Letter | Published:

Invariant visual representation by single neurons in the human brain

Nature volume 435, pages 11021107 (23 June 2005) | Download Citation



It takes a fraction of a second to recognize a person or an object even when seen under strikingly different conditions. How such a robust, high-level representation is achieved by neurons in the human brain is still unclear1,2,3,4,5,6. In monkeys, neurons in the upper stages of the ventral visual pathway respond to complex images such as faces and objects and show some degree of invariance to metric properties such as the stimulus size, position and viewing angle2,4,7,8,9,10,11,12. We have previously shown that neurons in the human medial temporal lobe (MTL) fire selectively to images of faces, animals, objects or scenes13,14. Here we report on a remarkable subset of MTL neurons that are selectively activated by strikingly different pictures of given individuals, landmarks or objects and in some cases even by letter strings with their names. These results suggest an invariant, sparse and explicit code, which might be important in the transformation of complex visual percepts into long-term and more abstract memories.

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We thank all patients for their participation; P. Sinha for drawing some faces; colleagues for providing pictures; I. Wainwright for administrative assistance; and E. Behnke, T. Fields, E. Ho, E. Isham, A. Kraskov, P. Steinmetz, I. Viskontas and C. Wilson for technical assistance. This work was supported by grants from the NINDS, NIMH, NSF, DARPA, the Office of Naval Research, the W.M. Keck Foundation Fund for Discovery in Basic Medical Research, a Whiteman fellowship (to G.K.), the Gordon Moore Foundation, the Sloan Foundation, and the Swartz Foundation for Computational Neuroscience.

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    • R. Quian Quiroga

    †Present address: Department of Engineering, University of Leicester, LE1 7RH, UK


  1. Computation and Neural Systems, California Institute of Technology, Pasadena, California 91125, USA

    • R. Quian Quiroga
    • , L. Reddy
    •  & C. Koch
  2. Division of Neurosurgery and Neuropsychiatric Institute, University of California, Los Angeles (UCLA), California 90095, USA

    • R. Quian Quiroga
    •  & I. Fried
  3. Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA

    • G. Kreiman
  4. Functional Neurosurgery Unit, Tel-Aviv Medical Center and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel

    • I. Fried


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Reprints and permissions information is available at npg.nature.com/reprintsandpermissions. The authors declare no competing financial interests.

Corresponding author

Correspondence to R. Quian Quiroga.

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    Supplementary Notes

    This contains Supplementary Methods and Legends to accompany Supplementary Figures S1-11.

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