Responses of worms to light as a function of intertrial interval and ganglion removal.

Abstract

Unconditioned responses of earthworms, Lumbricus terrestris, to light were found to be a complex function of time between test trials and ablation of supra and subpharyngeal ganglia. Normal worms made more URs [unconditioned responses] to light with an 88-sec. ITI [intertrial intervals] than with a 6-sec. ITI; more than 90% of URs were withdrawal (negative) responses; adaptation as measured by increased latencies occurred across 60 test trials. Ablation of supra, sub, or both neural ganglia led to decreased URs only for worms tested with 88-sec. ITI; more than 50% of URs were approach (positive) responses. Results are related to effects of ITI on conditioning and theory of ganglion control of response to light.