Abstract
In week-old rats, somatosensory input arises predominantly from external stimuli or from sensory feedback (reafference) associated with myoclonic twitches during active sleep. A previous study suggested that the brainstem motor structures that produce twitches also send motor copies (or corollary discharge, CD) to the cerebellum. We tested this possibility by recording from two precerebellar nuclei-the inferior olive (IO) and lateral reticular nucleus (LRN). In most IO and LRN neurons, twitch-related activity peaked sharply around twitch onset, consistent with CD. Next, we identified twitch-production areas in the midbrain that project independently to the IO and LRN. Finally, we blocked calcium-activated slow potassium (SK) channels in the IO to explain how broadly tuned brainstem motor signals can be transformed into precise CD signals. We conclude that the precerebellar nuclei convey a diversity of sleep-related neural activity to the developing cerebellum to enable processing of convergent input from CD and reafferent signals.
Highlights
IntroductionThe sensorimotor systems of diverse vertebrate and invertebrate species distinguish signals arising from self-generated movements (i.e., reafference) from those arising from other-generated movements (i.e., exafference; Cullen, 2004)
The sensorimotor systems of diverse vertebrate and invertebrate species distinguish signals arising from self-generated movements from those arising from other-generated movements
Recording sites were located within the dorsal accessory olive (DAO; n = 19 units across 12 pups) or the medial accessory olive (MAO) and the principal olive (PO; n = 18 units across eight pups; Figure 1C)
Summary
The sensorimotor systems of diverse vertebrate and invertebrate species distinguish signals arising from self-generated movements (i.e., reafference) from those arising from other-generated movements (i.e., exafference; Cullen, 2004) To make this distinction, motor structures generate copies of motor commands, referred to as corollary discharge (CD; Crapse and Sommer, 2008; Poulet and Hedwig, 2007). Discrete, jerky movements of skeletal muscles during active sleep (AS or REM sleep), a predominant behavioral state during early infancy (Jouvet-Mounier et al, 1969; Roffwarg et al, 1966) These spontaneous movements, called myoclonic twitches, are most abundant and conspicuous in developing mammals (Blumberg et al, 2013; Gramsbergen et al, 1970; Jouvet-Mounier et al, 1969; Roffwarg et al, 1966)
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