scholarly journals Multisensory stimuli shift perceptual priors to facilitate rapid behavior

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
John Plass ◽  
David Brang
Keyword(s):  
Cortical Excitability ◽  
Reaction Times ◽  
Stimulus Onset ◽  
Stimulus Sequence ◽  
Phase Resetting ◽  
Redundant Target Effect ◽  
Sequence Effects ◽  
Multisensory Interactions ◽  
Sensory Responses ◽  
Target Effect

AbstractMultisensory stimuli speed behavioral responses, but the mechanisms subserving these effects remain disputed. Historically, the observation that multisensory reaction times (RTs) outpace models assuming independent sensory channels has been taken as evidence for multisensory integration (the “redundant target effect”; RTE). However, this interpretation has been challenged by alternative explanations based on stimulus sequence effects, RT variability, and/or negative correlations in unisensory processing. To clarify the mechanisms subserving the RTE, we collected RTs from 78 undergraduates in a multisensory simple RT task. Based on previous neurophysiological findings, we hypothesized that the RTE was unlikely to reflect these alternative mechanisms, and more likely reflected pre-potentiation of sensory responses through crossmodal phase-resetting. Contrary to accounts based on stimulus sequence effects, we found that preceding stimuli explained only 3–9% of the variance in apparent RTEs. Comparing three plausible evidence accumulator models, we found that multisensory RT distributions were best explained by increased sensory evidence at stimulus onset. Because crossmodal phase-resetting increases cortical excitability before sensory input arrives, these results are consistent with a mechanism based on pre-potentiation through phase-resetting. Mathematically, this model entails increasing the prior log-odds of stimulus presence, providing a potential link between neurophysiological, behavioral, and computational accounts of multisensory interactions.

scholarly journals Multisensory Stimuli Shift Perceptual Priors to Favor Rapid Detection

2021 ◽  
Author(s):  
John Plass ◽  
David Brang
Keyword(s):  
Cortical Excitability ◽  
Reaction Times ◽  
Stimulus Onset ◽  
Stimulus Sequence ◽  
Phase Resetting ◽  
Redundant Target Effect ◽  
Sequence Effects ◽  
Multisensory Interactions ◽  
Sensory Responses ◽  
Target Effect

Multisensory stimuli speed behavioral responses, but the mechanisms subserving these effects remain disputed. Historically, the observation that multisensory reaction times (RTs) outpace models assuming independent sensory channels has been taken as evidence for multisensory integration (the “redundant target effect”; RTE). However, this interpretation has been challenged by alternative explanations based on stimulus sequence effects, RT variability, and/or negative correlations in unisensory processing. To clarify the mechanisms subserving the RTE, we collected RTs from 78 undergraduates in a multisensory simple RT task. Based on previous neurophysiological findings, we hypothesized that the RTE was unlikely to reflect these alternative mechanisms, and more likely reflected pre-potentiation of sensory responses through crossmodal phase-resetting. Contrary to accounts based on stimulus sequence effects, we found that preceding stimuli explained only 3-9% of the variance in apparent RTEs. Comparing three plausible evidence accumulator models, we found that multisensory RT distributions were best explained by increased sensory evidence at stimulus onset. Because crossmodal phase-resetting increases cortical excitability before sensory input arrives, these results are consistent with a mechanism based on pre-potentiation through phase-resetting. Mathematically, this model entails increasing the prior log-odds of stimulus presence, providing a potential link between neurophysiological, behavioral, and computational accounts of multisensory interactions.

