

Signaling added response-independent reinforcement to assess Pavlovian processes in resistance to change and relapse.

PubMed

Podlesnik, Christopher A; Fleet, James D

2014-09-01

Behavioral momentum theory asserts Pavlovian stimulus-reinforcer relations govern the persistence of operant behavior. Specifically, resistance to conditions of disruption (e.g., extinction, satiation) reflects the relation between discriminative stimuli and the prevailing reinforcement conditions. The present study assessed whether Pavlovian stimulus-reinforcer relations govern resistance to disruption in pigeons by arranging both response-dependent and -independent food reinforcers in two components of a multiple schedule. In one component, discrete-stimulus changes preceded response-independent reinforcers, paralleling methods that reduce Pavlovian conditioned responding to contextual stimuli. Compared to the control component with no added stimuli preceding response-independent reinforcement, response rates increased as discrete-stimulus duration increased (0, 5, 10, and 15 s) across conditions. Although resistance to extinction decreased as stimulus duration increased in the component with the added discrete stimulus, further tests revealed no effect of discrete stimuli, including other disrupters (presession food, intercomponent food, modified extinction) and reinstatement designed to control for generalization decrement. These findings call into question a straightforward conception that the stimulus-reinforcer relations governing resistance to disruption reflect the same processes as Pavlovian conditioning, as asserted by behavioral momentum theory. © Society for the Experimental Analysis of Behavior.

Short-Term Memory; An Annotated Bibliography.

ERIC Educational Resources Information Center

Reynolds, Donald; Rosenblatt, Richard D.

This annotated bibliography on memory is divided into 12 areas: information theory; proactive and retroactive interference and interpolated activities; set, subject strategies, and coding techniques; paired associate studies; simultaneous listening and memory span studies; rate and mode of stimulus presentation; rate and order of recall, and…

An evaluation of multiple-schedule variations to reduce high-rate requests in the picture exchange communication system.

PubMed

Landa, Robin; Hanley, Gregory P

2016-06-01

Using procedures similar to those of Tiger, Hanley, and Heal (2006), we compared two multiple-schedule variations (S+/S- and S+ only) to treat high-rate requests for edible items in the Picture Exchange Communication System (PECS). Two individuals with autism participated, after they showed persistent requests for edible items after PECS training. Stimulus control was achieved only with the multiple schedule that involved presentation of a discriminative stimulus during reinforcement components and its removal during extinction components (S+ only). Discriminated requests were maintained for the 1 participant who experienced schedule thinning. © 2016 Society for the Experimental Analysis of Behavior.

Training methods for horses: habituation to a frightening stimulus.

PubMed

Christensen, J W; Rundgren, M; Olsson, K

2006-09-01

Responses of horses in frightening situations are important for both equine and human safety. Considerable scientific interest has been shown in development of reactivity tests, but little effort has been dedicated to the development of appropriate training methods for reducing fearfulness. To investigate which of 3 different training methods (habituation, desensitisation and counter-conditioning) was most effective in teaching horses to react calmly in a potentially frightening situation. 1) Horses are able to generalise about the test stimulus such that, once familiar with the test stimulus in one situation, it appears less frightening and elicits a reduced response even when the stimulus intensity is increased or the stimulus is presented differently; and 2) alternative methods such as desensitisation and counter-conditioning would be more efficient than a classic habituation approach. Twenty-seven naive 2-year-old Danish Warmblood stallions were trained according to 3 different methods, based on classical learning theory: 1) horses (n = 9) were exposed to the full stimulus (a moving, white nylon bag, 1.2 x 0.75 m) in 5 daily training sessions until they met a predefined habituation criterion (habituation); 2) horses (n = 9) were introduced gradually to the stimulus and habituated to each step before the full stimulus was applied (desensitisation); 3) horses (n = 9) were trained to associate the stimulus with a positive reward before being exposed to the full stimulus (counter-conditioning). Each horse received 5 training sessions of 3 min per day. Heart rate and behavioural responses were recorded. Horses trained with the desensitisation method showed fewer flight responses in total and needed fewer training sessions to learn to react calmly to test stimuli. Variations in heart rate persisted even when behavioural responses had ceased. In addition, all horses on the desensitisation method eventually habituated to the test stimulus whereas some horses on the other methods did not. Desensitisation appeared to be the most effective training method for horses in frightening situations. Further research is needed in order to investigate the role of positive reinforcement, such as offering food, in the training of horses.

Metastable neural dynamics mediates expectation

NASA Astrophysics Data System (ADS)

Mazzucato, Luca; La Camera, Giancarlo; Fontanini, Alfredo

Sensory stimuli are processed faster when their presentation is expected compared to when they come as a surprise. We previously showed that, in multiple single-unit recordings from alert rat gustatory cortex, taste stimuli can be decoded faster from neural activity if preceded by a stimulus-predicting cue. However, the specific computational process mediating this anticipatory neural activity is unknown. Here, we propose a biologically plausible model based on a recurrent network of spiking neurons with clustered architecture. In the absence of stimulation, the model neural activity unfolds through sequences of metastable states, each state being a population vector of firing rates. We modeled taste stimuli and cue (the same for all stimuli) as two inputs targeting subsets of excitatory neurons. As observed in experiment, stimuli evoked specific state sequences, characterized in terms of `coding states', i.e., states occurring significantly more often for a particular stimulus. When stimulus presentation is preceded by a cue, coding states show a faster and more reliable onset, and expected stimuli can be decoded more quickly than unexpected ones. This anticipatory effect is unrelated to changes of firing rates in stimulus-selective neurons and is absent in homogeneous balanced networks, suggesting that a clustered organization is necessary to mediate the expectation of relevant events. Our results demonstrate a novel mechanism for speeding up sensory coding in cortical circuits. NIDCD K25-DC013557 (LM); NIDCD R01-DC010389 (AF); NSF IIS-1161852 (GL).

Masking reduces orientation selectivity in rat visual cortex

PubMed Central

Alwis, Dasuni S.; Richards, Katrina L.

2016-01-01

In visual masking the perception of a target stimulus is impaired by a preceding (forward) or succeeding (backward) mask stimulus. The illusion is of interest because it allows uncoupling of the physical stimulus, its neuronal representation, and its perception. To understand the neuronal correlates of masking, we examined how masks affected the neuronal responses to oriented target stimuli in the primary visual cortex (V1) of anesthetized rats (n = 37). Target stimuli were circular gratings with 12 orientations; mask stimuli were plaids created as a binarized sum of all possible target orientations. Spatially, masks were presented either overlapping or surrounding the target. Temporally, targets and masks were presented for 33 ms, but the stimulus onset asynchrony (SOA) of their relative appearance was varied. For the first time, we examine how spatially overlapping and center-surround masking affect orientation discriminability (rather than visibility) in V1. Regardless of the spatial or temporal arrangement of stimuli, the greatest reductions in firing rate and orientation selectivity occurred for the shortest SOAs. Interestingly, analyses conducted separately for transient and sustained target response components showed that changes in orientation selectivity do not always coincide with changes in firing rate. Given the near-instantaneous reductions observed in orientation selectivity even when target and mask do not spatially overlap, we suggest that monotonic visual masking is explained by a combination of neural integration and lateral inhibition. PMID:27535373

Bidirectional Telemetry Controller for Neuroprosthetic Devices

PubMed Central

Sharma, Vishnu; McCreery, Douglas B.; Han, Martin; Pikov, Victor

2010-01-01

We present versatile multifunctional programmable controller with bidirectional data telemetry, implemented using existing commercial microchips and standard Bluetooth protocol, which adds convenience, reliability, and ease-of-use to neuroprosthetic devices. Controller, weighing 190 g, is placed on animal's back and provides bidirectional sustained telemetry rate of 500 kb/s, allowing real-time control of stimulation parameters and viewing of acquired data. In continuously-active state, controller consumes ∼420 mW and operates without recharge for 8 h. It features independent 16-channel current-controlled stimulation, allowing current steering; customizable stimulus current waveforms; recording of stimulus voltage waveforms and evoked neuronal responses with stimulus artifact blanking circuitry. Flexibility, scalability, cost-efficiency, and a user-friendly computer interface of this device allow use in animal testing for variety of neuroprosthetic applications. Initial testing of the controller has been done in a feline model of brainstem auditory prosthesis. In this model, the electrical stimulation is applied to the array of microelectrodes implanted in the ventral cochlear nucleus, while the evoked neuronal activity was recorded with the electrode implanted in the contralateral inferior colliculus. Stimulus voltage waveforms to monitor the access impedance of the electrodes were acquired at the rate of 312 kilosamples/s. Evoked neuronal activity in the inferior colliculus was recorded after the blanking (transient silencing) of the recording amplifier during the stimulus pulse, allowing the detection of neuronal responses within 100 μs after the end of the stimulus pulse applied in the cochlear nucleus. PMID:19933010

Habituation contributes to the decline in wheel running within wheel-running reinforcement periods.

PubMed

Belke, Terry W; McLaughlin, Ryan J

2005-02-28

Habituation appears to play a role in the decline in wheel running within an interval. Aoyama and McSweeney [Aoyama, K., McSweeney, F.K., 2001. Habituation contributes to within-session changes in free wheel running. J. Exp. Anal. Behav. 76, 289-302] showed that when a novel stimulus was presented during a 30-min interval, wheel-running rates following the stimulus increased to levels approximating those earlier in the interval. The present study sought to assess the role of habituation in the decline in running that occurs over a briefer interval. In two experiments, rats responded on fixed-interval 30-s schedules for the opportunity to run for 45 s. Forty reinforcers were completed in each session. In the first experiment, the brake and chamber lights were repeatedly activated and inactivated after 25 s of a reinforcement interval had elapsed to assess the effect on running within the remaining 20 s. Presentations of the brake/light stimulus occurred during nine randomly determined reinforcement intervals in a session. In the second experiment, a 110 dB tone was emitted after 25 s of the reinforcement interval. In both experiments, presentation of the stimulus produced an immediate decline in running that dissipated over sessions. No increase in running following the stimulus was observed in the first experiment until the stimulus-induced decline dissipated. In the second experiment, increases in running were observed following the tone in the first session as well as when data were averaged over several sessions. In general, the results concur with the assertion that habituation plays a role in the decline in wheel running that occurs within both long and short intervals. (c) 2004 Elsevier B.V. All rights reserved.

Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location.

PubMed

Crago, Patrick E; Makowski, Nathaniel S

2014-10-01

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. 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. 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. 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 interventions involving motor or sensory stimulation.

The contribution of perceptual factors and training on varying audiovisual integration capacity.

PubMed

Wilbiks, Jonathan M P; Dyson, Benjamin J

2018-06-01

The suggestion that the capacity of audiovisual integration has an upper limit of 1 was challenged in 4 experiments using perceptual factors and training to enhance the binding of auditory and visual information. Participants were required to note a number of specific visual dot locations that changed in polarity when a critical auditory stimulus was presented, under relatively fast (200-ms stimulus onset asynchrony [SOA]) and slow (700-ms SOA) rates of presentation. In Experiment 1, transient cross-modal congruency between the brightness of polarity change and pitch of the auditory tone was manipulated. In Experiment 2, sustained chunking was enabled on certain trials by connecting varying dot locations with vertices. In Experiment 3, training was employed to determine if capacity would increase through repeated experience with an intermediate presentation rate (450 ms). Estimates of audiovisual integration capacity (K) were larger than 1 during cross-modal congruency at slow presentation rates (Experiment 1), during perceptual chunking at slow and fast presentation rates (Experiment 2), and, during an intermediate presentation rate posttraining (Experiment 3). Finally, Experiment 4 showed a linear increase in K using SOAs ranging from 100 to 600 ms, suggestive of quantitative rather than qualitative changes in the mechanisms in audiovisual integration as a function of presentation rate. The data compromise the suggestion that the capacity of audiovisual integration is limited to 1 and suggest that the ability to bind sounds to sights is contingent on individual and environmental factors. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The content of compound conditioning.

PubMed

Harris, Justin A; Andrew, Benjamin J; Livesey, Evan J

2012-04-01

In three experiments using Pavlovian conditioning of magazine approach, rats were trained with a compound stimulus, AB, and were concurrently trained with stimulus B on its own. The reinforcement rate of B, rB, was either 1/2, 2/3, or 2/5 of rAB. After extended training, the conditioning strength of A was assessed using probe trials in which A was presented alone. Responding during A was compared with that during AB, B, and a third stimulus, C, for which rC = rAB - rB. In each experiment, the rats' response rate during A was almost identical to that during C (and during B, when rB = 1/2rAB). This suggests that, during AB conditioning, the rats had learned about rA as being equal to [rAB - rB], and implies that the content of their learning was a linear function of r. The findings provide strong support for rate-based models of conditioning (e.g., Gallistel & Gibbon, 2000). They are also consistent with the associative account of learning defined in the Rescorla and Wagner (1972) model, but only if the learning rate during reinforcement equals that during nonreinforcement. (c) 2012 APA, all rights reserved.

The Effects of Televised Political Advertisements on Voter Perceptions about Candidates.

ERIC Educational Resources Information Center

Baskin, Otis Wayne

This study investigated whether candidate images could be designated as primarily either stimulus- or perceiver-determined and if a multiple regression model could be constructed to predict candidate image ratings from pre-stimulus perceptions of the candidate's party and post-stimulus ratings of the advertisement. One hundred twenty subjects were…

Stimulus Variables and Interpersonal Attraction: The Stimulus Context.

ERIC Educational Resources Information Center

Griffitt, William

In interpersonal attraction, studies and judgment research evaluation of a stimulus is often a function of the context within which the stimulus appears. The first experiment was designed to examine "contrast effects" (shifts in the rated value of a stimulus away from the contextual values) when all attitudinal information was received from two…

The Honolulu posttraumatic stress disorder stimulus set.

PubMed

Chemtob, C M; Roitblat, H L; Hamada, R S; Carlson, J G; Muraoka, M Y; Bauer, G B

1997-04-01

We present word and picture stimuli constituting a validated stimulus set appropriate for cognitive investigations of posttraumatic stress disorder (PTSD). Combat related and neutral words and pictures were rated by Vietnam veterans with PTSD and by three comparison groups along four dimensions: unpleasantness, Vietnam relevance, stressfulness, and memorability. There were distinctive patterns of responses by the PTSD group which efficiently discriminated the individuals in this group from those in the control groups. These stimuli have the potential to be developed as a diagnostic instrument.

Verbal instructions targeting valence alter negative conditional stimulus evaluations (but do not affect reinstatement rates).

PubMed

Luck, Camilla C; Lipp, Ottmar V

2018-02-01

Negative conditional stimulus (CS) valence acquired during fear conditioning may enhance fear relapse and is difficult to remove as it extinguishes slowly and does not respond to the instruction that unconditional stimulus (US) presentations will cease. We examined whether instructions targeting CS valence would be more effective. In Experiment 1, an image of one person (CS+) was paired with an aversive US, while another (CS-) was presented alone. After acquisition, participants were given positive information about the CS+ poser and negative information about the CS- poser. Instructions reversed the pattern of differential CS valence present during acquisition and eliminated differential electrodermal responding. In Experiment 2, we compared positive and negative CS revaluation by providing positive/negative information about the CS+ and neutral information about CS-. After positive revaluation, differential valence was removed and differential electrodermal responding remained intact. After negative revaluation, differential valence was strengthened and differential electrodermal responding was eliminated. Unexpectedly, the instructions did not affect the reinstatement of differential electrodermal responding.

[Allocation of attentional resource and monitoring processes under rapid serial visual presentation].

PubMed

Nishiura, K

1998-08-01

With the use of rapid serial visual presentation (RSVP), the present study investigated the cause of target intrusion errors and functioning of monitoring processes. Eighteen students participated in Experiment 1, and 24 in Experiment 2. In Experiment 1, different target intrusion errors were found depending on different kinds of letters --romaji, hiragana, and kanji. In Experiment 2, stimulus set size and context information were manipulated in an attempt to explore the cause of post-target intrusion errors. Results showed that as stimulus set size increased, the post-target intrusion errors also increased, but contextual information did not affect the errors. Results concerning mean report probability indicated that increased allocation of attentional resource to response-defining dimension was the cause of the errors. In addition, results concerning confidence rating showed that monitoring of temporal and contextual information was extremely accurate, but it was not so for stimulus information. These results suggest that attentional resource is different from monitoring resource.

Variance adaptation in navigational decision making

NASA Astrophysics Data System (ADS)

Gershow, Marc; Gepner, Ruben; Wolk, Jason; Wadekar, Digvijay

Drosophila larvae navigate their environments using a biased random walk strategy. A key component of this strategy is the decision to initiate a turn (change direction) in response to declining conditions. We modeled this decision as the output of a Linear-Nonlinear-Poisson cascade and used reverse correlation with visual and fictive olfactory stimuli to find the parameters of this model. Because the larva responds to changes in stimulus intensity, we used stimuli with uncorrelated normally distributed intensity derivatives, i.e. Brownian processes, and took the stimulus derivative as the input to our LNP cascade. In this way, we were able to present stimuli with 0 mean and controlled variance. We found that the nonlinear rate function depended on the variance in the stimulus input, allowing larvae to respond more strongly to small changes in low-noise compared to high-noise environments. We measured the rate at which the larva adapted its behavior following changes in stimulus variance, and found that larvae adapted more quickly to increases in variance than to decreases, consistent with the behavior of an optimal Bayes estimator. Supported by NIH Grant 1DP2EB022359 and NSF Grant PHY-1455015.

Differences in reward processing between putative cell types in primate prefrontal cortex

PubMed Central

Fan, Hongwei; Wang, Rubin; Sakagami, Masamichi

2017-01-01

Single-unit studies in monkeys have demonstrated that neurons in the prefrontal cortex predict the reward type, reward amount or reward availability associated with a stimulus. To examine contributions of pyramidal cells and interneurons in reward processing, single-unit activity was extracellularly recorded in prefrontal cortices of four monkeys performing a reward prediction task. Based on their shapes of spike waveforms, prefrontal neurons were classified into broad-spike and narrow-spike units that represented putative pyramidal cells and interneurons, respectively. We mainly observed that narrow-spike neurons showed higher firing rates but less bursty discharges than did broad-spike neurons. Both narrow-spike and broad-spike cells selectively responded to the stimulus, reward and their interaction, and the proportions of each type of selective neurons were similar between the two cell classes. Moreover, the two types of cells displayed equal reliability of reward or stimulus discrimination. Furthermore, we found that broad-spike and narrow-spike cells showed distinct mechanisms for encoding reward or stimulus information. Broad-spike neurons raised their firing rate relative to the baseline rate to represent the preferred reward or stimulus information, whereas narrow-spike neurons inhibited their firing rate lower than the baseline rate to encode the non-preferred reward or stimulus information. Our results suggest that narrow-spike and broad-spike cells were equally involved in reward and stimulus processing in the prefrontal cortex. They utilized a binary strategy to complementarily represent reward or stimulus information, which was consistent with the task structure in which the monkeys were required to remember two reward conditions and two visual stimuli. PMID:29261734

Differences in reward processing between putative cell types in primate prefrontal cortex.

PubMed

Fan, Hongwei; Pan, Xiaochuan; Wang, Rubin; Sakagami, Masamichi

2017-01-01

Single-unit studies in monkeys have demonstrated that neurons in the prefrontal cortex predict the reward type, reward amount or reward availability associated with a stimulus. To examine contributions of pyramidal cells and interneurons in reward processing, single-unit activity was extracellularly recorded in prefrontal cortices of four monkeys performing a reward prediction task. Based on their shapes of spike waveforms, prefrontal neurons were classified into broad-spike and narrow-spike units that represented putative pyramidal cells and interneurons, respectively. We mainly observed that narrow-spike neurons showed higher firing rates but less bursty discharges than did broad-spike neurons. Both narrow-spike and broad-spike cells selectively responded to the stimulus, reward and their interaction, and the proportions of each type of selective neurons were similar between the two cell classes. Moreover, the two types of cells displayed equal reliability of reward or stimulus discrimination. Furthermore, we found that broad-spike and narrow-spike cells showed distinct mechanisms for encoding reward or stimulus information. Broad-spike neurons raised their firing rate relative to the baseline rate to represent the preferred reward or stimulus information, whereas narrow-spike neurons inhibited their firing rate lower than the baseline rate to encode the non-preferred reward or stimulus information. Our results suggest that narrow-spike and broad-spike cells were equally involved in reward and stimulus processing in the prefrontal cortex. They utilized a binary strategy to complementarily represent reward or stimulus information, which was consistent with the task structure in which the monkeys were required to remember two reward conditions and two visual stimuli.

Selective attention to affective value alters how the brain processes taste stimuli.

PubMed

Grabenhorst, Fabian; Rolls, Edmund T

2008-02-01

How does selective attention to affect influence sensory processing? In an fMRI investigation, when subjects were instructed to remember and rate the pleasantness of a taste stimulus, 0.1 M monosodium glutamate, activations were greater in the medial orbitofrontal and pregenual cingulate cortex than when subjects were instructed to remember and rate the intensity of the taste. When the subjects were instructed to remember and rate the intensity, activations were greater in the insular taste cortex. An interaction analysis showed that this dissociation of taste processing, depending on whether attention to pleasantness or intensity was relevant, was highly significant (P < 0.0002). Thus, depending on the context in which tastes are presented and whether affect is relevant, the brain responds to a taste differently. These findings show that, when attention is paid to affective value, the brain systems engaged to represent the sensory stimulus of taste are different from those engaged when attention is directed to the physical properties of a stimulus such as its intensity. This differential biasing of brain regions engaged in processing a sensory stimulus, depending on whether the cognitive demand is for affect-related vs. more sensory-related processing, may be an important aspect of cognition and attention. This has many implications for understanding the effects not only of taste but also of other sensory stimuli.

Alertness and cognitive control: Testing the early onset hypothesis.

PubMed

Schneider, Darryl W

2018-05-01

Previous research has revealed a peculiar interaction between alertness and cognitive control in selective-attention tasks: Congruency effects are larger on alert trials (on which an alerting cue is presented briefly in advance of the imperative stimulus) than on no-alert trials, despite shorter response times (RTs) on alert trials. One explanation for this finding is the early onset hypothesis, which is based on the assumptions that increased alertness shortens stimulus-encoding time and that cognitive control involves gradually focusing attention during a trial. The author tested the hypothesis in 3 experiments by manipulating alertness and stimulus quality (which were intended to shorten and lengthen stimulus-encoding time, respectively) in an arrow-based flanker task involving congruent and incongruent stimuli. Replicating past findings, the alerting manipulation led to shorter RTs but larger congruency effects on alert trials than on no-alert trials. The stimulus-quality manipulation led to longer RTs and larger congruency effects for degraded stimuli than for intact stimuli. These results provide mixed support for the early onset hypothesis, but the author discusses how data and theory might be reconciled if stimulus quality affects stimulus-encoding time and the rate of evidence accumulation in the decision process. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

The Socio-Moral Image Database (SMID): A novel stimulus set for the study of social, moral and affective processes.

PubMed

Crone, Damien L; Bode, Stefan; Murawski, Carsten; Laham, Simon M

2018-01-01

A major obstacle for the design of rigorous, reproducible studies in moral psychology is the lack of suitable stimulus sets. Here, we present the Socio-Moral Image Database (SMID), the largest standardized moral stimulus set assembled to date, containing 2,941 freely available photographic images, representing a wide range of morally (and affectively) positive, negative and neutral content. The SMID was validated with over 820,525 individual judgments from 2,716 participants, with normative ratings currently available for all images on affective valence and arousal, moral wrongness, and relevance to each of the five moral values posited by Moral Foundations Theory. We present a thorough analysis of the SMID regarding (1) inter-rater consensus, (2) rating precision, and (3) breadth and variability of moral content. Additionally, we provide recommendations for use aimed at efficient study design and reproducibility, and outline planned extensions to the database. We anticipate that the SMID will serve as a useful resource for psychological, neuroscientific and computational (e.g., natural language processing or computer vision) investigations of social, moral and affective processes. The SMID images, along with associated normative data and additional resources are available at https://osf.io/2rqad/.

Modulation-Frequency-Specific Adaptation in Awake Auditory Cortex

PubMed Central

Beitel, Ralph E.; Vollmer, Maike; Heiser, Marc A.; Schreiner, Christoph E.

2015-01-01

Amplitude modulations are fundamental features of natural signals, including human speech and nonhuman primate vocalizations. Because natural signals frequently occur in the context of other competing signals, we used a forward-masking paradigm to investigate how the modulation context of a prior signal affects cortical responses to subsequent modulated sounds. Psychophysical “modulation masking,” in which the presentation of a modulated “masker” signal elevates the threshold for detecting the modulation of a subsequent stimulus, has been interpreted as evidence of a central modulation filterbank and modeled accordingly. Whether cortical modulation tuning is compatible with such models remains unknown. By recording responses to pairs of sinusoidally amplitude modulated (SAM) tones in the auditory cortex of awake squirrel monkeys, we show that the prior presentation of the SAM masker elicited persistent and tuned suppression of the firing rate to subsequent SAM signals. Population averages of these effects are compatible with adaptation in broadly tuned modulation channels. In contrast, modulation context had little effect on the synchrony of the cortical representation of the second SAM stimuli and the tuning of such effects did not match that observed for firing rate. Our results suggest that, although the temporal representation of modulated signals is more robust to changes in stimulus context than representations based on average firing rate, this representation is not fully exploited and psychophysical modulation masking more closely mirrors physiological rate suppression and that rate tuning for a given stimulus feature in a given neuron's signal pathway appears sufficient to engender context-sensitive cortical adaptation. PMID:25878263

Changing the Tune: Listeners Like Music that Expresses a Contrasting Emotion

PubMed Central

Schellenberg, E. Glenn; Corrigall, Kathleen A.; Ladinig, Olivia; Huron, David

2012-01-01

Theories of esthetic appreciation propose that (1) a stimulus is liked because it is expected or familiar, (2) a stimulus is liked most when it is neither too familiar nor too novel, or (3) a novel stimulus is liked because it elicits an intensified emotional response. We tested the third hypothesis by examining liking for music as a function of whether the emotion it expressed contrasted with the emotion expressed by music heard previously. Stimuli were 30-s happy- or sad-sounding excerpts from recordings of classical piano music. On each trial, listeners heard a different excerpt and made liking and emotion-intensity ratings. The emotional character of consecutive excerpts was repeated with varying frequencies, followed by an excerpt that expressed a contrasting emotion. As the number of presentations of the background emotion increased, liking and intensity ratings became lower compared to those for the contrasting emotion. Consequently, when the emotional character of the music was relatively novel, listeners’ responses intensified and their appreciation increased. PMID:23269918

Auditory brainstem responses in the Eastern Screech Owl: An estimate of auditory thresholds

USGS Publications Warehouse

Brittan-Powell, E.F.; Lohr, B.; Hahn, D.C.; Dooling, R.J.

2005-01-01

The auditory brainstem response (ABR), a measure of neural synchrony, was used to estimate auditory sensitivity in the eastern screech owl (Megascops asio). The typical screech owl ABR waveform showed two to three prominent peaks occurring within 5 ms of stimulus onset. As sound pressure levels increased, the ABR peak amplitude increased and latency decreased. With an increasing stimulus presentation rate, ABR peak amplitude decreased and latency increased. Generally, changes in the ABR waveform to stimulus intensity and repetition rate are consistent with the pattern found in several avian families. The ABR audiogram shows that screech owls hear best between 1.5 and 6.4 kHz with the most acute sensitivity between 4?5.7 kHz. The shape of the average screech owl ABR audiogram is similar to the shape of the behaviorally measured audiogram of the barn owl, except at the highest frequencies. Our data also show differences in overall auditory sensitivity between the color morphs of screech owls.

Towards SSVEP-based, portable, responsive Brain-Computer Interface.

PubMed

Kaczmarek, Piotr; Salomon, Pawel

2015-08-01

A Brain-Computer Interface in motion control application requires high system responsiveness and accuracy. SSVEP interface consisted of 2-8 stimuli and 2 channel EEG amplifier was presented in this paper. The observed stimulus is recognized based on a canonical correlation calculated in 1 second window, ensuring high interface responsiveness. A threshold classifier with hysteresis (T-H) was proposed for recognition purposes. Obtained results suggest that T-H classifier enables to significantly increase classifier performance (resulting in accuracy of 76%, while maintaining average false positive detection rate of stimulus different then observed one between 2-13%, depending on stimulus frequency). It was shown that the parameters of T-H classifier, maximizing true positive rate, can be estimated by gradient-based search since the single maximum was observed. Moreover the preliminary results, performed on a test group (N=4), suggest that for T-H classifier exists a certain set of parameters for which the system accuracy is similar to accuracy obtained for user-trained classifier.

Transfer of stimulus control from a TFT to CRT screen.

PubMed

Railton, Renee Caron Richards; Foster, T Mary; Temple, William

2010-10-01

The use of television and computer screens for presenting stimuli to animals is increasing as it is non-invasive and can provide precise control over stimuli. Past studies have used cathode ray tube (CRT) screens; however, there is some evidence that these give different results to non-flickering thin film transistor (TFT) screens. Hens' critical flicker fusion frequency ranges between 80 and 90 Hz--above standard CRT screens. Thus, stimuli presented on CRT screens may appear distorted to hens. This study aimed to investigate whether changing the flicker rate of CRT screens altered hens' discrimination. Hens were trained (in a conditional discrimination) to discriminate between two stimuli on a TFT (flickerless) screen, and tested with the stimuli on a CRT screen at four flicker rates (60, 75, 85, and 100 Hz). The hens' accuracy generally decreased as the refresh rate of the CRT screen decreased. These results imply that the change in flicker rate changed the appearance of the stimuli enough to affect the hens' discrimination and stimulus control is disrupted when the stimuli appear to flicker. Copyright (c) 2010 Elsevier B.V. All rights reserved.

Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location

PubMed Central

Crago, Patrick E; Makowski, Nathan S

2014-01-01

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 interventions involving motor or sensory stimulation. PMID:25161163

Alteration of neural action potential patterns by axonal stimulation: the importance of stimulus location

NASA Astrophysics Data System (ADS)

Crago, Patrick E.; Makowski, Nathaniel S.

2014-10-01

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 interventions involving motor or sensory stimulation.

Top-down and bottom-up modulation of language related areas – An fMRI Study

PubMed Central

Noesselt, Tömme; Shah, Nadim Jon; Jäncke, Lutz

2003-01-01

Background One major problem for cognitive neuroscience is to describe the interaction between stimulus and task driven neural modulation. We used fMRI to investigate this interaction in the human brain. Ten male subjects performed a passive listening and a semantic categorization task in a factorial design. In both tasks, words were presented auditorily at three different rates. Results We found: (i) as word presentation rate increased hemodynamic responses increased bilaterally in the superior temporal gyrus including Heschl's gyrus (HG), the planum temporale (PT), and the planum polare (PP); (ii) compared to passive listening, semantic categorization produced increased bilateral activations in the ventral inferior frontal gyrus (IFG) and middle frontal gyrus (MFG); (iii) hemodynamic responses in the left dorsal IFG increased linearly with increasing word presentation rate only during the semantic categorization task; (iv) in the semantic task hemodynamic responses decreased bilaterally in the insula with increasing word presentation rates; and (v) in parts of the HG the hemodynamic response increased with increasing word presentation rates during passive listening more strongly. Conclusion The observed "rate effect" in primary and secondary auditory cortex is in accord with previous findings and suggests that these areas are driven by low-level stimulus attributes. The bilateral effect of semantic categorization is also in accord with previous studies and emphasizes the role of these areas in semantic operations. The interaction between semantic categorization and word presentation in the left IFG indicates that this area has linguistic functions not present in the right IFG. Finally, we speculate that the interaction between semantic categorization and word presentation rates in HG and the insula might reflect an inhibition of the transfer of unnecessary information from the temporal to frontal regions of the brain. PMID:12828789

STDP allows fast rate-modulated coding with Poisson-like spike trains.

PubMed

Gilson, Matthieu; Masquelier, Timothée; Hugues, Etienne

2011-10-01

Spike timing-dependent plasticity (STDP) has been shown to enable single neurons to detect repeatedly presented spatiotemporal spike patterns. This holds even when such patterns are embedded in equally dense random spiking activity, that is, in the absence of external reference times such as a stimulus onset. Here we demonstrate, both analytically and numerically, that STDP can also learn repeating rate-modulated patterns, which have received more experimental evidence, for example, through post-stimulus time histograms (PSTHs). Each input spike train is generated from a rate function using a stochastic sampling mechanism, chosen to be an inhomogeneous Poisson process here. Learning is feasible provided significant covarying rate modulations occur within the typical timescale of STDP (~10-20 ms) for sufficiently many inputs (~100 among 1000 in our simulations), a condition that is met by many experimental PSTHs. Repeated pattern presentations induce spike-time correlations that are captured by STDP. Despite imprecise input spike times and even variable spike counts, a single trained neuron robustly detects the pattern just a few milliseconds after its presentation. Therefore, temporal imprecision and Poisson-like firing variability are not an obstacle to fast temporal coding. STDP provides an appealing mechanism to learn such rate patterns, which, beyond sensory processing, may also be involved in many cognitive tasks.

STDP Allows Fast Rate-Modulated Coding with Poisson-Like Spike Trains

PubMed Central

Hugues, Etienne

2011-01-01

Spike timing-dependent plasticity (STDP) has been shown to enable single neurons to detect repeatedly presented spatiotemporal spike patterns. This holds even when such patterns are embedded in equally dense random spiking activity, that is, in the absence of external reference times such as a stimulus onset. Here we demonstrate, both analytically and numerically, that STDP can also learn repeating rate-modulated patterns, which have received more experimental evidence, for example, through post-stimulus time histograms (PSTHs). Each input spike train is generated from a rate function using a stochastic sampling mechanism, chosen to be an inhomogeneous Poisson process here. Learning is feasible provided significant covarying rate modulations occur within the typical timescale of STDP (∼10–20 ms) for sufficiently many inputs (∼100 among 1000 in our simulations), a condition that is met by many experimental PSTHs. Repeated pattern presentations induce spike-time correlations that are captured by STDP. Despite imprecise input spike times and even variable spike counts, a single trained neuron robustly detects the pattern just a few milliseconds after its presentation. Therefore, temporal imprecision and Poisson-like firing variability are not an obstacle to fast temporal coding. STDP provides an appealing mechanism to learn such rate patterns, which, beyond sensory processing, may also be involved in many cognitive tasks. PMID:22046113

Choice as a dependent measure in autoshaping: sensitivity to frequency and duration of food presentation.

PubMed Central

Picker, M; Poling, A

1982-01-01

Previous investigations have shown that rate, latency, and percentage of trials with at least one response are somewhat insensitive measures of the strength of autoshaped responding. In the present studies, these measures were contrasted with the allocation of responding during simultaneous choice tests, a measure of response strength frequently used in operant paradigms. In two experiments, nine pigeons were exposed to a forward pairing autoshaping procedure. Training sessions consisted of the successive presentation of three stimuli, each followed by food on either 100%, 50%, or 0% of the trials. Choice testing involved the simultaneous presentation of the three stimuli. In Experiment I, all pigeons consistently directed their initial choice responses and the majority of subsequent responses to the stimulus always followed by food, despite the fact that during training sessions the response rates of most birds were highest in the presence of the stimulus followed by food on 50% of the trials. In Experiment II, rate, latency, and percentage of trials with at least one response did not change appreciably as a function of duration of feeder presentations. However, choice responding was lawfully affected by duration of feeder presentations. These data suggest that choice is perhaps a more sensitive measure of the strength of autoshaped responding than other, more commonly employed, indices. PMID:7097152

Temporal properties of material categorization and material rating: visual vs non-visual material features.

PubMed

Nagai, Takehiro; Matsushima, Toshiki; Koida, Kowa; Tani, Yusuke; Kitazaki, Michiteru; Nakauchi, Shigeki

2015-10-01

Humans can visually recognize material categories of objects, such as glass, stone, and plastic, easily. However, little is known about the kinds of surface quality features that contribute to such material class recognition. In this paper, we examine the relationship between perceptual surface features and material category discrimination performance for pictures of materials, focusing on temporal aspects, including reaction time and effects of stimulus duration. The stimuli were pictures of objects with an identical shape but made of different materials that could be categorized into seven classes (glass, plastic, metal, stone, wood, leather, and fabric). In a pre-experiment, observers rated the pictures on nine surface features, including visual (e.g., glossiness and transparency) and non-visual features (e.g., heaviness and warmness), on a 7-point scale. In the main experiments, observers judged whether two simultaneously presented pictures were classified as the same or different material category. Reaction times and effects of stimulus duration were measured. The results showed that visual feature ratings were correlated with material discrimination performance for short reaction times or short stimulus durations, while non-visual feature ratings were correlated only with performance for long reaction times or long stimulus durations. These results suggest that the mechanisms underlying visual and non-visual feature processing may differ in terms of processing time, although the cause is unclear. Visual surface features may mainly contribute to material recognition in daily life, while non-visual features may contribute only weakly, if at all. Copyright © 2014 Elsevier Ltd. All rights reserved.

Neuron’s eye view: Inferring features of complex stimuli from neural responses

PubMed Central

Chen, Xin; Beck, Jeffrey M.

2017-01-01

Experiments that study neural encoding of stimuli at the level of individual neurons typically choose a small set of features present in the world—contrast and luminance for vision, pitch and intensity for sound—and assemble a stimulus set that systematically varies along these dimensions. Subsequent analysis of neural responses to these stimuli typically focuses on regression models, with experimenter-controlled features as predictors and spike counts or firing rates as responses. Unfortunately, this approach requires knowledge in advance about the relevant features coded by a given population of neurons. For domains as complex as social interaction or natural movement, however, the relevant feature space is poorly understood, and an arbitrary a priori choice of features may give rise to confirmation bias. Here, we present a Bayesian model for exploratory data analysis that is capable of automatically identifying the features present in unstructured stimuli based solely on neuronal responses. Our approach is unique within the class of latent state space models of neural activity in that it assumes that firing rates of neurons are sensitive to multiple discrete time-varying features tied to the stimulus, each of which has Markov (or semi-Markov) dynamics. That is, we are modeling neural activity as driven by multiple simultaneous stimulus features rather than intrinsic neural dynamics. We derive a fast variational Bayesian inference algorithm and show that it correctly recovers hidden features in synthetic data, as well as ground-truth stimulus features in a prototypical neural dataset. To demonstrate the utility of the algorithm, we also apply it to cluster neural responses and demonstrate successful recovery of features corresponding to monkeys and faces in the image set. PMID:28827790

Benign paroxysmal vertigo of childhood: diagnostic value of vestibular test and high stimulus rate auditory brainstem response test.

PubMed

Zhang, Daogong; Fan, Zhaomin; Han, Yuechen; Wang, Mingming; Xu, Lei; Luo, Jianfen; Ai, Yu; Wang, Haibo

2012-01-01

To investigate the diagnostic value of vestibular test and high stimulus rate auditory brainstem response (ABR) test and the possible mechanism responsible for benign paroxysmal vertigo of childhood (BPVC). Data of 56 patients with BPVC in vertigo clinic of our hospital from May 2007 to September 2008 were retrospectively analyzed in this study. Patients with BPVC were tested with pure tone audiometry, high stimulus rate auditory brainstem response test (ABR), transcranial Doppler sonography (TCD), bithermal caloric test, and VEMP. The results of the hearing and vestibular function test were compared and analyzed. There were 56 patients with BPVC, including 32 men, 24 women, aged 3-12 years old, with an average of 6.5 years. Among 56 cases of BPVC patients, the results of pure tone audiometry were all normal. High stimulus rate ABR was abnormal in 66.1% (37/56) of cases. TCD showed 57.1% abnormality in 56 cases, including faster flow rate in 28 cases and slower flow rate in 4 cases. High stimulus rate ABR and TCD were both abnormal in 48.2% (27/56) of cases. Bithermal caloric test was abnormal in 14.3% (8/56) of cases. VEMP showed 32.1% abnormality, including amplitude abnormality in 16 cases and latency abnormality in 2 cases. The abnormal rate of VEMP was much higher than that of caloric test. Vascular mechanisms might be involved in the pathogenesis of BPVC and there is strong evidence for close relationship between BPVC and migraine. High stimulus rate ABR is helpful in the diagnosis of BPVC. The inferior vestibular pathway is much more impaired than the superior vestibular pathway in BPVC. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Audio-visual synchrony and feature-selective attention co-amplify early visual processing.

PubMed

Keitel, Christian; Müller, Matthias M

2016-05-01

Our brain relies on neural mechanisms of selective attention and converging sensory processing to efficiently cope with rich and unceasing multisensory inputs. One prominent assumption holds that audio-visual synchrony can act as a strong attractor for spatial attention. Here, we tested for a similar effect of audio-visual synchrony on feature-selective attention. We presented two superimposed Gabor patches that differed in colour and orientation. On each trial, participants were cued to selectively attend to one of the two patches. Over time, spatial frequencies of both patches varied sinusoidally at distinct rates (3.14 and 3.63 Hz), giving rise to pulse-like percepts. A simultaneously presented pure tone carried a frequency modulation at the pulse rate of one of the two visual stimuli to introduce audio-visual synchrony. Pulsed stimulation elicited distinct time-locked oscillatory electrophysiological brain responses. These steady-state responses were quantified in the spectral domain to examine individual stimulus processing under conditions of synchronous versus asynchronous tone presentation and when respective stimuli were attended versus unattended. We found that both, attending to the colour of a stimulus and its synchrony with the tone, enhanced its processing. Moreover, both gain effects combined linearly for attended in-sync stimuli. Our results suggest that audio-visual synchrony can attract attention to specific stimulus features when stimuli overlap in space.

The adequate stimulus for avian short latency vestibular responses to linear translation

NASA Technical Reports Server (NTRS)

Jones, T. A.; Jones, S. M.; Colbert, S.

1998-01-01

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.

Anti-extinction in the tactile modality.

PubMed

White, Rebekah C; Aimola Davies, Anne M

2013-01-01

Patients with extinction fail to report a contralesional stimulus when it is presented at the same time as an ipsilesional stimulus, and patients with unilateral neglect fail to report a contralesional stimulus even when there is no competing ipsilesional stimulus. Whereas extinction and neglect are common following stroke, the related phenomenon of anti-extinction is rare--there are four cases of anti-extinction in the literature, and all four cases demonstrated anti-extinction in the visual modality. Patients with anti-extinction do report a contralesional stimulus when it is presented at the same time as an ipsilesional stimulus; but, like patients with neglect, they fail to report a contralesional stimulus when there is no competing ipsilesional stimulus. We present the first case ofanti-extinction in the tactile modality.

Subjective quality evaluation of low-bit-rate video

NASA Astrophysics Data System (ADS)

Masry, Mark; Hemami, Sheila S.; Osberger, Wilfried M.; Rohaly, Ann M.

2001-06-01

A subjective quality evaluation was performed to qualify vie4wre responses to visual defects that appear in low bit rate video at full and reduced frame rates. The stimuli were eight sequences compressed by three motion compensated encoders - Sorenson Video, H.263+ and a Wavelet based coder - operating at five bit/frame rate combinations. The stimulus sequences exhibited obvious coding artifacts whose nature differed across the three coders. The subjective evaluation was performed using the Single Stimulus Continuos Quality Evaluation method of UTI-R Rec. BT.500-8. Viewers watched concatenated coded test sequences and continuously registered the perceived quality using a slider device. Data form 19 viewers was colleted. An analysis of their responses to the presence of various artifacts across the range of possible coding conditions and content is presented. The effects of blockiness and blurriness on perceived quality are examined. The effects of changes in frame rate on perceived quality are found to be related to the nature of the motion in the sequence.

Maximally Informative Stimuli and Tuning Curves for Sigmoidal Rate-Coding Neurons and Populations

NASA Astrophysics Data System (ADS)

McDonnell, Mark D.; Stocks, Nigel G.

2008-08-01

A general method for deriving maximally informative sigmoidal tuning curves for neural systems with small normalized variability is presented. The optimal tuning curve is a nonlinear function of the cumulative distribution function of the stimulus and depends on the mean-variance relationship of the neural system. The derivation is based on a known relationship between Shannon’s mutual information and Fisher information, and the optimality of Jeffrey’s prior. It relies on the existence of closed-form solutions to the converse problem of optimizing the stimulus distribution for a given tuning curve. It is shown that maximum mutual information corresponds to constant Fisher information only if the stimulus is uniformly distributed. As an example, the case of sub-Poisson binomial firing statistics is analyzed in detail.

Selective attention to visual compound stimuli in squirrel monkeys (Saimiri sciureus).

PubMed

Ploog, Bertram O

2011-05-01

Five squirrel monkeys served under a simultaneous discrimination paradigm with visual compound stimuli that allowed measurement of excitatory and inhibitory control exerted by individual stimulus components (form and luminance/"color"), which could not be presented in isolation (i.e., form could not be presented without color). After performance exceeded a criterion of 75% correct during training, unreinforced test trials with stimuli comprising recombined training stimulus components were interspersed while the overall reinforcement rate remained constant for training and testing. The training-testing series was then repeated with reversed reinforcement contingencies. The findings were that color acquired greater excitatory control than form under the original condition, that no such difference was found for the reversal condition or for inhibitory control under either condition, and that overall inhibitory control was less pronounced than excitatory control. The remarkably accurate performance throughout suggested that a forced 4-s delay between the stimulus presentation and the opportunity to respond was effective in reducing "impulsive" responding, which has implications for suppressing impulsive responding in children with autism and with attention deficit disorder. Copyright © 2011 Elsevier B.V. All rights reserved.

Impact of stimulus uncanniness on speeded response

PubMed Central

Takahashi, Kohske; Fukuda, Haruaki; Samejima, Kazuyuki; Watanabe, Katsumi; Ueda, Kazuhiro

2015-01-01

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

Continuous- and discrete-time stimulus sequences for high stimulus rate paradigm in evoked potential studies.

PubMed

Wang, Tao; Huang, Jiang-hua; Lin, Lin; Zhan, Chang'an A

2013-01-01

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.

Effects of perceptual load and socially meaningful stimuli on crossmodal selective attention in Autism Spectrum Disorder and neurotypical samples.

PubMed

Tyndall, Ian; Ragless, Liam; O'Hora, Denis

2018-04-01

The present study examined whether increasing visual perceptual load differentially affected both Socially Meaningful and Non-socially Meaningful auditory stimulus awareness in neurotypical (NT, n = 59) adults and Autism Spectrum Disorder (ASD, n = 57) adults. On a target trial, an unexpected critical auditory stimulus (CAS), either a Non-socially Meaningful ('beep' sound) or Socially Meaningful ('hi') stimulus, was played concurrently with the presentation of the visual task. Under conditions of low visual perceptual load both NT and ASD samples reliably noticed the CAS at similar rates (77-81%), whether the CAS was Socially Meaningful or Non-socially Meaningful. However, during high visual perceptual load NT and ASD participants reliably noticed the meaningful CAS (NT = 71%, ASD = 67%), but NT participants were unlikely to notice the Non-meaningful CAS (20%), whereas ASD participants reliably noticed it (80%), suggesting an inability to engage selective attention to ignore non-salient irrelevant distractor stimuli in ASD. Copyright © 2018 Elsevier Inc. All rights reserved.

An improved P300 pattern in BCI to catch user’s attention

NASA Astrophysics Data System (ADS)

Jin, Jing; Zhang, Hanhan; Daly, Ian; Wang, Xingyu; Cichocki, Andrzej

2017-06-01

Objective. Brain-computer interfaces (BCIs) can help patients who have lost control over most muscles but are still conscious and able to communicate or interact with the environment. One of the most popular types of BCI is the P300-based BCI. With this BCI, users are asked to count the number of appearances of target stimuli in an experiment. To date, the majority of visual P300-based BCI systems developed have used the same character or picture as the target for every stimulus presentation, which can bore users. Consequently, users attention may decrease or be negatively affected by adjacent stimuli. Approach. In this study, a new stimulus is presented to increase user concentration. Honeycomb-shaped figures with 1-3 red dots were used as stimuli. The number and the positions of the red dots in the honeycomb-shaped figure were randomly changed during BCI control. The user was asked to count the number of the dots presented in each flash instead of the number of times they flashed. To assess the performance of this new stimulus, another honeycomb-shaped stimulus, without red dots, was used as a control condition. Main results. The results showed that the honeycomb-shaped stimuli with red dots obtained significantly higher classification accuracies and information transfer rates (p  <  0.05) compared to the honeycomb-shaped stimulus without red dots. Significance. The results indicate that this proposed method can be a promising approach to improve the performance of the BCI system and can be an efficient method in daily application.

An improved P300 pattern in BCI to catch user's attention.

PubMed

Jin, Jing; Zhang, Hanhan; Daly, Ian; Wang, Xingyu; Cichocki, Andrzej

2017-06-01

Brain-computer interfaces (BCIs) can help patients who have lost control over most muscles but are still conscious and able to communicate or interact with the environment. One of the most popular types of BCI is the P300-based BCI. With this BCI, users are asked to count the number of appearances of target stimuli in an experiment. To date, the majority of visual P300-based BCI systems developed have used the same character or picture as the target for every stimulus presentation, which can bore users. Consequently, users attention may decrease or be negatively affected by adjacent stimuli. In this study, a new stimulus is presented to increase user concentration. Honeycomb-shaped figures with 1-3 red dots were used as stimuli. The number and the positions of the red dots in the honeycomb-shaped figure were randomly changed during BCI control. The user was asked to count the number of the dots presented in each flash instead of the number of times they flashed. To assess the performance of this new stimulus, another honeycomb-shaped stimulus, without red dots, was used as a control condition. The results showed that the honeycomb-shaped stimuli with red dots obtained significantly higher classification accuracies and information transfer rates (p  <  0.05) compared to the honeycomb-shaped stimulus without red dots. The results indicate that this proposed method can be a promising approach to improve the performance of the BCI system and can be an efficient method in daily application.

The Socio-Moral Image Database (SMID): A novel stimulus set for the study of social, moral and affective processes

PubMed Central

Bode, Stefan; Murawski, Carsten; Laham, Simon M.

2018-01-01

A major obstacle for the design of rigorous, reproducible studies in moral psychology is the lack of suitable stimulus sets. Here, we present the Socio-Moral Image Database (SMID), the largest standardized moral stimulus set assembled to date, containing 2,941 freely available photographic images, representing a wide range of morally (and affectively) positive, negative and neutral content. The SMID was validated with over 820,525 individual judgments from 2,716 participants, with normative ratings currently available for all images on affective valence and arousal, moral wrongness, and relevance to each of the five moral values posited by Moral Foundations Theory. We present a thorough analysis of the SMID regarding (1) inter-rater consensus, (2) rating precision, and (3) breadth and variability of moral content. Additionally, we provide recommendations for use aimed at efficient study design and reproducibility, and outline planned extensions to the database. We anticipate that the SMID will serve as a useful resource for psychological, neuroscientific and computational (e.g., natural language processing or computer vision) investigations of social, moral and affective processes. The SMID images, along with associated normative data and additional resources are available at https://osf.io/2rqad/. PMID:29364985

Cue quality and criterion setting in recognition memory.

PubMed

Kent, Christopher; Lamberts, Koen; Patton, Richard

2018-02-02

Previous studies on how people set and modify decision criteria in old-new recognition tasks (in which they have to decide whether or not a stimulus was seen in a study phase) have almost exclusively focused on properties of the study items, such as presentation frequency or study list length. In contrast, in the three studies reported here, we manipulated the quality of the test cues in a scene-recognition task, either by degrading through Gaussian blurring (Experiment 1) or by limiting presentation duration (Experiment 2 and 3). In Experiments 1 and 2, degradation of the test cue led to worse old-new discrimination. Most importantly, however, participants were more liberal in their responses to degraded cues (i.e., more likely to call the cue "old"), demonstrating strong within-list, item-by-item, criterion shifts. This liberal response bias toward degraded stimuli came at the cost of increasing the false alarm rate while maintaining a constant hit rate. Experiment 3 replicated Experiment 2 with additional stimulus types (words and faces) but did not provide accuracy feedback to participants. The criterion shifts in Experiment 3 were smaller in magnitude than Experiments 1 and 2 and varied in consistency across stimulus type, suggesting, in line with previous studies, that feedback is important for participants to shift their criteria.

[The influence of click polarity and stimulation rate on the auditory evoked response in relation to age].

PubMed

Tarantino, V; Stura, M; Raspino, M; Conrad, E; Porcu, A

1989-01-01

In order to study the changes which occur in phase of the click stimulus and its relation to the stimulus repetition rate on the auditory brainstem response (ABR) as a function of age, the Authors recorded the ABR from the scalp's surface of 10 newborns and 40 infants, 3 months, 6 months, 1 year and 3 years old as well as from 10 normal adults. The stimulus was a square wave of 0.1 msec duration and 90 dBHL level. The stimulus equipment was calibrated twice under visual inspection to ensure that the C and R clicks resulted in an initial membrane deflection toward and from the ear drum respectively. No significant differences could be found for the latencies and amplitude in the C-R comparison. However, the mean values of the complete group of test subjects showed most intraindividual stability for the conventional click stimulation. The latency of the ABR with excitation of the cochlea seemed to be mainly determined by the internal oscillation sequence in the cochlea and not by the stimulus polarity. The amplitudes and latencies of the ABR components tend to decrease when the stimulus rate increases and the age decreases. The importance of the stimulus characteristics is discussed and some suggestions for clinical use of ABR are made.

An Analysis of "Reinforcement" History Effects

ERIC Educational Resources Information Center

Okouchi, Hiroto; Lattal, Kennon A.

2006-01-01

Four pigeons were exposed to two tandem variable-interval differential-reinforcement-of-low-rate schedules under different stimulus conditions. The values of the tandem schedules were adjusted so that reinforcement rates in one stimulus condition were higher than those in the other, even though response rates in the two conditions were nearly…

A Latent Class Unfolding Model for Analyzing Single Stimulus Preference Ratings.

ERIC Educational Resources Information Center

De Soete, Geert; Heiser, Willem J.

1993-01-01

A latent class unfolding model is developed for single stimulus preference ratings. One advantage is the possibility of testing the spatial unfolding model against the unconstrained latent class model for rating data. The model is applied to data about party preferences of members of the Dutch parliament. (SLD)

Habituation and sensitization of aggression in bullfrogs (Rana catesbeiana): testing the dual-process theory of habituation.

PubMed

Bee, M A

2001-09-01

The aggressive response of male bullfrogs (Rana catesbeiana) habituates with repeated broadcasts of acoustic stimuli simulating a new territorial neighbor. The effects of stimulus repetition rate and stimulus intensity on bullfrog aggressive responses were tested in a field experiment designed to test the assumptions of a dual-process theory of habituation. Synthetic advertisement calls were broadcast at 2 repetition rates and 2 intensities in a factorial design. Bullfrogs were more aggressive at the higher stimulus intensity at both repetition rates. Aggressive responses habituated more slowly at the higher stimulus intensity and slower repetition rate compared with other treatments. Several biotic and abiotic factors had small or negligible effects on aggressive responses. Although consistent with the operation of 2 opposing processes, habituation and sensitization, the data provide only partial support for the assumptions of dual-process theory.

Heart rate changes during electroconvulsive therapy

PubMed Central

2013-01-01

Background This observational study documented heart rate over the entire course of electrically induced seizures and aimed to evaluate the effects of stimulus electrode placement, patients' age, stimulus dose, and additional predictors. Method In 119 consecutive patients with 64 right unilateral (RUL) and 55 bifrontal (BF) electroconvulsive treatments, heart rate graphs based on beat-to-beat measurements were plotted up to durations of 130 s. Results In RUL stimulation, the initial drop in heart rate lasted for 12.5 ± 2.6 s (mean ± standard deviation). This depended on stimulus train duration, age, and baseline heart rate. In seizures induced with BF electrode placement, a sympathetic response was observed within the first few seconds of the stimulation phase (median 3.5 s). This was also the case with subconvulsive stimulations. The mean peak heart rate in all 119 treatments amounted to 135 ± 20 bpm and depended on baseline heart rate and seizure duration; electrode placement, charge dose, and age were insignificant in regression analysis. A marked decline in heart rate in connection with seizure cessation occurred in 71% of treatments. Conclusions A significant independent effect of stimulus electrode positioning on cardiac action was evident only in the initial phase of the seizures. Electrical stimulation rather than the seizure causes the initial heart rate increase in BF treatments. The data reveal no rationale for setting the stimulus doses as a function of intraictal peak heart rates (‘benchmark method’). The marked decline in heart rate at the end of most seizures is probably mediated by a baroreceptor reflex. PMID:23764036

Lesions to right posterior parietal cortex impair visual depth perception from disparity but not motion cues

PubMed Central

Leopold, David A.; Humphreys, Glyn W.; Welchman, Andrew E.

2016-01-01

The posterior parietal cortex (PPC) is understood to be active when observers perceive three-dimensional (3D) structure. However, it is not clear how central this activity is in the construction of 3D spatial representations. Here, we examine whether PPC is essential for two aspects of visual depth perception by testing patients with lesions affecting this region. First, we measured subjects' ability to discriminate depth structure in various 3D surfaces and objects using binocular disparity. Patients with lesions to right PPC (N = 3) exhibited marked perceptual deficits on these tasks, whereas those with left hemisphere lesions (N = 2) were able to reliably discriminate depth as accurately as control subjects. Second, we presented an ambiguous 3D stimulus defined by structure from motion to determine whether PPC lesions influence the rate of bistable perceptual alternations. Patients' percept durations for the 3D stimulus were generally within a normal range, although the two patients with bilateral PPC lesions showed the fastest perceptual alternation rates in our sample. Intermittent stimulus presentation reduced the reversal rate similarly across subjects. Together, the results suggest that PPC plays a causal role in both inferring and maintaining the perception of 3D structure with stereopsis supported primarily by the right hemisphere, but do not lend support to the view that PPC is a critical contributor to bistable perceptual alternations. This article is part of the themed issue ‘Vision in our three-dimensional world’. PMID:27269606

Perceptual and decisional factors influencing the discrimination of inversion in the Thatcher illusion.

PubMed

Cornes, Katherine; Donnelly, Nick; Godwin, Hayward; Wenger, Michael J

2011-06-01

The Thatcher illusion (Thompson, 1980) is considered to be a prototypical illustration of the notion that face perception is dependent on configural processes and representations. We explored this idea by examining the relative contributions of perceptual and decisional processes to the ability of observers to identify the orientation of two classes of forms-faces and churches-and a set of their component features. Observers were presented with upright and inverted images of faces and churches in which the components (eyes, mouth, windows, doors) were presented either upright or inverted. Observers first rated the subjective grotesqueness of all of the images and then performed a complete identification task in which they had to identify the orientation of the overall form and the orientation of each of the interior features. Grotesqueness ratings for both classes of image showed the standard modulation of rated grotesqueness as a function of orientation. The complete identification results revealed violations of both perceptual and decisional separability but failed to reveal any violations of within-stimulus (perceptual) independence. In addition, exploration of a simple bivariate Gaussian signal detection model of the relationship between identification performance and judged grotesqueness suggests that within-stimulus violations of perceptual independence on their own are insufficient for producing the illusion. This lack of evidence for within-stimulus configurality suggests the need for a critical reevaluation of the role of configural processing in the Thatcher illusion. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Speech rate reduction and "nasality" in normal speakers.

PubMed

Brancewicz, T M; Reich, A R

1989-12-01

This study explored the effects of reduced speech rate on nasal/voice accelerometric measures and nasality ratings. Nasal/voice accelerometric measures were obtained from normal adults for various speech stimuli and speaking rates. Stimuli included three sentences (one obstruent-loaded, one semivowel-loaded, and one containing a single nasal), and /pv/ syllable trains.. Speakers read the stimuli at their normal rate, half their normal rate, and as slowly as possible. In addition, a computer program paced each speaker at rates of 1, 2, and 3 syllables per second. The nasal/voice accelerometric values revealed significant stimulus effects but no rate effects. The nasality ratings of experienced listeners, evaluated as a function of stimulus and speaking rate, were compared to the accelerometric measures. The nasality scale values demonstrated small, but statistically significant, stimulus and rate effects. However, the nasality percepts were poorly correlated with the nasal/voice accelerometric measures.

