Somatotopic organization in the rat thalamic reticular nucleus.

Mapping experiments were carried out to establish the somatotopic organization of the somatosensory part of the thalamic reticular nucleus (TR) of the rat. Different parts of the body were found to project somatotopically onto the S-TR. The rostral-to-caudal and the dorsal-to-ventral axes in the body parts were transformed into the ventral-to-dorsal and the caudal-to-rostral axes in the S-TR, respectively. The head and face occupied about two thirds of the S-TR, distributing in the ventral half and in the dorsocaudal part. Particularly a large area of the S-TR was devoted to the vibrissae, nose (rhinarium) and lip. The trunk was projected to a small area of the dorsal part. The projections of the hind- and forelimb were mainly in the dorsal part, the former being placed above the latter.