Directional specificity for head rotation in the pigeons posterior cerebellum.

Neurons in the posterior cerebellum, including the vestibulocerebellum, which respond to rotation in the plane of the horizontal semicircular canal exhibit considerably greater plane specificity than is known for primary afferents. This is shown by a response amplitude decline with tilt out of the canal plane which exceeds the decline predicted to a cosine function. Of 96 horizontal canal cells, 41 also responded to yaw movements about neck joints with only three of these cells exhibiting responses to roll movements as well. Other neurons responding to head rotation in roll very commonly responded to neck movements about the roll and/or pitch axes. Cells with converging vestibulo-cerevical input were found throughtout lobules VI to X, most of these cells being located in the uvula and only very few in the nodulus.