UCSF

The nucleus reticularis thalami (nRT) is a sheet of GABAergic neurons that surrounds the thalamus and plays critical roles in sensory processing, attention, and sleep. Despite its central position within thalamocortical circuits, the mechanisms by which GABAergic signals converge and integrate within the nRT remain incompletely understood. The goal of this dissertation was to investigate the organization and functional consequences of GABAergic signaling in the nRT, particularly that originating from the external globus pallidus (GPe), across circuit and behavior. In Chapter 2, we characterized a previously underappreciated projection from the GPe to the nRT. We found that GPe input exerts opposing effects across nRT subregions due to regional differences in chloride homeostasis, resulting in either inhibitory or excitatory responses to GPe stimulation. These opposing effects produce distinct downstream consequences in thalamocortical (TC) circuits with a potential role in motor control, thereby identifying the GPe→nRT pathway as a non-canonical route through which the basal ganglia influence thalamic information processing. In Chapter 3, we examined how nRT and TC neurons transform synaptic inputs into spiking outputs using synthetic current injections. We found that the same input currents elicited distinct firing responses in nRT and TC neurons, demonstrating that intrinsic cellular properties play a critical role in shaping firing output.Together, these studies demonstrate that the functional consequences of GABAergic signaling in thalamic circuits are shaped by multiple interacting mechanisms, including chloride homeostasis and intrinsic neuronal properties.