Short-term sleep deprivation increases intrinsic excitability of prefrontal cortical neurons.

Short-term sleep deprivation (SD) has been shown to enhance cortical activity. However, alterations in the cellular excitability of cortical neurons following SD are not yet fully understood. The present study investigated the effects of 4-hour SD on pyramidal neurons in the prefrontal cortex (PFC) of rats using whole-cell patch-clamp recording. SD led to an increase in the initial slope of firing frequency-current curve and a decrease in frequency adaptation, which were reversed by recovery sleep (RS). Correspondingly, the total afterhyperpolarization (AHP) was reduced in the SD group and returned in the RS group. Furthermore, the component of AHP changed after SD seemed to be sensitive to Ca(2+). These observations indicate an enhancement in intrinsic excitability due to short-term SD, and suggest a role for Ca(2+)-dependent AHP in this change. The findings of the present study may provide a possible explanation for the SD-induced increase in cortical activity.