The organization of sleep and wakefulness after maternal separation in young rats

Abstract

Two-week-old infant rats were studied before and after 24 hr of maternal absence. This experience produced an increase in time spent awake, a reduction in time spent in paradoxical sleep (PS), and an increased frequency of state transitions with more frequent and shorter periods of both slow-wave sleep (SWS) AND PS. Body movements were increased and nonnutritive sucking decreased during PS after separation. Other aspects of sleep organization were relativly stable: the pattern of probability of direction of state transitions, the integration of the physiological and behavioral determinants of state, the pattern and amount of nonnutritive sucking, and the underlying PS cycle period. These findings, and the results of 2 control experiments, suggest that some aspects of the prolonged absence of the mother produce a shift in the infant's central neutral state regulation through processes yet to be understood.

An Automated System for Recording and Analysis of Sleep in Mice

“…1 The authors' discussion of the effects of maternal separation in their results is extremely disingenuous. They fail to compare their results with those from studies where the effects of maternal separation on sleep are actually measured 8,9 or controlled. 3 Indeed, a comparison of their data with other studies of neonatal sleep, including a continuous polysomnographic sleep study in neonatal rats by Juvancz 10 (not cited by the authors), clearly shows that their data best resembles those obtained from studies where the effects of maternal separation are not controlled (Table 1).…”

“…3 Indeed, a comparison of their data with other studies of neonatal sleep, including a continuous polysomnographic sleep study in neonatal rats by Juvancz 10 (not cited by the authors), clearly shows that their data best resembles those obtained from studies where the effects of maternal separation are not controlled (Table 1). Since maternal separation alters vigilance state amounts, fragments sleep and disrupts the normal cycling of vigilance states, 8,9 studies that fail to adequately control for maternal separation are less representative of normal neonatal sleep than those that do.…”

“…3 In a series of studies, Hofer definitively showed that neonatal sleep is profoundly affected by variables provided by the mother rat (dam) such as warmth and milk. 8,9 The stressful effects of maternal separation, a condition required for long-term sleep recording experiments, can be reduced by incorporating proper grooming and feeding protocols in an experimental design (discussed in). 3 Consequently, all studies of neonatal sleep in ratsespecially those that deals with subtle issues of state emergence-should include proper controls for maternal separation (as we did in our studies).…”

Physical stimulation reduces the body temperature of infant rats

“…For example, neonatal sleep-wake cycles (Hofer, 1976;Hofer & Shair, 1982), ornithine decarboxylase levels (Butler, Suskind, & Schanberg, 1968;Evoniuk, Kuhn, & Schanberg, 1979;Kuhn, Butler, & Schanberg, 1978), normal adrenocortical activity (Smotherman, 1983;Stanton & Levine, 1984), heart rate (Hofer, 1971(Hofer, ,1973Hofer & Winer, 1975), and blood pressure (Shear, Brunelli, & Hofer, 1983) are all dependent upon maternal stimulation experienced by pups during normal contact with the dam. Also, Barnett and Walker (1974) have reported that stroking pups with a brush, a procedure used to mimic maternal stimulation, produces a decrease in pup surface body temperature.…”

Sleep-Wake State Organization in Infant Rats with Episodic Respiratory Disturbance Following Sinoaortic Denervation

“…Subcutaneous electrodes were placed across the anterior and posterior lateral thorax for recording respiratory pattern by impedance pneumography. This method is fully described in previous publications (4,5). The pups were replaced with their mothers for 2 days prior to the experiment to allow adaptation to the electrodes.…”