The Role of Inhibition in a Computational Model of an Auditory Cortical Neuron during the Encoding of Temporal Information

PubMed Central

Bendor, Daniel

2015-01-01

In auditory cortex, temporal information within a sound is represented by two complementary neural codes: a temporal representation based on stimulus-locked firing and a rate representation, where discharge rate co-varies with the timing between acoustic events but lacks a stimulus-synchronized response. Using a computational neuronal model, we find that stimulus-locked responses are generated when sound-evoked excitation is combined with strong, delayed inhibition. In contrast to this, a non-synchronized rate representation is generated when the net excitation evoked by the sound is weak, which occurs when excitation is coincident and balanced with inhibition. Using single-unit recordings from awake marmosets (Callithrix jacchus), we validate several model predictions, including differences in the temporal fidelity, discharge rates and temporal dynamics of stimulus-evoked responses between neurons with rate and temporal representations. Together these data suggest that feedforward inhibition provides a parsimonious explanation of the neural coding dichotomy observed in auditory cortex. PMID:25879843

Bivariate autoregressive state-space modeling of psychophysiological time series data.

PubMed

Smith, Daniel M; Abtahi, Mohammadreza; Amiri, Amir Mohammad; Mankodiya, Kunal

2016-08-01

Heart rate (HR) and electrodermal activity (EDA) are often used as physiological measures of psychological arousal in various neuropsychology experiments. In this exploratory study, we analyze HR and EDA data collected from four participants, each with a history of suicidal tendencies, during a cognitive task known as the Paced Auditory Serial Addition Test (PASAT). A central aim of this investigation is to guide future research by assessing heterogeneity in the population of individuals with suicidal tendencies. Using a state-space modeling approach to time series analysis, we evaluate the effect of an exogenous input, i.e., the stimulus presentation rate which was increased systematically during the experimental task. Participants differed in several parameters characterizing the way in which psychological arousal was experienced during the task. Increasing the stimulus presentation rate was associated with an increase in EDA in participants 2 and 4. The effect on HR was positive for participant 2 and negative for participants 3 and 4. We discuss future directions in light of the heterogeneity in the population indicated by these findings.

Two-dimensional adaptation in the auditory forebrain

PubMed Central

Nagel, Katherine I.; Doupe, Allison J.

2011-01-01

Sensory neurons exhibit two universal properties: sensitivity to multiple stimulus dimensions, and adaptation to stimulus statistics. How adaptation affects encoding along primary dimensions is well characterized for most sensory pathways, but if and how it affects secondary dimensions is less clear. We studied these effects for neurons in the avian equivalent of primary auditory cortex, responding to temporally modulated sounds. We showed that the firing rate of single neurons in field L was affected by at least two components of the time-varying sound log-amplitude. When overall sound amplitude was low, neural responses were based on nonlinear combinations of the mean log-amplitude and its rate of change (first time differential). At high mean sound amplitude, the two relevant stimulus features became the first and second time derivatives of the sound log-amplitude. Thus a strikingly systematic relationship between dimensions was conserved across changes in stimulus intensity, whereby one of the relevant dimensions approximated the time differential of the other dimension. In contrast to stimulus mean, increases in stimulus variance did not change relevant dimensions, but selectively increased the contribution of the second dimension to neural firing, illustrating a new adaptive behavior enabled by multidimensional encoding. Finally, we demonstrated theoretically that inclusion of time differentials as additional stimulus features, as seen so prominently in the single-neuron responses studied here, is a useful strategy for encoding naturalistic stimuli, because it can lower the necessary sampling rate while maintaining the robustness of stimulus reconstruction to correlated noise. PMID:21753019

Better the devil you know? Nonconscious processing of identity and affect of famous faces.

PubMed

Stone, Anna; Valentine, Tim

2004-06-01

The nonconscious recognition of facial identity was investigated in two experiments featuring brief (17-msec) masked stimulus presentation to prevent conscious recognition. Faces were presented in simultaneous pairs of one famous face and one unfamiliar face, and participants attempted to select the famous face. Subsequently, participants rated the famous persons as "good" or "evil" (Experiment 1) or liked or disliked (Experiment 2). In Experiments 1 and 2, responses were less accurate to faces of persons rated evil/disliked than to faces of persons rated good/liked, and faces of persons rated evil/disliked were selected significantly below chance. Experiment 2 showed the effect in a within-items analysis: A famous face was selected less often by participants who disliked the person than by participants who liked the person, and the former were selected below chance accuracy. The within-items analysis rules out possible confounding factors based on variations in physical characteristics of the stimulus faces and confirms that the effects are due to participants' attitudes toward the famous persons. The results suggest that facial identity is recognized preconsciously, and that responses may be based on affect rather than familiarity.

Effects of allocation of attention on habituation to olfactory and visual food stimuli in children.

PubMed

Epstein, Leonard H; Saad, Frances G; Giacomelli, April M; Roemmich, James N

2005-02-15

Responding to food cues may be disrupted by allocating attention to other tasks. We report two experiments examining the effects of allocation of attention on salivary habituation to olfactory plus visual food cues in 8-12-year-old children. In Experiment 1, 42 children were presented with a series of 8 hamburger food stimulus presentations. During each intertrial interval, participants completed a controlled (hard), or automatic (easy) visual memory task, or no task (control). In Experiment 2, 22 children were presented with 10 presentations of a pizza food stimulus and either listened to an audiobook or no audiobook control. Results of Experiment 1 showed group differences in rate of change in salivation (p=0.014). Children in the controlled task did not habituate to repeated food cues, while children in the automatic (p<0.005) or no task (p<0.001) groups decreased responding over time. In Experiment 2, groups differed in the rate of change in salivation (p=0.004). Children in the no audiobook group habituated (p<0.001), while children in the audiobook group did not habituate. Changes in the rate of habituation when attending to non-food stimuli while eating may be a mechanism for increasing energy intake.

Evoking prescribed spike times in stochastic neurons

NASA Astrophysics Data System (ADS)

Doose, Jens; Lindner, Benjamin

2017-09-01

Single cell stimulation in vivo is a powerful tool to investigate the properties of single neurons and their functionality in neural networks. We present a method to determine a cell-specific stimulus that reliably evokes a prescribed spike train with high temporal precision of action potentials. We test the performance of this stimulus in simulations for two different stochastic neuron models. For a broad range of parameters and a neuron firing with intermediate firing rates (20-40 Hz) the reliability in evoking the prescribed spike train is close to its theoretical maximum that is mainly determined by the level of intrinsic noise.

Fear conditioning and stimulus generalization in patients with social anxiety disorder.

PubMed

Ahrens, Lea M; Pauli, Paul; Reif, Andreas; Mühlberger, Andreas; Langs, Gernot; Aalderink, Tim; Wieser, Matthias J

2016-12-01

Although overgeneralization seems to be a hallmark of several anxiety disorders, this until now has not been investigated in social anxiety disorder (SAD). Therefore, we examined fear generalization in 26 SAD patients and 29 healthy controls (HC) using two faces as conditioned stimuli (CS+, CS-), and a loud scream and a fearful face as unconditioned stimulus (US). Generalization was tested by presenting both CS and four morphs of the two faces (generalization stimuli [GSs]), while ratings, heart rate (HR) and skin conductance responses (SCR) were recorded. Results revealed that SAD patients rated all stimuli as less pleasant and more arousing compared to HC. Moreover, ratings and SCR indicated that both groups generalized their acquired fear from the CS+ to GSs. Remarkably, only SAD patients showed generalization in HR responses (fear bradycardia). Overall, SAD seems not to be characterized by strong overgeneralization but discrepancies in fear responses to both conditioned and generalized threat stimuli. Copyright © 2016 Elsevier Ltd. All rights reserved.

Discriminative stimulus effects of alpidem, a new imidazopyridine anxiolytic.

PubMed

Sanger, D J; Zivkovic, B

1994-01-01

Alpidem in an imidazopyridine derivative which binds selectively to the omega 1 (BZ1) receptor subtype. It is active in some, but not all, behavioural tests sensitive to benzodiazepine anxiolytics and has clinical anti-anxiety effects. However, in a previous study, it was shown that alpidem did not substitute for chlordiazepoxide in rats trained to discriminate this benzodiazepine. The present experiments were carried out to investigate the discriminative stimulus properties of alpidem in greater detail. In the first experiment rats learned to discriminate a dose of 10 mg/kg alpidem from saline. Acquisition of the discrimination was long and performance unstable. Chlordiazepoxide, clorazepate and zolpidem substituted only partially for alpidem but the effects of the training dose of alpidem were blocked by 10 mg/kg flumazenil. The second experiment established stimulus control more rapidly to a dose of 30 mg/kg alpidem. Alpidem induced dose-related stimulus control, and dose-related and complete substitution for alpidem was produced by zolpidem, abecarnil, CL 218,872, triazolam and suriclone. Partial substitution occurred with chlordiazepoxide, clorazepate and pentobarbital. In most cases, high levels of substitution were produced only by doses which greatly reduced response rates even though the training dose of alpidem produced only modest decreases in rates. Ethanol, buspirone and bretazenil produced very little substitution for alpidem and both flumazenil and bretazenil antagonised the effects of alpidem. In two further experiments alpidem was found to substitute for the stimulus produced by zolpidem (2 mg/kg) but not for that produced by ethanol (1.5 g/kg).(ABSTRACT TRUNCATED AT 250 WORDS)

Single neuron firing properties impact correlation-based population coding

PubMed Central

Hong, Sungho; Ratté, Stéphanie; Prescott, Steven A.; De Schutter, Erik

2012-01-01

Correlated spiking has been widely observed but its impact on neural coding remains controversial. Correlation arising from co-modulation of rates across neurons has been shown to vary with the firing rates of individual neurons. This translates into rate and correlation being equivalently tuned to the stimulus; under those conditions, correlated spiking does not provide information beyond that already available from individual neuron firing rates. Such correlations are irrelevant and can reduce coding efficiency by introducing redundancy. Using simulations and experiments in rat hippocampal neurons, we show here that pairs of neurons receiving correlated input also exhibit correlations arising from precise spike-time synchronization. Contrary to rate co-modulation, spike-time synchronization is unaffected by firing rate, thus enabling synchrony- and rate-based coding to operate independently. The type of output correlation depends on whether intrinsic neuron properties promote integration or coincidence detection: “ideal” integrators (with spike generation sensitive to stimulus mean) exhibit rate co-modulation whereas “ideal” coincidence detectors (with spike generation sensitive to stimulus variance) exhibit precise spike-time synchronization. Pyramidal neurons are sensitive to both stimulus mean and variance, and thus exhibit both types of output correlation proportioned according to which operating mode is dominant. Our results explain how different types of correlations arise based on how individual neurons generate spikes, and why spike-time synchronization and rate co-modulation can encode different stimulus properties. Our results also highlight the importance of neuronal properties for population-level coding insofar as neural networks can employ different coding schemes depending on the dominant operating mode of their constituent neurons. PMID:22279226

Acoustic landmarks drive delta-theta oscillations to enable speech comprehension by facilitating perceptual parsing

PubMed Central

Doelling, Keith; Arnal, Luc; Ghitza, Oded; Poeppel, David

2013-01-01

A growing body of research suggests that intrinsic neuronal slow (< 10 Hz) oscillations in auditory cortex appear to track incoming speech and other spectro-temporally complex auditory signals. Within this framework, several recent studies have identified critical-band temporal envelopes as the specific acoustic feature being reflected by the phase of these oscillations. However, how this alignment between speech acoustics and neural oscillations might underpin intelligibility is unclear. Here we test the hypothesis that the ‘sharpness’ of temporal fluctuations in the critical band envelope acts as a temporal cue to speech syllabic rate, driving delta-theta rhythms to track the stimulus and facilitate intelligibility. We interpret our findings as evidence that sharp events in the stimulus cause cortical rhythms to re-align and parse the stimulus into syllable-sized chunks for further decoding. Using magnetoencephalographic recordings, we show that by removing temporal fluctuations that occur at the syllabic rate, envelope-tracking activity is reduced. By artificially reinstating these temporal fluctuations, envelope-tracking activity is regained. These changes in tracking correlate with intelligibility of the stimulus. Together, the results suggest that the sharpness of fluctuations in the stimulus, as reflected in the cochlear output, drive oscillatory activity to track and entrain to the stimulus, at its syllabic rate. This process likely facilitates parsing of the stimulus into meaningful chunks appropriate for subsequent decoding, enhancing perception and intelligibility. PMID:23791839

Autonomic responses to tonic pain are more closely related to stimulus intensity than to pain intensity.

PubMed

Nickel, Moritz M; May, Elisabeth S; Tiemann, Laura; Postorino, Martina; Ta Dinh, Son; Ploner, Markus

2017-11-01

Pain serves the protection of the body by translating noxious stimulus information into a subjective percept and protective responses. Such protective responses rely on autonomic responses that allocate energy resources to protective functions. However, the precise relationship between objective stimulus intensity, subjective pain intensity, autonomic responses, and brain activity is not fully clear yet. Here, we addressed this question by continuously recording pain ratings, skin conductance, heart rate, and electroencephalography during tonic noxious heat stimulation of the hand in 39 healthy human subjects. The results confirmed that pain intensity dissociates from stimulus intensity during 10 minutes of noxious stimulation. Furthermore, skin conductance measures were significantly related to stimulus intensity but not to pain intensity. Correspondingly, skin conductance measures were significantly related to alpha and beta oscillations in contralateral sensorimotor cortex, which have been shown to encode stimulus intensity rather than pain intensity. No significant relationships were found between heart rate and stimulus intensity or pain intensity. The findings were consistent for stimulation of the left and the right hands. These results suggest that sympathetic autonomic responses to noxious stimuli in part directly result from nociceptive rather than from perceptual processes. Beyond, these observations support concepts of pain and emotions in which sensory, motor, and autonomic components are partially independent processes that together shape emotional and painful experiences.

Effect of a combination of flip and zooming stimuli on the performance of a visual brain-computer interface for spelling.

PubMed

Cheng, Jiao; Jin, Jing; Daly, Ian; Zhang, Yu; Wang, Bei; Wang, Xingyu; Cichocki, Andrzej

2018-02-13

Brain-computer interface (BCI) systems can allow their users to communicate with the external world by recognizing intention directly from their brain activity without the assistance of the peripheral motor nervous system. The P300-speller is one of the most widely used visual BCI applications. In previous studies, a flip stimulus (rotating the background area of the character) that was based on apparent motion, suffered from less refractory effects. However, its performance was not improved significantly. In addition, a presentation paradigm that used a "zooming" action (changing the size of the symbol) has been shown to evoke relatively higher P300 amplitudes and obtain a better BCI performance. To extend this method of stimuli presentation within a BCI and, consequently, to improve BCI performance, we present a new paradigm combining both the flip stimulus with a zooming action. This new presentation modality allowed BCI users to focus their attention more easily. We investigated whether such an action could combine the advantages of both types of stimuli presentation to bring a significant improvement in performance compared to the conventional flip stimulus. The experimental results showed that the proposed paradigm could obtain significantly higher classification accuracies and bit rates than the conventional flip paradigm (p<0.01).

Application of psychometric theory to the measurement of voice quality using rating scales.

PubMed

Shrivastav, Rahul; Sapienza, Christine M; Nandur, Vuday

2005-04-01

Rating scales are commonly used to study voice quality. However, recent research has demonstrated that perceptual measures of voice quality obtained using rating scales suffer from poor interjudge agreement and reliability, especially in the mid-range of the scale. These findings, along with those obtained using multidimensional scaling (MDS), have been interpreted to show that listeners perceive voice quality in an idiosyncratic manner. Based on psychometric theory, the present research explored an alternative explanation for the poor interlistener agreement observed in previous research. This approach suggests that poor agreement between listeners may result, in part, from measurement errors related to a variety of factors rather than true differences in the perception of voice quality. In this study, 10 listeners rated breathiness for 27 vowel stimuli using a 5-point rating scale. Each stimulus was presented to the listeners 10 times in random order. Interlistener agreement and reliability were calculated from these ratings. Agreement and reliability were observed to improve when multiple ratings of each stimulus from each listener were averaged and when standardized scores were used instead of absolute ratings. The probability of exact agreement was found to be approximately .9 when using averaged ratings and standardized scores. In contrast, the probability of exact agreement was only .4 when a single rating from each listener was used to measure agreement. These findings support the hypothesis that poor agreement reported in past research partly arises from errors in measurement rather than individual differences in the perception of voice quality.

Striatal-Limbic Activation is Associated with Intensity of Anticipatory Anxiety

PubMed Central

Yang, Hongyu; Spence, Jeffrey S.; Devous, Michael D.; Briggs, Richard W.; Goyal, Aman; Xiao, Hong; Yadav, Hardik; Adinoff, Bryon

2013-01-01

Anxiety experienced in anticipation of impending aversive events induces striatal-limbic activation. However, previous functional magnetic imaging (fMRI) studies of anticipatory anxiety have utilized post-test measures of anxiety, making a direct association between neural activation and distress problematic. This paradigm was designed to assess the BOLD response to an aversive conditioned stimulus while simultaneously measuring subjective anxiety. Fifteen male healthy subjects (45.5±8.5 years old) were studied. A high threat conditioned stimulus (CS) was paired with either an unpredictable, highly aversive (painful) or a non-aversive (non-painful) unconditioned stimulus and compared to a low threat CS paired with a predictable, non-aversive stimulus. Neural response was assessed with fMRI, and subjective anxiety (1 to 4) was recorded upon the presentation of each CS. High subjective ratings of real-time anticipatory anxiety (2, 3, and 4), relative to low anticipatory anxiety (1), elicited increased activation in the bilateral striatum, bilateral orbital frontal cortex, left anterior insula, and anterior cingulate cortex (ACC) and decreased activation in the posterior cingulate cortex (PCC). The amplitude of BOLD signal change generally paralleled the subjective rating of anxiety. Real-time measures of anticipatory anxiety confirm previous reports, using post-test measures of anxiety, of striatal-limbic activation during anticipatory anxiety while simultaneously demonstrating an increase in BOLD response in parallel with heightened anxiety. PMID:23137803

Low frequency mechanical actuation accelerates reperfusion in-vitro

PubMed Central

2013-01-01

Background Rapid restoration of vessel patency after acute myocardial infarction is key to reducing myocardial muscle death and increases survival rates. Standard therapies include thrombolysis and direct PTCA. Alternative or adjunctive emergency therapies that could be initiated by minimally trained personnel in the field are of potential clinical benefit. This paper evaluates a method of accelerating reperfusion through application of low frequency mechanical stimulus to the blood carrying vessels. Materials and method We consider a stenosed, heparinized flow system with aortic-like pressure variations subject to direct vessel vibration at the occlusion site or vessel deformation proximal and distal to the occlusion site, versus a reference system lacking any form of mechanical stimulus on the vessels. Results The experimental results show limited effectiveness of the direct mechanical vibration method and a drastic increase in the patency rate when vessel deformation is induced. For vessel deformation at occlusion site 95% of clots perfused within 11 minutes of application of mechanical stimulus, for vessel deformation 60 centimeters from the occlusion site 95% percent of clots perfused within 16 minutes of stimulus application, while only 2.3% of clots perfused within 20 minutes in the reference system. Conclusion The presented in-vitro results suggest that low frequency mechanical actuation applied during the pre-hospitalization phase in patients with acute myocardial infarction have potential of being a simple and efficient adjunct therapy. PMID:24257116

COMMUNICATION: Electrophysiological response dynamics during focal cortical infarction

NASA Astrophysics Data System (ADS)

Chiganos, Terry C., Jr.; Jensen, Winnie; Rousche, Patrick J.

2006-12-01

While the intracellular processes of hypoxia-induced necrosis and the intercellular mechanisms of post-ischemic neurotoxicity associated with stroke are well documented, the dynamic electrophysiological (EP) response of neurons within the core or periinfarct zone remains unclear. The present study validates a method for continuous measurement of the local EP responses during focal cortical infarction induced via photothrombosis. Single microwire electrodes were acutely implanted into the primary auditory cortex of eight rats. Multi-unit neural activity, evoked via a continuous 2 Hz click stimulus, was recorded before, during and after infarction to assess neuronal function in response to local, permanent ischemia. During sham infarction, the average stimulus-evoked peak firing rate over 20 min remained stable at 495.5 ± 14.5 spikes s-1, indicating temporal stability of neural function under normal conditions. Stimulus-evoked peak firing was reliably reduced to background levels (firing frequency in the absence of stimulus) following initiation of photothrombosis over a period of 439 ± 92 s. The post-infarction firing patterns exhibited unique temporal degradation of the peak firing rate, suggesting a variable response to ischemic challenge. Despite the inherent complexity of cerebral ischemia secondary to microvascular occlusion, complete loss of EP function consistently occurred 300-600 s after photothrombosis. The results suggest that microwire recording during photothrombosis provides a simple and highly efficacious strategy for assessing the electrophysiological dynamics of cortical infarction.

The ToMenovela – A Photograph-Based Stimulus Set for the Study of Social Cognition with High Ecological Validity

PubMed Central

Herbort, Maike C.; Iseev, Jenny; Stolz, Christopher; Roeser, Benedict; Großkopf, Nora; Wüstenberg, Torsten; Hellweg, Rainer; Walter, Henrik; Dziobek, Isabel; Schott, Björn H.

2016-01-01

We present the ToMenovela, a stimulus set that has been developed to provide a set of normatively rated socio-emotional stimuli showing varying amount of characters in emotionally laden interactions for experimental investigations of (i) cognitive and (ii) affective Theory of Mind (ToM), (iii) emotional reactivity, and (iv) complex emotion judgment with respect to Ekman’s basic emotions (happiness, anger, disgust, fear, sadness, surprise, Ekman and Friesen, 1975). Stimuli were generated with focus on ecological validity and consist of 190 scenes depicting daily-life situations. Two or more of eight main characters with distinct biographies and personalities are depicted on each scene picture. To obtain an initial evaluation of the stimulus set and to pave the way for future studies in clinical populations, normative data on each stimulus of the set was obtained from a sample of 61 neurologically and psychiatrically healthy participants (31 female, 30 male; mean age 26.74 ± 5.84), including a visual analog scale rating of Ekman’s basic emotions (happiness, anger, disgust, fear, sadness, surprise) and free-text descriptions of the content of each scene. The ToMenovela is being developed to provide standardized material of social scenes that are available to researchers in the study of social cognition. It should facilitate experimental control while keeping ecological validity high. PMID:27994562

Using a Regression Method for Estimating Performance in a Rapid Serial Visual Presentation Target-Detection Task

DTIC Science & Technology

2017-12-01

values designating each stimulus as a target ( true ) or nontarget (false). Both stim_time and stim_label should have length equal to the number of...position unless so designated by other authorized documents. Citation of manufacturer’s or trade names does not constitute an official endorsement or...depend strongly on the true values of hit rate and false-alarm rate. Based on its better estimation of hit rate and false-alarm rate, the regression

Some relations between classically conditioned aggression and conditioned suppression in squirrel monkeys.

PubMed Central

Hake, D F; Campbell, R L

1980-01-01

During three experiments with squirrel monkeys, stimulus and shock pairings were given in the presence of a bite tube. Experiments 1 and 2 used a conditioned-suppression procedure in which bar pressing was reinforced with food. A transparent shield prevented biting of the bar. When the stimulus was paired with shock, bar pressing decreased (conditioned suppression) and tube biting increased during the stimulus (classically conditioned aggression). When the bite tube was removed on alternate sessions in Experiment 2, there was more suppression when the tube was present, thus suggesting that biting competed with bar pressing. However, this simple competing-response interpretation was complicated by the findings of Experiment 3 where, with naive monkeys, bar pressing was never reinforced with food, yet bar pressing was induced during the stimulus and was highest when the bite tube was absent. The fact that stimulus-induced bar pressing developed inciated that bar pressing in conditioned-suppression procedures, suppressed or not, may be maintained by two types of control--the food reinforcer and induced CS control. The higher rate of induced bar pressing during the stimulus with the bite tube absent confounds a simple competing response interpretation of conditioned suppression. It suggests that shock-induced responses during conditioned suppression could be both contributing to and competing with responding maintained by food, with the net effect depending on specific but ill-defined features of the situation. PMID:7190996

Chaos-induced modulation of reliability boosts output firing rate in downstream cortical areas.

PubMed

Tiesinga, P H E

2004-03-01

The reproducibility of neural spike train responses to an identical stimulus across different presentations (trials) has been studied extensively. Reliability, the degree of reproducibility of spike trains, was found to depend in part on the amplitude and frequency content of the stimulus [J. Hunter and J. Milton, J. Neurophysiol. 90, 387 (2003)]. The responses across different trials can sometimes be interpreted as the response of an ensemble of similar neurons to a single stimulus presentation. How does the reliability of the activity of neural ensembles affect information transmission between different cortical areas? We studied a model neural system consisting of two ensembles of neurons with Hodgkin-Huxley-type channels. The first ensemble was driven by an injected sinusoidal current that oscillated in the gamma-frequency range (40 Hz) and its output spike trains in turn drove the second ensemble by fast excitatory synaptic potentials with short term depression. We determined the relationship between the reliability of the first ensemble and the response of the second ensemble. In our paradigm the neurons in the first ensemble were initially in a chaotic state with unreliable and imprecise spike trains. The neurons became entrained to the oscillation and responded reliably when the stimulus power was increased by less than 10%. The firing rate of the first ensemble increased by 30%, whereas that of the second ensemble could increase by an order of magnitude. We also determined the response of the second ensemble when its input spike trains, which had non-Poisson statistics, were replaced by an equivalent ensemble of Poisson spike trains. The resulting output spike trains were significantly different from the original response, as assessed by the metric introduced by Victor and Purpura [J. Neurophysiol. 76, 1310 (1996)]. These results are a proof of principle that weak temporal modulations in the power of gamma-frequency oscillations in a given cortical area can strongly affect firing rate responses downstream by way of reliability in spite of rather modest changes in firing rate in the originating area.

Why Additional Presentations Help Identify a Stimulus

ERIC Educational Resources Information Center

Guest, Duncan; Kent, Christopher; Adelman, James S.

2010-01-01

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…

Methamphetamine enhances sexual behavior in female rats.

PubMed

Winland, Carissa; Haycox, Charles; Bolton, Jessica L; Jampana, Sumith; Oakley, Benjamin J; Ford, Brittany; Ornelas, Laura; Burbey, Alexandra; Marquette, Amber; Frohardt, Russell J; Guarraci, Fay A

2011-06-01

The present study evaluated the effects of methamphetamine (MA) on sexual behavior in female rats. In Experiment 1, ovariectomized, hormone-primed rats were injected with MA (1.0mg/kg, i.p.) or saline prior to a test for mate choice wherein females could mate with two males simultaneously. Female rats treated with saline returned to their preferred mate faster after receiving intromissions and visited their preferred mate at a higher rate than their non-preferred mate. In contrast, MA-treated female rats spent a similar amount of time with their preferred and non-preferred mate and failed to return to their preferred mate faster than to their non-preferred mate following intromissions. Two weeks later, the females received the same drug treatment but were tested for partner preference wherein females could spend time near a male or female stimulus rat. All subjects spent more time near the male stimulus than the female stimulus. However, the MA-treated rats visited the male stimulus more frequently and spent less time near the female stimulus than the saline-treated rats. Similar to Experiment 1, female rats in Experiment 2 were tested for mate choice and then two weeks later tested for partner preference; however, females received three daily injections of MA (1.0mg/kg, i.p.) or saline. Females treated chronically with MA returned to both males faster following intromissions than females treated with saline, independent of preference (i.e., preferred mate and non-preferred mate). Furthermore, MA-treated rats were more likely to leave either male (i.e., preferred or non-preferred mate) than saline-treated rats after receiving sexual stimulation. Although MA-treated subjects spent more time near the male stimulus than the female stimulus, they spent less time near either when compared to saline-treated subjects. The present results demonstrate that MA affects sexual behavior in female rats partly by increasing locomotion and partly by directly affecting sexual behavior. Copyright © 2011 Elsevier Inc. All rights reserved.

Gender differences in judgments of multiple emotions from facial expressions.

PubMed

Hall, Judith A; Matsumoto, David

2004-06-01

The authors tested gender differences in emotion judgments by utilizing a new judgment task (Studies 1 and 2) and presenting stimuli at the edge of conscious awareness (Study 2). Women were more accurate than men even under conditions of minimal stimulus information. Women's ratings were more variable across scales, and they rated correct target emotions higher than did men. Copyright 2004 American Psychological Association

The Role of Temporal Disparity on Audiovisual Integration in Low-Vision Individuals.

PubMed

Targher, Stefano; Micciolo, Rocco; Occelli, Valeria; Zampini, Massimiliano

2017-12-01

Recent findings have shown that sounds improve visual detection in low vision individuals when the audiovisual stimuli pairs of stimuli are presented simultaneously and from the same spatial position. The present study purports to investigate the temporal aspects of the audiovisual enhancement effect previously reported. Low vision participants were asked to detect the presence of a visual stimulus (yes/no task) presented either alone or together with an auditory stimulus at different stimulus onset asynchronies (SOAs). In the first experiment, the sound was presented either simultaneously or before the visual stimulus (i.e., SOAs 0, 100, 250, 400 ms). The results show that the presence of a task-irrelevant auditory stimulus produced a significant visual detection enhancement in all the conditions. In the second experiment, the sound was either synchronized with, or randomly preceded/lagged behind the visual stimulus (i.e., SOAs 0, ± 250, ± 400 ms). The visual detection enhancement was reduced in magnitude and limited only to the synchronous condition and to the condition in which the sound stimulus was presented 250 ms before the visual stimulus. Taken together, the evidence of the present study seems to suggest that audiovisual interaction in low vision individuals is highly modulated by top-down mechanisms.

BESST (Bochum Emotional Stimulus Set)--a pilot validation study of a stimulus set containing emotional bodies and faces from frontal and averted views.

PubMed

Thoma, Patrizia; Soria Bauser, Denise; Suchan, Boris

2013-08-30

This article introduces the freely available Bochum Emotional Stimulus Set (BESST), which contains pictures of bodies and faces depicting either a neutral expression or one of the six basic emotions (happiness, sadness, fear, anger, disgust, and surprise), presented from two different perspectives (0° frontal view vs. camera averted by 45° to the left). The set comprises 565 frontal view and 564 averted view pictures of real-life bodies with masked facial expressions and 560 frontal and 560 averted view faces which were synthetically created using the FaceGen 3.5 Modeller. All stimuli were validated in terms of categorization accuracy and the perceived naturalness of the expression. Additionally, each facial stimulus was morphed into three age versions (20/40/60 years). The results show high recognition of the intended facial expressions, even under speeded forced-choice conditions, as corresponds to common experimental settings. The average naturalness ratings for the stimuli range between medium and high. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Peripheral prism glasses: effects of moving and stationary backgrounds.

PubMed

Shen, Jieming; Peli, Eli; Bowers, Alex R

2015-04-01

Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance and partial suppression of the prism image, thereby limiting device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared with monocular viewing. Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than in monocular (prism eye) viewing on the motion background (medians, 13 and 58%, respectively, p = 0.008) but not the still frame background (medians, 63 and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in one HH and one normally sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations.

Peripheral Prism Glasses: Effects of Moving and Stationary Backgrounds

PubMed Central

Shen, Jieming; Peli, Eli; Bowers, Alex R.

2015-01-01

Purpose Unilateral peripheral prisms for homonymous hemianopia (HH) expand the visual field through peripheral binocular visual confusion, a stimulus for binocular rivalry that could lead to reduced predominance (partial local suppression) of the prism image and limit device functionality. Using natural-scene images and motion videos, we evaluated whether detection was reduced in binocular compared to monocular viewing. Methods Detection rates of nine participants with HH or quadranopia and normal binocularity wearing peripheral prisms were determined for static checkerboard perimetry targets briefly presented in the prism expansion area and the seeing hemifield. Perimetry was conducted under monocular and binocular viewing with targets presented over videos of real-world driving scenes and still frame images derived from those videos. Results With unilateral prisms, detection rates in the prism expansion area were significantly lower in binocular than monocular (prism eye) viewing on the motion background (medians 13% and 58%, respectively, p = 0.008), but not the still frame background (63% and 68%, p = 0.123). When the stimulus for binocular rivalry was reduced by fitting prisms bilaterally in 1 HH and 1 normally-sighted subject with simulated HH, prism-area detection rates on the motion background were not significantly different (p > 0.6) in binocular and monocular viewing. Conclusions Conflicting binocular motion appears to be a stimulus for reduced predominance of the prism image in binocular viewing when using unilateral peripheral prisms. However, the effect was only found for relatively small targets. Further testing is needed to determine the extent to which this phenomenon might affect the functionality of unilateral peripheral prisms in more real-world situations. PMID:25785533

Expectancy Effects on Conditioned Pain Modulation Are Not Influenced by Naloxone or Morphine.

PubMed

France, Christopher R; Burns, John W; Gupta, Rajnish K; Buvanendran, Asokumar; Chont, Melissa; Schuster, Erik; Orlowska, Daria; Bruehl, Stephen

2016-08-01

Recent studies suggest that participant expectations influence pain ratings during conditioned pain modulation testing. The present study extends this work by examining expectancy effects among individuals with and without chronic back pain after administration of placebo, naloxone, or morphine. This study aims to identify the influence of individual differences in expectancy on changes in heat pain ratings obtained before, during, and after a forearm ischemic pain stimulus. Participants with chronic low back pain (n = 88) and healthy controls (n = 100) rated heat pain experience (i.e., "test stimulus") before, during, and after exposure to ischemic pain (i.e., "conditioning stimulus"). Prior to testing, participants indicated whether they anticipated that their heat pain would increase, decrease, or remain unchanged during ischemic pain. Analysis of the effects of expectancy (pain increase, decrease, or no change), drug (placebo, naloxone, or morphine), and group (back pain, healthy) on changes in heat pain revealed a significant main effect of expectancy (p = 0.001), but no other significant main effects or interactions. Follow-up analyses revealed that individuals who expected lower pain during ischemia reported significantly larger decreases in heat pain as compared with those who expected either no change (p = 0.004) or increased pain (p = 0.001). The present findings confirm that expectancy is an important contributor to conditioned pain modulation effects, and therefore significant caution is needed when interpreting findings that do not account for this individual difference. Opioid mechanisms do not appear to be involved in these expectancy effects.

Temporal Specificity in Pavlovian-Toinstrumental Transfer

ERIC Educational Resources Information Center

Matell, Matthew S.; Della Valle, Rebecca B.

2018-01-01

Presentation of a previously trained Pavlovian conditioned stimulus while an organism is engaged in operant responding can moderate the rate of responding, a phenomenon known as Pavlovian-to-instrumental transfer. Although it is well known that Pavlovian contingencies will generate conditioned behavior that is temporally organized with respect to…

The Nencki Affective Picture System (NAPS): introduction to a novel, standardized, wide-range, high-quality, realistic picture database.

PubMed

Marchewka, Artur; Zurawski, Łukasz; Jednoróg, Katarzyna; Grabowska, Anna

2014-06-01

Selecting appropriate stimuli to induce emotional states is essential in affective research. Only a few standardized affective stimulus databases have been created for auditory, language, and visual materials. Numerous studies have extensively employed these databases using both behavioral and neuroimaging methods. However, some limitations of the existing databases have recently been reported, including limited numbers of stimuli in specific categories or poor picture quality of the visual stimuli. In the present article, we introduce the Nencki Affective Picture System (NAPS), which consists of 1,356 realistic, high-quality photographs that are divided into five categories (people, faces, animals, objects, and landscapes). Affective ratings were collected from 204 mostly European participants. The pictures were rated according to the valence, arousal, and approach-avoidance dimensions using computerized bipolar semantic slider scales. Normative ratings for the categories are presented for each dimension. Validation of the ratings was obtained by comparing them to ratings generated using the Self-Assessment Manikin and the International Affective Picture System. In addition, the physical properties of the photographs are reported, including luminance, contrast, and entropy. The new database, with accompanying ratings and image parameters, allows researchers to select a variety of visual stimulus materials specific to their experimental questions of interest. The NAPS system is freely accessible to the scientific community for noncommercial use by request at http://naps.nencki.gov.pl .

Stimulus Probability Effects in Absolute Identification

ERIC Educational Resources Information Center

Kent, Christopher; Lamberts, Koen

2016-01-01

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…

Multiple serial picture presentation with millisecond resolution using a three-way LC-shutter-tachistoscope

PubMed Central

Fischmeister, Florian Ph.S.; Leodolter, Ulrich; Windischberger, Christian; Kasess, Christian H.; Schöpf, Veronika; Moser, Ewald; Bauer, Herbert

2010-01-01

Throughout recent years there has been an increasing interest in studying unconscious visual processes. Such conditions of unawareness are typically achieved by either a sufficient reduction of the stimulus presentation time or visual masking. However, there are growing concerns about the reliability of the presentation devices used. As all these devices show great variability in presentation parameters, the processing of visual stimuli becomes dependent on the display-device, e.g. minimal changes in the physical stimulus properties may have an enormous impact on stimulus processing by the sensory system and on the actual experience of the stimulus. Here we present a custom-built three-way LC-shutter-tachistoscope which allows experimental setups with both, precise and reliable stimulus delivery, and millisecond resolution. This tachistoscope consists of three LCD-projectors equipped with zoom lenses to enable stimulus presentation via a built-in mirror-system onto a back projection screen from an adjacent room. Two high-speed liquid crystal shutters are mounted serially in front of each projector to control the stimulus duration. To verify the intended properties empirically, different sequences of presentation times were performed while changes in optical power were measured using a photoreceiver. The obtained results demonstrate that interfering variabilities in stimulus parameters and stimulus rendering are markedly reduced. Together with the possibility to collect external signals and to send trigger-signals to other devices, this tachistoscope represents a highly flexible and easy to set up research tool not only for the study of unconscious processing in the brain but for vision research in general. PMID:20122963

Is evaluative conditioning really resistant to extinction? Evidence for changes in evaluative judgements without changes in evaluative representations.

PubMed

Gawronski, Bertram; Gast, Anne; De Houwer, Jan

2015-01-01

Evaluative conditioning (EC) is defined as the change in the evaluation of a conditioned stimulus (CS) due to its pairing with a positive or negative unconditioned stimulus (US). Although several individual studies suggest that EC is unaffected by unreinforced presentations of the CS without the US, a recent meta-analysis indicates that EC effects are less pronounced for post-extinction measurements than post-acquisition measurements. The disparity in research findings suggests that extinction of EC may depend on yet unidentified conditions. In an attempt to uncover these conditions, three experiments (N = 784) investigated the influence of unreinforced post-acquisition CS presentations on EC effects resulting from simultaneous versus sequential pairings and pairings with single versus multiple USs. For all four types of CS-US pairings, EC effects on self-reported evaluations were reduced by unreinforced CS presentations, but only when the CSs had been rated after the initial presentation of CS-US pairings. EC effects on an evaluative priming measure remained unaffected by unreinforced CS presentations regardless of whether the CSs had been rated after acquisition. The results suggest that reduced EC effects resulting from unreinforced CS presentations are due to judgement-related processes during the verbal expression of CS evaluations rather than genuine changes in the underlying evaluative representations.

Visual motion direction is represented in population-level neural response as measured by magnetoencephalography.

PubMed

Kaneoke, Y; Urakawa, T; Kakigi, R

2009-05-19

We investigated whether direction information is represented in the population-level neural response evoked by the visual motion stimulus, as measured by magnetoencephalography. Coherent motions with varied speed, varied direction, and different coherence level were presented using random dot kinematography. Peak latency of responses to motion onset was inversely related to speed in all directions, as previously reported, but no significant effect of direction on latency changes was identified. Mutual information entropy (IE) calculated using four-direction response data increased significantly (>2.14) after motion onset in 41.3% of response data and maximum IE was distributed at approximately 20 ms after peak response latency. When response waveforms showing significant differences (by multivariate discriminant analysis) in distribution of the three waveform parameters (peak amplitude, peak latency, and 75% waveform width) with stimulus directions were analyzed, 87 waveform stimulus directions (80.6%) were correctly estimated using these parameters. Correct estimation rate was unaffected by stimulus speed, but was affected by coherence level, even though both speed and coherence affected response amplitude similarly. Our results indicate that speed and direction of stimulus motion are represented in the distinct properties of a response waveform, suggesting that the human brain processes speed and direction separately, at least in part.

Contribution of stimulus attributes to errors in duration and distance judgments--a developmental study.

PubMed

Matsuda, F; Lan, W C; Tanimura, R

1999-02-01

In Matsuda's 1996 study, 4- to 11-yr.-old children (N = 133) watched two cars running on two parallel tracks on a CRT display and judged whether their durations and distances were equal and, if not, which was larger. In the present paper, the relative contributions of the four critical stimulus attributes (whether temporal starting points, temporal stopping points, spatial starting points, and spatial stopping points were the same or different between two cars) to the production of errors were quantitatively estimated based on the data for rates of errors obtained by Matsuda. The present analyses made it possible not only to understand numerically the findings about qualitative characteristics of the critical attributes described by Matsuda, but also to add more detailed findings about them.

The Affective Dimension of Laboratory Dyspnea

PubMed Central

Banzett, Robert B.; Pedersen, Sarah H.; Schwartzstein, Richard M.; Lansing, Robert W.

2008-01-01

Rationale: It is hypothesized that the affective dimension of dyspnea (unpleasantness, emotional response) is not strictly dependent on the intensity of dyspnea. Objectives: We tested the hypothesis that the ratio of immediate unpleasantness (A1) to sensory intensity (SI) varies depending on the type of dyspnea. Methods: Twelve healthy subjects experienced three stimuli: stimulus 1: maximal eucapnic voluntary hyperpnea against inspiratory resistance, requiring 15 times the work of resting breathing; stimulus 2: PetCO2 6.1 mm Hg above resting with ventilation restricted to less than spontaneous breathing; stimulus 3: PetCO2 7.7 mm Hg above resting with ventilation further restricted. After each trial, subjects rated SI, A1, and qualities of dyspnea on the Multidimensional Dyspnea Profile (MDP), a comprehensive instrument tested here for the first time. Measurements and Main Results: Stimulus 1 was always limited by subjects failing to meet a higher ventilation target; none signaled severe discomfort. This evoked work and effort sensations, with relatively low unpleasantness (mean A1/SI = 0.64). Stimulus 2, titrated to produce dyspnea ratings similar to those subjects gave during stimulus 1, evoked air hunger and produced significantly greater unpleasantness (mean A1/SI = 0.95). Stimulus 3, increased until air hunger was intolerable, evoked the highest intensity and unpleasantness ratings and high unpleasantness ratio (mean A1/SI = 1.09). When asked which they would prefer to repeat, all subjects chose stimulus 1. Conclusions: (1) Maximal respiratory work is less unpleasant than moderately intense air hunger in this brief test; (2) unpleasantness of dyspnea can vary independently from perceived intensity, consistent with the prevailing model of pain; (3) separate dimensions of dyspnea can be measured with the MDP. PMID:18369200

[Effect of acoustic stimulus intensity on air-conducted sound elicited ocular vestibular-evoked myogenic potential and cervical vestibular-evoked myogenic potential].

PubMed

Zhang, Rui; Xu, Min; Zhang, Qing; Yang, Yin-Tong; Chen, Yanfei

2014-06-01

To observe the effect of acoustic stimulus intensity on air-conducted sound elicited ocular vestibular- evoked myogenic potential (oVEMP) and cervical vestibular-evoked myogenic potential (cVEMP) in normal young Chinese subjects. Thirty-five normal subjects aged 4-40 years (20.80∓8.89 years), including 16 males and 19 females, were recruited for conventional oVEMP and cVEMP examinations. The responses obtained from each side using 500 Hz tone bursts were divided into 6 groups according to different sound intensities (100, 95, 90, 85, 80 and 75dB nHL). The response rate and normal parameters of each stimulus intensity group were calculated. As the acoustic stimulus intensity decreased, the oVEMP response rate decreased from 100% in both 100 dB nHL and 95dB nHL groups to 97.14% (90 dB nHL), 54.29% (85 dB nHL), 14.29% (80 dB nHL), and 2.86% (75 dB nHL), and the response rate of cVEMP, 100% in both 100 dB nHL and 95dB nHL groups, was lowered to 97.14% (90 dB nHL), 84.29% (85 dB nHL), 38.57% (80 dB nHL) and 8.57% (75 dB nHL). The response rate and the parameters were comparable between 100 and 95 dB nHL groups. As the acoustic stimulus intensity decreases, both oVEMP and cVEMP show decreased response rate and amplitude. For Chinese subjects under 40 years of age, we recommend 95dB nHL as the maximum initial stimulus intensity in VEMPs test.

Rate of Visual Information Pick-Up in Learning Disabled and Normal Boys.

ERIC Educational Resources Information Center

Bryant, Susan K.; And Others

1983-01-01

A span-of-apprehension task and a backward masking technique were combined to allow measurement of the apprehension span of a sample of 34 learning disabled and normal boys about 8 to 13 years old at various time intervals following stimulus presentation. (Author/SW)

The effect of changes in stimulus level on electrically evoked cortical auditory potentials.

PubMed

Kim, Jae-Ryong; Brown, Carolyn J; Abbas, Paul J; Etler, Christine P; O'Brien, Sara

2009-06-01

The purpose of this study was to determine whether the electrically evoked acoustic change complex (EACC) could be used to assess sensitivity to changes in stimulus level in cochlear implant (CI) recipients and to investigate the relationship between EACC amplitude and rate of growth of the N1-P2 onset response with increases in stimulus level. Twelve postlingually deafened adults using Nucleus CI24 CIs participated in this study. Nucleus Implant Communicator (NIC) routines were used to bypass the speech processor and to control the stimulation of the implant directly. The stimulus consisted of an 800 msec burst of a 1000 pps biphasic pulse train. A change in the stimulus level was introduced 400 msec after stimulus onset. Band-pass filtering (1 to 100 Hz) was used to minimize stimulus artifact. Four to six recordings of 50 sweeps were obtained for each condition, and averaged responses were analyzed in the time domain using standard peak picking procedures. Cortical auditory change potentials were recorded from CI users in response to both increases and decreases in stimulation level. The amplitude of the EACC was found to be dependent on the magnitude of the stimulus change. Increases in stimulus level elicited more robust EACC responses than decreases in stimulus level. Also, EACC amplitudes were significantly correlated with the slope of the growth of the onset response. This work describes the effect of change in stimulus level on electrically evoked auditory change potentials in CI users. The amplitude of the EACC was found to be related both to the magnitude of the stimulus change introduced and to the rate of growth of the N1-P2 onset response. To the extent that the EACC reflects processing of stimulus change, it could potentially be a valuable tool for assessing neural processing of the kinds of stimulation patterns produced by a CI. Further studies are needed, however, to determine the relationships between the EACC and psychophysical measures of intensity discrimination in CI recipients.

Effects of age, gender, and stimulus presentation period on visual short-term memory.

PubMed

Kunimi, Mitsunobu

2016-01-01

This study focused on age-related changes in visual short-term memory using visual stimuli that did not allow verbal encoding. Experiment 1 examined the effects of age and the length of the stimulus presentation period on visual short-term memory function. Experiment 2 examined the effects of age, gender, and the length of the stimulus presentation period on visual short-term memory function. The worst memory performance and the largest performance difference between the age groups were observed in the shortest stimulus presentation period conditions. The performance difference between the age groups became smaller as the stimulus presentation period became longer; however, it did not completely disappear. Although gender did not have a significant effect on d' regardless of the presentation period in the young group, a significant gender-based difference was observed for stimulus presentation periods of 500 ms and 1,000 ms in the older group. This study indicates that the decline in visual short-term memory observed in the older group is due to the interaction of several factors.

Variables Affecting Assignment of Occupations to Men and Women.

ERIC Educational Resources Information Center

O'Neill, Patrick

Male and female college students were given a questionnaire containing descriptions of four stimulus persons, with gender of stimulus person varied between groups. Subjects selected any of eight occupations for which the stimulus persons might be suited, and they rated the potential of such persons to be good parents. Traditional "masculinity" of…

An arousing, musically enhanced bird song stimulus mediates circadian rhythm phase advances in dim light.

PubMed

Goel, Namni

2006-09-01

A musically enhanced bird song stimulus presented in the early subjective night phase delays human circadian rhythms. This study determined the phase-shifting effects of the same stimulus in the early subjective day. Eleven subjects (ages 18-63 yr; mean +/- SD: 28.0 +/- 16.6 yr) completed two 4-day laboratory sessions in constant dim light (<20 lux). They received two consecutive presentations of either a 2-h musically enhanced bird song or control stimulus from 0600 to 0800 on the second and third mornings while awake. The 4-day sessions employing either the stimulus or control were counterbalanced. Core body temperature (CBT) was collected throughout the study, and salivary melatonin was obtained every 30 min from 1900 to 2330 on the baseline and poststimulus/postcontrol nights. Dim light melatonin onset and CBT minimum circadian phase before and after stimulus or control presentation was assessed. The musically enhanced bird song stimulus produced significantly larger phase advances of the circadian melatonin (mean +/- SD: 0.87 +/- 0.36 vs. 0.24 +/- 0.22 h) and CBT (1.08 +/- 0.50 vs. 0.43 +/- 0.37 h) rhythms than the control. The stimulus also decreased fatigue and total mood disturbance, suggesting arousing effects. This study shows that a musically enhanced bird song stimulus presented during the early subjective day phase advances circadian rhythms. However, it remains unclear whether the phase shifts are due directly to effects of the stimulus on the clock or are arousal- or dim light-mediated effects. This nonphotic stimulus mediates circadian resynchronization in either the phase advance or delay direction.

Adapting another person's affective state modulates brain potentials to unpleasant pictures.

PubMed

Paul, Sandra; Endrass, Tanja; Kathmann, Norbert; Simon, Daniela

2016-10-01

Emotional processing is influenced by top-down processes such as reappraisal of emotion-inducing events. Besides one's own stimulus appraisal, information from the social environment can be used to modify the stimulus' meaning. This study investigated whether perspective taking changes participants' brain potentials to unpleasant pictures. Event-related potentials (ERPs) were measured while twenty-nine participants evaluated arousal of neutral or negative pictures. Subsequently, they received bogus feedback about another person's picture evaluation. Then, the same picture was presented again and participants were instructed to view the picture from the other person's perspective. Higher bogus- versus self-ratings of picture arousal increased P300 and late positive potential (LPP) amplitudes to unpleasant stimuli, whereas lower bogus- versus self-ratings did not influence ERPs. Thus, perspective taking only modulated ERPs when bogus ratings signaled potential underestimation of arousal. Resulting increases in responsiveness might constitute an adaptive mechanism preparing the organism against harm. Copyright © 2016 Elsevier B.V. All rights reserved.

Object Localization Does Not Imply Awareness of Object Category at the Break of Continuous Flash Suppression

PubMed Central

Kobylka, Florian; Persike, Malte; Meinhardt, Günter

2017-01-01

In continuous flash suppression (CFS), a dynamic noise masker, presented to one eye, suppresses conscious perception of a test stimulus, presented to the other eye, until the suppressed stimulus comes to awareness after few seconds. But what do we see breaking the dominance of the masker in the transition period? We addressed this question with a dual-task in which observers indicated (i) whether the test object was left or right of the fixation mark (localization) and (ii) whether it was a face or a house (categorization). As done recently Stein et al. (2011a), we used two experimental varieties to rule out confounds with decisional strategy. In the terminated mode, stimulus and masker were presented for distinct durations, and the observers were asked to give both judgments at the end of the trial. In the self-paced mode, presentation lasted until the observers responded. In the self-paced mode, b-CFS durations for object categorization were about half a second longer than for object localization. In the terminated mode, correct categorization rates were consistently lower than correct detection rates, measured at five duration intervals ranging up to 2 s. In both experiments we observed an upright face advantage compared to inverted faces and houses, as concurrently reported in b-CFS studies. Our findings reveal that more time is necessary to enable observers judging the nature of the object, compared to judging that there is “something other” than the noise which can be localized, but not recognized. This suggests gradual transitions in the first break of CFS. Further, the results imply that suppression is such that no cues to object identity are conveyed in potential “leaks” of CFS (Gelbard-Sagiv et al., 2016). PMID:28663728

Short-term memory for event duration: modality specificity and goal dependency.

PubMed

Takahashi, Kohske; Watanabe, Katsumi

2012-11-01

Time perception is involved in various cognitive functions. This study investigated the characteristics of short-term memory for event duration by examining how the length of the retention period affects inter- and intramodal duration judgment. On each trial, a sample stimulus was followed by a comparison stimulus, after a variable delay period (0.5-5 s). The sample and comparison stimuli were presented in the visual or auditory modality. The participants determined whether the comparison stimulus was longer or shorter than the sample stimulus. The distortion pattern of subjective duration during the delay period depended on the sensory modality of the comparison stimulus but was not affected by that of the sample stimulus. When the comparison stimulus was visually presented, the retained duration of the sample stimulus was shortened as the delay period increased. Contrarily, when the comparison stimulus was presented in the auditory modality, the delay period had little to no effect on the retained duration. Furthermore, whenever the participants did not know the sensory modality of the comparison stimulus beforehand, the effect of the delay period disappeared. These results suggest that the memory process for event duration is specific to sensory modality and that its performance is determined depending on the sensory modality in which the retained duration will be used subsequently.

Psychophysiological effects of audiovisual stimuli during cycle exercise.

PubMed

Barreto-Silva, Vinícius; Bigliassi, Marcelo; Chierotti, Priscila; Altimari, Leandro R

2018-05-01

Immersive environments induced by audiovisual stimuli are hypothesised to facilitate the control of movements and ameliorate fatigue-related symptoms during exercise. The objective of the present study was to investigate the effects of pleasant and unpleasant audiovisual stimuli on perceptual and psychophysiological responses during moderate-intensity exercises performed on an electromagnetically braked cycle ergometer. Twenty young adults were administered three experimental conditions in a randomised and counterbalanced order: unpleasant stimulus (US; e.g. images depicting laboured breathing); pleasant stimulus (PS; e.g. images depicting pleasant emotions); and neutral stimulus (NS; e.g. neutral facial expressions). The exercise had 10 min of duration (2 min of warm-up + 6 min of exercise + 2 min of warm-down). During all conditions, the rate of perceived exertion and heart rate variability were monitored to further understanding of the moderating influence of audiovisual stimuli on perceptual and psychophysiological responses, respectively. The results of the present study indicate that PS ameliorated fatigue-related symptoms and reduced the physiological stress imposed by the exercise bout. Conversely, US increased the global activity of the autonomic nervous system and increased exertional responses to a greater degree when compared to PS. Accordingly, audiovisual stimuli appear to induce a psychophysiological response in which individuals visualise themselves within the story presented in the video. In such instances, individuals appear to copy the behaviour observed in the videos as if the situation was real. This mirroring mechanism has the potential to up-/down-regulate the cardiac work as if in fact the exercise intensities were different in each condition.

Aging and the rate of visual information processing.

PubMed

Guest, Duncan; Howard, Christina J; Brown, Louise A; Gleeson, Harriet

2015-01-01

Multiple methods exist for measuring how age influences the rate of visual information processing. The most advanced methods model the processing dynamics in a task in order to estimate processing rates independently of other factors that might be influenced by age, such as overall performance level and the time at which processing onsets. However, such modeling techniques have produced mixed evidence for age effects. Using a time-accuracy function (TAF) analysis, Kliegl, Mayr, and Krampe (1994) showed clear evidence for age effects on processing rate. In contrast, using the diffusion model to examine the dynamics of decision processes, Ratcliff and colleagues (e.g., Ratcliff, Thapar, & McKoon, 2006) found no evidence for age effects on processing rate across a range of tasks. Examination of these studies suggests that the number of display stimuli might account for the different findings. In three experiments we measured the precision of younger and older adults' representations of target stimuli after different amounts of stimulus exposure. A TAF analysis found little evidence for age differences in processing rate when a single stimulus was presented (Experiment 1). However, adding three nontargets to the display resulted in age-related slowing of processing (Experiment 2). Similar slowing was observed when simply presenting two stimuli and using a post-cue to indicate the target (Experiment 3). Although there was some interference from distracting objects and from previous responses, these age-related effects on processing rate seem to reflect an age-related difficulty in processing multiple objects, particularly when encoding them into visual working memory.

Transfer of dimensional associability in human contingency learning.

PubMed

Kattner, Florian; Green, C Shawn

2016-01-01

Several studies have demonstrated processing advantages for stimuli that were experienced to be reliable predictors of an outcome relative to other stimuli. The present study tested whether such increases in associability apply at the level of entire stimulus dimensions (as suggested by Sutherland & Mackintosh, 1971). In 4 experiments, participants had to learn associations between Gabor gratings and particular responses. In a first experiment, some gratings were more predictive of the response than other gratings, whereas in 3 subsequent experiments, one stimulus dimension (i.e., either the orientation or spatial frequency of the grating) was more predictive than the other dimension. In contrast to the learned predictiveness of individual gratings (Experiment 1), dimensional predictiveness did not affect the subsequent rate of learning (Experiments 2 and 3), suggesting changes in the associability of specific stimuli, but not of stimulus dimensions. Moreover, greater transfer of predictiveness was found in all experiments when particular stimulus values of the test discrimination did not lie between the previously relevant stimuli. In Experiment 4, an increased learning rate was found for discriminations along the previously predictive dimension compared with a dimension that was indicative of uncertainty, but again the transfer was more pronounced for specific stimuli that were compatible with the previously learned discrimination. Taken together, the results imply that a transfer of associability typically applies to individual stimuli and depends on how the transfer stimuli relate to those stimuli that individuals previously learned to attend. (c) 2016 APA, all rights reserved).

SSVEP-BCI implementation for 37-40 Hz frequency range.

PubMed

Müller, Sandra Mara Torres; Diez, Pablo F; Bastos-Filho, Teodiano Freire; Sarcinelli-Filho, Mário; Mut, Vicente; Laciar, Eric

2011-01-01

This work presents a Brain-Computer Interface (BCI) based on Steady State Visual Evoked Potentials (SSVEP), using higher stimulus frequencies (>30 Hz). Using a statistical test and a decision tree, the real-time EEG registers of six volunteers are analyzed, with the classification result updated each second. The BCI developed does not need any kind of settings or adjustments, which makes it more general. Offline results are presented, which corresponds to a correct classification rate of up to 99% and a Information Transfer Rate (ITR) of up to 114.2 bits/min.

Neural evidence that inhibition is linked to the affective devaluation of distractors that match the contents of working memory.

PubMed

De Vito, David; Al-Aidroos, Naseem; Fenske, Mark J

2017-05-01

Stimuli appearing as visual distractors subsequently receive more negative affective evaluations than novel items or prior targets of attention. Leading accounts question whether this distractor devaluation effect occurs through evaluative codes that become associated with distractors as a mere artefact of attention-task instructions, or through affective consequences of attentional inhibition when applied to prevent distractor interference. Here we test opposing predictions arising from the evaluative-coding and devaluation-by-inhibition hypotheses using an electrophysiological marker of attentional inhibition in a task that requires participants to avoid interference from abstract-shape distractors presented while maintaining a uniquely-colored stimulus in memory. Consistent with prior research, distractors that matched the colour of the stimulus being held in memory elicited a Pd component of the event-related potential waveform, indicating that their processing was being actively suppressed. Subsequent affective evaluations revealed that memory-matching distractors also received more negative ratings than non-matching distractors or previously-unseen shapes. Moreover, Pd magnitude was greater on trials in which the memory-matching distractors were later rated negatively than on trials preceding positive ratings. These results support the devaluation-by-inhibition hypothesis and strongly suggest that fluctuations in stimulus inhibition are closely associated with subsequent affective evaluations. In contrast, none of the evaluative-coding based predictions were confirmed. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selective attention to affective value alters how the brain processes olfactory stimuli.

PubMed

Rolls, Edmund T; Grabenhorst, Fabian; Margot, Christian; da Silva, Maria A A P; Velazco, Maria Ines

2008-10-01

How does selective attention to affect influence sensory processing? In a functional magnetic resonance imaging investigation, when subjects were instructed to remember and rate the pleasantness of a jasmine odor, activations were greater in the medial orbito-frontal and pregenual cingulate cortex than when subjects were instructed to remember and rate the intensity of the odor. When the subjects were instructed to remember and rate the intensity, activations were greater in the inferior frontal gyrus. These top-down effects occurred not only during odor delivery but started in a preparation period after the instruction before odor delivery, and continued after termination of the odor in a short-term memory period. Thus, depending on the context in which odors are presented and whether affect is relevant, the brain prepares itself, responds to, and remembers an odor differently. These findings show that when attention is paid to affective value, the brain systems engaged to prepare for, represent, and remember a sensory stimulus are different from those engaged when attention is directed to the physical properties of a stimulus such as its intensity. This differential biasing of brain regions engaged in processing a sensory stimulus depending on whether the cognitive demand is for affect-related versus more sensory-related processing may be an important aspect of cognition and attention. This has many implications for understanding the effects not only of olfactory but also of other sensory stimuli.

