TheJournalofNeuroscience,创新.PDFVIP

The Journal of Neuroscience, August 13, 2014 • 34(33):11067–11084 • 11067 Systems/Circuits Dynamic Target Match Signals in Perirhinal Cortex Can Be Explained by Instantaneous Computations That Act on Dynamic Input from Inferotemporal Cortex Marino Pagan and X Nicole C. Rust Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104 Finding sought objects requires the brain to combine visual and target signals to determine when a target is in view. To investigate how the brain implements these computations, we recorded neural responses in inferotemporal cortex (IT) and perirhinal cortex (PRH) as macaque monkeys performed a delayed-match-to-sample target search task. Our data suggest that visual and target signals were com- bined within or before IT in the ventral visual pathway and then passed onto PRH, where they were reformatted into a more explicit target matchsignalover 10–15ms.AccountingforthesedynamicsinPRHdidnotrequireproposingdynamiccomputationswithinPRHitself but, rather, could be attributed to instantaneous PRH computations performed upon an input representation from IT that changed with time. We found that the dynamics of the IT representation arose from two commonly observed features: individual IT neurons whose response preferences were not simply rescaled with time and variable response latencies across the population. Our results demonstrate that these types of time-varying responses have important consequences for downstream computation and suggest that dynamic repre- sentations can arise within a feedforward framework as a consequence of instantaneous computations performed upon time-varying inputs. Key words: dynamic; computation; population coding; object; target Introduction The computations required to create a target match signal can be Finding sought objects and switching between targets requires en