Contextual effects in human visual cortex depend on surface structure

2014 ◽  
Vol 111 (9) ◽  
pp. 1783-1791 ◽  
Author(s):  
Sung Jun Joo ◽  
Scott O. Murray
Keyword(s):  
Visual Cortex ◽  
Surface Structure ◽  
Event Related Potentials ◽  
Contextual Effects ◽  
Orientation Discrimination ◽  
Surround Suppression ◽  
Stimulus Context ◽  
Early Visual Cortex ◽  
Related Potentials ◽  
Local Circuits

Neural responses in early visual cortex depend on stimulus context. One of the most well-established context-dependent effects is orientation-specific surround suppression: the neural response to a stimulus inside the receptive field of a neuron (“target”) is suppressed when it is surrounded by iso-oriented compared with orthogonal stimuli (“flankers”). Despite the importance of orientation-specific surround suppression in potentially mediating a number of important perceptual effects, including saliency, contour integration, and orientation discrimination, the underlying neural mechanisms remain unknown. The suppressive signal could be inherited from precortical areas as early as the retina and thalamus, arise from local circuits through horizontal connections, or be fed back from higher visual cortex. Here, we show, using two different methodologies, measurements of scalp-recorded event-related potentials (ERPs) and behavioral contrast adaptation aftereffects in humans, that orientation-specific surround suppression is dependent on the surface structure in an image. When the target and flankers can be grouped on the same surface (independent of their distance), orientation-specific surround suppression occurs. When the target and flankers are on different surfaces (independent of their distance), orientation-specific surround suppression does not occur. Our results demonstrate a surprising role of high-level, global processes such as grouping in determining when contextual effects occur in early visual cortex.

Orienting and Focusing in Voluntary and Involuntary Visuospatial Attention Conditions

2010 ◽  
Vol 24 (3) ◽  
pp. 198-209 ◽  
Author(s):  
Yan Wang ◽  
Jianhui Wu ◽  
Shimin Fu ◽  
Yuejia Luo
Keyword(s):  
Gain Control ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Orientation Discrimination ◽  
Involuntary Attention ◽  
Attention Condition ◽  
Voluntary Attention ◽  
Visual Spatial ◽  
Related Potentials ◽  
Underlying Mechanisms

In the present study, we used event-related potentials (ERPs) and behavioral measurements in a peripherally cued line-orientation discrimination task to investigate the underlying mechanisms of orienting and focusing in voluntary and involuntary attention conditions. Informative peripheral cue (75% valid) with long stimulus onset asynchrony (SOA) was used in the voluntary attention condition; uninformative peripheral cue (50% valid) with short SOA was used in the involuntary attention condition. Both orienting and focusing were affected by attention type. Results for attention orienting in the voluntary attention condition confirmed the “sensory gain control theory,” as attention enhanced the amplitude of the early ERP components, P1 and N1, without latency changes. In the involuntary attention condition, compared with invalid trials, targets in the valid trials elicited larger and later contralateral P1 components, and smaller and later contralateral N1 components. Furthermore, but only in the voluntary attention condition, targets in the valid trials elicited larger N2 and P3 components than in the invalid trials. Attention focusing in the involuntary attention condition resulted in larger P1 components elicited by targets in small-cue trials compared to large-cue trials, whereas in the voluntary attention condition, larger P1 components were elicited by targets in large-cue trials than in small-cue trials. There was no interaction between orienting and focusing. These results suggest that orienting and focusing of visual-spatial attention are deployed independently regardless of attention type. In addition, the present results provide evidence of dissociation between voluntary and involuntary attention during the same task.

