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J Neurophysiol. 2015 Sep;114(3):1725-33. doi: 10.1152/jn.00567.2015. Epub 2015 Jul 15.

Neurochemical changes in the pericalcarine cortex in congenital blindness attributable to bilateral anophthalmia.

Author information

1
Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom;
2
Department of Psychology, University of Washington, Seattle, Washington;
3
Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom; Department of Experimental Psychology, University of Oxford, Oxford, United Kingdom.
4
Functional MRI of the Brain Centre, Nuffield Department of Clinical Neurosciences, University of Oxford, John Radcliffe Hospital, Oxford, United Kingdom; holly.bridge@ndcn.ox.ac.uk.

Abstract

Congenital blindness leads to large-scale functional and structural reorganization in the occipital cortex, but relatively little is known about the neurochemical changes underlying this cross-modal plasticity. To investigate the effect of complete and early visual deafferentation on the concentration of metabolites in the pericalcarine cortex, (1)H magnetic resonance spectroscopy was performed in 14 sighted subjects and 5 subjects with bilateral anophthalmia, a condition in which both eyes fail to develop. In the pericalcarine cortex, where primary visual cortex is normally located, the proportion of gray matter was significantly greater, and levels of choline, glutamate, glutamine, myo-inositol, and total creatine were elevated in anophthalmic relative to sighted subjects. Anophthalmia had no effect on the structure or neurochemistry of a sensorimotor cortex control region. More gray matter, combined with high levels of choline and myo-inositol, resembles the profile of the cortex at birth and suggests that the lack of visual input from the eyes might have delayed or arrested the maturation of this cortical region. High levels of choline and glutamate/glutamine are consistent with enhanced excitatory circuits in the anophthalmic occipital cortex, which could reflect a shift toward enhanced plasticity or sensitivity that could in turn mediate or unmask cross-modal responses. Finally, it is possible that the change in function of the occipital cortex results in biochemical profiles that resemble those of auditory, language, or somatosensory cortex.

KEYWORDS:

anophthalmia; blindness; choline; magnetic resonance spectroscopy; visual cortex

PMID:
26180125
PMCID:
PMC4571771
DOI:
10.1152/jn.00567.2015
[Indexed for MEDLINE]
Free PMC Article

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