Conditioned modification of locomotion in Hermissenda crassicornis: analysis of time-dependent associative and nonassociative components.

The contribution of associative and nonassociative factors to the conditioned modification of phototactic behavior in Hermissenda was examined after varying the number of conditioning trials and the time between training and testing. Five or 10 conditioning trials did not produce significant changes in phototactic behavior when tested immediately after training. Both 5 and 10 conditioning trials resulted in significant short-term nonassociative changes in behavior (resembling sensitization) when the time between training and testing was 15 min or longer. Following 50 conditioning trials (single session training), nonassociative effects made the major contribution to the change in behavior when the post-training test interval was 30 min. These nonassociative changes decremented during a 1-hr period following training. Significant associative effects were observed 45 min after 50 conditioning trials; however, significant associative effects were not observed when the same animals were tested 24 hr after training. With 3 days of training (multiple session training-150 trials), associative effects were found 30 min after training and nonassociative effects again showed a rapid decrement during the 1-hr period following the end of training. The associative effects observed soon after training were persistent during the retention period and showed significant effects 24 hr after training. These data indicate that (1) the behavioral effects found after single session training (5 and 10 trials) are nonassociative, and (2) these nonassociative effects do not increase significantly over the course of multiple session training.(ABSTRACT TRUNCATED AT 250 WORDS)