Modularity of the microcircuitry of the lateral cortex of the mouse inferior colliculus

The inferior colliculus, or auditory midbrain, lies at the center of the auditory pathway and serves as a site of convergence and integration of acoustic information. In addition to its well-established functional role in processing sound information, one sub-region of the inferior colliculus, known as the lateral cortex, also receives massive input from somatosensory structures, and contains a network of anatomical modules that stain for GAD67 as well as other neurochemical markers. The purpose of the studies detailed in this dissertation was to further elucidate how the extrinsic inputs, local inputs, and outputs of the inferior colliculus interface with these neurochemical modules, and to understand how this particular microcircuitry might subserve acoustic and multisensory processing. In Chapter 2, we sought to better characterize the modules in the mouse inferior colliculus and determine if the connectivity of other neural structures with the lateral cortex is spatially related to the distribution of these neurochemical modules. Staining for GAD67 and other markers revealed a single modular network throughout the rostro-caudal extent of the mouse lateral cortex. Somatosensory inputs from the somatosensory cortex and dorsal column nuclei were found to terminate almost exclusively within these modular zones. However, projections from the auditory cortex and central nucleus of the inferior colliculus formed patches that interdigitate with the GAD67-positive modules. In Chapter 3, we used a combination of laser photostimulation of caged glutamate and patch clamp recordings to determine if the local connections in the lateral cortex also exhibit modularity. We found that modularity was cell-type specific, with extramodular cells largely receiving information from extramodular areas of the lateral cortex, and modular cells receiving information from both domains. In Chapter 4, we conducted a series of retrograde tract-tracing studies to determine if the outputs of the lateral cortex are also correlated with the distribution of neurochemical markers. We found that outputs to the superior colliculus and other regions of the inferior colliculus arise from cells in extramodular domains, while outputs to the medial division of the medial geniculate body arise from modular regions. Taken together, these results suggest that the lateral cortex of the mouse inferior colliculus exhibits connectional as well as neurochemical modularity, and may contain multiple partially segregated processing streams. These findings are further discussed in the context of the known functional roles of the lateral cortex in acoustico-motor processing.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Neuroscience

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2019

Author dc:creator

• Lesicko, Alexandria Marie

Contributors dc:contributor

• Llano, Daniel A.
• Christian, Catherine
• Wickesberg, Robert
• Galvez, Roberto

• inferior colliculus
• auditory
• midbrain
• multisensory convergence
• module

Statement dc:rights

• Copyright 2018 Alexandria Lesicko

Language dc:language

en

Handle dc:identifier

http://hdl.handle.net/2142/102784

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/102784