Operant Behavior in Model Systems

In contrast to the long-held assumption that the organization of behavior is best characterized as the perception of a sensory stimulus followed by appropriate response (i.e., “sensorimotor hypothesis”), recent converging evidence from multiple systems and fields of study instead suggests that both ancestral and extant general brain function is best described in operant terms. Rather than specifyng precise behaviors, sensory information - if at all present - interacts with ongoing neural activity to instruct the organism which type of spontaneous, exploratory behavior to generate. Evaluating the ensuing reafferent feedback modifies the nervous system such that ongoing neural activity patterns become biased towards activity that has generated increased appetitive and decreased aversive feedback in the past. The neurobiological mechanisms underlying both the exploratory, spontaneous behaviors as well as those underlying the modifications caused by the feedback are becoming increasingly understood, even on a molecular level. It is straightforward to hypothesize that the constant interaction between ongoing neural activity and the incoming sensory stream allows the organism to balance behavioral flexibility with efficiency to accomplish adaptive behavioral choice in an often unpredictably changing environment.