Central Visual Persistence as Measured by the Redundant Target Effect

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 259-259 ◽  
Author(s):  
C A Marzi ◽  
G Nitro ◽  
M Prior
Keyword(s):  
Evoked Potential ◽  
Normal Subjects ◽  
Stimulus Onset ◽  
Visual Persistence ◽  
Single Stimulus ◽  
Redundant Target ◽  
Redundant Target Effect ◽  
Speed Of Response ◽  
Target Effect ◽  
Onset Asynchrony

We measured the duration of central visual persistence by testing normal subjects for the redundant target effect (RTE), ie the speeding up of reaction time to redundant visual stimuli in comparison to similar single stimuli. Brief LED-generated flashes were presented to normal subjects either singly or in a pair at peripheral visual field locations (5 or 30 deg along the horizontal meridian). Stimulus pairs could appear either in the same hemifield at different locations or in opposite hemifields with a stimulus onset asynchrony (SOA) ranging between 0 and 100 ms. The subject's task was to press a key as soon as possible following the appearance of either a single stimulus or of the first stimulus in a pair. We found a robust and consistent overall RTE with double stimuli yielding faster RTs than single stimuli for both intrafield and interfield presentations. The effect decreased significantly from 0 ms to 40 ms SOA and at longer SOAs the speed of response to stimulus pairs was indistinguishable from that to a single stimulus. We believe that the longest SOA compatible with a reliable RTE (40 ms) reflects the duration of central persistence. Evoked-potential evidence gathered in our laboratory suggests that the locus of such persistence may be the extrastriate visual cortex.

scholarly journals TMS of V1 eliminates unconscious processing of chromatic stimuli

2019 ◽  
Author(s):  
Mikko Hurme ◽  
Mika Koivisto ◽  
Linda Henriksson ◽  
Henry Railo
Keyword(s):  
Reaction Times ◽  
The Unconscious ◽  
Unconscious Processing ◽  
Metacontrast Masking ◽  
Chromatic Stimulus ◽  
Redundant Target Effect ◽  
Visual Mask ◽  
Neurological Patients ◽  
Target Effect ◽  
Healthy Participants

AbstractSome of the neurological patients with primary visual cortex (V1) lesions can guide their behavior based on stimuli presented to their blind visual field. One example of this phenomenon is the ability to discriminate colors in the absence of awareness. These so-called patients with blindsight must have a neural pathway that bypasses the V1, explaining their ability to unconsciously process stimuli. To test if similar pathways function in neurologically healthy individuals or if unconscious processing depends on the V1, we disturbed the visibility of a chromatic stimulus with metacontrast masking (Experiment 1) or transcranial magnetic stimulation (TMS) of the V1 (Experiment 2). We measured unconscious processing using the redundant target effect (RTE), which is the speeding up of reaction times in response to dual stimuli compared with one stimulus, when the task is to respond to any number of stimuli. An unconscious chromatic RTE was found when the visibility of the redundant chromatic stimulus was suppressed with a visual mask. When TMS was applied to the V1 to disturb the perception of the redundant chromatic stimulus, the RTE was eliminated. Based on our results and converging evidence from previous studies, we conclude that the unconscious processing of chromatic information depends on the V1 in neurologically healthy participants.

Focusing of Visuospatial Attention

2001 ◽  
Vol 15 (4) ◽  
pp. 256-274 ◽  
Author(s):  
Caterina Pesce ◽  
Rainer Bösel
Keyword(s):  
Reaction Times ◽  
Visual Space ◽  
Spatial Relation ◽  
Stimulus Onset ◽  
Visuospatial Attention ◽  
Task Demands ◽  
Time Interval ◽  
Behavioral Studies ◽  
Task Conditions ◽  
Simple Rt

