August 2009
Volume 9, Issue 8
Free
Vision Sciences Society Annual Meeting Abstract  |   August 2009
The mapping of spatial frequency across amblyopic visual cortex
Author Affiliations
  • Robert Hess
    Dept. Ophthalmology, McGill University, Montreal, Canada
  • Benjamin Thompson
    Dept. Ophthalmology, McGill University, Montreal, Canada, and Dept. Optometry, University of Auckland, New Zealand
  • Xingfeng Li
    McGill University, Montreal, QC, Canada
  • Bruce Hansen
    Dept. Ophthalmology, McGill University, Montreal, Canada, and Dept. Psychology, Colgate University, NY, USA
Journal of Vision August 2009, Vol.9, 1056. doi:10.1167/9.8.1056
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      Robert Hess, Benjamin Thompson, Xingfeng Li, Bruce Hansen; The mapping of spatial frequency across amblyopic visual cortex. Journal of Vision 2009;9(8):1056. doi: 10.1167/9.8.1056.

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Abstract

Aims: Human amblyopes exhibit spatial frequency-specific behavioural deficits and we sought to understand how spatial frequency is represented in the amblyopic cortex and what aspects of processing might be disrupted.

Methods: MR images were acquired on a 1.5T Siemens scanner using a TR of 3sec. We used a phase-encoded design with a sinusoidal checkerboard stimulus (8Hz; 80% contrast; 20° field) that cycled from high to low spatial frequency (0.5–6c/d) and vice versa. Here we compare the phase responses as a function of stimulus spatial frequency.

Results: Following on from the approach of Sasaki et al, (2001 Nat. Acad Sci USA, 98, 2077) in normals, we found a similar mapping of spatial frequency across the amblyopic cortex, going from higher spatial frequencies more centrally, to lower spatial frequencies more peripherally. However, while there is a similar relationship between preferred spatial frequency for the amblyopic and normal eye, the spatial frequency map is less regular for the amblyopic input, reflecting the fact that fewer voxels exhibit a clear spatial frequency preference.

Conclusions: Spatial frequency is mapped in a qualitatively similar way for the normal and fellow amblyopic eye, although voxels exhibit less spatial frequency preference for the amblyopic eye input. This can be modeled as a broader spatial frequency tuning of individual cortical cells receiving input from the amblyopic eye.

Hess, R. Thompson, B. Li, X. Hansen, B. (2009). The mapping of spatial frequency across amblyopic visual cortex [Abstract]. Journal of Vision, 9(8):1056, 1056a, http://journalofvision.org/9/8/1056/, doi:10.1167/9.8.1056. [CrossRef]
Footnotes
 CIHR grant to RFH (#MOP-53346).
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