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.

[Research on a new method and index for evaluating cardiac function of the athletes].

OBJECTIVE: To explore the new indexes and new methods for the noninvasive measuring and evaluating cardiac function detection of the athletes. METHODS: Heart sound signals were sampled randomly from 81 students in physical education department (experiment group) and 41 students in general departments (control group) after completing designed workload during step-climbing exercise, the contrast study on heart rate, D/S ratio as well as the S1/S2 ratio of students from physical education and general department has been conducted. RESULTS: In the resting state, the physical education department students' heart rate and D/S ratio was 66 +/- 8.7 and 2.04 +/- 0.33 respectively; general department students' heart rate and D/S ratio was 71 +/- 8.0 and 1.82 +/- 0.27 respectively. In the whole exercise, the physical education department students S1/S2 ratio was 7.34 +/- 4.04; general department students S1/S2 ratio was 5.22 +/- 2.38. CONCLUSION: Students from physical education department have higher level of cardiac reserve than that of students from general department. The method can evaluate cardiac reserve for athletes and general persons, and provide a new quantity evaluation index for selecting athletes and evaluating cardiac function of general persons.