Sequence Of Stimuli Research Articles

A-46 MMA Athletes Demonstrate Different Brain Vital Sign Profiles Compared to Matched Controls at “Baseline”

Abstract Purpose We compared objective brain vital sign metrics derived from event-related potentials (ERPs) of mixed martial arts (MMA) athletes and matched control participants. Methods We recorded 101 successful EEG scans from 12 MMA athletes (24.8 ± 2.6 yr) and 18 matched control participants (26.5±3.5 yr). For this analysis, only “baseline” scans were considered (n=30). “Baseline” was at least 90 days from a previous fight and 90 days (MMA) or 1 year (control) following medical clearance from a previously diagnosed concussion. We derived objective, clinical metrics (brain vital signs) from ERPs for auditory sensation (N100), basic attention (P300), and cognitive processing (N400) evoked while participants listen to a 6-minute auditory stimulus sequence. EEG data were processed using standard methods. N100, P300, and N400 amplitudes and latencies were manually identified on evoked potential waveforms by a blinded reviewer. Differences between groups at the waveform level were evaluated with a mass-univariate analysis using non-parametric resampling. Brain vital signs were compared across groups with a Kruskal-Wallis H-test for independent samples, with FDR correction for multiple comparisons. Results Mass-univariate waveform analyses showed significant differences (P < 0.05) between MMA athletes and controls in both P300 and N400 ERPs. The Kruskal-Wallis test identified a significant difference in N400 amplitude (H=7.04, P=.008, Padj=.047) between MMA athletes and controls. Conclusions MMA athletes demonstrate significant differences in “baseline” brain vital signs compared to controls, indicating that exposure to repetitive head impacts in MMA may be associated with subconcussive changes in brain function.

Probabilistic integration of preceding responses explains response bias in perceptual decision making

Expectations of sensory information change not only how well but also what we perceive. Even in an unpredictable environment, the brain is by default constantly engaged in computing probabilities between sensory events. These estimates are used to generate predictions about future sensory events. Here, we investigated the predictability of behavioral responses using three different learning models in three different one-interval two-alternative forced choice experiments with either auditory, vestibular, or visual stimuli. Results indicate that recent decisions, instead of the sequence of generative stimuli, cause serial dependence. By bridging the gap between sequence learning and perceptual decision making, we provide a novel perspective on sequential choice effects. We propose that serial biases reflect the tracking of statistical regularities of the decision variable, offering a broader understanding of this phenomenon.

Effects of Stimulus Frequency and Location on Vibrotactile Discrimination Performance Using Voice Coil Actuators on the Forearm

What are the effects of frequency variation of vibrotactile stimuli on localization acuity? The precise localization of vibrotactile stimuli is crucial for applications that are aimed at conveying vibrotactile information. In order to evaluate the ability to distinguish between vibrotactile stimuli based on their frequency and location on the forearm, we used a relative point localization method. Participants were presented with pairs of sequential vibrotactile stimuli at three possible locations on the forearm and asked to determine whether the second stimulation occurred at the same location as the first one in the pair or not. The stimulation frequency varied between 100 Hz, 150 Hz, 200 Hz and 250 Hz, which covers the range of frequencies that human observers are most sensitive to. The amplitude was kept constant. Our results revealed that the ability to discriminate between actuators remained unaffected by variations in the frequency of vibrotactile stimulation within the tested frequency range. The accuracy of the tactile discrimination task was heavily dependent on the location of the stimulation on the forearm, with the highest accuracy close to the wrist and elbow, locations that may serve as tactile anchor points. Our results highlight the critical role of stimulation location in precise vibrotactile localization and the importance of careful consideration of location in the design of forearm-mounted vibrotactile devices.

Reliability and stability of oddball P300 amplitude in older adults: The role of stimulus sequence effects

The P300 may be an individual difference marker of neuro-cognitive function, which due to age-related cognitive decline may be particularly useful in older adults. Recently, we reported effects of the local stimulus sequence in an oddball task (i.e., the number of non-targets that preceded a target) on P300 amplitude in young and older adults. The same older adults completed a second session of the task 4–8 months after the first session. Here, we examined the effect of the stimulus sequence on the between- and within-session reliability and stability of P300 amplitude and RT, and their intertrial variability, in this sample of older adults. The sequence effects – an inverted U-shape effect of the number of standards preceding a target on parietal P300, and a linear effect on frontal P300 - were stable within and across sessions on the group level. Within individuals, P300 amplitude at frontal and parietal electrodes was generally very reliable and stable, mostly independently of sequence effects, encouraging its use as an individual difference marker of neuro-cognitive function in older adults. However, measures of the strength of the sequence effects themselves showed unacceptable reliability, speaking against their use as individual difference markers, at least in older adults.

