Spatial specificity of working memory representations in the early visual cortex

Abstract Humans can construct rich subjective experience even when no information is available in the external world. Here, we investigated the neural representation of purely internally generated stimulus-like information during visual working memory. Participants performed delayed recall of oriented gratings embedded in noise with varying contrast during fMRI scanning. Their trialwise behavioral responses provided an estimate of their mental representation of the to-be-reported orientation. We used multivariate inverted encoding models to reconstruct the neural representations of orientation in reference to the response. We found that response orientation could be successfully reconstructed from activity in early visual cortex, even on 0% contrast trials when no orientation information was actually presented, suggesting the existence of a purely internally generated neural code in early visual cortex. In addition, cross-generalization and multidimensional scaling analyses demonstrated that information derived from internal sources was represented differently from typical working memory representations, which receive influences from both external and internal sources. Similar results were also observed in intraparietal sulcus, with slightly different cross-generalization patterns. These results suggest a potential mechanism for how externally driven and internally generated information is maintained in working memory.

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Working memory representations in visual cortex mediate distraction effects

Nature Communications ◽

10.1038/s41467-021-24973-1 ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Grace E. Hallenbeck ◽

Thomas C. Sprague ◽

Masih Rahmati ◽

Kartik K. Sreenivasan ◽

Clayton E. Curtis

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Visual Memory ◽

Neural Representation ◽

Association Cortex ◽

Catastrophic Loss ◽

Visual Tasks ◽

Early Visual Cortex ◽

Memory Representations ◽

The Impact

AbstractAlthough the contents of working memory can be decoded from visual cortex activity, these representations may play a limited role if they are not robust to distraction. We used model-based fMRI to estimate the impact of distracting visual tasks on working memory representations in several visual field maps in visual and frontoparietal association cortex. Here, we show distraction causes the fidelity of working memory representations to briefly dip when both the memorandum and distractor are jointly encoded by the population activities. Distraction induces small biases in memory errors which can be predicted by biases in neural decoding in early visual cortex, but not other regions. Although distraction briefly disrupts working memory representations, the widespread redundancy with which working memory information is encoded may protect against catastrophic loss. In early visual cortex, the neural representation of information in working memory and behavioral performance are intertwined, solidifying its importance in visual memory.

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Working Memory Representations in Visual Cortex Mediate the Effects of Distraction

10.1101/2021.02.01.429259 ◽

2021 ◽

Author(s):

Grace E. Hallenbeck ◽

Thomas C. Sprague ◽

Masih Rahmati ◽

Kartik K. Sreenivasan ◽

Clayton E. Curtis

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Neural Representation ◽

Association Cortex ◽

Neural Decoding ◽

Memory Errors ◽

Catastrophic Loss ◽

Early Visual Cortex ◽

Memory Representations ◽

The Impact

SUMMARYAlthough the contents of working memory (WM) can be decoded from activity in visual cortex, these representations may play a limited role if they are not robust to distraction. Here, we used model-based fMRI to estimate the impact that a distracting visual task had on WM representations in several visual field maps in visual and frontoparietal association cortex. Distraction caused the fidelity of WM representations in all maps to briefly dip when both the memorandum and distractor were jointly encoded by the population activities. Moreover, distraction induced small biases in memory errors which were predicted by biases in neural decoding in early visual cortex, but not other regions. Although distraction briefly disrupts WM representations, the widespread redundancy with which WM information is encoded may protect against catastrophic loss. In early visual cortex, nonetheless, the neural representation of information in WM and behavioral performance were intertwined, solidifying its importance in memory.

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Anatomy of early visual cortex predicts visual working memory capacity

Journal of Vision ◽

10.1167/13.9.1349 ◽

2013 ◽

Vol 13 (9) ◽

pp. 1349-1349

Author(s):

J. Bergmann ◽

E. Genc ◽

A. Kohler ◽

W. Singer ◽

J. Pearson

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Visual Working Memory ◽

Working Memory Capacity ◽

Memory Capacity ◽

Early Visual Cortex

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The limited contribution of early visual cortex in visual working memory for surface roughness

10.31234/osf.io/ys3a5 ◽

2020 ◽

Author(s):

