scholarly journals Categorical working memory codes in human visual cortex

2021 ◽  
Author(s):  
Chang Yan ◽  
Thomas B. Christophel ◽  
Carsten Allefeld ◽  
John-Dylan Haynes
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Neural Activity ◽  
Activity Patterns ◽  
Levels Of Abstraction ◽  
Cortical Hierarchy ◽  
Multiple Regions ◽  
Memory Contents ◽  
Memory Codes ◽  
Different Levels

Working memory contents are represented in neural activity patterns across multiple regions of the cortical hierarchy. It has remained unclear to which degree this reflects a specialization for different levels of abstraction. Here, we demonstrate that for color stimuli categorical codes are already present at the level of extrastriate visual cortex (V4 and VO1). Importantly, this categorical coding was observed during working memory, but not during perception.

scholarly journals Multiple states in ongoing neural activity in the rat visual cortex

PLoS ONE ◽  
2021 ◽  
Vol 16 (8) ◽  
pp. e0256791
Author(s):  
Daichi Konno ◽  
Shinji Nishimoto ◽  
Takafumi Suzuki ◽  
Yuji Ikegaya ◽  
Nobuyoshi Matsumoto
Keyword(s):  
Visual Cortex ◽  
Neural Activity ◽  
Activity Patterns ◽  
Electrode Array ◽  
Nonlinear Dimensionality Reduction ◽  
Neural Responses ◽  
Spontaneous Neural Activity ◽  
Custom Made ◽  
Visual Cortices ◽  
Freely Behaving

The brain continuously produces internal activity in the absence of afferently salient sensory input. Spontaneous neural activity is intrinsically defined by circuit structures and associated with the mode of information processing and behavioral responses. However, the spatiotemporal dynamics of spontaneous activity in the visual cortices of behaving animals remain almost elusive. Using a custom-made electrode array, we recorded 32-site electrocorticograms in the primary and secondary visual cortex of freely behaving rats and determined the propagation patterns of spontaneous neural activity. Nonlinear dimensionality reduction and unsupervised clustering revealed multiple discrete states of the activity patterns. The activity remained stable in one state and suddenly jumped to another state. The diversity and dynamics of the internally switching cortical states would imply flexibility of neural responses to various external inputs.

scholarly journals Testing the Efforts Model of Simultaneous Interpreting: An ERP Study

2017 ◽  
Author(s):  
Roman Koshkin ◽  
Yury Shtyrov ◽  
Alex Ossadtchi
Keyword(s):  
Working Memory ◽  
Neural Activity ◽  
Event Related Potential ◽  
Auditory Stimuli ◽  
Simultaneous Interpretation ◽  
Simultaneous Interpreting ◽  
Electrophysiological Evidence ◽  
Task Irrelevant ◽  
Different Levels

AbstractWe utilized the event-related potential (ERP) technique to study neural activity associated with different levels of working memory (WM) load during simultaneous interpretation (SI) in an ecologically valid setting. The amplitude of N1 and P1 components elicited by task-irrelevant tone probes was significantly modulated as a function of WM load but not the direction of interpretation. Furthermore, the latency of the N1 increased insignificantly with WM load. The P1 latency, however, mostly did not depend on either WM load or direction of interpretation. Larger negativity under lower WM loads suggests deeper processing of the auditory stimuli, providing tentative electrophysiological evidence in support of the Efforts Model of SI. Relationships between the direction of interpretation and median WM load are also discussed.

