Self-tuning Neurons and Firing Rate Set-points: The Role of Sleep in Gating Homeostatic Plasticity

Summary

Date: 
February 16, 2016 - 12:00pm
Location: 
Northwest 243
About the Speaker
Name: 
Gina Turrigiano (Brandeis)

Homeostatic mechanisms stabilize neural circuit function by keeping firing rates (FRs) within a set-point range, but whether individual neocortical neurons regulate firing around a cell-autonomous set-point, and whether this process is restricted to certain behavioral states such as sleep or wake, is unknown. I will start by discussing the mechanisms of synaptic scaling, a form of cell-autonomous homeostatic plasticty, and the role of this plasiticy in generating firing rate set-points in vivo. I will then discuss new work in which we follow the process of FR homeostasis in individual visual cortical neurons in freely behaving rodents as they cycled between sleep and wake states. When FRs are perturbed by visual deprivation, over time they returned precisely to a cell-autonomous set-point, and this restoration of firing occurred selectively during periods of active waking and was suppressed by sleep. Longer natural waking periods result in more FR homeostasis, as does artificially extending the length of waking. This exclusion of FR homeostasis from sleep raises the possibility that memory consolidation or some other sleep-dependent process is vulnerable to interference from homeostatic plasticity mechanisms.