Push-Pull Mechanism of Selective Attention in Human Extrastriate Cortex

Selective attention operates in visual cortex by facilitating processing of selected stimuli and by filtering out unwanted information from nearby distracters over circumscribed regions of visual space. The neural representation of unattended stimuli outside this focus of attention is less well understood. We studied the neural fate of unattended stimuli using functional magnetic resonance imaging by dissociating the activity evoked by attended (target) stimuli presented to the periphery of a visual hemifield and unattended (distracter) stimuli presented simultaneously to a corresponding location of the contralateral hemifield. Subjects covertly directed attention to a series of target stimuli and performed either a low or a high attentional-load search task on a stream of otherwise identical stimuli. With this task, target-search-related activity increased with increasing attentional load, whereas distracter-related activity decreased with increasing load in areas V4 and TEO but not in early areas V1 and V2. This finding presents evidence for a load-dependent push-pull mechanism of selective attention that operates over large portions of the visual field at intermediate processing stages. This mechanism appeared to be controlled by a distributed frontoparietal network of brain areas that reflected processes related to target selection during spatially directed attention.

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Structural alterations in the macaque frontoparietal white matter network after recovery from prefrontal cortex lesions

10.1101/2020.05.02.064840 ◽

2020 ◽

Author(s):

Ramina Adam ◽

David J. Schaeffer ◽

Kevin Johnston ◽

Ravi S. Menon ◽

Stefan Everling

Keyword(s):

Prefrontal Cortex ◽

White Matter ◽

Structural Damage ◽

Posterior Parietal Cortex ◽

Target Selection ◽

Saccade Target ◽

Functional Changes ◽

Frontoparietal Network ◽

Fiber Tracts ◽

Visual Hemifield

AbstractUnilateral damage to the frontoparietal network typically impairs saccade target selection within the contralesional visual hemifield. Severity of deficits and the degree of recovery have been associated with widespread network dysfunction, yet it is not clear how these behavioural and functional changes relate with the underlying structural white matter pathways. Here, we investigated whether recovery after unilateral prefrontal cortex (PFC) lesions was associated with structural white matter remodeling in the distributed frontoparietal network. Diffusion-weighted MRI was acquired in four macaque monkeys before the lesions and at 2-4 months post-lesion, after recovery of deficits in saccade selection of contralesional targets. Probabilistic tractography was used to reconstruct inter- and intra-hemispheric frontoparietal fiber tracts: bilateral superior longitudinal fasciculus (SLF) and transcallosal fibers connecting bilateral PFC or bilateral posterior parietal cortex (PPC). After behavioural recovery, tract-specific fractional anisotropy in contralesional SLF and transcallosal PPC increased after small lesions and decreased after larger lesions compared to pre-lesion. These findings indicate that remote fiber tracts may provide optimal compensation after small PFC lesions. However, larger lesions may have induced widespread structural damage and hindered compensatory remodeling in the structural frontoparietal network.

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Enhanced representation of space by prefrontal neuronal ensembles and its dependence on cognitive states

10.1101/065581 ◽

2016 ◽

Author(s):

Mohammad-Reza A. Dehaqani ◽

Abdol-Hossein Vahabie ◽

Mohammadbagher Parsa ◽

Behard Noudoost ◽

Alireza Soltani

Keyword(s):

Cognitive Flexibility ◽

Target Selection ◽

Visual Space ◽

Neural Representation ◽

Noise Correlation ◽

Neuronal Ensembles ◽

Cognitive States ◽

Visual Encoding ◽

Representation Of Space ◽

Spatial Locations

AbstractAlthough individual neurons can be highly selective to particular stimuli and certain upcoming actions, they can provide a complex representation of stimuli and actions at the level of population. The ability to dynamically allocate neural resources is crucial for cognitive flexibility. However, it is unclear whether cognitive flexibility emerges from changes in activity at the level of individual neurons, population, or both. By applying a combination of decoding and encoding methods to simultaneously recorded neural data, we show that while maintaining their stimulus selectivity, neurons in prefrontal cortex alter their correlated activity during various cognitive states, resulting in an enhanced representation of visual space. During a task with various cognitive states, individual prefrontal neurons maintained their limited spatial sensitivity between visual encoding and saccadic target selection whereas the population selectively improved its encoding of spatial locations far from the neurons' preferred locations. This 'encoding expansion' relied on high-dimensional neural representations and was accompanied by selective reductions in noise correlation for non-preferred locations. Our results demonstrate that through recruitment of less-informative neurons and reductions of noise correlation in their activity, the representation of space by neuronal ensembles can be dynamically enhanced, and suggest that cognitive flexibility is mainly achieved by changes in neural representation at the level of population of prefrontal neurons rather than individual neurons.

