[Neural mechanisms of group I fibers of neck muscles (author's transl)].

Afferent projection of upper cervical dorsal roots C2 and C3 upon spinal cord and brain stem was investigated on cats using both histological and electrophysiological methods. 1. Degenerated terminals, stained by Fink-Heimer's methods, were found in Rexed's laminae III and IV, intermediate nucleus and ventral horn of the spinal cord and nucleus cuneatus and spinal trigeminal nucleus. 2. Monosynaptic reflex responses were obtained from motor nerves innervating dorsal neck muscles by stimulating the dorsal roots in some decerebrated cats. However, this reflex responses could be unable to elicite in the spinal preparation. 3. The neurons responding exclusively to the ventral rami located in cranial parts of the nucleus and those responding to dorsal rami located in the caudal region. Neurons responding to both rami were also found.