Fig. 1.

How do animals develop sensorimotor maps linking motoneurons and muscles? Initially, the mapping relations are unknown, metaphorically illustrated here by a bank of switches (neurons) connected in unknown ways to a cluster of light bulbs (muscles). Faced with this confusion, the guy at the switchboard would be wise to throw each switch one at a time and tally the lights that turn on. Analogously, animals may use discrete twitches during sleep to establish, refine, maintain, and repair sensorimotor circuits throughout the nervous system. From Blumberg et al. (2013). Twitching in sensorimotor development from sleeping rats to robots. Current Biology, 23, R532–R537.