Further evidence for changes in the responsiveness of somatosensory neurons in arthritic rats: a study of the posterior intralaminar region of the thalamus.

In 21 arthritic rats, responses of 128 somatosensory neurons located in the intralaminar region of the thalamus were studied. This study reveals a profound change in the responses of intralaminar neurons in such rats, as compared with those observed in normal animals. Most of the activated neurons (98/120) were driven by moderate mechanical stimulation applied to the joints, while only few neurons (7/120) were exclusively driven by intense mechanical stimuli such as pinch. In addition numerous activated neurons were located in the ascending branch of the CL where in normal rat, few somatosensory 'noxious' neurons have been recorded.