Figure 1.

State dependent activity in cortical and thalamocortical networks. A. Slow wave sleep is associated with the generation of Up and Down states of the slow oscillation and spindle waves. The transition to waking is associated with an abolition of these network oscillations, the loss of the Down state of the slow oscillation, and the increased prevalence of rhythmic activity in the gamma frequency range. B. Recent recordings in head-fixed mice differ from the recordings in cats (A), and demonstrate the presence of slow oscillatory activity during quiet resting without movement. Walking on a cylinder results in a suppression of the slow rhythmic activity. Cessation of walking results in the return of the slow rhythmic activity. Recording was obtained from a putative fast spiking (parvalbumin positive) interneuron in the primary visual cortex. C. Schematic diagram of basic thalamocortical circuit for the generation of rhythmic activities. The slow oscillation is generated within the cortex as a relatively balanced recurrent interaction of excitatory and inhibitory neurons. Gamma frequency oscillations are also generated within the cortex, as an interaction of excitatory and inhibitory neurons. Spindle waves are generated during sleep in the thalamus as an interaction of thalamic reticular GABAergic neurons and thalamocortical relay cells. These rhythms interact with one and another, owing to the interconnected nature of the forebrain. Networks of inhibitory interneurons and intracortical connections are important for dynamic control of cortical state and oscillations[69-71]. A is from [5]; B is from [38].