Order of Stimulus Presentation Influences Children's Acquisition in Receptive Identification Tasks

ERIC Educational Resources Information Center

Petursdottir, Anna Ingeborg; Aguilar, Gabriella

2016-01-01

Receptive identification is usually taught in matching-to-sample format, which entails the presentation of an auditory sample stimulus and several visual comparison stimuli in each trial. Conflicting recommendations exist regarding the order of stimulus presentation in matching-to-sample trials. The purpose of this study was to compare acquisition…

Transformation of the neural code for tactile detection from thalamus to cortex.

PubMed

Vázquez, Yuriria; Salinas, Emilio; Romo, Ranulfo

2013-07-09

To understand how sensory-driven neural activity gives rise to perception, it is essential to characterize how various relay stations in the brain encode stimulus presence. Neurons in the ventral posterior lateral (VPL) nucleus of the somatosensory thalamus and in primary somatosensory cortex (S1) respond to vibrotactile stimulation with relatively slow modulations (∼100 ms) of their firing rate. In addition, faster modulations (∼10 ms) time-locked to the stimulus waveform are observed in both areas, but their contribution to stimulus detection is unknown. Furthermore, it is unclear whether VPL and S1 neurons encode stimulus presence with similar accuracy and via the same response features. To address these questions, we recorded single neurons while trained monkeys judged the presence or absence of a vibrotactile stimulus of variable amplitude, and their activity was analyzed with a unique decoding method that is sensitive to the time scale of the firing rate fluctuations. We found that the maximum detection accuracy of single neurons is similar in VPL and S1. However, VPL relies more heavily on fast rate modulations than S1, and as a consequence, the neural code in S1 is more tolerant: its performance degrades less when the readout method or the time scale of integration is suboptimal. Therefore, S1 neurons implement a more robust code, one less sensitive to the temporal integration window used to infer stimulus presence downstream. The differences between VPL and S1 responses signaling the appearance of a stimulus suggest a transformation of the neural code from thalamus to cortex.

An Examination of Stimulus Control in Fluency-Based Strategies: SAFMEDS and Generalization

ERIC Educational Resources Information Center

Meindl, James N.; Ivy, Jonathan W.; Miller, Neal; Neef, Nancy A.; Williamson, Robert L.

2013-01-01

Fluency-based strategies such as Say All Fast a Minute Each Day Shuffled (SAFMEDS) effectively promote fluent responding (i.e., high rate and accuracy). It is possible, however, that the stimulus control developed through these activities inhibits stimulus generalization. We investigated this concern in a two-part study with college students.…

BOLDSync: a MATLAB-based toolbox for synchronized stimulus presentation in functional MRI.

PubMed

Joshi, Jitesh; Saharan, Sumiti; Mandal, Pravat K

2014-02-15

Precise and synchronized presentation of paradigm stimuli in functional magnetic resonance imaging (fMRI) is central to obtaining accurate information about brain regions involved in a specific task. In this manuscript, we present a new MATLAB-based toolbox, BOLDSync, for synchronized stimulus presentation in fMRI. BOLDSync provides a user friendly platform for design and presentation of visual, audio, as well as multimodal audio-visual (AV) stimuli in functional imaging experiments. We present simulation experiments that demonstrate the millisecond synchronization accuracy of BOLDSync, and also illustrate the functionalities of BOLDSync through application to an AV fMRI study. BOLDSync gains an advantage over other available proprietary and open-source toolboxes by offering a user friendly and accessible interface that affords both precision in stimulus presentation and versatility across various types of stimulus designs and system setups. BOLDSync is a reliable, efficient, and versatile solution for synchronized stimulus presentation in fMRI study. Copyright © 2013 Elsevier B.V. All rights reserved.

Square or sine: finding a waveform with high success rate of eliciting SSVEP.

PubMed

Teng, Fei; Chen, Yixin; Choong, Aik Min; Gustafson, Scott; Reichley, Christopher; Lawhead, Pamela; Waddell, Dwight

2011-01-01

Steady state visual evoked potential (SSVEP) is the brain's natural electrical potential response for visual stimuli at specific frequencies. Using a visual stimulus flashing at some given frequency will entrain the SSVEP at the same frequency, thereby allowing determination of the subject's visual focus. The faster an SSVEP is identified, the higher information transmission rate the system achieves. Thus, an effective stimulus, defined as one with high success rate of eliciting SSVEP and high signal-noise ratio, is desired. Also, researchers observed that harmonic frequencies often appear in the SSVEP at a reduced magnitude. Are the harmonics in the SSVEP elicited by the fundamental stimulating frequency or by the artifacts of the stimuli? In this paper, we compare the SSVEP responses of three periodic stimuli: square wave (with different duty cycles), triangle wave, and sine wave to find an effective stimulus. We also demonstrate the connection between the strength of the harmonics in SSVEP and the type of stimulus.

Multiple cues add up in defining a figure on a ground.

PubMed

Devinck, Frédéric; Spillmann, Lothar

2013-01-25

We studied the contribution of multiple cues to figure-ground segregation. Convexity, symmetry, and top-down polarity (henceforth called wide base) were used as cues. Single-cue displays as well as ambiguous stimulus patterns containing two or three cues were presented. Error rate (defined by responses to uncued stimuli) and reaction time were used to quantify the figural strength of a given cue. In the first experiment, observers were asked to report which of two regions, left or right, appeared as foreground figure. Error rate did not benefit from adding additional cues if convexity was present, suggesting that responses were based on convexity as the predominant figural determinant. However, reaction time became shorter with additional cues even if convexity was present. For example, when symmetry and wide base were added, figure-ground segregation was facilitated. In a second experiment, stimulus patterns were exposed for 150ms to rule out eye movements. Results were similar to those found in the first experiment. Both experiments suggest that under the conditions of our experiment figure-ground segregation is perceived more readily, when several cues cooperate in defining the figure. Copyright © 2012 Elsevier Ltd. All rights reserved.

Stimulus information stored in lasting active and hidden network states is destroyed by network bursts

PubMed Central

Dranias, Mark R.; Westover, M. Brandon; Cash, Sidney; VanDongen, Antonius M. J.

2015-01-01

In both humans and animals brief synchronizing bursts of epileptiform activity known as interictal epileptiform discharges (IEDs) can, even in the absence of overt seizures, cause transient cognitive impairments (TCI) that include problems with perception or short-term memory. While no evidence from single units is available, it has been assumed that IEDs destroy information represented in neuronal networks. Cultured neuronal networks are a model for generic cortical microcircuits, and their spontaneous activity is characterized by the presence of synchronized network bursts (SNBs), which share a number of properties with IEDs, including the high degree of synchronization and their spontaneous occurrence in the absence of an external stimulus. As a model approach to understanding the processes underlying IEDs, optogenetic stimulation and multielectrode array (MEA) recordings of cultured neuronal networks were used to study whether stimulus information represented in these networks survives SNBs. When such networks are optically stimulated they encode and maintain stimulus information for as long as one second. Experiments involved recording the network response to a single stimulus and trials where two different stimuli were presented sequentially, akin to a paired pulse trial. We broke the sequential stimulus trials into encoding, delay and readout phases and found that regardless of which phase the SNB occurs, stimulus-specific information was impaired. SNBs were observed to increase the mean network firing rate, but this did not translate monotonically into increases in network entropy. It was found that the more excitable a network, the more stereotyped its response was during a network burst. These measurements speak to whether SNBs are capable of transmitting information in addition to blocking it. These results are consistent with previous reports and provide baseline predictions concerning the neural mechanisms by which IEDs might cause TCI. PMID:25755638

Subliminal stimulation and somatosensory signal detection.

PubMed

Ferrè, Elisa Raffaella; Sahani, Maneesh; Haggard, Patrick

2016-10-01

Only a small fraction of sensory signals is consciously perceived. The brain's perceptual systems may include mechanisms of feedforward inhibition that protect the cortex from subliminal noise, thus reserving cortical capacity and conscious awareness for significant stimuli. Here we provide a new view of these mechanisms based on signal detection theory, and gain control. We demonstrated that subliminal somatosensory stimulation decreased sensitivity for the detection of a subsequent somatosensory input, largely due to increased false alarm rates. By delivering the subliminal somatosensory stimulus and the to-be-detected somatosensory stimulus to different digits of the same hand, we show that this effect spreads across the sensory surface. In addition, subliminal somatosensory stimulation tended to produce an increased probability of responding "yes", whether the somatosensory stimulus was present or not. Our results suggest that subliminal stimuli temporarily reduce input gain, avoiding excessive responses to further small inputs. This gain control may be automatic, and may precede discriminative classification of inputs into signals or noise. Crucially, we found that subliminal inputs influenced false alarm rates only on blocks where the to-be-detected stimuli were present, and not on pre-test control blocks where they were absent. Participants appeared to adjust their perceptual criterion according to a statistical distribution of stimuli in the current context, with the presence of supraliminal stimuli having an important role in the criterion-setting process. These findings clarify the cognitive mechanisms that reserve conscious perception for salient and important signals. Copyright © 2016 Elsevier B.V. All rights reserved.

Visual adaptation and novelty responses in the superior colliculus

PubMed Central

Boehnke, Susan E.; Berg, David J.; Marino, Robert M.; Baldi, Pierre F.; Itti, Laurent; Munoz, Douglas P.

2011-01-01

The brain's ability to ignore repeating, often redundant, information while enhancing novel information processing is paramount to survival. When stimuli are repeatedly presented, the response of visually-sensitive neurons decreases in magnitude, i.e. neurons adapt or habituate, although the mechanism is not yet known. We monitored activity of visual neurons in the superior colliculus (SC) of rhesus monkeys who actively fixated while repeated visual events were presented. We dissociated adaptation from habituation as mechanisms of the response decrement by using a Bayesian model of adaptation, and by employing a paradigm including rare trials that included an oddball stimulus that was either brighter or dimmer. If the mechanism is adaptation, response recovery should be seen only for the brighter stimulus; if habituation, response recovery (‘dishabituation’) should be seen for both the brighter and dimmer stimulus. We observed a reduction in the magnitude of the initial transient response and an increase in response onset latency with stimulus repetition for all visually responsive neurons in the SC. Response decrement was successfully captured by the adaptation model which also predicted the effects of presentation rate and rare luminance changes. However, in a subset of neurons with sustained activity to visual stimuli, a novelty signal akin to dishabituation was observed late in the visual response profile to both brighter and dimmer stimuli and was not captured by the model. This suggests that SC neurons integrate both rapidly discounted information about repeating stimuli and novelty information about oddball events, to support efficient selection in a cluttered dynamic world. PMID:21864319

Thermoresponsive release of viable microfiltrated Circulating Tumor Cells (CTCs) for precision medicine applications

PubMed Central

Ao, Zheng; Parasido, Erika; Rawal, Siddarth; Williams, Anthony; Schlegel, Richard; Liu, Stephen; Albanese, Chris; Cote, Richard J.; Agarwal, Ashutosh; Datar, Ram H.

2015-01-01

Stimulus responsive release of Circulating Tumor Cells (CTCs), with high recovery rates from their capture platform, is highly desirable for off-chip analyses. Here, we present a temperature responsive polymer coating method to achieve both release as well as culture of viable CTCs captured from patient blood samples. PMID:26426331

How IRT Can Solve Problems of Ipsative Data in Forced-Choice Questionnaires

ERIC Educational Resources Information Center

Brown, Anna; Maydeu-Olivares, Alberto

2013-01-01

In multidimensional forced-choice (MFC) questionnaires, items measuring different attributes are presented in blocks, and participants have to rank order the items within each block (fully or partially). Such comparative formats can reduce the impact of numerous response biases often affecting single-stimulus items (aka rating or Likert scales).…

Subliminal cues bias perception of facial affect in patients with social phobia: evidence for enhanced unconscious threat processing

PubMed Central

Jusyte, Aiste; Schönenberg, Michael

2014-01-01

Socially anxious individuals have been shown to exhibit altered processing of facial affect, especially expressions signaling threat. Enhanced unaware processing has been suggested an important mechanism which may give rise to anxious conscious cognition and behavior. This study investigated whether individuals with social anxiety disorder (SAD) are perceptually more vulnerable to the biasing effects of subliminal threat cues compared to healthy controls. In a perceptual judgment task, 23 SAD and 23 matched control participants were asked to rate the affective valence of parametrically manipulated affective expressions ranging from neutral to angry. Each trial was preceded by subliminal presentation of an angry/neutral cue. The SAD group tended to rate target faces as “angry” when the preceding subliminal stimulus was angry vs. neutral, while healthy participants were not biased by the subliminal stimulus presentation. The perceptual bias in SAD was also associated with higher reaction time latencies in the subliminal angry cue condition. The results provide further support for enhanced unconscious threat processing in SAD individuals. The implications for etiology, maintenance, and treatment of SAD are discussed. PMID:25136307

Subliminal cues bias perception of facial affect in patients with social phobia: evidence for enhanced unconscious threat processing.

PubMed

Jusyte, Aiste; Schönenberg, Michael

2014-01-01

Socially anxious individuals have been shown to exhibit altered processing of facial affect, especially expressions signaling threat. Enhanced unaware processing has been suggested an important mechanism which may give rise to anxious conscious cognition and behavior. This study investigated whether individuals with social anxiety disorder (SAD) are perceptually more vulnerable to the biasing effects of subliminal threat cues compared to healthy controls. In a perceptual judgment task, 23 SAD and 23 matched control participants were asked to rate the affective valence of parametrically manipulated affective expressions ranging from neutral to angry. Each trial was preceded by subliminal presentation of an angry/neutral cue. The SAD group tended to rate target faces as "angry" when the preceding subliminal stimulus was angry vs. neutral, while healthy participants were not biased by the subliminal stimulus presentation. The perceptual bias in SAD was also associated with higher reaction time latencies in the subliminal angry cue condition. The results provide further support for enhanced unconscious threat processing in SAD individuals. The implications for etiology, maintenance, and treatment of SAD are discussed.

Language performance and auditory evoked fields in 2- to 5-year-old children.

PubMed

Yoshimura, Yuko; Kikuchi, Mitsuru; Shitamichi, Kiyomi; Ueno, Sanae; Remijn, Gerard B; Haruta, Yasuhiro; Oi, Manabu; Munesue, Toshio; Tsubokawa, Tsunehisa; Higashida, Haruhiro; Minabe, Yoshio

2012-02-01

Language development progresses at a dramatic rate in preschool children. As rapid temporal processing of speech signals is important in daily colloquial environments, we performed magnetoencephalography (MEG) to investigate the linkage between speech-evoked responses during rapid-rate stimulus presentation (interstimulus interval < 1 s) and language performance in 2- to 5-year-old children (n = 59). Our results indicated that syllables with this short stimulus interval evoked detectable P50m, but not N100m, in most participants, indicating a marked influence of longer neuronal refractory period for stimulation. The results of equivalent dipole estimation showed that the intensity of the P50m component in the left hemisphere was positively correlated with language performance (conceptual inference ability). The observed positive correlations were suggested to reflect the maturation of synaptic organisation or axonal maturation and myelination underlying the acquisition of linguistic abilities. The present study is among the first to use MEG to study brain maturation pertaining to language abilities in preschool children. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

The importance of a compound stimulus in conditioned drug-seeking behavior following one week of extinction from self-administered cocaine in rats.

PubMed

See, R E; Grimm, J W; Kruzich, P J; Rustay, N

1999-11-01

Previous studies have demonstrated that conditioned stimuli can increase responding on a drug-associated lever after extinction from drug self-administration. The present study investigated singular stimuli (tone or light) or a compound stimulus (tone + light) for their ability to increase extinguished responding following chronic cocaine self-administration. Rats self-administered cocaine for 2 weeks on a fixed ratio (FR1) schedule of reinforcement, in which lever responding resulted in varied presentation of a tone, light, or tone + light combination. The rats were then exposed to 1 week of daily extinction sessions. Presentation of the tone + light on day 8 of extinction in the absence of cocaine reinforcement resulted in a significant increase in responding, while either stimulus component alone was much weaker or failed to produce any changes from extinction rates of responding. In addition, changing the duration of the single elements of the compound did not affect the magnitude of increased responding to the compound. Following three final extinction sessions, robust lever responding for cocaine infusions on day 12 of extinction was seen across all groups. These findings suggest that compound stimuli may be critical to fully activate drug-seeking behavior in conditions of craving and relapse following prolonged extinction.

Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin.

PubMed

Todd, N P M; Govender, S; Colebatch, J G

2016-11-01

Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

A Recurrent Network Model of Somatosensory Parametric Working Memory in the Prefrontal Cortex

PubMed Central

Miller, Paul; Brody, Carlos D; Romo, Ranulfo; Wang, Xiao-Jing

2015-01-01

A parametric working memory network stores the information of an analog stimulus in the form of persistent neural activity that is monotonically tuned to the stimulus. The family of persistent firing patterns with a continuous range of firing rates must all be realizable under exactly the same external conditions (during the delay when the transient stimulus is withdrawn). How this can be accomplished by neural mechanisms remains an unresolved question. Here we present a recurrent cortical network model of irregularly spiking neurons that was designed to simulate a somatosensory working memory experiment with behaving monkeys. Our model reproduces the observed positively and negatively monotonic persistent activity, and heterogeneous tuning curves of memory activity. We show that fine-tuning mathematically corresponds to a precise alignment of cusps in the bifurcation diagram of the network. Moreover, we show that the fine-tuned network can integrate stimulus inputs over several seconds. Assuming that such time integration occurs in neural populations downstream from a tonically persistent neural population, our model is able to account for the slow ramping-up and ramping-down behaviors of neurons observed in prefrontal cortex. PMID:14576212

The Differential Effect of Skin Color on Attractiveness, Personality Evaluations, and Perceived Life Success of African Americans

ERIC Educational Resources Information Center

Wade, T. Joel; Bielitz, Sara

2005-01-01

Skin color in relation to perceived attractiveness, personality ratings, and perceived life success of African Americans was investigated in a 2 (sex of participant) 2 (skin color of stimulus person) 2 (sex of stimulus person) design. Based on prior research, Skin Color Sex of Stimulus Person and Sex of Participant Skin Color interactions were…

Stimulus Effects on Local Preference: Stimulus-Response Contingencies, Stimulus-Food Pairing, and Stimulus-Food Correlation

ERIC Educational Resources Information Center

Davison, Michael; Baum, William M.

2010-01-01

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…

Eccentricity effects in vision and attention.

PubMed

Staugaard, Camilla Funch; Petersen, Anders; Vangkilde, Signe

2016-11-01

Stimulus eccentricity affects visual processing in multiple ways. Performance on a visual task is often better when target stimuli are presented near or at the fovea compared to the retinal periphery. For instance, reaction times and error rates are often reported to increase with increasing eccentricity. Such findings have been interpreted as purely visual, reflecting neurophysiological differences in central and peripheral vision, as well as attentional, reflecting a central bias in the allocation of attentional resources. Other findings indicate that in some cases, information from the periphery is preferentially processed. Specifically, it has been suggested that visual processing speed increases with increasing stimulus eccentricity, and that this positive correlation is reduced, but not eliminated, when the amount of cortex activated by a stimulus is kept constant by magnifying peripheral stimuli (Carrasco et al., 2003). In this study, we investigated effects of eccentricity on visual attentional capacity with and without magnification, using computational modeling based on Bundesen's (1990) theory of visual attention. Our results suggest a general decrease in attentional capacity with increasing stimulus eccentricity, irrespective of magnification. We discuss these results in relation to the physiology of the visual system, the use of different paradigms for investigating visual perception across the visual field, and the use of different stimulus materials (e.g. Gabor patches vs. letters). Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

Effects of auditory information on self-motion perception during simultaneous presentation of visual shearing motion

PubMed Central

Tanahashi, Shigehito; Ashihara, Kaoru; Ujike, Hiroyasu

2015-01-01

Recent studies have found that self-motion perception induced by simultaneous presentation of visual and auditory motion is facilitated when the directions of visual and auditory motion stimuli are identical. They did not, however, examine possible contributions of auditory motion information for determining direction of self-motion perception. To examine this, a visual stimulus projected on a hemisphere screen and an auditory stimulus presented through headphones were presented separately or simultaneously, depending on experimental conditions. The participant continuously indicated the direction and strength of self-motion during the 130-s experimental trial. When the visual stimulus with a horizontal shearing rotation and the auditory stimulus with a horizontal one-directional rotation were presented simultaneously, the duration and strength of self-motion perceived in the opposite direction of the auditory rotation stimulus were significantly longer and stronger than those perceived in the same direction of the auditory rotation stimulus. However, the auditory stimulus alone could not sufficiently induce self-motion perception, and if it did, its direction was not consistent within each experimental trial. We concluded that auditory motion information can determine perceived direction of self-motion during simultaneous presentation of visual and auditory motion information, at least when visual stimuli moved in opposing directions (around the yaw-axis). We speculate that the contribution of auditory information depends on the plausibility and information balance of visual and auditory information. PMID:26113828

Statistical context shapes stimulus-specific adaptation in human auditory cortex

PubMed Central

Henry, Molly J.; Fromboluti, Elisa Kim; McAuley, J. Devin

2015-01-01

Stimulus-specific adaptation is the phenomenon whereby neural response magnitude decreases with repeated stimulation. Inconsistencies between recent nonhuman animal recordings and computational modeling suggest dynamic influences on stimulus-specific adaptation. The present human electroencephalography (EEG) study investigates the potential role of statistical context in dynamically modulating stimulus-specific adaptation by examining the auditory cortex-generated N1 and P2 components. As in previous studies of stimulus-specific adaptation, listeners were presented with oddball sequences in which the presentation of a repeated tone was infrequently interrupted by rare spectral changes taking on three different magnitudes. Critically, the statistical context varied with respect to the probability of small versus large spectral changes within oddball sequences (half of the time a small change was most probable; in the other half a large change was most probable). We observed larger N1 and P2 amplitudes (i.e., release from adaptation) for all spectral changes in the small-change compared with the large-change statistical context. The increase in response magnitude also held for responses to tones presented with high probability, indicating that statistical adaptation can overrule stimulus probability per se in its influence on neural responses. Computational modeling showed that the degree of coadaptation in auditory cortex changed depending on the statistical context, which in turn affected stimulus-specific adaptation. Thus the present data demonstrate that stimulus-specific adaptation in human auditory cortex critically depends on statistical context. Finally, the present results challenge the implicit assumption of stationarity of neural response magnitudes that governs the practice of isolating established deviant-detection responses such as the mismatch negativity. PMID:25652920

Short-term memory in zebrafish (Danio rerio).

PubMed

Jia, Jason; Fernandes, Yohaan; Gerlai, Robert

2014-08-15

Learning and memory represent perhaps the most complex behavioral phenomena. Although their underlying mechanisms have been extensively analyzed, only a fraction of the potential molecular components have been identified. The zebrafish has been proposed as a screening tool with which mechanisms of complex brain functions may be systematically uncovered. However, as a relative newcomer in behavioral neuroscience, the zebrafish has not been well characterized for its cognitive and mnemonic features, thus learning and/or memory screens with adults have not been feasible. Here we study short-term memory of adult zebrafish. We show animated images of conspecifics (the stimulus) to the experimental subject during 1 min intervals on ten occasions separated by different (2, 4, 8 or 16 min long) inter-stimulus intervals (ISI), a between subject experimental design. We quantify the distance of the subject from the image presentation screen during each stimulus presentation interval, during each of the 1-min post-stimulus intervals immediately following the stimulus presentations and during each of the 1-min intervals furthest away from the last stimulus presentation interval and just before the next interval (pre-stimulus interval), respectively. Our results demonstrate significant retention of short-term memory even in the longest ISI group but suggest no acquisition of reference memory. Because in the employed paradigm both stimulus presentation and behavioral response quantification is computer automated, we argue that high-throughput screening for drugs or mutations that alter short-term memory performance of adult zebrafish is now becoming feasible. Copyright © 2014 Elsevier B.V. All rights reserved.

The Dynamics and Neural Correlates of Audio-Visual Integration Capacity as Determined by Temporal Unpredictability, Proactive Interference, and SOA.

PubMed

Wilbiks, Jonathan M P; Dyson, Benjamin J

2016-01-01

Over 5 experiments, we challenge the idea that the capacity of audio-visual integration need be fixed at 1 item. We observe that the conditions under which audio-visual integration is most likely to exceed 1 occur when stimulus change operates at a slow rather than fast rate of presentation and when the task is of intermediate difficulty such as when low levels of proactive interference (3 rather than 8 interfering visual presentations) are combined with the temporal unpredictability of the critical frame (Experiment 2), or, high levels of proactive interference are combined with the temporal predictability of the critical frame (Experiment 4). Neural data suggest that capacity might also be determined by the quality of perceptual information entering working memory. Experiment 5 supported the proposition that audio-visual integration was at play during the previous experiments. The data are consistent with the dynamic nature usually associated with cross-modal binding, and while audio-visual integration capacity likely cannot exceed uni-modal capacity estimates, performance may be better than being able to associate only one visual stimulus with one auditory stimulus.

The Dynamics and Neural Correlates of Audio-Visual Integration Capacity as Determined by Temporal Unpredictability, Proactive Interference, and SOA

PubMed Central

Wilbiks, Jonathan M. P.; Dyson, Benjamin J.

2016-01-01

Over 5 experiments, we challenge the idea that the capacity of audio-visual integration need be fixed at 1 item. We observe that the conditions under which audio-visual integration is most likely to exceed 1 occur when stimulus change operates at a slow rather than fast rate of presentation and when the task is of intermediate difficulty such as when low levels of proactive interference (3 rather than 8 interfering visual presentations) are combined with the temporal unpredictability of the critical frame (Experiment 2), or, high levels of proactive interference are combined with the temporal predictability of the critical frame (Experiment 4). Neural data suggest that capacity might also be determined by the quality of perceptual information entering working memory. Experiment 5 supported the proposition that audio-visual integration was at play during the previous experiments. The data are consistent with the dynamic nature usually associated with cross-modal binding, and while audio-visual integration capacity likely cannot exceed uni-modal capacity estimates, performance may be better than being able to associate only one visual stimulus with one auditory stimulus. PMID:27977790

Pavlovian conditioning and cumulative reinforcement rate.

PubMed

Harris, Justin A; Patterson, Angela E; Gharaei, Saba

2015-04-01

In 5 experiments using delay conditioning of magazine approach with rats, reinforcement rate was varied either by manipulating the mean interval between onset of the conditioned stimulus (CS) and unconditioned stimulus (US) or by manipulating the proportion of CS presentations that ended with the US (trial-based reinforcement rate). Both manipulations influenced the acquisition of responding. In each experiment, a specific comparison was made between 2 CSs that differed in their mean CS-US interval and in their trial-based reinforcement rate, such that the cumulative reinforcement rate-the cumulative duration of the CS between reinforcements-was the same for the 2 CSs. For example, a CS reinforced on 100% of trials with a mean CS-US interval of 60 s was compared with a CS reinforced on 33% of trials and a mean duration of 20 s. Across the 5 experiments, conditioning was virtually identical for the 2 CSs with matched cumulative reinforcement rate. This was true as long as the timing of the US was unpredictable and, thus, response rates were uniform across the length of the CS. We conclude that the effects of CS-US interval and of trial-based reinforcement rate are reducible entirely to their common effect on cumulative reinforcement rate. We discuss the implications of this for rate-based, trial-based, and real-time associative models of conditioning. (c) 2015 APA, all rights reserved).

Age Trends in Stimulus Overselectivity

ERIC Educational Resources Information Center

McHugh, Louise; Reed, Phil

2007-01-01

Stimulus overselectivity refers to the phenomenon whereby stimulus control over behavior is exerted only by a limited subset of the total number of stimuli present during discrimination learning. It often is displayed by individuals with autistic spectrum disorders or learning disabilities, but is not exclusive to those groups. The present studies…

Discriminative-Stimulus, Subject-rated and Physiological Effects of Methamphetamine in Humans Pretreated with Aripiprazole

PubMed Central

Sevak, Rajkumar J.; Vansickel, Andrea R.; Stoops, William W.; Glaser, Paul E. A.; Hays, Lon R.; Rush, Craig R.

2013-01-01

Methamphetamine is thought to produce its behavioral effects by releasing dopamine (DA), serotonin (5-HT) and norepinephrine. Results from animal studies support this notion, while results from human laboratory studies have not consistently demonstrated the importance of monoamine systems in the behavioral effects of methamphetamine. Human laboratory procedures of drug-discrimination are well suited to assess neuropharmacological mechanisms of the training drug by studying pharmacological manipulation. In this human laboratory study, six participants with a history of recreational stimulant use learned to discriminate 10 mg oral methamphetamine. After acquiring the discrimination (i.e., ≥80% correct responding on 4 consecutive sessions), the effects of a range of doses of methamphetamine (0, 2.5, 5, 10 and 15 mg), alone and in combination with 0 and 20 mg aripiprazole (a partial agonist at D2 and 5-HT1A receptors), were assessed. Methamphetamine alone functioned as a discriminative stimulus, produced prototypical stimulant-like subject-rated drug effects (e.g., increased ratings of Good Effects, Talkative-Friendly, and Willing to Pay For) and elevated cardiovascular indices. These effects were generally a function of dose. Aripiprazole alone did not occasion methamphetamine-appropriate responding or produce subject-rated effects, but modestly impaired performance. Administration of aripiprazole significantly attenuated the discriminative-stimulus and cardiovascular effects of methamphetamine, as well as some of the subject-rated drug effects. These results indicate that monoamine systems likely play a role in the behavioral effects of methamphetamine in humans. Moreover, given the concordance between past results with d-amphetamine and the present findings, d-amphetamine can likely serve as a model for the pharmacological effects of methamphetamine. PMID:21694622

Responding for sucrose and wheel-running reinforcement: effect of pre-running.

PubMed

Belke, Terry W

2006-01-10

Six male albino Wistar rats were placed in running wheels and exposed to a fixed interval 30-s schedule that produced either a drop of 15% sucrose solution or the opportunity to run for 15s as reinforcing consequences for lever pressing. Each reinforcer type was signaled by a different stimulus. To assess the effect of pre-running, animals were allowed to run for 1h prior to a session of responding for sucrose and running. Results showed that, after pre-running, response rates in the later segments of the 30-s schedule decreased in the presence of a wheel-running stimulus and increased in the presence of a sucrose stimulus. Wheel-running rates were not affected. Analysis of mean post-reinforcement pauses (PRP) broken down by transitions between successive reinforcers revealed that pre-running lengthened pausing in the presence of the stimulus signaling wheel running and shortened pauses in the presence of the stimulus signaling sucrose. No effect was observed on local response rates. Changes in pausing in the presence of stimuli signaling the two reinforcers were consistent with a decrease in the reinforcing efficacy of wheel running and an increase in the reinforcing efficacy of sucrose. Pre-running decreased motivation to respond for running, but increased motivation to work for food.

Incorporating spike-rate adaptation into a rate code in mathematical and biological neurons

PubMed Central

Ralston, Bridget N.; Flagg, Lucas Q.; Faggin, Eric

2016-01-01

For a slowly varying stimulus, the simplest relationship between a neuron's input and output is a rate code, in which the spike rate is a unique function of the stimulus at that instant. In the case of spike-rate adaptation, there is no unique relationship between input and output, because the spike rate at any time depends both on the instantaneous stimulus and on prior spiking (the “history”). To improve the decoding of spike trains produced by neurons that show spike-rate adaptation, we developed a simple scheme that incorporates “history” into a rate code. We utilized this rate-history code successfully to decode spike trains produced by 1) mathematical models of a neuron in which the mechanism for adaptation (IAHP) is specified, and 2) the gastropyloric receptor (GPR2), a stretch-sensitive neuron in the stomatogastric nervous system of the crab Cancer borealis, that exhibits long-lasting adaptation of unknown origin. Moreover, when we modified the spike rate either mathematically in a model system or by applying neuromodulatory agents to the experimental system, we found that changes in the rate-history code could be related to the biophysical mechanisms responsible for altering the spiking. PMID:26888106

Generalization of cross-modal stimulus equivalence classes: operant processes as components in human category formation.

PubMed Central

Lane, S D; Clow, J K; Innis, A; Critchfield, T S

1998-01-01

This study employed a stimulus-class rating procedure to explore whether stimulus equivalence and stimulus generalization can combine to promote the formation of open-ended categories incorporating cross-modal stimuli. A pretest of simple auditory discrimination indicated that subjects (college students) could discriminate among a range of tones used in the main study. Before beginning the main study, 10 subjects learned to use a rating procedure for categorizing sets of stimuli as class consistent or class inconsistent. After completing conditional discrimination training with new stimuli (shapes and tones), the subjects demonstrated the formation of cross-modal equivalence classes. Subsequently, the class-inclusion rating procedure was reinstituted, this time with cross-modal sets of stimuli drawn from the equivalence classes. On some occasions, the tones of the equivalence classes were replaced by novel tones. The probability that these novel sets would be rated as class consistent was generally a function of the auditory distance between the novel tone and the tone that was explicitly included in the equivalence class. These data extend prior work on generalization of equivalence classes, and support the role of operant processes in human category formation. PMID:9821680

An Evaluation of the Number of Presentations of Target Sounds during Stimulus-Stimulus Pairing Trials

ERIC Educational Resources Information Center

Miliotis, Adriane; Sidener, Tina M.; Reeve, Kenneth F.; Carbone, Vincent; Sidener, David W.; Rader, Lisa; Delmolino, Lara

2012-01-01

Stimulus-stimulus pairing (SSP) of vocalizations pairs the speech of others with the delivery of highly preferred items. The goal of this procedure is to produce a temporary increase in vocalizations, thus creating a larger variety of sounds that can subsequently be brought under appropriate stimulus control (Esch, Carr, & Grow, 2009). In this…

Using Single-trial EEG to Predict and Analyze Subsequent Memory

PubMed Central

Noh, Eunho; Herzmann, Grit; Curran, Tim; de Sa, Virginia R.

2013-01-01

We show that it is possible to successfully predict subsequent memory performance based on single-trial EEG activity before and during item presentation in the study phase. Two-class classification was conducted to predict subsequently remembered vs. forgotten trials based on subjects’ responses in the recognition phase. The overall accuracy across 18 subjects was 59.6 % by combining pre- and during-stimulus information. The single-trial classification analysis provides a dimensionality reduction method to project the high-dimensional EEG data onto a discriminative space. These projections revealed novel findings in the pre- and during-stimulus period related to levels of encoding. It was observed that the pre-stimulus information (specifically oscillatory activity between 25–35Hz) −300 to 0 ms before stimulus presentation and during-stimulus alpha (7–12 Hz) information between 1000–1400 ms after stimulus onset distinguished between recollection and familiarity while the during-stimulus alpha information and temporal information between 400–800 ms after stimulus onset mapped these two states to similar values. PMID:24064073

The effect of stimulus strength on the speed and accuracy of a perceptual decision.

PubMed

Palmer, John; Huk, Alexander C; Shadlen, Michael N

2005-05-02

Both the speed and the accuracy of a perceptual judgment depend on the strength of the sensory stimulation. When stimulus strength is high, accuracy is high and response time is fast; when stimulus strength is low, accuracy is low and response time is slow. Although the psychometric function is well established as a tool for analyzing the relationship between accuracy and stimulus strength, the corresponding chronometric function for the relationship between response time and stimulus strength has not received as much consideration. In this article, we describe a theory of perceptual decision making based on a diffusion model. In it, a decision is based on the additive accumulation of sensory evidence over time to a bound. Combined with simple scaling assumptions, the proportional-rate and power-rate diffusion models predict simple analytic expressions for both the chronometric and psychometric functions. In a series of psychophysical experiments, we show that this theory accounts for response time and accuracy as a function of both stimulus strength and speed-accuracy instructions. In particular, the results demonstrate a close coupling between response time and accuracy. The theory is also shown to subsume the predictions of Piéron's Law, a power function dependence of response time on stimulus strength. The theory's analytic chronometric function allows one to extend theories of accuracy to response time.

On the independence of visual awareness and metacognition: a signal detection theoretic analysis.

PubMed

Jachs, Barbara; Blanco, Manuel J; Grantham-Hill, Sarah; Soto, David

2015-04-01

Classically, visual awareness and metacognition are thought to be intimately linked, with our knowledge of the correctness of perceptual choices (henceforth metacognition) being dependent on the level of stimulus awareness. Here we used a signal detection theoretic approach involving a Gabor orientation discrimination task in conjunction with trial-by-trial ratings of perceptual awareness and response confidence in order to gauge estimates of type-1 (perceptual) orientation sensitivity and type-2 (metacognitive) sensitivity at different levels of stimulus awareness. Data from three experiments indicate that while the level of stimulus awareness had a profound impact on type-1 perceptual sensitivity, the awareness effect on type-2 metacognitive sensitivity was far lower by comparison. The present data pose a challenge for signal detection theoretic models in which both type-1 (perceptual) and type-2 (metacognitive) processes are assumed to operate on the same input. More broadly, the findings challenge the commonly held view that metacognition is tightly coupled to conscious states. (c) 2015 APA, all rights reserved.

Effect of stimulus size and luminance on the rod-, cone-, and melanopsin-mediated pupillary light reflex

PubMed Central

Park, Jason C.; McAnany, J. Jason

2015-01-01

This study determined if the pupillary light reflex (PLR) driven by brief stimulus presentations can be accounted for by the product of stimulus luminance and area (i.e., corneal flux density, CFD) under conditions biased toward the rod, cone, and melanopsin pathways. Five visually normal subjects participated in the study. Stimuli consisted of 1-s short- and long-wavelength flashes that spanned a large range of luminance and angular subtense. The stimuli were presented in the central visual field in the dark (rod and melanopsin conditions) and against a rod-suppressing short-wavelength background (cone condition). Rod- and cone-mediated PLRs were measured at the maximum constriction after stimulus onset whereas the melanopsin-mediated PLR was measured 5–7 s after stimulus offset. The rod- and melanopsin-mediated PLRs were well accounted for by CFD, such that doubling the stimulus luminance had the same effect on the PLR as doubling the stimulus area. Melanopsin-mediated PLRs were elicited only by short-wavelength, large (>16°) stimuli with luminance greater than 10 cd/m2, but when present, the melanopsin-mediated PLR was well accounted for by CFD. In contrast, CFD could not account for the cone-mediated PLR because the PLR was approximately independent of stimulus size but strongly dependent on stimulus luminance. These findings highlight important differences in how stimulus luminance and size combine to govern the PLR elicited by brief flashes under rod-, cone-, and melanopsin-mediated conditions. PMID:25788707

Highly Reconfigurable Beamformer Stimulus Generator

NASA Astrophysics Data System (ADS)

Vaviļina, E.; Gaigals, G.

2018-02-01

The present paper proposes a highly reconfigurable beamformer stimulus generator of radar antenna array, which includes three main blocks: settings of antenna array, settings of objects (signal sources) and a beamforming simulator. Following from the configuration of antenna array and object settings, different stimulus can be generated as the input signal for a beamformer. This stimulus generator is developed under a greater concept with two utterly independent paths where one is the stimulus generator and the other is the hardware beamformer. Both paths can be complemented in final and in intermediate steps as well to check and improve system performance. This way the technology development process is promoted by making each of the future hardware steps more substantive. Stimulus generator configuration capabilities and test results are presented proving the application of the stimulus generator for FPGA based beamforming unit development and tuning as an alternative to an actual antenna system.

A novel paradigm to evaluate conditioned pain modulation in fibromyalgia.

PubMed

Schoen, Cynthia J; Ablin, Jacob N; Ichesco, Eric; Bhavsar, Rupal J; Kochlefl, Laura; Harris, Richard E; Clauw, Daniel J; Gracely, Richard H; Harte, Steven E

2016-01-01

Application of noxious stimulation to one body area reduces pain sensitivity in a remote body area through activation of an endogenous pain-inhibitory network, a behavioral phenomenon referred to as conditioned pain modulation (CPM). The efficiency of CPM is predictive of a variety of health outcomes, while impaired CPM has been associated with various chronic pain conditions. Current methods used to assess CPM vary widely, and interest in CPM method development remains strong. Here, we evaluated a novel method for assessing CPM in healthy controls and fibromyalgia (FM) patients using thumb pressure as both a test and conditioning stimulus. Sixteen female FM patients and 14 matched healthy controls underwent CPM testing with thumbnail pressure as the test stimulus, and either cold water or noxious pressure as the conditioning stimulus. CPM magnitude was evaluated as the difference in pain rating of the test stimulus applied before and during the conditioning stimulus. In healthy controls, application of either pressure or cold water conditioning stimulation induced CPM as evidenced by a significant reduction in test stimulus pain rating during conditioning ( P =0.007 and P =0.021, respectively). In contrast, in FM patients, neither conditioning stimulus induced a significant CPM effect ( P >0.274). There was a significant difference in CPM magnitude for FM patients compared to healthy controls with noxious pressure conditioning stimulation ( P =0.023); however, no significant difference in CPM was found between groups using cold water as a conditioning stimulus ( P =0.269). The current study demonstrates that thumbnail pressure can be used as both a test and conditioning stimulus in the assessment of CPM. This study further confirms previous findings of attenuated CPM in FM patients compared with healthy controls.

A novel paradigm to evaluate conditioned pain modulation in fibromyalgia

PubMed Central

Schoen, Cynthia J; Ablin, Jacob N; Ichesco, Eric; Bhavsar, Rupal J; Kochlefl, Laura; Harris, Richard E; Clauw, Daniel J; Gracely, Richard H; Harte, Steven E

2016-01-01

Introduction Application of noxious stimulation to one body area reduces pain sensitivity in a remote body area through activation of an endogenous pain-inhibitory network, a behavioral phenomenon referred to as conditioned pain modulation (CPM). The efficiency of CPM is predictive of a variety of health outcomes, while impaired CPM has been associated with various chronic pain conditions. Current methods used to assess CPM vary widely, and interest in CPM method development remains strong. Here, we evaluated a novel method for assessing CPM in healthy controls and fibromyalgia (FM) patients using thumb pressure as both a test and conditioning stimulus. Methods Sixteen female FM patients and 14 matched healthy controls underwent CPM testing with thumbnail pressure as the test stimulus, and either cold water or noxious pressure as the conditioning stimulus. CPM magnitude was evaluated as the difference in pain rating of the test stimulus applied before and during the conditioning stimulus. Results In healthy controls, application of either pressure or cold water conditioning stimulation induced CPM as evidenced by a significant reduction in test stimulus pain rating during conditioning (P=0.007 and P=0.021, respectively). In contrast, in FM patients, neither conditioning stimulus induced a significant CPM effect (P>0.274). There was a significant difference in CPM magnitude for FM patients compared to healthy controls with noxious pressure conditioning stimulation (P=0.023); however, no significant difference in CPM was found between groups using cold water as a conditioning stimulus (P=0.269). Conclusion The current study demonstrates that thumbnail pressure can be used as both a test and conditioning stimulus in the assessment of CPM. This study further confirms previous findings of attenuated CPM in FM patients compared with healthy controls. PMID:27713648

Coding and decoding with adapting neurons: a population approach to the peri-stimulus time histogram.

PubMed

Naud, Richard; Gerstner, Wulfram

2012-01-01

The response of a neuron to a time-dependent stimulus, as measured in a Peri-Stimulus-Time-Histogram (PSTH), exhibits an intricate temporal structure that reflects potential temporal coding principles. Here we analyze the encoding and decoding of PSTHs for spiking neurons with arbitrary refractoriness and adaptation. As a modeling framework, we use the spike response model, also known as the generalized linear neuron model. Because of refractoriness, the effect of the most recent spike on the spiking probability a few milliseconds later is very strong. The influence of the last spike needs therefore to be described with high precision, while the rest of the neuronal spiking history merely introduces an average self-inhibition or adaptation that depends on the expected number of past spikes but not on the exact spike timings. Based on these insights, we derive a 'quasi-renewal equation' which is shown to yield an excellent description of the firing rate of adapting neurons. We explore the domain of validity of the quasi-renewal equation and compare it with other rate equations for populations of spiking neurons. The problem of decoding the stimulus from the population response (or PSTH) is addressed analogously. We find that for small levels of activity and weak adaptation, a simple accumulator of the past activity is sufficient to decode the original input, but when refractory effects become large decoding becomes a non-linear function of the past activity. The results presented here can be applied to the mean-field analysis of coupled neuron networks, but also to arbitrary point processes with negative self-interaction.

Prior probability and feature predictability interactively bias perceptual decisions

PubMed Central

Dunovan, Kyle E.; Tremel, Joshua J.; Wheeler, Mark E.

2014-01-01

Anticipating a forthcoming sensory experience facilitates perception for expected stimuli but also hinders perception for less likely alternatives. Recent neuroimaging studies suggest that expectation biases arise from feature-level predictions that enhance early sensory representations and facilitate evidence accumulation for contextually probable stimuli while suppressing alternatives. Reasonably then, the extent to which prior knowledge biases subsequent sensory processing should depend on the precision of expectations at the feature level as well as the degree to which expected features match those of an observed stimulus. In the present study we investigated how these two sources of uncertainty modulated pre- and post-stimulus bias mechanisms in the drift-diffusion model during a probabilistic face/house discrimination task. We tested several plausible models of choice bias, concluding that predictive cues led to a bias in both the starting-point and rate of evidence accumulation favoring the more probable stimulus category. We further tested the hypotheses that prior bias in the starting-point was conditional on the feature-level uncertainty of category expectations and that dynamic bias in the drift-rate was modulated by the match between expected and observed stimulus features. Starting-point estimates suggested that subjects formed a constant prior bias in favor of the face category, which exhibits less feature-level variability, that was strengthened or weakened by trial-wise predictive cues. Furthermore, we found that the gain on face/house evidence was increased for stimuli with less ambiguous features and that this relationship was enhanced by valid category expectations. These findings offer new evidence that bridges psychological models of decision-making with recent predictive coding theories of perception. PMID:24978303

The impact of early visual cortex transcranial magnetic stimulation on visual working memory precision and guess rate.

PubMed

Rademaker, Rosanne L; van de Ven, Vincent G; Tong, Frank; Sack, Alexander T

2017-01-01

Neuroimaging studies have demonstrated that activity patterns in early visual areas predict stimulus properties actively maintained in visual working memory. Yet, the mechanisms by which such information is represented remain largely unknown. In this study, observers remembered the orientations of 4 briefly presented gratings, one in each quadrant of the visual field. A 10Hz Transcranial Magnetic Stimulation (TMS) triplet was applied directly at stimulus offset, or midway through a 2-second delay, targeting early visual cortex corresponding retinotopically to a sample item in the lower hemifield. Memory for one of the four gratings was probed at random, and participants reported this orientation via method of adjustment. Recall errors were smaller when the visual field location targeted by TMS overlapped with that of the cued memory item, compared to errors for stimuli probed diagonally to TMS. This implied topographic storage of orientation information, and a memory-enhancing effect at the targeted location. Furthermore, early pulses impaired performance at all four locations, compared to late pulses. Next, response errors were fit empirically using a mixture model to characterize memory precision and guess rates. Memory was more precise for items proximal to the pulse location, irrespective of pulse timing. Guesses were more probable with early TMS pulses, regardless of stimulus location. Thus, while TMS administered at the offset of the stimulus array might disrupt early-phase consolidation in a non-topographic manner, TMS also boosts the precise representation of an item at its targeted retinotopic location, possibly by increasing attentional resources or by injecting a beneficial amount of noise.

The impact of early visual cortex transcranial magnetic stimulation on visual working memory precision and guess rate

PubMed Central

van de Ven, Vincent G.; Tong, Frank; Sack, Alexander T.

2017-01-01

Neuroimaging studies have demonstrated that activity patterns in early visual areas predict stimulus properties actively maintained in visual working memory. Yet, the mechanisms by which such information is represented remain largely unknown. In this study, observers remembered the orientations of 4 briefly presented gratings, one in each quadrant of the visual field. A 10Hz Transcranial Magnetic Stimulation (TMS) triplet was applied directly at stimulus offset, or midway through a 2-second delay, targeting early visual cortex corresponding retinotopically to a sample item in the lower hemifield. Memory for one of the four gratings was probed at random, and participants reported this orientation via method of adjustment. Recall errors were smaller when the visual field location targeted by TMS overlapped with that of the cued memory item, compared to errors for stimuli probed diagonally to TMS. This implied topographic storage of orientation information, and a memory-enhancing effect at the targeted location. Furthermore, early pulses impaired performance at all four locations, compared to late pulses. Next, response errors were fit empirically using a mixture model to characterize memory precision and guess rates. Memory was more precise for items proximal to the pulse location, irrespective of pulse timing. Guesses were more probable with early TMS pulses, regardless of stimulus location. Thus, while TMS administered at the offset of the stimulus array might disrupt early-phase consolidation in a non-topographic manner, TMS also boosts the precise representation of an item at its targeted retinotopic location, possibly by increasing attentional resources or by injecting a beneficial amount of noise. PMID:28384347

Effects of inferior olive lesion on fear-conditioned bradycardia

PubMed Central

Kotajima, Hiroko; Sakai, Kazuhisa; Hashikawa, Tsutomu

2014-01-01

The inferior olive (IO) sends excitatory inputs to the cerebellar cortex and cerebellar nuclei through the climbing fibers. In eyeblink conditioning, a model of motor learning, the inactivation of or a lesion in the IO impairs the acquisition or expression of conditioned eyeblink responses. Additionally, climbing fibers originating from the IO are believed to transmit the unconditioned stimulus to the cerebellum in eyeblink conditioning. Studies using fear-conditioned bradycardia showed that the cerebellum is associated with adaptive control of heart rate. However, the role of inputs from the IO to the cerebellum in fear-conditioned bradycardia has not yet been investigated. To examine this possible role, we tested fear-conditioned bradycardia in mice by selective disruption of the IO using 3-acetylpyridine. In a rotarod test, mice with an IO lesion were unable to remain on the rod. The number of neurons of IO nuclei in these mice was decreased to ∼40% compared with control mice. Mice with an IO lesion did not show changes in the mean heart rate or in heart rate responses to a conditioned stimulus, or in their responses to a painful stimulus in a tail-flick test. However, they did show impairment of the acquisition/expression of conditioned bradycardia and attenuation of heart rate responses to a pain stimulus used as an unconditioned stimulus. These results indicate that the IO inputs to the cerebellum play a key role in the acquisition/expression of conditioned bradycardia. PMID:24784584

Measuring target detection performance in paradigms with high event rates.

PubMed

Bendixen, Alexandra; Andersen, Søren K

2013-05-01

Combining behavioral and neurophysiological measurements inevitably implies mutual constraints, such as when the neurophysiological measurement requires fast-paced stimulus presentation and hence the attribution of a behavioral response to a particular preceding stimulus becomes ambiguous. We develop and test a method for validly assessing behavioral detection performance in spite of this ambiguity. We examine four approaches taken in the literature to treat such situations. We analytically derive a new variant of computing the classical parameters of signal detection theory, hit and false alarm rates, adapted to fast-paced paradigms. Each of the previous approaches shows specific shortcomings (susceptibility towards response window choice, biased estimates of behavioral detection performance). Superior performance of our new approach is demonstrated for both simulated and empirical behavioral data. Further evidence is provided by reliable correspondence between behavioral performance and the N2b component as an electrophysiological indicator of target detection. The appropriateness of our approach is substantiated by both theoretical and empirical arguments. We demonstrate an easy-to-implement solution for measuring target detection performance independent of the rate of event presentation. Thus overcoming the measurement bias of previous approaches, our method will help to clarify the behavioral relevance of different measures of cortical activation. Copyright © 2012 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Stimulus appraisal modulates cardiac reactivity to briefly presented mutilation pictures.

PubMed

Mocaiber, Izabela; Perakakis, Pandelis; Pereira, Mirtes Garcia; Pinheiro, Walter Machado; Volchan, Eliane; de Oliveira, Letícia; Vila, Jaime

2011-09-01

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). Copyright © 2011 Elsevier B.V. All rights reserved.

The autoshaping procedure as a residual block clock

PubMed Central

Dinsmoor, James A.; Dougan, James D.; Pfister, John; Thiels, Edda

1992-01-01

In the first experiment, 4 pigeons were each presented with a recurring sequence of four key colors followed by the delivery of grain (block clock). Once the rate of pecking had stabilized, three of the colors were replaced, during different series of sessions, by a darkening of the key. The rate of pecking was reduced within those segments of the interval between deliveries of food during which the key was dark; when the key was dark during the final portion of the interval, rates were reduced throughout the entire interval. In the second experiment, 3 new pigeons were exposed to a different sequence of colors, and the final stimulus was replaced in successive conditions by a novel color, a darkened key, and a restoration of the original color. The data indicated that darkening the key had a more severe, more extensive, and more persistent effect than did a mere change in color. These results suggest that it may be fruitful to conceptualize the autoshaping procedure as a special version of the block clock in which pecking is suppressed throughout the greater part of the interval by darkening the key. In the final condition, the same stimulus appeared in each of the last three portions of the interval. The rate of pecking was lower during the last two portions than when distinctive colors were presented, with the peak rate now appearing in the fifth of seven equal temporal components. PMID:16812666

Does erotic stimulus presentation design affect brain activation patterns? Event-related vs. blocked fMRI designs.

PubMed

Bühler, Mira; Vollstädt-Klein, Sabine; Klemen, Jane; Smolka, Michael N

2008-07-22

Existing brain imaging studies, investigating sexual arousal via the presentation of erotic pictures or film excerpts, have mainly used blocked designs with long stimulus presentation times. To clarify how experimental functional magnetic resonance imaging (fMRI) design affects stimulus-induced brain activity, we compared brief event-related presentation of erotic vs. neutral stimuli with blocked presentation in 10 male volunteers. Brain activation differed depending on design type in only 10% of the voxels showing task related brain activity. Differences between blocked and event-related stimulus presentation were found in occipitotemporal and temporal regions (Brodmann Area (BA) 19, 37, 48), parietal areas (BA 7, 40) and areas in the frontal lobe (BA 6, 44). Our results suggest that event-related designs might be a potential alternative when the core interest is the detection of networks associated with immediate processing of erotic stimuli.Additionally, blocked, compared to event-related, stimulus presentation allows the emergence and detection of non-specific secondary processes, such as sustained attention, motor imagery and inhibition of sexual arousal.

Does erotic stimulus presentation design affect brain activation patterns? Event-related vs. blocked fMRI designs

PubMed Central

Bühler, Mira; Vollstädt-Klein, Sabine; Klemen, Jane; Smolka, Michael N

2008-01-01

Background Existing brain imaging studies, investigating sexual arousal via the presentation of erotic pictures or film excerpts, have mainly used blocked designs with long stimulus presentation times. Methods To clarify how experimental functional magnetic resonance imaging (fMRI) design affects stimulus-induced brain activity, we compared brief event-related presentation of erotic vs. neutral stimuli with blocked presentation in 10 male volunteers. Results Brain activation differed depending on design type in only 10% of the voxels showing task related brain activity. Differences between blocked and event-related stimulus presentation were found in occipitotemporal and temporal regions (Brodmann Area (BA) 19, 37, 48), parietal areas (BA 7, 40) and areas in the frontal lobe (BA 6, 44). Conclusion Our results suggest that event-related designs might be a potential alternative when the core interest is the detection of networks associated with immediate processing of erotic stimuli. Additionally, blocked, compared to event-related, stimulus presentation allows the emergence and detection of non-specific secondary processes, such as sustained attention, motor imagery and inhibition of sexual arousal. PMID:18647397

Statistical context shapes stimulus-specific adaptation in human auditory cortex.

PubMed

Herrmann, Björn; Henry, Molly J; Fromboluti, Elisa Kim; McAuley, J Devin; Obleser, Jonas

2015-04-01

Stimulus-specific adaptation is the phenomenon whereby neural response magnitude decreases with repeated stimulation. Inconsistencies between recent nonhuman animal recordings and computational modeling suggest dynamic influences on stimulus-specific adaptation. The present human electroencephalography (EEG) study investigates the potential role of statistical context in dynamically modulating stimulus-specific adaptation by examining the auditory cortex-generated N1 and P2 components. As in previous studies of stimulus-specific adaptation, listeners were presented with oddball sequences in which the presentation of a repeated tone was infrequently interrupted by rare spectral changes taking on three different magnitudes. Critically, the statistical context varied with respect to the probability of small versus large spectral changes within oddball sequences (half of the time a small change was most probable; in the other half a large change was most probable). We observed larger N1 and P2 amplitudes (i.e., release from adaptation) for all spectral changes in the small-change compared with the large-change statistical context. The increase in response magnitude also held for responses to tones presented with high probability, indicating that statistical adaptation can overrule stimulus probability per se in its influence on neural responses. Computational modeling showed that the degree of coadaptation in auditory cortex changed depending on the statistical context, which in turn affected stimulus-specific adaptation. Thus the present data demonstrate that stimulus-specific adaptation in human auditory cortex critically depends on statistical context. Finally, the present results challenge the implicit assumption of stationarity of neural response magnitudes that governs the practice of isolating established deviant-detection responses such as the mismatch negativity. Copyright © 2015 the American Physiological Society.

Analyzing Stimulus-Stimulus Pairing Effects on Preferences for Speech Sounds

ERIC Educational Resources Information Center

Petursdottir, Anna Ingeborg; Carp, Charlotte L.; Matthies, Derek W.; Esch, Barbara E.

2011-01-01

Several studies have demonstrated effects of stimulus-stimulus pairing (SSP) on children's vocalizations, but numerous treatment failures have also been reported. The present study attempted to isolate procedural variables related to failures of SSP to condition speech sounds as reinforcers. Three boys diagnosed with autism-spectrum disorders…

New efficient stimuli for evoking frequency-specific auditory steady-state responses.

PubMed

Stürzebecher, Ekkehard; Cebulla, Mario; Elberling, Claus; Berger, Thomas

2006-06-01

ASSR is a promising tool for the objective frequency-specific assessment of hearing thresholds in children. The stimulus generally used for ASSR recording (single amplitude-modulated carrier) only activates a small area on the basilar membrane. Therefore, the response amplitude is low. A stimulus with a broader frequency spectrum can be composed by adding several cosines whose frequency intervals comply with the desired stimulus repetition rate. Compensation of the travelling wave delay on the basilar membrane is possible with a stimulus of this type. Through this, a better synchronization of the neural response can be obtained and, as a result, higher response amplitudes can be expected, particularly for low-frequency stimuli. The additional introduction of a frequency offset enables the use of a q-sample test for the response detection, especially important at 500 Hz. The results of investigations carried out on a large group of normally hearing test subjects have confirmed the efficiency of this stimulus design. The new stimuli lead to significantly improved ASSRs with higher SNRs and thus higher detection rates and shorter detection times.

Response properties of ON-OFF retinal ganglion cells to high-order stimulus statistics.

PubMed

Xiao, Lei; Gong, Han-Yan; Gong, Hai-Qing; Liang, Pei-Ji; Zhang, Pu-Ming

2014-10-17

The visual stimulus statistics are the fundamental parameters to provide the reference for studying visual coding rules. In this study, the multi-electrode extracellular recording experiments were designed and implemented on bullfrog retinal ganglion cells to explore the neural response properties to the changes in stimulus statistics. The changes in low-order stimulus statistics, such as intensity and contrast, were clearly reflected in the neuronal firing rate. However, it was difficult to distinguish the changes in high-order statistics, such as skewness and kurtosis, only based on the neuronal firing rate. The neuronal temporal filtering and sensitivity characteristics were further analyzed. We observed that the peak-to-peak amplitude of the temporal filter and the neuronal sensitivity, which were obtained from either neuronal ON spikes or OFF spikes, could exhibit significant changes when the high-order stimulus statistics were changed. These results indicate that in the retina, the neuronal response properties may be reliable and powerful in carrying some complex and subtle visual information. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

An adaptive supramolecular hydrogel comprising self-sorting double nanofibre networks

NASA Astrophysics Data System (ADS)

Shigemitsu, Hajime; Fujisaku, Takahiro; Tanaka, Wataru; Kubota, Ryou; Minami, Saori; Urayama, Kenji; Hamachi, Itaru

2018-02-01

Novel soft materials should comprise multiple supramolecular nanostructures whose responses (for example, assembly and disassembly) to external stimuli can be controlled independently. Such multicomponent systems are present in living cells and control the formation and break-up of a variety of supramolecular assemblies made of proteins, lipids, DNA and RNA in response to external stimuli; however, artificial counterparts are challenging to make. Here, we present a hybrid hydrogel consisting of a self-sorting double network of nanofibres in which each network responds to an applied external stimulus independent of the other. The hydrogel can be made to change its mechanical properties and rates of release of encapsulated proteins by adding Na2S2O4 or bacterial alkaline phosphatase. Notably, the properties of the gel depend on the order in which the external stimuli are applied. Multicomponent hydrogels comprising orthogonal stimulus-responsive supramolecular assemblies would be suitable for designing novel adaptive materials.