Variance aftereffect within and between sensory modalities for visual and auditory domains.

We can grasp various features of the outside world using summary statistics efficiently. Among these statistics, variance is an index of information homogeneity or reliability. Previous research has shown that visual variance information in the context of spatial integration is encoded directly as a unique feature, and currently perceived variance can be distorted by that of the preceding stimuli. In this study, we focused on variance perception in temporal integration. We investigated whether any variance aftereffects occurred in visual size and auditory pitch. Furthermore, to examine the mechanism of cross-modal variance perception, we also investigated whether variance aftereffects occur between different modalities. Four experimental conditions (a combination of sensory modalities of adaptor and test: visual-to-visual, visual-to-auditory, auditory-to-auditory, and auditory-to-visual) were conducted. Participants observed a sequence of visual or auditory stimuli perturbed in size or pitch with certain variance and performed a variance classification task before and after the variance adaptation phase. We found that in visual size, within modality adaptation to small or large variance, resulted in a variance aftereffect, indicating that variance judgments are biased in the direction away from that of the adapting stimulus. In auditory pitch, within modality adaptation to small variance caused variance aftereffect. For cross-modal combinations, adaptation to small variance in visual size resulted in variance aftereffect. However, the effect was weak, and variance aftereffect did not occur in other conditions. These findings indicate that the variance information of sequentially presented stimuli is encoded independently in visual and auditory domains.

Maternal pandemic-related stress during pregnancy associates with infants' socio-cognitive development at 12 months: A longitudinal multi-centric study.

Prenatal maternal stress is a key risk factor for infants' development. Previous research has highlighted consequences for infants' socio-emotional and cognitive outcomes, but less is known for what regards socio-cognitive development. In this study, we report on the effects of maternal prenatal stress related to the COVID-19 pandemic on 12-month-old infants' behavioral markers of socio-cognitive development. Ninety infants and their mothers provided complete longitudinal data from birth to 12 months. At birth, mothers reported on pandemic-related stress during pregnancy. At infants' 12-month-age, a remote mother-infant interaction was videotaped: after an initial 2-min face-to-face episode, the experimenter remotely played a series of four auditory stimuli (2 human and 2 non-human sounds). The auditory stimuli sequence was counterbalanced among participants and each sound was repeated three times every 10 seconds (Exposure, 30 seconds) while mothers were instructed not to interact with their infants and to display a neutral still-face expression. Infants' orienting, communication, and pointing toward the auditory source was coded micro-analytically and a socio-cognitive score (SCS) was obtained by means of a principal component analysis. Infants equally oriented to human and non-human auditory stimuli. All infants oriented toward the sound during the Exposure episode, 80% exhibited any communication directed to the auditory source, and 48% showed at least one pointing toward the sound. Mothers who reported greater prenatal pandemic-related stress had infants with higher probability of showing no communication, t = 2.14 (p = .035), or pointing, t = 1.93 (p = .057). A significant and negative linear association was found between maternal prenatal pandemic-related stress and infants' SCS at 12 months, R2 = .07 (p = .010), while adjusting for potential confounders. This study suggests that prenatal maternal stress during the COVID-19 pandemic might have increased the risk of an altered socio-cognitive development in infants as assessed through an observational paradigm at 12 months. Special preventive attention should be devoted to infants born during the pandemic.

Ventricular tachyarrhythmia treatment and prevention by subthreshold stimulation with stretchable epicardial multichannel electrode array

The implantable cardioverter-defibrillator (ICD) is an effective method to prevent sudden cardiac death in high-risk patients. However, the transvenous lead is incompatible with large-area electrophysiological mapping and cannot accommodate selective multichannel precision stimulations. Moreover, it involves high-energy shocks, resulting in pain, myocardial damage, and recurrences of ventricular tachyarrhythmia (VTA). We present a method for VTA treatment based on subthreshold electrical stimulations using a stretchable epicardial multichannel electrode array, which does not disturb the normal contraction or electrical propagation of the ventricle. In rabbit models with myocardial infarction, the infarction was detected by mapping intracardiac electrograms with the stretchable epicardial multichannel electrode array. Then, VTAs could be terminated by sequential electrical stimuli from the epicardial multichannel electrode array beginning with low-energy subthreshold stimulations. Last, we used these subthreshold stimulations to prevent the occurrence of additional VTAs. The proposed protocol using the stretchable epicardial multichannel electrode array provides opportunities toward the development of innovative methods for painless ICD therapy.