Abstract In the present study we explored the focusing of visuospatial attention in subjects practicing and not practicing activities with high attentional demands. Similar to the studies of Castiello and Umiltà (e. g., 1990) , our experimental procedure was a variation of Posner's (1980) basic paradigm for exploring covert orienting of visuospatial attention. In a simple RT-task, a peripheral cue of varying size was presented unilaterally or bilaterally from a central fixation point and followed by a target at different stimulus-onset-asynchronies (SOAs). The target could occur validly inside the cue or invalidly outside the cue with varying spatial relation to its boundary. Event-related brain potentials (ERPs) and reaction times (RTs) were recorded to target stimuli under the different task conditions. RT and ERP findings showed converging aspects as well as dissociations. Electrophysiological results revealed an amplitude modulation of the ERPs in the early and late Nd time interval at both anterior and posterior scalp sites, which seems to be related to the effects of peripheral informative cues as well as to the attentional expertise. Results were: (1) shorter latency effects confirm the positive-going amplitude enhancement elicited by unilateral peripheral cues and strengthen the criticism against the neutrality of spatially nonpredictive peripheral cueing of all possible target locations which is often presumed in behavioral studies. (2) Longer latency effects show that subjects with attentional expertise modulate the distribution of the attentional resources in the visual space differently than nonexperienced subjects. Skilled practice may lead to minimizing attentional costs by automatizing the use of a span of attention that is adapted to the most frequent task demands and endogenously increases the allocation of resources to cope with less usual attending conditions.

scholarly journals Giving Subjects the Eye and Showing Them the Finger: Socio-Biological Cues and Saccade Generation in the Anti-Saccade Task

Perception ◽  
10.1068/p7085 ◽  
2012 ◽  
Vol 41 (2) ◽  
pp. 131-147 ◽  
Author(s):  
Nicola J Gregory ◽  
Timothy L Hodgson
Keyword(s):  
Opposite Direction ◽  
Reaction Times ◽  
Oculomotor System ◽  
Short Soas ◽  
Stimulus Onset ◽  
Saccade Direction ◽  
Saccade Task ◽  
Saccadic Reaction Times ◽  
Saccadic Responses ◽  
Gaze Cues

Pointing with the eyes or the finger occurs frequently in social interaction to indicate direction of attention and one's intentions. Research with a voluntary saccade task (where saccade direction is instructed by the colour of a fixation point) suggested that gaze cues automatically activate the oculomotor system, but non-biological cues, like arrows, do not. However, other work has failed to support the claim that gaze cues are special. In the current research we introduced biological and non-biological cues into the anti-saccade task, using a range of stimulus onset asynchronies (SOAs). The anti-saccade task recruits both top–down and bottom–up attentional mechanisms, as occurs in naturalistic saccadic behaviour. In experiment 1 gaze, but not arrows, facilitated saccadic reaction times (SRTs) in the opposite direction to the cues over all SOAs, whereas in experiment 2 directional word cues had no effect on saccades. In experiment 3 finger pointing cues caused reduced SRTs in the opposite direction to the cues at short SOAs. These findings suggest that biological cues automatically recruit the oculomotor system whereas non-biological cues do not. Furthermore, the anti-saccade task set appears to facilitate saccadic responses in the opposite direction to the cues.

Longitudinal imaging of VIP interneurons reveals sup-population specific effects of stroke that can be rescued with chemogenetic therapy

2021 ◽  
Author(s):  
Mohamad Motaharinia ◽  
Kimberly Gerrow ◽  
Roobina Boghozian ◽  
Emily White ◽  
Sun-Eui Choi ◽  
...  
Keyword(s):  
Calcium Imaging ◽  
Cortical Excitability ◽  
Sensory Response ◽  
Inhibitory Interneurons ◽  
Partial Recovery ◽  
Highly Active ◽  
Specific Effects ◽  
Somatosensory Responses ◽  
Sensory Responses ◽  
Longitudinal Imaging

Abstract Stroke profoundly disrupts cortical excitability which impedes recovery, but how it affects the function of specific inhibitory interneurons, or subpopulations therein, is poorly understood. Interneurons expressing vasoactive intestinal peptide (VIP) represent an intriguing stroke target because they can regulate cortical excitability through disinhibition. Here we chemogenetically augmented VIP interneuron excitability after stroke to show that it enhances somatosensory responses and improves recovery of paw function. Using longitudinal calcium imaging, we discovered that stroke primarily disrupts the fidelity (fraction of responsive trials) and predictability of sensory responses within a subset of highly active VIP neurons. Partial recovery of responses occurred largely within these active neurons and was not accompanied by the recruitment of minimally active neurons. Importantly, chemogenetic stimulation preserved sensory response fidelity and predictability in highly active neurons. These findings provide a new depth of understanding into how stroke and prospective therapies (chemogenetics), can influence subpopulations of inhibitory interneurons.

