Thalamocortical Temporal Dynamics Underlying Memory Consolidation during NREM Sleep

Project Summary Our long-term objective is to determine how thalamic networks contribute to memory consolidation. The goal of this project is to investigate the basic mechanisms by which the dynamics of spike activity in cognitive thalamic networks contribute to memory consolidation. During non-rapid eye movement (NREM) sleep, spindle oscillations in thalamocortical networks and ripple oscillations in the hippocampus facilitate memory consolidation. However, the precise role of thalamic spindle activation dynamics in memory consolidation remains unclear. We aim to answer two basic questions. First, we will use optogenetics and electrophysiology to induce spindle-like activity in the thalamus of rats after training them in a memory task to understand how different patterns of thalamocortical activation facilitate sleep-dependent consolidation. Complementary computational modeling will help us understand the impact of spindle-like thalamic activation on cortical circuits and spindles. Second, we aim to determine how the thalamus facilitates hippocampal ripple oscillations and memory consolidation. We will use behavioral testing, extracellular recordings, and closed-loop optogenetics, to control thalamic spiking activity after detection of ripple oscillations in the hippocampus. This approach will enable us to assess the causal contribution of the thalamus to the fundamental NREM sleep oscillations that facilitate hippocampal-neocortical interactions and sleep-dependent memory consolidation. Understanding the role of thalamocortical neural dynamics in memory consolidation is clinically relevant for developing new interventions for neuropsychiatric disorders are associated with sleep and memory disruption.