UCSF

Locomotion is a behavior essential for survival. It is important for guiding goal-directed approach towards desired outcomes and avoidance of aversive stimuli. To this end, a large number of processes in the brain are both regulated by and serve to inform the locomotor behavior of animals. Here, we attempt to define the neural circuits underlying locomotor control, the associated changes that locomotion has upon brain states, and the neurobiological basis of locomotor decisions. In Chapter 1, we describe what is known regarding the neural circuits guiding locomotor behaviors. We provide background also regarding the known mechanisms that guide changes in brain states and are associated with locomotion. We then touch upon recent literature attempting to understand how information is used to guide decision-making to better understand the specific problem of how locomotor decisions are made. In Chapter 2, we then present novel findings, identifying brainstem circuits that control locomotion and concurrently regulate visual processing of information in the cortex through the basal forebrain. These findings may apply to other networks beyond the visual system and form a general mechanism by which various brain regions are modulated by behavioral state. In Chapter 3, we demonstrate that these brainstem circuits are under the regulation of the basal ganglia. These studies identify a conserved, phylogenetically ancient pathway for guiding locomotion that may exist in all vertebrates and represent one of the earliest functions of the basal ganglia system. In chapter 4, we leverage our understanding of the basal ganglia pathways for locomotor control to understand the processes of goal-directed decision-making. In chapter 5, we find that the ventral striatal shares a parallel organization to the dorsal striatum for implementing reinforcement learning to guide future locomotor decision-making. These studies into the basis of goal-directed locomotor behaviors may elucidate general principles for decision-making. Collectively, these results demonstrate control systems for locomotion are deeply interconnected with a diverse array of processes throughout the brain that guide goal-directed locomotor behaviors.