Nucleus reticularis thalami participates in sleep spindles, not in beta rhythms concomitant with attention in cat

In the awake cat, characteristic electrocortical synchronized oscillations (beta rhythms) can develop on the parietal cortex in specific behavioural situations such as during attentive fixation of a target. These activities differ from other synchronized rhythms which accompany slow sleep ("spindles") and are more widespread. It is shown here through single unit recording from the thalamic nucleus reticularis (RET), that the latter structure participates in spindles (as already postulated by other authors), but not in the beta rhythms which seem to depend on a more restricted thalamic focus in the posterior thalamic nucleus. These data thus support the idea that RET plays a role in slow-wave sleep but not in the cognitive operations involved in focussing attention.