0128 SENSORY DEPRIVATION SUPPRESSES CORTICAL ACTIVITY IN A STATE AND ENVIRONMENT DEPENDENT MANNER

• Published in: Sleep (New York, N.Y.) N.Y.), 2017-04, Vol.40 (suppl_1), p.A48-A48
• Main Authors: Hengen, KB, Torrado Pacheco, A, Turrigiano, GG
• Format: Article
• Language: English
• ISSN: 0161-8105; 1550-9109
• DOI: 10.1093/sleepj/zsx050.127

Abstract Introduction: Monocular deprivation (MD), a well-established tool for studying plasticity in the visual cortex, induces a biphasic response in neural activity. Initially, neuronal firing rates (FRs) are suppressed by widespread Hebbian LTD. Following FR suppression in extended MD, homeostatic mechanisms restore spiking precisely to baseline levels. We recently demonstrated that the homeostatic return to the set-point is expressed during waking and not sleep. Here we address the role of arousal-states and environmental variables in gating the Hebbian depression of activity that characterizes early MD. Methods: To answer this question, we recorded activity from ensembles of cortical single units in juvenile rats (postnatal days 24–34) continuously for 10 days during a monocular deprivation (MD) paradigm. Results: As expected, amongst neurons that were “online” for the at least the first 6 days of the recording, firing rates dropped during early MD. Under normal conditions (12:12 light/dark cycles), automatically detected decreases in neuronal activity clustered around the ZT0 (“lights on”) and a significantly greater portion of the decrease occurred during light hours than dark. To further probe this causality of dark to light transitions in initiating the FR depression, we manipulated the light cycles of animals at critical points in early MD. Preliminary data suggest that animals must be awake for the FR suppression to start, but subsequent sleep/wake states are not correlated with changes in FR. Cortical activity in control hemispheres was stable across light/dark transitions. Conclusion: Taken with our previous data, these results suggest that individual forms of cortical plasticity have specific environmental and behavioral rules governing their expression and segregation. Support (If Any): 1K99NS089800-01 (KBH) R01EY014439 (GGT).