Simultaneous Presentation Of Stimuli Research Articles

Using a mixed-reality headset to elicit and track clinically relevant movement in the clinic.

21st century neurology will require scalable and quantitative tools that can improve neurologic evaluations over telehealth and expand access to care. Commercially available mixed-reality headsets allow for simultaneous presentation of stimuli via holograms projected into the real world and objective and quantitative measurement of hand movement, eye movement, and phonation. We created 6 tasks designed to mimic standard neurologic assessments and administered them to a single participant via the Microsoft HoloLens 2 mixed-reality headset. The tasks assessed postural hand tremor, finger tapping, pronation and supination of hands, hand and eye tracking of a center-out task, hand and eye tracking of a random motion task, and vocal assessment. We show the utility of the HoloLens for commonly used neurological exams. First, we demonstrate that headset-derived holograms can project hand movements and objects in 3D space, providing a method to accurately and reproducibly present test stimuli to reduce test-test variability. Second, we found that participant hand movements closely matched holographic stimuli using a variety of metrics calculated on recorded movement data. Third, we showed that the HoloLens can record and playback exam tasks for visual inspection, sharing with other medical providers, and future analysis. Fourth, we showed that vocal recordings and analysis could be used to profile vocal characteristics over time. Together, this demonstrates the versatility of mixed reality headsets and possible applications for neurological assessment. Administering components of the neurologic exam via a self-contained and commercially available mixed-reality headset has numerous benefits including detailed kinematic quantification, reproducible stimuli presentation from test to test, and can be self-administered expanding access to neurological care and saving hospital time and money. This work was supported by grants from the National Institutes of Health (NIH) (F30AG063468) (E.L.), (F31NS113395) (D.J.C), and the Pilot Grant Award from the University of Colorado Movement Disorders Center (D.J.C).

Частотно-зависимый эффект транскраниальной стимуляции тета-вспышками префронтальной коры на когнитивные функции

Theta-burst stimulation (TBS) is widely used due to induction of the long-lasting effects with short protocol duration. To reduce the variability of the effect, approaches to personalize it, such as using theta-gamma coupling frequencies (TGC), are being investigated. The study was aimed to develop the personalized protocol of navigated intermittent theta-burst stimulation (iTBS-ind) based on TGC, and to compare this protocol with the standard one (iTBS-5/50) and sham stimulation (iTBS-sham). The study involved 16 healthy volunteers (М — 7; 29.6 years), who were randomized to receive one session of each protocol of the left dorsolateral prefrontal cortex iTBS. The effects were estimated using the n-back test with simultaneous presentation of verbal and spatial stimuli (n = 2, 3), Digit Span test, Corsi blocks task, Tower of London test; testing was performed immediately before, immediately after and 60 min after stimulation. No severe adverse events were reported. Significant effect was obtained when performing assessment after 60 min for iTBS-5/50 in the n-back test with spatial stimuli (n = 3) (pcorr = 0.018), for all protocols in the Tower of London test (pcorr = 0.039 for iTBS-5/50, pcorr = 0.045 for iTBS-ind, pcorr = 0.003 for iTBS-sham). The iTBS-5/50 effect was significantly higher compared to iTBS-sham in the spatial n-back test (n = 3) (pcorr = 0.039), but lower compared to iTBS-ind and iTBS-sham in the Corsi blocks task (pcorr = 0.038 and 0.048, respectively). Thus, we failed to confirm the personalized protocol efficacy and superiority to the standard protocol and sham stimulation. Considering the effect of standard protocol, its further investigation can be promising.

A Treatment Evaluation of Successive and Simultaneous Visual Stimulus Presentation During Tact Training with Children with Autism

A Treatment Evaluation of Successive and Simultaneous Visual Stimulus Presentation During Tact Training with Children with Autism

Event-Related Desynchronization of MEG Alpha-Band Oscillations during Simultaneous Presentation of Audio and Visual Stimuli in Children with Autism Spectrum Disorder.

