Effects of lesion of pontomedullary reticular formation on visually triggered vertical and oblique head orienting movements in alert cats.

The role of the nucleus reticularis pontis caudalis (NRPC) and the nucleus reticularis gigantocellularis (NRG) in control of vertical and oblique head orienting movements was investigated in alert cats by lesion of these nuclei with kainic acid. Cats were trained to orient the head vertically or obliquely to various targets. Following unilateral lesion of these nuclei, vertical orienting could be performed correctly with a slight decrease in velocity, while oblique orienting tended to exhibit zigzag course because of severe impairment of horizontal orienting. The horizontal and vertical components became coordinated in the course of experiments due to a significant decrease in vertical component velocity, resulting in smooth oblique trajectories. Results suggest that horizontal and vertical components of head orienting are controlled separately, but impairment of horizontal component causes adaptive change of vertical component velocity in oblique orienting.