Visceral signals reach visual cortex during slow wave sleep: study in monkeys

Area of Science:

• Neuroscience
• Gastroenterology
• Sleep Science

Background:

• Parkinson's disease models involve motor deficits and sleep disturbances.
• The connection between gastro-intestinal signals and brain activity during sleep is not fully understood.
• Primate models offer insights into complex physiological processes.

Purpose of the Study:

• To investigate the propagation of gastro-intestinal signals to the occipital cortex during the sleep-wake cycle in primates.
• To determine if visceral information transfer to the cortex occurs during sleep, particularly slow-wave sleep.
• To compare signal propagation in animals with varying degrees of motor impairment and sleep structure alterations.

Main Methods:

• Utilized a chronic MPTP model of parkinsonism in three monkeys with differing motor and sleep phenotypes.
• Implanted screw electrodes over the occipital cortex for sleep level evaluation and cortical evoked response recording.
• Administered intraperitoneal electrical stimulation via implanted gut electrodes during slow-wave sleep and wakefulness.

Main Results:

• Cortical evoked responses to visceral stimulation were observed during sleep in monkeys with normal sleep patterns (M1 and M2).
• No complete sleep cycles were observed in one severely motor-affected monkey (M3).
• Visceral information transfer to the cerebral cortex during slow-wave sleep was confirmed in primates with normal sleep.

Conclusions:

• Visceral signals are transmitted to the cerebral cortex during slow-wave sleep in primates with normal sleep patterns.
• This pathway remains functional even in the context of parkinsonism models, though sleep architecture may be affected.
• The study highlights a conserved mechanism for interoception during sleep across different physiological states.