The Wake Promoting Role of the Mediodorsal Thalamic Nuclei in Rat

Mediodorsal thalamic nucleus (MD) is a higher order thalamic nucleus and plays an important role in memory, olfaction, cognitive functions and sleep pathology. However, its role in sleep–wake regulation needs elucidation. In the present study, we investigated the involvement of MD in the regulation of sleep wakefulness by studying the c-fos expression after normal sleep and sleep deprivation in rats. Total sleep deprivation was carried out using gentle handling. c-fos expression was quantified using immunofluorescence. There was significant increase in the expression of c-fos in MD after 6 h than 3 h of sleep deprivation compared to animals that slept naturally. The results of the present study suggest the involvement of the MD in the wake regulatory circuitry. It may play a crucial role in the integration of cognitive functions in the subcortical arousal networks before its specific projection to the prefrontal cortex.