Lateral orbitofrontal cortex anticipates choices and integrates prior with current information

PubMed Central

Nogueira, Ramon; Abolafia, Juan M.; Drugowitsch, Jan; Balaguer-Ballester, Emili; Sanchez-Vives, Maria V.; Moreno-Bote, Rubén

2017-01-01

Adaptive behavior requires integrating prior with current information to anticipate upcoming events. Brain structures related to this computation should bring relevant signals from the recent past into the present. Here we report that rats can integrate the most recent prior information with sensory information, thereby improving behavior on a perceptual decision-making task with outcome-dependent past trial history. We find that anticipatory signals in the orbitofrontal cortex about upcoming choice increase over time and are even present before stimulus onset. These neuronal signals also represent the stimulus and relevant second-order combinations of past state variables. The encoding of choice, stimulus and second-order past state variables resides, up to movement onset, in overlapping populations. The neuronal representation of choice before stimulus onset and its build-up once the stimulus is presented suggest that orbitofrontal cortex plays a role in transforming immediate prior and stimulus information into choices using a compact state-space representation. PMID:28337990

Response rate and reinforcement rate in Pavlovian conditioning.

PubMed

Harris, Justin A; Carpenter, Joanne S

2011-10-01

Four experiments used delay conditioning of magazine approach in rats to investigate the relationship between the rate of responding, R, to a conditioned stimulus (CS) and the rate, r, at which the CS is reinforced with the unconditioned stimulus (US). Rats were concurrently trained with four variable-duration CSs with different rs, either as a result of differences in the mean CS-US interval or in the proportion of CS presentations that ended with the US. In each case, R was systematically related to r, and the relationship was very accurately characterized by a hyperbolic function, R = Ar/(r +c). Accordingly, the reciprocal of these two variables-response interval, I (= 1/R), and CS-US interval, i (= 1/r) - were related by a simple affine (straight line) transformation, I = mi+b. This latter relationship shows that each increment in the time that the rats had to wait for food produced a linear increment in the time they waited between magazine entries. We discuss the close agreement between our findings and the Matching Law (Herrnstein, 1970) and consider their implications for both associative theories (e.g., Rescorla & Wagner, 1972) and nonassociative theories (Gallistel & Gibbon, 2000) of conditioning. (PsycINFO Database Record (c) 2011 APA, all rights reserved).

Disrupting reconsolidation of fear memory in humans by a noradrenergic β-blocker.

PubMed

Kindt, Merel; Soeter, Marieke; Sevenster, Dieuwke

2014-12-18

The basic design used in our human fear-conditioning studies on disrupting reconsolidation includes testing over different phases across three consecutive days. On day 1 - the fear acquisition phase, healthy participants are exposed to a series of picture presentations. One picture stimulus (CS1+) is repeatedly paired with an aversive electric stimulus (US), resulting in the acquisition of a fear association, whereas another picture stimulus (CS2-) is never followed by an US. On day 2 - the memory reactivation phase, the participants are re-exposed to the conditioned stimulus without the US (CS1-), which typically triggers a conditioned fear response. After the memory reactivation we administer an oral dose of 40 mg of propranolol HCl, a β-adrenergic receptor antagonist that indirectly targets the protein synthesis required for reconsolidation by inhibiting the noradrenaline-stimulated CREB phosphorylation. On day 3 - the test phase, the participants are again exposed to the unreinforced conditioned stimuli (CS1- and CS2-) in order to measure the fear-reducing effect of the manipulation. This retention test is followed by an extinction procedure and the presentation of situational triggers to test for the return of fear. Potentiation of the eye blink startle reflex is measured as an index for conditioned fear responding. Declarative knowledge of the fear association is measured through online US expectancy ratings during each CS presentation. In contrast to extinction learning, disrupting reconsolidation targets the original fear memory thereby preventing the return of fear. Although the clinical applications are still in their infancy, disrupting reconsolidation of fear memory seems to be a promising new technique with the prospect to persistently dampen the expression of fear memory in patients suffering from anxiety disorders and other psychiatric disorders.

Transfer of classical eyeblink conditioning with electrical stimulation of mPFC or tone as conditioned stimulus in guinea pigs.

PubMed

Yao, Juan; Wu, Guang-Yan; Liu, Guo-Long; Liu, Shu-Lei; Yang, Yi; Wu, Bing; Li, Xuan; Feng, Hua; Sui, Jian-Feng

2014-11-01

Learning with a stimulus from one sensory modality can facilitate subsequent learning with a new stimulus from a different sensory modality. To date, the characteristics and mechanism of this phenomenon named transfer effect still remain ambiguous. Our previous work showed that electrical stimulation of medial prefrontal cortex (mPFC) as a conditioned stimulus (CS) could successfully establish classical eyeblink conditioning (EBC). The present study aimed to (1) observe whether transfer of EBC learning would occur when CSs shift between central (mPFC electrical stimulation as a CS, mPFC-CS) and peripheral (tone as a CS, tone CS); (2) compare the difference in transfer effect between the two paradigms, delay EBC (DEBC) and trace EBC (TEBC). A total of 8 groups of guinea pigs were tested in the study, including 4 experimental groups and 4 control groups. Firstly, the experimental groups accepted central (or peripheral) CS paired with corneal airpuff unconditioned stimulus (US); then, CS shifted to the peripheral (or central) and paired with US. The control groups accepted corresponding central (or peripheral) CS and pseudo-paired with US, and then shifted CS from central (or peripheral) to peripheral (or central) and paired with US. The results showed that the acquisition rates of EBC were higher in experimental groups than in control groups after CS switching from central to peripheral or vice versa, and the CR acquisition rate was remarkably higher in DEBC than in TEBC in both transfer ways. The results indicate that EBC transfer can occur between learning established with mPFC-CS and tone CS. Memory of CS-US association for delay paradigm was less disturbed by the sudden switch of CS than for trace paradigm. This study provides new insight into neural mechanisms underlying conditioned reflex as well as the role of mPFC. Copyright © 2014 Elsevier B.V. All rights reserved.

Mitigating passive fatigue during monotonous drives with thermal stimuli: Insights into the effect of different stimulation durations.

PubMed

Schmidt, Elisabeth; Bullinger, Angelika C

2017-12-12

Driving on monotonous roads has been shown to cause passive fatigue as even non-sleep-deprived drivers suffer from the lack of stimuli. Consequently, alertness is reduced and the risk of accidents increases. To counteract this risk, measures need to be taken to mitigate driver fatigue. While in the past, some studies have been focused on the potential of thermal stimuli to reduce fatigue, their results seem inconclusive. Examining the study conditions in which the thermal stimuli were studied, it becomes obvious that the duration of the thermal stimulus strongly affects perceived fatigue. To better understand this relation, a driving simulator study (n=33) was conducted investigating both a 2min and a 4min thermal stimulus (15öC), where air was circulated on non-sleep-deprived drivers. For the 4min stimulus, patterns of increased sympathetic activity (i.e. significant pupil dilatation and bradycardia) were recorded. Furthermore, participants subjectively rated fatigue significantly lower when the stimuli were applied, and preferred driving with the stimulus. The superior performance of the 4min stimulus can be derived from a longer effect on the physiological data as well as even lower subjective fatigue ratings. Results also point to the limits of thermal stimulation: 6min after the stimuli, the participants no longer feel an effect (based on subjective ratings). Future research on passive fatigue countermeasures should hence build on the identified effect of a 4min cooling stimulus to increase physiological arousal and focus on the opportunities to increase effect duration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Visual awareness suppression by pre-stimulus brain stimulation; a neural effect.

PubMed

Jacobs, Christianne; Goebel, Rainer; Sack, Alexander T

2012-01-02

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. Copyright © 2011 Elsevier Inc. All rights reserved.

Supertaster, super reactive: oral sensitivity for bitter taste modulates emotional approach and avoidance behavior in the affective startle paradigm.

PubMed

Herbert, Cornelia; Platte, Petra; Wiemer, Julian; Macht, Michael; Blumenthal, Terry D

2014-08-01

People differ in both their sensitivity for bitter taste and their tendency to respond to emotional stimuli with approach or avoidance. The present study investigated the relationship between these sensitivities in an affective picture paradigm with startle responding. Emotion-induced changes in arousal and attention (pupil modulation), priming of approach and avoidance behavior (startle reflex modulation), and subjective evaluations (ratings) were examined. Sensitivity for bitter taste was assessed with the 6-n-propylthiouracil (PROP)-sensitivity test, which discriminated individuals who were highly sensitive to PROP compared to NaCl (PROP-tasters) and those who were less sensitive or insensitive to the bitter taste of PROP. Neither pupil responses nor picture ratings differed between the two taster groups. The startle eye blink response, however, significantly differentiated PROP-tasters from PROP-insensitive subjects. Facilitated response priming to emotional stimuli emerged in PROP-tasters but not in PROP-insensitive subjects at shorter startle lead intervals (200-300ms between picture onset and startle stimulus onset). At longer lead intervals (3-4.5s between picture onset and startle stimulus onset) affective startle modulation did not differ between the two taster groups. This implies that in PROP-sensitive individuals action tendencies of approach or avoidance are primed immediately after emotional stimulus exposure. These results suggest a link between PROP taste perception and biologically relevant patterns of emotional responding. Direct perception-action links have been proposed to underlie motivational priming effects of the startle reflex, and the present results extend these to the sensory dimension of taste. Copyright © 2014 Elsevier Inc. All rights reserved.

Evaluative Conditioning in Humans: A Meta-Analysis

ERIC Educational Resources Information Center

Hofmann, Wilhelm; De Houwer, Jan; Perugini, Marco; Baeyens, Frank; Crombez, Geert

2010-01-01

This article presents a meta-analysis of research on "evaluative conditioning" (EC), defined as a change in the liking of a stimulus (conditioned stimulus; CS) that results from pairing that stimulus with other positive or negative stimuli (unconditioned stimulus; US). Across a total of 214 studies included in the main sample, the mean…

Stimulus change as a factor in response maintenance with free food available.

PubMed Central

Osborne, S R; Shelby, M

1975-01-01

Rats bar pressed for food on a reinforcement schedule in which every response was reinforced, even though a dish of pellets was present. Initially, auditory and visual stimuli accompanied response-produced food presentation. With stimulus feedback as an added consequence of bar pressing, responding was maintained in the presence of free food; without stimulus feedback, responding decreased to a low level. Auditory feedback maintained slightly more responding than did visual feedback, and both together maintained more responding than did either separately. Almost no responding occurred when the only consequence of bar pressing was stimulus feedback. The data indicated conditioned and sensory reinforcement effects of response-produced stimulus feedback. PMID:1202121

Resting state glutamate predicts elevated pre-stimulus alpha during self-relatedness: A combined EEG-MRS study on "rest-self overlap".

PubMed

Bai, Yu; Nakao, Takashi; Xu, Jiameng; Qin, Pengmin; Chaves, Pedro; Heinzel, Alexander; Duncan, Niall; Lane, Timothy; Yen, Nai-Shing; Tsai, Shang-Yueh; Northoff, Georg

2016-01-01

Recent studies have demonstrated neural overlap between resting state activity and self-referential processing. This "rest-self" overlap occurs especially in anterior cortical midline structures like the perigenual anterior cingulate cortex (PACC). However, the exact neurotemporal and biochemical mechanisms remain to be identified. Therefore, we conducted a combined electroencephalography (EEG)-magnetic resonance spectroscopy (MRS) study. EEG focused on pre-stimulus (e.g., prior to stimulus presentation or perception) power changes to assess the degree to which those changes can predict subjects' perception (and judgment) of subsequent stimuli as high or low self-related. MRS measured resting state concentration of glutamate, focusing on PACC. High pre-stimulus (e.g., prior to stimulus presentation or perception) alpha power significantly correlated with both perception of stimuli judged to be highly self-related and with resting state glutamate concentrations in the PACC. In sum, our results show (i) pre-stimulus (e.g., prior to stimulus presentation or perception) alpha power and resting state glutamate concentration to mediate rest-self overlap that (ii) dispose or incline subjects to assign high degrees of self-relatedness to perceptual stimuli.

Dissociation of binding and learning processes.

PubMed

Moeller, Birte; Frings, Christian

2017-11-01

A single encounter of a stimulus together with a response can result in a short-lived association between the stimulus and the response [sometimes called an event file, see Hommel, Müsseler, Aschersleben, & Prinz, (2001) Behavioral and Brain Sciences, 24, 910-926]. The repetition of stimulus-response pairings typically results in longer lasting learning effects indicating stimulus-response associations (e.g., Logan & Etherton, (1994) Journal of Experimental Psychology: Learning, Memory, and Cognition, 20, 1022-1050]. An important question is whether or not what has been described as stimulus-response binding in action control research is actually identical with an early stage of incidental learning (e.g., binding might be seen as single-trial learning). Here, we present evidence that short-lived binding effects can be distinguished from learning of longer lasting stimulus-response associations. In two experiments, participants always responded to centrally presented target letters that were flanked by response irrelevant distractor letters. Experiment 1 varied whether distractors flanked targets on the horizontal or vertical axis. Binding effects were larger for a horizontal than for a vertical distractor-target configuration, while stimulus configuration did not influence incidental learning of longer lasting stimulus-response associations. In Experiment 2, the duration of the interval between response n - 1 and presentation of display n (500 ms vs. 2000 ms) had opposing influences on binding and learning effects. Both experiments indicate that modulating factors influence stimulus-response binding and incidental learning effects in different ways. We conclude that distinct underlying processes should be assumed for binding and incidental learning effects.

Unconscious classical conditioning of sexual arousal: evidence for the conditioning of female genital arousal to subliminally presented sexual stimuli.

PubMed

Both, Stephanie; Spiering, Mark; Laan, Ellen; Belcome, Sarah; van den Heuvel, Birre; Everaerd, Walter

2008-01-01

Although the assumption that sexual behavior is at least partly learned is common across theories of sexual behavior, classical conditioning of sexual response in women has been seldom studied. The study of unconscious classical conditioning of appetitive sexual responses in women. Vaginal pulse amplitude assessed by vaginal photoplethysmography, and ratings of sexual affective value. Pavlovian conditioning was examined in 18 sexually functional women by using two erotic pictures as conditional stimuli (CSs) and genital vibrotactile stimulation as unconditional stimulus (US). During the acquisition phase, the CSs were presented briefly (30 ms) and were masked by an immediately following masking stimulus. Only one CS (the CS+) was followed by the US during the acquisition phase. Conditioned responses were assessed during the extinction phase with supraliminal presentations of the CS+ and the CS-. Vaginal pulse amplitude was higher in response to the CS+ than during the CS- during the first extinction trial. There was no conditioning effect on ratings of affective value. The experiment demonstrates evidence for unconscious conditioning of genital responses in women, but no evidence for evaluative conditioning. The results add to the limited evidence for classical conditioning of sexual arousal in women, and to increasing evidence for associative emotional learning without awareness.

Distributed Fading Memory for Stimulus Properties in the Primary Visual Cortex

PubMed Central

Singer, Wolf; Maass, Wolfgang

2009-01-01

It is currently not known how distributed neuronal responses in early visual areas carry stimulus-related information. We made multielectrode recordings from cat primary visual cortex and applied methods from machine learning in order to analyze the temporal evolution of stimulus-related information in the spiking activity of large ensembles of around 100 neurons. We used sequences of up to three different visual stimuli (letters of the alphabet) presented for 100 ms and with intervals of 100 ms or larger. Most of the information about visual stimuli extractable by sophisticated methods of machine learning, i.e., support vector machines with nonlinear kernel functions, was also extractable by simple linear classification such as can be achieved by individual neurons. New stimuli did not erase information about previous stimuli. The responses to the most recent stimulus contained about equal amounts of information about both this and the preceding stimulus. This information was encoded both in the discharge rates (response amplitudes) of the ensemble of neurons and, when using short time constants for integration (e.g., 20 ms), in the precise timing of individual spikes (≤∼20 ms), and persisted for several 100 ms beyond the offset of stimuli. The results indicate that the network from which we recorded is endowed with fading memory and is capable of performing online computations utilizing information about temporally sequential stimuli. This result challenges models assuming frame-by-frame analyses of sequential inputs. PMID:20027205

Effect of stimulus intensity on spike-LFP relationship in Secondary Somatosensory cortex

PubMed Central

Hsiao, Steven S.; Crone, Nathan E.; Franaszczuk, Piotr J.; Niebur, Ernst

2008-01-01

Neuronal oscillations in the gamma frequency range have been reported in many cortical areas, but the role they play in cortical processing remains unclear. We tested a recently proposed hypothesis that the intensity of sensory input is coded in the timing of action potentials relative to the phase of gamma oscillations, thus converting amplitude information to a temporal code. We recorded spikes and local field potential (LFP) from secondary somatosensory (SII) cortex in awake monkeys while presenting a vibratory stimulus at different amplitudes. We developed a novel technique based on matching pursuit to study the interaction between the highly transient gamma oscillations and spikes with high time-frequency resolution. We found that spikes were weakly coupled to LFP oscillations in the gamma frequency range (40−80 Hz), and strongly coupled to oscillations in higher gamma frequencies. However, the phase relationship of neither low-gamma nor high-gamma oscillations changed with stimulus intensity, even with a ten-fold increase. We conclude that, in SII, gamma oscillations are synchronized with spikes, but their phase does not vary with stimulus intensity. Furthermore, high-gamma oscillations (>60 Hz) appear to be closely linked to the occurrence of action potentials, suggesting that LFP high-gamma power could be a sensitive index of the population firing rate near the microelectrode. PMID:18632937

A systematic approach to selecting task relevant neurons.

PubMed

Kahn, Kevin; Saxena, Shreya; Eskandar, Emad; Thakor, Nitish; Schieber, Marc; Gale, John T; Averbeck, Bruno; Eden, Uri; Sarma, Sridevi V

2015-04-30

Since task related neurons cannot be specifically targeted during surgery, a critical decision to make is to select which neurons are task-related when performing data analysis. Including neurons unrelated to the task degrade decoding accuracy and confound neurophysiological results. Traditionally, task-related neurons are selected as those with significant changes in firing rate when a stimulus is applied. However, this assumes that neurons' encoding of stimuli are dominated by their firing rate with little regard to temporal dynamics. This paper proposes a systematic approach for neuron selection, which uses a likelihood ratio test to capture the contribution of stimulus to spiking activity while taking into account task-irrelevant intrinsic dynamics that affect firing rates. This approach is denoted as the model deterioration excluding stimulus (MDES) test. MDES is compared to firing rate selection in four case studies: a simulation, a decoding example, and two neurophysiology examples. The MDES rankings in the simulation match closely with ideal rankings, while firing rate rankings are skewed by task-irrelevant parameters. For decoding, 95% accuracy is achieved using the top 8 MDES-ranked neurons, while the top 12 firing-rate ranked neurons are needed. In the neurophysiological examples, MDES matches published results when firing rates do encode salient stimulus information, and uncovers oscillatory modulations in task-related neurons that are not captured when neurons are selected using firing rates. These case studies illustrate the importance of accounting for intrinsic dynamics when selecting task-related neurons and following the MDES approach accomplishes that. MDES selects neurons that encode task-related information irrespective of these intrinsic dynamics which can bias firing rate based selection. Copyright © 2015 Elsevier B.V. All rights reserved.

Conditioned Taste Aversion Is Enhanced When the Unconditioned Stimulus Is Presented in a Different Context

ERIC Educational Resources Information Center

Ishii, Kiyoshi; Iguchi, Yoshio; Fukumoto, Kazuya; Nakayasu, Tomohiro

2008-01-01

Using a conditioned taste aversion procedure with rats as the subjects, two experiments examined the effect of presenting a conditioned stimulus (CS saccharin solution) in one context followed by an unconditioned stimulus (US LiCl) in a different context. Experiment 1 showed that animals which received the above-mentioned procedure (Group D)…

Evaluative conditioning increases with temporal contiguity. The influence of stimulus order and stimulus interval on evaluative conditioning.

PubMed

Gast, Anne; Langer, Sebastian; Sengewald, Marie-Ann

2016-10-01

Evaluative conditioning (EC) is a change in valence that is due to pairing a conditioned stimulus (CS) with another, typically valent, unconditioned stimulus (US). This paper investigates how basic presentation parameters moderate EC effects. In two studies we tested the effectiveness of different temporal relations of the CS and the US, that is, the order in which the stimuli were presented and the temporal distance between them. Both studies showed that the size of EC effects was independent of the presentation order of CS and US within a stimulus pair. Contrary to classical conditioning effects, EC effects are thus not most pronounced after CS-first presentations. Furthermore, as shown in Experiment 2, EC effects increased in magnitude as the temporal interval between CS and US presentations decreased. Experiment 1 showed largest EC effects in the condition with simultaneous presentations - which can be seen as the condition with the temporally closest presentation. In this Experiment stimuli were presented in two different modalities, which might have facilitated simultaneous processing. In Experiment 2, in which all stimuli were presented visually, this advantage of simultaneous presentation was not found. We discuss practical and theoretical implications of our findings. Copyright © 2016 Elsevier B.V. All rights reserved.

BEHAVIORAL MOMENTUM AND ACCUMULATION OF MASS IN MULTIPLE SCHEDULES

PubMed Central

Craig, Andrew R.; Cunningham, Paul J.; Shahan, Timothy A.

2015-01-01

Behavioral momentum theory suggests that the relation between a discriminative-stimulus situation and reinforcers obtained in that context (i.e., the Pavlovian stimulus–reinforcer relation) governs persistence of operant behavior. Within the theory, a mass-like aspect of behavior has been shown to be a power function of predisruption reinforcement rates. Previous investigations of resistance to change in multiple schedules, however, have been restricted to examining response persistence following protracted periods of stability in reinforcer rates within a discriminative situation. Thus, it is unclear how long a stimulus–reinforcer relation must be in effect prior to disruption in order to affect resistance to change. The present experiment examined resistance to change of pigeon’s key pecking following baseline conditions where reinforcer rates that were correlated with discriminative-stimulus situations changed. Across conditions, one multiple-schedule component arranged either relatively higher rates or lower rates of variable-interval food delivery, while the other component arranged the opposite rate. These schedules alternated between multiple-schedule components across blocks of sessions such that reinforcer rates in the components were held constant for 20, 5, 3, 2, or 1 session(s) between alternations. Resistance to extinction was higher in the component that most recently was associated with higher rates of food delivery in all conditions except when schedules alternated daily or every other day. These data suggest that resistance to change in multiple schedules is related to recently experienced reinforcer rates but only when multiple-schedule components are associated with specific reinforcer rates for several sessions. PMID:25787824

Sound envelope encoding in the auditory cortex revealed by neuromagnetic responses in the theta to gamma frequency bands.

PubMed

Miyazaki, Takahiro; Thompson, Jessica; Fujioka, Takako; Ross, Bernhard

2013-04-19

Amplitude fluctuations of natural sounds carry multiple types of information represented at different time scales, such as syllables and voice pitch in speech. However, it is not well understood how such amplitude fluctuations at different time scales are processed in the brain. In the present study we investigated the effect of the stimulus rate on the cortical evoked responses using magnetoencephalography (MEG). We used a two-tone complex sound, whose envelope fluctuated at the difference frequency and induced an acoustic beat sensation. When the beat rate was continuously swept between 3Hz and 60Hz, auditory evoked response showed distinct transient waves at slow rates, while at fast rates continuous sinusoidal oscillations similar to the auditory steady-state response (ASSR) were observed. We further derived temporal modulation transfer functions (TMTF) from amplitudes of the transient responses and from the ASSR. The results identified two critical rates of 12.5Hz and 25Hz, at which consecutive transient responses overlapped with each other. These stimulus rates roughly corresponded to the rates at which the perceptual quality of the sound envelope is known to change. Low rates (> 10Hz) are perceived as loudness fluctuation, medium rates as acoustical flutter, and rates above 25Hz as roughness. We conclude that these results reflect cortical processes that integrate successive acoustic events at different time scales for extracting complex features of natural sound. Copyright © 2013 Elsevier B.V. All rights reserved.

Left neglect dyslexia and the effect of stimulus duration.

PubMed

Arduino, Lisa S; Vallar, Giuseppe; Burani, Cristina

2006-01-01

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.

Spatiotemporal Pixelization to Increase the Recognition Score of Characters for Retinal Prostheses

PubMed Central

Kim, Hyun Seok; Park, Kwang Suk

2017-01-01

Most of the retinal prostheses use a head-fixed camera and a video processing unit. Some studies proposed various image processing methods to improve visual perception for patients. However, previous studies only focused on using spatial information. The present study proposes a spatiotemporal pixelization method mimicking fixational eye movements to generate stimulation images for artificial retina arrays by combining spatial and temporal information. Input images were sampled with a resolution that was four times higher than the number of pixel arrays. We subsampled this image and generated four different phosphene images. We then evaluated the recognition scores of characters by sequentially presenting phosphene images with varying pixel array sizes (6 × 6, 8 × 8 and 10 × 10) and stimulus frame rates (10 Hz, 15 Hz, 20 Hz, 30 Hz, and 60 Hz). The proposed method showed the highest recognition score at a stimulus frame rate of approximately 20 Hz. The method also significantly improved the recognition score for complex characters. This method provides a new way to increase practical resolution over restricted spatial resolution by merging the higher resolution image into high-frame time slots. PMID:29073735

Stimulus specificity and individual stereotypy of autonomic responses to motion stressors. M.S. Thesis

NASA Technical Reports Server (NTRS)

Morgan, M. G.

1985-01-01

Motion sickness research shows a lack of agreement regarding the contribution of the autonomic nervous system (ANS). The resolution of this question is exigent for Space Adaptation Syndrome, zero gravity sickness. A case is drawn for the necessity to apply a methodological approach that incorporates: (1) standardization of parameters in relation to the individual differences in variability and prestimulus levels; (2) a concern for patterning of responses; and (3) the physiological association with subjective reports. Vasomotor, heart rate, respiration rate, skin conductance and subjective reports of malaise were collected from 22 subjects while participating in three motion stressors; vertical acceleration, Coriolis stimulation, and combined optokinetic and Coriolis stimulation. The results demonstrate that ANS response patterns can be separated into three mutually exclusive components: (1) a generalized response to motion sickness; (2) a stimulus specific response to the type of stressor being presented; and (3) individualized stereotypical response patterns that are associated with subjective reports of malaise.

The touchscreen operant platform for assessing executive function in rats and mice

PubMed Central

Mar, Adam C.; Horner, Alexa E.; Nilsson, Simon R.O.; Alsiö, Johan; Kent, Brianne A.; Kim, Chi Hun; Holmes, Andrew; Saksida, Lisa M.; Bussey, Timothy J.

2014-01-01

Summary This protocol details a subset of assays developed within the touchscreen platform to measure aspects of executive function in rodents. Three main procedures are included: Extinction, measuring the rate and extent of curtailing a response that was previously, but is no longer, associated with reward; Reversal Learning, measuring the rate and extent of switching a response toward a visual stimulus that was previously not, but has become, associated with reward (and away from a visual stimulus that was previously, but is no longer, rewarded); and the 5-Choice Serial Reaction Time (5-CSRT) task, gauging the ability to selectively detect and appropriately respond to briefly presented, spatially unpredictable visual stimuli. These methods were designed to assess both complimentary and overlapping constructs including selective and divided visual attention, inhibitory control, flexibility, impulsivity and compulsivity. The procedures comprise part of a wider touchscreen test battery assessing cognition in rodents with high potential for translation to human studies. PMID:24051960

Task choice and semantic interference in picture naming.

PubMed

Piai, Vitória; Roelofs, Ardi; Schriefers, Herbert

2015-05-01

Evidence from dual-task performance indicates that speakers prefer not to select simultaneous responses in picture naming and another unrelated task, suggesting a response selection bottleneck in naming. In particular, when participants respond to tones with a manual response and name pictures with superimposed semantically related or unrelated distractor words, semantic interference in naming tends to be constant across stimulus onset asynchronies (SOAs) between the tone stimulus and the picture-word stimulus. In the present study, we examine whether semantic interference in picture naming depends on SOA in case of a task choice (naming the picture vs reading the word of a picture-word stimulus) based on tones. This situation requires concurrent processing of the tone stimulus and the picture-word stimulus, but not a manual response to the tones. On each trial, participants either named a picture or read aloud a word depending on the pitch of a tone, which was presented simultaneously with picture-word onset or 350 ms or 1000 ms before picture-word onset. Semantic interference was present with tone pre-exposure, but absent when tone and picture-word stimulus were presented simultaneously. Against the background of the available studies, these results support an account according to which speakers tend to avoid concurrent response selection, but can engage in other types of concurrent processing, such as task choices. Copyright © 2015 Elsevier B.V. All rights reserved.

Spontaneous activity in default-mode network predicts ascription of self-relatedness to stimuli.

PubMed

Qin, Pengmin; Grimm, Simone; Duncan, Niall W; Fan, Yan; Huang, Zirui; Lane, Timothy; Weng, Xuchu; Bajbouj, Malek; Northoff, Georg

2016-04-01

Spontaneous activity levels prior to stimulus presentation can determine how that stimulus will be perceived. It has also been proposed that such spontaneous activity, particularly in the default-mode network (DMN), is involved in self-related processing. We therefore hypothesised that pre-stimulus activity levels in the DMN predict whether a stimulus is judged as self-related or not. Participants were presented in the MRI scanner with a white noise stimulus that they were instructed contained their name or another. They then had to respond with which name they thought they heard. Regions where there was an activity level difference between self and other response trials 2 s prior to the stimulus being presented were identified. Pre-stimulus activity levels were higher in the right temporoparietal junction, the right temporal pole and the left superior temporal gyrus in trials where the participant responded that they heard their own name than trials where they responded that they heard another. Pre-stimulus spontaneous activity levels in particular brain regions, largely overlapping with the DMN, predict the subsequent judgement of stimuli as self-related. This extends our current knowledge of self-related processing and its apparent relationship with intrinsic brain activity in what can be termed a rest-self overlap. © The Author (2016). Published by Oxford University Press. For Permissions, please email: journals.permissions@oup.com.

Within-Subject Reversibility of Discriminative Function in the Composite-Stimulus Control of Behavior

ERIC Educational Resources Information Center

Weiss, Stanley J.; Kearns, David N.; Antoshina, Maria

2009-01-01

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…

Additive Effects of Stimulus Quality and Word Frequency on Eye Movements during Chinese Reading

ERIC Educational Resources Information Center

Liu, Pingping; Li, Xingshan; Han, Buxin

2015-01-01

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…

Stimulus probability effects in absolute identification.

PubMed

Kent, Christopher; Lamberts, Koen

2016-05-01

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 presentation probability on both proportion correct and response times. The effects were moderated by the ubiquitous stimulus position effect. The accuracy and response time data were predicted by an exemplar-based model of perceptual cognition (Kent & Lamberts, 2005). The bow in discriminability was also attenuated when presentation probability for middle items was relatively high, an effect that will constrain future model development. The study provides evidence for item-specific learning in absolute identification. Implications for other theories of absolute identification are discussed. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

Order of stimulus presentation influences children's acquisition in receptive identification tasks.

PubMed

Petursdottir, Anna Ingeborg; Aguilar, Gabriella

2016-03-01

Receptive identification is usually taught in matching-to-sample format, which entails the presentation of an auditory sample stimulus and several visual comparison stimuli in each trial. Conflicting recommendations exist regarding the order of stimulus presentation in matching-to-sample trials. The purpose of this study was to compare acquisition in receptive identification tasks under 2 conditions: when the sample was presented before the comparisons (sample first) and when the comparisons were presented before the sample (comparison first). Participants included 4 typically developing kindergarten-age boys. Stimuli, which included birds and flags, were presented on a computer screen. Acquisition in the 2 conditions was compared in an adapted alternating-treatments design combined with a multiple baseline design across stimulus sets. All participants took fewer trials to meet the mastery criterion in the sample-first condition than in the comparison-first condition. © 2015 Society for the Experimental Analysis of Behavior.

Contributions of retinal input and phenomenal representation of a fixation object to the saccadic gap effect.

PubMed

Ueda, Hiroshi; Takahashi, Kohske; Watanabe, Katsumi

2013-04-19

The saccadic "gap effect" refers to a phenomenon whereby saccadic reaction times (SRTs) are shortened by the removal of a visual fixation stimulus prior to target presentation. In the current study, we investigated whether the gap effect was influenced by retinal input of a fixation stimulus, as well as phenomenal permanence and/or expectation of the re-emergence of a fixation stimulus. In Experiment 1, we used an occluded fixation stimulus that was gradually hidden by a moving plate prior to the target presentation, which produced the impression that the fixation stimulus still remained and would reappear from behind the plate. We found that the gap effect was significantly weakened with the occluded fixation stimulus. However, the SRT with the occluded fixation stimulus was still shorter in comparison to when the fixation stimulus physically remained on the screen. In Experiment 2, we investigated whether this effect was due to phenomenal maintenance or expectation of the reappearance of the fixation stimulus; this was achieved by using occluding plates that were an identical color to the background screen, giving the impression of reappearance of the fixation stimulus but not of its maintenance. The result showed that the gap effect was still weakened by the same degree even without phenomenal maintenance of the fixation stimulus. These results suggest that the saccadic gap effect is modulated by both retinal input and subjective expectation of re-emergence of the fixation stimulus. In addition to oculomotor mechanisms, other components, such as attentional mechanisms, likely contribute to facilitation of the subsequent action. Copyright © 2013 Elsevier Ltd. All rights reserved.

A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance.

PubMed

von Trapp, Gardiner; Buran, Bradley N; Sen, Kamal; Semple, Malcolm N; Sanes, Dan H

2016-10-26

The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability of the neural response becomes smaller during task performance, thereby improving neural detection thresholds. Copyright © 2016 the authors 0270-6474/16/3611097-10$15.00/0.

A Decline in Response Variability Improves Neural Signal Detection during Auditory Task Performance

PubMed Central

Buran, Bradley N.; Sen, Kamal; Semple, Malcolm N.; Sanes, Dan H.

2016-01-01

The detection of a sensory stimulus arises from a significant change in neural activity, but a sensory neuron's response is rarely identical to successive presentations of the same stimulus. Large trial-to-trial variability would limit the central nervous system's ability to reliably detect a stimulus, presumably affecting perceptual performance. However, if response variability were to decrease while firing rate remained constant, then neural sensitivity could improve. Here, we asked whether engagement in an auditory detection task can modulate response variability, thereby increasing neural sensitivity. We recorded telemetrically from the core auditory cortex of gerbils, both while they engaged in an amplitude-modulation detection task and while they sat quietly listening to the identical stimuli. Using a signal detection theory framework, we found that neural sensitivity was improved during task performance, and this improvement was closely associated with a decrease in response variability. Moreover, units with the greatest change in response variability had absolute neural thresholds most closely aligned with simultaneously measured perceptual thresholds. Our findings suggest that the limitations imposed by response variability diminish during task performance, thereby improving the sensitivity of neural encoding and potentially leading to better perceptual sensitivity. SIGNIFICANCE STATEMENT The detection of a sensory stimulus arises from a significant change in neural activity. However, trial-to-trial variability of the neural response may limit perceptual performance. If the neural response to a stimulus is quite variable, then the response on a given trial could be confused with the pattern of neural activity generated when the stimulus is absent. Therefore, a neural mechanism that served to reduce response variability would allow for better stimulus detection. By recording from the cortex of freely moving animals engaged in an auditory detection task, we found that variability of the neural response becomes smaller during task performance, thereby improving neural detection thresholds. PMID:27798189

Temporal characteristics of gustatory responses in rat parabrachial neurons vary by stimulus and chemosensitive neuron type.

PubMed

Geran, Laura; Travers, Susan

2013-01-01

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.

Temporal Characteristics of Gustatory Responses in Rat Parabrachial Neurons Vary by Stimulus and Chemosensitive Neuron Type

PubMed Central

Geran, Laura; Travers, Susan

2013-01-01

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 500ms 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. PMID:24124597

Coding and Decoding with Adapting Neurons: A Population Approach to the Peri-Stimulus Time Histogram

PubMed Central

Naud, Richard; Gerstner, Wulfram

2012-01-01

The response of a neuron to a time-dependent stimulus, as measured in a Peri-Stimulus-Time-Histogram (PSTH), exhibits an intricate temporal structure that reflects potential temporal coding principles. Here we analyze the encoding and decoding of PSTHs for spiking neurons with arbitrary refractoriness and adaptation. As a modeling framework, we use the spike response model, also known as the generalized linear neuron model. Because of refractoriness, the effect of the most recent spike on the spiking probability a few milliseconds later is very strong. The influence of the last spike needs therefore to be described with high precision, while the rest of the neuronal spiking history merely introduces an average self-inhibition or adaptation that depends on the expected number of past spikes but not on the exact spike timings. Based on these insights, we derive a ‘quasi-renewal equation’ which is shown to yield an excellent description of the firing rate of adapting neurons. We explore the domain of validity of the quasi-renewal equation and compare it with other rate equations for populations of spiking neurons. The problem of decoding the stimulus from the population response (or PSTH) is addressed analogously. We find that for small levels of activity and weak adaptation, a simple accumulator of the past activity is sufficient to decode the original input, but when refractory effects become large decoding becomes a non-linear function of the past activity. The results presented here can be applied to the mean-field analysis of coupled neuron networks, but also to arbitrary point processes with negative self-interaction. PMID:23055914

QT dispersion and rate-corrected QT dispersion during electroconvulsive therapy in elderly patients.

PubMed

Yamaguchi, Shigeki; Nagao, Masaru; Ikeda, Tomohisa; Fukagawa, Daigo; Kimura, Yoshiyuki; Kitajima, Toshimitsu; Minami, Junichi

2011-09-01

Electroconvulsive therapy (ECT) induces increase of QT dispersion (QTD) and the rate-corrected QTD (QTcD), which are associated with increased risk of ventricular arrhythmias and cardiovascular mortality. The effects of electrical stimulus during ECT on QTD and QTcD in elderly patients are of considerable interest. The purpose of this study was to clarify the differential effects of electrical stimulus caused by ECT on interbeat interval, QT interval, the rate-corrected QT (QTc) interval, QTD, and the QTcD under propofol anesthesia between younger and elderly patients with major depression. Twenty younger psychiatric patients (aged 30-40 years) and 20 elderly patients (aged 65-75 years) scheduled for ECT were studied under propofol anesthesia. A 12-lead electrocardiogram was monitored to measure parameters. Muscle paralysis was achieved by administering 1-mg/kg succinylcholine intravenously, and the efficacy of ECT was determined by the tourniquet technique. The mean arterial pressure in the elderly was significantly higher than that of the younger patients from immediately to 2 minutes after electrical stimulus. The interbeat interval in the elderly was significantly lower than that of the younger patients from immediately to 1 minute after electrical stimulus. There was no statistically significant difference in the QT interval between the groups. The baseline value of QTc interval was higher than the normal limits, and the QTc interval in the elderly was significantly lower than that of the younger patients from immediately to 1 minute after electrical stimulus. The baseline value of QTD was higher than the normal limits, and the QTD in the elderly was significantly higher than that of the younger patients from immediately to 7 minutes after electrical stimulus. The baseline value of QTcD was higher than the normal limits, and the QTcD in the elderly was significantly higher than that of the younger patients from immediately to 7 minutes after electrical stimulus. The QTc interval, QTD, and QTcD may be higher than the normal limits before anesthesia in patients with major depression. The QTD and QTcD in the elderly, which are associated with increased risks of ventricular arrhythmias, are higher than those of the younger patients after electrical stimulus during ECT. Electrical stimulus may induce further increased risks of cardiac events in elderly patients.

Subliminal perception of complex visual stimuli.

PubMed

Ionescu, Mihai Radu

2016-01-01

Rationale: Unconscious perception of various sensory modalities is an active subject of research though its function and effect on behavior is uncertain. Objective: The present study tried to assess if unconscious visual perception could occur with more complex visual stimuli than previously utilized. Methods and Results: Videos containing slideshows of indifferent complex images with interspersed frames of interest of various durations were presented to 24 healthy volunteers. The perception of the stimulus was evaluated with a forced-choice questionnaire while awareness was quantified by self-assessment with a modified awareness scale annexed to each question with 4 categories of awareness. At values of 16.66 ms of stimulus duration, conscious awareness was not possible and answers regarding the stimulus were random. At 50 ms, nonrandom answers were coupled with no self-reported awareness suggesting unconscious perception of the stimulus. At larger durations of stimulus presentation, significantly correct answers were coupled with a certain conscious awareness. Discussion: At values of 50 ms, unconscious perception is possible even with complex visual stimuli. Further studies are recommended with a focus on a range of interest of stimulus duration between 50 to 16.66 ms.

Inseparability of Go and Stop in Inhibitory Control: Go Stimulus Discriminability Affects Stopping Behavior.

PubMed

Ma, Ning; Yu, Angela J

2016-01-01

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.

Multi-Variate EEG Analysis as a Novel Tool to Examine Brain Responses to Naturalistic Music Stimuli

PubMed Central

Sturm, Irene; Dähne, Sven; Blankertz, Benjamin; Curio, Gabriel

2015-01-01

Note onsets in music are acoustic landmarks providing auditory cues that underlie the perception of more complex phenomena such as beat, rhythm, and meter. For naturalistic ongoing sounds a detailed view on the neural representation of onset structure is hard to obtain, since, typically, stimulus-related EEG signatures are derived by averaging a high number of identical stimulus presentations. Here, we propose a novel multivariate regression-based method extracting onset-related brain responses from the ongoing EEG. We analyse EEG recordings of nine subjects who passively listened to stimuli from various sound categories encompassing simple tone sequences, full-length romantic piano pieces and natural (non-music) soundscapes. The regression approach reduces the 61-channel EEG to one time course optimally reflecting note onsets. The neural signatures derived by this procedure indeed resemble canonical onset-related ERPs, such as the N1-P2 complex. This EEG projection was then utilized to determine the Cortico-Acoustic Correlation (CACor), a measure of synchronization between EEG signal and stimulus. We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli’s average magnitudes of sharpness, spectral centroid, and rhythmic complexity. In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment. Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music. PMID:26510120

Multi-Variate EEG Analysis as a Novel Tool to Examine Brain Responses to Naturalistic Music Stimuli.

PubMed

Sturm, Irene; Dähne, Sven; Blankertz, Benjamin; Curio, Gabriel

2015-01-01

Note onsets in music are acoustic landmarks providing auditory cues that underlie the perception of more complex phenomena such as beat, rhythm, and meter. For naturalistic ongoing sounds a detailed view on the neural representation of onset structure is hard to obtain, since, typically, stimulus-related EEG signatures are derived by averaging a high number of identical stimulus presentations. Here, we propose a novel multivariate regression-based method extracting onset-related brain responses from the ongoing EEG. We analyse EEG recordings of nine subjects who passively listened to stimuli from various sound categories encompassing simple tone sequences, full-length romantic piano pieces and natural (non-music) soundscapes. The regression approach reduces the 61-channel EEG to one time course optimally reflecting note onsets. The neural signatures derived by this procedure indeed resemble canonical onset-related ERPs, such as the N1-P2 complex. This EEG projection was then utilized to determine the Cortico-Acoustic Correlation (CACor), a measure of synchronization between EEG signal and stimulus. We demonstrate that a significant CACor (i) can be detected in an individual listener's EEG of a single presentation of a full-length complex naturalistic music stimulus, and (ii) it co-varies with the stimuli's average magnitudes of sharpness, spectral centroid, and rhythmic complexity. In particular, the subset of stimuli eliciting a strong CACor also produces strongly coordinated tension ratings obtained from an independent listener group in a separate behavioral experiment. Thus musical features that lead to a marked physiological reflection of tone onsets also contribute to perceived tension in music.

Positive and negative affect produce opposing task-irrelevant stimulus preexposure effects.

PubMed

Lazar, Josef; Kaplan, Oren; Sternberg, Terri; Lubow, R E

2012-06-01

In three experiments, groups were exposed to either positive or negative affect video clips, after which they were presented with a series of task-irrelevant stimuli. In the subsequent test task, subjects were required to learn an association between the previously irrelevant stimulus and a consequence, and between a new stimulus and a consequence. Induced positive affect produced a latent inhibition effect (poorer evidence of learning with the previously irrelevant stimulus than with the novel stimulus). In opposition to this, induced negative affect resulted in better evidence of learning with a previously irrelevant stimulus than with a novel stimulus. In general, the opposing effects also were present in participants scoring high on self-report questionnaires of depression (Experiments 2 and 3). These unique findings were predicted and accounted for on the basis of two principles: (a) positive affect broadens the attentional field and negative affect contracts it; and (b) task-irrelevant stimuli are processed in two successive stages, the first encodes stimulus properties, and the second encodes stimulus relationships. The opposing influences of negative and positive mood on the processing of irrelevant stimuli have implications for the role of emotion in general theories of cognition, and possibly for resolving some of the inconsistent findings in research with schizophrenia patients.

Effects of auditory stimuli in the horizontal plane on audiovisual integration: an event-related potential study.

PubMed

Yang, Weiping; Li, Qi; Ochi, Tatsuya; Yang, Jingjing; Gao, Yulin; Tang, Xiaoyu; Takahashi, Satoshi; Wu, Jinglong

2013-01-01

This article aims to investigate whether auditory stimuli in the horizontal plane, particularly originating from behind the participant, affect audiovisual integration by using behavioral and event-related potential (ERP) measurements. In this study, visual stimuli were presented directly in front of the participants, auditory stimuli were presented at one location in an equidistant horizontal plane at the front (0°, the fixation point), right (90°), back (180°), or left (270°) of the participants, and audiovisual stimuli that include both visual stimuli and auditory stimuli originating from one of the four locations were simultaneously presented. These stimuli were presented randomly with equal probability; during this time, participants were asked to attend to the visual stimulus and respond promptly only to visual target stimuli (a unimodal visual target stimulus and the visual target of the audiovisual stimulus). A significant facilitation of reaction times and hit rates was obtained following audiovisual stimulation, irrespective of whether the auditory stimuli were presented in the front or back of the participant. However, no significant interactions were found between visual stimuli and auditory stimuli from the right or left. Two main ERP components related to audiovisual integration were found: first, auditory stimuli from the front location produced an ERP reaction over the right temporal area and right occipital area at approximately 160-200 milliseconds; second, auditory stimuli from the back produced a reaction over the parietal and occipital areas at approximately 360-400 milliseconds. Our results confirmed that audiovisual integration was also elicited, even though auditory stimuli were presented behind the participant, but no integration occurred when auditory stimuli were presented in the right or left spaces, suggesting that the human brain might be particularly sensitive to information received from behind than both sides.

Effects of Auditory Stimuli in the Horizontal Plane on Audiovisual Integration: An Event-Related Potential Study

PubMed Central

Yang, Weiping; Li, Qi; Ochi, Tatsuya; Yang, Jingjing; Gao, Yulin; Tang, Xiaoyu; Takahashi, Satoshi; Wu, Jinglong

2013-01-01

This article aims to investigate whether auditory stimuli in the horizontal plane, particularly originating from behind the participant, affect audiovisual integration by using behavioral and event-related potential (ERP) measurements. In this study, visual stimuli were presented directly in front of the participants, auditory stimuli were presented at one location in an equidistant horizontal plane at the front (0°, the fixation point), right (90°), back (180°), or left (270°) of the participants, and audiovisual stimuli that include both visual stimuli and auditory stimuli originating from one of the four locations were simultaneously presented. These stimuli were presented randomly with equal probability; during this time, participants were asked to attend to the visual stimulus and respond promptly only to visual target stimuli (a unimodal visual target stimulus and the visual target of the audiovisual stimulus). A significant facilitation of reaction times and hit rates was obtained following audiovisual stimulation, irrespective of whether the auditory stimuli were presented in the front or back of the participant. However, no significant interactions were found between visual stimuli and auditory stimuli from the right or left. Two main ERP components related to audiovisual integration were found: first, auditory stimuli from the front location produced an ERP reaction over the right temporal area and right occipital area at approximately 160–200 milliseconds; second, auditory stimuli from the back produced a reaction over the parietal and occipital areas at approximately 360–400 milliseconds. Our results confirmed that audiovisual integration was also elicited, even though auditory stimuli were presented behind the participant, but no integration occurred when auditory stimuli were presented in the right or left spaces, suggesting that the human brain might be particularly sensitive to information received from behind than both sides. PMID:23799097

A Neural Signature Encoding Decisions under Perceptual Ambiguity

PubMed Central

Sun, Sai; Yu, Rongjun

2017-01-01

Abstract People often make perceptual decisions with ambiguous information, but it remains unclear whether the brain has a common neural substrate that encodes various forms of perceptual ambiguity. Here, we used three types of perceptually ambiguous stimuli as well as task instructions to examine the neural basis for both stimulus-driven and task-driven perceptual ambiguity. We identified a neural signature, the late positive potential (LPP), that encoded a general form of stimulus-driven perceptual ambiguity. In addition to stimulus-driven ambiguity, the LPP was also modulated by ambiguity in task instructions. To further specify the functional role of the LPP and elucidate the relationship between stimulus ambiguity, behavioral response, and the LPP, we employed regression models and found that the LPP was specifically associated with response latency and confidence rating, suggesting that the LPP encoded decisions under perceptual ambiguity. Finally, direct behavioral ratings of stimulus and task ambiguity confirmed our neurophysiological findings, which could not be attributed to differences in eye movements either. Together, our findings argue for a common neural signature that encodes decisions under perceptual ambiguity but is subject to the modulation of task ambiguity. Our results represent an essential first step toward a complete neural understanding of human perceptual decision making. PMID:29177189

Startle Auditory Stimuli Enhance the Performance of Fast Dynamic Contractions

PubMed Central

Fernandez-Del-Olmo, Miguel; Río-Rodríguez, Dan; Iglesias-Soler, Eliseo; Acero, Rafael M.

2014-01-01

Fast reaction times and the ability to develop a high rate of force development (RFD) are crucial for sports performance. However, little is known regarding the relationship between these parameters. The aim of this study was to investigate the effects of auditory stimuli of different intensities on the performance of a concentric bench-press exercise. Concentric bench-presses were performed by thirteen trained subjects in response to three different conditions: a visual stimulus (VS); a visual stimulus accompanied by a non-startle auditory stimulus (AS); and a visual stimulus accompanied by a startle auditory stimulus (SS). Peak RFD, peak velocity, onset movement, movement duration and electromyography from pectoralis and tricep muscles were recorded. The SS condition induced an increase in the RFD and peak velocity and a reduction in the movement onset and duration, in comparison with the VS and AS condition. The onset activation of the pectoralis and tricep muscles was shorter for the SS than for the VS and AS conditions. These findings point out to specific enhancement effects of loud auditory stimulation on the rate of force development. This is of relevance since startle stimuli could be used to explore neural adaptations to resistance training. PMID:24489967

A Neural Signature Encoding Decisions under Perceptual Ambiguity.

PubMed

Sun, Sai; Yu, Rongjun; Wang, Shuo

2017-01-01

People often make perceptual decisions with ambiguous information, but it remains unclear whether the brain has a common neural substrate that encodes various forms of perceptual ambiguity. Here, we used three types of perceptually ambiguous stimuli as well as task instructions to examine the neural basis for both stimulus-driven and task-driven perceptual ambiguity. We identified a neural signature, the late positive potential (LPP), that encoded a general form of stimulus-driven perceptual ambiguity. In addition to stimulus-driven ambiguity, the LPP was also modulated by ambiguity in task instructions. To further specify the functional role of the LPP and elucidate the relationship between stimulus ambiguity, behavioral response, and the LPP, we employed regression models and found that the LPP was specifically associated with response latency and confidence rating, suggesting that the LPP encoded decisions under perceptual ambiguity. Finally, direct behavioral ratings of stimulus and task ambiguity confirmed our neurophysiological findings, which could not be attributed to differences in eye movements either. Together, our findings argue for a common neural signature that encodes decisions under perceptual ambiguity but is subject to the modulation of task ambiguity. Our results represent an essential first step toward a complete neural understanding of human perceptual decision making.

Simultaneous perceptual and response biases on sequential face attractiveness judgments

PubMed Central

Pegors, Teresa K.; Mattar, Marcelo G.; Bryan, Peter B.; Epstein, Russell A.

2015-01-01

Face attractiveness is a social characteristic that we often use to make first-pass judgments about the people around us. However, these judgments are highly influenced by our surrounding social world, and researchers still understand little about the mechanisms underlying these influences. In a series of three experiments, we used a novel sequential rating paradigm that enabled us to measure biases on attractiveness judgments from the previous face and the previous rating. Our results revealed two simultaneous and opposing influences on face attractiveness judgments that arise from our past experience of faces: a response bias in which attractiveness ratings shift towards a previously given rating, and a stimulus bias in which attractiveness ratings shift away from the mean attractiveness of the previous face. Furthermore, we provide evidence that the contrastive stimulus bias (but not the assimilative response bias) is strengthened by increasing the duration of the previous stimulus, suggesting an underlying perceptual mechanism. These results demonstrate that judgments of face attractiveness are influenced by information from our evaluative and perceptual history and that these influences have measurable behavioral effects over the course of just a few seconds. PMID:25867223

Visually evoked changes in the rat retinal blood flow measured with Doppler optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Tan, Bingyao; Mason, Erik; MacLellan, Ben; Bizheva, Kostadinka

2017-02-01

Visually evoked changes of retinal blood flow can serve as an important research tool to investigate eye disease such as glaucoma and diabetic retinopathy. In this study we used a combined, research-grade, high-resolution Doppler OCT+ERG system to study changes in the retinal blood flow (RBF) and retinal neuronal activity in response to visual stimuli of different intensities, durations and type (flicker vs single flash). Specifically, we used white light stimuli of 10 ms and 200 ms single flash, 1s and 2s for flickers stimuli of 20% duty cycle. The study was conducted in-vivo in pigmented rats. Both single flash (SF) and flicker stimuli caused increase in the RBF. The 10 ms SF stimulus did not generate any consistent measurable response, while the 200 ms SF of the same intensity generated 4% change in the RBF peaking at 1.5 s after the stimulus onset. Single flash stimuli introduced 2x smaller change in RBF and 30% earlier RBF peak response compared to flicker stimuli of the same intensity and duration. Doubling the intensity of SF or flicker stimuli increased the RBF peak magnitude by 1.5x. Shortening the flicker stimulus duration by 2x increased the RBF recovery rate by 2x, however, had no effect on the rate of RBF change from baseline to peak.

Duration of stimulus presentation and screening for perceptual disabilities.

PubMed

Rohr, M E; Ayers, J B

1975-02-01

This study examined the effects of increasing the stimulus-presentation time of a motion picture test for identifying perceptual disabilities in the performance of Ss in regular first and fourth grade classrooms and on a sample of Ss in special education classes who had been identified as having varying degrees of perceptual deficiencies. The length of stimulus presentation increased the total performance of Ss on the motion picture test but did not add to the value of the instrument as a screening device.

Stimulus-reinforcer relations established during training determine resistance to extinction and relapse via reinstatement.

PubMed

Bai, John Y H; Jonas Chan, C K; Elliffe, Douglas; Podlesnik, Christopher A

2016-11-01

The baseline rate of a reinforced target response decreases with the availability of response-independent sources of alternative reinforcement; however, resistance to disruption and relapse increases. Because many behavioral treatments for problem behavior include response-dependent reinforcement of alternative behavior, the present study assessed whether response-dependent alternative reinforcement also decreases baseline response rates but increases resistance to extinction and relapse. We reinforced target responding at equal rates across two components of a multiple schedule with pigeons. We compared resistance to extinction and relapse via reinstatement of (1) a target response trained concurrently with a reinforced alternative response in one component with (2) a target response trained either concurrently or in separate components from the alternative response across conditions. Target response rates trained alone in baseline were higher but resistance to extinction and relapse via reinstatement tests were greater after training concurrently with the alternative response. In another assessment, training target and alternative responding together, but separating them during extinction and reinstatement tests, produced equal resistance to extinction and relapse. Together, these findings are consistent with behavioral momentum theory-operant response-reinforcer relations determined baseline response rates but Pavlovian stimulus-reinforcer relations established during training determined resistance to extinction and relapse. These findings imply that reinforcing alternative behavior to treat problem behavior could initially reduce rates but increase persistence. © 2016 Society for the Experimental Analysis of Behavior.

Finding an emotional face in a crowd: emotional and perceptual stimulus factors influence visual search efficiency.

PubMed

Lundqvist, Daniel; Bruce, Neil; Öhman, Arne

2015-01-01

In this article, we examine how emotional and perceptual stimulus factors influence visual search efficiency. In an initial task, we run a visual search task, using a large number of target/distractor emotion combinations. In two subsequent tasks, we then assess measures of perceptual (rated and computational distances) and emotional (rated valence, arousal and potency) stimulus properties. In a series of regression analyses, we then explore the degree to which target salience (the size of target/distractor dissimilarities) on these emotional and perceptual measures predict the outcome on search efficiency measures (response times and accuracy) from the visual search task. The results show that both emotional and perceptual stimulus salience contribute to visual search efficiency. The results show that among the emotional measures, salience on arousal measures was more influential than valence salience. The importance of the arousal factor may be a contributing factor to contradictory history of results within this field.

Stimulus rate increases lateralisation in linguistic and non-linguistic tasks measured by functional transcranial Doppler sonography

PubMed Central

Payne, Heather; Gutierrez-Sigut, Eva; Subik, Joanna; Woll, Bencie; MacSweeney, Mairéad

2016-01-01

Studies to date that have used fTCD to examine language lateralisation have predominantly used word or sentence generation tasks. Here we sought to further assess the sensitivity of fTCD to language lateralisation by using a metalinguistic task which does not involve novel speech generation: rhyme judgement in response to written words. Line array judgement was included as a non-linguistic visuospatial task to examine the relative strength of left and right hemisphere lateralisation within the same individuals when output requirements of the tasks are matched. These externally paced tasks allowed us to manipulate the number of stimuli presented to participants and thus assess the influence of pace on the strength of lateralisation. In Experiment 1, 28 right-handed adults participated in rhyme and line array judgement tasks and showed reliable left and right lateralisation at the group level for each task, respectively. In Experiment 2 we increased the pace of the tasks, presenting more stimuli per trial. We measured laterality indices (LIs) from 18 participants who performed both linguistic and non-linguistic judgement tasks during the original ‘slow’ presentation rate (5 judgements per trial) and a fast presentation rate (10 judgements per trial). The increase in pace led to increased strength of lateralisation in both the rhyme and line conditions. Our results demonstrate for the first time that fTCD is sensitive to the left lateralised processes involved in metalinguistic judgements. Our data also suggest that changes in the strength of language lateralisation, as measured by fTCD, are not driven by articulatory demands alone. The current results suggest that at least one aspect of task difficulty, the pace of stimulus presentation, influences the strength of lateralisation during both linguistic and non-linguistic tasks. PMID:25908491

Scopolamine effects on visual discrimination: modifications related to stimulus control

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

Evans, H.L.

1975-01-01

Stumptail monkeys (Macaca arctoides) performed a discrete trial, three-choice visual discrimination. The discrimination behavior was controlled by the shape of the visual stimuli. Strength of the stimuli in controlling behavior was systematically related to a physical property of the stimuli, luminance. Low luminance provided weak control, resulting in a low accuracy of discrimination, a low response probability and maximal sensitivity to scopolamine (7.5-60 ..mu..g/kg). In contrast, high luminance provided strong control of behavior and attenuated the effects of scopolamine. Methylscopolamine had no effect in doses of 30 to 90 ..mu..g/kg. Scopolamine effects resembled the effects of reducing stimulus control inmore » undrugged monkeys. Since behavior under weak control seems to be especially sensitive to drugs, manipulations of stimulus control may be particularly useful whenever determination of the minimally-effective dose is important, as in behavioral toxicology. Present results are interpreted as specific visual effects of the drug, since nonsensory factors such as base-line response rate, reinforcement schedule, training history, motor performance and motivation were controlled. Implications for state-dependent effects of drugs are discussed.« less

Time and Associative Learning.

