Age-related disorders of sleep and motor control in the rat models of functionally distinct cholinergic neuropathology.

We studied the impact of aging during sleep in the rat models of Alzheimer's (AD) and Parkinson's (PD) disease cholinergic neuropathology to determine the possible different and earlier onset of age-related sleep disorder during the neurodegenerative diseases vs. healthy aging. We used the bilateral nucleus basalis (NB) and pedunculopontine tegmental nucleus (PPT) lesioned rats as the in vivo models of functionally distinct cholinergic neuropathology, and we followed the impact of aging on sleep architecture, the electroencephalographic (EEG) microstructure and motor control across sleep/wake states. Our results have shown for the first time that the earliest signs of aging during distinct cholinergic neuropathology were expressed through a different and topographically specific EEG microstructure during rapid eye movement sleep (REM). EEG delta amplitude attenuation within the sensorimotor cortex (SMCx) during REM was the earliest sign of aging in the NB lesion. EEG sigma amplitude augmentation within the motor cortex (MCx) during REM was the earliest sign of aging in the PPT lesion. In addition, aging was differently expressed through the SMCx drive alterations, but it was commonly expressed through the MCx drive alterations during all sleep/wake states. Our study provided evidence of distinct REM sleep disorders and sleep state related cortical drives as the signs of aging onset during functionally distinct cholinergic neuropathologies (NB lesion vs. PPT lesion).