The K-complex in thalamic depth recordings.

K-complexes were recorded from the thalamus in a patient having stereotaxic surgery for intractable stump pain. Two insertions were performed, one in the lateral and the other in the medial thalamus. It was found that, (1) very prominent K-complex activity was present at the depth electrode with relatively meager representation of these forms at the scalp; (2) the trailing spindle component of the K-complex was well displayed on the scalp, but the sharp and slow components were not readily visible in the scalp recordings, suggesting a multiple system response; (3) insertion into the lateral thalamus revealed much K-complex activity in contrast to the relatively little amount found with the insertion into the medial thalamus. These findings support earlier hypotheses of a subcortical origin, and specifically thalamic participation, in the K-complex formations.