ELSC News

Article of the Month, October 2017 (Deouell's lab)

October 2, 2017

Cortical representation of persistent visual stimuli

Authors: Gerber et al. (Leon Deouell's lab)
Published in NeuroImage on August 2017

 

How the brain processes visual input is typically studied by presenting brief visual stimuli and investigating the neural response they elicit. This approach has yielded vast amount of information, but it covers only moments of abrupt change, which correspond to a fraction of the time course of perception. Thus we know very little about how visual objects are represented in the brain the moments beyond their onset.

This study addresses this question by showing patients implanted with intracranial electrodes images for durations ranging from 0.3 to 1.5 seconds, and asking to what degree the neural response in each recording site (measured as changes in high frequency broadband power) is reliably sustained for the duration of each stimulus. The results show that this reliability is highest in early visual cortex, and gradually diminishes along the ventral stream such that it is lowest in downstream regions. Surprisingly, it is these downstream regions that are most category-selective. Thus, the response in high-level areas is more informative about stimulus content, but less informative about its moment-to-moment presence in the visual field. 

 

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