Investigating the Anatomical Basis for Streams in the Mouse Visual Cortex
Abstract
Examining the organization of the visual cortex can help show how visual processing
is accomplished. For instance, a major organizational property of the primate visual
cortex is the division of the higher visual areas (HVAs) into separate streams with
high connectivity and similar functional properties. These streams allow for parallel
processing of functionally distinct visual phenomena, with the ventral stream focusing
on object recognition and the dorsal stream on localization and movement coordination.
While some mechanisms for the segregation of
streams from primary visual cortex (V1) to the HVAs are known, such as the clustering
of neurons feeding into separate streams within specialized layers, the architecture
at the level of single cells is not known. Understanding this anatomical organization
is important for predicting how information is distributed, and shared, among the
HVAs. In the mouse, studies examining the reciprocal connectivity between visual areas,
especially Burkhalter (Wang, Sporns, & Burkhalter, 2012), have suggested a stream
organization similar to that seen in primates. Modern genetic techniques in the mouse
present an opportunity to study the anatomical organization and functional specializations
that contribute to parallel processing in streams. Towards this goal, we
set out to understand which neuronal populations in mouse V1 might participate in
each stream and their degree of anatomical segregation.
Here we tested the hypothesis that there is anatomical specificity, at the level of
both
laminar populations and individual neurons, in the makeup of streams originating in
V1. Anatomical specificity was assessed by quantifying the number of neurons in each
V1 lamina projecting to each HVA and by finding the probability that V1 neurons project
to multiple HVAs. Although laminar specificity did not differ among the HVAs, there
was a trend of V1 neurons with multiple projection targets synapsing onto HVAs in
a preferred stream. Though these findings do not reveal the anatomical basis for streams
seen in the primate cortex, they reveal a mechanism for sharing information among
streams that could be crucial to understanding these modules’ role in visual processing.
Future studies could investigate the functional properties of neurons with multiple
projections to HVAs in a certain visual stream and determine physiological aspects
that could contribute to sharing of information among streams with different response
properties. These studies will ultimately reveal how the visual system distributes
information into streams made up of highly interconnected HVAs, and how these networks
are used to guide behavior.
Type
Honors thesisDepartment
BiologyPermalink
https://hdl.handle.net/10161/14251Citation
Hoffman, Gary (2017). Investigating the Anatomical Basis for Streams in the Mouse Visual Cortex. Honors thesis, Duke University. Retrieved from https://hdl.handle.net/10161/14251.Collections
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