Fixation-related visual mismatch negativity.

Vision under natural conditions could be studied by combining electroencephalogram (EEG) and eye tracking as well as using saccades as triggers for the onset of the fixation-related potentials (FRPs) and for the oculomotor inhibition (OMI) that follows every saccade. The result of this analysis is thought to be equivalent to the event-related response following a peripheral preview. Previous studies that measured responses to visual deviants in a sequence of flashed stimuli found an increased negativity in the occipital N1 component (visual mismatch negativity [vMMN]), and prolonged saccadic inhibition for unexpected events. The aim of the current study was to develop an oddball paradigm in constrained natural-viewing and determine whether a similar mismatched FRP and prolonged OMI for deviance could be found. To this end, we developed a visual oddball paradigm on a static display to generate expectancy and surprise across successive saccades. Observers (n = 26) inspected, one after the other, seven small patterns of E and an inverted E arranged on the screen along a horizontal path, with one frequent (standard) and one rare (deviant), looking for a superimposed tiny dot target in each 5-second trial. Our results show a significantly larger FRP-N1 negativity for the deviant, compared with the standard and prolonged OMI of the following saccade, as previously found for transient oddballs. Our results show, for the first time, prolonged OMI and stronger fixation-related N1 to a task-irrelevant visual mismatch (vMMN) in natural, but task-guided viewing. These two signals combined could serve as markers of prediction error in free viewing.

Differential Effects of Transcranial Static Magnetic Stimulation Over Left and Right Dorsolateral Prefrontal Cortex on Brain Oscillatory Responses During a Working Memory Task

Transcranial static magnetic stimulation (tSMS) is known to influence behavioral and neural activities. However, although the left and right dorsolateral prefrontal cortex (DLPFC) are associated with different cognitive functions, there remains a lack of knowledge on a difference in the effects of tSMS on cognitive performance and related brain activity between left and right DLPFC stimulations. To address this knowledge gap, we examined how differently tSMS over the left and right DLPFC altered working memory performance and electroencephalographic oscillatory responses using a 2-back task, in which subjects monitor a sequence of stimuli and decide whether a presented stimulus matches the stimulus presented two trials previously. Fourteen healthy adults (five females) performed the 2-back task before, during (20 min after the start of stimulation), immediately after, and 15 min after three different stimulation conditions: tSMS over the left DLPFC, tSMS over the right DLPFC, and sham stimulation. Our preliminary results revealed that while tSMS over the left and right DLPFC impaired working memory performance to a similar extent, the impacts of tSMS on brain oscillatory responses were different between the left and right DLPFC stimulations. Specifically, tSMS over the left DLPFC increased the event-related synchronization in beta band whereas tSMS over the right DLPFC did not show such an effect. These findings support evidence that the left and right DLPFC play different roles in working memory and suggest that the neural mechanism underlying the impairment of working memory by tSMS can be different between left and right DLPFC stimulations.

Pre-stimulus beta power varies as a function of auditory-motor synchronization and temporal predictability.

Auditory-motor interactions can support the preparation for expected sensory input. We investigated the periodic modulation of beta activity in the electroencephalogram to assess the role of active auditory-motor synchronization. Pre-stimulus beta activity (13-30 Hz) has been interpreted as a neural signature of the preparation for expected sensory input. In the current study, participants silently counted frequency deviants in sequences of pure tones either during a physically inactive control condition or while pedaling on a cycling ergometer. Tones were presented either rhythmically (at 1 Hz) or arrhythmically with variable intervals. In addition to the pedaling conditions with rhythmic (auditory-motor synchronization, AMS) or arrhythmic stimulation, a self-generated stimulus condition was used in which tones were presented in sync with the participants' spontaneous pedaling. This condition served to explore whether sensory predictions are driven primarily by the auditory or by the motor system. Pre-stimulus beta power increased for rhythmic compared to arrhythmic stimulus presentation in both sitting and pedaling conditions but was strongest in the AMS condition. Furthermore, beta power in the AMS condition correlated with motor performance, i.e., the better participants synchronized with the rhythmic stimulus sequence, the higher was pre-stimulus beta power. Additionally, beta power was increased for the self-generated stimulus condition compared with arrhythmic pedaling, but there was no difference between the self-generated and the AMS condition. The current data pattern indicates that pre-stimulus beta power is not limited to neuronal entrainment (i.e., periodic stimulus presentation) but represents a more general correlate of temporal anticipation. Its association with the precision of AMS supports the role of active behavior for auditory predictions.

