Evidence for autonomic-autonomic dissociation: an alternative to Dworkin and Dworkin (1990)

Dworkin and Dworkin (1990) reported that conditioned responses of the tibial nerve (a putative measure of skeletal motor activity) were uncorrelated with conditioned responses of the plantar vasculature during discriminative Pavlovian conditioning in the chronically paralyzed rat. On the basis of this finding, Dworkin and Dworkin concluded that the vasomotor response had not been mediated by skeletal motor processes. This commentary presents neuroanatomical, physiological, and behavioral evidence that suggests that sudomotor (sweat gland) and not skeletal motor efference might have been responsible for the classically conditioned tibial nerve response of Dworkin and Dworkin (1990). If this interpretation is correct, then Dworkin and Dworkin have documented an autonomic-autonomic dissociation, not a skeletal motor-autonomic dissociation. Response mechanisms in Pavlovian and instrumental autonomic conditioning are discussed.