Anticipation of temporally structured events in the brain

2020 ◽  
Author(s):  
Caroline S Lee ◽  
Mariam Aly ◽  
Christopher Baldassano
Keyword(s):  
Human Brain ◽  
Neural Activity ◽  
Hidden Markov ◽  
Temporal Structure ◽  
Activity Patterns ◽  
Subjective Experiences ◽  
Movie Clip ◽  
Multiple Regions ◽  
Neural Event ◽  
The Brain

Learning about temporal structure is adaptive because it enables the generation of expectations. We examined how the brain uses experience in structured environments to anticipate upcoming events. During fMRI, individuals watched a 90-second movie clip six times. Using a Hidden Markov Model applied to searchlights across the whole brain, we identified temporal shifts between activity patterns evoked by the first vs. repeated viewings of the movie clip. In multiple regions throughout the cortex, neural activity patterns for repeated viewings shifted to preceded those of initial viewing by up to 12 seconds. This anticipation varied hierarchically in a posterior (less anticipation) to anterior (more anticipation) fashion. In a subset of these regions, neural event boundaries shifted with repeated viewing to precede subjective event boundaries by 5-7 seconds. Together, these results demonstrate a hierarchy of anticipatory signals in the human brain and link them to subjective experiences of events.

scholarly journals Sustained Neural Activity Patterns during Working Memory in the Human Medial Temporal Lobe

2007 ◽  
Vol 27 (29) ◽  
pp. 7807-7816 ◽  
Author(s):  
N. Axmacher ◽  
F. Mormann ◽  
G. Fernandez ◽  
M. X Cohen ◽  
C. E. Elger ◽  
...  
Keyword(s):  
Working Memory ◽  
Temporal Lobe ◽  
Neural Activity ◽  
Medial Temporal Lobe ◽  
Activity Patterns

scholarly journals The rat medial prefrontal cortex exhibits flexible neural activity states during the performance of an odor span task

2018 ◽  
Author(s):  
E De Falco ◽  
L An ◽  
N Sun ◽  
AJ Roebuck ◽  
Q Greba ◽  
...  
Keyword(s):  
Working Memory ◽  
Prefrontal Cortex ◽  
Medial Prefrontal Cortex ◽  
Neural Activity ◽  
Activity Patterns ◽  
Span Task ◽  
Neuron Activity ◽  
Neural Recordings ◽  
Odor Span ◽  
Abrupt Shifts

AbstractMedial prefrontal cortex (mPFC) activity is fundamental for working memory (WM), attention, and behavioral inhibition; however, a comprehensive understanding of the neural computations underlying these processes is still forthcoming. Towards this goal, neural recordings were obtained from the mPFC of awake, behaving rats performing an odor span task of WM capacity. Neural populations were observed to encode distinct task epochs and the transitions between epochs were accompanied by abrupt shifts in neural activity patterns. Putative pyramidal neuron activity increased significantly earlier in the delay for sessions where rats achieved higher spans. Furthermore, increased putative interneuron activity was only observed at the termination of the delay thus indicating that local processing in inhibitory networks was a unique feature to initiate foraging. During foraging, changes in neural activity patterns associated with the approach to a novel odor, but not familiar odors, were robust. Collectively, these data suggest that distinct mPFC activity states underlie the delay, foraging, and reward epochs of the odor span task. Transitions between these states enable successful performance in dynamic environments placing strong demands on the substrates of working memory.

scholarly journals Different states of priority recruit different neural codes in visual working memory

2018 ◽  
Author(s):  
Qing Yu ◽  
Bradley R. Postle
Keyword(s):  
Working Memory ◽  
Visual Cortex ◽  
Brain Regions ◽  
Focus Of Attention ◽  
Neural Representation ◽  
Stimulus Information ◽  
Brain Areas ◽  
Early Visual Cortex ◽  
A Site ◽  
Different Levels

AbstractWe tracked the neural representation of the orientation and the location of stimuli held in working memory at different levels of priority (“attended” and “unattended” memory items -- AMI and UMI), using multivariate inverted encoding models of human fMRI. Although representation of the orientation of the AMI and of the UMI could be reconstructed in several brain regions, including in early visual and parietal regions, the identity of the UMI was actively represented in early visual cortex in a distinct “reversed” code, suggesting this region as a site of the focus of attention to nonspatial stimulus information. The location of stimuli was also broadly represented, although only in parietal cortex was the location of the UMI represented in a reversed code. Our results suggest that a common recoding operation may be engaged, across stimulus dimensions and brain areas, to retain information in working memory while outside the focus of attention.

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