High-capacity, one-shot visual recognition memory challenges theories of learning and neural coding because it requires rapid, robust, and durable representations. Most studies have focused on the hippocampus and other higher areas. However, behavioral evidence demonstrating links between image properties and memorability and revealing image specificity of visual memory suggests an important role for mid-level visual cortex.
We tested the hypothesis that area V4 contains signals critical for recognition memory in two male rhesus macaques. Our task increased difficulty, allowing comparisons of neuronal population responses on correct and error trials. We observed signatures of several proposed memory mechanisms including magnitude coding, repetition suppression, sparse coding, and population response consistency, but only sparse coding and population response consistency predicted behavior.
Familiar images also evoked faster dynamics, consistent with pattern completion. These findings demonstrate that fast, high-capacity memory is supported by neural codes in mid-level sensory cortex independent of stimulus features per se, highlighting its role in distributed memory networks. We are grateful to Kursti Eaves for providing training and recording assistance, and to Ramanujan Srinath for his contribution to the linear decoding analysis.
We would also like to thank Douglas Ruff, Wilma Bainbridge, and Joel Voss for their help in improving the manuscript. This work is supported by the Simons Foundation (Simons Collaboration on the Global Brain award 542961SPI) and the National Institutes of Health (awards R01EY022930, R01EY034723, RF1NS121913, and 5T90DA059109-03). Department of Neurobiology, University of Chicago, Chicago, IL, USA Grace F.
DiRisio, Cheng Xue & Marlene R. Cohen Neuroscience Institute, University of Chicago, Chicago, IL, USA Correspondence to Cheng Xue or Marlene R. The authors declare no competing interests.
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