Alpha-band (8-12 Hz) event-related desynchronization (ERD) or a decrease in alpha power in electro- and magnetoencephalography (EEG and MEG) reflects the involvement of a neural tissue in information processing. It is known that most children with autism spectrum disorder (ASD) have difficulties in information processing, and, thus, investigation of alpha oscillations is of particular interest in this population. Previous studies have demonstrated alterations in this neural activity in individuals with ASD; however, little is known about alpha ERD during simultaneous presentation of auditory and visual stimuli in children with and without ASD. As alpha oscillations are intimately related to attention, and attention deficit is one of the common co-occurring conditions of ASD, we predict that children with ASD can have altered alpha ERD in one of the sensory domains. In the present study, we used MEG to investigate alpha ERD in groups of 20 children with ASD and 20 age-matched typically developing controls. Simple amplitude-modulated tones were presented together with a fixation cross appearing on the screen. The results showed that children with ASD had a bilateral reduction in alpha-band ERD in the auditory but not visual cortex. Moreover, alterations in the auditory cortex were associated with a higher presence of autistic traits measured in behavioral assessment.

Intact high-resolution working memory binding in a patient with developmental amnesia and selective hippocampal damage.

Debate continues regarding the possible role of the hippocampus across short‐term and working memory tasks. The current study examined the possibility of a hippocampal contribution to precise, high‐resolution cognition and conjunctive memory. We administered visual working memory tasks featuring a continuous response component to a well‐established developmental amnesic patient with relatively selective bilateral hippocampal damage (Jon) and healthy controls. The patient was able to produce highly accurate response judgments regarding conjunctions of color and orientation or color and location, using simultaneous or sequential presentation of stimuli, with no evidence of any impairment in working memory binding, categorical accuracy, or continuous precision. These findings indicate that hippocampal damage does not necessarily lead to deficits in high‐resolution cognitive performance, even when the damage is severe and bilateral.

Interocular suppression in primary visual cortex in strabismus: impact of staggering the presentation of stimuli to the eyes.

Diplopia (double vision) in strabismus is prevented by suppression of the image emanating from one eye. In a recent study conducted in two macaques raised with exotropia (an outward ocular deviation) but having normal acuity in each eye, simultaneous display of stimuli to each eye did not induce suppression in V1 neurons. Puzzled by this negative result, we have modified our protocol to display stimuli in a staggered sequence, rather than simultaneously. Additional recordings were made in the same two macaques, following two paradigms. In trial type 1, the receptive field in one eye was stimulated with a sine-wave grating while the other eye was occluded. After 5 s, the occluder was removed and the neuron was stimulated for another 5 s. The effect of uncovering the eye, which potentially exposed the animal to diplopia, was quantified by the peripheral retinal interaction index (PRII). In trial type 2, the receptive field in the fixating eye was stimulated with a grating during binocular viewing. After 5 s, a second grating appeared in the receptive field of the nonfixating eye. The impact of the second grating, which had the potential to generate visual confusion, was quantified by the receptive field interaction index (RFII). For 82 units, the mean PRII was 0.48 ± 0.05 (0.50 = no suppression) and the mean RFII was 0.46 ± 0.08 (0.50 = no suppression). These values suggest mild suppression, but the modest decline in spike rate registered during the second epoch of visual stimulation might have been due to neuronal adaptation, rather than interocular suppression. In a few instances neurons showed unequivocal suppression, but overall, these recordings did not support the contention that staggered stimulus presentation is more effective than simultaneous stimulus presentation at evoking interocular suppression in V1 neurons.NEW & NOTEWORTHY In strabismus, double vision is prevented by interocular suppression. It has been reported that inhibition of neuronal firing in the primary visual cortex occurs only when stimuli are presented sequentially, rather than simultaneously. However, these recordings in alert macaques raised with exotropia showed, with rare exceptions, little evidence to support the concept that staggered stimulus presentation is more effective at inducing interocular suppression of V1 neurons.

