– Developing the sensorimotor system in our sleep –
During active (REM) sleep in mammals, skeletal muscles twitch throughout the body, causing jerky movements of limbs, whiskers, and eyes. These spontaneous, discrete movements are particularly prominent during the perinatal period, when active sleep predominates. As demonstrated in newborn rats, the triggering of a twitch is followed by a cascade of sensory feedback (reafference) through the sensorimotor system. Twitch-related activity also results in coherent oscillatory activity in such structures as sensorimotor cortex, hippocampus, and red nucleus. In addition, the production of twitches by brainstem motor structures gives rise to motor copies that flow to the cerebellum; within the cerebellum, computations are performed in which information about the production of a twitch is combined with information about the sensory consequences of a twitch to yield signals, conveyed to motor thalamus and motor cortex, that carry predictive information about the sensory consequences of self-generated movement. Finally, we are also studying sleeping human infants from birth through six months of age to assess similarities and differences in the expression of twitching and twitch-related neural activity. Although we see many parallels between infant humans and rats in the spatiotemporal organization of twitching during active sleep, we have also found—to our surprise—that humans, beginning around three months of age, exhibit increasing rates of twitching during quiet sleep; these twitches during quiet sleep are synchronized with cortical sleep spindles along the sensorimotor strip. All together, these findings highlight the many ways that sleep provides a critical context for the expression of organized activity in cortical and subcortical structures, ultimately producing a brain that is functionally integrated with its body.
Mark BLUMBERG – Department of Psychological & Brain Sciences, University of Iowa
Invited by Rosa COSSART
Zoom Metting – Monday, May 31th at 3 pm
ID meeting: 861 5562 0118