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Representation of three-dimensional visual space in the cerebral cortex

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y88-077 ◽

1988 ◽

Vol 66 (4) ◽

pp. 478-487 ◽

Cited By ~ 4

Author(s):

John H. R. Maunsell

Keyword(s):

Cerebral Cortex ◽

Visual Field ◽

Dimensional Space ◽

Three Dimensional ◽

Visual Space ◽

Neural Representation ◽

Complex Stimulus ◽

Visual Hemifield ◽

Extrastriate Areas ◽

Three Dimensional Space

This article reviews two issues relevant to the topic of how three-dimensional space is represented in the cerebral cortex. The first is the question of how individual neurons encode information that might contribute to stereoscopic estimation of visual depth. Particular attention is given to the current understanding of the neural representation of motion through three-dimensional space and to the complexities that arise in interpreting neuronal responses to this complex stimulus parameter. The second issue considered is the disorderliness that exists in the retinotopic mapping of the visual field in some cortical visual areas. Several extrastriate areas have been found to contain maps of the contralateral visual hemifield that are disorderly in the sense that the representation of various parts of the visual field are often misplaced or grossly over-or under-represented. It is suggested that this disorderliness may in some cases represent adaptations to facilitate certain types of visual functions.

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Spatial suppression due to statistical regularities is driven by distractor suppression not by target activation

10.31234/osf.io/zbcjv ◽

2018 ◽

Author(s):

Michel Failing ◽

Benchi Wang ◽

Jan Theeuwes

Keyword(s):

High Probability ◽

Target Location ◽

Target Selection ◽

Visual Space ◽

Alternative Interpretation ◽

Distractor Location ◽

Target Presentation ◽

Statistical Regularities ◽

Low Probability ◽

Presentation Experiment

Where and what we attend to is not only determined by what we are currently looking for but also by what we have encountered in the past. Recent studies suggest that biasing the probability by which distractors appear at locations in visual space may lead to attentional suppression of high probability distractor locations which effectively reduces capture by a distractor but also impairs target selection at this location. However, in many of these studies introducing a high probability distractor location was tantamount to increasing the probability of the target appearing in any of the other locations (i.e. the low probability distractor locations). Here, we investigate an alternative interpretation of previous findings according to which attentional selection at high probability distractor locations is not suppressed. Instead, selection at low probability distractor locations is facilitated. In two visual search tasks, we found no evidence for this hypothesis: neither when there was only a bias in target presentation but no bias in distractor presentation (Experiment 1), nor when there was only a bias in distractor presentation but no bias in target presentation (Experiment 2). We conclude that recurrent presentation of a distractor in a specific location leads to attentional suppression of that location through a mechanism that is unaffected by any regularities regarding the target location.

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Color signals through dorsal and ventral visual pathways

Visual Neuroscience ◽

10.1017/s0952523813000382 ◽

2013 ◽

Vol 31 (2) ◽

pp. 197-209 ◽

Cited By ~ 36

Author(s):

BEVIL R. CONWAY

Keyword(s):

Visual Processing ◽

Color Space ◽

Temporal Cortex ◽

Color Perception ◽

Original Data ◽

Brain Regions ◽

Neural Representation ◽

Inferior Temporal Cortex ◽

Extrastriate Cortex ◽

Chromatic Contrast

AbstractExplanations for color phenomena are often sought in the retina, lateral geniculate nucleus, and V1, yet it is becoming increasingly clear that a complete account will take us further along the visual-processing pathway. Working out which areas are involved is not trivial. Responses to S-cone activation are often assumed to indicate that an area or neuron is involved in color perception. However, work tracing S-cone signals into extrastriate cortex has challenged this assumption: S-cone responses have been found in brain regions, such as the middle temporal (MT) motion area, not thought to play a major role in color perception. Here, we review the processing of S-cone signals across cortex and present original data on S-cone responses measured with fMRI in alert macaque, focusing on one area in which S-cone signals seem likely to contribute to color (V4/posterior inferior temporal cortex) and on one area in which S signals are unlikely to play a role in color (MT). We advance a hypothesis that the S-cone signals in color-computing areas are required to achieve a balanced neural representation of perceptual color space, whereas those in noncolor-areas provide a cue to illumination (not luminance) and confer sensitivity to the chromatic contrast generated by natural daylight (shadows, illuminated by ambient sky, surrounded by direct sunlight). This sensitivity would facilitate the extraction of shape-from-shadow signals to benefit global scene analysis and motion perception.

