Successful animals tend to make efficient decisions in their daily activities in terms of effort spent, risk taken and benefit gained. In contrast, poor decisions affecting fitness are characteristic of anxiety, depression and many forms of mental illness that contribute to behavioral dysfunction. A grasp of the neural bases of decision is therefore essential to any unifying framework that models the organization of normal and abnormal behavior by the brain. Critical to the neural bases of decision is a description of how the nervous system integrates sensation, internal state and learning. A simple neural network model has been derived for cost-benefit decision-making in foraging from studies of behavior and nervous system in the simple predatory sea-slug, Pleurobranchaea. Within the context of the model, the feeding motor network is usefully conceived as a "goal-directed neural network" whose state of excitation is regulated by sensation, nutritional state and learning. This quality confers a role as a central, computational element for the cost-benefit algorithm that organizes expression of behavior. Rationale and experimental plans are outlined to elucidate how appetant stimulus properties, satiated state and food-avoidance learning act through the feeding motor network to influence decision in the motor network mediating both orienting and avoidance turns. Specifically, investigations will be aimed at explaining the neural bases for switching between orienting and avoidance turns, how this switch is determined by sensation, appetite and learning, and how avoidance decision may suppress feeding behavior. Studies will be carried out with conventional electrophysiological recording methods on well-tested physiological preparations. Results will have broad integrative significance to understanding how animals make successful behavioral decisions that balance perception of available resources and risk against their own needs, and will provide a simple model for approaching the neural circuitry for similar value-based decision-making in more complex animals. Undergraduate students, including minority members, are involved in these laboratory research activities. Research related materials from this lab, including videos, photographs and software, are disseminated for public information on the neural basis bases of behavior in sea slugs on a website written for accessibility by undergraduates and laypersons.
