Abstract
In order to analyze inhibitory effect of the bulbar reticular formation upon the sudomotor activity, experiments were performed with 25 adult cats immobilized with Flaxedil. Response patterns of skin potential due to brain stimulation were classified into three types; facilitatory, inhibitory and mixed.
1. Inhibitory response was elicited from the bulbar ventromedial reticular formation. From region surrounding the inhibitory area, mixed response was evoked. Facilitatory response was elicited from the bulbar lateral reticular formation.
2. Inhibitory response due to bulbar stimulation became marked with increase in strength, pulse duration or frequency. The strength-duration curve for threshold of a 50% decrease in amplitude of the GSR was a rectangular hyperbola and chronaxie calculated from the vt-t curve was 0.3msec.
3. The stimulation of restricted area surrounding the inhibitory area, produced inhibitory response at frequencies above 150/sec. In this area, however, response frequently appeared in the form of facilitation at frequencies below 10/sec. At frequencies between 10 and 150/sec., mixed response was elicited.
4. Analysis of post-inhibitory rebound following bulbar stimulation, revealed that there exists an optimum duration of brain stimulation which causes a maximum of rebound: 5 seconds. It was also found that there exists a close parallelism between amplitude of rebound and degree of inhibition. Contribution of IPSP to initiation of post-inhibitory rebound was suggested.