scholarly journals The Efficacy of Single-Trial Multisensory Memories

2013 ◽  
Vol 26 (5) ◽  
pp. 483-502 ◽  
Author(s):  
Antonia Thelen ◽  
Micah M. Murray
Keyword(s):  
Object Recognition ◽  
Brain Activity ◽  
Memory Performance ◽  
Stimulus Onset ◽  
Object Representations ◽  
Single Trial ◽  
Multisensory Interactions ◽  
Early Processing ◽  
Opposing Effects ◽  
Task Irrelevant

This review article summarizes evidence that multisensory experiences at one point in time have long-lasting effects on subsequent unisensory visual and auditory object recognition. The efficacy of single-trial exposure to task-irrelevant multisensory events is its ability to modulate memory performance and brain activity to unisensory components of these events presented later in time. Object recognition (either visual or auditory) is enhanced if the initial multisensory experience had been semantically congruent and can be impaired if this multisensory pairing was either semantically incongruent or entailed meaningless information in the task-irrelevant modality, when compared to objects encountered exclusively in a unisensory context. Processes active during encoding cannot straightforwardly explain these effects; performance on all initial presentations was indistinguishable despite leading to opposing effects with stimulus repetitions. Brain responses to unisensory stimulus repetitions differ during early processing stages (∼100 ms post-stimulus onset) according to whether or not they had been initially paired in a multisensory context. Plus, the network exhibiting differential responses varies according to whether or not memory performance is enhanced or impaired. The collective findings we review indicate that multisensory associations formedviasingle-trial learning exert influences on later unisensory processing to promote distinct object representations that manifest as differentiable brain networks whose activity is correlated with memory performance. These influences occur incidentally, despite many intervening stimuli, and are distinguishable from the encoding/learning processes during the formation of the multisensory associations. The consequences of multisensory interactions thus persist over time to impact memory retrieval and object discrimination.

Tussen Lezen En Luisteren

1992 ◽  
Vol 43 ◽  
pp. 27-38
Author(s):  
Ton Dijkstra
Keyword(s):  
Stimulus Onset Asynchrony ◽  
Divided Attention ◽  
Single Channel ◽  
Reaction Times ◽  
Race Model ◽  
Stimulus Onset ◽  
Sublexical Processing ◽  
Temporal Aspects ◽  
Onset Asynchrony ◽  
Processing Differences

Two divided attention experiments investigated whether graphemes and phonemes can mutually activate each other during bimodal sublexical processing. Dutch subjects reacted to target letters and/or speech sounds in single-channel and bimodal stimuli. In some bimodal conditions, the visual and auditory targets were congruent (e.g., visual A, auditory /a:/), in others they were not (e.g., visual U, auditory /a:/). Temporal aspects of cross-modal activation were examined by varying the stimulus onset asynchrony (SOA) of visual and auditory stimulus components. Processing differences among stimuli (e.g., the letters A and U) were accounted for by correcting the obtained bimodal reaction times by means of the predictions of an independent race-model. Comparing the results of the adapted congruent and incongruent conditions for each SOA, it can be concluded that (a) cross-modal activation takes place in this task situation; (b) it is bidirectional, i.e. it spreads from grapheme to phoneme and vice versa; and (c) it occurs very rapidly.

