Simultaneous recording of cortical and thalamic EEG and single neuron activity in the cat association system during...

Simultaneous recording of the EEG and single unit activity in cortex and thalamus shows that during spindles the cortical and thalamic EEGs within a given thalamocortical sector are highly correlated, but that the firing of only a fraction of cortical and thalamic neurons shows a close mutual correlation or exhibits a close relationship to the cortical and thalamic EEGs. Thus, only a fraction of thalamic and cortical neurons is involved in generating spindles. The synchronized activity of these neurons, even if some of it is subliminal for action potential discharge, suffices to produce a recordable EEG signal.