Stress-free automatic sleep deprivation using air puffs

Abstract

Background Sleep deprivation via gentle handling is time-consuming and personnel-intensive. New Method We present here an automated sleep deprivation system via air puffs. Implanted EMG and EEG electrodes were used to assess sleep/waking states in six male Sprague-Dawley rats. Blood samples were collected from an implanted intravenous catheter every 4 hours during the 12-hour light cycle on baseline, 8 hours of sleep deprivation via air puffs, and 8 hours of sleep deprivation by gentle handling days. Results The automated system was capable of scoring sleep and waking states as accurately as our offline version (~90% for sleep) and with sufficient speed to trigger a feedback response within an acceptable amount of time (1.76 s). Manual state scoring confirmed normal sleep on the baseline day and sleep deprivation on the two manipulation days (68% decrease in non-REM, 63% decrease in REM, and 74% increase in waking). No significant differences in levels of ACTH and corticosterone (stress hormones indicative of HPA axis activity) were found at any time point between baseline sleep and sleep deprivation via air puffs. Comparison with Existing Method There were no significant differences in ACTH or corticosterone concentrations between sleep deprivation by air puffs and gentle handling over the 8-hour period. Conclusions Our system accurately detects sleep and delivers air puffs to acutely deprive rats of sleep with sufficient temporal resolution during the critical 4-5 h post learning sleep-dependent memory consolidation period. The system is stress-free and a viable alternative to existing sleep deprivation techniques.

A role for spindles in the onset of rapid eye movement sleep

“…We further showed that optogenetic activation of TRN VGAT neurons, or TRN VGAT -AD projections, is sufficient to induce spindles and facilitate NREM to REM sleep transitions. These later results are consistent with our finding that spindle-rich EEG during NREM sleep predicts the onset of REM sleep, as previously suggested 21 , 22 . Of note, gender-specific effects of the “spindle–REM sleep” relationship due to high spindle rate described in female rodents as compared to males 55 warrant further investigation.…”

“…Consistent with scalp electroencephalography (EEG) recordings, fMRI studies confirmed the activation of distinct brain regions associated with slow and fast spindles 20 , suggesting two different mechanisms of generation and offering the possibility of distinct functions. Spindle-rich EEG during NREM sleep—sometimes considered as distinct stage of NREM sleep 21 , 22 —has been proposed to reflect sleep stability in rodents and human 14 , 23 , 24 , and often precedes REM sleep transition, yet, the implication of spindles in REM sleep onset remains unclear. Furthermore, a correlative role for spindles in memory consolidation, intelligence, and cognition has been proposed 25 – 29 , and further confirmed by increased motor memory consolidation upon enhancement of spindle activity in humans 30 , suggesting that the integrity of spindles is essential to higher brain functions including cognition.…”

Different Simultaneous Sleep States in the Hippocampus and Neocortex

“…It is common for investigations of the role of sleep in learning to rely on EEG-based or behavioral sleep deprivation without knowledge of the sleep status of the learning-critical hippocampus. 47,48 Our data suggest that studies could be underestimating or over-estimating sleep states, occurring in a subcortical structure such as the hippocampus when such states are assigned using only cortical EEG and corporeal signals. For example, when air puffs were used to induce total sleep deprivation (REM, SWS, and TR) based solely on neocortical EEG and EMG, we found that sleep was totally eliminated from the neocortical signals, but that the hippocampus still entered non-REM sleep (SWS and TR) 10% to 30% of the time.…”

Fear memory consolidation in sleep requires protein kinase A

“…The animals were either kept awake (AW group) or allowed to sleep (SLEEP group) for 4 h. AW animals were kept awake by gently tapping on the chamber (1 tap every 15 min, on average), when they showed drowsiness. This method was chosen based on previous reports that gentle handling is very effective in keeping rodents awake (Meerlo et al 2001) while producing minimum stress, as determined by plasma corticosterone and adrenocorticotophic (ACTH) levels (Hagewoud et al 2010b;Gross et al 2015). Furthermore, sleep deprivation-induced stress has been reported to not be correlated to sleep deprivation-induced memory deficits (Hagewoud et al 2010b).…”