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Brainstem Frequency-Following Responses and Cortical Event-Related Potentials during Attention

Perceptual and Motor Skills ◽

10.2466/pms.1993.76.3c.1231 ◽

1993 ◽

Vol 76 (3_suppl) ◽

pp. 1231-1241 ◽

Cited By ~ 14

Author(s):

Gary C. Galbraith ◽

John M. Kane

Keyword(s):

Selective Attention ◽

Low Frequency ◽

Event Related Potentials ◽

Specific Task ◽

Directed Attention ◽

Auditory Evoked Response ◽

Cortical Responses ◽

Task Requirements ◽

Related Potentials ◽

Brainstem Auditory Evoked Response

Human brainstem frequency-following responses (FFRs) and cortical event-related potentials (ERPs) were evoked by a low-frequency (230 Hz) tone during directed attention. ERPs showed significant amplitude differences consistent with expected attention effects, viz., largest to attended stimuli and smallest to ignored stimuli. The ERP data thereby confirm that attention effectively modulated cortical responses. The FFR, however, did not differ between conditions. The present results agree with one earlier FFR study and a majority of studies using click stimuli to elicit the brainstem auditory evoked response (BAER). However, several BAER studies and two recent FFR studies have shown that attention can influence human brainstem responses. The present results are therefore interpreted in the context of specific task requirements that optimize early selective attention effects.

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Mechanism of anomalous retinal correspondence: Maintenance of binocularity with alteration of receptive-field position in the lateral suprasylvian (LS) visual area of strabismic cats

Visual Neuroscience ◽

10.1017/s0952523800004077 ◽

1991 ◽

Vol 7 (3) ◽

pp. 259-281 ◽

Cited By ~ 16

Author(s):

Simon Grant ◽

Nancy E. J. Berman

Keyword(s):

Receptive Field ◽

Ocular Dominance ◽

Visual Space ◽

Extrastriate Cortex ◽

Area 17 ◽

Visual Inputs ◽

Corneal Reflex ◽

Adult Cats ◽

Retinal Correspondence ◽

Field Position

AbstractWe have examined the effects of rearing kittens with a unilateral convergent strabismus, induced surgically at 3 weeks of age, on the binocularity (ocular dominance) and receptive-field position of neurons in the motion-sensitive lateral suprasylvian (LS) area of cat extrastriate cortex. Data were compared to those obtained from area 17 in the same animals, and from the two areas of cortex in normal adult cats. Interocular alignment of the operated cats was assessed in alert adults using corneal reflex photography and during recording from the positions of retinal landmarks under paralysis. The strabismus magnitude in each operated cat was calculated by comparison with equivalent data from the normal animals.Strabismus always caused a major loss of binocularity in area 17. The remaining binocular neurons had receptive-field (RF) pairs arising from positions of normal correspondence in the two retinae and would thus have been responsive to different regions of visual space through the misaligned eyes in the alert animal. In area LS, the effects were dependent on the strabismus magnitude. In the group of four cats with pronounced strabismus (18–30 deg crossed), a loss of binocularity occurred in area LS equivalent in severity to that in area 17. The majority of the remaining binocular LS neurons possessed RF pairs in normal retinal correspondence and would thus, in the alert animal, have received spatially disparate visual input through the two eyes. This also occurred in three other cats with more moderate strabismus (11–15 deg crossed), although only a small breakdown in the binocularity of area LS was apparent. The group of cats with mild strabismus (≤10 deg crossed) had normal proportions of binocular neurons in area LS. In three of these cats, the maintenance of binocularity was accompanied by shifts in RF position, with visual inputs arising from anomalous retinal locations. These shifts compensated, in part, for the strabismus angle present in each cat, so that most of the binocular LS neurons would have received inputs from regions of visual correspondence through the misaligned eyes when the animal was alert.Similar mechanisms could afford a basis for the binocular visual compensations that occur in humans with small-angle strabismus of early onset. If so, anomalous retinal correspondence in such individuals would have as a locus areas of extrastriate cortex with a role in motion perception, and would involve alterations to the neural substrate underlying normal binocular vision.

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