Abstract
Action selection computations are at the core of goal-directed behavior. Models of action selection suggest that
appropriate actions are selected through competition between potential choice options. Choice competition is
thought to occur across a multi-regional network that span frontal cortex, basal ganglia, and their downstream
circuits where neuronal population encoding potential choice options mutually inhibit each other to provide
opponent control of choice activity. Yet, how these brain regions interact to mediate this process and the loci of
choice competition remain unresolved. We recently identified a frontal cortico-basal-ganglia-superior colliculus
network responsible for action selection of directional licking during decision-making. Distinct neuronal
populations in this multi-regional network encode opposing choice options for lick direction and exhibit push-pull
dynamics prior to a licking movement, reflecting choice competition. Remarkably, activating or suppressing the
superior colliculus is sufficient to bidirectionally control the push-pull choice competition dynamics within the
network, implicating the superior colliculus as a key network node that can mediate choice competition. These
data suggest a working model in which circuits within frontal cortex and basal ganglia encode competition choice
options and they influence downstream superior colliculus in a topographically confined fashion to drive opponent
control of choice activity for specific actions. Leveraging a suite of recently developed technologies, this proposal
aims to precisely define a mesoscale cortico-basal-ganglia-colliculus network for action selection (Aim 1 and 2)
and directly probe the interactions of frontal cortex, basal ganglia, and superior colliculus to resolve the loci of
choice competition (Aim 3). The outcome will test longstanding theories of action selection and elucidate their
neural circuit implementations.