Central Nervous System Responses to Comfortable Thermal Stimuli to the Soles of the Feet with Simultaneous Presentation of Other Sensory Stimuli

Central Nervous System Responses to Comfortable Thermal Stimuli to the Soles of the Feet with Simultaneous Presentation of Other Sensory Stimuli

Formation and Retrieval of Associative Memory for a Complex Signal in Mice: Specific Involvement of Hippocampal Field CA1 Neurons

Most important events in the environment are complex in sensory terms. Integration of multimodal information relating to such complex signals by the brain is regarded by many investigators as a biological function of very early forms of consciousness. We report here use of a model of associative learning in mice in which electrocutaneous stimulation was combined with a complex conditioned signal consisting of simultaneous presentation of light and sound stimuli. These studies showed that mice successfully learned and formed long-term memory in a task consisting of conditioned reflex freezing in response to a complex conditioned stimulus. Immunohistochemical mapping of the neuronal expression of the c-fos gene in the hippocampus and associative retrosplenial cortex was performed to study the neural substrates of this memory. We found that only hippocampal field CA1 and not other areas of the hippocampus or the retrosplenial cortex underwent activation on retrieval of the associative memory for the complex conditioned signal, while its components produced no hippocampal activation. In addition, field CA1 showed a strong positive correlation between the level of freezing on retrieval of the memory and the number of neurons activated by retrieval of the memory. Thus, it can be suggested that hippocampal field CA1 is specifically involved in forming and retrieving associative memory for complex signals in the natural environment.

Socially-relevant Visual Stimulation Modulates Physiological Response to Affective Touch in Human Infants

The human tactile system is known to discriminate different types of touches, one of these termed ‘affective touch’, is mainly mediated by slow conducting tactile afferents (CT fibres), which are preferentially activated by slow and gentle strokes.Human infants experience self-generated tactile stimulation during prenatal life, and they receive a large amount of affectionate touches by their caregivers from birth. This early and extended experience with tactile stimulation may likely make infants particularly sensitive to affective touch, and increasing evidence shows that this may indeed be the case. However, infants commonly experience affective touch in the context of social interactions with familiar adults (e.g., while looking at their caregiver), and recent evidence suggests that this helps them assigning affiliative and communicative meaning to the touch they are perceiving. Here we investigated the presence of visual-tactile interactions in 4–5-month-old infants’ physiological (i.e., skin conductance) and behavioural (i.e., visual looking times) responses to visual and tactile stimulation of affective/social nature when the sources of both stimulation are not familiar to the infant. To explore whether the modulation of physiological arousal elicited by the socially-relevant bimodal stimulation is specific to infants or extends into adulthood, we also tested a group of adults. Infants (N = 25) and adults (N = 25) were stimulated on their forearm through slow stroking (i.e. affective touch) or tapping (i.e. non-affective touch) during the observation of dynamic images of socially-relevant (i.e., an unfamiliar face) and non-socially-relevant (i.e., a house) stimuli. We found that the simultaneous presentation of socially-relevant visual-tactile stimuli significantly decreased infants’ – but not the adults’ – electrodermal response, suggesting that infants easily integrate low-level properties of affective touch with socially salient visual information, and that social experience may tune and change sensitivity to affective touch across the life-span.

It occurs after all: Attentional bias towards happy faces in the dot-probe task

Many studies have shown that not only threatening but also positive stimuli capture visual attention. However, in the dot-probe task, a common paradigm to assess attention to emotional stimuli, usually no bias towards happy faces occurs. Here, we investigated whether such a bias can occur and, if so, under which conditions. In Experiment 1, we investigated whether the bias is contingent on the simultaneous presentation of distractor stimuli with the targets. Participants performed a dot-probe task with either stand-alone targets or targets that were accompanied by distractors. We found an attentional bias towards happy faces that was not moderated by target type. To rule out perceptual low-level confounds as the cause of the bias towards happy faces, Experiments 2a and 2b comprised dot-probe tasks with inverted face cues. No attentional bias towards inverted happy faces occurred. In Experiment 3, we investigated whether a bias towards happy faces is contingent on a social-processing mode. Participants performed a dot-probe task with socially meaningful (schematic faces) or socially meaningless (scrambled schematic faces) targets. Again, a bias towards happy faces, which was not moderated by target type, occurred. In Experiment 4, we investigated the attentional bias towards happy faces when another highly relevant expression was present. Participants performed a dot-probe task with both happy and angry face cues. A significant attentional bias towards emotional faces occurred that did not differ between both cue emotions. These results suggest that happy faces are sufficiently relevant for observers to capture attention in the dot-probe task.

