Objective: The aim of this study is to investigate the circadian and homeostatic modulation of the multi-unit activity of dopamineric and striatal neuronal structures.

Background: Several neurological disorders associated with Basal Ganglia dysfunctioning, like Parkinson’s and Huntington’s diseases, are characterised by seriously debilitating sleep abnormalities. The involvement of Basal Ganglia in sleep modulation has been recently documented. However, the reciprocal modulation of Basal Ganglia activity by sleep-wake dependent processes is unknown.

Methods: We combined Electroencephalogram (EEG) recordings with electrical multi-unit activity (MUA) in different subdivisions of both Midbrain Dopaminergic structures [Substantia nigra lateral (SNL, n=6), Substantia nigra Medial (SNM, n=5), Ventral Tegmental area (VTA, n=6)] and striatal structures [Striatum Latero-dorsal (STR-LD, n=4), Striatum Medio-dorsal (STR-MD, n=4), Ventral striatum (STR-V, n=4)] under 12:12 light/dark (LD) and constant darkness (DD)conditions. We also investigated the effects of a 6h sleep deprivation on MUA in these areas.

Results: Both under LD and DD conditions, the MUA in the areas examined showed a vigilance state dependency with the highest firing rates during wakefulness and REM sleep compared to NREM sleep (p<0.001, t-test). Interestingly, striatal subdivisions displayed different sensitivities towards changes in homeostatic sleep pressure as evidenced by EEG Slow Wave Activity.

Conclusions:

Our results indicate that circadian and homeostatic processes influence the activity of midbrain dopaminergic and striatal structures. These influences may contribute to behavioural changes observed in neurological disorders related to dysfunctioning in the Basal Ganglia.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/circadian-and-homeostatic-modulation-of-multi-unit-activity-in-dopaminergic-and-striatal-structures/