September 2005
Volume 5, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   September 2005
The effect of attention and contrast on the BOLD response in V1 and beyond
Author Affiliations
  • Xian Zhang
    Psychology Department, Columbia University, and Functional MRI Research Center, Columbia University
  • John Ferrera
    Clinical Neuropsychology [PhD program], CUNY Graduate Center, and Functional MRI Research Center, Columbia University
  • Donald C. Hood
    Psychology Department, Columbia University
  • Joy Hirsch
    Psychology Department, Columbia University, and Functional MRI Research Center, Columbia University
Journal of Vision September 2005, Vol.5, 681. doi:10.1167/5.8.681
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Xian Zhang, John Ferrera, Donald C. Hood, Joy Hirsch; The effect of attention and contrast on the BOLD response in V1 and beyond. Journal of Vision 2005;5(8):681. doi: 10.1167/5.8.681.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract

Purpose: To investigate the effects of attention on the response contrast function of the BOLD response of the visual cortex, the results of passive viewing were compared to that of a 2-back memory task, which diverted attention.

Methods: A randomly reversing, scaled dartboard display, typically used for multifocal VEP experiments, was presented at 6 contrasts ranging from 0 to 100% during whole brain functional imaging. A central fixation cross, which also served as the target of the task, was presented as a random sequence of red and green 0.5s flashes every 2s. The subjects viewed the display either passively or while performing a 2-back memory task. Thus, there were 12 (6 contrast levels X 2 viewing) conditions. Each of 4 runs contained 12 16s blocks separated with 20s rest periods. 8 subjects participated. The data were analyzed using a mixed effect analysis (FSL software). V1 was determined using standard retinotopic techniques (BrainVoyager).

Results: The response log contrast function of the BOLD activation at the visual cortex was approximately linear for both attention conditions. The BOLD signal from V1 was only slightly reduced under the 2-back condition. However, other brain regions including medial frontal gyrus, insula, higher visual cortex, and cuneus showed large differences between the two tasks. In particular an extensive negative BOLD response (NBR) was observed during the 2-back task. The NBR differed from the V1 positive response in two ways. First,it was not contrast dependent, i.e.the NBR was approximately the same for 0% and 100% contrast. Second, the NBR exhibited a different time course than the positive BOLD signal , ending slightly more abruptly.

Conclusion: Diverting visual attention while viewing a reversing dartboard display appears to exert a minimal affect on the contrast response function in V1. However, an extensive negative BOLD response was induced outside of V1 during the 2-back task suggesting a widely distributed task-dependent mechanism.

Zhang, X. Ferrera, J. Hood, D. C. Hirsch, J. (2005). The effect of attention and contrast on the BOLD response in V1 and beyond [Abstract]. Journal of Vision, 5(8):681, 681a, http://journalofvision.org/5/8/681/, doi:10.1167/5.8.681. [CrossRef]
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×