Neural rhythmicity, feature binding, and serotonin: A hypothesis

Natural selection favors animals that make successful predictive theories about the world. The first step in the formation of these theories is the construction of complex, multifeature percepts. This process requires resolution of the binding problem, possibly via rhythmic cortical oscillations, as suggested by von der Malsburg, Singer, Koch & Crick, and others. If the binding process were made rewarding, animals might enjoy theory-making and spontaneously become "smarter." I argue that the serotonergic raphe may have been used by evolution to link cortical binding with limbic reward centers and so serve as a neural substrate for the enjoyment of successful theory-making. I present evidence, from the study of such disorders as obsessive-compulsive disorder and autism and such drugs as d-lysergic acid diethylamide (LSD) a nd 3,4- methylenedioxymethamphetamine (MDMA), suggesting that rhythmicity, reward, and pattern recognition are causally linked. I also propose that the genus Homo has tied powerful symbol manipulation hardware ("language") to the binding/theory-making circuits, allowing the construction, rehearsal, and communication of sophisticated models of the world. I suggest that many interesting phenomena, such as music-induced euphoria, deja vu, and the so-called "temporal lobe personality" can be explained by the interactions between these systems.