Neural attractor dynamics in object recognition.

A widely held theory dating back to Donald Hebb posits neuronal attractor dynamics to underlie the retrieval of objects from long-term memory and the categorization of ambiguous stimuli, but empirical support for this notion had so far pointed more at self-sustained activity than at attractor dynamics per se. Complex perceptual effects modulating memory retrieval, including priming effects, are compatible with both attractor dynamics and alternative hypotheses, which seem to result in opposite predictions at the neuronal level. Recent recordings in monkeys indicate that attractor dynamics may indeed be observed, as it unfolds in time over a few hundred milliseconds, if neurons are probed in infero-temporal cortex during the categorization of ambiguous visual stimuli. Extending the analysis of such phenomena promises to take us beyond the perceptual periphery, where neuronal responses are still largely determined by sensory stimuli. Understanding the nature of transitions between attractor states opens the door to higher-level thought processes.