Representative behavioral and electrophysiological records in a head-fixed week-old rat. The figure depicts nuchal EMG (green), multiunit activity (MUA, black), and behavior (red; vertical ticks: myoclonic twitches; horizontal lines: wake-related movements). Note the increased nuchal muscle tone during wake and the preceding and following periods of muscle atonia; the EMG spikes that occur against a background of atonia are twitches. (Adapted from Tiriac et al. (2014). Self-generated movements with “unexpected” sensory consequences. Current Biology, 24, 2136–2141, with permission.)