Hippocampal theta power pressure builds over non-REM sleep and dissipates within REM sleep episodes.

Hippocampal theta power pressure builds over non-REM sleep and dissipates within REM sleep episodes. Arch Ital Biol. 2018 Sep 01;156(3):112-126 Authors: Bjorness TE, Booth V, Poe GR Abstract The theta rhythm during waking has been associated with voluntary motor activity and learning processes involving the hippocampus. Theta also occurs continuously during rapid eye movement (REM) sleep where it likely serves memory consolidation. Theta amplitude builds across wakefulness and is the best indicator of the homeostatic need for non-REM (NREM) sleep. Although REM sleep is homeostatically regulated independently of NREM sleep, the drivers of REM sleep regulation are under debate. The dynamics of theta within REM sleep bouts have not been thoroughly explored. We equipped 20 male rats with sleep instrumentation and hippocampal electrodes to measure theta across normal sleep/waking periods over the first 4 h of the sleep phase on two consecutive days. We found that theta power decreased by a third, on average, within individual REM sleep bouts, but recovered between bouts. Thus, there was no general decline in theta power across the duration of the recording period or between days. The time constant of theta power decline within a REM sleep bout was the same whether the bout was short, midlength, or long, and did not predict the behavioral state immediately following the REM sleep bout. Interestingly, the more time spent in NREM sleep prior...
Source: Archives Italiennes de Biologie - Category: Neuroscience Tags: Arch Ital Biol Source Type: research