Effect of sleep deprivation on firing activity of hippocampal parvalbumin-expressing interneurons associated with trace eyeblink conditioning

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.