1. Neuroscience
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Using an achiasmic human visual system to quantify the relationship between the fMRI BOLD signal and neural response

  1. Pinglei Bao
  2. Christopher J Purington
  3. Bosco S Tjan  Is a corresponding author
  1. University of Southern California, United States
  2. University of California, Berkeley, United States
Research Article
  • Cited 9
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Cite this article as: eLife 2015;4:e09600 doi: 10.7554/eLife.09600


Achiasma in humans causes gross mis-wiring of the retinal-fugal projection, resulting in overlapped cortical representations of left and right visual hemifields. We show that in areas V1-V3 this overlap is due to two co-located but non-interacting populations of neurons, each with a receptive field serving only one hemifield. Importantly, the two populations share the same local vascular control, resulting in a unique organization useful for quantifying the relationship between neural and fMRI BOLD responses without direct measurement of neural activity. Specifically, we can non-invasively double local neural responses by stimulating both neuronal populations with identical stimuli presented symmetrically across the vertical meridian to both visual hemifields, versus one population by stimulating in one hemifield. Measurements from a series of such doubling experiments show that the amplitude of BOLD response is proportional to approximately 0.5 power of the underlying neural response. Reanalyzing published data shows that this inferred relationship is general.

Article and author information

Author details

  1. Pinglei Bao

    Neuroscience Graduate Program, University of Southern California, Los Angeles, United States
    Competing interests
    The authors declare that no competing interests exist.
  2. Christopher J Purington

    School of Optometry, University of California, Berkeley, Berkeley, CA, United States
    Competing interests
    The authors declare that no competing interests exist.
  3. Bosco S Tjan

    Psychology, University of Southern California, Los Angeles, CA, United States
    For correspondence
    Competing interests
    The authors declare that no competing interests exist.


Human subjects: The Institutional Review Board of the University of Southern California approved the experimental protocol, and each subject provided written informed consent.

Reviewing Editor

  1. Jody C Culham, University of Western Ontario, Canada

Publication history

  1. Received: July 23, 2015
  2. Accepted: November 26, 2015
  3. Accepted Manuscript published: November 27, 2015 (version 1)
  4. Version of Record published: February 14, 2016 (version 2)


© 2015, Bao et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.


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