Thalamic Grey Matter Volume Changes After Sleep Deprivation in Rats

The modern life style demands a prolonged wakefulness despite the mounting evidences that deficit in adequate amount and quality of sleep impairs the wellbeing including attention, executive functions, working memory and other general functioning of the body. The thalamus plays a key role in mediating sleep–wakefulness through its intrinsic as well as extrinsic network connection with brainstem and cortex through ascending reticular activating system. In the present study, we examined the effects of 24, 48 and 72 h sleep deprivation in three separate groups of male Wistar rats on the thalamic grey matter volume. The three groups of rats ( n = 18(6 × 3)) were sleep-deprived for three different durations, i.e. 24, 48 and 72 h using modified multiple platform method. Brain imaging was done using 7 T small animal MR scanner before and after sleep deprivation. From the acquired images, the total volume of the thalamus was calculated. The volume of the hippocampus was taken as reference. The grey matter volume of the thalamus showed a decreasing trend after sleep deprivation in all three groups of rats. Though the decrease in the thalamic volume was not statistically significant, the present study is the first animal MRI experiment to report the decrease in the thalamic grey matter volume after sleep deprivation which supports the similar findings in humans. The synaptic homeostatic hypothesis that cortical excitatory synapses should increase in size after wake and decrease after sleep is not evident in thalamus.