PubMed

Balsam, Peter D; Drew, Michael R; Gallistel, C R

2010-01-01

In a basic associative learning paradigm, learning is said to have occurred when the conditioned stimulus evokes an anticipatory response. This learning is widely believed to depend on the contiguous presentation of conditioned and unconditioned stimulus. However, what it means to be contiguous has not been rigorously defined. Here we examine the empirical bases for these beliefs and suggest an alternative view based on the hypothesis that learning about the temporal relationships between events determines the speed of emergence, vigor and form of conditioned behavior. This temporal learning occurs very rapidly and prior to the appearance of the anticipatory response. The temporal relations are learned even when no anticipatory response is evoked. The speed with which an anticipatory response emerges is proportional to the informativeness of the predictive cue (CS) regarding the rate of occurrence of the predicted event (US). This analysis gives an account of what we mean by "temporal pairing" and is in accord with the data on speed of acquisition and basic findings in the cue competition literature. In this account, learning depends on perceiving and encoding temporal regularities rather than stimulus contiguities.

Time and Associative Learning

PubMed Central

Balsam, Peter D; Drew, Michael R.; Gallistel, C.R.

2010-01-01

In a basic associative learning paradigm, learning is said to have occurred when the conditioned stimulus evokes an anticipatory response. This learning is widely believed to depend on the contiguous presentation of conditioned and unconditioned stimulus. However, what it means to be contiguous has not been rigorously defined. Here we examine the empirical bases for these beliefs and suggest an alternative view based on the hypothesis that learning about the temporal relationships between events determines the speed of emergence, vigor and form of conditioned behavior. This temporal learning occurs very rapidly and prior to the appearance of the anticipatory response. The temporal relations are learned even when no anticipatory response is evoked. The speed with which an anticipatory response emerges is proportional to the informativeness of the predictive cue (CS) regarding the rate of occurrence of the predicted event (US). This analysis gives an account of what we mean by “temporal pairing” and is in accord with the data on speed of acquisition and basic findings in the cue competition literature. In this account, learning depends on perceiving and encoding temporal regularities rather than stimulus contiguities. PMID:21359131

Analysis of the dynamics of renal vascular resistance and urine flow rate in the cat following electrical stimulation of the renal nerves.

PubMed

Celler, B G; Stella, A; Golin, R; Zanchetti, A

1996-08-01

In ten sino aortic denervated, vagotomized and aneasthetized cats, renal efferent nerves were stimulated for 30 s with trains of constant current pulses at frequencies in the range 5-30 Hz. The arterial pressure, heart rate, urine flow rate (electronic drop counter) and renal blood flow (electromagnetic technique) were recorded. Subsequent computer processing gave the true means of renal artery pressure (MRAP) and renal blood flow (MRBF) and hence the renal vascular resistance (MRVR), over each cardiac cycle. Recovery of MRVR after the end of stimulation exhibited two distinct time constants. The fast component had a time constant of 2.03 +/- 0.26 s and represented 60.2 +/- 1.71% of the recovery. The time constant of the slower component was 14.1 +/- 1.9 s and represented 36.0 +/- 1.6% of the recovery. The relationship between MRVR and stimulus frequency was sigmoidal with maximum sensitivity at stimulus frequencies of 12.6 +/- 0.76 Hz. Changes in urine flow rate, in contrast, followed a hyperbolic function with maximum response sensitivity occurring at very low stimulus frequencies. Changes in urine flow rate were 50% complete at stimulus frequencies of 5 Hz. Identification of two distinct components in the relaxation phase of renal vascular resistance leads to a reasonable hypothesis that 60% of total renal vascular resistance may lie proximal to the glomerulus, whereas 36% may be accounted for by the efferent arterioles.

Differential effects of ongoing EEG beta and theta power on memory formation

PubMed Central

Scholz, Sebastian; Schneider, Signe Luisa

2017-01-01

Recently, elevated ongoing pre-stimulus beta power (13–17 Hz) at encoding has been associated with subsequent memory formation for visual stimulus material. It is unclear whether this activity is merely specific to visual processing or whether it reflects a state facilitating general memory formation, independent of stimulus modality. To answer that question, the present study investigated the relationship between neural pre-stimulus oscillations and verbal memory formation in different sensory modalities. For that purpose, a within-subject design was employed to explore differences between successful and failed memory formation in the visual and auditory modality. Furthermore, associative memory was addressed by presenting the stimuli in combination with background images. Results revealed that similar EEG activity in the low beta frequency range (13–17 Hz) is associated with subsequent memory success, independent of stimulus modality. Elevated power prior to stimulus onset differentiated successful from failed memory formation. In contrast, differential effects between modalities were found in the theta band (3–7 Hz), with an increased oscillatory activity before the onset of later remembered visually presented words. In addition, pre-stimulus theta power dissociated between successful and failed encoding of associated context, independent of the stimulus modality of the item itself. We therefore suggest that increased ongoing low beta activity reflects a memory promoting state, which is likely to be moderated by modality-independent attentional or inhibitory processes, whereas high ongoing theta power is suggested as an indicator of the enhanced binding of incoming interlinked information. PMID:28192459

Stimulus function in simultaneous discrimination1

PubMed Central

Biederman, Gerald B.

1968-01-01

In discrimination learning, the negativity of the stimulus correlated with nonreinforcement (S−) declines after 100 training trials while the stimulus correlated with reinforcement (S+) is paradoxically more positive with lesser amounts of discrimination training. Training subjects on two simultaneous discrimination tasks revealed a within-subjects overlearning reversal effect, where a more-frequently presented discrimination problem was better learned in reversal than was a discrimination problem presented less frequently during training. PMID:5672254

Variables influencing stimulus overselectivity and "tunnel vision" in developmentally delayed children.

PubMed

Rincover, A; Ducharme, J M

1987-01-01

Three variables (diagnosis, location of cues, and MA of learners) influencing stimulus control and stimulus overselectivity in autistic children were assessed. Eight autistic and 8 intellectually average children, matched on MA, were trained on two discrimination tasks; one task contained two "within-stimulus" (i.e., physically connected) cues; the other contained the same two cues presented "extra-stimulus" (i.e., physically separate). Generalization gradients were used following training to measure the degree of stimulus control acquired by each cue. Results showed: autistic subjects tended to respond overselectively only in the extra-stimulus condition; MA was positively correlated with breadth of learning; and when autistic children were overselective to one cue, some stimulus control was also acquired by the second cue. The notion of tunnel vision was discussed, as it may represent a "keystone" deficit interfering with stimulus control and learning by autistic children.

Brain computer interface to enhance episodic memory in human participants

PubMed Central

Burke, John F.; Merkow, Maxwell B.; Jacobs, Joshua; Kahana, Michael J.

2015-01-01

Recent research has revealed that neural oscillations in the theta (4–8 Hz) and alpha (9–14 Hz) bands are predictive of future success in memory encoding. Because these signals occur before the presentation of an upcoming stimulus, they are considered stimulus-independent in that they correlate with enhanced memory encoding independent of the item being encoded. Thus, such stimulus-independent activity has important implications for the neural mechanisms underlying episodic memory as well as the development of cognitive neural prosthetics. Here, we developed a brain computer interface (BCI) to test the ability of such pre-stimulus activity to modulate subsequent memory encoding. We recorded intracranial electroencephalography (iEEG) in neurosurgical patients as they performed a free recall memory task, and detected iEEG theta and alpha oscillations that correlated with optimal memory encoding. We then used these detected oscillatory changes to trigger the presentation of items in the free recall task. We found that item presentation contingent upon the presence of pre-stimulus theta and alpha oscillations modulated memory performance in more sessions than expected by chance. Our results suggest that an electrophysiological signal may be causally linked to a specific behavioral condition, and contingent stimulus presentation has the potential to modulate human memory encoding. PMID:25653605

A further test of sequential-sampling models that account for payoff effects on response bias in perceptual decision tasks.

PubMed

Diederich, Adele

2008-02-01

Recently, Diederich and Busemeyer (2006) evaluated three hypotheses formulated as particular versions of a sequential-sampling model to account for the effects of payoffs in a perceptual decision task with time constraints. The bound-change hypothesis states that payoffs affect the distance of the starting position of the decision process to each decision bound. The drift-rate-change hypothesis states that payoffs affect the drift rate of the decision process. The two-stage-processing hypothesis assumes two processes, one for processing payoffs and another for processing stimulus information, and that on a given trial, attention switches from one process to the other. The latter hypothesis gave the best account of their data. The present study investigated two questions: (1) Does the experimental setting influence decisions, and consequently affect the fits of the hypotheses? A task was conducted in two experimental settings--either the time limit or the payoff matrix was held constant within a given block of trials, using three different payoff matrices and four different time limits--in order to answer this question. (2) Could it be that participants neglect payoffs on some trials and stimulus information on others? To investigate this idea, a further hypothesis was considered, the mixture-of-processes hypothesis. Like the two-stage-processing hypothesis, it postulates two processes, one for payoffs and another for stimulus information. However, it differs from the previous hypothesis in assuming that on a given trial exactly one of the processes operates, never both. The present design had no effect on choice probability but may have affected choice response times (RTs). Overall, the two-stage-processing hypothesis gave the best account, with respect both to choice probabilities and to observed mean RTs and mean RT patterns within a choice pair.

Trading off switch costs and stimulus availability benefits: An investigation of voluntary task-switching behavior in a predictable dynamic multitasking environment.

PubMed

Mittelstädt, Victor; Miller, Jeff; Kiesel, Andrea

2018-03-09

In the present study, we introduce a novel, self-organized task-switching paradigm that can be used to study more directly the determinants of switching. Instead of instructing participants to randomly switch between tasks, as in the classic voluntary task-switching paradigm (Arrington & Logan, 2004), we instructed participants to optimize their task performance in a voluntary task-switching environment in which the stimulus associated with the previously selected task appeared in each trial after a delay. Importantly, the stimulus onset asynchrony (SOA) increased further with each additional repetition of this task, whereas the stimulus needed for a task switch was always immediately available. We conducted two experiments with different SOA increments (i.e., Exp. 1a = 50 ms, Exp. 1b = 33 ms) to see whether this procedure would induce switching behavior, and we explored how people trade off switch costs against the increasing availability of the stimulus needed for a task repetition. We observed that participants adapted their behavior to the different task environments (i.e., SOA increments) and that participants switched tasks when the SOA in task switches approximately matched the switch costs. Moreover, correlational analyses indicated relations between individual switch costs and individual switch rates across participants. Together, these results demonstrate that participants were sensitive to the increased availability of switch stimuli in deciding whether to switch or to repeat, which in turn demonstrates flexible adaptive task selection behavior. We suggest that performance limitations in task switching interact with the task environment to influence switching behavior.

Stimulus control by 5methoxy-N,N-dimethyltryptamine in wild-type and CYP2D6-humanized mice

PubMed Central

Winter, J. C.; Amorosi, D. J.; Rice, Kenner C.; Cheng, Kejun; Yu, Ai-Ming

2011-01-01

In previous studies we have observed that, in comparison with wild type mice, Tg-CYP2D6 mice have increased serum levels of bufotenine [5-hydroxy-N,N-dimethyltryptamine] following the administration of 5-MeO-DMT. Furthermore, following the injection of 5-MeO-DMT, harmaline was observed to increase serum levels of bufotenine and 5-MeO-DMT in both wild-type and Tg-CYP2D6 mice. In the present investigation, 5-MeO-DMT-induced stimulus control was established in wild-type and Tg-CYP2D6 mice. The two groups did not differ in their rate of acquisition of stimulus control. When tested with bufotenine, no 5-MeO-DMT-appropriate responding was observed. In contrast, the more lipid soluble analog of bufotenine, acetylbufotenine, was followed by an intermediate level of responding. The combination of harmaline with 5-MeO-DMT yielded a statistically significant increase in 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice; a comparable increase occurred in wild-type mice. In addition, it was noted that harmaline alone was followed by a significant degree of 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice. It is concluded that wild-type and Tg-CYPD2D6 mice do not differ in terms of acquisition of stimulus control by 5-MeO-DMT or in their response to bufotenine and acetylbufotenine. In both groups of mice, harmaline was found to enhance the stimulus effects of 5-MeO-DMT. PMID:21624387

Synchronous imaging of the pulse response of the ciliary muscle and lens with SD-OCT (Conference Presentation)

NASA Astrophysics Data System (ADS)

Chang, Yu-Cherng; Pham, Alex; Williams, Siobhan; Alawa, Karam A.; de Freitas, Carolina; Ruggeri, Marco; Parel, Jean-Marie A.; Manns, Fabrice

2017-02-01

Purpose: To determine the dynamic interaction between ciliary muscle and lens during accommodation and disaccommodation through synchronous imaging of ciliary muscle and lens response to pulse stimulus Methods: The ciliary muscle and lens were imaged simultaneously in a 33 year old subject responding to a 4D pulse stimulus (accommodative stimulus at 1.7 s, disaccommodative stimulus at 7.7 s) using an existing imaging system (Ruggeri et al, 2016) consisting of an Anterior Segment Optical Coherence Tomography system, Ciliary Muscle Optical Coherence Tomography system, and custom-built accommodation module. OCT images were recorded at an effective frame rate of 13.0 frames per second for a total scan time of 11.5 s. An automated segmentation algorithm was applied to images of the anterior segment to detect the boundaries of the cornea and lens, from which lens thickness was extracted. Segmentation of the ciliary muscle was performed manually and then corrected for distortion due to refraction of the beam to obtain measurements of thicknesses at the apex and fixed distances from the scleral spur. Results: The dynamic biometric response to a pulse stimulus at 4D was determined for both the ciliary muscle and lens, suggesting the ciliary muscle and lens interact differently in accommodation and disaccommodation. Conclusions: The study introduces new data and analyses of the ciliary muscle and lens interaction during a complete accommodative response from the relaxed to the accommodated state and back, providing insight into the interplay between individual elements in the accommodative system and how their relationships may change with age.

Artifactual responses when recording auditory steady-state responses.

PubMed

Small, Susan A; Stapells, David R

2004-12-01

The goal of this study was to investigate, in hearing-impaired participants who could not hear the stimuli, the possibility of artifactual auditory steady-state responses (ASSRs) when stimuli are presented at high intensities. ASSRs to single (60 dB HL) and multiple (20 to 50 dB HL; 500 to 4000 Hz) bone-conduction stimuli as well as single 114 to 120 dB HL air-conduction stimuli, were obtained using the Rotman MASTER system, using analog-to-digital (A/D) conversion rates of 500, 1000, and 1250 Hz. Responses (p < 0.05) were considered artifactual when their numbers exceeded that expected by chance. In some conditions, we also obtained ASSRs to "alternated" stimuli (stimuli inverted and ASSRs to the two polarities averaged). A total of 17 subjects were tested. Bone conduction results: 500 Hz A/D rate: Large-amplitude (43 to 1558 nV) artifactual ASSRs were seen at 40 and 50 dB HL for the 500 Hz carrier frequency. Smaller responses (28 to 53 nV) were also recorded at 20 dB HL for the 500 Hz carrier frequency. Artifactual ASSRs (17 to 62 nV) were seen at 40 dB HL and above for the 1000 Hz carrier frequency and at 50 dB HL for the 2000 Hz carrier frequency. Alternating the stimulus polarity decreased the amplitude and occurrence of these artifactual responses but did not eliminate responses for the 500 Hz carrier frequency at 40 dB HL and above. No artifactual responses were recorded for 4000 Hz stimuli for any condition. 1000 Hz A/D rate: Artifactual ASSRs (15 to 523 nV) were seen at 50 dB HL and above for the 500 Hz carrier frequency and 40 dB HL and above for the 1000 Hz carrier frequency. Artifactual responses were also obtained at 50 dB HL for a 2000 Hz carrier frequency but not at lower levels. Artifactual responses were not seen for the 4000 Hz carrier frequency. Alternating the stimulus polarity removed the responses for the 1000 and 2000 Hz carrier frequencies but did not change the results for the 500 Hz carrier frequency. 1250 Hz A/D rate: Artifactual ASSRs (16 to 220 nV) were seen at 50 dB HL and above for the 500 Hz carrier frequency and 60 dB HL and above for the 1000 Hz carrier frequency. Alternating the stimulus polarity removed the responses for the 1000 Hz carrier frequency but did not change the results for the 500 Hz carrier frequency. There were no artifactual responses at 2000 and 4000 Hz. Air conduction results: 500 Hz A/D rate: Artifactual ASSRs (49 to 153 nV) were seen for 114 to 120 dB HL stimuli for 500 and 1000 Hz carrier frequencies. Alternating the stimulus polarity removed these responses. There were no artifactual responses at 2000 and 4000 Hz. 1000 and 1250 Hz A/D rates: Artifactual ASSRs (19 to 55 nV) were seen for a 120 dB HL stimulus for a 1000 Hz carrier. Alternating the stimulus polarity removed these responses. High-intensity air- or bone-conduction stimuli can produce spurious ASSRs, especially for 500 and 1000 Hz carrier frequencies. High-amplitude stimulus artifact can result in energy that is aliased to exactly the modulation frequency. Choice of signal conditioning (electroencephalogram filter slope and low-pass cutoff) and processing (A/D rate) can avoid spurious responses due to aliasing. However, artifactual responses due to other causes may still occur for bone-conduction stimuli 50 dB HL and higher (and possibly for high-level air conduction). Because the phases of these spurious responses do not invert with inversion of stimulus, the possibility of nonauditory physiologic responses cannot be ruled out. The clinical implications of these results are that artifactual responses may occur for any patient for bone-conduction stimuli at levels greater than 40 dB HL and for high-intensity air-conduction stimuli used to assess patients with profound hearing loss.

Critical role of foreground stimuli in perceiving visually induced self-motion (vection).

PubMed

Nakamura, S; Shimojo, S

1999-01-01

The effects of a foreground stimulus on vection (illusory perception of self-motion induced by a moving background stimulus) were examined in two experiments. The experiments reveal that the presentation of a foreground pattern with a moving background stimulus may affect vection. The foreground stimulus facilitated vection strength when it remained stationary or moved slowly in the opposite direction to that of the background stimulus. On the other hand, there was a strong inhibition of vection when the foreground stimulus moved slowly with, or quickly against, the background. These results suggest that foreground stimuli, as well as background stimuli, play an important role in perceiving self-motion.

Effects of a sexy appearance on perceived competence of women.

PubMed

Wookey, Melissa L; Graves, Nell A; Butler, J Corey

2009-02-01

The present study replicates P. Glick, S. Larsen, C. Johnson, and H. Branstiter's (2005) previous research showing that a sexy appearance may be detrimental to women in high-status jobs. The authors used a larger sample and different stimulus materials and evaluation measures. As in the original experiment, participants rated sexually and professionally dressed women in both low- and high-status positions on perceived ability. The results were consistent with the original study and showed that high-status, sexually dressed women receive lower ratings in competence.

Human Fetal Behavior: 100 Years of Study.

ERIC Educational Resources Information Center

Kisilevsky, B. S.; Low, J. A.

1998-01-01

Reviews literature on human fetal behavior. Includes descriptions of coupling of body movements and fetal heart rate and behavior maturation from conception to term. Discusses use of stimulus-induced behavior to examine sensory and cognitive development, and spontaneous and stimulus-induced behavior to assess fetal well-being. Notes research focus…

Stimulus sensitive gel with radioisotope and methods of making

DOEpatents

Weller, Richard E.; Lind, Michael A.; Fisher, Darrell R.; Gutowska, Anna; Campbell, Allison A.

2005-03-22

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.

Stimulus sensitive gel with radioisotope and methods of making

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

Weller, Richard E; Lind, Michael A; Fisher, Darrell R

2001-10-02

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 withmore » 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.« less

Performance improvement of ERP-based brain-computer interface via varied geometric patterns.

PubMed

Ma, Zheng; Qiu, Tianshuang

2017-12-01

Recently, many studies have been focusing on optimizing the stimulus of an event-related potential (ERP)-based brain-computer interface (BCI). However, little is known about the effectiveness when increasing the stimulus unpredictability. We investigated a new stimulus type of varied geometric pattern where both complexity and unpredictability of the stimulus are increased. The proposed and classical paradigms were compared in within-subject experiments with 16 healthy participants. Results showed that the BCI performance was significantly improved for the proposed paradigm, with an average online written symbol rate increasing by 138% comparing with that of the classical paradigm. Amplitudes of primary ERP components, such as N1, P2a, P2b, N2, were also found to be significantly enhanced with the proposed paradigm. In this paper, a novel ERP BCI paradigm with a new stimulus type of varied geometric pattern is proposed. By jointly increasing the complexity and unpredictability of the stimulus, the performance of an ERP BCI could be considerably improved.

Gender differences in emotion recognition: Impact of sensory modality and emotional category.

PubMed

Lambrecht, Lena; Kreifelts, Benjamin; Wildgruber, Dirk

2014-04-01

Results from studies on gender differences in emotion recognition vary, depending on the types of emotion and the sensory modalities used for stimulus presentation. This makes comparability between different studies problematic. This study investigated emotion recognition of healthy participants (N = 84; 40 males; ages 20 to 70 years), using dynamic stimuli, displayed by two genders in three different sensory modalities (auditory, visual, audio-visual) and five emotional categories. The participants were asked to categorise the stimuli on the basis of their nonverbal emotional content (happy, alluring, neutral, angry, and disgusted). Hit rates and category selection biases were analysed. Women were found to be more accurate in recognition of emotional prosody. This effect was partially mediated by hearing loss for the frequency of 8,000 Hz. Moreover, there was a gender-specific selection bias for alluring stimuli: Men, as compared to women, chose "alluring" more often when a stimulus was presented by a woman as compared to a man.

Evaluative Conditioning Induces Changes in Sound Valence

PubMed Central

Bolders, Anna C.; Band, Guido P. H.; Stallen, Pieter Jan

2012-01-01

Through evaluative conditioning (EC) a stimulus can acquire an affective value by pairing it with another affective stimulus. While many sounds we encounter daily have acquired an affective value over life, EC has hardly been tested in the auditory domain. To get a more complete understanding of affective processing in auditory domain we examined EC of sound. In Experiment 1 we investigated whether the affective evaluation of short environmental sounds can be changed using affective words as unconditioned stimuli (US). Congruency effects on an affective priming task for conditioned sounds demonstrated successful EC. Subjective ratings for sounds paired with negative words changed accordingly. In Experiment 2 we investigated whether extinction occurs, i.e., whether the acquired valence remains stable after repeated presentation of the conditioned sound without the US. The acquired affective value remained present, albeit weaker, even after 40 extinction trials. These results provide clear evidence for EC effects in the auditory domain. We will argue that both associative as well as propositional processes are likely to underlie these effects. PMID:22514545

Social Factors in Aesthetics: Social Conformity Pressure and a Sense of Being Watched Affect Aesthetic Judgments

PubMed Central

Carbon, Claus-Christian; Hecht, Heiko

2017-01-01

The present study is a first attempt to experimentally test the impact of two specific social factors, namely social conformity pressure and a sense of being watched, on participants’ judgments of the artistic quality of aesthetic objects. We manipulated conformity pressure with a test form in which a photograph of each stimulus was presented together with unanimously low (downward pressure) or high quality ratings (upward pressure) of three would-be previous raters. Participants’ sense of being watched was manipulated by testing each of them in two settings, one of which contained an eyespots stimulus. Both social factors significantly affected the participants’ judgments—unexpectedly, however, with conformity pressure only working in the downward direction and eyespots leading to an overall downward shift in participants’ judgments. Our findings indicate the relevance of including explicit and implicit social factors in aesthetics research, thus also reminding us of the limitations of overly reductionist approaches to investigating aesthetic perception and experience. PMID:29201336

Social Factors in Aesthetics: Social Conformity Pressure and a Sense of Being Watched Affect Aesthetic Judgments.

PubMed

Hesslinger, Vera M; Carbon, Claus-Christian; Hecht, Heiko

2017-01-01

The present study is a first attempt to experimentally test the impact of two specific social factors, namely social conformity pressure and a sense of being watched, on participants' judgments of the artistic quality of aesthetic objects. We manipulated conformity pressure with a test form in which a photograph of each stimulus was presented together with unanimously low (downward pressure) or high quality ratings (upward pressure) of three would-be previous raters. Participants' sense of being watched was manipulated by testing each of them in two settings, one of which contained an eyespots stimulus. Both social factors significantly affected the participants' judgments-unexpectedly, however, with conformity pressure only working in the downward direction and eyespots leading to an overall downward shift in participants' judgments. Our findings indicate the relevance of including explicit and implicit social factors in aesthetics research, thus also reminding us of the limitations of overly reductionist approaches to investigating aesthetic perception and experience.

Effects of musical training on sound pattern processing in high-school students.

PubMed

Wang, Wenjung; Staffaroni, Laura; Reid, Errold; Steinschneider, Mitchell; Sussman, Elyse

2009-05-01

Recognizing melody in music involves detection of both the pitch intervals and the silence between sequentially presented sounds. This study tested the hypothesis that active musical training in adolescents facilitates the ability to passively detect sequential sound patterns compared to musically non-trained age-matched peers. Twenty adolescents, aged 15-18 years, were divided into groups according to their musical training and current experience. A fixed order tone pattern was presented at various stimulus rates while electroencephalogram was recorded. The influence of musical training on passive auditory processing of the sound patterns was assessed using components of event-related brain potentials (ERPs). The mismatch negativity (MMN) ERP component was elicited in different stimulus onset asynchrony (SOA) conditions in non-musicians than musicians, indicating that musically active adolescents were able to detect sound patterns across longer time intervals than age-matched peers. Musical training facilitates detection of auditory patterns, allowing the ability to automatically recognize sequential sound patterns over longer time periods than non-musical counterparts.

Does overall reinforcer rate affect discrimination of time-based contingencies?

PubMed

Cowie, Sarah; Davison, Michael; Blumhardt, Luca; Elliffe, Douglas

2016-05-01

Overall reinforcer rate appears to affect choice. The mechanism for such an effect is uncertain, but may relate to reinforcer rate changing the discrimination of the relation between stimuli and reinforcers. We assessed whether a quantitative model based on a stimulus-control approach could be used to account for the effects of overall reinforcer rate on choice under changing time-based contingencies. On a two-key concurrent schedule, the likely availability of a reinforcer reversed when a fixed time had elapsed since the last reinforcer, and the overall reinforcer rate was varied across conditions. Changes in the overall reinforcer rate produced a change in response bias, and some indication of a change in discrimination. These changes in bias and discrimination always occurred quickly, usually within the first session of a condition. The stimulus-control approach provided an excellent account of the data, suggesting that changes in overall reinforcer rate affect choice because they alter the frequency of reinforcers obtained at different times, or in different stimulus contexts, and thus change the discriminated relation between stimuli and reinforcers. These findings support the notion that temporal and spatial discriminations can be understood in terms of discrimination of reinforcers across time and space. © 2016 Society for the Experimental Analysis of Behavior.

Sex and the stimulus-movement effect: Differences in acquisition of autoshaped responding in cynomolgus monkeys.

PubMed

Rice, Nathaniel C; Makar, Jennifer R; Myers, Todd M

2017-03-15

The stimulus-movement effect refers to the phenomenon in which stimulus discrimination or acquisition of a response is facilitated by moving stimuli as opposed to stationary stimuli. The effect has been found in monkeys, rats, and humans, but the experiments conducted did not provide adequate female representation to investigate potential sex differences. The current experiment analyzed acquisition of stimulus touching in a progressive series of classical conditioning procedures in cynomolgus monkeys (Macaca fascicularis) as a function of sex and stimulus movement. Classical conditioning tasks arrange two or more stimuli in relation to each other with different temporal and predictive relations. Autoshaping procedures overlay operant contingencies onto a classical-conditioning stimulus arrangement. In the present case, a neutral stimulus (a small gray square displayed on a touchscreen) functioned as the conditional stimulus and a food pellet functioned as the unconditional stimulus. Although touching is not required to produce food, with repeated stimulus pairings subjects eventually touch the stimulus. Across conditions of increasing stimulus correlation and temporal contiguity, male monkeys acquired the response faster with a moving stimulus. In contrast, females acquired the response faster with a stationary stimulus. These results demonstrate that the stimulus-movement effect may be differentially affected by sex and indicate that additional experiments with females are needed to determine how sex interacts with behavioral phenomena discovered and elaborated almost exclusively using males. Published by Elsevier Inc.

Monkeys rely on recency of stimulus repetition when solving short-term memory tasks.

PubMed

Wittig, John H; Richmond, Barry J

2014-05-16

Seven monkeys performed variants of two short-term memory tasks that others have used to differentiate between selective and nonselective memory mechanisms. The first task was to view a list of sequentially presented images and identify whether a test matched any image from the list, but not a distractor from a preceding list. Performance was best when the test matched the most recently presented image. Response rates depended linearly on recency of repetition whether the test matched a sample from the current list or a distractor from a preceding list, suggesting nonselective memorization of all images viewed instead of just the sample images. The second task was to remember just the first image in a list selectively and ignore subsequent distractors. False alarms occurred frequently when the test matched a distractor presented near the beginning of the sequence. In a pilot experiment, response rates depended linearly on recency of repetition irrespective of whether the test matched the first image or a distractor, again suggesting nonselective memorization of all images instead of just the first image. Modification of the second task improved recognition of the first image, but did not abolish use of recency. Monkeys appear to perform nonspatial visual short-term memory tasks often (or exclusively) using a single, nonselective, memory mechanism that conveys the recency of stimulus repetition. Published by Cold Spring Harbor Laboratory Press.

Gestalt factors modulate basic spatial vision.

PubMed

Sayim, B; Westheimer, G; Herzog, M H

2010-05-01

Human perception of a stimulus varies depending on the context in which the stimulus is presented. Such contextual modulation has often been explained by two basic neural mechanisms: lateral inhibition and spatial pooling. In the present study, we presented observers with a vernier stimulus flanked by single lines; observers' ability to discriminate the offset direction of the vernier stimulus deteriorated in accordance with both explanations. However, when the flanking lines were part of a geometric shape (i.e., a good Gestalt), this deterioration strongly diminished. These findings cannot be explained by lateral inhibition or spatial pooling. It seems that Gestalt factors play an important role in contextual modulation. We propose that contextual modulation can be used as a quantitative measure to investigate the rules governing the grouping of elements into meaningful wholes.

Total Control – Pollen Presentation and Floral Longevity in Loasaceae (Blazing Star Family) Are Modulated by Light, Temperature and Pollinator Visitation Rates

PubMed Central

Henning, Tilo; Weigend, Maximilian

2012-01-01

Stamen movements can be understood as a mechanism influencing pollen presentation and increasing outbreeding success of hermaphroditic flowers via optimized male function. In this study we experimentally analyzed the factors regulating autonomous and thigmonastic (triggered by flower visitors) stamen movements in eight species of Loasaceae. Both types of stamen movements are positively influenced by light and temperature and come to a virtual standstill in the dark and at low temperatures (12°C). Pollen presentation is thus discontinued during periods where pollinators are not active. Overall stamen presentation increases with increasing flower age. Contrary to expectation, no geometrical correlation between the floral scale stimulated and the stamen fascicle reacting exists, indicating that the stimulus is transmitted over the receptacle and stamen maturation dictates which and how many stamens react. Thigmonastic stamen presentation is dramatically accelerated compared to autonomous movement (3–37 times), indicating that the rate of stamen maturation can be adjusted to different visitation schedules. Flowers can react relatively uniformly down to stimulation intervals of 10–15 min., consistently presenting comparable numbers of stamens in the flower c. 5 min. after the stimulus and can thus keep the amount of pollen presented relatively constant even under very high visitation frequencies of 4–6 visits/h. Thigmonastic pollen presentation dramatically reduces the overall duration of the staminate phase (to 1/3rd in Nasa macrothyrsa). Similarly, the carpellate phase is dramatically reduced after pollination, down to 1 d from 4 d. Overall flower longevity is reduced by more than 2/3rds under high visitation rates (<3 d versus 10 d under visitor exclusion) and depleted and pollinated flowers are rapidly removed from the pool. Complex floral behaviour in Loasaceae thus permits a near-total control over pollen dispensation schedules and floral longevity of the individual flower by an extraordinary fine-tuning to both biotic and abiotic factors. PMID:22916102

Responses of juvenile bonnet macaques to social stimuli presented through color videotapes.

PubMed

Plimpton, E H; Swartz, K B; Rosenblum, L A

1981-03-01

Twelve juvenile bonnet macaques (Macaca radiata), 6 males and 6 females, were presented with color videotape recordings of 3 types of social stimuli. The stimulus animals, all unfamiliar adult conspecifics, consisted of a passive female, a passive male, and a threatening male. Subjects were observed in the presence of their mother and 1 other juvenile-mother dyad. The juveniles showed the highest scores for contact with mother when presented with the threatening male stimulus. Similarly, subjects lipsmacked significantly more to the male threatening male stimulus than to either the passive male or female. The female stimulus was approached significantly more than either the passive or threatening male. Results suggest that juvenile macaques will respond to social stimuli presented through color video recordings in a socially appropriate manner. This technique provides a new tool in the investigation of social perception in nonhuman primates.

Unconscious and conscious processing of negative emotions examined through affective priming.

PubMed

Okubo, Chisa; Ogawa, Toshiki

2013-04-01

This study investigated unconscious and conscious processes by which negative emotions arise. Participants (26 men, 47 women; M age = 20.3 yr.) evaluated target words that were primed with subliminally or supraliminally presented emotional pictures. Stimulus onset asynchrony was either 200 or 800 msec. With subliminal presentations, reaction times to negative targets were longer than reaction times to positive targets after negative primes for the 200-msec. stimulus onset asynchrony. Reaction times to positive targets after negative or positive primes were shorter when the stimulus onset asynchrony was 800 msec. For supraliminal presentations, reaction times were longer when evaluating targets that followed emotionally opposite primes. When emotional stimuli were consciously distinguished, the evoked emotional states might lead to emotional conflicts, although the qualitatively different effects might be caused when subliminally presented emotion evoking stimulus was appraised unconsciously; that possibility was discussed.

Sex-dependent modulation of ultrasonic vocalizations in house mice (Mus musculus musculus)

PubMed Central

Reitschmidt, Doris; Noll, Anton; Balazs, Peter; Penn, Dustin J.

2017-01-01

House mice (Mus musculus) emit ultrasonic vocalizations (USVs), which are surprisingly complex and have features of bird song, but their functions are not well understood. Previous studies have reported mixed evidence on whether there are sex differences in USV emission, though vocalization rate or other features may depend upon whether potential receivers are of the same or opposite sex. We recorded the USVs of wild-derived adult house mice (F1 of wild-caught Mus musculus musculus), and we compared the vocalizations of males and females in response to a stimulus mouse of the same- or opposite-sex. To detect and quantify vocalizations, we used an algorithm that automatically detects USVs (Automatic Mouse Ultrasound Detector or A-MUD). We found high individual variation in USV emission rates (4 to 2083 elements/10 min trial) and a skewed distribution, with most mice (60%) emitting few (≤50) elements. We found no differences in the rates of calling between the sexes overall, but mice of both sexes emitted vocalizations at a higher rate and higher frequencies during opposite- compared to same-sex interactions. We also observed a trend toward higher amplitudes by males when presented with a male compared to a female stimulus. Our results suggest that mice modulate the rate and frequency of vocalizations depending upon the sex of potential receivers. PMID:29236704

Do intensity ratings and skin conductance responses reliably discriminate between different stimulus intensities in experimentally induced pain?

PubMed

Breimhorst, Markus; Sandrock, Stephan; Fechir, Marcel; Hausenblas, Nadine; Geber, Christian; Birklein, Frank

2011-01-01

The present study addresses the question whether pain-intensity ratings and skin conductance responses (SCRs) are able to detect different intensities of phasic painful stimuli and to determine the reliability of this discrimination. For this purpose, 42 healthy participants of both genders were assigned to either electrical, mechanical, or laser heat-pain stimulation (each n = 14). A whole range of single brief painful stimuli were delivered on the right volar forearm of the dominant hand in a randomized order. Pain-intensity ratings and SCRs were analyzed. Using generalizability theory, individual and gender differences were the main contributors to the variability of both intensity ratings and SCRs. Most importantly, we showed that pain-intensity ratings are a reliable measure for the discrimination of different pain stimulus intensities in the applied modalities. The reliability of SCR was adequate when mechanical and heat stimuli were tested but failed for the discrimination of electrical stimuli. Further studies are needed to reveal the reason for this lack of accuracy for SCRs when applying electrical pain stimuli. Our study could help researchers to better understand the relationship between pain and activation of the sympathetic nervous system. Pain researchers are furthermore encouraged to consider individual and gender differences when measuring pain intensity and the concomitant SCRs in experimental settings. Copyright © 2011 American Pain Society. Published by Elsevier Inc. All rights reserved.

Normative behavioral thresholds for short tone-bursts.

PubMed

Beattie, R C; Rochverger, I

2001-10-01

Although tone-bursts have been commonly used in auditory brainstem response (ABR) evaluations for many years, national standards describing normal calibration values have not been established. This study was designed to gather normative threshold data to establish a physical reference for tone-burst stimuli that can be reproduced across clinics and laboratories. More specifically, we obtained norms for 3-msec tone-bursts presented at two repetition rates (9.3/sec and 39/sec), two gating functions (Trapezoid and Blackman), and four frequencies (500, 1000, 2000, and 4000 Hz). Our results are specified using three physical references: dB peak sound pressure level, dB peak-to-peak equivalent sound pressure level, and dB SPL (fast meter response, rate = 50 stimuli/sec). These data are offered for consideration when calibrating ABR equipment. The 39/sec stimulus rate yielded tone-burst thresholds that were approximately 3 dB lower than the 9.3/sec rate. The improvement in threshold with increasing stimulus rate may reflect the ability of the auditory system to integrate energy that occurs within a time interval of 200 to 500 msec (temporal integration). The Trapezoid gating function yielded thresholds that averaged 1.4 dB lower than the Blackman function. Although these differences are small and of little clinical importance, the cumulative effects of several instrument and/or procedural variables may yield clinically important differences.

Simultaneous odour-face presentation strengthens hedonic evaluations and event-related potential responses influenced by unpleasant odour.

PubMed

Cook, Stephanie; Kokmotou, Katerina; Soto, Vicente; Wright, Hazel; Fallon, Nicholas; Thomas, Anna; Giesbrecht, Timo; Field, Matt; Stancak, Andrej

2018-04-13

Odours alter evaluations of concurrently presented visual stimuli, such as faces. Stimulus onset asynchrony (SOA) is known to affect evaluative priming in various sensory modalities. However, effects of SOA on odour priming of visual stimuli are not known. The present study aimed to analyse whether subjective and cortical activation changes during odour priming would vary as a function of SOA between odours and faces. Twenty-eight participants rated faces under pleasant, unpleasant, and no-odour conditions using visual analogue scales. In half of trials, faces appeared one-second after odour offset (SOA 1). In the other half of trials, faces appeared during the odour pulse (SOA 2). EEG was recorded continuously using a 128-channel system, and event-related potentials (ERPs) to face stimuli were evaluated using statistical parametric mapping (SPM). Faces presented during unpleasant-odour stimulation were rated significantly less pleasant than the same faces presented one-second after offset of the unpleasant odour. Scalp-time clusters in the late-positive-potential (LPP) time-range showed an interaction between odour and SOA effects, whereby activation was stronger for faces presented simultaneously with the unpleasant odour, compared to the same faces presented after odour offset. Our results highlight stronger unpleasant odour priming with simultaneous, compared to delayed, odour-face presentation. Such effects were represented in both behavioural and neural data. A greater cortical and subjective response during simultaneous presentation of faces and unpleasant odour may have an adaptive role, allowing for a prompt and focused behavioural reaction to a concurrent stimulus if an aversive odour would signal danger, or unwanted social interaction. Copyright © 2018 Elsevier B.V. All rights reserved.

Effect of stimulus type and temperature on EEG reactivity in cardiac arrest.

PubMed

Fantaneanu, Tadeu A; Tolchin, Benjamin; Alvarez, Vincent; Friolet, Raymond; Avery, Kathleen; Scirica, Benjamin M; O'Brien, Molly; Henderson, Galen V; Lee, Jong Woo

2016-11-01

Electroencephalogram (EEG) background reactivity is a reliable outcome predictor in cardiac arrest patients post therapeutic hypothermia. However, there is no consensus on modality testing and prior studies reveal only fair to moderate agreement rates. The aim of this study was to explore different stimulus modalities and report interrater agreements. We studied a multicenter, prospectively collected cohort of cardiac arrest patients who underwent therapeutic hypothermia between September 2014 and December 2015. We identified patients with reactivity data and evaluated interrater agreements of different stimulus modalities tested in hypothermia and normothermia. Of the 60 patients studied, agreement rates were moderate to substantial during hypothermia and fair to moderate during normothermia. Bilateral nipple pressure is more sensitive (80%) when compared to other modalities in eliciting a reactive background in hypothermia. Auditory, nasal tickle, nailbed pressure and nipple pressure reactivity were associated with good outcomes in both hypothermia and normothermia. EEG reactivity varies depending on the stimulus testing modality as well as the temperature during which stimulation is performed, with nipple pressure emerging as the most sensitive during hypothermia for reactivity and outcome determination. This highlights the importance of multiple stimulus testing modalities in EEG reactivity determination to reduce false negatives and optimize prognostication. Copyright © 2016 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

A user-friendly SSVEP-based brain-computer interface using a time-domain classifier.

PubMed

Luo, An; Sullivan, Thomas J

2010-04-01

We introduce a user-friendly steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) system. Single-channel EEG is recorded using a low-noise dry electrode. Compared to traditional gel-based multi-sensor EEG systems, a dry sensor proves to be more convenient, comfortable and cost effective. A hardware system was built that displays four LED light panels flashing at different frequencies and synchronizes with EEG acquisition. The visual stimuli have been carefully designed such that potential risk to photosensitive people is minimized. We describe a novel stimulus-locked inter-trace correlation (SLIC) method for SSVEP classification using EEG time-locked to stimulus onsets. We studied how the performance of the algorithm is affected by different selection of parameters. Using the SLIC method, the average light detection rate is 75.8% with very low error rates (an 8.4% false positive rate and a 1.3% misclassification rate). Compared to a traditional frequency-domain-based method, the SLIC method is more robust (resulting in less annoyance to the users) and is also suitable for irregular stimulus patterns.

Preserving information in neural transmission.

PubMed

Sincich, Lawrence C; Horton, Jonathan C; Sharpee, Tatyana O

2009-05-13

Along most neural pathways, the spike trains transmitted from one neuron to the next are altered. In the process, neurons can either achieve a more efficient stimulus representation, or extract some biologically important stimulus parameter, or succeed at both. We recorded the inputs from single retinal ganglion cells and the outputs from connected lateral geniculate neurons in the macaque to examine how visual signals are relayed from retina to cortex. We found that geniculate neurons re-encoded multiple temporal stimulus features to yield output spikes that carried more information about stimuli than was available in each input spike. The coding transformation of some relay neurons occurred with no decrement in information rate, despite output spike rates that averaged half the input spike rates. This preservation of transmitted information was achieved by the short-term summation of inputs that geniculate neurons require to spike. A reduced model of the retinal and geniculate visual responses, based on two stimulus features and their associated nonlinearities, could account for >85% of the total information available in the spike trains and the preserved information transmission. These results apply to neurons operating on a single time-varying input, suggesting that synaptic temporal integration can alter the temporal receptive field properties to create a more efficient representation of visual signals in the thalamus than the retina.

Attentional bias to pain and social threat in pediatric patients with functional abdominal pain and pain-free youth before and after performance evaluation.

PubMed

Beck, Joy E; Lipani, Tricia A; Baber, Kari F; Dufton, Lynette; Garber, Judy; Smith, Craig A; Walker, Lynn S

2011-05-01

This study investigated attentional biases for pain and social threat versus neutral stimuli in 54 youth with functional abdominal pain (FAP) and 53 healthy control subjects (ages 10 to 16 years). We assessed attentional bias using a visual probe detection task (PDT) that presented pain and social threat words in comparison to neutral words at conscious (1250 ms) and preconscious (20 ms) presentation rates. We administered the PDT before and after random assignment of participants to a laboratory stressor--failure versus success feedback regarding their performance on a challenging computer game. All analyses controlled for trait anxiety. At the conscious rate of stimulus presentation, FAP patients exhibited preferential attention toward pain compared with neutral stimuli and compared with the control group. FAP patients maintained preferential attention toward conscious pain stimuli after performance feedback in both failure and success conditions. At the preconscious rate of stimulus presentation, FAP patients' attention was neutral at baseline but increased significantly toward pain stimuli after performance feedback in both failure and success conditions. FAP patients' somatic symptoms increased in both failure and success conditions; control youth's somatic symptoms only increased after failure. Regarding social threat, neither FAP nor control youth exhibited attentional bias toward social threat compared with neutral stimuli at baseline, but both FAP and control youth in the failure condition significantly increased attention away from social threat after failure feedback. Results suggest that FAP patients preferentially attend to pain stimuli in conscious awareness. Moreover, performance evaluation may activate their preconscious attention to pain stimuli. Copyright © 2011 International Association for the Study of Pain. Published by Elsevier B.V. All rights reserved.

Enhanced conditioned eyeblink response acquisition and proactive interference in anxiety vulnerable individuals

PubMed Central

Holloway, Jacqueline L.; Trivedi, Payal; Myers, Catherine E.; Servatius, Richard J.

2012-01-01

In classical conditioning, proactive interference may arise from experience with the conditioned stimulus (CS), the unconditional stimulus (US), or both, prior to their paired presentations. Interest in the application of proactive interference has extended to clinical populations as either a risk factor for disorders or as a secondary sign. Although the current literature is dense with comparisons of stimulus pre-exposure effects in animals, such comparisons are lacking in human subjects. As such, interpretation of proactive interference over studies as well as its generalization and utility in clinical research is limited. The present study was designed to assess eyeblink response acquisition after equal numbers of CS, US, and explicitly unpaired CS and US pre-exposures, as well as to evaluate how anxiety vulnerability might modulate proactive interference. In the current study, anxiety vulnerability was assessed using the State/Trait Anxiety Inventories as well as the adult and retrospective measures of behavioral inhibition (AMBI and RMBI, respectively). Participants were exposed to 1 of 4 possible pre-exposure contingencies: 30 CS, 30 US, 30 CS, and 30 US explicitly unpaired pre-exposures, or Context pre-exposure, immediately prior to standard delay training. Robust proactive interference was evident in all pre-exposure groups relative to Context pre-exposure, independent of anxiety classification, with CR acquisition attenuated at similar rates. In addition, trait anxious individuals were found to have enhanced overall acquisition as well as greater proactive interference relative to non-vulnerable individuals. The findings suggest that anxiety vulnerable individuals learn implicit associations faster, an effect which persists after the introduction of new stimulus contingencies. This effect is not due to enhanced sensitivity to the US. Such differences would have implications for the development of anxiety psychopathology within a learning framework. PMID:23162449

Enhanced conditioned eyeblink response acquisition and proactive interference in anxiety vulnerable individuals.

PubMed

Holloway, Jacqueline L; Trivedi, Payal; Myers, Catherine E; Servatius, Richard J

2012-01-01

In classical conditioning, proactive interference may arise from experience with the conditioned stimulus (CS), the unconditional stimulus (US), or both, prior to their paired presentations. Interest in the application of proactive interference has extended to clinical populations as either a risk factor for disorders or as a secondary sign. Although the current literature is dense with comparisons of stimulus pre-exposure effects in animals, such comparisons are lacking in human subjects. As such, interpretation of proactive interference over studies as well as its generalization and utility in clinical research is limited. The present study was designed to assess eyeblink response acquisition after equal numbers of CS, US, and explicitly unpaired CS and US pre-exposures, as well as to evaluate how anxiety vulnerability might modulate proactive interference. In the current study, anxiety vulnerability was assessed using the State/Trait Anxiety Inventories as well as the adult and retrospective measures of behavioral inhibition (AMBI and RMBI, respectively). Participants were exposed to 1 of 4 possible pre-exposure contingencies: 30 CS, 30 US, 30 CS, and 30 US explicitly unpaired pre-exposures, or Context pre-exposure, immediately prior to standard delay training. Robust proactive interference was evident in all pre-exposure groups relative to Context pre-exposure, independent of anxiety classification, with CR acquisition attenuated at similar rates. In addition, trait anxious individuals were found to have enhanced overall acquisition as well as greater proactive interference relative to non-vulnerable individuals. The findings suggest that anxiety vulnerable individuals learn implicit associations faster, an effect which persists after the introduction of new stimulus contingencies. This effect is not due to enhanced sensitivity to the US. Such differences would have implications for the development of anxiety psychopathology within a learning framework.

The Mere Exposure Instruction Effect.

PubMed

Van Dessel, Pieter; Mertens, Gaëtan; Smith, Colin Tucker; De Houwer, Jan

2017-09-01

The mere exposure effect refers to the well-established finding that people evaluate a stimulus more positively after repeated exposure to that stimulus. We investigated whether a change in stimulus evaluation can occur also when participants are not repeatedly exposed to a stimulus, but are merely instructed that one stimulus will occur frequently and another stimulus will occur infrequently. We report seven experiments showing that (1) mere exposure instructions influence implicit stimulus evaluations as measured with an Implicit Association Test (IAT), personalized Implicit Association Test (pIAT), or Affect Misattribution Procedure (AMP), but not with an Evaluative Priming Task (EPT), (2) mere exposure instructions influence explicit evaluations, and (3) the instruction effect depends on participants' memory of which stimulus will be presented more frequently. We discuss how these findings inform us about the boundary conditions of mere exposure instruction effects, as well as the mental processes that underlie mere exposure and mere exposure instruction effects.

Simultaneous perceptual and response biases on sequential face attractiveness judgments.

PubMed

Pegors, Teresa K; Mattar, Marcelo G; Bryan, Peter B; Epstein, Russell A

2015-06-01

Face attractiveness is a social characteristic that we often use to make first-pass judgments about the people around us. However, these judgments are highly influenced by our surrounding social world, and researchers still understand little about the mechanisms underlying these influences. In a series of 3 experiments, we use a novel sequential rating paradigm that enables us to measure biases in attractiveness judgments from the previous face and the previous rating. Our results reveal 2 simultaneous and opposing influences on face attractiveness judgments that arise from past experience of faces: a response bias in which attractiveness ratings shift toward a previously given rating and a stimulus bias in which attractiveness ratings shift away from the mean attractiveness of the previous face. Further, we provide evidence that the contrastive stimulus bias (but not the assimilative response bias) is strengthened by increasing the duration of the previous stimulus, suggesting an underlying perceptual mechanism. These results demonstrate that judgments of face attractiveness are influenced by information from our evaluative and perceptual history and that these influences have measurable behavioral effects over the course of just a few seconds. (c) 2015 APA, all rights reserved).

Stimulus Overselectivity: Empirical Basis and Diagnostic Methods

ERIC Educational Resources Information Center

Cipani, Ennio

2012-01-01

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…

Central Cannabinoid Receptors Modulate Acquisition of Eyeblink Conditioning

ERIC Educational Resources Information Center

Steinmetz, Adam B.; Freeman, John H.

2010-01-01

Delay eyeblink conditioning is established by paired presentations of a conditioned stimulus (CS) such as a tone or light, and an unconditioned stimulus (US) that elicits the blink reflex. Conditioned stimulus information is projected from the basilar pontine nuclei to the cerebellar interpositus nucleus and cortex. The cerebellar cortex,…

Responding for sucrose and wheel-running reinforcement: effect of body weight manipulation.

PubMed

Belke, Terry W

2004-02-27

As body weight increases, the excitatory strength of a stimulus signaling an opportunity to run should weaken to a greater degree than that of a stimulus signaling an opportunity to eat. To test this hypothesis, six male albino Wistar rats were placed in running wheels and exposed to a fixed interval 30-s schedule that produced either a drop of 15% sucrose solution or the opportunity to run for 15s as reinforcing consequences for lever pressing. Each reinforcer type was signaled by a different stimulus. The effect of varying body weight on responding maintained by these two reinforcers was investigated by systematically increasing and decreasing post-session food amounts. The initial body weight was 335 g. Body weights were increased to approximately 445 g and subsequently returned to 335 g. As body weight increased, overall and local lever-pressing rates decreased while post-reinforcement pauses lengthened. Analysis of post-reinforcement pauses and local lever-pressing rates in terms of transitions between successive reinforcers revealed that local response rates in the presence of stimuli signaling upcoming wheel and sucrose reinforcers were similarly affected. However, pausing in the presence of the stimulus signaling a wheel-running reinforcer lengthened to a greater extent than did pausing in the presence of the stimulus signaling sucrose. This result suggests that as body weight approaches ad-lib levels, the likelihood of initiation of responding to obtain an opportunity to run approaches zero and the animal "rejects" the opportunity to run in a manner similar to the rejection of less preferred food items in studies of food selectivity.

Perception of trigeminal mixtures.

PubMed

Filiou, Renée-Pier; Lepore, Franco; Bryant, Bruce; Lundström, Johan N; Frasnelli, Johannes

2015-01-01

The trigeminal system is a chemical sense allowing for the perception of chemosensory information in our environment. However, contrary to smell and taste, we lack a thorough understanding of the trigeminal processing of mixtures. We, therefore, investigated trigeminal perception using mixtures of 3 relatively receptor-specific agonists together with one control odor in different proportions to determine basic perceptual dimensions of trigeminal perception. We found that 4 main dimensions were linked to trigeminal perception: sensations of intensity, warmth, coldness, and pain. We subsequently investigated perception of binary mixtures of trigeminal stimuli by means of these 4 perceptual dimensions using different concentrations of a cooling stimulus (eucalyptol) mixed with a stimulus that evokes warmth perception (cinnamaldehyde). To determine if sensory interactions are mainly of central or peripheral origin, we presented stimuli in a physical "mixture" or as a "combination" presented separately to individual nostrils. Results showed that mixtures generally yielded higher ratings than combinations on the trigeminal dimensions "intensity," "warm," and "painful," whereas combinations yielded higher ratings than mixtures on the trigeminal dimension "cold." These results suggest dimension-specific interactions in the perception of trigeminal mixtures, which may be explained by particular interactions that may take place on peripheral or central levels. © The Author 2014. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The inferior colliculus encodes the Franssen auditory spatial illusion

PubMed Central

Rajala, Abigail Z.; Yan, Yonghe; Dent, Micheal L.; Populin, Luis C.

2014-01-01

Illusions are effective tools for the study of the neural mechanisms underlying perception because neural responses can be correlated to the physical properties of stimuli and the subject’s perceptions. The Franssen illusion (FI) is an auditory spatial illusion evoked by presenting a transient, abrupt tone and a slowly rising, sustained tone of the same frequency simultaneously on opposite sides of the subject. Perception of the FI consists of hearing a single sound, the sustained tone, on the side that the transient was presented. Both subcortical and cortical mechanisms for the FI have been proposed, but, to date, there is no direct evidence for either. The data show that humans and rhesus monkeys perceive the FI similarly. Recordings were taken from single units of the inferior colliculus in the monkey while they indicated the perceived location of sound sources with their gaze. The results show that the transient component of the Franssen stimulus, with a shorter first spike latency and higher discharge rate than the sustained tone, encodes the perception of sound location. Furthermore, the persistent erroneous perception of the sustained stimulus location is due to continued excitation of the same neurons, first activated by the transient, by the sustained stimulus without location information. These results demonstrate for the first time, on a trial-by-trial basis, a correlation between perception of an auditory spatial illusion and a subcortical physiological substrate. PMID:23899307

Does attention speed up processing? Decreases and increases of processing rates in visual prior entry.

PubMed

Tünnermann, Jan; Petersen, Anders; Scharlau, Ingrid

2015-03-02

Selective visual attention improves performance in many tasks. Among others, it leads to "prior entry"--earlier perception of an attended compared to an unattended stimulus. Whether this phenomenon is purely based on an increase of the processing rate of the attended stimulus or if a decrease in the processing rate of the unattended stimulus also contributes to the effect is, up to now, unanswered. Here we describe a novel approach to this question based on Bundesen's Theory of Visual Attention, which we use to overcome the limitations of earlier prior-entry assessment with temporal order judgments (TOJs) that only allow relative statements regarding the processing speed of attended and unattended stimuli. Prevalent models of prior entry in TOJs either indirectly predict a pure acceleration or cannot model the difference between acceleration and deceleration. In a paradigm that combines a letter-identification task with TOJs, we show that indeed acceleration of the attended and deceleration of the unattended stimuli conjointly cause prior entry. © 2015 ARVO.

Probability effects on stimulus evaluation and response processes

NASA Technical Reports Server (NTRS)

Gehring, W. J.; Gratton, G.; Coles, M. G.; Donchin, E.

1992-01-01

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.

Instruction-Based Approach-Avoidance Effects: Changing Stimulus Evaluation via the Mere Instruction to Approach or Avoid Stimuli.

PubMed

Van Dessel, Pieter; De Houwer, Jan; Gast, Anne; Tucker Smith, Colin

2015-01-01

Prior research suggests that repeatedly approaching or avoiding a certain stimulus changes the liking of this stimulus. We investigated whether these effects of approach and avoidance training occur also when participants do not perform these actions but are merely instructed about the stimulus-action contingencies. Stimulus evaluations were registered using both implicit (Implicit Association Test and evaluative priming) and explicit measures (valence ratings). Instruction-based approach-avoidance effects were observed for relatively neutral fictitious social groups (i.e., Niffites and Luupites), but not for clearly valenced well-known social groups (i.e., Blacks and Whites). We conclude that instructions to approach or avoid stimuli can provide sufficient bases for establishing both implicit and explicit evaluations of novel stimuli and discuss several possible reasons for why similar instruction-based approach-avoidance effects were not found for valenced well-known stimuli.

Prestimulus EEG Power Predicts Conscious Awareness But Not Objective Visual Performance

PubMed Central

Veniero, Domenica

2017-01-01

Abstract Prestimulus oscillatory neural activity has been linked to perceptual outcomes during performance of psychophysical detection and discrimination tasks. Specifically, the power and phase of low frequency oscillations have been found to predict whether an upcoming weak visual target will be detected or not. However, the mechanisms by which baseline oscillatory activity influences perception remain unclear. Recent studies suggest that the frequently reported negative relationship between α power and stimulus detection may be explained by changes in detection criterion (i.e., increased target present responses regardless of whether the target was present/absent) driven by the state of neural excitability, rather than changes in visual sensitivity (i.e., more veridical percepts). Here, we recorded EEG while human participants performed a luminance discrimination task on perithreshold stimuli in combination with single-trial ratings of perceptual awareness. Our aim was to investigate whether the power and/or phase of prestimulus oscillatory activity predict discrimination accuracy and/or perceptual awareness on a trial-by-trial basis. Prestimulus power (3–28 Hz) was inversely related to perceptual awareness ratings (i.e., higher ratings in states of low prestimulus power/high excitability) but did not predict discrimination accuracy. In contrast, prestimulus oscillatory phase did not predict awareness ratings or accuracy in any frequency band. These results provide evidence that prestimulus α power influences the level of subjective awareness of threshold visual stimuli but does not influence visual sensitivity when a decision has to be made regarding stimulus features. Hence, we find a clear dissociation between the influence of ongoing neural activity on conscious awareness and objective performance. PMID:29255794

Complementary modulation of N2 and CRN by conflict frequency.

PubMed

Grützmann, Rosa; Riesel, Anja; Klawohn, Julia; Kathmann, Norbert; Endrass, Tanja

2014-08-01

The present study investigated the modulation of the N2 and the correct-related negativity (CRN) by conflict frequency. Conflict costs, as measured by reaction times and error rate, were reduced with increasing conflict frequency, indicating improved conflict resolution. N2 amplitudes in incompatible trials increased with higher conflict frequency, while postresponse CRN amplitudes decreased. In concert with behavioral findings of reduced conflict costs and greater interference suppression, the increase of N2 might reflect enhanced conflict resolution during stimulus processing. The CRN, however, might reflect postresponse implementation of cognitive control, which is reduced when conflict is already adequately resolved during stimulus processing. Furthermore, N2 and CRN in incompatible trials were inversely related on the between- and within-subject level, implying that the two modes of implementing cognitive control are applied complementarily. Copyright © 2014 Society for Psychophysiological Research.

When Self-Descriptions Contradict Behavior: Actions Do Speak Louder Than Words.

ERIC Educational Resources Information Center

Amabile, Teresa M.; Kabat, Loren G.

To examine whether a person's actions are more important in determining impressions of personality than are self-descriptions, subjects in two separate studies viewed two videotapes, one depicting a stimulus person's self-description and the other depicting that person's behavior in a conversation. Subjects rated the stimulus person on several…

Age and automation interact to influence performance of a simulated luggage screening task.