The role of attention control in visual mismatch negativity (vMMN) studies

The detection of unattended visual changes is investigated by the visual mismatch negativity (vMMN) component of event-related potentials (ERPs). The vMMN is measured as the difference between the ERPs to infrequent (deviant) and frequent (standard) stimuli irrelevant to the ongoing task. In the present study, we used human faces expressing different emotions as deviants and standards. In such studies, participants perform various tasks, so their attention is diverted from the vMMN-related stimuli. If such tasks vary in their attentional demand, they might influence the outcome of vMMN studies. In this study, we compared four kinds of frequently used tasks: (1) a tracking task that demanded continuous performance, (2) a detection task where the target stimuli appeared at any time, (3) a detection task where target stimuli appeared only in the inter-stimulus intervals, and (4) a task where target stimuli were members of the stimulus sequence. This fourth task elicited robust vMMN, while in the other three tasks, deviant stimuli elicited moderate posterior negativity (vMMN). We concluded that the ongoing task had a marked influence on vMMN; thus, it is important to consider this effect in vMMN studies.

Continuous dynamics in behavior reveal interactions between perceptual warping in categorization and speech-in-noise perception.

Spoken language comprehension requires listeners map continuous features of the speech signal to discrete category labels. Categories are however malleable to surrounding context and stimulus precedence; listeners' percept can dynamically shift depending on the sequencing of adjacent stimuli resulting in a warping of the heard phonetic category. Here, we investigated whether such perceptual warping-which amplify categorical hearing-might alter speech processing in noise-degraded listening scenarios. We measured continuous dynamics in perception and category judgments of an acoustic-phonetic vowel gradient via mouse tracking. Tokens were presented in serial vs. random orders to induce more/less perceptual warping while listeners categorized continua in clean and noise conditions. Listeners' responses were faster and their mouse trajectories closer to the ultimate behavioral selection (marked visually on the screen) in serial vs. random order, suggesting increased perceptual attraction to category exemplars. Interestingly, order effects emerged earlier and persisted later in the trial time course when categorizing speech in noise. These data describe interactions between perceptual warping in categorization and speech-in-noise perception: warping strengthens the behavioral attraction to relevant speech categories, making listeners more decisive (though not necessarily more accurate) in their decisions of both clean and noise-degraded speech.

A DNA Finite-State Machine Based on the Programmable Allosteric Strategy of DNAzyme.

Living organisms can produce corresponding functions by responding to external and internal stimuli, and this irritability plays a pivotal role in nature. Inspired by such natural temporal responses, the development and design of nanodevices with the ability to process time-related information could facilitate the development of molecular information processing systems. Here, we proposed a DNA finite-state machine that can dynamically respond to sequential stimuli signals. To build this state machine, a programmable allosteric strategy of DNAzyme was developed. This strategy performs the programmable control of DNAzyme conformation using a reconfigurable DNA hairpin. Based on this strategy, we first implemented a finite-state machine with two states. Through the modular design of the strategy, we further realized the finite-state machine with five states. The DNA finite-state machine endows molecular information systems with the ability of reversible logic control and order detection, which can be extended to more complex DNA computing and nanomachines to promote the development of dynamic nanotechnology.

Parallel Acquisition of Uncorrelated Sequences does Not Provide Firm Evidence for a Modular Sequence-Learning System.

Dual-systems theories of sequence learning assume that sequence learning may proceed within a unidimensional learning system that is immune to cross-dimensional interference because information is processed and represented in dimension-specific, encapsulated modules. Important evidence for such modularity comes from studies investigating the absence or presence of interference between multiple uncorrelated sequences (e.g., a sequence of color stimuli and a sequence of motor keypresses). Here we question the premise that the parallel acquisition of uncorrelated sequences provides convincing evidence for a modularized learning system. In contrast, we demonstrate that parallel acquisition of multiple uncorrelated sequences is well predicted by a computational model that assumes a single learning system with joint representations of stimulus and response features.

Individual differences could explain the failure in transitive inference formation in pigeons using probabilistic reinforcement.

In propositional logic, it is stated that "for if A is predicated for every B, and B for every C, A must necessarily be predicated of every C". Following a similar logical process, it can be said that If A > B and B > C, then A > C, this is called transitive inference (TI). Piaget developed a verbal task to evaluate TI in children. Subsequent studies adapted this task for animals using a conditioned discrimination between five-terms sequence of stimuli A + B-, B + C-, C + D-, and D + E-. If subjects prefer B over D during test, it is assumed that TI has occurred. In this experiment, we analyzed the effects of task complexity on TI by using a five-terms sequence of stimuli associated with probabilistic outcomes during training, in pigeons. Thus, both stimuli are reinforced in each pair but with different probability, 0.8 for + stimulus and 0.2 for the-stimulus. We found that performance during C + D- pair is impaired and preference in the test pair BD is affected. However, this impairment is dependent on individual differences in performance in C + D- pair. We compare our findings with previous research and conclude that Pavlovian mechanisms, as well as ordering of stimuli, can account for our findings.