Auditory Mismatch Negativity and P300a Elicited by the “Optimal” Multi-feature Paradigm in Early Schizophrenia

2018 ◽  
Vol 49 (4) ◽  
pp. 238-247 ◽  
Author(s):  
Derek J. Fisher ◽  
Debra J. Campbell ◽  
Shelagh C. Abriel ◽  
Emma M. L. Ells ◽  
Erica D. Rudolph ◽  
...  
Keyword(s):  
Mismatch Negativity ◽  
Early Phase ◽  
Event Related Potentials ◽  
Event Related Potential ◽  
Positive Symptom ◽  
First Episode ◽  
Stimulus Context ◽  
Significant Group ◽  
Related Potentials ◽  
Auditory Change Detection

The mismatch negativity (MMN) is an EEG-derived event-related potential (ERP) elicited by any violation of a predicted auditory “rule,” regardless of whether one is attending to the stimuli and is thought to reflect updating of the stimulus context. Redirection of attention toward a rare, distracting stimulus event, however, can be measured by the subsequent P3a component of the P300. Chronic schizophrenia patients exhibit robust MMN deficits, as well as reductions in P3a amplitude. While, the substantial literature on the MMN in first-episode and early phase schizophrenia in this population reports reduced amplitudes, there also exist several contradictory studies. Conversely, P3a reduction in this population is relatively consistent, although the literature investigating this is small. The primary goal of this study was to contribute to our understanding of whether auditory change detection mechanisms are altered in early phase schizophrenia and, if so, under what conditions. Event-related potentials elicited by duration, frequency, gap, intensity, and location deviants (as elicited by the “optimal” multi-feature paradigm) were recorded in 14 early phase schizophrenia (EP) patients and 17 healthy controls (HCs). Electrical activity was recorded from 15 scalp electrodes. MMN/P3a amplitudes and latencies for each deviant were compared between groups and were correlated with clinical measures in EPs. There were no significant group differences for MMN amplitudes or latencies, though EPs did exhibit reduced P3a amplitudes to gap and duration deviants. Furthermore, PANSS (Positive and Negative Syndrome Scale) positive symptom scores were correlated with intensity MMN latencies and duration P3a amplitudes in EPs. These findings suggest that MMNs may not be as robustly reduced in early phase schizophrenia (relative to chronic illness), but that alterations may be more likely in patients with increased positive symptomatology. Furthermore, these findings offer further support to previous work suggesting that the understudied P3a may have good complementary utility as a marker of early cortical dysfunction in psychosis.

scholarly journals Psychophysiology and Imaging of Visual Cortical Functions in the Blind: A Review

2008 ◽  
Vol 20 (3-4) ◽  
pp. 71-81 ◽  
Author(s):  
Stephanie L. Simon-Dack ◽  
P. Dennis Rodriguez ◽  
Wolfgang A. Teder-Sälejärvi
Keyword(s):  
Visual Cortex ◽  
Transcranial Magnetic Stimulation ◽  
Visual Information ◽  
Magnetic Stimulation ◽  
Late Onset ◽  
Event Related Potentials ◽  
Cortical Activation ◽  
Future Research ◽  
Related Potentials ◽  
Visual Cortical

Imaging, transcranial magnetic stimulation, and psychophysiological recordings of the congenitally blind have confirmed functional activation of the visual cortex but have not extensively explained the functional significance of these activation patterns in detail. This review systematically examines research on the role of the visual cortex in processing spatial and non-visual information, highlighting research on individuals with early and late onset blindness. Here, we concentrate on the methods utilized in studying visual cortical activation in early blind participants, including positron emissions tomography (PET), functional magnetic resonance imaging (fMRI), transcranial magnetic stimulation (TMS), and electrophysiological data, specifically event-related potentials (ERPs). This paper summarizes and discusses findings of these studies. We hypothesize how mechanisms of cortical plasticity are expressed in congenitally in comparison to adventitiously blind and short-term visually deprived sighted participants and discuss potential approaches for further investigation of these mechanisms in future research.

scholarly journals Pre-Stimulus Alpha-Band Phase Gates Afferent Visual Cortex Responses

