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Updated: May 31, 2026

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation
Published on: May 23, 2017
Distinct functions for direct and transthalamic corticocortical connections
S Murray Sherman1, R W Guillery
1Department of Neurobiology, The University of Chicago, 947 E. 58th St., MC 0926, 316 Abbott, Chicago, IL 60637, USA. msherman@bsd.uchicago.edu
Abstract:
Essentially all cortical areas receive thalamic inputs and send outputs to lower motor centers. Cortical areas communicate with each other by means of direct corticocortical and corticothalamocortical pathways, often organized in parallel. We distinguish these functionally, stressing that the transthalamic pathways are class 1 (formerly known as "driver") pathways capable of transmitting information, whereas the direct pathways vary, being either class 2 (formerly known as "modulator") or class 1. The transthalamic pathways provide a thalamic gate that can be open or closed (and otherwise more subtly modulated), and these inputs to the thalamus are generally branches of axons with motor functions. Thus the transthalamic corticocortical pathways that can be gated carry information about the cortical processing in one cortical area and also about the motor instructions currently being issued from that area and copied to other cortical areas.
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