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Distinct roles for inhibitory neuron subtypes in cortical circuits : an examination of their structure, function, and connectivity

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dc.contributor.advisor Mriganka Sur. en_US
dc.contributor.author Runyan, Caroline A. (Caroline Anne) en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Brain and Cognitive Sciences. en_US
dc.date.accessioned 2012-10-10T15:43:45Z
dc.date.available 2012-10-10T15:43:45Z
dc.date.issued 2012 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/73772
dc.description Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Brain and Cognitive Sciences, 2012. en_US
dc.description "June 2012." Cataloged from PDF version of thesis. en_US
dc.description Includes bibliographical references. en_US
dc.description.abstract Parvalbumin-containing (PV+) neurons and somatostatin-containing (SOM+) neurons are two key cortical inhibitory cell classes that are poised to play distinct computational roles in cortical circuits: PV+ neurons form synapses on the perisomatic region near the spike initiation zone of target cells, while SOM+ neurons form synapses on distal dendrites. The goals of this thesis are to better understand the functional roles of these two cell types with four major lines of questioning. 1) When and how do PV+ and SOM+ neurons respond to visual stimuli? 2) How do inhibitory neurons obtain their response selectivity? 3) How do PV+ and SOM+ neurons affect the responses of their targets? and 4) What are the targets of PV+ and SOM+ neurons? We used Cre-lox recombination to introduce either fluorescent protein or channelrhodopsin to PV+ or SOM+ neurons, targeting these cells for two-photon targeted physiological recording and morphological reconstruction, or selectively stimulating the population of PV+ or SOM+ neurons or stimulating single PV+ or SOM+ neurons. We find diverse response properties within both groups, suggesting that further functional subclasses of PV+ and SOM+ neurons may exist. Furthermore, orientation selectivity was strongly correlated to dendritic length in PV+ neurons, whose orientation preferences matched the preferences of neighboring cells, implying that inhibitory neurons may obtain selectivity by spatially limiting their sampling of the local network. When we stimulated PV+ and SOM+ neurons, we found that they perform distinct inhibitory operations on their targets: PV+ neurons divide responses while SOM+ neurons subtract. Even single PV+ and SOM+ neurons were capable of suppressing responses of other cells in the local network, but their functional targeting was sparse and followed different rules of wiring: PV+ neurons functionally suppressed a higher percentage of cells that shared their own tuning, while SOM+ neurons seemed to target other neurons independently of their preferred orientations. By studying the response properties and functional impacts of PV+ and SOM+ neurons in the intact primary visual cortex, we have gained insight into what information these cells are carrying and how they contribute to the response properties of other cells, which apply to cortical circuits in general. en_US
dc.description.statementofresponsibility by Caroline A. Runyan. en_US
dc.format.extent 159 p. en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Brain and Cognitive Sciences. en_US
dc.title Distinct roles for inhibitory neuron subtypes in cortical circuits : an examination of their structure, function, and connectivity en_US
dc.type Thesis en_US
dc.description.degree Ph.D. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Brain and Cognitive Sciences. en_US
dc.identifier.oclc 810136551 en_US


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