To investigate the effects of sleep deprivation on the firing activity of hippocampal parvalbumin-expressing interneuron (PV-IN) of mice during trace eyeblink conditioning (tEBC) training and during recovery sleep.

A total of 15 PV-Cre mice were randomly assigned into a sleep deprivation group (n=8) and a control group (n=7). After daily tEBC training, the sleep deprivation group experienced 1.5 h of sleep deprivation followed by 1.5 h of recovery sleep, and the control group mice were allowed to sleep freely, for 5 consecutive days. Multichannel recording and optogenetic techniques was applied to identify the hippocampal PV-IN in vivo.

The sleep deprived mice failed to show significant increase in the incidence of conditioned eyeblink response (CR) across 5 training days (P>0.05). On training days 3~5, the CR incidence was significantly lower in the sleep deprived mice than the control mice (P<0.05). The enhancement of conditioned stimulus (CS)-evoked firing activity in hippocampal PV-INs during tEBC training was significantly lower in the sleep deprived mice when compared to the control mice (P<0.05). The sleep deprived mice obtained notably strengthened firing activity of hippocampal PV-INs peri sharp wave ripple events during recovery sleep period when compared with the pre-training sleep period (P<0.05), and the enhancement was remarkably greater than that in the control mice (P<0.05). Sleep deprivation had no obvious effects on the firing activity of hippocampal non PV-IN during either tEBC training or recovery sleep (P>0.05).

Sleep deprivation produces dual effects on the firing activities of hippocampal PV-INs during tEBC training and recovery sleep. These effects may be the cellular mechanisms of tEBC memory formation and consolidation disorders caused by sleep deprivation.