The Use of Heart Rate Responses Extracted From Functional Near-Infrared Spectroscopy Data as a Measure of Speech Discrimination Ability in Sleeping Infants.

Cardiac responses (e.g., heart rate changes) due to an autonomous response to sensory stimuli have been reported in several studies. This study investigated whether heart rate information extracted from functional near-infrared spectroscopy (fNIRS) data can be used to assess the discrimination of speech sounds in sleeping infants. This study also investigated the adaptation of the heart rate response over multiple, sequential stimulus presentations. fNIRS data were recorded from 23 infants with no known hearing loss, aged 2 to 10 months. Speech syllables were presented using a habituation/dishabituation test paradigm: the infant's heart rate response was first habituated by repeating blocks of one speech sound; then, the heart rate response was dishabituated with the contrasting (novel) speech sound. This stimulus presentation sequence was repeated for as long as the infants were asleep. The group-level average heart rate response to the novel stimulus was greater than that to the habituated first sound, indicating that sleeping infants were able to discriminate the speech sound contrast. A significant adaptation of the heart rate responses was seen over the session duration. The dishabituation response could be a valuable marker for speech discrimination, especially when used in conjunction with the fNIRS hemodynamic response.

Real-time Bayesian Control of Reactive Brain Computer Interfaces

This paper introduces an improved method for real-time brain computer interface control. We demonstrate how Bayesian optimization and feedback can be used to achieve faster statistical convergence by controlling the sequence of stimuli shown in a brain computer interface based on a visual oddball paradigm.

Can Vestibular-Evoked Myogenic Potentials Be Used in the Assessment of Reflex habituation? a Preliminary Report

Background: Vestibular-evoked myogenic potentials (VEMPs) provide an electrophysiological evaluation of vestibular reflexes. The aim of the study was to search for the habituation of ocular and cervical VEMPs (cVEMPs). Materials and Methods: A total of 20 healthy volunteers (10 men and 10 women), with a mean age of 32.4 years (range: 25–45 years) were included in the study. cVEMP and ocular VEMP (oVEMP) tests were performed using “click stimuli.” In cVEMP and oVEMP tests, the latency and amplitude of the responses recorded with 100 and 250 stimulus sequences were compared. Results: When the traces recorded with 100 repetitions for both tests were compared with the traces obtained with 250 repetitions, it was observed that the latencies increased while the amplitudes decreased with increasing number of stimuli, which was statistically significant. Conclusion: Our results showed that an increase in the number of stimuli in oVEMP and cVEMP tests in healthy individuals led to a decrease in amplitude and an increase in latency. As noninvasive, short, and inexpensive evaluation methods, VEMP tests may be used in evaluating the “habituation response” and may find new areas of investigation.

Investigating interactions between types of order in categorization

This study simultaneously manipulates within-category (rule-based vs. similarity-based), between-category (blocked vs. interleaved), and across-blocks (constant vs. variable) orders to investigate how different types of presentation order interact with one another. With regard to within-category orders, stimuli were presented either in a “rule plus exceptions” fashion (in the rule-based order) or by maximizing the similarity between contiguous examples (in the similarity-based order). As for the between-category manipulation, categories were either blocked (in the blocked order) or alternated (in the interleaved order). Finally, the sequence of stimuli was either repeated (in the constant order) or varied (in the variable order) across blocks. This research offers a novel approach through both an individual and concurrent analysis of the studied factors, with the investigation of across-blocks manipulations being unprecedented. We found a significant interaction between within-category and across-blocks orders, as well as between between-category and across-blocks orders. In particular, the combination similarity-based + variable orders was the most detrimental, whereas the combination blocked + constant was the most beneficial. We also found a main effect of across-blocks manipulation, with faster learning in the constant order as compared to the variable one. With regard to the classification of novel stimuli, learners in the rule-based and interleaved orders showed generalization patterns that were more consistent with a specific rule-based strategy, as compared to learners in the similarity-based and blocked orders, respectively. This study shows that different types of order can interact in a subtle fashion and thus should not be considered in isolation.

Temporal dependencies in sequences of perceptual learning stimuli impact choice behavior in Gabor orientation discrimination task

Temporal dependencies in sequences of perceptual learning stimuli impact choice behavior in Gabor orientation discrimination task