Sounds prevent selective monitoring of high spatial frequency channels in vision

2012 ◽  
Vol 25 (0) ◽  
pp. 40
Author(s):  
Alexis Pérez-Bellido ◽  
Joan López-Moliner ◽  
Salvador Soto-Faraco
Keyword(s):  
Standard Deviation ◽  
Spatial Frequency ◽  
Visual Processing ◽  
Reaction Times ◽  
High Spatial Frequency ◽  
Visual Signals ◽  
Sensory Interactions ◽  
Multisensory Interactions ◽  
Visual Targets ◽  
Selective Monitoring

Prior knowledge about the spatial frequency (SF) of upcoming visual targets (Gabor patches) speeds up average reaction times and decreases standard deviation. This has often been regarded as evidence for a multichannel processing of SF in vision. Multisensory research, on the other hand, has often reported the existence of sensory interactions between auditory and visual signals. These interactions result in enhancements in visual processing, leading to lower sensory thresholds and/or more precise visual estimates. However, little is known about how multisensory interactions may affect the uncertainty regarding visual SF. We conducted a reaction time study in which we manipulated the uncertanty about SF (SF was blocked or interleaved across trials) of visual targets, and compared visual only versus audio–visual presentations. Surprisingly, the analysis of the reaction times and their standard deviation revealed an impairment of the selective monitoring of the SF channel by the presence of a concurrent sound. Moreover, this impairment was especially pronounced when the relevant channels were high SFs at high visual contrasts. We propose that an accessory sound automatically favours visual processing of low SFs through the magnocellular channels, thereby detracting from the potential benefits from tuning into high SF psychophysical-channels.

Chronic Suppression of Activity in Barrel Field Cortex Downregulates Sensory Responses in Contralateral Barrel Field Cortex

2005 ◽  
Vol 94 (5) ◽  
pp. 3342-3356 ◽  
Author(s):  
Lu Li ◽  
V. Rema ◽  
Ford F. Ebner
Keyword(s):  
Barrel Cortex ◽  
Cortical Excitability ◽  
Single Cells ◽  
Cortical Function ◽  
Adult Rats ◽  
Strong Suppression ◽  
Barrel Field ◽  
Layer V ◽  
Sensory Responses ◽  
Prominent Response

Numerous lines of evidence indicate that neural information is exchanged between the cerebral hemispheres via the corpus callosum. Unilateral ablation lesions of barrel field cortex (BFC) in adult rats induce strong suppression of background and evoked activity in the contralateral barrel cortex and significantly delay the onset of experience-dependent plasticity. The present experiments were designed to clarify the basis for these interhemispheric effects. One possibility is that degenerative events, triggered by the lesion, degrade contralateral cortical function. Another hypothesis, alone or in combination with degeneration, is that the absence of interhemispheric activity after the lesion suppresses contralateral responsiveness. The latter hypothesis was tested by placing an Alzet minipump subcutaneously and connecting it via a delivery tube to a cannula implanted over BFC. The minipump released muscimol, a GABAA receptor agonist at a rate of 1 μl/h, onto one barrel field cortex for 7 days. Then with the pump still in place, single cells were recorded in the contralateral BFC under urethan anesthesia. The data show a ∼50% reduction in principal whisker responses (D2) compared with controls, with similar reductions in responses to the D1 and D3 surround whiskers. Despite these reductions, spontaneous firing is unaffected. Fast spiking units are more sensitive to muscimol application than regular spiking units in both the response magnitude and the center/surround ratio. Effects of muscimol are also layer specific. Layer II/III and layer IV neurons decrease their responses significantly, unlike layer V neurons that fail to show significant deficits. The results indicate that reduced activity in one hemisphere alters cortical excitability in the other hemisphere in a complex manner. Surprisingly, a prominent response decrement occurs in the short-latency (3–10 ms) component of principal whisker responses, suggesting that suppression may spread to neurons dominated by thalamocortical inputs after interhemispheric connections are inactivated. Bilateral neurological impairments have been described after unilateral stroke lesions in the clinical literature.

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