Abstract
In foraging situation, starving animals that possess sophisticated appendages exhibit dexterous manipulative behavior whose goal is to accomplish feeding. We aimed to understand neurophysiological mechanisms underlying goal-directed manipulative behavior that is based on their internal motivation for satiation, and hence adopted American lobster Homarus americanus as an experimental animal. The lobster has a pair of asymmetrical claws as the first thoracic appendages, one of which is developed as crusher claw. The crusher is utilized for gripping clamshell in their ecological foraging context. We developed reward operant conditioning systems for training the animals to grip a bar for food, and demonstrated that the frequency of gripping behavior can be controlled by the learning system in both free-moving and semi-restrained conditions. We also showed that the behavior can be induced by light stimuli as discriminative cues. Finally, we quantitatively characterized goal-directed gripping behavior in the lobster at the level of motor output by applying chronic electromyographic analysis. The series of our studies would be regarded as pioneering works for purveying a basis of neurophysiological investigation of goal-directed manipulative behavior in micro-brain animals.
