Venue: Centre Broca
Yoshihisa Tachibana
Kobe University, Japan
Invited by Thomas Boraud (IMN)
Title
Movement disorders: the imbalance between hyperdirect and direct pathways in the basal ganglia
Abstract
The basal ganglia (BG) play a crucial role in motor control, with the subthalamic nucleus (STN) and the striatum (Str) serving as major input stations receiving signals from a wide variety of cortical areas. These structures project to the output nuclei of the BG, the internal segment of the globus pallidus (GPi) and the sunstantia nigra pars reticulata (SNr), forming the cortico-STN-GPi/SNr “hyperdirect” pathway and the cortico-Str-GPi/SNr “direct” pathway. This seminar explores the hypothesis that the execution of motor actions is highly sophisticated when information processing via the hyperdirect and direct pathways is well-balanced. First, I will summarize the primate models of hyperkinetic disorder, specifically hemiballism, and hypokinetic disorder, exemplified by Parkinson’s disease. Insights into abnormal neuronal processing in cortico-BG circuits are discussed to enhance our understanding of the pathophysiology underlying these disorders. Additionally, I also demonstrate our recent findings from a mouse tic model, shedding light on the pathophysiology of tic disorders. I finally propose the functional role of the external segment of the globus pallidus (GPe) in motor control. Specifically, I would like to suggest that the GPe may play a crucial role in balancing the « hyperdirect » and « direct » pathways, contributing to the coordination of motor actions.