PubMed

Wiegmann, Douglas; McCarley, Jason S; Kramer, Arthur F; Wickens, Christopher D

2006-08-01

An experiment examined the impact of automation on young and old adults' abilities to detect threat objects in a simulated baggage-screening task. Younger and older adult participants viewed X-ray images of cluttered baggage, 20% of which contained a hidden knife. Some participants were provided an automated aid with a hit rate of 0.90 and a false alarm rate of 0.25. The aid provided assistance to participants in one of three forms: a text message that appeared before the stimulus image; a text message that appeared following the stimulus image; or a spatial cue concurrent with the stimulus image. Control participants performed the task with no assistance from an aid. Spatial cuing improved performance for both age groups. Text cuing improved young adults' performance, but had no benefit for older participants. Effects were similar whether the text cue preceded or followed the search stimulus itself. Results indicate that spatial cuing rather than text alerts may be more effective in aiding performance during a baggage screening task and such benefits are likely to occur regardless of operator age.

Pain sensation during cold stimulation of the teeth: differential reflection of A delta and C fibre activity?

PubMed

Mengel, M K; Stiefenhofer, A E; Jyväsjärvi, E; Kniffki, K D

1993-11-01

Cold stimuli of varying intensities were randomly applied to upper middle incisors of 12 healthy young subjects for a mean duration of 2 min by individually adapted thermodes the temperatures of which ranged from +30 degrees C to -30 degrees C. The subjects were asked to rate the magnitude of their pain sensations during application of the stimuli by means of a linear potentiometer according to a category scale. After each stimulus, they were asked to describe the quality of their pain sensations. Cold stimulation of the teeth evoked pain sensations were reproducible that in subsequent trials and could be graded according to stimulation intensity. Below certain individually different threshold thermode temperatures the onset of a stimulus was followed, after a short latency (1.6 +/- 1 sec), by a sharp and shooting pain sensation which immediately decreased after reaching its maximum value while the stimulus was still present. The mean maxima of the pain intensities were correlated to the thermode temperature. In general, this first pain component was followed by a second one (latency: 29.9 +/- 6.3 sec) with a lower threshold temperature, less of an increase in rate and lower magnitude. This was described as a dull, burning pain which was difficult to localize. The human pain ratings are compared to recordings of intradental nerve fibres in the cat and, under the assumption that the response behaviour of human pulpal nerve fibres is comparable to that of the cat, we hypothesize that the first pain component is evoked by intradental A delta fibres exhibiting their typical phasic response behaviour and firing during the initial steep temperature decrease. After some seconds, intradental temperature reached values sufficient to evoke C-fibre activity associated with the second pain component.

Accounting for rate-dependent category boundary shifts in speech perception.

PubMed

Bosker, Hans Rutger

2017-01-01

The perception of temporal contrasts in speech is known to be influenced by the speech rate in the surrounding context. This rate-dependent perception is suggested to involve general auditory processes because it is also elicited by nonspeech contexts, such as pure tone sequences. Two general auditory mechanisms have been proposed to underlie rate-dependent perception: durational contrast and neural entrainment. This study compares the predictions of these two accounts of rate-dependent speech perception by means of four experiments, in which participants heard tone sequences followed by Dutch target words ambiguous between /ɑs/ "ash" and /a:s/ "bait". Tone sequences varied in the duration of tones (short vs. long) and in the presentation rate of the tones (fast vs. slow). Results show that the duration of preceding tones did not influence target perception in any of the experiments, thus challenging durational contrast as explanatory mechanism behind rate-dependent perception. Instead, the presentation rate consistently elicited a category boundary shift, with faster presentation rates inducing more /a:s/ responses, but only if the tone sequence was isochronous. Therefore, this study proposes an alternative, neurobiologically plausible account of rate-dependent perception involving neural entrainment of endogenous oscillations to the rate of a rhythmic stimulus.

Perceptual load modifies processing of unattended stimuli both in the presence and absence of attended stimuli.

PubMed

Couperus, J W

2010-11-26

This study explored effects of perceptual load on stimulus processing in the presence and absence of an attended stimulus. Participants were presented with a bilateral or unilateral display and asked to perform a discrimination task at either low or high perceptual load. Electrophysiological responses to stimuli were then compared at the P100 and N100. As in previous studies, perceptual load modified processing of attended and unattended stimuli seen at occipital scalp sites. Moreover, perceptual load modulated attention effects when the attended stimulus was presented at high perceptual load for unilateral displays. However, this was not true when the attended and unattended stimulus appeared simultaneously in bilateral displays. Instead, only a main effect of perceptual load was found. Reductions in processing contralateral to the unattended stimulus at the N100 provide support for Lavie's (1995) theory of selective attention. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Unconscious semantic activation depends on feature-specific attention allocation.

PubMed

Spruyt, Adriaan; De Houwer, Jan; Everaert, Tom; Hermans, Dirk

2012-01-01

We examined whether semantic activation by subliminally presented stimuli is dependent upon the extent to which participants assign attention to specific semantic stimulus features and stimulus dimensions. Participants pronounced visible target words that were preceded by briefly presented, masked prime words. Both affective and non-affective semantic congruence of the prime-target pairs were manipulated under conditions that either promoted selective attention for affective stimulus information or selective attention for non-affective semantic stimulus information. In line with our predictions, results showed that affective congruence had a clear impact on word pronunciation latencies only if participants were encouraged to assign attention to the affective stimulus dimension. In contrast, non-affective semantic relatedness of the prime-target pairs produced no priming at all. Our findings are consistent with the hypothesis that unconscious activation of (affective) semantic information is modulated by feature-specific attention allocation. Copyright © 2011 Elsevier B.V. All rights reserved.

The moderating effect of stimulus attractiveness on the effect of alcohol consumption on attractiveness ratings.

PubMed

Chen, Xiong; Wang, Xiaoyu; Yang, Dong; Chen, Youguo

2014-01-01

To explore the enhancing effect of alcohol consumption on attractiveness ratings, in that few studies on the Beer Goggles effect control the stimuli attractiveness level and researchers have seldom considered extending the effect to stimuli other than faces. Male and female participants (n = 103) were randomly assigned to alcohol consumption or placebo groups. Both groups were asked to assess the attractiveness of two types of pictures (faces and landscapes) with three levels of attractiveness for each stimulus category (high, moderate and low). We found significant interactions between beverage type and attractiveness level. Attractiveness ratings for moderate- and low-attractiveness faces were significantly higher in the alcohol compared with placebo condition, while there was no significant difference for high-attractiveness stimuli between these two conditions. As for landscapes, only low-attractiveness stimuli were rated significantly higher in the alcohol condition. Whether or not alcohol consumption leads to an increase in attractiveness ratings depends on the initial attractiveness of the stimulus materials. Alcohol consumption tends to affect ratings for stimuli with relatively low attractiveness. Furthermore, this effect is not limited to faces; it extends to other types of stimuli like landscapes. © The Author 2014. Medical Council on Alcohol and Oxford University Press. All rights reserved.

Detection Rates of Cortical Auditory Evoked Potentials at Different Sensation Levels in Infants with Sensory/Neural Hearing Loss and Auditory Neuropathy Spectrum Disorder

PubMed Central

Gardner-Berry, Kirsty; Chang, Hsiuwen; Ching, Teresa Y. C.; Hou, Sanna

2016-01-01

With the introduction of newborn hearing screening, infants are being diagnosed with hearing loss during the first few months of life. For infants with a sensory/neural hearing loss (SNHL), the audiogram can be estimated objectively using auditory brainstem response (ABR) testing and hearing aids prescribed accordingly. However, for infants with auditory neuropathy spectrum disorder (ANSD) due to the abnormal/absent ABR waveforms, alternative measures of auditory function are needed to assess the need for amplification and evaluate whether aided benefit has been achieved. Cortical auditory evoked potentials (CAEPs) are used to assess aided benefit in infants with hearing loss; however, there is insufficient information regarding the relationship between stimulus audibility and CAEP detection rates. It is also not clear whether CAEP detection rates differ between infants with SNHL and infants with ANSD. This study involved retrospective collection of CAEP, hearing threshold, and hearing aid gain data to investigate the relationship between stimulus audibility and CAEP detection rates. The results demonstrate that increases in stimulus audibility result in an increase in detection rate. For the same range of sensation levels, there was no difference in the detection rates between infants with SNHL and ANSD. PMID:27587922

Coincidence-enhanced stochastic resonance: experimental evidence challenges the psychophysical theory behind stochastic resonance.

PubMed

Perez, Claudio A; Cohn, Theodore E; Medina, Leonel E; Donoso, José R

2007-08-31

Stochastic resonance (SR) is the counterintuitive phenomenon in which noise enhances detection of sub-threshold stimuli. The SR psychophysical threshold theory establishes that the required amplitude to exceed the sensory threshold barrier can be reached by adding noise to a sub-threshold stimulus. The aim of this study was to test the SR theory by comparing detection results from two different randomly-presented stimulus conditions. In the first condition, optimal noise was present during the whole attention interval; in the second, the optimal noise was restricted to the same time interval as the stimulus. SR threshold theory predicts no difference between the two conditions because noise helps the sub-threshold stimulus to reach threshold in both cases. The psychophysical experimental method used a 300 ms rectangular force pulse as a stimulus within an attention interval of 1.5 s, applied to the index finger of six human subjects in the two distinct conditions. For all subjects we show that in the condition in which the noise was present only when synchronized with the stimulus, detection was better (p<0.05) than in the condition in which the noise was delivered throughout the attention interval. These results provide the first direct evidence that SR threshold theory is incomplete and that a new phenomenon has been identified, which we call Coincidence-Enhanced Stochastic Resonance (CESR). We propose that CESR might occur because subject uncertainty is reduced when noise points at the same temporal window as the stimulus.

Effects of Response-Contingent Stimulus Pairing on Vocalizations of Nonverbal Children with Autism

ERIC Educational Resources Information Center

Lepper, Tracy L.; Petursdottir, Anna Ingeborg

2017-01-01

Research on stimulus-stimulus pairing to induce novel vocalizations in nonverbal children has typically employed response-independent pairing (RIP) procedures to condition speech sounds as reinforcers. The purpose of the present study was to evaluate the effects of a response-contingent pairing (RCP) procedure on the vocalizations of three…

Carving Executive Control At Its Joints: Working Memory Capacity Predicts Stimulus-Stimulus, But Not Stimulus-Response, Conflict

PubMed Central

Meier, Matt E.; Kane, Michael J.

2015-01-01

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

Carving executive control at its joints: Working memory capacity predicts stimulus-stimulus, but not stimulus-response, conflict.

PubMed

Meier, Matt E; Kane, Michael J

2015-11-01

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. (c) 2015 APA, all rights reserved).

Stimulus control by 5-methoxy-N,N-dimethyltryptamine in wild-type and CYP2D6-humanized mice.

PubMed

Winter, J C; Amorosi, D J; Rice, Kenner C; Cheng, Kejun; Yu, Ai-Ming

2011-09-01

In previous studies we have observed that, in comparison with wild type mice, Tg-CYP2D6 mice have increased serum levels of bufotenine [5-hydroxy-N,N-dimethyltryptamine] following the administration of 5-MeO-DMT. Furthermore, following the injection of 5-MeO-DMT, harmaline was observed to increase serum levels of bufotenine and 5-MeO-DMT in both wild-type and Tg-CYP2D6 mice. In the present investigation, 5-MeO-DMT-induced stimulus control was established in wild-type and Tg-CYP2D6 mice. The two groups did not differ in their rate of acquisition of stimulus control. When tested with bufotenine, no 5-MeO-DMT-appropriate responding was observed. In contrast, the more lipid soluble analog of bufotenine, acetylbufotenine, was followed by an intermediate level of responding. The combination of harmaline with 5-MeO-DMT yielded a statistically significant increase in 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice; a comparable increase occurred in wild-type mice. In addition, it was noted that harmaline alone was followed by a significant degree of 5-MeO-DMT-appropriate responding in Tg-CYP2D6 mice. It is concluded that wild-type and Tg-CYPD2D6 mice do not differ in terms of acquisition of stimulus control by 5-MeO-DMT or in their response to bufotenine and acetylbufotenine. In both groups of mice, harmaline was found to enhance the stimulus effects of 5-MeO-DMT. Copyright © 2011 Elsevier Inc. All rights reserved.

Motor cortical encoding of serial order in a context-recall task.

PubMed

Carpenter, A F; Georgopoulos, A P; Pellizzer, G

1999-03-12

The neural encoding of serial order was studied in the motor cortex of monkeys performing a context-recall memory scanning task. Up to five visual stimuli were presented successively on a circle (list presentation phase), and then one of them (test stimulus) changed color; the monkeys had to make a single motor response toward the stimulus that immediately followed the test stimulus in the list. Correct performance in this task depends on memorization of the serial order of the stimuli during their presentation. It was found that changes in neural activity during the list presentation phase reflected the serial order of the stimuli; the effect on cell activity of the serial order of stimuli during their presentation was at least as strong as the effect of motor direction on cell activity during the execution of the motor response. This establishes the serial order of stimuli in a motor task as an important determinant of motor cortical activity during stimulus presentation and in the absence of changes in peripheral motor events, in contrast to the commonly held view of the motor cortex as just an "upper motor neuron."

Separate and combined effects of gabapentin and Δ9-THC in humans discriminating Δ9-THC

PubMed Central

Lile, Joshua A.; Wesley, Michael J.; Kelly, Thomas H.; Hays, Lon R.

2015-01-01

The aim of the present study was to examine a potential mechanism of action of gabapentin to manage cannabis-use disorders by determining the interoceptive effects of gabapentin in cannabis users discriminating Δ9-THC using a pharmacologically selective drug-discrimination procedure. Eight cannabis users learned to discriminate 30 mg oral Δ9-THC from placebo and then received gabapentin (600 and 1200 mg), Δ9-THC (5, 15 and 30 mg) and placebo, alone and in combination. Self-report, task performance and physiological measures were also collected. Δ9-THC served as a discriminative stimulus, produced positive subjective effects, elevated heart rate and impaired psychomotor performance. Both doses of gabapentin substituted for the Δ9-THC discriminative stimulus and engendered subjective and performance-impairing effects that overlapped with those of Δ9-THC when administered alone. When administered concurrently, gabapentin shifted the discriminative-stimulus effects of Δ9-THC leftward/upward, and combinations of Δ9-THC and gabapentin generally produced larger effects on cannabinoid-sensitive outcomes relative to Δ9-THC alone. These results suggest that one mechanism by which gabapentin might facilitate cannabis abstinence is by producing effects that overlap with those of cannabinoids. PMID:26313650

State-space estimation of the input stimulus function using the Kalman filter: a communication system model for fMRI experiments.

PubMed

Ward, B Douglas; Mazaheri, Yousef

2006-12-15

The blood oxygenation level-dependent (BOLD) signal measured in functional magnetic resonance imaging (fMRI) experiments in response to input stimuli is temporally delayed and distorted due to the blurring effect of the voxel hemodynamic impulse response function (IRF). Knowledge of the IRF, obtained during the same experiment, or as the result of a separate experiment, can be used to dynamically obtain an estimate of the input stimulus function. Reconstruction of the input stimulus function allows the fMRI experiment to be evaluated as a communication system. The input stimulus function may be considered as a "message" which is being transmitted over a noisy "channel", where the "channel" is characterized by the voxel IRF. Following reconstruction of the input stimulus function, the received message is compared with the transmitted message on a voxel-by-voxel basis to determine the transmission error rate. Reconstruction of the input stimulus function provides insight into actual brain activity during task activation with less temporal blurring, and may be considered as a first step toward estimation of the true neuronal input function.

Teaching Stimulus Control via Class-Wide Multiple Schedules of Reinforcement in Public Elementary School Classrooms

ERIC Educational Resources Information Center

Torelli, Jessica N.; Lloyd, Blair P.; Diekman, Claire A.; Wehby, Joseph H.

2017-01-01

In elementary school classrooms, students commonly recruit teacher attention at inappropriately high rates or at inappropriate times. Multiple schedule interventions have been used to teach stimulus control by signaling to students when reinforcement is and is not available contingent on an appropriate response. The purpose of the current study…

Some Determinants of Remote Behavioral History Effects in Humans

ERIC Educational Resources Information Center

Hirai, Mariko; Okouchi, Hiroto; Matsumoto, Akio; Lattal, Kennon A.

2011-01-01

Undergraduates were exposed to a series of reinforcement schedules: first, to a fixed-ratio (FR) schedule in the presence of one stimulus and to a differential-reinforcement-of-low-rate (DRL) schedule in the presence of another (multiple FR DRL training), then to a fixed-interval (FI) schedule in the presence of a third stimulus (FI baseline),…

Identity matching in a patient with Alzheimer's disease.

PubMed

Steinunn Steingrimsdottir, Hanna; Arntzen, Erik

2011-05-01

Difficulties with short-term memory are one of the main problems in patients with dementia. Therefore, one purpose of this study was to examine the effects of simultaneous vs delayed presentation of comparison stimuli in a matching-to-sample (MTS) task using computerized training. By using an identity MTS procedure, the participant was trained to select a comparison stimulus identical to a sample stimulus. A 2nd purpose was to study the effect of the number of choices presented, thereby evaluating short-term memory deficits and possible deterioration of deficits over time. In this study, an 80-year-old-male with a Mini-Mental State Examination (MMSE) score of 10 was exposed to 4 experimental conditions. The results showed that using 3 comparison stimuli presented simultaneously with the sample stimulus on the screen resulted in more incorrect responding than when using 2 comparison stimuli. Furthermore, when adding a 0-second delay between the presentation of the sample stimulus and the 2 comparison stimuli, the number of correct responses did not exceed chance level.

Stimulus selectivity and response latency in putative inhibitory and excitatory neurons of the primate inferior temporal cortex

PubMed Central

Mruczek, Ryan E. B.

2012-01-01

The cerebral cortex is composed of many distinct classes of neurons. Numerous studies have demonstrated corresponding differences in neuronal properties across cell types, but these comparisons have largely been limited to conditions outside of awake, behaving animals. Thus the functional role of the various cell types is not well understood. Here, we investigate differences in the functional properties of two widespread and broad classes of cells in inferior temporal cortex of macaque monkeys: inhibitory interneurons and excitatory projection cells. Cells were classified as putative inhibitory or putative excitatory neurons on the basis of their extracellular waveform characteristics (e.g., spike duration). Consistent with previous intracellular recordings in cortical slices, putative inhibitory neurons had higher spontaneous firing rates and higher stimulus-evoked firing rates than putative excitatory neurons. Additionally, putative excitatory neurons were more susceptible to spike waveform adaptation following very short interspike intervals. Finally, we compared two functional properties of each neuron's stimulus-evoked response: stimulus selectivity and response latency. First, putative excitatory neurons showed stronger stimulus selectivity compared with putative inhibitory neurons. Second, putative inhibitory neurons had shorter response latencies compared with putative excitatory neurons. Selectivity differences were maintained and latency differences were enhanced during a visual search task emulating more natural viewing conditions. Our results suggest that short-latency inhibitory responses are likely to sculpt visual processing in excitatory neurons, yielding a sparser visual representation. PMID:22933717

Coding stimulus amplitude by correlated neural activity

NASA Astrophysics Data System (ADS)

Metzen, Michael G.; Ávila-Åkerberg, Oscar; Chacron, Maurice J.

2015-04-01

While correlated activity is observed ubiquitously in the brain, its role in neural coding has remained controversial. Recent experimental results have demonstrated that correlated but not single-neuron activity can encode the detailed time course of the instantaneous amplitude (i.e., envelope) of a stimulus. These have furthermore demonstrated that such coding required and was optimal for a nonzero level of neural variability. However, a theoretical understanding of these results is still lacking. Here we provide a comprehensive theoretical framework explaining these experimental findings. Specifically, we use linear response theory to derive an expression relating the correlation coefficient to the instantaneous stimulus amplitude, which takes into account key single-neuron properties such as firing rate and variability as quantified by the coefficient of variation. The theoretical prediction was in excellent agreement with numerical simulations of various integrate-and-fire type neuron models for various parameter values. Further, we demonstrate a form of stochastic resonance as optimal coding of stimulus variance by correlated activity occurs for a nonzero value of noise intensity. Thus, our results provide a theoretical explanation of the phenomenon by which correlated but not single-neuron activity can code for stimulus amplitude and how key single-neuron properties such as firing rate and variability influence such coding. Correlation coding by correlated but not single-neuron activity is thus predicted to be a ubiquitous feature of sensory processing for neurons responding to weak input.

Functional electrical stimulation to the abdominal wall muscles synchronized with the expiratory flow does not induce muscle fatigue.

PubMed

Okuno, Yukako; Takahashi, Ryoichi; Sewa, Yoko; Ohse, Hirotaka; Imura, Shigeyuki; Tomita, Kazuhide

2017-03-01

[Purpose] Continuous electrical stimulation of abdominal wall muscles is known to induce mild muscle fatigue. However, it is not clear whether this is also true for functional electrical stimulation delivered only during the expiratory phase of breathing. This study aimed to examine whether or not intermittent electrical stimulation delivered to abdominal wall muscles induces muscle fatigue. [Subjects and Methods] The subjects were nine healthy adults. Abdominal electrical stimulation was applied for 1.5 seconds from the start of expiration and then turned off during inspiration. The electrodes were attached to both sides of the abdomen at the lower margin of the 12th rib. Abdominal electrical stimulation was delivered for 15 minutes with the subject in a seated position. Expiratory flow was measured during stimulus. Trunk flexor torque and electromyography activity were measured to evaluate abdominal muscle fatigue. [Results] The mean stimulation on/off ratio was 1:2.3. The declining rate of abdominal muscle torque was 61.1 ± 19.1% before stimulus and 56.5 ± 20.9% after stimulus, not significantly different. The declining rate of mean power frequency was 47.8 ± 11.7% before stimulus and 47.9 ± 10.2% after stimulus, not significantly different. [Conclusion] It was found that intermittent electrical stimulation to abdominal muscles synchronized with the expiratory would not induce muscle fatigue.

Abnormal Vestibulo-Ocular Reflexes in Autism: A Potential Endophenotype

DTIC Science & Technology

2014-08-01

among. Saccades and smooth pursuit are complex sensorimotor behaviors that involve several spatially distant brain regions and long- fiber tracts between...time, at a rate of 100 Hz. Visual stimuli were presented as a red laser -light, generated by NKI Pursuit Tracker® laser . The Pursuit Tracker® laser ...the testing equipment by projecting a laser stimulus onto the cylindrical screen and providing a fixed target at + 10º in both the horizontal and

Multiecho Processing by an Echolocating Dolphin

DTIC Science & Technology

2003-08-01

with the number of stimulus information, is less clear (Dankiewicz et al., 2002; Moore presentations. etal., 1991; Roitblat etal., 1991). Dependence...W. B., Roitblat , H. L., Penner, R. H., and Nachtigall, P. E. (1991). ting yields a large false-alarm rate that cannot be changed "Recognizing... Roitblat , H. L., Moore, P. W. B., Nachtigall, P. E., and Penner, R. H. (1991). Au, W. W. L., and Banks, K. (1998). "The acoustics of the snapping shrimp

Discriminative stimuli that follow the absence of reinforcement are preferred by pigeons over those that follow reinforcement.

PubMed

Friedrich, Andrea M; Clement, Tricia S; Zentall, Thomas R

2005-08-01

Clement, Feltus, Kaiser, and Zentall (2000) found that when pigeons have to work to obtain a discriminative stimulus that is followed by reinforcement, they prefer a discriminative stimulus that requires greater effort over one that requires less effort. The authors suggested that such a preference results from the greater change in hedonic value that occurs between the more aversive event and the onset of the stimulus that signals reinforcement, a contrast effect. It was hypothesized that any stimulus that follows a relatively more aversive event would be preferred over a stimulus that follows a relatively less aversive event. In the present experiment, the authors tested the counterintuitive prediction of that theory, that pigeons should prefer a discriminative stimulus that follows the absence of reinforcement over a discriminative stimulus that follows reinforcement. Results supported the theory.

Dissociating Stimulus-Set and Response-Set in the Context of Task-Set Switching

PubMed Central

Kieffaber, Paul D.; Kruschke, John K.; Cho, Raymond Y.; Walker, Philip M.; Hetrick, William P.

2014-01-01

The primary aim of the present research was to determine how stimulus-set and response-set components of task-set contribute to switch costs and conflict processing. Three experiments are described wherein participants completed an explicitly cued task-switching procedure. Experiment 1 established that task switches requiring a reconfiguration of both stimulus- and response-set incurred larger residual switch costs than task switches requiring the reconfiguration of stimulus-set alone. Between-task interference was also drastically reduced for response-set conflict compared with stimulus-set conflict. A second experiment replicated these findings and demonstrated that stimulus- and response-conflict have dissociable effects on the “decision time” and “motor time” components of total response time. Finally, a third experiment replicated Experiment 2 and demonstrated that the stimulus- and response- components of task switching and conflict processing elicit dissociable neural activity as evidence by event-related brain potentials. PMID:22984990

Orthogonal stimulus-response compatibility effects emerge even when the stimulus position is task irrelevant.

PubMed

Nishimura, Akio; Yokosawa, Kazuhiko

2006-06-01

The above-right/below-left mapping advantage with vertical stimuli and horizontal responses is known as the orthogonal stimulus-response compatibility (SRC) effect. We investigated whether the orthogonal SRC effect emerges with irrelevant stimulus dimensions. In Experiment 1, participants responded with a right or left key press to the colour of the stimulus presented above or below the fixation. We observed an above-right/below-left advantage (orthogonal Simon effect). In Experiment 2, we manipulated the polarity in the response dimension by varying the horizontal location of the response set. The orthogonal Simon effect decreased and even reversed as the left response code became more positive. This result provides evidence for the automatic activation of the positive and negative response codes by the corresponding positive and negative stimulus codes. These findings extended the orthogonal SRC effect based on coding asymmetry to an irrelevant stimulus dimension.

Comparison of the discriminative stimulus and response rate effects of Δ9-tetrahydrocannabinol and synthetic cannabinoids in female and male rats.

PubMed

Wiley, Jenny L; Lefever, Timothy W; Marusich, Julie A; Craft, Rebecca M

2017-03-01

Women report greater sensitivity to the subjective effects of Δ 9 -tetrahydrocannabinol (THC). Similarly, female rodents tend to be more sensitive to some pharmacological effects of THC and synthetic cannabinoids. This study examined sex differences in discriminative stimulus and response rate effects of THC and synthetic cannabinoids in rats. A cumulative dosing THC discrimination procedure was utilized to evaluate sex differences in the discriminative stimulus effects of THC and three synthetic cannabinoids: CP47,497, WIN55,212-2, and JWH-018. Sex differences in the effects of these four compounds and a degradant of A-834735 on response rates also were assessed in a food-reinforced discrete dosing procedure. Females required a lower training dose than males for acquisition of the discrimination. Further, THC was more potent at producing rimonabant-reversible discriminative stimulus and response rate effects in females. While synthetic cannabinoids were more potent in producing THC-like effects than was THC in female rats, greater discrepancies were observed in male rats. Similar sensitivity to the response rate-decreasing effects induced by most, but not all (A-834735 degradant), synthetic cannabinoids was seen in both sexes. This study represents one of the first direct comparisons of sex differences in THC discrimination. Females were more sensitive to THC's effects, which may be related, in part, to sex differences in THC metabolism. Synthetic cannabinoids were more potent than THC in both sexes, but were considerably more so in male than in female rats. Future research should emphasize further characterization of sex differences in cannabinoid pharmacology. Copyright © 2017 Elsevier B.V. All rights reserved.

Comparison of the discriminative stimulus and response rate effects of Δ9-tetrahydrocannabinol and synthetic cannabinoids in female and male rats*

PubMed Central

Wiley, Jenny L.; Lefever, Timothy W.; Marusich, Julie A.; Craft, Rebecca M.

2017-01-01

Background Women report greater sensitivity to the subjective effects of Δ9-tetrahydrocannabinol (THC). Similarly, female rodents tend to be more sensitive to some pharmacological effects of THC and synthetic cannabinoids. This study examined sex differences in discriminative stimulus and response rate effects of THC and synthetic cannabinoids in rats. Methods A cumulative dosing THC discrimination procedure was utilized to evaluate sex differences in the discriminative stimulus effects of THC and three synthetic cannabinoids: CP47,497, WIN55,212-2, and JWH-018. Sex differences in the effects of these four compounds and a degradant of A-834735 on response rates also were assessed in a food-reinforced discrete dosing procedure. Results Females required a lower training dose than males for acquisition of the discrimination. Further, THC was more potent at producing rimonabant-reversible discriminative stimulus and response rate effects in females. While synthetic cannabinoids were more potent in producing THC-like effects than was THC in female rats, greater discrepancies were observed in male rats. Similar sensitivity to the response rate-decreasing effects induced by most, but not all (A-834735 degradant), synthetic cannabinoids was seen in both sexes. Conclusions This study represents one of the first direct comparisons of sex differences in THC discrimination. Females were more sensitive to THC’s effects, which may be related, in part, to sex differences in THC metabolism. Synthetic cannabinoids were more potent than THC in both sexes, but were considerably more so in male than in female rats. Future research should emphasize further characterization of sex differences in cannabinoid pharmacology. PMID:28130989

Discrepancy between stimulus response and tolerance of pain in Alzheimer disease

PubMed Central

Werner, Mads U.; Jensen, Troels Staehelin; Ballegaard, Martin; Andersen, Birgitte Bo; Høgh, Peter; Waldemar, Gunhild

2015-01-01

Background: Affective-motivational and sensory-discriminative aspects of pain were investigated in patients with mild to moderate Alzheimer disease (AD) and healthy elderly controls using the cold pressor test tolerance and repetitive stimuli of warmth and heat stimuli, evaluating the stimulus-response function. Methods: A case-control design was applied examining 33 patients with mild to moderate AD dementia and 32 healthy controls with the cold pressor test (4°C). Warmth detection threshold (WDT) and heat pain threshold (HPT) were assessed using 5 stimulations. A stimulus-response function was estimated using 4 incrementally increasing suprathreshold heat stimuli. Results: Cold pressor tolerance was lower in patients with AD dementia than in controls (p = 0.027). There were no significant differences between groups regarding WDT and HPT. Significant successive increases in HPT assessments indicated habituation (p < 0.0001), which was similar in the 2 groups (p = 0.85). A mixed model for repeated measures demonstrated that pain rating of suprathreshold stimuli depended on HPT (p = 0.0004) and stimulus intensity (p < 0.0001). Patients with AD dementia had significantly lower increases in pain ratings than controls during suprathreshold stimulation (p = 0.0072). Conclusion: Our results indicate that AD dementia is not associated with a propensity toward development of sensitization or a lack of habituation, suggesting preservation of sensory-discriminative aspects of pain perception. The results further suggest that the attenuated cold pressor pain tolerance may relate to impairment of coping abilities. Paradoxically, we found an attenuated stimulus-response function, compared to controls, suggesting that AD dementia interferes with pain ratings over time, most likely due to memory impairment. PMID:25788560

Short- and Long-Term Memories Formed upon Backward Conditioning in Honeybees ("Apis Mellifera")

ERIC Educational Resources Information Center

Felsenberg, Johannes; Plath, Jenny Aino; Lorang, Steven; Morgenstern, Laura; Eisenhardt, Dorothea

2014-01-01

In classical conditioning, the temporal sequence of stimulus presentations is critical for the association between the conditioned stimulus (CS) and the unconditioned stimulus (US). In forward conditioning, the CS precedes the US and is learned as a predictor for the US. Thus it acquires properties to elicit a behavioral response, defined as…

The Relationship between Stimulus and Response Prompts under Two Types of Programmed Presentations.

ERIC Educational Resources Information Center

Young, Jon I.; And Others

Prompts in concept classification normally occur on the stimulus, while in memorization tasks prompts customarily are given on the response. Opposite results have been obtained for these two tasks with excessive prompting. This study used English-Russian word pairs to compare stimulus prompts (underlining the English word) with response prompts in…

Beyond maximum speed—a novel two-stimulus paradigm for brain-computer interfaces based on event-related potentials (P300-BCI)

NASA Astrophysics Data System (ADS)

Kaufmann, Tobias; Kübler, Andrea

2014-10-01

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.

Brief Communication: visual-field superiority as a function of stimulus type and content: further evidence.

PubMed

Basu, Anamitra; Mandal, Manas K

2004-07-01

The present study examined visual-field advantage as a function of presentation mode (unilateral, bilateral), stimulus structure (facial, lexical), and stimulus content (emotional, neutral). The experiment was conducted in a split visual-field paradigm using a JAVA-based computer program with recognition accuracy as the dependent measure. Unilaterally, rather than bilaterally, presented stimuli were significantly better recognized. Words were significantly better recognized than faces in the right visual-field; the difference was nonsignificant in the left visual-field. Emotional content elicited left visual-field and neutral content elicited right visual-field advantages. Copyright Taylor and Francis Inc.

Stimulus Disparity and Punisher Control of Human Signal-Detection Performance

ERIC Educational Resources Information Center

Lie, Celia; Alsop, Brent

2010-01-01

The present experiment examined the effects of varying stimulus disparity and relative punisher frequencies on signal detection by humans. Participants were placed into one of two groups. Group 3 participants were presented with 1:3 and 3:1 punisher frequency ratios, while Group 11 participants were presented with 1:11 and 11:1 punisher frequency…

The selective dopamine uptake inhibitor, D-84, suppresses cocaine self-administration, but does not occasion cocaine-like levels of generalization

PubMed Central

Batman, Angela M.; Dutta, Aloke K.; Reith, Maarten E. A.; Beardsley, Patrick M.

2010-01-01

A successful replacement pharmacotherapy for treating cocaine dependency would likely reduce cocaine's abuse, support a low abuse liability, overlap cocaine's subjective effects, and have a long duration of action. Inhibitors with varying selectivity at the dopamine transporter (DAT) have approximated these properties. The objective of the present study was to characterize the behavioural effects of an extremely selective DAT inhibitor, (+) trans-4-(2-Benzhydryloxyethyl)-1-(4-fluorobenzyl) piperadin-3-ol (D-84), a 3-hydroxy substituted piperidine derivative of GBR-12935, for its cocaine-like discriminative stimulus effects, its effects on cocaine self-administration, and for its own self-administration. During cocaine discrimination tests, cocaine occasioned the 10 mg/kg cocaine training stimulus with an ED50 value of 3.13 (1.54-6.34) mg/kg, and reduced response rates with an ED50 value of 20.39 (7.24-57.44) mg/kg. D-84 incompletely generalized to the cocaine stimulus occasioning a maximal 76% cocaine lever responding, while reducing response rates with lower potency than cocaine (ED50=30.94 (12.34-77.60) mg/kg). Pretreatment with D-84 (9.6-30.4 mg/kg) significantly (P<0.05) reduced cocaine intake at 17.1 mg/kg D-84 when cocaine was self-administered at 0.5 mg/kg/infusion, and at 30.4 mg/kg D-84 when cocaine was self-administered at 0.1, 0.5 .and 1.0 mg/kg/infusion. During self-administration tests with D-84 (0.1-1 mg/kg/infusion), numbers of infusions significantly exceeded vehicle levels at 0.3 mg/kg/infusion. These results show that D-84 pre-treatment can decrease cocaine intake especially when high doses of cocaine are being self-administered. This observation, combined with its incomplete generalization to the cocaine discriminative stimulus and its reported long duration of action, provides a profile consistent with a potential replacement therapy for treating cocaine abusing patients. PMID:20840845

Dynamic Information Encoding With Dynamic Synapses in Neural Adaptation

PubMed Central

Li, Luozheng; Mi, Yuanyuan; Zhang, Wenhao; Wang, Da-Hui; Wu, Si

2018-01-01

Adaptation refers to the general phenomenon that the neural system dynamically adjusts its response property according to the statistics of external inputs. In response to an invariant stimulation, neuronal firing rates first increase dramatically and then decrease gradually to a low level close to the background activity. This prompts a question: during the adaptation, how does the neural system encode the repeated stimulation with attenuated firing rates? It has been suggested that the neural system may employ a dynamical encoding strategy during the adaptation, the information of stimulus is mainly encoded by the strong independent spiking of neurons at the early stage of the adaptation; while the weak but synchronized activity of neurons encodes the stimulus information at the later stage of the adaptation. The previous study demonstrated that short-term facilitation (STF) of electrical synapses, which increases the synchronization between neurons, can provide a mechanism to realize dynamical encoding. In the present study, we further explore whether short-term plasticity (STP) of chemical synapses, an interaction form more common than electrical synapse in the cortex, can support dynamical encoding. We build a large-size network with chemical synapses between neurons. Notably, facilitation of chemical synapses only enhances pair-wise correlations between neurons mildly, but its effect on increasing synchronization of the network can be significant, and hence it can serve as a mechanism to convey the stimulus information. To read-out the stimulus information, we consider that a downstream neuron receives balanced excitatory and inhibitory inputs from the network, so that the downstream neuron only responds to synchronized firings of the network. Therefore, the response of the downstream neuron indicates the presence of the repeated stimulation. Overall, our study demonstrates that STP of chemical synapse can serve as a mechanism to realize dynamical neural encoding. We believe that our study shed lights on the mechanism underlying the efficient neural information processing via adaptation. PMID:29636675

In search of the emotional face: anger versus happiness superiority in visual search.

PubMed

Savage, Ruth A; Lipp, Ottmar V; Craig, Belinda M; Becker, Stefanie I; Horstmann, Gernot

2013-08-01

Previous research has provided inconsistent results regarding visual search for emotional faces, yielding evidence for either anger superiority (i.e., more efficient search for angry faces) or happiness superiority effects (i.e., more efficient search for happy faces), suggesting that these results do not reflect on emotional expression, but on emotion (un-)related low-level perceptual features. The present study investigated possible factors mediating anger/happiness superiority effects; specifically search strategy (fixed vs. variable target search; Experiment 1), stimulus choice (Nimstim database vs. Ekman & Friesen database; Experiments 1 and 2), and emotional intensity (Experiment 3 and 3a). Angry faces were found faster than happy faces regardless of search strategy using faces from the Nimstim database (Experiment 1). By contrast, a happiness superiority effect was evident in Experiment 2 when using faces from the Ekman and Friesen database. Experiment 3 employed angry, happy, and exuberant expressions (Nimstim database) and yielded anger and happiness superiority effects, respectively, highlighting the importance of the choice of stimulus materials. Ratings of the stimulus materials collected in Experiment 3a indicate that differences in perceived emotional intensity, pleasantness, or arousal do not account for differences in search efficiency. Across three studies, the current investigation indicates that prior reports of anger or happiness superiority effects in visual search are likely to reflect on low-level visual features associated with the stimulus materials used, rather than on emotion. PsycINFO Database Record (c) 2013 APA, all rights reserved.

Behavioral analyses of wind-evoked escape of the cricket, Gryllodes sigillatus.

PubMed

Kanou, Masamichi; Konishi, Atsuko; Suenaga, Rie

2006-04-01

The wind-evoked escape behavior of the cricket Gryllodes sigillatus was investigated using an air puff stimulus. A high velocity air puff elicited the escape behavior in many crickets. The crickets tended to escape away from the stimulus source, but the direction was not accurately oriented 180 degrees from the stimulus. After bilateral cercal ablation, only a few crickets showed wind-evoked escape behavior, and their response rates did not increase even 19 days after ablation. Therefore, information on air motion detected by cercal filiform hairs is essential for triggering wind-evoked behavior. After unilateral cercal ablation, the 81.3% response rate of intact crickets decreased to 16.5%, that is, it decreased to almost 20% that of intact crickets. One week after unilateral cercal ablation, the response rate recovered to more than 60% that of intact crickets. However, the accuracy rate of the escape direction of G. sigillatus showed no change even immediately after the unilateral cercal ablation. Therefore, both cerci are not necessarily required to determine the escape direction. The behavioral characteristics of wind-evoked escape of G. sigillatus are compared with those of another species of cricket, Gryllus bimaculatus. The two species of cricket employ different strategies for wind-evoked escape.

Variability and Correlations in Primary Visual Cortical Neurons Driven by Fixational Eye Movements

PubMed Central

McFarland, James M.; Cumming, Bruce G.

2016-01-01

The ability to distinguish between elements of a sensory neuron's activity that are stimulus independent versus driven by the stimulus is critical for addressing many questions in systems neuroscience. This is typically accomplished by measuring neural responses to repeated presentations of identical stimuli and identifying the trial-variable components of the response as noise. In awake primates, however, small “fixational” eye movements (FEMs) introduce uncontrolled trial-to-trial differences in the visual stimulus itself, potentially confounding this distinction. Here, we describe novel analytical methods that directly quantify the stimulus-driven and stimulus-independent components of visual neuron responses in the presence of FEMs. We apply this approach, combined with precise model-based eye tracking, to recordings from primary visual cortex (V1), finding that standard approaches that ignore FEMs typically miss more than half of the stimulus-driven neural response variance, creating substantial biases in measures of response reliability. We show that these effects are likely not isolated to the particular experimental conditions used here, such as the choice of visual stimulus or spike measurement time window, and thus will be a more general problem for V1 recordings in awake primates. We also demonstrate that measurements of the stimulus-driven and stimulus-independent correlations among pairs of V1 neurons can be greatly biased by FEMs. These results thus illustrate the potentially dramatic impact of FEMs on measures of signal and noise in visual neuron activity and also demonstrate a novel approach for controlling for these eye-movement-induced effects. SIGNIFICANCE STATEMENT Distinguishing between the signal and noise in a sensory neuron's activity is typically accomplished by measuring neural responses to repeated presentations of an identical stimulus. For recordings from the visual cortex of awake animals, small “fixational” eye movements (FEMs) inevitably introduce trial-to-trial variability in the visual stimulus, potentially confounding such measures. Here, we show that FEMs often have a dramatic impact on several important measures of response variability for neurons in primary visual cortex. We also present an analytical approach for quantifying signal and noise in visual neuron activity in the presence of FEMs. These results thus highlight the importance of controlling for FEMs in studies of visual neuron function, and demonstrate novel methods for doing so. PMID:27277801

Unconscious Semantic Activation Depends on Feature-Specific Attention Allocation

ERIC Educational Resources Information Center

Spruyt, Adriaan; De Houwer, Jan; Everaert, Tom; Hermans, Dirk

2012-01-01

We examined whether semantic activation by subliminally presented stimuli is dependent upon the extent to which participants assign attention to specific semantic stimulus features and stimulus dimensions. Participants pronounced visible target words that were preceded by briefly presented, masked prime words. Both affective and non-affective…

Affective Priming with Auditory Speech Stimuli

ERIC Educational Resources Information Center

Degner, Juliane

2011-01-01

Four experiments explored the applicability of auditory stimulus presentation in affective priming tasks. In Experiment 1, it was found that standard affective priming effects occur when prime and target words are presented simultaneously via headphones similar to a dichotic listening procedure. In Experiment 2, stimulus onset asynchrony (SOA) was…

Strength-based criterion shifts in recognition memory.

PubMed

Singer, Murray

2009-10-01

In manipulations of stimulus strength between lists, a more lenient signal detection criterion is more frequently applied to a weak than to a strong stimulus class. However, with randomly intermixed weak and strong test probes, such a criterion shift often does not result. A procedure that has yielded delay-based within-list criterion shifts was applied to strength manipulations in recognition memory for categorized word lists. When participants made semantic ratings about each stimulus word, strength-based criterion shifts emerged regardless of whether words from pairs of categories were studied in separate blocks (Experiment 1) or in intermixed blocks (Experiment 2). In Experiment 3, the criterion shift persisted under the semantic-rating study task, but not under rote memorization. These findings suggest that continually adjusting the recognition decision criterion is cognitively feasible. They provide a technique for manipulating the criterion shift, and they identify competing theoretical accounts of these effects.

Prioritization of arbitrary faces associated to self: An EEG study.

PubMed

Woźniak, Mateusz; Kourtis, Dimitrios; Knoblich, Günther

2018-01-01

Behavioral and neuroimaging studies have demonstrated that people process preferentially self-related information such as an image of their own face. Furthermore, people rapidly incorporate stimuli into their self-representation even if these stimuli do not have an intrinsic relation to self. In the present study, we investigated the time course of the processes involved in preferential processing of self-related information. In two EEG experiments three unfamiliar faces were identified with verbal labels as either the participant, a friend, or a stranger. Afterwards, participants judged whether two stimuli presented in succession (ISI = 1500ms) matched. In experiment 1, faces were followed by verbal labels and in experiment 2, labels were followed by faces. Both experiments showed the same pattern of behavioral and electrophysiological results. If the first stimulus (face or label) was associated with self, reaction times were faster and the late frontal positivity following the first stimulus was more pronounced. The self-association of the second stimulus (label or face) did not affect response times. However, the central-parietal P3 following presentation of the second stimulus was more pronounced when the second stimulus was preceded by self-related first stimulus. These results indicate that even unfamiliar faces that are associated to self can activate a self-representation. Once the self-representation has been activated the processing of ensuing stimuli is facilitated, irrespective of whether they are associated with the self.

Prioritization of arbitrary faces associated to self: An EEG study

PubMed Central

Kourtis, Dimitrios; Knoblich, Günther

2018-01-01

Behavioral and neuroimaging studies have demonstrated that people process preferentially self-related information such as an image of their own face. Furthermore, people rapidly incorporate stimuli into their self-representation even if these stimuli do not have an intrinsic relation to self. In the present study, we investigated the time course of the processes involved in preferential processing of self-related information. In two EEG experiments three unfamiliar faces were identified with verbal labels as either the participant, a friend, or a stranger. Afterwards, participants judged whether two stimuli presented in succession (ISI = 1500ms) matched. In experiment 1, faces were followed by verbal labels and in experiment 2, labels were followed by faces. Both experiments showed the same pattern of behavioral and electrophysiological results. If the first stimulus (face or label) was associated with self, reaction times were faster and the late frontal positivity following the first stimulus was more pronounced. The self-association of the second stimulus (label or face) did not affect response times. However, the central-parietal P3 following presentation of the second stimulus was more pronounced when the second stimulus was preceded by self-related first stimulus. These results indicate that even unfamiliar faces that are associated to self can activate a self-representation. Once the self-representation has been activated the processing of ensuing stimuli is facilitated, irrespective of whether they are associated with the self. PMID:29293670

Phasic and tonic neuron ensemble codes for stimulus-environment conjunctions in the lateral entorhinal cortex.

PubMed

Pilkiw, Maryna; Insel, Nathan; Cui, Younghua; Finney, Caitlin; Morrissey, Mark D; Takehara-Nishiuchi, Kaori

2017-07-06

The lateral entorhinal cortex (LEC) is thought to bind sensory events with the environment where they took place. To compare the relative influence of transient events and temporally stable environmental stimuli on the firing of LEC cells, we recorded neuron spiking patterns in the region during blocks of a trace eyeblink conditioning paradigm performed in two environments and with different conditioning stimuli. Firing rates of some neurons were phasically selective for conditioned stimuli in a way that depended on which room the rat was in; nearly all neurons were tonically selective for environments in a way that depended on which stimuli had been presented in those environments. As rats moved from one environment to another, tonic neuron ensemble activity exhibited prospective information about the conditioned stimulus associated with the environment. Thus, the LEC formed phasic and tonic codes for event-environment associations, thereby accurately differentiating multiple experiences with overlapping features.

Comparing preference assessments: selection- versus duration-based preference assessment procedures.

PubMed

Kodak, Tiffany; Fisher, Wayne W; Kelley, Michael E; Kisamore, April

2009-01-01

In the current investigation, the results of a selection- and a duration-based preference assessment procedure were compared. A Multiple Stimulus With Replacement (MSW) preference assessment [Windsor, J., Piché, L. M., & Locke, P. A. (1994). Preference testing: A comparison of two presentation methods. Research in Developmental Disabilities, 15, 439-455] and a variation of a Free-Operant (FO) preference assessment procedure [Roane, H. S., Vollmer, T. R., Ringdahl, J. E., & Marcus, B. A. (1998). Evaluation of a brief stimulus preference assessment. Journal of Applied Behavior Analysis, 31, 605-620] were conducted with four participants. A reinforcer assessment was conducted to determine which preference assessment procedure identified the item that produced the highest rates of responding. The items identified as most highly preferred were different across preference assessment procedures for all participants. Results of the reinforcer assessment showed that the MSW identified the item that functioned as the most effective reinforcer for two participants.

Blind Braille readers mislocate tactile stimuli.

PubMed

Sterr, Annette; Green, Lisa; Elbert, Thomas

2003-05-01

In a previous experiment, we observed that blind Braille readers produce errors when asked to identify on which finger of one hand a light tactile stimulus had occurred. With the present study, we aimed to specify the characteristics of this perceptual error in blind and sighted participants. The experiment confirmed that blind Braille readers mislocalised tactile stimuli more often than sighted controls, and that the localisation errors occurred significantly more often at the right reading hand than at the non-reading hand. Most importantly, we discovered that the reading fingers showed the smallest error frequency, but the highest rate of stimulus attribution. The dissociation of perceiving and locating tactile stimuli in the blind suggests altered tactile information processing. Neuroplasticity, changes in tactile attention mechanisms as well as the idea that blind persons may employ different strategies for tactile exploration and object localisation are discussed as possible explanations for the results obtained.

The modeling and simulation of visuospatial working memory

PubMed Central

Liang, Lina; Zhang, Zhikang

2010-01-01

Camperi and Wang (Comput Neurosci 5:383–405, 1998) presented a network model for working memory that combines intrinsic cellular bistability with the recurrent network architecture of the neocortex. While Fall and Rinzel (Comput Neurosci 20:97–107, 2006) replaced this intrinsic bistability with a biological mechanism-Ca2+ release subsystem. In this study, we aim to further expand the above work. We integrate the traditional firing-rate network with Ca2+ subsystem-induced bistability, amend the synaptic weights and suggest that Ca2+ concentration only increase the efficacy of synaptic input but has nothing to do with the external input for the transient cue. We found that our network model maintained the persistent activity in response to a brief transient stimulus like that of the previous two models and the working memory performance was resistant to noise and distraction stimulus if Ca2+ subsystem was tuned to be bistable. PMID:22132045

Right-hemispheric dominance for processing extended non-linguistic frequency transitions.

PubMed

McKibbin, Katherine; Elias, Lorin J; Saucier, Deborah M; Engebregston, Delaine

2003-11-01

The left hemisphere is specialized for most linguistic tasks and the right hemisphere is specialized for many non-linguistic tasks, but the cause of these functional asymmetries is unknown. One of the stimulus factors that appears to influence these asymmetries is the rate at which stimuli change. In the present experiment, 41 participants completed the Fused Dichotic Words Test (FDWT) and a non-linguistic Frequency Transition Task (FTT) wherein the Frequency Transitions (FTs) were either rapid (40 ms) or relatively slow (200 ms). There was a right hemisphere advantage for slow FTs when the change was at the front of the stimulus, but no corresponding left hemisphere advantage for the rapid FTs. There was no relationship between either FTT and the left hemisphere advantage exhibited on the FDWT. This finding provides support for the position that the right hemisphere dominates tasks that require temporal processing over relatively long periods of time.

Why rate when you could compare? Using the "EloChoice" package to assess pairwise comparisons of perceived physical strength.

PubMed

Clark, Andrew P; Howard, Kate L; Woods, Andy T; Penton-Voak, Ian S; Neumann, Christof

2018-01-01

We introduce "EloChoice", a package for R which uses Elo rating to assess pairwise comparisons between stimuli in order to measure perceived stimulus characteristics. To demonstrate the package and compare results from forced choice pairwise comparisons to those from more standard single stimulus rating tasks using Likert (or Likert-type) items, we investigated perceptions of physical strength from images of male bodies. The stimulus set comprised images of 82 men standing on a raised platform with minimal clothing. Strength-related anthropometrics and grip strength measurements were available for each man in the set. UK laboratory participants (Study 1) and US online participants (Study 2) viewed all images in both a Likert rating task, to collect mean Likert scores, and a pairwise comparison task, to calculate Elo, mean Elo (mElo), and Bradley-Terry scores. Within both studies, Likert, Elo and Bradley-Terry scores were closely correlated to mElo scores (all rs > 0.95), and all measures were correlated with stimulus grip strength (all rs > 0.38) and body size (all rs > 0.59). However, mElo scores were less variable than Elo scores and were hundreds of times quicker to compute than Bradley-Terry scores. Responses in pairwise comparison trials were 2/3 quicker than in Likert tasks, indicating that participants found pairwise comparisons to be easier. In addition, mElo scores generated from a data set with half the participants randomly excluded produced very comparable results to those produced with Likert scores from the full participant set, indicating that researchers require fewer participants when using pairwise comparisons.

Unpaired Shocks during Extinction Weaken the Contextual Renewal of a Conditioned Discrimination

ERIC Educational Resources Information Center

Vervliet, Bram; Vansteenwegen, Deb; Hermans, Dirk

2010-01-01

Extinction is generally more fragile than conditioning, as illustrated by the contextual renewal effect. The traditional extinction procedure entails isolated presentations of the conditioned stimulus. Extinction may be boosted by adding isolated presentations of the unconditioned stimulus, as this should augment breaking the contingency between…

Are preference and resistance to change convergent expressions of stimulus value?

PubMed

Podlesnik, Christopher A; Jimenez-Gomez, Corina; Shahan, Timothy A

2013-07-01

Behavioral momentum theory asserts that preference and relative resistance to disruption depend on reinforcement rates and provide converging expressions of the conditioned value of discriminative stimuli. However, preference and resistance to disruption diverge when assessing preference during brief extinction probes. We expanded upon this opposing relation by arranging target stimuli signaling equal variable-interval schedules across components of a multiple schedule. We paired one target stimulus with a richer reinforced alternative and the other with a leaner alternative. Furthermore, we varied reinforcement rates for the paired alternatives to assess the effects of manipulating relative conditioned value on preference and resistance to disruption by presession feeding, intercomponent food, and extinction. We replicated the opposing relation between preference and resistance to disruption but varying reinforcement rates for the paired alternatives did not systematically affect preference or resistance to disruption beyond levels observed in our initial condition. Importantly, we found that only preference between the target stimuli was related to relative baseline response rates in the presence of those stimuli. These findings suggest that preference during extinction probes might reveal more about baseline response rates between concurrently available alternatives than relative conditioned value. Resistance to disruption, conversely, appears to better reflect conditioned value because it is less confounded with baseline response rates and is a function of all sources of reinforcement obtained in the presence of a stimulus context. © Society for the Experimental Analysis of Behavior.

Adaptation in the auditory midbrain of the barn owl (Tyto alba) induced by tonal double stimulation.

PubMed

Singheiser, Martin; Ferger, Roland; von Campenhausen, Mark; Wagner, Hermann

2012-02-01

During hunting, the barn owl typically listens to several successive sounds as generated, for example, by rustling mice. As auditory cells exhibit adaptive coding, the earlier stimuli may influence the detection of the later stimuli. This situation was mimicked with two double-stimulus paradigms, and adaptation was investigated in neurons of the barn owl's central nucleus of the inferior colliculus. Each double-stimulus paradigm consisted of a first or reference stimulus and a second stimulus (probe). In one paradigm (second level tuning), the probe level was varied, whereas in the other paradigm (inter-stimulus interval tuning), the stimulus interval between the first and second stimulus was changed systematically. Neurons were stimulated with monaural pure tones at the best frequency, while the response was recorded extracellularly. The responses to the probe were significantly reduced when the reference stimulus and probe had the same level and the inter-stimulus interval was short. This indicated response adaptation, which could be compensated for by an increase of the probe level of 5-7 dB over the reference level, if the latter was in the lower half of the dynamic range of a neuron's rate-level function. Recovery from adaptation could be best fitted with a double exponential showing a fast (1.25 ms) and a slow (800 ms) component. These results suggest that neurons in the auditory system show dynamic coding properties to tonal double stimulation that might be relevant for faithful upstream signal propagation. Furthermore, the overall stimulus level of the masker also seems to affect the recovery capabilities of auditory neurons. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

Formal or Informal? The Impact of Style of Dress and Forms of Address on Business Students' Perceptions of Professors

ERIC Educational Resources Information Center

Sebastian, Richard J.; Bristow, Dennis

2008-01-01

In this article, the authors examine the effects of style of dress, forms of address, and gender of the stimulus person on business students' perceptions of professors' attributes. Student participants (125 women, 132 men) rated the stimulus person on indexes of attractiveness, trustworthiness, credibility, and likeability. Style of dress and form…

Self-Reported Pleasantness Ratings and Examiner-Coded Defensiveness in Response to Touch in Children with ASD: Effects of Stimulus Material and Bodily Location

ERIC Educational Resources Information Center

Cascio, Carissa J.; Lorenzi, Jill; Baranek, Grace T.

2016-01-01

Tactile defensiveness, characterized by behavioral hyperresponsiveness and negative emotional responses to touch, is a common manifestation of aberrant sensory processing in autism spectrum disorders (ASD) and other developmental disabilities (DD). Variations in tactile defensiveness with the properties of the stimulus and the bodily site of…

Infants' Attention to Patterned Stimuli: Developmental Change from 3 to 12 Months of Age

ERIC Educational Resources Information Center

Courage, Mary L.; Reynolds, Greg D.; Richards, John E.

2006-01-01

To examine the development of look duration as a function of age and stimulus type, 14- to 52-week-old infants were shown static and dynamic versions of faces, Sesame Street material, and achromatic patterns for 20 s of accumulated looking. Heart rate was recorded during looking and parsed into stimulus orienting, sustained attention, and…

Sensory generalization and learning about novel colours by poultry chicks.

PubMed

Osorio, Daniel; Ham, Abigail D; Gonda, Zsusanna; Andrew, Richard J

2009-07-01

In nature animals constantly encounter novel stimuli and need to generalize from known stimuli. The animal may then learn about the novel stimulus. Hull (1947) suggested that as they learn animals distinguish knowledge based on direct experience from inference by generalization and in support of this view suggested that if a subject is directly trained to a stimulus subsequent extinction of responses is slower than when the response is based on generalization. Such an effect is also predicted by Bayesian models that relate the rate of learning to uncertainty in the estimate of stimulus value. We find support for this prediction when chicks learn about a novel colour (orange) if the initial evaluation is based on similarity to known colours (red, yellow). Specifically, if an expected food reward is absent the rate of extinction of the response to the novel stimulus exceeds that for the familiar colours. Interestingly, the change in relative preference for novel and familiar stimuli occurs after a delay of an hour. This type of delay has not, to our knowledge, been reported in previous studies of single-trial learning, but given its importance of generalization in natural behaviour this type of learning may have wide relevance.

A model for food and stimulus changes that signal time-based contingency changes.

PubMed

Cowie, Sarah; Davison, Michael; Elliffe, Douglas

2014-11-01

When the availability of reinforcers depends on time since an event, time functions as a discriminative stimulus. Behavioral control by elapsed time is generally weak, but may be enhanced by added stimuli that act as additional time markers. The present paper assessed the effect of brief and continuous added stimuli on control by time-based changes in the reinforcer differential, using a procedure in which the local reinforcer ratio reversed at a fixed time after the most recent reinforcer delivery. Local choice was enhanced by the presentation of the brief stimuli, even when the stimulus change signalled only elapsed time, but not the local reinforcer ratio. The effect of the brief stimulus presentations on choice decreased as a function of time since the most recent stimulus change. We compared the ability of several versions of a model of local choice to describe these data. The data were best described by a model which assumed that error in discriminating the local reinforcer ratio arose from imprecise discrimination of reinforcers in both time and space, suggesting that timing behavior is controlled not only by discrimination elapsed time, but by discrimination of the reinforcer differential in time. © Society for the Experimental Analysis of Behavior.

Stimulus Threat and Exposure Context Modulate the Effect of Mere Exposure on Approach Behaviors.

PubMed

Young, Steven G; Jones, Isaiah F; Claypool, Heather M

2016-01-01

Mere-exposure (ME) research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli), ME potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli), mere exposure facilitated approach only for initially neutral stimuli. These results suggest that ME effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the ME literature are discussed.

Stimulus Threat and Exposure Context Modulate the Effect of Mere Exposure on Approach Behaviors

PubMed Central

Young, Steven G.; Jones, Isaiah F.; Claypool, Heather M.