Combining Stimulus Fading with Simultaneous Stimulus Presentation in a School Setting for Food Selectivity in a Child with Autism Spectrum Disorder

The participant was a boy diagnosed with autism spectrum disorder (ASD) who displayed severe food selectivity, which raised concerns about imbalanced nutrient consumption. The intervention used combined stimulus fading with simultaneous stimulus presentation without escape extinction (EE) and was implemented by teachers in a school setting. In intervention I, which used only stimulus fade-in of non-preferred foods, favorable results were not obtained. In intervention II, simultaneous stimulus presentation of a preferred food combined with stimulus fade-in of non-preferred foods, Silva’s consumption was stabilized at 100% consumption of three non-preferred foods. When intervention II was terminated, the child’s mother requested the inclusion of two additional non-preferred foods, so the intervention was extended based on a fading protocol planned with and to be used by the mother. The effects of the intervention were maintained at the 3-month post-intervention follow-up. The child’s parents and teachers showed high acceptance of this intervention. The current study offers further evidence that combining antecedent-based interventions without EE has the potential to yield favorable results with some children.

Visual objects interact differently during encoding and memory maintenance.

The storage mechanisms of working memory are the matter of an ongoing debate. The sensory recruitment hypothesis states that memory maintenance and perceptual encoding rely on the same neural substrate. This suggests that the same cortical mechanisms that shape object perception also apply to maintained memory content. We tested this prediction using the Direction Illusion, i.e., the mutual repulsion of two concurrently visible motion directions. Participants memorized the directions of two random dot patterns for later recall. In Experiments 1 and 2, we varied the temporal separation of spatially distinct stimuli to manipulate perceptual concurrency, while keeping concurrency within working memory constant. We observed mutual motion repulsion only under simultaneous stimulus presentation, but proactive repulsion and retroactive attraction under immediate stimulus succession. At inter-stimulus intervals of 0.5 and 2 s, however, proactive repulsion vanished, while the retroactive attraction remained. In Experiment 3, we presented both stimuli at the same spatial position and observed a reappearance of the repulsion effect. Our results indicate that the repulsive mechanisms that shape object perception across space fade during the transition from a perceptual representation to a consolidated memory content. This suggests differences in the underlying structure of perceptual and mnemonic representations. The persistence of local interactions, however, indicates different mechanisms of spatially global and local feature interactions.

Arabic digits and spoken number words: Timing modulates the cross-modal numerical distance effect

Moving seamlessly between spoken number words and Arabic digits is common in everyday life. In this study, we systematically investigated the correspondence between auditory number words and visual Arabic digits in adults. Auditory number words and visual Arabic digits were presented concurrently or sequentially and participants had to indicate whether they described the same quantity. We manipulated the stimulus onset asynchronies (SOAs) between the two stimuli (Experiment 1: −500 ms to +500 ms; Experiment 2: −200 ms to +200 ms). In both experiments, we found a significant cross-modal distance effect. This effect was strongest for simultaneous stimulus presentation and decreased with increasing SOAs. Numerical distance emerged as the most consistent significant predictor overall, in particular for simultaneous presentation. However, physical similarity between the stimuli was often a significant predictor of response times in addition to numerical distance, and at longer SOAs, physical similarity between the stimuli was the only significant predictor. This shows that SOA modulates the extent to which participants access quantity representations. Our results thus support the idea that a semantic quantity representation of auditory and visual numerical symbols is activated when participants perform a concurrent matching task, while at longer SOAs participants are more likely to rely on physical similarity between the stimuli. We also investigated whether individual differences in the efficiency of the cross-modal processing were related to differences in mathematical performance. Our results are inconclusive about whether the efficiency of cross-format numerical correspondence is related to mathematical competence in adults.

Habit2: A stand-alone software solution for presenting stimuli and recording infant looking times in order to study infant development.

Many aspects of infant development are assessed using infant looking times to visual and audiovisual stimuli. In this article, we describe a stand-alone software package that allows simultaneous stimulus presentation to infants and recording of their looking times via a keypress by a human observer. The software was developed to run both on 64-bit Intel-based Macs running Mac OS/X 10.10 (Yosemite) or later and on 64-bit Windows 7 and 10. It can present a variety of visual and/or auditory stimuli; is customizable with respect to how trials are initiated, how trial lengths are defined, and the phases of the experiment; and can be used to record looking times online or after the fact, as well as to assess the reliability of coding. The software is freely available at http://habit.ucdavis.edu.

