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

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.

Push-Pull Mechanism of Selective Attention in Human Extrastriate Cortex

2004 ◽  
Vol 92 (1) ◽  
pp. 622-629 ◽  
Author(s):  
Mark A. Pinsk ◽  
Glen M. Doniger ◽  
Sabine Kastner
Keyword(s):  
Selective Attention ◽  
Target Selection ◽  
Visual Space ◽  
Neural Representation ◽  
Extrastriate Cortex ◽  
Related Activity ◽  
Directed Attention ◽  
Frontoparietal Network ◽  
Visual Hemifield ◽  
Attentional Load

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.

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

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.

Neural Representation of Space Using Sinusoidal Arrays

1993 ◽  
Vol 5 (6) ◽  
pp. 869-884 ◽  
Author(s):  
David S. Touretzky ◽  
A. David Redish ◽  
Hank S. Wan
Keyword(s):  
Computer Simulations ◽  
Parietal Cortex ◽  
Spatial Information ◽  
Sine Wave ◽  
Spiking Neurons ◽  
Neural Representation ◽  
Temporal Dimension ◽  
Response Properties ◽  
Representation Of Space

O'Keefe (1991) has proposed that spatial information in rats might be represented as phasors: phase and amplitude of a sine wave encoding angle and distance to a landmark. We describe computer simulations showing that operations on phasors can be efficiently realized by arrays of spiking neurons that recode the temporal dimension of the sine wave spatially. Some cells in motor and parietal cortex exhibit response properties compatible with this proposal.

Motion, space, and mental imagery

2002 ◽  
Vol 25 (2) ◽  
pp. 203-204 ◽  
Author(s):  
Romi Nijhawan ◽  
Beena Khurana
Keyword(s):  
Mental Imagery ◽  
Spatial Representation ◽  
Visual Motion ◽  
Visual Space ◽  
Mental Images ◽  
Representation Of Space ◽  
Imagery Debate

In the imagery debate, a key question concerns the inherent spatial nature of mental images. What do we mean by spatial representation? We explore a new idea that suggests that motion is instrumental in the coding of visual space. How is the imagery debate informed by the representation of space being determined by visual motion?

scholarly journals Visual encoding and fixation target selection in free viewing: presaccadic brain potentials

2013 ◽  
Vol 7 ◽  
Author(s):  
Andrey R. Nikolaev ◽  
Peter Jurica ◽  
Chie Nakatani ◽  
Gijs Plomp ◽  
Cees van Leeuwen
Keyword(s):  
Target Selection ◽  
Fixation Target ◽  
Brain Potentials ◽  
Free Viewing ◽  
Visual Encoding

scholarly journals Emotional representations of space vary as a function of peoples’ mental health and interoceptive awareness

2021 ◽  
Author(s):  
Alejandro Galvez-Pol ◽  
Marcos Nadal ◽  
James Kilner
Keyword(s):  
Mental Health ◽  
Interoceptive Awareness ◽  
Natural Environments ◽  
Emotional Representation ◽  
Representation Of Space ◽  
Bodily Sensations ◽  
Psychophysiological Correlates ◽  
Emotional Representations ◽  
Spatial Locations ◽  
Representations Of Space

As people interact in extensive environments, their space becomes intertwined with emotions. Yet, beyond the study of spatial appraisal and navigation1–3, the emotional representation of space remains elusive. Here we developed a method that, even without mobility (during Covid-19 lockdown), allows examining participants’ emotional representation of space and psychophysiological correlates. We gave participants blank maps of the region where they lived and asked them to apply shade where they had happy/sad memories, and where they wanted to go after the lockdown. They also completed self-reports on mental health and interoceptive awareness (appraisal of inner bodily sensations). By adapting neuroimaging methods, we examined shaded pixels instead of brain voxels to quantify where and how strong emotions are represented in space. The results revealed that happy memories were consistently associated with similar spatial locations. Yet, this mapping response varied as a function of participants’ mental health and interoceptive awareness. Interestingly, maps of happy memories and desired locations after lockdown overlay significantly with natural environments (vs. non-natural). These results suggest that our relationship with the environment relates to how we feel and appraise bodily sensations (i.e., allostasis in space). Our method may provide a spatially ecological marker for physical and mental disorders.

scholarly journals Spatially guided distractor suppression during visual search

2020 ◽  
Author(s):  
Tobias Feldmann-Wüstefeld ◽  
Marina Weinberger ◽  
Edward Awh
Keyword(s):  
Multivariate Analyses ◽  
Target Selection ◽  
Basic Question ◽  
Spatial Gradient ◽  
Selection Effects ◽  
Theta Band ◽  
Neural Signals ◽  
Past Work ◽  
Visual Encoding ◽  
Selection Of

AbstractPast work has demonstrated that active suppression of salient distractors is a critical part of visual selection. Evidence for goal-driven suppression includes below-baseline visual encoding at the position of salient distractors (Gaspelin and Luck, 2015) and neural signals such as the Pd that track the position and number of distractors in the visual field (Feldmann-Wustefeld and Vogel, 2019). One basic question regarding distractor suppression is whether it is inherently spatial or nonspatial in character. Indeed, past work has shown that distractors evoke both spatial (Theeuwes, 1992) and nonspatial forms of interference (Folk and Remington, 1998), motivating a direct examination of whether space is integral to goal-driven distractor suppression. Here, we provide clear evidence for a spatial gradient of suppression surrounding salient singleton distractors. Replicating past work, both reaction time and neural indices of target selection improved monotonically as the distance between target and distractor increased. Importantly, these target selection effects were paralleled by a monotonic decline in the amplitude of the Pd, an electrophysiological index of distractor suppression. Moreover, multivariate analyses revealed spatially selective activity in the theta band that tracked the position of the target and – critically – revealed suppressed activity at spatial channels centered on distractor positions. Thus, goal-driven selection of relevant over irrelevant information benefits from a spatial gradient of suppression surrounding salient distractors.

Implications of Ocular Kinematics for the Internal Updating of Visual Space

2001 ◽  
Vol 86 (4) ◽  
pp. 2112-2117 ◽  
Author(s):  
Michael A. Smith ◽  
J. Douglas Crawford
Keyword(s):  
Human Subjects ◽  
Three Dimensional ◽  
Visual Space ◽  
Fixation Light ◽  
Visual Targets ◽  
Spatial Locations ◽  
Central Fixation

Recent studies have suggested that during saccades cortical and subcortical representations of visual targets are represented and remapped in retinal coordinates. If this is correct, then the remapping processes must incorporate the noncommutativity of rotations. For example, our three-dimensional (3-D) simulations of the commutative vector-subtraction model of retinocentric remapping predicted centripetal errors in saccade trajectories between “remembered” eccentric targets, whereas our noncommutative model predicted accurate saccades. We tested between these two models in five head-fixed human subjects. Typically, a central fixation light appeared and two peripheral targets were flashed. With all targets extinguished, subjects were required to saccade to the remembered location of one of the peripheral targets and saccade between their remembered locations. Subjects showed minor misestimations of the spatial locations of targets, but failed to show the cumulative pattern of errors predicted by the commutative model. This experiment indicates that if targets are remapped in a retinal frame, then the remapping process also takes the noncommutativity of 3-D eye rotations into account. Unlike other noncommutative aspects of eye rotations that may have mechanical explanations, the noncommutative aspects of this process must be entirely internal.

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