The thalamus is a subcortical structure that has been popularly coined as the “relay center” of the brain due to its central role in both first-order and executive function. Like a gate, the thalamus can redirect, initiate, sustain, and switch cortical activity. This is accomplished by the topographically organized pathways the thalamus and cortex reciprocally share. These pathways are categorized into two types of circuits; core and matrix. Core pertains to parvalbumin-positive thalamocortical projecting neurons, usually carrying sensory information. On the other hand, matrix pertains to the calbindin-positive network of widespread thalamocortical projecting neurons, typically related to association processes. The integration of both circuits allows for complex and dynamic interactions, including regulation of consciousness, alertness, perception, emotion, and action. The matrix-core theory was first proposed by Edward Jones (1998) and neuroscientists have since developed hypotheses as to how the distinct neurochemical/molecular systems may be linked to cognition. In this paper we discuss the proportions of parvalbumin- and calbindin-positive core and matrix pathways seen traveling through and innervating different regions of the thalamic reticular nucleus (TRN), an inhibitory nucleus directly superficial to the thalamus, that filters thalamocortical communications. Attention modulation, memory consolidation, and consciousness are a few cognitive functions regulated by the reticular nucleus, however, little is known about the extent in which it aids in these executive processes, the molecular mechanisms underlying them, or how its architecture may differentially affect sensory and association pathways. Even though it was thought that the TRN is organized homogeneously, recent findings suggest regional molecular specializations. Based on this, and the organization of the thalamus in distinct core and matrix circuits, we hypothesize that core and matrix thalamocortical projections will target the TRN in a topographical manner at different ratios, defining functionally, connectionally, and molecularly distinct and heterogeneous TRN sectors. For both primates and non-human primates, we predict there to be clear similarities in the reciprocal innervating patterns of the TRN as well as specific immunoreactive protein concentrations that rapidly or gradually change along its dorsal-ventral extent. / 2024-05-20T00:00:00Z
| Identifer | oai:union.ndltd.org:bu.edu/oai:open.bu.edu:2144/44473 |
| Date | 20 May 2022 |
| Creators | Son, Jillianne |
| Contributors | Zikopoulos, Vasileios, Yazdanbakhsh, Arash |
| Source Sets | Boston University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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