Effects of the Simultaneous Presentation of Corresponding Auditory and Visual Stimuli on Size Variance Perception.

To overcome limitations in perceptual bandwidth, humans condense various features of the environment into summary statistics. Variance constitutes indices that represent diversity within categories and also the reliability of the information regarding that diversity. Studies have shown that humans can efficiently perceive variance for visual stimuli; however, to enhance perception of environments, information about the external world can be obtained from multisensory modalities and integrated. Consequently, this study investigates, through two experiments, whether the precision of variance perception improves when visual information (size) and corresponding auditory information (pitch) are integrated. In Experiment 1, we measured the correspondence between visual size and auditory pitch for each participant by using adjustment measurements. The results showed a linear relationship between size and pitch—that is, the higher the pitch, the smaller the corresponding circle. In Experiment 2, sequences of visual stimuli were presented both with and without linked auditory tones, and the precision of perceived variance in size was measured. We consequently found that synchronized presentation of audio and visual stimuli that have the same variance improves the precision of perceived variance in size when compared with visual-only presentation. This suggests that audiovisual information may be automatically integrated in variance perception.

Impact of brain arousal and time-on-task on autonomic nervous system activity in the wake-sleep transition

BackgroundAutonomic nervous system (ANS) activity has been shown to vary with the state of brain arousal. In a previous study, this association of ANS activity with distinct states of brain arousal was demonstrated using 15-min EEG data, but without directly controlling for possible time-on-task effects. In the current study we examine ANS-activity in fine-graded EEG-vigilance stages (indicating states of brain arousal) during two conditions of a 2-h oddball task while controlling for time-on-task. In addition, we analyze the effect of time-on-task on ANS-activity while holding the level of brain arousal constant.MethodsHeart rate and skin conductance level of healthy participants were recorded during a 2-h EEG with eyes closed under simultaneous presentation of stimuli in an ignored (N = 39) and attended (N = 39) oddball condition. EEG-vigilance stages were classified using the Vigilance Algorithm Leipzig (VIGALL 2.1). The time-on-task effect was tested by dividing the EEG into four 30-min consecutive time blocks. ANS-activity was compared between EEG-vigilance stages across the entire 2 h and within each time block.ResultsWe found a coherent decline of ANS-activity with declining brain arousal states, over the 2-h recording and in most cases within each 30-min block in both conditions. Furthermore, we found a significant time-on-task effect on heart rate, even when arousal was kept constant. It was most pronounced between the first and all subsequent blocks and could have been a consequence of postural change at the beginning of the experiment.ConclusionOur findings contribute to the validation of VIGALL 2.1 using ANS parameters in 2-h EEG recording under oddball conditions.

The effects of interaural level differences on binaural fusion in normal-hearing listeners

Sound localization is an important aspect of auditory scene analysis, allowing listeners to group acoustic components from the same location into a single stream (Bregman 1990). Binaural pitch fusion, the fusion of different frequency tones across ears, can be thought of as one type of auditory streaming. Little is known about how sound localization cues affect binaural fusion. The goal of this study was to investigate the effects of interaural level differences (ILDs), one cue for sound localization, on binaural fusion of dichotic tones. Binaural pitch fusion was measured in adult normal-hearing (NH) listeners, using five ILD conditions: ILD = 0, 1.25, 2.5, 5, and 10 dB. Fusion ranges were measured by simultaneous presentation of reference and comparison stimuli in opposite ears, and varying the comparison stimulus to find the frequency range that fused with the reference stimulus. Preliminary results (5 NH; data collection is ongoing) show that small ILDs increase fusion ranges, while larger ILDs decrease fusion ranges. These findings suggest that ILDs can affect fusion range in NH listeners, and imply that simulated sound source location may provide a top-down grouping cue for binaural fusion. [This research was funded by a NIH-NIDCD grant R01 DC013307.]Sound localization is an important aspect of auditory scene analysis, allowing listeners to group acoustic components from the same location into a single stream (Bregman 1990). Binaural pitch fusion, the fusion of different frequency tones across ears, can be thought of as one type of auditory streaming. Little is known about how sound localization cues affect binaural fusion. The goal of this study was to investigate the effects of interaural level differences (ILDs), one cue for sound localization, on binaural fusion of dichotic tones. Binaural pitch fusion was measured in adult normal-hearing (NH) listeners, using five ILD conditions: ILD = 0, 1.25, 2.5, 5, and 10 dB. Fusion ranges were measured by simultaneous presentation of reference and comparison stimuli in opposite ears, and varying the comparison stimulus to find the frequency range that fused with the reference stimulus. Preliminary results (5 NH; data collection is ongoing) show that small ILDs increase fusion ranges, while larger ILDs decrea...

