• Kala P Nair, Raghava Jagadeesh Salaka, Bettadapura N Srikumar, Bindu M Kutty, and Shankaranarayana RaoByrathnahalli SBSDepartment of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India. Electronic address: bssrao.nimhans@gmail.com..
• Department of Neurophysiology, National Institute of Mental Health and Neuro Sciences, Bengaluru, India.
• Neuroscience. 2022 Jul 15; 495: 97-114.

AbstractSleep dysfunctions in epilepsy increase the burden of seizures and cognitive impairments. Seizures and certain anti-seizure drugs (ASDs) can affect sleep quality, leading to excessive daytime sleepiness and poor cognitive performance. Therefore, it is imperative to develop non-pharmacological strategies to curb epilepsy and related sleep dysfunction. Enriched environment (EE) has been demonstrated to ameliorate seizures and associated comorbidity in animal models of epilepsy. However, its effects on epilepsy-induced sleep dysfunctions and altered neural activity remain unexplored. To study the same, chronic epilepsy was induced in male Wistar rats and subjected to standard or enriched housing (6 h/day for 14 days), after which sleep/wake cycle, EEG spectral power and coherence during all vigilance states were analysed. Further, hippocampal parvalbumin-positive (PV+) interneurons were quantified to correlate the functional implications with the electrophysiological changes. Epileptic rats showed decreased rapid eye movement (REM) sleep, prolonged REM latency, and extended wake after sleep onset (WASO). Power spectrum analysis indicated an increase in delta and theta activity with a concomitant decrease in gamma activity during wake, an increase in prefrontal cortex (PFC)- Cornu ammonis (CA1) coherence, and a significant loss of hippocampal PV+ interneuron density. Exposure to EE restored REM sleep duration and latency without altering WASO in epileptic rats. EE also restored delta power during non-rapid eye movement (NREM) and theta, gamma power during wake, PFC-CA1 coherence, and PV+ interneurons density. These results further strengthen the role of EE's positive effects on brain plasticity and aid in developing non-pharmacological strategies to mitigate epilepsy-associated comorbidities.Copyright © 2022 IBRO. Published by Elsevier Ltd. All rights reserved.

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