2016-01-01

Mere-exposure (ME) research has found that initially neutral objects made familiar are preferred relative to novel objects. Recent work extends these preference judgments into the behavioral domain by illustrating that mere exposure prompts approach-oriented behavior toward familiar stimuli. However, no investigations have examined the effect of mere exposure on approach-oriented behavior toward threatening stimuli. The current work examines this issue and also explores how exposure context interacts with stimulus threat to influence behavioral tendencies. In two experiments participants were presented with both mere-exposed and novel stimuli and approach speed was assessed. In the first experiment, when stimulus threat was presented in a homogeneous format (i.e., participants viewed exclusively neutral or threatening stimuli), ME potentiated approach behaviors for both neutral and threatening stimuli. However, in the second experiment, in which stimulus threat was presented in a heterogeneous fashion (i.e., participants viewed both neutral and threatening stimuli), mere exposure facilitated approach only for initially neutral stimuli. These results suggest that ME effects on approach behaviors are highly context sensitive and depend on both stimulus valence and exposure context. Further implications of these findings for the ME literature are discussed. PMID:27965614

An Evaluation of the Preferences of Individuals with Severe and Multiple Disabilities and the Teaching of Choice-Making Skills

ERIC Educational Resources Information Center

Eldeniz Çetin, Müzeyyen; Safak, Pinar

2017-01-01

The general purpose of the present study is to determine the relationship between direct and indirect preference assessments of individuals with severe and multiple disabilities (SMD) and the relationship between the direct preference assessments (single-stimulus, paired-stimulus, and multiple-stimulus) as applied to individuals with SMD, and to…

Failures to change stimulus evaluations by means of subliminal approach and avoidance training.

PubMed

Van Dessel, Pieter; De Houwer, Jan; Roets, Arne; Gast, Anne

2016-01-01

Previous research suggests that the repeated performance of approach and avoidance (AA) actions in response to a stimulus causes changes in stimulus evaluations. Kawakami, Phills, Steele, and Dovidio (2007) and Jones, Vilensky, Vasey, and Fazio (2013) provided evidence that these AA training effects occur even when stimuli are presented only subliminally. We also examined whether reliable AA training effects can be observed with subliminal stimulus presentations but added more sensitive checks of perceptual stimulus discriminability. Three experiments, including a direct replication of the study by Kawakami et al. (2007), failed to provide any evidence for effects of subliminal AA training on implicit or explicit evaluations. Bayesian analyses indicated that our data provide robust evidence that subliminal AA training does not cause changes in evaluations. In contrast, we observed changes in evaluations when participants were provided with (either correct or incorrect) information about the stimulus-action contingencies in the subliminal AA training task and when participants performed a supraliminal AA training task that allowed participants to detect these contingencies. These findings support the idea that contingency awareness is necessary for the occurrence of AA training effects. (c) 2016 APA, all rights reserved).

Presentation-order effects for aesthetic stimulus preference.

PubMed

Englund, Mats P; Hellström, Åke

2012-10-01

For preference comparisons of paired successive musical excerpts, Koh (American Journal of Psychology, 80, 171-185, 1967) found time-order effects (TOEs) that correlated negatively with stimulus valence-the first (vs. the second) of two unpleasant (vs. two pleasant) excerpts tended to be preferred. We present three experiments designed to investigate whether valence-level-dependent order effects for aesthetic preference (a) can be accounted for using Hellström's (e.g., Journal of Experimental Psychology: Human Perception and Performance, 5, 460-477, 1979) sensation-weighting (SW) model, (b) can be generalized to successive and to simultaneous visual stimuli, and (c) vary, in accordance with the stimulus weighting, with interstimulus interval (ISI; for successive stimuli) or stimulus duration (for simultaneous stimuli). Participants compared paired successive jingles (Exp. 1), successive color patterns (Exp. 2), and simultaneous color patterns (Exp. 3), selecting the preferred stimulus. The results were well described by the SW model, which provided a better fit than did two extended versions of the Bradley-Terry-Luce model. Experiments 1 and 2 revealed higher weights for the second stimulus than for the first, and negatively valence-level-dependent TOEs. In Experiment 3, there was no laterality effect on the stimulus weighting and no valence-level-dependent space-order effects (SOEs). In terms of the SW model, the valence-level-dependent TOEs can be explained as a consequence of differential stimulus weighting in combination with stimulus valence varying from low to high, and the absence of valence-level-dependent SOEs as a consequence of the absence of differential weighting. For successive stimuli, there were no important effects of ISI on weightings and TOEs, and, for simultaneous stimuli, duration had only a small effect on the weighting.

Sensory Prioritization in Rats: Behavioral Performance and Neuronal Correlates.

PubMed

Lee, Conrad C Y; Diamond, Mathew E; Arabzadeh, Ehsan

2016-03-16

Operating with some finite quantity of processing resources, an animal would benefit from prioritizing the sensory modality expected to provide key information in a particular context. The present study investigated whether rats dedicate attentional resources to the sensory modality in which a near-threshold event is more likely to occur. We manipulated attention by controlling the likelihood with which a stimulus was presented from one of two modalities. In a whisker session, 80% of trials contained a brief vibration stimulus applied to whiskers and the remaining 20% of trials contained a brief change of luminance. These likelihoods were reversed in a visual session. When a stimulus was presented in the high-likelihood context, detection performance increased and was faster compared with the same stimulus presented in the low-likelihood context. Sensory prioritization was also reflected in neuronal activity in the vibrissal area of primary somatosensory cortex: single units responded differentially to the whisker vibration stimulus when presented with higher probability compared with lower probability. Neuronal activity in the vibrissal cortex displayed signatures of multiplicative gain control and enhanced response to vibration stimuli during the whisker session. In conclusion, rats allocate priority to the more likely stimulus modality and the primary sensory cortex may participate in the redistribution of resources. Detection of low-amplitude events is critical to survival; for example, to warn prey of predators. To formulate a response, decision-making systems must extract minute neuronal signals from the sensory modality that provides key information. Here, we identify the behavioral and neuronal correlates of sensory prioritization in rats. Rats were trained to detect whisker vibrations or visual flickers. Stimuli were embedded in two contexts in which either visual or whisker modality was more likely to occur. When a stimulus was presented in the high-likelihood context, detection was faster and more reliable. Neuronal recording from the vibrissal cortex revealed enhanced representation of vibrations in the prioritized context. These results establish the rat as an alternative model organism to primates for studying attention. Copyright © 2016 the authors 0270-6474/16/363243-11$15.00/0.

Electric stimulus duration alters network-mediated responses depending on retinal ganglion cell type

NASA Astrophysics Data System (ADS)

Im, Maesoon; Werginz, Paul; Fried, Shelley I.

2018-06-01

Objective. To improve the quality of artificial vision that arises from retinal prostheses, it is important to bring electrically-elicited neural activity more in line with the physiological signaling patterns that arise normally in the healthy retina. Our previous study reported that indirect activation produces a closer match to physiological responses in ON retinal ganglion cells (RGCs) than in OFF cells (Im and Fried 2015 J. Physiol. 593 3677-96). This suggests that a preferential activation of ON RGCs would shape the overall retinal response closer to natural signaling. Recently, we found that changes to the rate at which stimulation was delivered could bias responses towards a stronger ON component (Im and Fried 2016a J. Neural Eng. 13 025002), raising the possibility that changes to other stimulus parameters can similarly bias towards stronger ON responses. Here, we explore the effects of changing stimulus duration on the responses in ON and OFF types of brisk transient (BT) and brisk sustained (BS) RGCs. Approach. We used cell-attached patch clamp to record RGC spiking in the isolated rabbit retina. Targeted RGCs were first classified as ON or OFF type by their light responses, and further sub-classified as BT or BS types by their responses to both light and electric stimuli. Spiking in targeted RGCs was recorded in response to electric pulses with durations varying from 5 to100 ms. Stimulus amplitude was adjusted at each duration to hold total charge constant for all experiments. Main results. We found that varying stimulus durations modulated responses differentially for ON versus OFF cells: in ON cells, spike counts decreased significantly with increasing stimulus duration while in OFF cells the changes were more modest. The maximum ratio of ON versus OFF responses occurred at a duration of ~10 ms. The difference in response strength for BT versus BS cells was much larger in ON cells than in OFF cells. Significance. The stimulation rates preferred by subjects during clinical trials are similar to the rates that maximize the ON/OFF response ratio in in vitro testing (Im and Fried 2016a J. Neural Eng. 13 025002). Here, we determine the stimulus duration that produces the strongest bias towards ON responses and speculate that it will further enhance clinical effectiveness.

Stimulus size and eccentricity in visually induced perception of horizontally translational self-motion.

PubMed

Nakamura, S; Shimojo, S

1998-10-01

The effects of the size and eccentricity of the visual stimulus upon visually induced perception of self-motion (vection) were examined with various sizes of central and peripheral visual stimulation. Analysis indicated the strength of vection increased linearly with the size of the area in which the moving pattern was presented, but there was no difference in vection strength between central and peripheral stimuli when stimulus sizes were the same. Thus, the effect of stimulus size is homogeneous across eccentricities in the visual field.

Effect of administration of corticotropin-releasing hormone and glucocorticoid on arginine vasopressin response to osmotic stimulus in normal subjects and patients with hypocorticotropinism without overt diabetes insipidus.

PubMed

Yamada, K; Tamura, Y; Yoshida, S

1989-08-01

We examined the effect of CRH administration on the response of plasma arginine vasopressin (AVP) induced by an osmotic stimulus in six normal subjects and five patients with hypocorticotropinism without overt diabetes insipidus (four patients with Sheehan's syndrome and one with idiopathic pituitary dwarfism with ACTH deficiency). Hypertonic saline infusion (855 mmol/L saline solutions at a rate of 205 mumol/kg.min for 10 min) increased plasma AVP 5.7-fold (P less than 0.01) in normal subjects and 2.4-fold (P less than 0.05) in the patients. CRH administration significantly augmented the plasma AVP response to the osmotic stimulus in the normal subjects, but not in the patients with hypocorticotropinism. CRH administration alone did not influence plasma AVP. These findings suggest that a central CRH-related mechanism(s) was at least partly involved in the augmentation of AVP release. Based on the relatively low plasma AVP response to the osmotic stimulus in patients and their lower plasma AVP levels and higher plasma osmolality under basal conditions, we suggest that patients with hypocorticotropinism have partial diabetes insipidus, in which impairment of central CRH action might be, at least in part, involved. The response of plasma AVP to the osmotic stimulus was attenuated significantly when the patients were given cortisol. Since basal PRA, plasma aldosterone, plasma osmolality, hematocrit, body weight, mean blood pressure, and heart rate were similar with and without cortisol administration, this effect of cortisol may have been due to central suppression of the AVP response to the osmotic stimulus.

DETECTION AND IDENTIFICATION OF SPEECH SOUNDS USING CORTICAL ACTIVITY PATTERNS

PubMed Central

Centanni, T.M.; Sloan, A.M.; Reed, A.C.; Engineer, C.T.; Rennaker, R.; Kilgard, M.P.

2014-01-01

We have developed a classifier capable of locating and identifying speech sounds using activity from rat auditory cortex with an accuracy equivalent to behavioral performance without the need to specify the onset time of the speech sounds. This classifier can identify speech sounds from a large speech set within 40 ms of stimulus presentation. To compare the temporal limits of the classifier to behavior, we developed a novel task that requires rats to identify individual consonant sounds from a stream of distracter consonants. The classifier successfully predicted the ability of rats to accurately identify speech sounds for syllable presentation rates up to 10 syllables per second (up to 17.9 ± 1.5 bits/sec), which is comparable to human performance. Our results demonstrate that the spatiotemporal patterns generated in primary auditory cortex can be used to quickly and accurately identify consonant sounds from a continuous speech stream without prior knowledge of the stimulus onset times. Improved understanding of the neural mechanisms that support robust speech processing in difficult listening conditions could improve the identification and treatment of a variety of speech processing disorders. PMID:24286757

Effects of conditioned reinforcement frequency in an intermittent free-feeding situation, 12

PubMed Central

Zimmerman, Joseph; Hanford, Peter V.; Brown, Wyman

1967-01-01

Key-pecking intermittently produced a set of brief exteroceptive stimulus changes under two-component multiple schedules of conditioned reinforcement. Throughout the study, free access to grain was concurrently provided on an intermittent basis via a variable-interval tape. Free food presentations scheduled by the tape were delivered if no peck had been emitted for 6 sec, and the brief stimulus changes produced by responding under the multiple schedules were those which accompanied food presentation. The second component of each multiple schedule was always associated with a 1-min, variable-interval schedule of conditioned reinforcement. The schedule associated with the first component was systematically varied and conditioned reinforcement was either absent (extinction) or programmed on a 1-, 3-, 6-, or 12-min variable-interval schedule. Under these conditions, rate of responding in the manipulated component decreased monotonically with a decrease in the frequency of conditioned reinforcement. In addition, contrast effects were often obtained in the constant, second component. These results are similar to those obtained with similar multiple schedules of primary reinforcement. PMID:6033554

Stimulus Suffix Effects in Dichotic Memory

ERIC Educational Resources Information Center

Parkinson, Stanley R.; Hubbard, Lora L.

1974-01-01

in the present dichotic memory research, the addition of either a monaural stimulus suffix on the unattended ear or a binaural suffix was shown to selectively impair unattended-ear performance. (Editor)

Influence of double stimulation on sound-localization behavior in barn owls.

PubMed

Kettler, Lutz; Wagner, Hermann

2014-12-01

Barn owls do not immediately approach a source after they hear a sound, but wait for a second sound before they strike. This represents a gain in striking behavior by avoiding responses to random incidents. However, the first stimulus is also expected to change the threshold for perceiving the subsequent second sound, thus possibly introducing some costs. We mimicked this situation in a behavioral double-stimulus paradigm utilizing saccadic head turns of owls. The first stimulus served as an adapter, was presented in frontal space, and did not elicit a head turn. The second stimulus, emitted from a peripheral source, elicited the head turn. The time interval between both stimuli was varied. Data obtained with double stimulation were compared with data collected with a single stimulus from the same positions as the second stimulus in the double-stimulus paradigm. Sound-localization performance was quantified by the response latency, accuracy, and precision of the head turns. Response latency was increased with double stimuli, while accuracy and precision were decreased. The effect depended on the inter-stimulus interval. These results suggest that waiting for a second stimulus may indeed impose costs on sound localization by adaptation and this reduces the gain obtained by waiting for a second stimulus.

Spatial parameters at the basis of social transfer of learning.

PubMed

Lugli, Luisa; Iani, Cristina; Milanese, Nadia; Sebanz, Natalie; Rubichi, Sandro

2015-06-01

Recent research indicates that practicing on a joint spatial compatibility task with an incompatible stimulus-response mapping affects subsequent joint Simon task performance, eliminating the social Simon effect. It has been well established that in individual contexts, for transfer of learning to occur, participants need to practice an incompatible association between stimulus and response positions. The mechanisms underlying transfer of learning in joint task performance are, however, less well understood. The present study was aimed at assessing the relative contribution of 3 different spatial relations characterizing the joint practice context: stimulus-response, stimulus-participant, and participant-response relations. In 3 experiments, the authors manipulated the stimulus-response, stimulus-participant, and response-participant associations. We found that learning from the practice task did not transfer to the subsequent task when during practice stimulus-response associations were spatially incompatible and stimulus-participant associations were compatible (Experiment 1). However, a transfer of learning was evident when stimulus-participant associations were spatially incompatible. This occurred both when response-participant associations were incompatible (Experiment 2) and when they were compatible (Experiment 3). These results seem to support an agent corepresentation account of correspondence effects emerging in joint settings since they suggest that, in social contexts, critical to obtain transfer-of-learning effects is the spatial relation between stimulus and participant positions while the spatial relation between stimulus and response positions is irrelevant. (c) 2015 APA, all rights reserved).

Fitting of dynamic recurrent neural network models to sensory stimulus-response data.

PubMed

Doruk, R Ozgur; Zhang, Kechen

2018-06-02

We present a theoretical study aiming at model fitting for sensory neurons. Conventional neural network training approaches are not applicable to this problem due to lack of continuous data. Although the stimulus can be considered as a smooth time-dependent variable, the associated response will be a set of neural spike timings (roughly the instants of successive action potential peaks) that have no amplitude information. A recurrent neural network model can be fitted to such a stimulus-response data pair by using the maximum likelihood estimation method where the likelihood function is derived from Poisson statistics of neural spiking. The universal approximation feature of the recurrent dynamical neuron network models allows us to describe excitatory-inhibitory characteristics of an actual sensory neural network with any desired number of neurons. The stimulus data are generated by a phased cosine Fourier series having a fixed amplitude and frequency but a randomly shot phase. Various values of amplitude, stimulus component size, and sample size are applied in order to examine the effect of the stimulus to the identification process. Results are presented in tabular and graphical forms at the end of this text. In addition, to demonstrate the success of this research, a study involving the same model, nominal parameters and stimulus structure, and another study that works on different models are compared to that of this research.

Audiovisual semantic congruency during encoding enhances memory performance.

PubMed

Heikkilä, Jenni; Alho, Kimmo; Hyvönen, Heidi; Tiippana, Kaisa

2015-01-01

Studies of memory and learning have usually focused on a single sensory modality, although human perception is multisensory in nature. In the present study, we investigated the effects of audiovisual encoding on later unisensory recognition memory performance. The participants were to memorize auditory or visual stimuli (sounds, pictures, spoken words, or written words), each of which co-occurred with either a semantically congruent stimulus, incongruent stimulus, or a neutral (non-semantic noise) stimulus in the other modality during encoding. Subsequent memory performance was overall better when the stimulus to be memorized was initially accompanied by a semantically congruent stimulus in the other modality than when it was accompanied by a neutral stimulus. These results suggest that semantically congruent multisensory experiences enhance encoding of both nonverbal and verbal materials, resulting in an improvement in their later recognition memory.

A survey of the dummy face and human face stimuli used in BCI paradigm.

PubMed

Chen, Long; Jin, Jing; Zhang, Yu; Wang, Xingyu; Cichocki, Andrzej

2015-01-15

It was proved that the human face stimulus were superior to the flash only stimulus in BCI system. However, human face stimulus may lead to copyright infringement problems and was hard to be edited according to the requirement of the BCI study. Recently, it was reported that facial expression changes could be done by changing a curve in a dummy face which could obtain good performance when it was applied to visual-based P300 BCI systems. In this paper, four different paradigms were presented, which were called dummy face pattern, human face pattern, inverted dummy face pattern and inverted human face pattern, to evaluate the performance of the dummy faces stimuli compared with the human faces stimuli. The key point that determined the value of dummy faces in BCI systems were whether dummy faces stimuli could obtain as good performance as human faces stimuli. Online and offline results of four different paradigms would have been obtained and comparatively analyzed. Online and offline results showed that there was no significant difference among dummy faces and human faces in ERPs, classification accuracy and information transfer rate when they were applied in BCI systems. Dummy faces stimuli could evoke large ERPs and obtain as high classification accuracy and information transfer rate as the human faces stimuli. Since dummy faces were easy to be edited and had no copyright infringement problems, it would be a good choice for optimizing the stimuli of BCI systems. Copyright © 2014 Elsevier B.V. All rights reserved.

School-aged children can benefit from audiovisual semantic congruency during memory encoding.

PubMed

Heikkilä, Jenni; Tiippana, Kaisa

2016-05-01

Although we live in a multisensory world, children's memory has been usually studied concentrating on only one sensory modality at a time. In this study, we investigated how audiovisual encoding affects recognition memory. Children (n = 114) from three age groups (8, 10 and 12 years) memorized auditory or visual stimuli presented with a semantically congruent, incongruent or non-semantic stimulus in the other modality during encoding. Subsequent recognition memory performance was better for auditory or visual stimuli initially presented together with a semantically congruent stimulus in the other modality than for stimuli accompanied by a non-semantic stimulus in the other modality. This congruency effect was observed for pictures presented with sounds, for sounds presented with pictures, for spoken words presented with pictures and for written words presented with spoken words. The present results show that semantically congruent multisensory experiences during encoding can improve memory performance in school-aged children.

N2pc is modulated by stimulus-stimulus, but not by stimulus-response incompatibilities.

PubMed

Cespón, J; Galdo-Álvarez, S; Díaz, F

2013-04-01

Studies of the N2pc in Simon-type tasks have revealed inconsistent results. That is, N2pc was only modulated when a stimulus-stimulus (S-S) overlap covaries with the stimulus-response (S-R) overlap. The present study aimed to establish whether N2pc is modulated by the S-R or by the S-S overlap. Therefore, we designed a Simon task requiring response to a colour stimulus (an arrow) with two irrelevant dimensions (position and direction). The following conditions were thus generated: compatible direction-compatible position (CDCP); incompatible direction-compatible position (IDCP); compatible direction-incompatible position (CDIP); and incompatible direction-incompatible position (IDIP). In IDCP and CDIP, both irrelevant dimensions conveyed contradictory spatial information (S-S incompatibility), while compatibility between both irrelevant dimensions occurred in CDCP and IDIP (the direction indicated was compatible with stimulus position). The N2pc amplitude was smaller in IDCP and CDIP than in CDCP and IDIP, what suggests that N2pc was modulated by S-S incompatibility and not by S-R incompatibilities. Copyright © 2013 Elsevier B.V. All rights reserved.

Event-related potential N270 correlates of brand extension.

PubMed

Ma, Qingguo; Wang, Xiaoyi; Dai, Shenyi; Shu, Liangchao

2007-07-02

The aim of this study is to investigate the neural mechanism of extending a brand in a specific product category to other product categories. Facing two sequential stimuli in pairs consisting of beverage brand names (stimulus 1) and product names (stimulus 2) in other categories, 16 participants were asked to indicate the suitability of extending the brand in stimulus 1 to the product category in stimulus 2. These stimulus pairs were divided into four conditions depending on the product category in stimulus 2: beverage, snack, clothing, and household appliance. A negative component, N270, was recorded for each condition on the participants' scalps,whereas the maximum amplitude was observed at the frontal area. Greater N270 amplitude was observed when participants were presented with stronger conflict between the brand product category (stimulus 1) and the extension category (stimulus 2). It suggests that N270 can be evoked not only by a conflict of physical attributes (different shapes of words of brand and product names) but also by that of lexical content. From the marketing perspective, N270 can be potentially used as a reference measure in brand-extension attempts.

Disabled vs nondisabled readers: perceptual vs higher-order processing of one vs three letters.

PubMed

Allegretti, C L; Puglisi, J T

1986-10-01

12 disabled and 12 nondisabled readers (mean age, 11 yr.) were compared on a letter-search task which separated perceptual processing from higher-order processing. Participants were presented a first stimulus (for 200 msec. to minimize eye movements) followed by a second stimulus immediately to estimate the amount of information initially perceived or after a 3000-msec. interval to examine information more permanently stored. Participants were required to decide whether any letter present in the first stimulus was also present in the second. Two processing loads (1 and 3 letters) were examined. Disabled readers showed more pronounced deficits when they were given very little time to process information or more information to process.

Conditioned [corrected] stimulus informativeness governs conditioned stimulus-unconditioned stimulus associability.

PubMed

Ward, Ryan D; Gallistel, C R; Jensen, Greg; Richards, Vanessa L; Fairhurst, Stephen; Balsam, Peter D

2012-07-01

In a conditioning protocol, the onset of the conditioned stimulus ([CS]) provides information about when to expect reinforcement (unconditioned stimulus [US]). There are two sources of information from the CS in a delay conditioning paradigm in which the CS-US interval is fixed. The first depends on the informativeness, the degree to which CS onset reduces the average expected time to onset of the next US. The second depends only on how precisely a subject can represent a fixed-duration interval (the temporal Weber fraction). In three experiments with mice, we tested the differential impact of these two sources of information on rate of acquisition of conditioned responding (CS-US associability). In Experiment 1, we showed that associability (the inverse of trials to acquisition) increased in proportion to informativeness. In Experiment 2, we showed that fixing the duration of the US-US interval or the CS-US interval or both had no effect on associability. In Experiment 3, we equated the increase in information produced by varying the C/T ratio with the increase produced by fixing the duration of the CS-US interval. Associability increased with increased informativeness, but, as in Experiment 2, fixing the CS-US duration had no effect on associability. These results are consistent with the view that CS-US associability depends on the increased rate of reward signaled by CS onset. The results also provide further evidence that conditioned responding is temporally controlled when it emerges.

Effects of set-size and selective spatial attention on motion processing.

PubMed

Dobkins, K R; Bosworth, R G

2001-05-01

In order to investigate the effects of divided attention and selective spatial attention on motion processing, we obtained direction-of-motion thresholds using a stochastic motion display under various attentional manipulations and stimulus durations (100-600 ms). To investigate divided attention, we compared motion thresholds obtained when a single motion stimulus was presented in the visual field (set-size=1) to those obtained when the motion stimulus was presented amongst three confusable noise distractors (set-size=4). The magnitude of the observed detriment in performance with an increase in set-size from 1 to 4 could be accounted for by a simple decision model based on signal detection theory, which assumes that attentional resources are not limited in capacity. To investigate selective attention, we compared motion thresholds obtained when a valid pre-cue alerted the subject to the location of the to-be-presented motion stimulus to those obtained when no pre-cue was provided. As expected, the effect of pre-cueing was large when the visual field contained noise distractors, an effect we attribute to "noise reduction" (i.e. the pre-cue allows subjects to exclude irrelevant distractors that would otherwise impair performance). In the single motion stimulus display, we found a significant benefit of pre-cueing only at short durations (< or =150 ms), a result that can potentially be explained by a "time-to-orient" hypothesis (i.e. the pre-cue improves performance by eliminating the time it takes to orient attention to a peripheral stimulus at its onset, thereby increasing the time spent processing the stimulus). Thus, our results suggest that the visual motion system can analyze several stimuli simultaneously without limitations on sensory processing per se, and that spatial pre-cueing serves to reduce the effects of distractors and perhaps increase the effective processing time of the stimulus.

Effects of visual cue and response assignment on spatial stimulus coding in stimulus-response compatibility.

PubMed

Nishimura, Akio; Yokosawa, Kazuhiko

2012-01-01

Tlauka and McKenna ( 2000 ) reported a reversal of the traditional stimulus-response compatibility (SRC) effect (faster responding to a stimulus presented on the same side than to one on the opposite side) when the stimulus appearing on one side of a display is a member of a superordinate unit that is largely on the opposite side. We investigated the effects of a visual cue that explicitly shows a superordinate unit, and of assignment of multiple stimuli within each superordinate unit to one response, on the SRC effect based on superordinate unit position. Three experiments revealed that stimulus-response assignment is critical, while the visual cue plays a minor role, in eliciting the SRC effect based on the superordinate unit position. Findings suggest bidirectional interaction between perception and action and simultaneous spatial stimulus coding according to multiple frames of reference, with contribution of each coding to the SRC effect flexibly varying with task situations.

Inverse Target- and Cue-Priming Effects of Masked Stimuli

ERIC Educational Resources Information Center

Mattler, Uwe

2007-01-01

The processing of a visual target that follows a briefly presented prime stimulus can be facilitated if prime and target stimuli are similar. In contrast to these positive priming effects, inverse priming effects (or negative compatibility effects) have been found when a mask follows prime stimuli before the target stimulus is presented: Responses…

Components of Attention Modulated by Temporal Expectation

ERIC Educational Resources Information Center

Sørensen, Thomas Alrik; Vangkilde, Signe; Bundesen, Claus

2015-01-01

By varying the probabilities that a stimulus would appear at particular times after the presentation of a cue and modeling the data by the theory of visual attention (Bundesen, 1990), Vangkilde, Coull, and Bundesen (2012) provided evidence that the speed of encoding a singly presented stimulus letter into visual short-term memory (VSTM) is…

Time-resolved neuroimaging of visual short term memory consolidation by post-perceptual attention shifts.

PubMed

Hecht, Marcus; Thiemann, Ulf; Freitag, Christine M; Bender, Stephan

2016-01-15

Post-perceptual cues can enhance visual short term memory encoding even after the offset of the visual stimulus. However, both the mechanisms by which the sensory stimulus characteristics are buffered as well as the mechanisms by which post-perceptual selective attention enhances short term memory encoding remain unclear. We analyzed late post-perceptual event-related potentials (ERPs) in visual change detection tasks (100ms stimulus duration) by high-resolution ERP analysis to elucidate these mechanisms. The effects of early and late auditory post-cues (300ms or 850ms after visual stimulus onset) as well as the effects of a visual interference stimulus were examined in 27 healthy right-handed adults. Focusing attention with post-perceptual cues at both latencies significantly improved memory performance, i.e. sensory stimulus characteristics were available for up to 850ms after stimulus presentation. Passive watching of the visual stimuli without auditory cue presentation evoked a slow negative wave (N700) over occipito-temporal visual areas. N700 was strongly reduced by a visual interference stimulus which impeded memory maintenance. In contrast, contralateral delay activity (CDA) still developed in this condition after the application of auditory post-cues and was thereby dissociated from N700. CDA and N700 seem to represent two different processes involved in short term memory encoding. While N700 could reflect visual post processing by automatic attention attraction, CDA may reflect the top-down process of searching selectively for the required information through post-perceptual attention. Copyright © 2015 Elsevier Inc. All rights reserved.

Stimulus-related activity during conditional associations in monkey perirhinal cortex neurons depends on upcoming reward outcome.

PubMed

Ohyama, Kaoru; Sugase-Miyamoto, Yasuko; Matsumoto, Narihisa; Shidara, Munetaka; Sato, Chikara

2012-11-28

Acquiring the significance of events based on reward-related information is critical for animals to survive and to conduct social activities. The importance of the perirhinal cortex for reward-related information processing has been suggested. To examine whether or not neurons in this cortex represent reward information flexibly when a visual stimulus indicates either a rewarded or unrewarded outcome, neuronal activity in the macaque perirhinal cortex was examined using a conditional-association cued-reward task. The task design allowed us to study how the neuronal responses depended on the animal's prediction of whether it would or would not be rewarded. Two visual stimuli, a color stimulus as Cue1 followed by a pattern stimulus as Cue2, were sequentially presented. Each pattern stimulus was conditionally associated with both rewarded and unrewarded outcomes depending on the preceding color stimulus. We found an activity depending upon the two reward conditions during Cue2, i.e., pattern stimulus presentation. The response appeared after the response dependent upon the image identity of Cue2. The response delineating a specific cue sequence also appeared between the responses dependent upon the identity of Cue2 and reward conditions. Thus, when Cue1 sets the context for whether or not Cue2 indicates a reward, this region represents the meaning of Cue2, i.e., the reward conditions, independent of the identity of Cue2. These results suggest that neurons in the perirhinal cortex do more than associate a single stimulus with a reward to achieve flexible representations of reward information.

In vivo stimulus presentation to the mouse vomeronasal system: Surgery, experiment, setup, and software.

PubMed

Yoles-Frenkel, Michal; Cohen, Oksana; Bansal, Rohini; Horesh, Noa; Ben-Shaul, Yoram

2017-06-15

Achieving controlled stimulus delivery is a major challenge in the physiological analysis of the vomeronasal system (VNS). We provide a comprehensive description of a setup allowing controlled stimulus delivery into the vomeronasal organ (VNO) of anesthetized mice. VNO suction is achieved via electrical stimulation of the sympathetic nerve trunk (SNT) using cuff electrodes, followed by flushing of the nasal cavity. Successful application of this methodology depends on several aspects including the surgical preparation, fabrication of cuff electrodes, experimental setup modifications, and the stimulus delivery and flushing. Here, we describe all these aspects in sufficient detail to allow other researchers to readily adopt it. We also present a custom written MATLAB based software with a graphical user interface that controls all aspects of the actual experiment, including trial sequencing, hardware control, and data logging. The method allows measurement of stimulus evoked sensory responses in brain regions that receive vomeronasal inputs. An experienced investigator can complete the entire surgical procedure within thirty minutes. This is the only approach that allows repeated and controlled stimulus delivery to the intact VNO, employing the natural mode of stimulus uptake. The approach is economical with respect to stimuli, requiring stimulus volumes as low as 1-2μl. This comprehensive description will allow other investigators to adapt this setup to their own experimental needs and can thus promote our physiological understanding of this fascinating chemosensory system. With minor changes it can also be adapted for other rodent species. Copyright © 2017 Elsevier B.V. All rights reserved.

Discriminative stimulus properties of mitragynine (kratom) in rats.

PubMed

Harun, Norsyifa; Hassan, Zurina; Navaratnam, Visweswaran; Mansor, Sharif M; Shoaib, Mohammed

2015-07-01

Mitragynine (MG) is the primary active alkaloid extracted from the leaves of Mitragyna speciosa or kratom and exhibits pharmacological activities mediated by opioid receptors. The plant has been traditionally used for its opium and psychostimulant-like effects to increase work efficiency or as a substitute in the self-treatment of opiate addiction. The present study was performed to investigate the discriminative stimulus effects of MG in rats. The pharmacological mechanism of MG action and its derivative, 7-hydroxymitragynine (7-HMG) with a specific focus on opioid receptor involvement was examined in rats trained to discriminate morphine from vehicle. In order to study the dual actions of MG, the effect of cocaine substitution to the MG discriminative stimulus was also performed in MG-trained rats. Male Sprague Dawley rats were trained to discriminate MG from vehicle in a two-lever drug discrimination procedure under a tandem variable-interval (VI 60') fixed-ratio (FR 10) schedule of food reinforcement. Rats acquired the MG discrimination (15.0 mg/kg, i.p.) which was similar to the acquisition of morphine discrimination (5.0 mg/kg, i.p.) in another group of rats. MG substituted fully to the morphine discriminative stimulus in a dose-dependent manner, suggesting pharmacological similarities between the two drugs. The administration of 7-HMG derivative in 3.0 mg/kg (i.p.) dose engendered full generalisation to the morphine discriminative stimulus. In addition, the MG stimulus also partially generalised to cocaine (10.0 mg/kg, i.p.) stimulus. The present study demonstrates that the discriminative stimulus effect of MG possesses both opioid- and psychostimulant-like subjective effects.

Emergent conditional relations in a Go/No-Go procedure: figure-ground and stimulus-position compound relations.

PubMed

Debert, Paula; Huziwara, Edson M; Faggiani, Robson Brino; De Mathis, Maria Eugênia Simões; McIlvane, William J

2009-09-01

Past research has demonstrated emergent conditional relations using a go/no-go procedure with pairs of figures displayed side-by-side on a computer screen. The present study sought to extend applications of this procedure. In Experiment 1, we evaluated whether emergent conditional relations could be demonstrated when two-component stimuli were displayed in figure-ground relationships-abstract figures displayed on backgrounds of different colors. Five normally capable adults participated. During training, each two-component stimulus was presented successively. Responses emitted in the presence of some stimulus pairs (A1B1, A2B2, A3B3, B1C1, B2C2 and B3C3) were reinforced, whereas responses emitted in the presence of other pairs (A1B2, A1B3, A2B1, A2B3, A3B1, A3B2, B1C2, B1C3, B2C1, B2C3, B3C1 and B3C2) were not. During tests, new configurations (AC and CA) were presented, thus emulating structurally the matching-to-sample tests employed in typical equivalence studies. All participants showed emergent relations consistent with stimulus equivalence during testing. In Experiment 2, we systematically replicated the procedures with stimulus compounds consisting of four figures (A1, A2, C1 and C2) and two locations (left - B1 and right - B2). All 6 normally capable adults exhibited emergent stimulus-stimulus relations. Together, these experiments show that the go/no-go procedure is a potentially useful alternative for studying emergent conditional relations when matching-to-sample is procedurally cumbersome or impossible to use.

Unilateral visual neglect overcome by cues implicit in stimulus arrays.

PubMed Central

Kartsounis, L D; Warrington, E K

1989-01-01

The case of a man with a right hemisphere lesion and with evidence of left-sided visuospatial neglect is reported. On a variety of verbal and nonverbal tasks his performance was significantly modified by information implicit in stimulus configurations. Neglect deficits were present on tests involving spatially distinct or meaningless stimulus arrays but almost absent when stimuli were continuous or meaningfully integrated. PMID:2592968

Aural, visual, and pictorial stimulus formats in false recall.

PubMed

Beauchamp, Heather M

2002-12-01

The present investigation is an initial simultaneous examination of the influence of three stimulus formats on false memories. Several pilot tests were conducted to develop new category associate stimulus lists. 73 women and 26 men (M age=21.1 yr.) were in one of three conditions: they either heard words, were shown words, or were shown pictures highly related to critical nonpresented items. As expected, recall of critical nonpresented stimuli was significantly greater for aural lists than for visually presented words and pictorial images. These findings demonstrate that the accuracy of memory is influenced by the format of the information encoded.

Integration time for the perception of depth from motion parallax.

PubMed

Nawrot, Mark; Stroyan, Keith

2012-04-15

The perception of depth from relative motion is believed to be a slow process that "builds-up" over a period of observation. However, in the case of motion parallax, the potential accuracy of the depth estimate suffers as the observer translates during the viewing period. Our recent quantitative model for the perception of depth from motion parallax proposes that relative object depth (d) can be determined from retinal image motion (dθ/dt), pursuit eye movement (dα/dt), and fixation distance (f) by the formula: d/f≈dθ/dα. Given the model's dynamics, it is important to know the integration time required by the visual system to recover dα and dθ, and then estimate d. Knowing the minimum integration time reveals the incumbent error in this process. A depth-phase discrimination task was used to determine the time necessary to perceive depth-sign from motion parallax. Observers remained stationary and viewed a briefly translating random-dot motion parallax stimulus. Stimulus duration varied between trials. Fixation on the translating stimulus was monitored and enforced with an eye-tracker. The study found that relative depth discrimination can be performed with presentations as brief as 16.6 ms, with only two stimulus frames providing both retinal image motion and the stimulus window motion for pursuit (mean range=16.6-33.2 ms). This was found for conditions in which, prior to stimulus presentation, the eye was engaged in ongoing pursuit or the eye was stationary. A large high-contrast masking stimulus disrupted depth-discrimination for stimulus presentations less than 70-75 ms in both pursuit and stationary conditions. This interval might be linked to ocular-following response eye-movement latencies. We conclude that neural mechanisms serving depth from motion parallax generate a depth estimate much more quickly than previously believed. We propose that additional sluggishness might be due to the visual system's attempt to determine the maximum dθ/dα ratio for a selection of points on a complicated stimulus. Copyright © 2012 Elsevier Ltd. All rights reserved.

The Effect of Anchors and Training on the Reliability of Voice Quality Ratings for Different Types of Speech Stimuli.

PubMed

Brinca, Lilia; Batista, Ana Paula; Tavares, Ana Inês; Pinto, Patrícia N; Araújo, Lara

2015-11-01

The main objective of the present study was to investigate if the type of voice stimuli-sustained vowel, oral reading, and connected speech-results in good intrarater and interrater agreement/reliability. A short-term panel study was performed. Voice samples from 30 native European Portuguese speakers were used in the present study. The speech materials used were (1) the sustained vowel /a/, (2) oral reading of the European Portuguese version of "The Story of Arthur the Rat," and (3) connected speech. After an extensive training with textual and auditory anchors, the judges were asked to rate the severity of dysphonic voice stimuli using the phonation dimensions G, R, and B from the GRBAS scale. The voice samples were judged 6 months and 1 year after the training. Intrarater agreement and reliability were generally very good for all the phonation dimensions and voice stimuli. The highest interrater reliability was obtained using the oral reading stimulus, particularly for phonation dimensions grade (G) and breathiness (B). Roughness (R) was the voice quality that was the most difficult to evaluate, leading to interrater unreliability in all voice quality ratings. Extensive training using textual and auditory anchors and the use of anchors during the voice evaluations appear to be good methods for auditory-perceptual evaluation of dysphonic voices. The best results of interrater reliability were obtained when the oral reading stimulus was used. Breathiness appears to be a voice quality that is easier to evaluate than roughness. Copyright © 2015 The Voice Foundation. Published by Elsevier Inc. All rights reserved.

Visual Perceptual Echo Reflects Learning of Regularities in Rapid Luminance Sequences.

PubMed

Chang, Acer Y-C; Schwartzman, David J; VanRullen, Rufin; Kanai, Ryota; Seth, Anil K

2017-08-30

A novel neural signature of active visual processing has recently been described in the form of the "perceptual echo", in which the cross-correlation between a sequence of randomly fluctuating luminance values and occipital electrophysiological signals exhibits a long-lasting periodic (∼100 ms cycle) reverberation of the input stimulus (VanRullen and Macdonald, 2012). As yet, however, the mechanisms underlying the perceptual echo and its function remain unknown. Reasoning that natural visual signals often contain temporally predictable, though nonperiodic features, we hypothesized that the perceptual echo may reflect a periodic process associated with regularity learning. To test this hypothesis, we presented subjects with successive repetitions of a rapid nonperiodic luminance sequence, and examined the effects on the perceptual echo, finding that echo amplitude linearly increased with the number of presentations of a given luminance sequence. These data suggest that the perceptual echo reflects a neural signature of regularity learning.Furthermore, when a set of repeated sequences was followed by a sequence with inverted luminance polarities, the echo amplitude decreased to the same level evoked by a novel stimulus sequence. Crucially, when the original stimulus sequence was re-presented, the echo amplitude returned to a level consistent with the number of presentations of this sequence, indicating that the visual system retained sequence-specific information, for many seconds, even in the presence of intervening visual input. Altogether, our results reveal a previously undiscovered regularity learning mechanism within the human visual system, reflected by the perceptual echo. SIGNIFICANCE STATEMENT How the brain encodes and learns fast-changing but nonperiodic visual input remains unknown, even though such visual input characterizes natural scenes. We investigated whether the phenomenon of "perceptual echo" might index such learning. The perceptual echo is a long-lasting reverberation between a rapidly changing visual input and evoked neural activity, apparent in cross-correlations between occipital EEG and stimulus sequences, peaking in the alpha (∼10 Hz) range. We indeed found that perceptual echo is enhanced by repeatedly presenting the same visual sequence, indicating that the human visual system can rapidly and automatically learn regularities embedded within fast-changing dynamic sequences. These results point to a previously undiscovered regularity learning mechanism, operating at a rate defined by the alpha frequency. Copyright © 2017 the authors 0270-6474/17/378486-12$15.00/0.

Non-Instrumental Movement Inhibition (NIMI) Differentially Suppresses Head and Thigh Movements during Screenic Engagement: Dependence on Interaction

PubMed Central

Witchel, Harry J.; Santos, Carlos P.; Ackah, James K.; Westling, Carina E. I.; Chockalingam, Nachiappan

2016-01-01

Background: Estimating engagement levels from postural micromovements has been summarized by some researchers as: increased proximity to the screen is a marker for engagement, while increased postural movement is a signal for disengagement or negative affect. However, these findings are inconclusive: the movement hypothesis challenges other findings of dyadic interaction in humans, and experiments on the positional hypothesis diverge from it. Hypotheses: (1) Under controlled conditions, adding a relevant visual stimulus to an auditory stimulus will preferentially result in Non-Instrumental Movement Inhibition (NIMI) of the head. (2) When instrumental movements are eliminated and computer-interaction rate is held constant, for two identically-structured stimuli, cognitive engagement (i.e., interest) will result in measurable NIMI of the body generally. Methods: Twenty-seven healthy participants were seated in front of a computer monitor and speakers. Discrete 3-min stimuli were presented with interactions mediated via a handheld trackball without any keyboard, to minimize instrumental movements of the participant's body. Music videos and audio-only music were used to test hypothesis (1). Time-sensitive, highly interactive stimuli were used to test hypothesis (2). Subjective responses were assessed via visual analog scales. The computer users' movements were quantified using video motion tracking from the lateral aspect. Repeated measures ANOVAs with Tukey post hoc comparisons were performed. Results: For two equivalently-engaging music videos, eliminating the visual content elicited significantly increased non-instrumental movements of the head (while also decreasing subjective engagement); a highly engaging user-selected piece of favorite music led to further increased non-instrumental movement. For two comparable reading tasks, the more engaging reading significantly inhibited (42%) movement of the head and thigh; however, when a highly engaging video game was compared to the boring reading, even though the reading task and the game had similar levels of interaction (trackball clicks), only thigh movement was significantly inhibited, not head movement. Conclusions: NIMI can be elicited by adding a relevant visual accompaniment to an audio-only stimulus or by making a stimulus cognitively engaging. However, these results presume that all other factors are held constant, because total movement rates can be affected by cognitive engagement, instrumental movements, visual requirements, and the time-sensitivity of the stimulus. PMID:26941666

Non-Instrumental Movement Inhibition (NIMI) Differentially Suppresses Head and Thigh Movements during Screenic Engagement: Dependence on Interaction.

PubMed

Witchel, Harry J; Santos, Carlos P; Ackah, James K; Westling, Carina E I; Chockalingam, Nachiappan

2016-01-01

Estimating engagement levels from postural micromovements has been summarized by some researchers as: increased proximity to the screen is a marker for engagement, while increased postural movement is a signal for disengagement or negative affect. However, these findings are inconclusive: the movement hypothesis challenges other findings of dyadic interaction in humans, and experiments on the positional hypothesis diverge from it. (1) Under controlled conditions, adding a relevant visual stimulus to an auditory stimulus will preferentially result in Non-Instrumental Movement Inhibition (NIMI) of the head. (2) When instrumental movements are eliminated and computer-interaction rate is held constant, for two identically-structured stimuli, cognitive engagement (i.e., interest) will result in measurable NIMI of the body generally. Twenty-seven healthy participants were seated in front of a computer monitor and speakers. Discrete 3-min stimuli were presented with interactions mediated via a handheld trackball without any keyboard, to minimize instrumental movements of the participant's body. Music videos and audio-only music were used to test hypothesis (1). Time-sensitive, highly interactive stimuli were used to test hypothesis (2). Subjective responses were assessed via visual analog scales. The computer users' movements were quantified using video motion tracking from the lateral aspect. Repeated measures ANOVAs with Tukey post hoc comparisons were performed. For two equivalently-engaging music videos, eliminating the visual content elicited significantly increased non-instrumental movements of the head (while also decreasing subjective engagement); a highly engaging user-selected piece of favorite music led to further increased non-instrumental movement. For two comparable reading tasks, the more engaging reading significantly inhibited (42%) movement of the head and thigh; however, when a highly engaging video game was compared to the boring reading, even though the reading task and the game had similar levels of interaction (trackball clicks), only thigh movement was significantly inhibited, not head movement. NIMI can be elicited by adding a relevant visual accompaniment to an audio-only stimulus or by making a stimulus cognitively engaging. However, these results presume that all other factors are held constant, because total movement rates can be affected by cognitive engagement, instrumental movements, visual requirements, and the time-sensitivity of the stimulus.

The effects of click and tone-burst stimulus parameters on the vestibular evoked myogenic potential (VEMP).

PubMed

Akin, Faith Wurm; Murnane, Owen D; Proffitt, Tina M

2003-11-01

Vestibular evoked myogenic potentials (VEMP) are short latency electromyograms (EMG) evoked by high-level acoustic stimuli and recorded from surface electrodes over the tonically contracted sternocleidomastoid (SCM) muscle and are presumed to originate in the saccule. The present experiments examined the effects of click and tone-burst level and stimulus frequency on the latency, amplitude, and threshold of the VEMP in subjects with normal hearing sensitivity and no history of vestibular disease. VEMPs were recorded in all subjects using 100 dB nHL click stimuli. Most subjects had VEMPs present at 500, 750, and 1000 Hz, and few subjects had VEMPs present at 2000 Hz. The response amplitude of the VEMP increased with click and tone-burst level, whereas VEMP latency was not influenced by the stimulus level. The largest tone-burst-evoked VEMPs and lowest thresholds were obtained at 500 and 750 Hz. VEMP latency was independent of stimulus frequency when tone-burst duration was held constant.

The Effect of Pupils' Race, Class, Test Scores, and Classroom Behavior on the Academic Expectancies of Southern and Non-Southern White Teachers.

ERIC Educational Resources Information Center

Long, Barbara H.; Henderson, Edmund H.

This investigation of the causal dynamics of teacher expectancies is carried out in an artificial setting, making use of contrived stimulus children. Characteristics of stimulus persons were varied in a 2 by 2 factorial design. Pupil characteristics included race (black or white) and class (lower or middle). Different groups of subjects rated each…

The contribution of α4β2 and non-α4β2 nicotinic acetylcholine receptors to the discriminative stimulus effects of nicotine and varenicline in mice.

PubMed

de Moura, Fernando B; McMahon, Lance R

2017-03-01

The extent to which non-α4β2 versus α4β2* nAChRs contribute to the behavioral effects of varenicline and other nAChR agonists is unclear. The purpose of this study was to characterize the discriminative stimulus effects of varenicline and nicotine using various nAChR agonists and antagonists to elucidate possible non-α4β2 nAChR mechanisms. Separate groups of male C57BL/6J mice were trained to discriminate varenicline (3.2 mg/kg) or nicotine (1 mg/kg). Test drugs included mecamylamine; the nAChR agonists epibatidine, nicotine, cytisine, varenicline, and RTI-102; the β2-containing nAChR antagonist dihydro-β-erythroidine (DHβE); the α7 nAChR agonist PNU-282987; the α7 antagonist methyllycaconitine (MLA); the α3β4 antagonist 18-methoxycoronaridine (18-MC); and the non-nAChR drugs midazolam and cocaine. In nicotine-trained mice, maximum nicotine-appropriate responding was 95% nicotine, 94% epibatidine, 63% varenicline, 58% cytisine, and less than 50% for RTI-102, PNU-282987, midazolam, and cocaine. In varenicline-trained mice, maximum varenicline-appropriate responding was 90% varenicline, 86% epibatidine, 74% cytisine, 80% RTI-102, 50% cocaine, and 50% or less for nicotine, PNU-282987, and midazolam. Drugs were studied to doses that abolished operant responding. Mecamylamine antagonized the discriminative stimulus effects, but not the rate-decreasing effects, of nicotine and varenicline. DHβE antagonized the discriminative stimulus and rate-decreasing effects of nicotine but not varenicline in either the nicotine or varenicline discrimination assays. The discriminative stimulus, but not the rate-decreasing, effects of epibatidine were antagonized by DHβE regardless of the training drug. These results suggest that α4β2* nAChRs differentially mediate the discriminative stimulus effects of nicotine and varenicline, and suggest that varenicline has substantial non-α4β2 nAChR activity.

The Behavioral Relevance of Cortical Neural Ensemble Responses Emerges Suddenly

PubMed Central

Sadacca, Brian F.; Mukherjee, Narendra; Vladusich, Tony; Li, Jennifer X.

2016-01-01

Whereas many laboratory-studied decisions involve a highly trained animal identifying an ambiguous stimulus, many naturalistic decisions do not. Consumption decisions, for instance, involve determining whether to eject or consume an already identified stimulus in the mouth and are decisions that can be made without training. By standard analyses, rodent cortical single-neuron taste responses come to predict such consumption decisions across the 500 ms preceding the consumption or rejection itself; decision-related firing emerges well after stimulus identification. Analyzing single-trial ensemble activity using hidden Markov models, we show these decision-related cortical responses to be part of a reliable sequence of states (each defined by the firing rates within the ensemble) separated by brief state-to-state transitions, the latencies of which vary widely between trials. When we aligned data to the onset of the (late-appearing) state that dominates during the time period in which single-neuron firing is correlated to taste palatability, the apparent ramp in stimulus-aligned choice-related firing was shown to be a much more precipitous coherent jump. This jump in choice-related firing resembled a step function more than it did the output of a standard (ramping) decision-making model, and provided a robust prediction of decision latency in single trials. Together, these results demonstrate that activity related to naturalistic consumption decisions emerges nearly instantaneously in cortical ensembles. SIGNIFICANCE STATEMENT This paper provides a description of how the brain makes evaluative decisions. The majority of work on the neurobiology of decision making deals with “what is it?” decisions; out of this work has emerged a model whereby neurons accumulate information about the stimulus in the form of slowly increasing firing rates and reach a decision when those firing rates reach a threshold. Here, we study a different kind of more naturalistic decision—a decision to evaluate “what shall I do with it?” after the identity of a taste in the mouth has been identified—and show that this decision is not made through the gradual increasing of stimulus-related firing, but rather that this decision appears to be made in a sudden moment of “insight.” PMID:26791199

Physiological reactivity of pregnant women to evoked fetal startle

PubMed Central

DiPietro, Janet A.; Voegtline, Kristin M.; Costigan, Kathleen A.; Aguirre, Frank; Kivlighan, Katie; Chen, Ping

2013-01-01

Objective The bidirectional nature of mother-child interaction is widely acknowledged during infancy and childhood. Prevailing models during pregnancy focus on unidirectional influences exerted by the pregnant woman on the developing fetus. Prior work has indicated that the fetus also affects the pregnant woman. Our objective was to determine whether a maternal psychophysiological response to stimulation of the fetus could be isolated. Methods Using a longitudinal design, an airborne auditory stimulus was used to elicit a fetal heart rate and motor response at 24 (n = 47) and 36 weeks (n = 45) gestation. Women were blind to condition (stimulus versus sham). Maternal parameters included cardiac (heart rate) and electrodermal (skin conductance) responses. Multilevel modeling of repeated measures with 5 data points per second was used to examine fetal and maternal responses. Results As expected, compared to a sham condition, the stimulus generated a fetal motor response at both gestational ages, consistent with a mild fetal startle. Fetal stimulation was associated with significant, transient slowing of maternal heart rate coupled with increased skin conductance within 10 s of the stimulus at both gestational ages. Nulliparous women showed greater electrodermal responsiveness. The magnitude of the fetal motor response significantly corresponded to the maternal skin conductance response at 5, 10, 15, and 30 s following stimulation. Conclusion Elicited fetal movement exerts an independent influence on the maternal autonomic nervous system. This finding contributes to current models of the dyadic relationship during pregnancy between fetus and pregnant woman. PMID:24119937

Pyff - a pythonic framework for feedback applications and stimulus presentation in neuroscience.

PubMed

Venthur, Bastian; Scholler, Simon; Williamson, John; Dähne, Sven; Treder, Matthias S; Kramarek, Maria T; Müller, Klaus-Robert; Blankertz, Benjamin

2010-01-01

This paper introduces Pyff, the Pythonic feedback framework for feedback applications and stimulus presentation. Pyff provides a platform-independent framework that allows users to develop and run neuroscientific experiments in the programming language Python. Existing solutions have mostly been implemented in C++, which makes for a rather tedious programming task for non-computer-scientists, or in Matlab, which is not well suited for more advanced visual or auditory applications. Pyff was designed to make experimental paradigms (i.e., feedback and stimulus applications) easily programmable. It includes base classes for various types of common feedbacks and stimuli as well as useful libraries for external hardware such as eyetrackers. Pyff is also equipped with a steadily growing set of ready-to-use feedbacks and stimuli. It can be used as a standalone application, for instance providing stimulus presentation in psychophysics experiments, or within a closed loop such as in biofeedback or brain-computer interfacing experiments. Pyff communicates with other systems via a standardized communication protocol and is therefore suitable to be used with any system that may be adapted to send its data in the specified format. Having such a general, open-source framework will help foster a fruitful exchange of experimental paradigms between research groups. In particular, it will decrease the need of reprogramming standard paradigms, ease the reproducibility of published results, and naturally entail some standardization of stimulus presentation.

Categorical information influences conscious perception: An interaction between object-substitution masking and repetition blindness.

PubMed

Goodhew, Stephanie C; Greenwood, John A; Edwards, Mark

2016-05-01

The visual system is constantly bombarded with dynamic input. In this context, the creation of enduring object representations presents a particular challenge. We used object-substitution masking (OSM) as a tool to probe these processes. In particular, we examined the effect of target-like stimulus repetitions on OSM. In visual crowding, the presentation of a physically identical stimulus to the target reduces crowding and improves target perception, whereas in spatial repetition blindness, the presentation of a stimulus that belongs to the same category (type) as the target impairs perception. Across two experiments, we found an interaction between spatial repetition blindness and OSM, such that repeating a same-type stimulus as the target increased masking magnitude relative to presentation of a different-type stimulus. These results are discussed in the context of the formation of object files. Moreover, the fact that the inducer only had to belong to the same "type" as the target in order to exacerbate masking, without necessarily being physically identical to the target, has important implications for our understanding of OSM per se. That is, our results show the target is processed to a categorical level in OSM despite effective masking and, strikingly, demonstrate that this category-level content directly influences whether or not the target is perceived, not just performance on another task (as in priming).

Pyff – A Pythonic Framework for Feedback Applications and Stimulus Presentation in Neuroscience

PubMed Central

Venthur, Bastian; Scholler, Simon; Williamson, John; Dähne, Sven; Treder, Matthias S.; Kramarek, Maria T.; Müller, Klaus-Robert; Blankertz, Benjamin

2010-01-01

This paper introduces Pyff, the Pythonic feedback framework for feedback applications and stimulus presentation. Pyff provides a platform-independent framework that allows users to develop and run neuroscientific experiments in the programming language Python. Existing solutions have mostly been implemented in C++, which makes for a rather tedious programming task for non-computer-scientists, or in Matlab, which is not well suited for more advanced visual or auditory applications. Pyff was designed to make experimental paradigms (i.e., feedback and stimulus applications) easily programmable. It includes base classes for various types of common feedbacks and stimuli as well as useful libraries for external hardware such as eyetrackers. Pyff is also equipped with a steadily growing set of ready-to-use feedbacks and stimuli. It can be used as a standalone application, for instance providing stimulus presentation in psychophysics experiments, or within a closed loop such as in biofeedback or brain–computer interfacing experiments. Pyff communicates with other systems via a standardized communication protocol and is therefore suitable to be used with any system that may be adapted to send its data in the specified format. Having such a general, open-source framework will help foster a fruitful exchange of experimental paradigms between research groups. In particular, it will decrease the need of reprogramming standard paradigms, ease the reproducibility of published results, and naturally entail some standardization of stimulus presentation. PMID:21160550

Auditory memory in monkeys: costs and benefits of proactive interference.

PubMed

Bigelow, James; Poremba, Amy

2013-05-01

Proactive interference (PI) has traditionally been understood as an adverse consequence of stimulus repetition during memory tasks. Herein, we present data that emphasize costs as well as benefits of PI for monkeys performing an auditory delayed matching-to-sample (DMTS) task. The animals made same/different judgments for a variety of simple and complex sounds separated by a 5-s memory delay. Each session used a stimulus set that included eight sounds; thus, each sound was repeated multiple times per session for match trials and for nonmatch trials as the sample (Cue 1) or test (Cue 2) stimulus. For nonmatch trials, performance was substantially diminished when the test stimulus had been previously presented on a recent trial. However, when the sample stimulus had been recently presented, performance was significantly improved. We also observed a marginal performance benefit when stimuli for match trials had been recently presented. The costs of PI for nonmatch test stimuli were greater than the combined benefits of PI for nonmatch sample stimuli and match trials, indicating that the net influence of PI is detrimental. For all three manifestations of PI, the effects are shown to extend beyond the immediately subsequent trial. Our data suggest that PI in auditory DMTS is best understood as an enduring influence that can be both detrimental and beneficial to memory-task performance. © 2012 Wiley Periodicals, Inc.

Autoshaping Chicks with Heat Reinforcement: The Role of Stimulus-Reinforcer and Response-Reinforcer Relations

ERIC Educational Resources Information Center

Wasserman, Edward A.; And Others

1975-01-01

The present series of experiments attempted to analyze more fully the contributions of stimulus-reinforcer and response-reinforcer relations to autoshaping within a single conditioning situation. (Author)

Episodic memory for spatial context biases spatial attention.

PubMed

Ciaramelli, Elisa; Lin, Olivia; Moscovitch, Morris

2009-01-01

The study explores the bottom-up attentional consequences of episodic memory retrieval. Individuals studied words (Experiment 1) or pictures (Experiment 2) presented on the left or on the right of the screen. They then viewed studied and new stimuli in the centre of the screen. One-second after the appearance of each stimulus, participants had to respond to a dot presented on the left or on the right of the screen. The dot could follow a stimulus that had been presented, during the study phase, on the same side as the dot (congruent condition), a stimulus that had been presented on the opposite side (incongruent condition), or a new stimulus (neutral condition). Subjects were faster to respond to the dot in the congruent compared to the incongruent condition, with an overall right visual field advantage in Experiment 1. The memory-driven facilitation effect correlated with subjects' re-experiencing of the encoding context (R responses; Experiment 1), but not with their explicit memory for the side of items' presentation (source memory; Experiment 2). The results indicate that memory contents are attended automatically and can bias the deployment of attention. The degree to which memory and attention interact appears related to subjective but not objective indicators of memory strength.

Effects of background stimulation upon eye-movement information.

