Some developmental observations on the effects of prolonged deprivation of Low‐voltage Fast‐wave sleep in the deermouse, peromyscus maniculatus Bairdi

Abstract

Previous electrophysiological work with adult deermice (P. m. bairdi) (Mitler & Levine, 1970) indicated that: three states of arousal could be reliably distinguished: low-voltage, fast-wave sleep (LVF), high-voltage, slow-wave sleep (HVS), and waking (W); low-electromyograph (EMG) activity was concomitant with LVF; and time in LVF was radically reduced in mice perched above a shock-grid on a pedestal too small to permit total loss of muscle tonus. A preliminary aim of the present research was to gather electrophysiological data on juvenile deermice to construct some estimate of developmental sleep changes. Electrocorticograph (ECoG) and (EMG) records, from three 20-day-old mice while motionless with eyes closed, also reflected LVF, HVS, and W, but in proportions different from those reported by Mitler and Levine. Juvenile mice showed 1/3 more LVF than did adults. The main goal of this research was to explore the effects of long-term LVFdeprivation on juvenile and adult mice. Litters were selected at either 20 or 53 days of age. Littermates were assigned to one of four 14-day treatment conditions in an Age × Treatment design with 3 subjects per cell. The 1st treatment, LVF-deprivation, consisted of perching on a pedestal over a shock-grid. The remaining 3 conditions ran simulataneously with the former. Mice in the yoked control condition had approximately equal free movement volume as those mice restricted to the pedestal, and were 'yoked' to those animals with respect to shock. Mice in the sleep deprivation condition were confined to a treadmill in motion 19 of each 24 hr. Finally, mice in the isolated condition were caged alone. After treatment, animals were placed in activity recording cages for 21 days.Dependent variables included body weight before treatment, after treatment, and after procedure, brain weight, brain/body weight ratios, activity, and regularity of activity for the 21 days posttreatment. Major findings indicated that animals LVF-deprived from 20 to 34 days of age were more active than controls while animals LVF-deprived from 53 to 67 days of age were less active than controls. There were no interpretable differences among treatments in regularity of activity, body weight, or brain weight. Results were discussed in terms of input requirements for CNS development and/or maintenance. Directions for future research were suggested. (Meier & Berger, 1965). This latter state has also been termed " REMsleep" and "paradoxical sleep" (Dement, 1965;Jouvet, 1960). Both states appear in cyclic fashion (Aserinsky & Kleitman, 1953;Meier & Berger, 1965). KeywordsOf the 2 states, LVF has received more attention by far. One of the most striking properties of mammalian LVF is its diminution with age. The LVF/total-sleep ratio in humans drops from over 50% in infancy to less than 14% in old age (Roffwarg, Muzio, & Dement, 1966). Research with rhesus monkeys (Meier & Berger, 1965) also indicates a general developmental decline in LVF. Jouvet-Mounier (1968) and Jouvet-Mounier, Astic and Lacote, (1970) repo...