Figure 2.

Characterizing state changes in behaving mice. A. Whole cell recordings from a pyramidal cell in the primary visual cortex of an awake mouse reveal that movement (walking) is associated with a depolarization of the membrane potential and a suppression of low frequency fluctuations. B. Simultaneous local field potential and multiple unit recordings from primary motor and somatosensory cortex of a mouse in the transition from stationary quiescence to movement (whisking). During quiescence, the cortex exhibits synchronized off periods reminiscent of Down states (yellow bars). These putative Down states may occur locally (e.g. asterisks). Whisking is associated with a suppression of these silent periods and the tonic activation of cortical circuits. C. Behavioral and cortical states are often viewed as exhibiting continuous changes delineated by abrupt transitions, although there may also exist multiple overlapping, yet discrete, states and substates. D. Characterization of behavioral state in rodents by principle component analysis of the activity of multiple brain areas reveals the major sleep-waking states seen behaviorally. Note that although the states exist within their own portions of state-space, they are not completely distinct and separate (left). Movement between states follows repeated paths (right). Abbreviations: AE: active exploration; IS: intermediate stage; REM: rapid eye movement sleep; SWS: slow wave sleep; QW: quiet wake; WT: whisker twitching. A from [9]; B unpublished data (EZ, DM); D from [23].