Eye dominance in the visual cortex using functional MRI at 1.5 T: an alternative method.
OBJECTIVE
To develop a functional MRI method for producing eye dominance histograms in humans at 1.5 Tesla (T).


METHODS
In the first set of experiments, 8 normal persons were tested. The eye dominance of each voxel within the person's visually activated primary visual cortex was determined with Student t statistics during a left eye versus right eye contrast. Eye dominance distribution was plotted, and the mean t statistic was used to describe the histogram asymmetry. In the second set of experiments, the effect of monocular optical blur and decreased luminance via filter was studied, and eye dominance distributions were similarly determined.


RESULTS
The eye dominance histogram in each of the 8 normals was approximately symmetric; the average mean t value was +0.13. All 4 subjects with the right eye blurred had histograms approximately symmetric or slightly shifted toward the left eye (average mean t = +0.56), and all 4 subjects with the right eye filtered had histograms dramatically shifted toward the left eye (average mean t = +2.22). The average mean t for the group with the right eye filtered was significantly different from that of the other 2 groups (P <.0001).


CONCLUSIONS
With noninvasive methods in normal persons, functional magnetic resonance imaging techniques at 1.5 T were able to characterize the distribution of eye dominance of voxels in primary visual cortex, based upon their t statistic in the left eye versus right eye contrast. The method is sensitive to filtering but relatively insensitive to visual blur. This approach may have a future use in the study of amblyopia in humans.
Liu
Grant T
GT
Children's Hospital of Philadelphia, Functional MRI Research Unit, and the University of Pennsylvania School of Medicine, Philadelphia 19104, USA. gliu@mail.med.upenn.edu
Miki
Atsushi
A
Goldsmith
Zachariah
Z
van Erp
Theo G M
TG
Francis
Ellie
E
Quinn
Graham E
GE
Modestino
Edward J
EJ
Bonhomme
Gabrielle R
GR
Haselgrove
John C
JC
D000293:Adolescent; D000328:Adult; D002648:Child; D023882:Dominance, Ocular / Q000502:physiology*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D014793:Visual Cortex / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology