Form-From-Motion: MEG Evidence for Time Course and Processing Sequence

2003 ◽  
Vol 15 (2) ◽  
pp. 157-172 ◽  
Author(s):  
M. A. Schoenfeld ◽  
M. Woldorff ◽  
E. Düzel ◽  
H. Scheich ◽  
H.-J. Heinze ◽  
...  
Keyword(s):  
Spatial Attention ◽  
Time Course ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Inferior Temporal Cortex ◽  
Cortical Region ◽  
Motion Cues ◽  
Form Analysis ◽  
Msec Delay ◽  
Visual Cortical

The neural mechanisms and role of attention in the processing of visual form defined by luminance or motion cues were studied using magnetoencephalography. Subjects viewed bilateral stimuli composed of moving random dots and were instructed to covertly attend to either left or right hemifield stimuli in order to detect designated target stimuli that required a response. To generate form-from-motion (FFMo) stimuli, a subset of the dots could begin to move coherently to create the appearance of a simple form (e.g., square). In other blocks, to generate form-from-luminance (FFLu) stimuli that served as a control, a gray stimulus was presented superimposed on the randomly moving dots. Neuromagnetic responses were observed to both the FFLu and FFMo stimuli and localized to multiple visual cortical stages of analysis. Early activity in low-level visual cortical areas (striate/early extrastriate) did not differ for FFLu versus FFMo stimuli, nor as a function of spatial attention. Longer latency responses elicited by the FFLu stimuli were localized to the ventral-lateral occipital cortex (LO) and the inferior temporal cortex (IT). The FFMo stimuli also generated activity in the LO and IT, but only after first eliciting activity in the lateral occipital cortical region corresponding to MT/V5, resulting in a 50–60 msec delay in activity. All of these late responses (MT/V5, LO, and IT) were significantly modulated by spatial attention, being greatly attenuated for ignored FFLu and FFMo stimuli. These findings argue that processing of form in IT that is defined by motion requires a serial processing of information, first in the motion analysis pathway from V1 to MT/V5 and thereafter via the form analysis stream in the ventral visual pathway to IT.

scholarly journals Unsupervised changes in core object recognition behavior are predicted by neural plasticity in inferior temporal cortex

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Xiaoxuan Jia ◽  
Ha Hong ◽  
Jim DiCarlo
Keyword(s):  
Object Recognition ◽  
Neural Plasticity ◽  
Time Course ◽  
Human Performance ◽  
Temporal Cortex ◽  
Neural Representation ◽  
Temporal Contiguity ◽  
Inferior Temporal Cortex ◽  
Object Identity ◽  
Visual Stream

Temporal continuity of object identity is a feature of natural visual input, and is potentially exploited -- in an unsupervised manner -- by the ventral visual stream to build the neural representation in inferior temporal (IT) cortex. Here we investigated whether plasticity of individual IT neurons underlies human core-object-recognition behavioral changes induced with unsupervised visual experience. We built a single-neuron plasticity model combined with a previously established IT population-to-recognition-behavior linking model to predict human learning effects. We found that our model, after constrained by neurophysiological data, largely predicted the mean direction, magnitude and time course of human performance changes. We also found a previously unreported dependency of the observed human performance change on the initial task difficulty. This result adds support to the hypothesis that tolerant core object recognition in human and non-human primates is instructed -- at least in part -- by naturally occurring unsupervised temporal contiguity experience.

Enhancement of inferior temporal neurons during visual discrimination

1987 ◽  
Vol 58 (6) ◽  
pp. 1292-1306 ◽  
Author(s):  
B. J. Richmond ◽  
T. Sato
Keyword(s):  
Spatial Attention ◽  
Trial Type ◽  
Discrimination Task ◽  
Temporal Cortex ◽  
Pattern Discrimination ◽  
Response Strength ◽  
The Other ◽  
Inferior Temporal Cortex ◽  
Attention Task ◽  
Type Pattern

1. Previous results have shown that spatially directed attention enhances the stimulus-elicited responses of neurons in some areas of the brain. In the inferior temporal (IT) cortex, however, directing attention toward a stimulus mildly inhibits the responses of the neurons. Inferior temporal cortex is involved in pattern discrimination, but not spatial localization. If enhancement signifies that a neuron is participating in the function for which that part of cortex is responsible, then pattern discrimination, not spatial attention, should enhance responses of IT neurons. The influence of pattern discrimination behavior on the responses of IT neurons was therefore compared with previously reported suppressive influences of both spatial attention and the fixation point. 2. Single IT neurons were recorded from two monkeys while they performed each of five tasks. One task required the monkey to make a pattern discrimination between a bar and a square of light. In the other four tasks the same bar of light appeared, but the focus of spatial attention could differ, and the fixation point could be present or absent. Either attention to (without discrimination of) the bar stimulus or the presence of the fixation point attenuated responses slightly. These two suppressive influences produced a greater attenuation when both were present. 3. The visual conditions and motor requirements when the bar stimulus appeared in the discrimination task were identical to those of the trials in the stimulus attention task. However, one-half of the responsive neurons showed significantly stronger responses to the bar stimulus when it appeared in the discrimination task than when it appeared in the stimulus attention task. For most of these neurons, discrimination just overcame the combined effect of the two suppressive influences. For six other neurons, the response strength was significantly greater during the discrimination task than during any other task. 4. The monkeys achieved an overall correct performance rate of 90% in both the discrimination and stimulus attention tasks. To achieve this performance in the discrimination task they adopted a strategy in which they performed one trial type, bar stimulus attention trials, perfectly (100%) and the other trial type, pattern trials, relatively poorly (84% correct).(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Theta-burst TMS of lateral occipital cortex reduces BOLD responses across category-selective areas in ventral temporal cortex

2020 ◽  
Author(s):  
Iris I A Groen ◽  
Edward H Silson ◽  
David Pitcher ◽  
Chris I Baker
Keyword(s):  
Temporal Cortex ◽  
Occipital Cortex ◽  
Brain Regions ◽  
Stimulus Category ◽  
Cortical Region ◽  
Face Area ◽  
Before And After ◽  
Ventral Temporal Cortex ◽  
Theta Burst ◽  
Lateral Occipital Cortex

AbstractHuman visual cortex contains three scene-selective regions in the lateral, medial and ventral cortex, termed the occipital place area (OPA), medial place area (MPA) and parahippocampal place area (PPA). Using functional magnetic resonance imaging (fMRI), all three regions respond more strongly when viewing visual scenes compared with isolated objects or faces. To determine how these regions are functionally and causally connected, we applied transcranial magnetic stimulation to OPA and measured fMRI responses before and after stimulation, using a theta-burst paradigm (TBS). To test for stimulus category-selectivity, we presented a range of visual categories (scenes, buildings, objects, faces). To test for specificity of any effects to TBS of OPA we employed two control conditions: Sham, with no TBS stimulation, and an active TBS-control with TBS to a proximal face-selective cortical region (occipital face area, or OFA). We predicted that TBS to OPA (but not OFA) would lead to decreased responses to scenes and buildings (but not other categories) in other scene-selective cortical regions. Across both ROI and whole-volume analyses, we observed decreased responses to scenes in PPA as a result of TBS. However, these effects were neither category specific, with decreased responses to all stimulus categories, nor limited to scene-selective regions, with decreases also observed in face-selective fusiform face area (FFA). Furthermore, similar effects were observed with TBS to OFA, thus effects were not specific to the stimulation site in the lateral occipital cortex. Whilst these data are suggestive of a causal, but non-specific relationship between lateral occipital and ventral temporal cortex, we discuss several factors that could have underpinned this result, such as the differences between TBS and online TMS, the role of anatomical distance between stimulated regions and how TMS effects are operationalised. Furthermore, our findings highlight the importance of active control conditions in brain stimulation experiments to accurately assess functional and causal connectivity between specific brain regions.

Frontoparietal Control of Spatial Attention and Motor Intention in Human EEG

2005 ◽  
Vol 94 (1) ◽  
pp. 764-774 ◽  
Author(s):  
Peter Praamstra ◽  
Luc Boutsen ◽  
Glyn W. Humphreys
Keyword(s):  
Spatial Attention ◽  
Time Course ◽  
Response Selection ◽  
Occipital Cortex ◽  
Directional Information ◽  
Attention Network ◽  
Human Eeg ◽  
Frontoparietal Network ◽  
Motor Intention ◽  
And Function

Relations between spatial attention and motor intention were investigated by means of an EEG potential elicited by shifting attention to a location in space as well as by the selection of a hand for responding. High-density recordings traced this potential to a common frontoparietal network activated by attentional orienting and by response selection. Within this network, parietal and frontal cortex were activated sequentially, followed by an anterior-to-posterior migration of activity culminating in the lateral occipital cortex. Based on temporal and polarity information provided by EEG, we hypothesize that the frontoparietal activation, evoked by directional information, updates a task-defined preparatory state by deselecting or inhibiting the behavioral option competing with the cued response side or the cued direction of attention. These results from human EEG demonstrate a direct EEG manifestation of the frontoparietal attention network previously identified in functional imaging. EEG reveals the time-course of activation within this network and elucidates the generation and function of associated directing-attention EEG potentials. The results emphasize transient activation and a decision-related function of the frontoparietal attention network, contrasting with the sustained preparatory activation that is commonly inferred from neuroimaging.

Neural Substrates of Perceptual Enhancement by Cross-Modal Spatial Attention

2003 ◽  
Vol 15 (1) ◽  
pp. 10-19 ◽  
Author(s):  
John J. McDonald ◽  
Wolfgang A. Teder-Sälejärvi ◽  
Francesco Di Russo ◽  
Steven A. Hillyard
Keyword(s):  
Spatial Attention ◽  
Brain Activity ◽  
Visual Stimuli ◽  
Temporal Cortex ◽  
Electrode Array ◽  
Event Related Potentials ◽  
Occipital Cortex ◽  
Neural Substrates ◽  
Superior Temporal Cortex ◽  
Related Potentials

Orienting attention involuntarily to the location of a sudden sound improves perception of subsequent visual stimuli that appear nearby. The neural substrates of this cross-modal attention effect were investigated by recording event-related potentials to the visual stimuli using a dense electrode array and localizing their brain sources through inverse dipole modeling. A spatially nonpredictive auditory precue modulated visual-evoked neural activity first in the superior temporal cortex at 120–140 msec and then in the ventral occipital cortex of the fusiform gyrus 15–25 msec later. This spatio-temporal sequence of brain activity suggests that enhanced visual perception produced by the cross-modal orienting of spatial attention results from neural feedback from the multimodal superior temporal cortex to the visual cortex of the ventral processing stream.

scholarly journals Visual information routes in the posterior dorsal and ventral face network studied with intracranial neurophysiology, and white matter tract endpoints

2020 ◽  
Author(s):  
M Babo-Rebelo ◽  
A Puce ◽  
D Bullock ◽  
L Hugueville ◽  
F Pestilli ◽  
...  
Keyword(s):  
White Matter ◽  
Face Processing ◽  
Visual Information ◽  
Temporal Cortex ◽  
Field Potential ◽  
Occipital Cortex ◽  
Inferior Temporal Cortex ◽  
Direct Gaze ◽  
Superior Temporal Cortex ◽  
White Matter Tractography

ABSTRACTOccipito-temporal regions within the face network process perceptual and socio-emotional information, but the dynamics and interactions between different nodes within this network remain unknown. Here, we analyzed intracerebral EEG from 11 epileptic patients viewing a stimulus sequence beginning with a neutral face with direct gaze. The gaze could avert or remain direct, while the emotion changed to fearful or happy. N200 field potential peak latencies indicated that face processing begins in inferior occipital cortex and proceeds anteroventrally to fusiform and inferior temporal cortices, in parallel. The superior temporal sulcus responded preferentially to gaze changes with augmented field potential amplitudes for averted versus direct gaze, and large effect sizes relative to other regions of the network. An overlap analysis of posterior white matter tractography endpoints (from 1066 healthy brains) relative to active intracerebral electrodes from the 11 patients showed likely involvement of both dorsal and ventral posterior white matter pathways. The inferior occipital and temporal sulci likely broadcast their information - the former dorsally to intraparietal sulcus, and the latter between fusiform and superior temporal cortex. Overall, our data call for inclusion of inferior temporal cortex in face processing models, and anchor the superior temporal cortex in dynamic gaze processing.

Modality Dependent Cross-Modal Functional Reorganization Following Congenital Visual Deprivation within Occipital Areas: A Meta-Analysis of Tactile and Auditory Studies

2014 ◽  
Vol 27 (3-4) ◽  
pp. 247-262 ◽  
Author(s):  
Emiliano Ricciardi ◽  
Leonardo Tozzi ◽  
Andrea Leo ◽  
Pietro Pietrini
Keyword(s):  
Visual Information ◽  
Meta Analysis ◽  
Sensory Modality ◽  
Temporal Cortex ◽  
Sensory Information ◽  
Occipital Cortex ◽  
Inferior Temporal Cortex ◽  
Functional Studies ◽  
Superior Parietal Cortex ◽  
Blind Individuals

Cross-modal responses in occipital areas appear to be essential for sensory processing in visually deprived subjects. However, it is yet unclear whether this functional recruitment might be dependent on the sensory channel conveying the information. In order to characterize brain areas showing task-independent, but sensory specific, cross-modal responses in blind individuals, we pooled together distinct brain functional studies in a single based meta-analysis according only to the modality conveying experimental stimuli (auditory or tactile). Our approach revealed a specific functional cortical segregation according to the sensory modality conveying the non-visual information, irrespectively from the cognitive features of the tasks. In particular, dorsal and posterior subregions of occipital and superior parietal cortex showed a higher cross-modal recruitment across tactile tasks in blind as compared to sighted individuals. On the other hand, auditory stimuli activated more medial and ventral clusters within early visual areas, the lingual and inferior temporal cortex. These findings suggest a modality-specific functional modification of cross-modal responses within different portions of the occipital cortex of blind individuals. Cross-modal recruitment can thus be specifically influenced by the intrinsic features of sensory information.

Learning selective top-down control enhances performance in a visual categorization task

2012 ◽  
Vol 108 (11) ◽  
pp. 3124-3137 ◽  
Author(s):  
Mario Pannunzi ◽  
Guido Gigante ◽  
Maurizio Mattia ◽  
Gustavo Deco ◽  
Stefano Fusi ◽  
...  
Keyword(s):  
Time Course ◽  
Signal To Noise Ratio ◽  
Temporal Cortex ◽  
Inferior Temporal Cortex ◽  
Feedback Signal ◽  
Top Down ◽  
Categorization Task ◽  
Tuning Curves ◽  
Visual Categorization ◽  
Neural Activities

