In normal implanted cats, squirel monkeys and baboons, various types of localized rhythms can be identified in somatic area I and in the visual zone. Their relation to levels of attentiveness, alertness or drowsiness, and their possible correspondence to human EEG activities, wicket or mu rhythms and occipital alpha rhythms is considered. Subcortical recordings tend to show that these rhythms correspond to distinct thalamo-cortical systems, involving different thalamic nuclei.