PubMed

Nakamura, S

1996-04-01

To investigate the effects of background stimulation upon eye-movement information (EMI), the perceived deceleration of the target motion during pursuit eye movement (Aubert-Fleishl paradox) was analyzed. In the experiment, a striped pattern was used as a background stimulus with various brightness contrasts and spatial frequencies for serially manipulating the attributions of the background stimulus. Analysis showed that the retinal-image motion of the background stimulus (optic flow) affected eye-movement information and that the effects of optic flow became stronger when high contrast and low spatial frequency stripes were presented as the background stimulus. In conclusion, optic flow is one source of eye-movement information in determining real object motion, and the effectiveness of optic flow depends on the attributes of the background stimulus.

Neural priming in human frontal cortex: multiple forms of learning reduce demands on the prefrontal executive system.

PubMed

Race, Elizabeth A; Shanker, Shanti; Wagner, Anthony D

2009-09-01

Past experience is hypothesized to reduce computational demands in PFC by providing bottom-up predictive information that informs subsequent stimulus-action mapping. The present fMRI study measured cortical activity reductions ("neural priming"/"repetition suppression") during repeated stimulus classification to investigate the mechanisms through which learning from the past decreases demands on the prefrontal executive system. Manipulation of learning at three levels of representation-stimulus, decision, and response-revealed dissociable neural priming effects in distinct frontotemporal regions, supporting a multiprocess model of neural priming. Critically, three distinct patterns of neural priming were identified in lateral frontal cortex, indicating that frontal computational demands are reduced by three forms of learning: (a) cortical tuning of stimulus-specific representations, (b) retrieval of learned stimulus-decision mappings, and (c) retrieval of learned stimulus-response mappings. The topographic distribution of these neural priming effects suggests a rostrocaudal organization of executive function in lateral frontal cortex.

Revisiting the rise and fall of false recall: presentation rate effects depend on retention interval.

PubMed

Smith, Troy A; Kimball, Daniel R

2012-01-01

Leading theories of false memory predict that veridical and false recall of lists of semantically associated words can be dissociated by varying the presentation speed during study. Specifically, as presentation rate increases from milliseconds to seconds, veridical recall is predicted to increase monotonically while false recall is predicted to show a rapid rise and then a slow decrease--a pattern shown by McDermott and Watson (2001) in a study using immediate recall tests. In three experiments we tested the generality of the effects of rapid presentation rates on veridical and false memory. In Experiments 1 and 2 participants exhibited high levels of false recall on a delayed recall test, even for very fast stimulus onset asynchronies (SOA)--contrary to predictions from leading theories of false memory. When we switched to an immediate recall test in Experiment 3 we replicated the pattern predicted by the theories and observed by McDermott and Watson. Follow-up analyses further showed that the relative output position of false recalls is not affected by presentation rate, contrary to predictions from fuzzy trace theory. Implications for theories of false memory, including activation monitoring theory and fuzzy trace theory, are discussed.

Why rate when you could compare? Using the “EloChoice” package to assess pairwise comparisons of perceived physical strength

PubMed Central

Howard, Kate L.; Woods, Andy T.; Penton-Voak, Ian S.; Neumann, Christof

2018-01-01

We introduce “EloChoice”, a package for R which uses Elo rating to assess pairwise comparisons between stimuli in order to measure perceived stimulus characteristics. To demonstrate the package and compare results from forced choice pairwise comparisons to those from more standard single stimulus rating tasks using Likert (or Likert-type) items, we investigated perceptions of physical strength from images of male bodies. The stimulus set comprised images of 82 men standing on a raised platform with minimal clothing. Strength-related anthropometrics and grip strength measurements were available for each man in the set. UK laboratory participants (Study 1) and US online participants (Study 2) viewed all images in both a Likert rating task, to collect mean Likert scores, and a pairwise comparison task, to calculate Elo, mean Elo (mElo), and Bradley-Terry scores. Within both studies, Likert, Elo and Bradley-Terry scores were closely correlated to mElo scores (all rs > 0.95), and all measures were correlated with stimulus grip strength (all rs > 0.38) and body size (all rs > 0.59). However, mElo scores were less variable than Elo scores and were hundreds of times quicker to compute than Bradley-Terry scores. Responses in pairwise comparison trials were 2/3 quicker than in Likert tasks, indicating that participants found pairwise comparisons to be easier. In addition, mElo scores generated from a data set with half the participants randomly excluded produced very comparable results to those produced with Likert scores from the full participant set, indicating that researchers require fewer participants when using pairwise comparisons. PMID:29293615

Auditory cortical neurons are sensitive to static and continuously changing interaural phase cues.

PubMed

Reale, R A; Brugge, J F

1990-10-01

1. The interaural-phase-difference (IPD) sensitivity of single neurons in the primary auditory (AI) cortex of the anesthetized cat was studied at stimulus frequencies ranging from 120 to 2,500 Hz. Best frequencies of the 43 AI cells sensitive to IPD ranged from 190 to 2,400 Hz. 2. A static IPD was produced when a pair of low-frequency tone bursts, differing from one another only in starting phase, were presented dichotically. The resulting IPD-sensitivity curves, which plot the number of discharges evoked by the binaural signal as a function of IPD, were deeply modulated circular functions. IPD functions were analyzed for their mean vector length (r) and mean interaural phase (phi). Phase sensitivity was relatively independent of best frequency (BF) but highly dependent on stimulus frequency. Regardless of BF or stimulus frequency within the excitatory response area the majority of cells fired maximally when the ipsilateral tone lagged the contralateral signal and fired least when this interaural-phase relationship was reversed. 3. Sensitivity to continuously changing IPD was studied by delivering to the two ears 3-s tones that differed slightly in frequency, resulting in a binaural beat. Approximately 26% of the cells that showed a sensitivity to static changes in IPD also showed a sensitivity to dynamically changing IPD created by this binaural tonal combination. The discharges were highly periodic and tightly synchronized to a particular phase of the binaural beat cycle. High synchrony can be attributed to the fact that cortical neurons typically respond to an excitatory stimulus with but a single spike that is often precisely timed to stimulus onset. A period histogram, binned on the binaural beat frequency (fb), produced an equivalent IPD-sensitivity function for dynamically changing interaural phase. For neurons sensitive to both static and continuously changing interaural phase there was good correspondence between their static (phi s) and dynamic (phi d) mean interaural phases. 4. All cells responding to a dynamically changing stimulus exhibited a linear relationship between mean interaural phase and beat frequency. Most cells responded equally well to binaural beats regardless of the initial direction of phase change. For a fixed duration stimulus, and at relatively low fb, the number of spikes evoked increased with increasing fb, reflecting the increasing number of effective stimulus cycles. At higher fb, AI neurons were unable to follow the rate at which the most effective phase repeated itself during the 3 s of stimulation.(ABSTRACT TRUNCATED AT 400 WORDS)

The Influence of State Anxiety on Fear Discrimination and Extinction in Females

PubMed Central

Dibbets, Pauline; Evers, Elisabeth A. T.

2017-01-01

Formal theories have linked pathological anxiety to a failure in fear response inhibition. Previously, we showed that aberrant response inhibition is not restricted to anxiety patients, but can also be observed in anxiety-prone adults. However, less is known about the influence of currently experienced levels of anxiety on inhibitory learning. The topic is highly important as state anxiety has a debilitating effect on cognition, emotion, and physiology and is linked to several anxiety disorders. In the present study, healthy female volunteers performed a fear conditioning task, after being informed that they will have to perform the Trier Social Stress Test task (n = 25; experimental group) or a control task (n = 25; control group) upon completion of the conditioning task. The results showed that higher levels of state anxiety corresponded with a reduced discrimination between a stimulus (CS+) typically followed by an aversive event and a stimulus (CS-) that is never followed by an aversive event both during the acquisition and the extinction phase. No effect of state anxiety on the skin conductance response associated with CS+ and CS- was found. Additionally, higher levels of state anxiety coincided with more negative valence ratings of the CSs. The results suggest that increased stress-induced state anxiety might lead to stimulus generalization during fear acquisition, thereby impairing associative learning. PMID:28360869

Behavioral pattern separation and its link to the neural mechanisms of fear generalization.

PubMed

Lange, Iris; Goossens, Liesbet; Michielse, Stijn; Bakker, Jindra; Lissek, Shmuel; Papalini, Silvia; Verhagen, Simone; Leibold, Nicole; Marcelis, Machteld; Wichers, Marieke; Lieverse, Ritsaert; van Os, Jim; van Amelsvoort, Therese; Schruers, Koen

2017-11-01

Fear generalization is a prominent feature of anxiety disorders and post-traumatic stress disorder (PTSD). It is defined as enhanced fear responding to a stimulus that bears similarities, but is not identical to a threatening stimulus. Pattern separation, a hippocampal-dependent process, is critical for stimulus discrimination; it transforms similar experiences or events into non-overlapping representations. This study is the first in humans to investigate the extent to which fear generalization relies on behavioral pattern separation abilities. Participants (N = 46) completed a behavioral task taxing pattern separation, and a neuroimaging fear conditioning and generalization paradigm. Results show an association between lower behavioral pattern separation performance and increased generalization in shock expectancy scores, but not in fear ratings. Furthermore, lower behavioral pattern separation was associated with diminished recruitment of the subcallosal cortex during presentation of generalization stimuli. This region showed functional connectivity with the orbitofrontal cortex and ventromedial prefrontal cortex. Together, the data provide novel experimental evidence that pattern separation is related to generalization of threat expectancies, and reduced fear inhibition processes in frontal regions. Deficient pattern separation may be critical in overgeneralization and therefore may contribute to the pathophysiology of anxiety disorders and PTSD. © The Author (2017). Published by Oxford University Press.

The absolute threshold of cone vision

PubMed Central

Koeing, Darran; Hofer, Heidi

2013-01-01

We report measurements of the absolute threshold of cone vision, which has been previously underestimated due to sub-optimal conditions or overly strict subjective response criteria. We avoided these limitations by using optimized stimuli and experimental conditions while having subjects respond within a rating scale framework. Small (1′ fwhm), brief (34 msec), monochromatic (550 nm) stimuli were foveally presented at multiple intensities in dark-adapted retina for 5 subjects. For comparison, 4 subjects underwent similar testing with rod-optimized stimuli. Cone absolute threshold, that is, the minimum light energy for which subjects were just able to detect a visual stimulus with any response criterion, was 203 ± 38 photons at the cornea, ∼0.47 log units lower than previously reported. Two-alternative forced-choice measurements in a subset of subjects yielded consistent results. Cone thresholds were less responsive to criterion changes than rod thresholds, suggesting a limit to the stimulus information recoverable from the cone mosaic in addition to the limit imposed by Poisson noise. Results were consistent with expectations for detection in the face of stimulus uncertainty. We discuss implications of these findings for modeling the first stages of human cone vision and interpreting psychophysical data acquired with adaptive optics at the spatial scale of the receptor mosaic. PMID:21270115

Stimulus similarity determines the prevalence of behavioral laterality in a visual discrimination task for mice

PubMed Central

Treviño, Mario

2014-01-01

Animal choices depend on direct sensory information, but also on the dynamic changes in the magnitude of reward. In visual discrimination tasks, the emergence of lateral biases in the choice record from animals is often described as a behavioral artifact, because these are highly correlated with error rates affecting psychophysical measurements. Here, we hypothesized that biased choices could constitute a robust behavioral strategy to solve discrimination tasks of graded difficulty. We trained mice to swim in a two-alterative visual discrimination task with escape from water as the reward. Their prevalence of making lateral choices increased with stimulus similarity and was present in conditions of high discriminability. While lateralization occurred at the individual level, it was absent, on average, at the population level. Biased choice sequences obeyed the generalized matching law and increased task efficiency when stimulus similarity was high. A mathematical analysis revealed that strongly-biased mice used information from past rewards but not past choices to make their current choices. We also found that the amount of lateralized choices made during the first day of training predicted individual differences in the average learning behavior. This framework provides useful analysis tools to study individualized visual-learning trajectories in mice. PMID:25524257

Possible influences on color constancy by motion of color targets and by attention-controlled gaze.

PubMed

Wan, Lifang; Shinomori, Keizo

2018-04-01

We investigated the influence of motion on color constancy using a chromatic stimulus presented in various conditions (static, motion, and rotation). Attention to the stimulus and background was also controlled in different gaze modes, constant fixation of the stimulus, and random viewing of the stimulus. Color constancy was examined in six young observers using a haploscopic view of a computer monitor. The target and background were illuminated in simulation by red, green, blue, and yellow, shifted from daylight (D65) by specific color differences along L - M or S - (L + M) axes on the equiluminance plane. The standard pattern (under D65) and test pattern (under the color illuminant) of a 5-deg square were presented side by side, consisting of 1.2-deg square targets with one of 12 colors at each center, surrounded by 230 background ellipses consisting of eight other colors. The central color targets in both patterns flipped between top and bottom locations at the rate of 3 deg/s in the motion condition. The results indicated an average reduction of color constancy over the 12 test colors by motion. The random viewing parameter indicated better color constancy by more attention to the background, although the difference was not significant. Color constancy of the four color illuminations was better to worse in green, red, yellow, and blue, respectively. The reduction of color constancy by motion could be explained by less contribution of the illumination estimation effect on color constancy. In the motion with constant fixation condition, the retina strongly adapted to the mean chromaticity of the background. However, motion resulted in less attention to the color of the background, causing a weaker effect of the illumination estimation. Conversely, in the static state with a random viewing condition, more attention to the background colors caused a stronger illumination estimation effect, and color constancy was improved overall.

Predictive Physiological Anticipation Preceding Seemingly Unpredictable Stimuli: A Meta-Analysis

PubMed Central

Mossbridge, Julia; Tressoldi, Patrizio; Utts, Jessica

2012-01-01

This meta-analysis of 26 reports published between 1978 and 2010 tests an unusual hypothesis: for stimuli of two or more types that are presented in an order designed to be unpredictable and that produce different post-stimulus physiological activity, the direction of pre-stimulus physiological activity reflects the direction of post-stimulus physiological activity, resulting in an unexplained anticipatory effect. The reports we examined used one of two paradigms: (1) randomly ordered presentations of arousing vs. neutral stimuli, or (2) guessing tasks with feedback (correct vs. incorrect). Dependent variables included: electrodermal activity, heart rate, blood volume, pupil dilation, electroencephalographic activity, and blood oxygenation level dependent (BOLD) activity. To avoid including data hand-picked from multiple different analyses, no post hoc experiments were considered. The results reveal a significant overall effect with a small effect size [fixed effect: overall ES = 0.21, 95% CI = 0.15–0.27, z = 6.9, p < 2.7 × 10−12; random effects: overall (weighted) ES = 0.21, 95% CI = 0.13–0.29, z = 5.3, p < 5.7 × 10−8]. Higher quality experiments produced a quantitatively larger effect size and a greater level of significance than lower quality studies. The number of contrary unpublished reports that would be necessary to reduce the level of significance to chance (p > 0.05) was conservatively calculated to be 87 reports. We explore alternative explanations and examine the potential linkage between this unexplained anticipatory activity and other results demonstrating meaningful pre-stimulus activity preceding behaviorally relevant events. We conclude that to further examine this currently unexplained anticipatory activity, multiple replications arising from different laboratories using the same methods are necessary. The cause of this anticipatory activity, which undoubtedly lies within the realm of natural physical processes (as opposed to supernatural or paranormal ones), remains to be determined. PMID:23109927

Resistance to change and frequency of response-dependent stimuli uncorrelated with reinforcement.

PubMed

Podlesnik, Christopher A; Jimenez-Gomez, Corina; Ward, Ryan D; Shahan, Timothy A

2009-09-01

Stimuli uncorrelated with reinforcement have been shown to enhance response rates and resistance to disruption; however, the effects of different rates of stimulus presentations have not been assessed. In two experiments, we assessed the effects of adding different rates of response-dependent brief stimuli uncorrelated with primary reinforcement on relative response rates and resistance to change. In both experiments, pigeons responded on variable-interval 60-s schedules of food reinforcement in two components of a multiple schedule, and brief response-dependent keylight-color changes were added to one or both components. Although relative response rates were not systematically affected in either experiment, relative resistance to presession feeding and extinction were. In Experiment 1, adding stimuli on a variable-interval schedule to one component of a multiple schedule either at a low rate (1 per min) for one group or at a high rate (4 per min) for another group similarly increased resistance to disruption in the components with added stimuli. When high and low rates of stimuli were presented across components (i.e., within subjects) in Experiment 2, however, relative resistance to disruption was greater in the component presenting stimuli at a lower rate. These results suggest that stimuli uncorrelated with food reinforcement do not strengthen responding in the same way as primary reinforcers.

Infant Development in Father-Absent Families.

ERIC Educational Resources Information Center

Pedersen, Frank A.; And Others

1979-01-01

Father role in infancy was examined through a comparison of the stimulus responses of 27 infants reared by their mothers in single-parent families with the stimulus responses of 28 infants in father-present families. (CM)

Prediction of truly random future events using analysis of prestimulus electroencephalographic data

NASA Astrophysics Data System (ADS)

Baumgart, Stephen L.; Franklin, Michael S.; Jimbo, Hiroumi K.; Su, Sharon J.; Schooler, Jonathan

2017-05-01

Our hypothesis is that pre-stimulus physiological data can be used to predict truly random events tied to perceptual stimuli (e.g., lights and sounds). Our experiment presents light and sound stimuli to a passive human subject while recording electrocortical potentials using a 32-channel Electroencephalography (EEG) system. For every trial a quantum random number generator (qRNG) chooses from three possible selections with equal probability: a light stimulus, a sound stimulus, and no stimulus. Time epochs are defined preceding and post-ceding each stimulus for which mean average potentials were computed across all trials for the three possible stimulus types. Data from three regions of the brain are examined. In all three regions mean potential for light stimuli was generally enhanced relative to baseline during the period starting approximately 2 seconds before the stimulus. For sound stimuli, mean potential decreased relative to baseline during the period starting approximately 2 seconds before the stimulus. These changes from baseline may indicated the presence of evoked potentials arising from the stimulus. A P200 peak was observed in data recorded from frontal electrodes. The P200 is a well-known potential arising from the brain's processing of visual stimuli and its presence represents a replication of a known neurological phenomenon.

Memorable Audiovisual Narratives Synchronize Sensory and Supramodal Neural Responses

PubMed Central

2016-01-01

Abstract Our brains integrate information across sensory modalities to generate perceptual experiences and form memories. However, it is difficult to determine the conditions under which multisensory stimulation will benefit or hinder the retrieval of everyday experiences. We hypothesized that the determining factor is the reliability of information processing during stimulus presentation, which can be measured through intersubject correlation of stimulus-evoked activity. We therefore presented biographical auditory narratives and visual animations to 72 human subjects visually, auditorily, or combined, while neural activity was recorded using electroencephalography. Memory for the narrated information, contained in the auditory stream, was tested 3 weeks later. While the visual stimulus alone led to no meaningful retrieval, this related stimulus improved memory when it was combined with the story, even when it was temporally incongruent with the audio. Further, individuals with better subsequent memory elicited neural responses during encoding that were more correlated with their peers. Surprisingly, portions of this predictive synchronized activity were present regardless of the sensory modality of the stimulus. These data suggest that the strength of sensory and supramodal activity is predictive of memory performance after 3 weeks, and that neural synchrony may explain the mnemonic benefit of the functionally uninformative visual context observed for these real-world stimuli. PMID:27844062

The effects of social rearing on preferences formed during filial imprinting and their neural correlates.

PubMed

Town, Stephen Michael

2011-08-01

Filial imprinting was originally proposed to be an irreversible process by which a young animal forms a preference for an object experienced early in life. The present study examined the effects of experience after imprinting on the stability of preferences of domestic chicks (Gallus gallus domesticus) for an imprinting stimulus by rearing imprinted chicks socially or in isolation. Chicks reared socially or in isolation retained preferences for the imprinting stimulus; however, social rearing weakened the strength of preferences. The responses of neurons within the intermediate and medial mesopallium--a forebrain region necessary for imprinting were also recorded in socially reared and isolated chicks when presented with the visual component of the imprinting stimulus and novel object. Consistent with existing findings, neurons recorded from isolated chicks responded more strongly to the imprinting stimulus than novel object. However, social rearing diminished the disparity between responses to stimuli such that neurons recorded from socially reared chicks responded similarly to the imprinting stimulus and novel object. These findings suggest that social rearing may impair the retention of preferences formed during imprinting through mechanisms involving the IMM.

Assessment and Treatment of Selective Mutism: Recommendations and a Case Study.

ERIC Educational Resources Information Center

Sheridan, Susan M.; And Others

1995-01-01

Presents results of stimulus fading procedure used to treat a six-year-old girl with elective mutism. Presents assessment protocol that features procedures that can be used to render a diagnosis and assist in treatment planning. Results suggest stimulus fading of new persons into the school setting was effective in producing speech. (JBJ)

The Development of Pointing Perception in Infancy: Effects of Communicative Signals on Covert Shifts of Attention

ERIC Educational Resources Information Center

Daum, Moritz M.; Ulber, Julia; Gredebäck, Gustaf

2013-01-01

The present study aims to investigate the interplay of verbal and nonverbal communication with respect to infants' perception of pointing gestures. Infants were presented with still images of pointing hands (cue) in combination with an acoustic stimulus. The communicative content of this acoustic stimulus was varied from being human and…

A method for simultaneously counterbalancing condition order and assignment of stimulus materials to conditions.

PubMed

Zeelenberg, René; Pecher, Diane

2015-03-01

Counterbalanced designs are frequently used in the behavioral sciences. Studies often counterbalance either the order in which conditions are presented in the experiment or the assignment of stimulus materials to conditions. Occasionally, researchers need to simultaneously counterbalance both condition order and stimulus assignment to conditions. Lewis (1989; Behavior Research Methods, Instruments, & Computers 25:414-415, 1993) presented a method for constructing Latin squares that fulfill these requirements. The resulting Latin squares counterbalance immediate sequential effects, but not remote sequential effects. Here, we present a new method for generating Latin squares that simultaneously counterbalance both immediate and remote sequential effects and assignment of stimuli to conditions. An Appendix is provided to facilitate implementation of these Latin square designs.

Task-dependent V1 responses in human retinitis pigmentosa.

PubMed

Masuda, Yoichiro; Horiguchi, Hiroshi; Dumoulin, Serge O; Furuta, Ayumu; Miyauchi, Satoru; Nakadomari, Satoshi; Wandell, Brian A

2010-10-01

During measurement with functional MRI (fMRI) during passive viewing, subjects with macular degeneration (MD) have a large unresponsive lesion projection zone (LPZ) in V1. fMRI responses can be evoked from the LPZ when subjects engage in a stimulus-related task. The authors report fMRI measurements on a different class of subjects, those with retinitis pigmentosa (RP), who have intact foveal vision but peripheral visual field loss. The authors measured three RP subjects and two control subjects. fMRI was performed while the subjects viewed drifting contrast pattern stimuli. The subjects passively viewed the stimuli or performed a stimulus-related task. During passive viewing, the BOLD response in the posterior calcarine cortex of all RP subjects was in phase with the stimulus. A bordering, anterior LPZ could be identified by responses that were in opposite phase to the stimulus. When the RP subjects made stimulus-related judgments, however, the LPZ responses changed: the responses modulated in phase with the stimulus and task. In control subjects, the responses in a simulated V1 LPZ were unchanged between the passive and the stimulus-related judgment conditions. Task-dependent LPZ responses are present in RP subjects, similar to responses measured in MD subjects. The results are consistent with the hypothesis that deleting the retinal input to the LPZ unmasks preexisting extrastriate feedback signals that are present across V1. The authors discuss the implications of this hypothesis for visual therapy designed to replace the missing V1 LPZ inputs and to restore vision.

Natural stimulation of the nonclassical receptive field increases information transmission efficiency in V1.

PubMed

Vinje, William E; Gallant, Jack L

2002-04-01

We have investigated how the nonclassical receptive field (nCRF) affects information transmission by V1 neurons during simulated natural vision in awake, behaving macaques. Stimuli were centered over the classical receptive field (CRF) and stimulus size was varied from one to four times the diameter of the CRF. Stimulus movies reproduced the spatial and temporal stimulus dynamics of natural vision while maintaining constant CRF stimulation across all sizes. In individual neurons, stimulation of the nCRF significantly increases the information rate, the information per spike, and the efficiency of information transmission. Furthermore, the population averages of these quantities also increase significantly with nCRF stimulation. These data demonstrate that the nCRF increases the sparseness of the stimulus representation in V1, suggesting that the nCRF tunes V1 neurons to match the highly informative components of the natural world.

Cofilin promotes stimulus-induced lamellipodium formation by generating an abundant supply of actin monomers

PubMed Central

Kiuchi, Tai; Ohashi, Kazumasa; Kurita, Souichi; Mizuno, Kensaku

2007-01-01

Cofilin stimulates actin filament disassembly and accelerates actin filament turnover. Cofilin is also involved in stimulus-induced actin filament assembly during lamellipodium formation. However, it is not clear whether this occurs by replenishing the actin monomer pool, through filament disassembly, or by creating free barbed ends, through its severing activity. Using photoactivatable Dronpa-actin, we show that cofilin is involved in producing more than half of all cytoplasmic actin monomers and that the rate of actin monomer incorporation into the tip of the lamellipodium is dependent on the size of this actin monomer pool. Finally, in cofilin-depleted cells, stimulus-induced actin monomer incorporation at the cell periphery is attenuated, but the incorporation of microinjected actin monomers is not. We propose that cofilin contributes to stimulus-induced actin filament assembly and lamellipodium extension by supplying an abundant pool of cytoplasmic actin monomers. PMID:17470633

Working memory contents revive the neglected, but suppress the inhibited.

PubMed

Han, Suk Won

2015-12-01

It is well known that attention is biased toward a stimulus matching working memory contents. However, it remains unknown whether the maintenance of information in working memory by itself is sufficient to create memory-driven attentional capture. Notably, in many previous studies showing the memory-driven attentional capture, the task settings might have explicitly or implicitly incentivized participants to strategically attend to a memory-matching stimulus. By innovating an experimental paradigm, the present study overcame this challenge and directly tested whether working memory contents capture attention in the absence of task-level attentional bias toward a memory-matching stimulus. I found that a stimulus that is usually outside the focus of attention, powerfully captured attention when it matched working memory contents, whereas a match between working memory and an inhibited stimulus suppressed attentional allocation toward the memory-matching stimulus. These findings suggest that in the absence of any task-level attentional bias toward memory-matching stimuli, attention is biased toward a memory-matching stimulus, but this memory-driven attentional capture is diminished when top-down inhibition is imposed on the stimulus. Copyright © 2015 Elsevier B.V. All rights reserved.

Small-volume amnioinfusion: a potential stimulus of intrapartum fetal heart rate accelerations.

PubMed

Wax, Joseph R; Flaherty, Nina; Pinette, Michael G; Blackstone, Jacquelyn; Cartin, Angelina

2004-02-01

We describe a recurrent nonreassuring fetal heart rate pattern in which small-volume amnioinfusions apparently evoked fetal heart rate accelerations suggested fetal well-being, allowing that progressive labor that culminated in the vaginal delivery of a healthy infant.

Naturalistic stimulation changes the dynamic response of action potential encoding in a mechanoreceptor

PubMed Central

Pfeiffer, Keram; French, Andrew S.

2015-01-01

Naturalistic signals were created from vibrations made by locusts walking on a Sansevieria plant. Both naturalistic and Gaussian noise signals were used to mechanically stimulate VS-3 slit-sense mechanoreceptor neurons of the spider, Cupiennius salei, with stimulus amplitudes adjusted to give similar firing rates for either stimulus. Intracellular microelectrodes recorded action potentials, receptor potential, and receptor current, using current clamp and voltage clamp. Frequency response analysis showed that naturalistic stimulation contained relatively more power at low frequencies, and caused increased neuronal sensitivity to higher frequencies. In contrast, varying the amplitude of Gaussian stimulation did not change neuronal dynamics. Naturalistic stimulation contained less entropy than Gaussian, but signal entropy was higher than stimulus in the resultant receptor current, indicating addition of uncorrelated noise during transduction. The presence of added noise was supported by measuring linear information capacity in the receptor current. Total entropy and information capacity in action potentials produced by either stimulus were much lower than in earlier stages, and limited to the maximum entropy of binary signals. We conclude that the dynamics of action potential encoding in VS-3 neurons are sensitive to the form of stimulation, but entropy and information capacity of action potentials are limited by firing rate. PMID:26578975

Conditioned pain modulation (CPM) in children and adolescents: Effects of sex and age

PubMed Central

Tsao, Jennie C. I.; Seidman, Laura C.; Evans, Subhadra; Lung, Kirsten C.; Zeltzer, Lonnie K.; Naliboff, Bruce D.

2013-01-01

Conditioned pain modulation (CPM) refers to the diminution of perceived pain intensity for a test stimulus following application of a conditioning stimulus to a remote area of the body, and is thought to reflect the descending inhibition of nociceptive signals. Studying CPM in children may inform interventions to enhance central pain inhibition within a developmental framework. We assessed CPM in 133 healthy children (mean age = 13 years; 52.6% girls) and tested the effects of sex and age. Participants were exposed to four trials of a pressure test stimulus before, during, and after the application of a cold water conditioning stimulus. CPM was documented by a reduction in pressure pain ratings during cold water administration. Older children (12–17 years) exhibited greater CPM than younger (8–11 years) children. No sex differences in CPM were found. Lower heart rate variability (HRV) at baseline and after pain induction was associated with less CPM controlling for child age. The findings of greater CPM in the older age cohort suggest a developmental improvement in central pain inhibitory mechanisms. The results highlight the need to examine developmental and contributory factors in central pain inhibitory mechanisms in children to guide effective, age appropriate, pain interventions. PMID:23541066

The noxious effects of electroimmobilization in adult Holstein cows: a pilot study.

PubMed Central

Pascoe, P J; McDonell, W N

1986-01-01

Ten adult Holstein cows were used in an experiment to determine whether the induction of electroimmobilization was a noxious event. The cows were halter trained and accustomed to being led into a set of stocks. The time taken for the cattle to walk the last ten metres into the stocks was recorded. The heart rate of the cow was recorded for a three minute period prior to a ten second exposure to a high pitched sound (the conditioning stimulus). Measurements were collected for three repetitions and then the cows were assigned to two groups of five. One group was immobilized for 30 seconds using a commercial electroimmobilizer, the other group was not treated. This procedure was repeated ten times over a period of eight days. The cows were then exposed to the conditioning stimulus and their response observed. The treated group took significantly (P less than 0.05) longer to get into the stocks and the regression slopes for heart rate were significantly different from the control group. The treated cows responded to the conditioning stimulus at five and nine months after the end of the conditioning period. Adult Holstein cows regarded electroimmobilization as a noxious event and were very strongly conditioned to this stimulus. PMID:3756681

Autoshaping in the rat: conditioned licking response to a stimulus that signals sucrose reinforcement.

PubMed

Reilly, Steve; Grutzmacher, Richard P.

2002-07-31

The present experiments were designed to determine if repeated presentations of an empty sipper tube (the conditioned stimulus or CS) with the response-independent delivery of a sucrose solution (the unconditioned stimulus or US) from a second spout results in the development of Pavlovian conditioned responding. In Experiment 1, rats in the experimental condition received paired CS-US presentations whereas subjects in the control condition were exposed to random presentations of CS and US. In Experiment 2, an additional control condition (CS alone) was included and, to encourage generalized responding between the US and CS, the CS tube was filled with water for all groups. The results of both experiments indicate that the CS-directed responding in the paired CS-US condition was Pavlovian in nature. Thus, the present procedure serves as an autoshaping task in which conditioned licking is generated.

Effects of inter-stimulus interval and intensity on the perceived urgency of tactile patterns.

PubMed

White, Timothy L; Krausman, Andrea S

2015-05-01

This research examines the feasibility of coding urgency into tactile patterns. Four tactile patterns were presented at either, 12 or 23.5 dB above mean threshold, with an ISI of either 0 (no interval) or 500 msec. Measures included pattern identification and urgency rating on a scale of 1 (least urgent) to 10 (most urgent). Two studies were conducted, a laboratory study and a field study. In the laboratory study, participants received the tactile patterns while seated in front of a computer. For the field study, participants performed dismounted Soldier maneuvers while receiving the tactile patterns. Higher identification rates were found for the 23.5 dB intensity. Patterns presented at the 23.5 dB intensity and no ISI were rated most urgent. No differences in urgency ratings were found for 12 dB based on ISI. Findings support the notion of coding urgency into tactile patterns as a way of augmenting tactile communication. Published by Elsevier Ltd.

Effects of aging, word frequency, and text stimulus quality on reading across the adult lifespan: Evidence from eye movements.

PubMed

Warrington, Kayleigh L; McGowan, Victoria A; Paterson, Kevin B; White, Sarah J

2018-04-19

Reductions in stimulus quality may disrupt the reading performance of older adults more when compared with young adults because of sensory declines that begin early in middle age. However, few studies have investigated adult age differences in the effects of stimulus quality on reading, and none have examined how this affects lexical processing and eye movement control. Accordingly, we report two experiments that examine the effects of reduced stimulus quality on the eye movements of young (18-24 years), middle-aged (41-51 years), and older (65+ years) adult readers. In Experiment 1, participants read sentences that contained a high- or low-frequency critical word and that were presented normally or with contrast reduced so that words appeared faint. Experiment 2 further investigated effects of reduced stimulus quality using a gaze-contingent technique to present upcoming text normally or with contrast reduced. Typical patterns of age-related reading difficulty (e.g., slower reading, more regressions) were observed in both experiments. In addition, eye movements were disrupted more for older than younger adults when all text (Experiment 1) or just upcoming text (Experiment 2) appeared faint. Moreover, there was an interaction between stimulus quality and word frequency (Experiment 1), such that readers fixated faint low-frequency words for disproportionately longer. Crucially, this effect was similar across all age groups. Thus, although older readers suffer more from reduced stimulus quality, this additional difficulty primarily affects their visual processing of text. These findings have important implications for understanding the role of stimulus quality on reading behavior across the lifespan. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Rapid Delivery of Cocaine Facilitates Acquisition of Self-Administration in Rats: An Effect Masked by Paired Stimuli

PubMed Central

Schindler, Charles W.; Cogan, Elizabeth S.; Thorndike, Eric B.; Panlilio, Leigh V.

2011-01-01

In general, faster infusions of cocaine are more likely to support behavior related to abuse than are slower infusions. However, some studies of cocaine self-administration in rats have failed to support this finding, possibly because the effect was masked by other factors. One such factor may be the pairing of a stimulus with the infusion, a procedure that is known to facilitate acquisition of drug self-administration. We compared fast and slow infusions by allowing groups of rats to acquire cocaine self-administration at a dose of 1 mg/kg/infusion, delivered over different durations (1.8 or 100 sec). Two groups were trained with either short or long infusions paired with a visual stimulus change (lights off), and two other groups were trained with short or long durations but with no stimulus change. Both groups trained with a paired stimulus acquired cocaine self-administration. With no stimulus change, the rats trained with the 1.8-sec infusion acquired cocaine self-administration at a rate comparable to the two groups that were trained with a paired stimulus. However, most rats in the group trained with the 100-sec infusion that was not accompanied by a stimulus change failed to acquire cocaine self-administration. The stimulus itself did not support responding. These results indicate that infusing a given dose of cocaine over a longer duration reduces its ability to support self-administration, but drug-paired stimuli can partially mask this effect by enhancing the effectiveness of slow infusions. PMID:21600912

Rapid delivery of cocaine facilitates acquisition of self-administration in rats: an effect masked by paired stimuli.

PubMed

Schindler, Charles W; Cogan, Elizabeth S; Thorndike, Eric B; Panlilio, Leigh V

2011-09-01

In general, faster infusions of cocaine are more likely to support behavior related to abuse than are slower infusions. However, some studies of cocaine self-administration in rats have failed to support this finding, possibly because the effect was masked by other factors. One such factor may be the pairing of a stimulus with the infusion, a procedure that is known to facilitate acquisition of drug self-administration. We compared fast and slow infusions by allowing groups of rats to acquire cocaine self-administration at a dose of 1mg/kg/infusion, delivered over different durations (1.8 or 100 s). Two groups were trained with either short or long infusions paired with a visual stimulus change (lights off), and two other groups were trained with short or long durations but with no stimulus change. Both groups trained with a paired stimulus acquired cocaine self-administration. With no stimulus change, the rats trained with the 1.8-s infusion acquired cocaine self-administration at a rate comparable to the two groups that were trained with a paired stimulus. However, most rats in the group trained with the 100-s infusion that was not accompanied by a stimulus change failed to acquire cocaine self-administration. The stimulus itself did not support responding. These results indicate that infusing a given dose of cocaine over a longer duration reduces its ability to support self-administration, but drug-paired stimuli can partially mask this effect by enhancing the effectiveness of slow infusions. Published by Elsevier Inc.

Preregistered Replication of "Affective Flexibility: Evaluative Processing Goals Shape Amygdala Activity".

PubMed

Lumian, Daniel S; McRae, Kateri

2017-09-01

The human amygdala is sensitive to stimulus characteristics, and growing evidence suggests that it is also responsive to cognitive framing in the form of evaluative goals. To examine whether different evaluations of stimulus characteristics shape amygdala activation, we conducted a preregistered replication of Cunningham, Van Bavel, and Johnsen's (2008) study demonstrating flexible mapping of amygdala activation to stimulus characteristics, depending on evaluative goals. Participants underwent functional MRI scanning while viewing famous names under three conditions: They were asked to report their overall attitude toward each name, their positive associations only, or their negative associations only. We observed an interaction between condition and rating type, identified as the effect of interest in Cunningham et al. (2008). Specifically, postscan positivity, but not negativity, ratings predicted left amygdala activation when participants were asked to evaluate positive, but not negative, associations with the names. These results provide convergent evidence that cognitive framing, in the form of evaluative goals, can significantly alter whether amygdala activation indexes positivity or negativity.

Motion onset does not capture attention when subsequent motion is "smooth".

PubMed

Sunny, Meera Mary; von Mühlenen, Adrian

2011-12-01

Previous research on the attentional effects of moving objects has shown that motion per se does not capture attention. However, in later studies it was argued that the onset of motion does capture attention. Here, we show that this motion-onset effect critically depends on motion jerkiness--that is, the rate at which the moving stimulus is refreshed. Experiment 1 used search displays with a static, a motion-onset, and an abrupt-onset stimulus, while systematically varying the refresh rate of the moving stimulus. The results showed that motion onset only captures attention when subsequent motion is jerky (8 and 17 Hz), not when it is smooth (33 and 100 Hz). Experiment 2 replaced motion onset with continuous motion, showing that motion jerkiness does not affect how continuous motion is processed. These findings do not support accounts that assume a special role for motion onset, but they are in line with the more general unique-event account.

Perceived duration decreases with increasing eccentricity.

PubMed

Kliegl, Katrin M; Huckauf, Anke

2014-07-01

Previous studies examining the influence of stimulus location on temporal perception yield inhomogeneous and contradicting results. Therefore, the aim of the present study is to soundly examine the effect of stimulus eccentricity. In a series of five experiments, subjects compared the duration of foveal disks to disks presented at different retinal eccentricities on the horizontal meridian. The results show that the perceived duration of a visual stimulus declines with increasing eccentricity. The effect was replicated with various stimulus orders (Experiments 1-3), as well as with cortically magnified stimuli (Experiments 4-5), ruling out that the effect was merely caused by different cortical representation sizes. The apparent decreasing duration of stimuli with increasing eccentricity is discussed with respect to current models of time perception, the possible influence of visual attention and respective underlying physiological characteristics of the visual system. Copyright © 2014 Elsevier B.V. All rights reserved.

Masking of Figure-Ground Texture and Single Targets by Surround Inhibition: A Computational Spiking Model

PubMed Central

Supèr, Hans; Romeo, August

2012-01-01

A visual stimulus can be made invisible, i.e. masked, by the presentation of a second stimulus. In the sensory cortex, neural responses to a masked stimulus are suppressed, yet how this suppression comes about is still debated. Inhibitory models explain masking by asserting that the mask exerts an inhibitory influence on the responses of a neuron evoked by the target. However, other models argue that the masking interferes with recurrent or reentrant processing. Using computer modeling, we show that surround inhibition evoked by ON and OFF responses to the mask suppresses the responses to a briefly presented stimulus in forward and backward masking paradigms. Our model results resemble several previously described psychophysical and neurophysiological findings in perceptual masking experiments and are in line with earlier theoretical descriptions of masking. We suggest that precise spatiotemporal influence of surround inhibition is relevant for visual detection. PMID:22393370

Configural Representations in Spatial Working Memory: Modulation by Perceptual Segregation and Voluntary Attention

PubMed Central

Gmeindl, Leon; Nelson, James K.; Wiggin, Timothy; Reuter-Lorenz, Patricia A.

2011-01-01

In what form are multiple spatial locations represented in working memory? The current study revealed that people often maintain the configural properties (inter-item relationships) of visuospatial stimuli even when this information is explicitly task-irrelevant. However, results also indicate that the voluntary allocation of selective attention prior to stimulus presentation, as well as feature-based perceptual segregation of relevant from irrelevant stimuli, can eliminate the influences of stimulus configuration on location change detection performance. In contrast, voluntary attention cued to the relevant target location following presentation of the stimulus array failed to attenuate these influences. Thus, whereas voluntary selective attention can isolate or prevent the encoding of irrelevant stimulus locations and configural properties, people, perhaps due to limitations in attentional resources, reliably fail to isolate or suppress configural representations that have been encoded into working memory. PMID:21761373

Edges, colour and awareness in blindsight.

PubMed

Alexander, Iona; Cowey, Alan

2010-06-01

It remains unclear what is being processed in blindsight in response to faces, colours, shapes, and patterns. This was investigated in two hemianopes with chromatic and achromatic stimuli with sharp or shallow luminance or chromatic contrast boundaries or temporal onsets. Performance was excellent only when stimuli had sharp spatial boundaries. When discrimination between isoluminant coloured Gaussians was good it declined to chance levels if stimulus onset was slow. The ability to discriminate between instantaneously presented colours in the hemianopic field depended on their luminance, indicating that wavelength discrimination totally independent of other stimulus qualities is absent. When presented with narrow-band colours the hemianopes detected a stimulus maximally effective for S-cones but invisible to M- and L-cones, indicating that blindsight is mediated not just by the mid-brain, which receives no S-cone input, or that the rods contribute to blindsight. The results show that only simple stimulus features are processed in blindsight. 2010 Elsevier Inc. All rights reserved.

Negative arousal increases the effects of stimulus salience in older adults.

PubMed

Sutherland, Matthew R; Mather, Mara

2015-01-01

BACKGROUND/STUDY CONTEXT: Stimuli compete for mental representation, with salient stimuli attracting more attention than less salient stimuli. In a recent study, we found that presenting an emotionally negative arousing sound before briefly showing an array of letters with different levels of salience increased the reporting of the more salient letters but decreased reporting of the less salient letters (Sutherland & Mather, 2012, Emotion, 12, 1367-1372). In the current study we examined whether negative arousal produces similar effects on attention in older adults. Data from 55 older adults (61-80 years; M = 70.7, SD = 5.1) were compared with those from 110 younger adults (18-29 years; M = 20.3, SD = 2.3) from Sutherland and Mather (2012). Neutral or negative arousing sound clips were played before a brief presentation of eight letters, three of which were presented in a darker font than the others to create a group of high- and low-salience targets. Next, participants recalled as many of the letters as they could. At the end of the study, participants rated the emotional arousal and the valence of the sounds. Higher ratings of emotional arousal for the sounds predicted a greater advantage for high-salience letters in recall. This influence of arousal did not significantly differ by age. The effects of negative arousal on subsequent attention were similar in older adults as in younger adults. Moreover, the results support arousal-biased competition theory (Mather & Sutherland, 2011, Perspectives on Psychological Science, 6, 114-133), which predicts that emotional arousal amplifies the effects of stimulus salience in attention and memory.

Entracking as a Brain Stem Code for Pitch: The Butte Hypothesis.

PubMed

Joris, Philip X

2016-01-01

The basic nature of pitch is much debated. A robust code for pitch exists in the auditory nerve in the form of an across-fiber pooled interspike interval (ISI) distribution, which resembles the stimulus autocorrelation. An unsolved question is how this representation can be "read out" by the brain. A new view is proposed in which a known brain-stem property plays a key role in the coding of periodicity, which I refer to as "entracking", a contraction of "entrained phase-locking". It is proposed that a scalar rather than vector code of periodicity exists by virtue of coincidence detectors that code the dominant ISI directly into spike rate through entracking. Perfect entracking means that a neuron fires one spike per stimulus-waveform repetition period, so that firing rate equals the repetition frequency. Key properties are invariance with SPL and generalization across stimuli. The main limitation in this code is the upper limit of firing (~ 500 Hz). It is proposed that entracking provides a periodicity tag which is superimposed on a tonotopic analysis: at low SPLs and fundamental frequencies > 500 Hz, a spectral or place mechanism codes for pitch. With increasing SPL the place code degrades but entracking improves and first occurs in neurons with low thresholds for the spectral components present. The prediction is that populations of entracking neurons, extended across characteristic frequency, form plateaus ("buttes") of firing rate tied to periodicity.

The dynamic-stimulus advantage of visual symmetry perception.

PubMed

Niimi, Ryosuke; Watanabe, Katsumi; Yokosawa, Kazuhiko

2008-09-01

It has been speculated that visual symmetry perception from dynamic stimuli involves mechanisms different from those for static stimuli. However, previous studies found no evidence that dynamic stimuli lead to active temporal processing and improve symmetry detection. In this study, four psychophysical experiments investigated temporal processing in symmetry perception using both dynamic and static stimulus presentations of dot patterns. In Experiment 1, rapid successive presentations of symmetric patterns (e.g., 16 patterns per 853 ms) produced more accurate discrimination of orientations of symmetry axes than static stimuli (single pattern presented through 853 ms). In Experiments 2-4, we confirmed that the dynamic-stimulus advantage depended upon presentation of a large number of unique patterns within a brief period (853 ms) in the dynamic conditions. Evidently, human vision takes advantage of temporal processing for symmetry perception from dynamic stimuli.

A loud auditory stimulus overcomes voluntary movement limitation in cervical dystonia.

PubMed

Serranová, Tereza; Jech, Robert; Martí, Maria José; Modreanu, Raluca; Valldeoriola, Francesc; Sieger, Tomáš; Růžička, Evžen; Valls-Solé, Josep

2012-01-01

Patients with cervical dystonia (CD) present with an impaired performance of voluntary neck movements, which are usually slow and limited. We hypothesized that such abnormality could involve defective preparation for task execution. Therefore, we examined motor preparation in CD patients using the StartReact method. In this test, a startling auditory stimulus (SAS) is delivered unexpectedly at the time of the imperative signal (IS) in a reaction time task to cause a faster execution of the prepared motor programme. We expected that CD patients would show an abnormal StartReact phenomenon. Fifteen CD patients and 15 age matched control subjects (CS) were asked to perform a rotational movement (RM) to either side as quick as possible immediately after IS perception (a low intensity electrical stimulus to the II finger). In randomly interspersed test trials (25%) a 130 dB SAS was delivered simultaneously with the IS. We recorded RMs in the horizontal plane with a high speed video camera (2.38 ms per frame) in synchronization with the IS. The RM kinematic-parameters (latency, velocity, duration and amplitude) were analyzed using video-editing software and screen protractor. Patients were asked to rate the difficulty of their RMs in a numerical rating scale. In control trials, CD patients executed slower RMs (repeated measures ANOVA, p<0.10(-5)), and reached a smaller final head position angle relative to the midline (p<0.05), than CS. In test trials, SAS improved all RMs in both groups (p<0.10(-14)). In addition, patients were more likely to reach beyond their baseline RM than CS (χ(2), p<0.001) and rated their performance better than in control trials (t-test, p<0.01). We found improvement of kinematic parameters and subjective perception of motor performance in CD patients with StartReact testing. Our results suggest that CD patients reach an adequate level of motor preparation before task execution.

A measurement theory of illusory conjunctions.

PubMed

Prinzmetal, William; Ivry, Richard B; Beck, Diane; Shimizu, Naomi

2002-04-01

Illusory conjunctions refer to the incorrect perceptual combination of correctly perceived features, such as color and shape. Research on the phenomenon has been hampered by the lack of a measurement theory that accounts for guessing features, as well as the incorrect combination of correctly perceived features. Recently, several investigators have suggested using multinomial models as a tool for measuring feature integration. The authors examined the adequacy of these models in 2 experiments by testing whether model parameters reflect changes in stimulus factors. In a third experiment, confidence ratings were used as a tool for testing the model. Multinomial models accurately reflected both variations in stimulus factors and observers' trial-by-trial confidence ratings.

Selective population rate coding: a possible computational role of gamma oscillations in selective attention.

PubMed

Masuda, Naoki

2009-12-01

Selective attention is often accompanied by gamma oscillations in local field potentials and spike field coherence in brain areas related to visual, motor, and cognitive information processing. Gamma oscillations are implicated to play an important role in, for example, visual tasks including object search, shape perception, and speed detection. However, the mechanism by which gamma oscillations enhance cognitive and behavioral performance of attentive subjects is still elusive. Using feedforward fan-in networks composed of spiking neurons, we examine a possible role for gamma oscillations in selective attention and population rate coding of external stimuli. We implement the concept proposed by Fries ( 2005 ) that under dynamic stimuli, neural populations effectively communicate with each other only when there is a good phase relationship among associated gamma oscillations. We show that the downstream neural population selects a specific dynamic stimulus received by an upstream population and represents it by population rate coding. The encoded stimulus is the one for which gamma rhythm in the corresponding upstream population is resonant with the downstream gamma rhythm. The proposed role for gamma oscillations in stimulus selection is to enable top-down control, a neural version of time division multiple access used in communication engineering.

Heart rate reactivity associated to positive and negative food and non-food visual stimuli.

PubMed

Kuoppa, Pekka; Tarvainen, Mika P; Karhunen, Leila; Narvainen, Johanna

2016-08-01

Using food as a stimuli is known to cause multiple psychophysiological reactions. Heart rate variability (HRV) is common tool for assessing physiological reactions in autonomic nervous system. However, the findings in HRV related to food stimuli have not been consistent. In this paper the quick changes in HRV related to positive and negative food and non-food visual stimuli are investigated. Electrocardiogram (ECG) was measured from 18 healthy females while being stimulated with the pictures. Subjects also filled Three-Factor Eating Questionnaire to determine their eating behavior. The inter-beat-interval time series and the HRV parameters were extracted from the ECG. The quick change in HRV parameters were studied by calculating the change from baseline value (10 s window before stimulus) to value after the onset of the stimulus (10 s window during stimulus). The paired t-test showed significant difference between positive and negative food pictures but not between positive and negative non-food pictures. All the HRV parameters decreased for positive food pictures while they stayed the same or increased a little for negative food pictures. The eating behavior characteristic cognitive restraint was negatively correlated with HRV parameters that describe decreasing of heart rate.

Using Roadside Billboard Posters to Increase Admission Rates to Problem Gambling Services: Reflections on Failure.

PubMed

Calderwood, Kimberly A; Wellington, William J

2015-07-01

Based on the stimulus-response model of advertising, this study sought to increase admission rates to a local problem gambling service (PGS) in Windsor, Ontario, Canada, by adding a series of locally based 10 foot by 20 foot roadside billboard posters to PGS's existing communications tools for a 24-week period. Using proof of performance reports, a pre-post survey of new callers to PGS, a website visit counter, and a media awareness survey, the findings showed that at least some individuals were influenced by billboard exposure, but admission rates continued to decline during the billboard campaign period. While one possible explanation for the communications failure was that the whole PGS communications campaign was below the minimal threshold for communications perception, another possible explanation is that the stimulus-response model of advertising used may not have been appropriate for such advertising that targets behavior change. Reflections on using an information-processing model instead of a stimulus-response model, and considerations of a two-step flow of communication, are provided. Recommendations are made regarding matching communications messages to stages of behavior change, use of online promotion, and strategies for future research. © 2015 Society for Public Health Education.

Olfactory perception of chemically diverse molecules.

PubMed

Keller, Andreas; Vosshall, Leslie B

2016-08-08

Understanding the relationship between a stimulus and how it is perceived reveals fundamental principles about the mechanisms of sensory perception. While this stimulus-percept problem is mostly understood for color vision and tone perception, it is not currently possible to predict how a given molecule smells. While there has been some progress in predicting the pleasantness and intensity of an odorant, perceptual data for a larger number of diverse molecules are needed to improve current predictions. Towards this goal, we tested the olfactory perception of 480 structurally and perceptually diverse molecules at two concentrations using a panel of 55 healthy human subjects. For each stimulus, we collected data on perceived intensity, pleasantness, and familiarity. In addition, subjects were asked to apply 20 semantic odor quality descriptors to these stimuli, and were offered the option to describe the smell in their own words. Using this dataset, we replicated several previous correlations between molecular features of the stimulus and olfactory perception. The number of sulfur atoms in a molecule was correlated with the odor quality descriptors "garlic," "fish," and "decayed," and large and structurally complex molecules were perceived to be more pleasant. We discovered a number of correlations in intensity perception between molecules. We show that familiarity had a strong effect on the ability of subjects to describe a smell. Many subjects used commercial products to describe familiar odorants, highlighting the role of prior experience in verbal reports of olfactory perception. Nonspecific descriptors like "chemical" were applied frequently to unfamiliar odorants, and unfamiliar odorants were generally rated as neither pleasant nor unpleasant. We present a very large psychophysical dataset and use this to correlate molecular features of a stimulus to olfactory percept. Our work reveals robust correlations between molecular features and perceptual qualities, and highlights the dominant role of familiarity and experience in assigning verbal descriptors to odorants.

Object form discontinuity facilitates displacement discrimination across saccades.

PubMed

Demeyer, Maarten; De Graef, Peter; Wagemans, Johan; Verfaillie, Karl

2010-06-01

Stimulus displacements coinciding with a saccadic eye movement are poorly detected by human observers. In recent years, converging evidence has shown that this phenomenon does not result from poor transsaccadic retention of presaccadic stimulus position information, but from the visual system's efforts to spatially align presaccadic and postsaccadic perception on the basis of visual landmarks. It is known that this process can be disrupted, and transsaccadic displacement detection performance can be improved, by briefly blanking the stimulus display during and immediately after the saccade. In the present study, we investigated whether this improvement could also follow from a discontinuity in the task-irrelevant form of the displaced stimulus. We observed this to be the case: Subjects more accurately identified the direction of intrasaccadic displacements when the displaced stimulus simultaneously changed form, compared to conditions without a form change. However, larger improvements were still observed under blanking conditions. In a second experiment, we show that facilitation induced by form changes and blanks can combine. We conclude that a strong assumption of visual stability underlies the suppression of transsaccadic change detection performance, the rejection of which generalizes from stimulus form to stimulus position.

Emergent Stimulus Relations Depend on Stimulus Correlation and Not on Reinforcement Contingencies

PubMed Central

Minster, Sara Tepaeru; Elliffe, Douglas; Muthukumaraswamy, Suresh D

2011-01-01

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 or Cx stimuli as samples, choices of Bx were reinforced and choices of Gx or Hx were not. Tests for symmetry, and combined symmetry and transitivity, showed the emergence of three 3-member (AxBxCx) stimulus classes in 5 of 5 human participants. Subsequent tests for all possible emergent relations between Ax, Bx, Cx and the class-specific incorrect comparisons Gx and Hx showed that these relations emerged for 4 of 5 the participants after extended overtraining of the baseline relations. These emergent relations must have been based on stimulus–stimulus correlations, and were not properties of the trained discriminated operants, because they required control by relations explicitly extinguished during training. This result supports theoretical accounts of emergent relations that emphasize stimulus correlation over operant contingencies. PMID:21547070

Learning to fear a second-order stimulus following vicarious learning.

PubMed

Reynolds, Gemma; Field, Andy P; Askew, Chris

2017-04-01

Vicarious fear learning refers to the acquisition of fear via observation of the fearful responses of others. The present study aims to extend current knowledge by exploring whether second-order vicarious fear learning can be demonstrated in children. That is, whether vicariously learnt fear responses for one stimulus can be elicited in a second stimulus associated with that initial stimulus. Results demonstrated that children's (5-11 years) fear responses for marsupials and caterpillars increased when they were seen with fearful faces compared to no faces. Additionally, the results indicated a second-order effect in which fear-related learning occurred for other animals seen together with the fear-paired animal, even though the animals were never observed with fearful faces themselves. Overall, the findings indicate that for children in this age group vicariously learnt fear-related responses for one stimulus can subsequently be observed for a second stimulus without it being experienced in a fear-related vicarious learning event. These findings may help to explain why some individuals do not recall involvement of a traumatic learning episode in the development of their fear of a specific stimulus.

Check in the Mail or More in the Paycheck: Does the Effectiveness of Fiscal Stimulus Depend on How It Is Delivered?†

PubMed Central

Sahm, Claudia R.; Shapiro, Matthew D.; Slemrod, Joel

2013-01-01

Recent fiscal policies, including the 2008 stimulus payments and the 2009 Making Work Pay Tax Credit, aimed to increase household spending. This paper quantifies the spending response to these policies and examines differences in spending by whether the stimulus was delivered as a one-time payment or as a flow of payments from reduced withholding. Based on responses from a representative sample of households in the Thomson Reuters University of Michigan Surveys of Consumers, the paper finds that the reduction in withholding in 2009 boosted spending at roughly half the rate (13 percent) as the one-time payments (25 percent) in 2008. PMID:23970951

Self-face Captures, Holds, and Biases Attention.

PubMed

Wójcik, Michał J; Nowicka, Maria M; Kotlewska, Ilona; Nowicka, Anna

2017-01-01

The implicit self-recognition process may take place already in the pre-attentive stages of perception. After a silent stimulus has captured attention, it is passed on to the attentive stage where it can affect decision making and responding. Numerous studies show that the presence of self-referential information affects almost every cognitive level. These effects may share a common and fundamental basis in an attentional mechanism, conceptualized as attentional bias: the exaggerated deployment of attentional resources to a salient stimulus. A gold standard in attentional bias research is the dot-probe paradigm. In this task, a prominent stimulus (cue) and a neutral stimulus are presented in different spatial locations, followed by the presentation of a target. In the current study we aimed at investigating whether the self-face captures, holds and biases attention when presented as a task-irrelevant stimulus. In two dot-probe experiments coupled with the event-related potential (ERP) technique we analyzed the following relevant ERPs components: N2pc and SPCN which reflect attentional shifts and the maintenance of attention, respectively. An inter-stimulus interval separating face-cues and probes (800 ms) was introduced only in the first experiment. In line with our predictions, in Experiment 1 the self-face elicited the N2pc and the SPCN component. In Experiment 2 in addition to N2pc, an attentional bias was observed. Our results indicate that unintentional self-face processing disables the top-down control setting to filter out distractors, thus leading to the engagement of attentional resources and visual short-term memory.

RULES OF COMPETITIVE STIMULUS SELECTION IN A CHOLINERGIC ISTHMIC NUCLEUS OF THE OWL MIDBRAIN

PubMed Central

Asadollahi, Ali; Mysore, Shreesh P.; Knudsen, Eric I.

2011-01-01

In a natural scene, multiple stimuli compete for the control of gaze direction and attention. The nucleus isthmi pars parvocellularis (Ipc) is a cholinergic, midbrain nucleus that is reciprocally interconnected to the optic tectum, a structure known to be involved in the control of gaze and attention. Previous research has shown that the responses of many Ipc units to a visual stimulus presented inside the classical receptive field (RF) can be powerfully inhibited when the strength of a distant, competing stimulus becomes the stronger stimulus. This study investigated further the nature of competitive interactions in the Ipc of owls by employing two complementary protocols: in the first protocol, we measured the effects of a distant stimulus on responses to an RF stimulus located at different positions inside the RF; in the second protocol, we measured the effects of a distant stimulus on responses to RF stimuli of different strengths. The first protocol demonstrated that the effect of a competing stimulus is purely divisive: the competitor caused a proportional reduction in responses to the RF stimulus that did not alter either the location or sharpness of spatial tuning. The second protocol demonstrated that, for most units, the strength of this divisive inhibition is regulated powerfully by the relative strengths of the competing stimuli: inhibition was strong when the competitor was the stronger stimulus and weak when the competitor was the weaker stimulus. The data indicate that competitive interactions in the Ipc depend on feedback and a globally divisive inhibitory network. PMID:21508234