Examining Crowding Using a Real Three-Dimensional Experimental Setup

Abstract The phenomenon of impaired recognition of peripherally presented visual targets, when flanked by similar stimuli, is referred to as crowding. Studies in a two-dimensional space have shown that lateral distances are critical: the extent of crowding depends on eccentricity of the target stimulus and on the spacing between target and flanking stimuli. The question of whether also distances in depth affect crowding was until now usually investigated using virtual depth. However, virtual and real depth differ, for example with respect to the accommodation-vergence alignment and to effects of blur. Thus, we made an attempt to study crowding in real depth. In our experimental setup, real depth is implemented by two screens, observed via a semi-transparent mirror. Thus, moving the two screens along the line of sight allows simultaneous stimulus presentation with real depth differences. In a first validation study with 18 participants, a fixation cross was fixed in a depth of 190 cm. Single and flanked Landolt rings were presented in 2° of eccentricity in the same depth as fixation, or in front of (170 cm), or behind (215 cm) the fixation depth. Results concerning recognition performance show a similar extent of crowding for flanked targets presented in front of, or behind the fixation depth, and flanked targets in the fixation depth. But, concerning reaction time, the difference between isolated and flanked targets was reduced in defocused depths compared to the fixation depth. That is, reaction time toward flanked targets in the fixation depth was higher than in front of, or behind the fixation depth. With the experimental setup, crowding successfully was induced in different real depths. In further studies, the influence of target and flankers in divergent depths on crowding will be investigated.

Competitive interactions affect working memory performance for both simultaneous and sequential stimulus presentation

Competition between simultaneously presented visual stimuli lengthens reaction time and reduces both the BOLD response and neural firing. In contrast, conditions of sequential presentation have been assumed to be free from competition. Here we manipulated the spatial proximity of stimuli (Near versus Far conditions) to examine the effects of simultaneous and sequential competition on different measures of working memory (WM) for colour. With simultaneous presentation, the measure of WM precision was significantly lower for Near items, and participants reported the colour of the wrong item more often. These effects were preserved when the second stimulus immediately followed the first, disappeared when they were separated by 500 ms, and were partly recovered (evident for our measure of mis-binding but not WM precision) when the task was altered to encourage participants to maintain the sequentially presented items together in WM. Our results show, for the first time, that competition affects the measure of WM precision, and challenge the assumption that sequential presentation removes competition.

Adaptation in distance perception induced by audio-visual stimuli with spatial disparity

Simultaneous presentation of audio-visual stimuli with disparity leads to perceptual shifts in judgments of the stimulus auditory components (ventriloquism effect, VE). The shifts can persist even to auditory stimuli presented alone (ventriloquism aftereffect, VA). A previous study showed asymmetrical VE and VA for visual adaptors presented closer vs. further than the auditory components [Hladek et al. (2014), Visual calibration of auditory distance perception, ARO #37 Abstract PS-614]. In that study, a brief flash of light (visual adaptor) or noise burst (auditory component) were presented in front of the listener at distances 0.4-2.6 m in a small reverberant room, with visual adaptor 30% closer or further than the auditory component. Here, a new analysis of the results is presented, showing that much of the previously observed asymmetries between the two directions of shift (visual-closer vs. visual-farther) can be accounted for by referencing responses to the pre-adaptation baseline, and by scaling the...