Munendo Fujimichi ◽

Hiroki Yamamoto ◽

Jun Saiki

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Visual Working Memory ◽

Brain Activity ◽

Visual Representations ◽

Brain Regions ◽

Daily Lives ◽

Early Visual Cortex ◽

Roughness Discrimination ◽

Visual Properties

Are visual representations in the human early visual cortex necessary for visual working memory (VWM)? Previous studies suggest that VWM is underpinned by distributed representations across several brain regions, including the early visual cortex. Notably, in these studies, participants had to memorize images under consistent visual conditions. However, in our daily lives, we must retain the essential visual properties of objects despite changes in illumination or viewpoint. The role of brain regions—particularly the early visual cortices—in these situations remains unclear. The present study investigated whether the early visual cortex was essential for achieving stable VWM. Focusing on VWM for object surface properties, we conducted fMRI experiments while male and female participants performed a delayed roughness discrimination task in which sample and probe spheres were presented under varying illumination. By applying multi-voxel pattern analysis to brain activity in regions of interest, we found that the ventral visual cortex and intraparietal sulcus were involved in roughness VWM under changing illumination conditions. In contrast, VWM was not supported as robustly by the early visual cortex. These findings show that visual representations in the early visual cortex alone are insufficient for the robust roughness VWM representation required during changes in illumination.

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Shared Representations for Working Memory and Mental Imagery in Early Visual Cortex

Current Biology ◽

10.1016/j.cub.2013.05.065 ◽

2013 ◽

Vol 23 (15) ◽

pp. 1427-1431 ◽

Cited By ~ 192

Author(s):

Anke Marit Albers ◽

Peter Kok ◽

Ivan Toni ◽

H. Chris Dijkerman ◽

Floris P. de Lange

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Mental Imagery ◽

Shared Representations ◽

Early Visual Cortex

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Visual working memory and attention in early visual cortex

Journal of Vision ◽

10.1167/6.6.1091 ◽

2010 ◽

Vol 6 (6) ◽

pp. 1091-1091

Author(s):

S. Offen ◽

D. Schluppeck ◽

D. J. Heeger

Keyword(s):

Working Memory ◽

Visual Cortex ◽

Visual Working Memory ◽

Memory And Attention ◽

Early Visual Cortex

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The limited contribution of early visual cortex in visual working memory for surface roughness

Experimental Brain Research ◽

10.1007/s00221-020-05881-0 ◽

2020 ◽

Vol 238 (10) ◽

pp. 2189-2197 ◽

Cited By ~ 1

Author(s):

Munendo Fujimichi ◽

Hiroki Yamamoto ◽

Jun Saiki

Keyword(s):

Working Memory ◽

Surface Roughness ◽

Visual Cortex ◽

Visual Working Memory ◽

Early Visual Cortex

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Population Dynamics of Early Visual Cortex during Working Memory

Journal of Cognitive Neuroscience ◽

10.1162/jocn_a_01196 ◽

2018 ◽

Vol 30 (2) ◽

pp. 219-233 ◽

Cited By ~ 4

Author(s):

Masih Rahmati ◽

Golbarg T. Saber ◽

Clayton E. Curtis

Keyword(s):

Working Memory ◽

Population Dynamics ◽

Visual Cortex ◽

Parietal Cortex ◽

Visual Stimulus ◽

Visual Stimulation ◽

Brain Activity ◽

Top Down ◽

Population Activity ◽

Early Visual Cortex

Although the content of working memory (WM) can be decoded from the spatial patterns of brain activity in early visual cortex, how populations encode WM representations remains unclear. Here, we address this limitation by using a model-based approach that reconstructs the feature encoded by population activity measured with fMRI. Using this approach, we could successfully reconstruct the locations of memory-guided saccade goals based on the pattern of activity in visual cortex during a memory delay. We could reconstruct the saccade goal even when we dissociated the visual stimulus from the saccade goal using a memory-guided antisaccade procedure. By comparing the spatiotemporal population dynamics, we find that the representations in visual cortex are stable but can also evolve from a representation of a remembered visual stimulus to a prospective goal. Moreover, because the representation of the antisaccade goal cannot be the result of bottom–up visual stimulation, it must be evoked by top–down signals presumably originating from frontal and/or parietal cortex. Indeed, we find that trial-by-trial fluctuations in delay period activity in frontal and parietal cortex correlate with the precision with which our model reconstructed the maintained saccade goal based on the pattern of activity in visual cortex. Therefore, the population dynamics in visual cortex encode WM representations, and these representations can be sculpted by top–down signals from frontal and parietal cortex.

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