We model the putative neuronal and synaptic mechanisms involved in learning a visual categorization task, taking inspiration from single-cell recordings in inferior temporal cortex (ITC). Our working hypothesis is that learning the categorization task involves both bottom-up, ITC to prefrontal cortex (PFC), and top-down (PFC to ITC) synaptic plasticity and that the latter enhances the selectivity of the ITC neurons encoding the task-relevant features of the stimuli, thereby improving the signal-to-noise ratio. We test this hypothesis by modeling both areas and their connections with spiking neurons and plastic synapses, ITC acting as a feature-selective layer and PFC as a category coding layer. This minimal model gives interesting clues as to properties and function of the selective feedback signal from PFC to ITC that help solving a categorization task. In particular, we show that, when the stimuli are very noisy because of a large number of nonrelevant features, the feedback structure helps getting better categorization performance and decreasing the reaction time. It also affects the speed and stability of the learning process and sharpens tuning curves of ITC neurons. Furthermore, the model predicts a modulation of neural activities during error trials, by which the differential selectivity of ITC neurons to task-relevant and task-irrelevant features diminishes or is even reversed, and modulations in the time course of neural activities that appear when, after learning, corrupted versions of the stimuli are input to the network.

scholarly journals Unsupervised changes in core object recognition behavior are predicted by neural plasticity in inferior temporal cortex

2020 ◽  
Author(s):  
Xiaoxuan Jia ◽  
Ha Hong ◽  
James J. DiCarlo
Keyword(s):  
Object Recognition ◽  
Neural Plasticity ◽  
Time Course ◽  
Human Performance ◽  
Temporal Cortex ◽  
Neural Representation ◽  
Temporal Contiguity ◽  
Inferior Temporal Cortex ◽  
Object Identity ◽  
Visual Stream

AbstractTemporal continuity of object identity is a feature of natural visual input, and is potentially exploited -- in an unsupervised manner -- by the ventral visual stream to build the neural representation in inferior temporal (IT) cortex and IT-dependent core object recognition behavior. Here we investigated whether plasticity of individual IT neurons underlies human behavioral changes induced with unsupervised visual experience by building a single-neuron plasticity model combined with a previously established IT population-to-recognition-behavior linking model to predict human learning effects. We found that our model quite accurately predicted the mean direction, magnitude and time course of human performance changes. We also found a previously unreported dependency of the observed human performance change on the initial task difficulty. This result adds support to the hypothesis that tolerant core object recognition in human and non-human primates is instructed -- at least in part -- by naturally occurring unsupervised temporal contiguity experience.

scholarly journals Neural Substrates Associated With Fatigue Symptom In Fibromyalgia

2022 ◽  
Author(s):  
Hung-Yu Liu ◽  
Pei-Lin Lee ◽  
Kun-Hsien Chou ◽  
Yen-Feng Wang ◽  
Shih-Pin Chen ◽  
...  
Keyword(s):  
Brain Mri ◽  
Temporal Cortex ◽  
Occipital Cortex ◽  
Neural Substrates ◽  
Inferior Temporal Cortex ◽  
Morphometry Analysis ◽  
Fatigue Severity ◽  
Subcortical Regions ◽  
The Right ◽  
Neural Signatures

Abstract Many patients with fibromyalgia (FM) experience fatigue, but the associated biological mechanisms have not been delineated. We aimed to investigate the neural signatures associated with fatigue severity in patients with FM using MRI. We consecutively recruited 138 patients with FM and collected their clinical profiles and brain-MRI data. We categorized the patients into 3 groups based on their fatigue severity. Using voxel-based morphometry analysis and trend analysis, we first identified neural structures showing volumetric changes associated with fatigue severity, and further explored their seed-to-voxel structural covariance networks (SCNs). Results showed decreased bilateral thalamic volumes were associated with higher severity of fatigue. There was a more widespread distribution of the thalamic SCNs to the frontal, parietal, subcortical, and limbic regions in patients with higher fatigue severity. In addition, increased right inferior temporal cortex volumes were associated with higher severity of fatigue. The right inferior temporal seed showed more SCNs distributions over the temporal cortex and a higher strength of SCNs to the bilateral occipital cortex in patients with higher fatigue severity. The thalamus and the right inferior temporal cortex as well as their altered interactions with cortical and subcortical regions comprise the neural signatures of fatigue in FM.

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