Advanced search options

Advanced Search Options 🞨

Browse by author name (“Author name starts with…”).

Find ETDs with:

in
/  
in
/  
in
/  
in

Written in Published in Earliest date Latest date

Sorted by

Results per page:

You searched for +publisher:"Harvard University" +contributor:("Kreiman, Gabriel xmlui.authority.confidence.description.cf_uncertain"). One record found.

Search Limiters

Last 2 Years | English Only

No search limiters apply to these results.

▼ Search Limiters


Harvard University

1. Trott, Alexander. Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback.

Degree: PhD, 2016, Harvard University

How does the brain form a useful representation of its external environment from the astoundingly complex patterns of sensory signals it receives? This question has motivated the field of systems neuroscience for decades. Our current understanding stems from the discovery that sensory cortex is a hierarchical system, where the behaviorally relevant information that is only implicit in sensory inputs is made explicit through sequential stages of processing. The connections between cortical areas that create this processing sequence are abundantly reciprocal, such that information flows from lower- to higher-order areas through feedforward connections and in the reverse direction through feedback connections. Despite the anatomical abundance of feedback, its role in computation is poorly understood. Recent evidence suggests that the role of feedback relates to contextual modulation, a process by which neural responses to sensory information are shaped by the behavioral or stimulus setting in which that information arrives. A canonical example of contextual modulation is surround suppression in primary visual cortex (V1). Here, we demonstrate the richness and specificity with which the stimulus surround tailors the representations of context embedded stimuli in V1 of awake macaque monkeys. In addition, we reversibly inactivated cortical areas V2/V3 and their feedback projections to V1 to identify a possible role of feedback in mediating these sophisticated forms of modulation. The effects of feedback inactivation were observed to differ considerably between subjects, but our overall findings suggest that feedback contributes to divisive modulation in a manner that, as shown by previous theoretical work, reflects optimal adaptation to the statistics of natural stimuli. In addition, we observed that noise correlations in V1 were restructured from day to day in a stimulus-dependent and feedback-dependent manner. We use these findings to propose future experiments that will allow us to better understand the diversity of inactivation effects across subjects as well as how the precise network-level signatures of contextual modulation depend on feedback. We expect that these details will provide critical insights towards an understanding of the role of cortico-cortical feedback in sensory processing and cortical computation.

Medical Sciences

Advisors/Committee Members: Kreiman, Gabriel xmlui.authority.confidence.description.cf_uncertain (advisor), Assad, John (committee member), Andermann, Mark (committee member), Sheinberg, David (committee member).

Subjects/Keywords: Biology; Neuroscience

Record DetailsSimilar RecordsGoogle PlusoneFacebookTwitterCiteULikeMendeleyreddit

APA · Chicago · MLA · Vancouver · CSE | Export to Zotero / EndNote / Reference Manager

APA (6th Edition):

Trott, A. (2016). Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback. (Doctoral Dissertation). Harvard University. Retrieved from http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493254

Chicago Manual of Style (16th Edition):

Trott, Alexander. “Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback.” 2016. Doctoral Dissertation, Harvard University. Accessed October 24, 2020. http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493254.

MLA Handbook (7th Edition):

Trott, Alexander. “Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback.” 2016. Web. 24 Oct 2020.

Vancouver:

Trott A. Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback. [Internet] [Doctoral dissertation]. Harvard University; 2016. [cited 2020 Oct 24]. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493254.

Council of Science Editors:

Trott A. Contextual Modulation of Early Visual Processing and the Role of Cortico-Cortical Feedback. [Doctoral Dissertation]. Harvard University; 2016. Available from: http://nrs.harvard.edu/urn-3:HUL.InstRepos:33493254

.