Abstract
To pursue objects of interest moving slowly in space, smooth pursuit requires precise control of vergence angles and interacts with vestibulo-ocular reflex (VOR). The floccular region plays a crucial role in generating smooth pursuit and modifying rotational VOR, and contains vergence signals (Miles et al. 1980). To examine discharge characteristics of floccular Purkinje (P) cells further, we first examined simple spike activity of 112 P cells during smooth pursuit and vergence at 0.5Hz (±5°) in 3 Japanese macaques. The majority (63%) responded to both eye movements, 24% responded only during vergence, and 13% responded only during smooth pursuit. Activity of the majority of P cells was modulated in proportion to vergence eye velocity and position. We also examined P cell discharge during sinusoidal linear (fore/aft) translation at 0.3Hz (±10cm) while the target moved in space with the same amplitude and phase as the chair (LVOR cancellation) or remained stationary in space (LVOR x1). Most P cells did not respond during LVOR cancellation but responded during LVOR x1 and their responses were correlated with compensatory vergence eye velocity. Some of these P cells responded during rotational VOR cancellation in yaw or pitch plane as reported previously. These results indicate that the majority of floccular P cells carry both smooth pursuit and vergence eye movement signals but do not receive otolith inputs. [Jpn J Physiol 55 Suppl:S176 (2005)]
