9/27/2024 Ayman Aljishi: Memory Trace Reactivation during Coordinated Sleep Oscillations in Macaques
Neuroscience Brown Bag
Ayman Aljishi
Graduate Student, Hoffman Lab
Date: Friday, September 27, 2024
Time: 1:25PM-2:15PM
Location: 316 Wilson Hall
Memory Trace Reactivation during Coordinated Sleep Oscillations in Macaques
Non-rapid eye-movement (NREM) sleep is important for the formation of durable associative memories. One theorized role relies on the synchronization between two sleep oscillations: spindles (at 10-16 Hz) and hippocampal sharp-wave ripples (SWRs, 100-180 Hz in primates). In rodents, these oscillations index the sleep states when task-related neural ensemble “cell assemblies” reactivate. This offline reactivation is important for memory durability, and its associated sleep oscillations reflect neural circuit dynamics that are thought to organize and modify brain-wide cell assemblies. In primates, including humans, these canonical sleep oscillations are conserved; however, it is unclear whether the coordination of these rhythms also modulates cell assembly reactivation. To address this, we wirelessly recorded local field potentials (LFPs) and ensemble spiking activity during sequenced-associative learning and subsequent overnight sleep in two female macaques implanted with probes in the hippocampus and in extrahippocampal areas. First, I will describe the characteristics and interactions of detected hippocampal CA1 SWRs and spindles from the LFP in macaques. Then I will show their relation to reactivating cell assemblies identified with applied component analysis. Although the analyses are ongoing, I will discuss how selective reactivation of assemblies aligned to oscillatory states could impact memory stability. More generally, the dynamics of cell assembly reactivation during critical hippocampo-neocortical network events could provide insights into a possibly unique role of hippocampal ensembles in shaping the location and organization of memory traces throughout the cortex of human and non-human primates.
Questions? Contact Jon Kaas