Plane-specific Purkinje cell responses to vertical head rotations in the cat cerebellar nodulus and uvula.

We recorded simple spike (SS) and complex spike (CS) firing of Purkinje cell in the cerebellar nodulus and uvula of awake, head-restrained cats during sinusoidal vertical rotation of the head in four stimulus planes (pitch, roll, and two vertical canal planes). Two SS response types (position- and velocity-types) with response phases close to those of head position and velocity, respectively, were recognized. Optimal response planes and directions for SS and CS of each cell were estimated from the response amplitudes in the four stimulus planes by fitting with a sinusoidal function. The principal findings are as follows: (1) two rostrocaudally oriented functional zones of Purkinje cells can be distinguished; (2) the medially located parasagittal band is active during rotation in the pitch plane; (3) the laterally located band is active during rotation in the roll plane. These two zones are the same as previously reported zones in the cerebellar flocculus active during head rotation in the canal planes in the point that both cerebellar sagittal zones are plane-specific functional zones, suggesting that the anatomical sagittal zones serve as functional plane-specific zones at least in the vestibulocerebellum.