The Complementary Brain (Abstract)

Abstract

How are our brains functionally organized to achieve adaptive behavior in a changing world? This talk will survey evidence supporting a computational paradigm that radically departs from the computer metaphor suggesting that brains are organized into independent modules. Evidence is reviewed that brains are organized into parallel processing streams with complementary properties. This perspective clarifies, for example, how parallel processing in the brain leads to visual percepts and object recognition, and how perceptual mechanisms differ from those of movement control. Multiple modeling studies predict how the neo-cortex is organized into parallel processing streams such that pairs of streams obey complementary computational rules (as when two puzzle pieces fit together). Hierarchical interactions within each stream and parallel interactions between streams create coherent behavioral representations that overcome the complementary deficiencies of each stream and support unitary conscious experiences. For example, visual boundaries and surfaces seem to obey complementary rules in the Interblob and Blob streams from area V1 to V4. They interact to generate visible representations of 3D surfaces in which partially occluded objects are mutually separated and completed. Visual boundaries and motion in the Interblob and Magnocellular cortical processing streams seem to obey complementary computational rules in cortical areas V2 and MT. They interactively form representations of object motion in depth. Predictive target tracking (e.g., targets moving relative to a stationary observer) and optic flow navigation (e.g., an observer moving relative to its world) seem to obey complementary computational rules in ventral and dorsal MST.