2021 ◽  
Author(s):  
Wei Dou ◽  
Audrey Morrow ◽  
Luca Iemi ◽  
Jason Samaha
Keyword(s):  
Visual Cortex ◽  
Visual Processing ◽  
Time Window ◽  
Event Related Potentials ◽  
Alpha Phase ◽  
Alpha Activity ◽  
Alpha Band ◽  
Visual Responses ◽  
Alpha Oscillations ◽  
Related Potentials

The neurogenesis of alpha-band (8-13 Hz) activity has been characterized across many different animal experiments. However, the functional role that alpha oscillations play in perception and behavior has largely been attributed to two contrasting hypotheses, with human evidence in favor of either (or both or neither) remaining sparse. On the one hand, alpha generators have been observed in relay sectors of the visual thalamus and are postulated to phasically inhibit afferent visual input in a feedforward manner 1-4. On the other hand, evidence also suggests that the direction of influence of alpha activity propagates backwards along the visual hierarchy, reflecting a feedback influence upon the visual cortex 5-9. The primary source of human evidence regarding the role of alpha phase in visual processing has been on perceptual reports 10-16, which could be modulated either by feedforward or feedback alpha activity. Thus, although these two hypotheses are not mutually exclusive, human evidence clearly supporting either one is lacking. Here, we present human subjects with large, high-contrast visual stimuli that elicit robust C1 event-related potentials (ERP), which peak between 70-80 milliseconds post-stimulus and are thought to reflect afferent primary visual cortex (V1) input 17-20. We find that the phase of ongoing alpha oscillations modulates the global field power (GFP) of the EEG during this first volley of stimulus processing (the C1 time-window). On the standard assumption 21-23 that this early activity reflects postsynaptic potentials being relayed to visual cortex from the thalamus, our results suggest that alpha phase gates visual responses during the first feed-forward sweep of processing.

scholarly journals Effects of line orientation in visual evoked potentials. Spatial dynamics, and gender differences of neural oblique effect

2018 ◽  
Author(s):  
Elena S. Mikhailova ◽  
Natalia Yu. Gerasimenko ◽  
Anna V. Slavutskaya
Keyword(s):  
Spatial Dynamics ◽  
Oblique Effect ◽  
Event Related Potentials ◽  
Orientation Discrimination ◽  
Black And White ◽  
Cortical Areas ◽  
Visuospatial Abilities ◽  
Related Potentials ◽  
And Gender ◽  
The Brain

ABSTRACTThe aim of the study was to investigate neural mechanisms of orientation discrimination in humans by recording the 128-channel event-related potentials (ERPs) of the brain. Stimuli were black-and-white gratings having four orientations: horizontal, vertical, and oblique 45 and 135 deg. from vertical. Thirty-five healthy subjects (16 males, 19 females) participating in the experiments were asked to differentiate the orientations and push the button. The results showed that the orientation processing consists of two main stages. In the occipital, parietal and temporal areas the P100 and N150 components reflecting the early perceptual stage of processing showed amplitudes greater for oblique orientations than for cardinal ones - “inverse” oblique effect. Further, in the central-parietal and frontal areas the P300 and N400 components reflecting the later cognitive stage of processing showed the “classic” oblique effect with greater amplitudes for cardinal orientations. Females demonstrated lower ERP amplitudes and less pronounced differences between responses elicited by cardinal and oblique orientations. The results suggest that in humans the orientation discrimination occurs in a distributed neural network involving the early sensory as well as higher anterior cortical areas. The classic behavioral oblique effect might be controlled by later processing in the anterior cortical areas. The insufficient neural orientation selectivity observed in females may be considered as the biological basis of their poorer visuospatial abilities.

