Robert Schmidt, BrainLinks-BrainTools / Bernstein Center Freiburg

A two-step model of action suppression based on basal ganglia neurophysiology

Classic basal ganglia models describe the globus pallidus (GP) as a
homogeneous structure that relays information from the striatum to the
subthalamic nucleus and the substantia nigra pars reticulata. In
contrast to this, recently discovered arkypallidal neurons ("Arky") in
GP provide vast inhibitory back-projections to the striatum. Therefore,
GP might strongly shape the output of the striatum in both normal and
pathological behavior, e.g. by spreading beta oscillations in
Parkinson's disease. To identify functional roles of Arky neurons, we
investigated the activity patterns of Arky and other GP neurons during a
Stop signal task, which requires the abrupt cancellation of an imminent
action. We first establish that Arky neurons can be identified through
their distinctive firing properties across the natural sleep/wake cycle.
We then show that, unlike other sets of basal ganglia neurons, an Arky
subpopulation responds strongly and selectively to Stop cues. The timing
of this Stop response corresponds closely to the suppression of
developing Go-related activity in striatum. Our results support a
two-step model of action suppression, whereby actions-in-preparation are
first paused via a subthalamic-nigral pathway, then canceled via the
selective GABAergic Arky projections to striatum.

Organized by

John-Dylan Haynes