September 2017
Volume 17, Issue 10
Open Access
Vision Sciences Society Annual Meeting Abstract  |   August 2017
Task dependent modulation before, during and after visually evoked responses in human intracranial recordings
Author Affiliations
  • Leyla Isik
    Boston Children's Hospital, Harvard Medical School
    Massachusetts Institute of Technology
  • William Lotter
    Boston Children's Hospital, Harvard Medical School
    Harvard University
  • Nathan Crone
    Johns Hopkins School of Medicine
  • David Cox
    Massachusetts Institute of Technology
  • Nancy Kanwisher
    Massachusetts Institute of Technology
  • Wiliam Andreson
    Johns Hopkins School of Medicine
  • Gabriel Kreiman
    Boston Children's Hospital, Harvard Medical School
Journal of Vision August 2017, Vol.17, 983. doi:
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      Leyla Isik, William Lotter, Nathan Crone, David Cox, Nancy Kanwisher, Wiliam Andreson, Gabriel Kreiman; Task dependent modulation before, during and after visually evoked responses in human intracranial recordings. Journal of Vision 2017;17(10):983.

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      © ARVO (1962-2015); The Authors (2016-present)

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We can effortlessly answer many questions about the same visual stimulus. Standard models of visual recognition describe the sequence of processing steps that occur along the ventral visual stream during the first 150 ms after stimulus onset. When and where in the brain does processing start to depend on task? Here we examined the effect of task on visual processing by recording intracranial electrocorticography (ECoG) data from 1176 electrodes in ten epilepsy patients. Subjects were presented with synthetically generated face stimuli and were instructed to perform one of two possible two-alternative categorization tasks (Fig. 1): age (old/young) or gender (male/female). We measured the modulation of visually evoked responses by task before, during and after image presentation. The high gamma power in 50 visually-responsive electrodes differed between age and gender tasks, despite identical images being present in both tasks. Fourteen electrodes showed these task modulations early on, essentially concomitant with the onset of the visual responses. Thirty-seven electrodes showed late task modulation, after the initial visual evoked response. Intriguingly, we also observed 15 electrodes that showed sustained task modulation before image onset during the "Fixation" period (Fig. 1). These observations show that task modulates visual responses before, during, and after the initial visual response to the stimulus. This progression from pre-stimulus cuing to post-stimulus task representations provides an initial map of the sequence of operations used to transform identical visual inputs into different types of task related information.

Meeting abstract presented at VSS 2017


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