Stereotactic electroencephalography in humans reveals multisensory signal in early visual and auditory cortices

2019 ◽  
Author(s):  
Stefania Ferraro ◽  
Markus J. Van Ackeren ◽  
Roberto Mai ◽  
Laura Tassi ◽  
Francesco Cardinale ◽  
...  
Keyword(s):  
Visual Cortex ◽  
Auditory Cortex ◽  
Auditory Processing ◽  
Multisensory Processing ◽  
Low Frequency ◽  
Event Related Potentials ◽  
Stimulus Onset ◽  
Oscillatory Activity ◽  
Visual Responses ◽  
Related Potentials

AbstractUnequivocally demonstrating the presence of multisensory signals at the earliest stages of cortical processing remains challenging in humans. In our study, we relied on the unique spatio-temporal resolution provided by intracranial stereotactic electroencephalographic (SEEG) recordings in patients with drug-resistant epilepsy to characterize the signal extracted from early visual (calcarine and pericalcarine) and auditory (Heschl’s gyrus and planum temporale) regions during a simple audio-visual oddball task. We provide evidences that both cross-modal responses (visual responses in auditory cortex or the reverse) and multisensory processing (alteration of the unimodal responses during bimodal stimulation) can be observed in intracranial event-related potentials (iERPs) and in power modulations of oscillatory activity at different temporal scales within the first 150 ms after stimulus onset. The temporal profiles of the iERPs are compatible with the hypothesis that MSI occurs by means of direct pathways linking early visual and auditory regions. Our data indicate, moreover, that MSI mainly relies on modulations of the low-frequency bands (foremost the theta band in the auditory cortex and the alpha band in the visual cortex), suggesting the involvement of feedback pathways between the two sensory regions. Remarkably, we also observed high-gamma power modulations by sounds in the early visual cortex, thus suggesting the presence of neuronal populations involved in auditory processing in the calcarine and pericalcarine region in humans.

Auditory click stimuli evoke event-related potentials in the visual cortex

Neuroreport ◽  
2013 ◽  
Vol 24 (15) ◽  
pp. 837-840 ◽  
Author(s):  
Susan Pockett ◽  
Suzanne C. Purdy ◽  
Barry J. Brennan ◽  
Mark D. Holmes
Keyword(s):  
Visual Cortex ◽  
Event Related Potentials ◽  
Related Potentials

scholarly journals Perceptual Learning of Simple Stimuli Modifies Stimulus Representations in Posterior Inferior Temporal Cortex

2014 ◽  
Vol 26 (10) ◽  
pp. 2187-2200 ◽  
Author(s):  
Hamed Zivari Adab ◽  
Ivo D. Popivanov ◽  
Wim Vanduffel ◽  
Rufin Vogels
Keyword(s):  
Visual Cortex ◽  
Perceptual Learning ◽  
Single Unit ◽  
Brain Plasticity ◽  
Temporal Cortex ◽  
Adult Brain ◽  
Orientation Discrimination ◽  
Area V4 ◽  
Early Visual Cortex ◽  
Visual Cortical

Practicing simple visual detection and discrimination tasks improves performance, a signature of adult brain plasticity. The neural mechanisms that underlie these changes in performance are still unclear. Previously, we reported that practice in discriminating the orientation of noisy gratings (coarse orientation discrimination) increased the ability of single neurons in the early visual area V4 to discriminate the trained stimuli. Here, we ask whether practice in this task also changes the stimulus tuning properties of later visual cortical areas, despite the use of simple grating stimuli. To identify candidate areas, we used fMRI to map activations to noisy gratings in trained rhesus monkeys, revealing a region in the posterior inferior temporal (PIT) cortex. Subsequent single unit recordings in PIT showed that the degree of orientation selectivity was similar to that of area V4 and that the PIT neurons discriminated the trained orientations better than the untrained orientations. Unlike in previous single unit studies of perceptual learning in early visual cortex, more PIT neurons preferred trained compared with untrained orientations. The effects of training on the responses to the grating stimuli were also present when the animals were performing a difficult orthogonal task in which the grating stimuli were task-irrelevant, suggesting that the training effect does not need attention to be expressed. The PIT neurons could support orientation discrimination at low signal-to-noise levels. These findings suggest that extensive practice in discriminating simple grating stimuli not only affects early visual cortex but also changes the stimulus tuning of a late visual cortical area.

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