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Stefania S. Moro, Krista R. Kelly, Larissa McKetton, Jennifer K.E. Steeves; Asymmetrical medial geniculate body volume in people with one eye . Journal of Vision 2014;14(10):1133. doi: 10.1167/14.10.1133.
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Introduction. We have previously shown that people who have lost one eye early in life have enhanced sound localization (Hoover et al., 2011) and lack visual dominance (Moro & Steeves, 2011) compared to binocular and eye-patched viewing controls. People with one eye integrate auditory and visual information optimally, similar to controls, despite taking longer to localize unimodal visual stimuli (Moro, Harris & Steeves, 2013). Structurally, people with one eye have decreased lateral geniculate nuclei volume (LGN; thalamic visual relay station). However, this decrease is less severe in the LGN contralateral to the remaining eye, indicating altered structural development (Kelly, et al., 2013). The medial geniculate body (MGB; thalamic auditory relay station) plays a central role in auditory processing with both efferent and afferent tracts to primary auditory cortex (Schönwiesner, et al., 2007). Given the existing audiovisual processing differences and LGN changes in people with one eye, we investigated whether structural MGB changes are also present. Methods. MGB volume of adults who had undergone early unilateral eye enucleation was compared to binocularly intact controls. A series of 40 high-resolution proton density-weighted images were acquired with a 3T MRI scanner. Each series of scans were co-registered and averaged. Raters manually identified and traced MGB regions of interest in each participant. Results. People with one eye had a significant increase in MGB volume in the left compared to the right hemisphere independent of eye of enucleation. Controls did not exhibit this asymmetry. Conclusions. The volume asymmetry in the MGB in people with one eye may represent increased interaction between the left MGB and primary auditory cortex. This interaction could contribute to increased auditory attention, auditory spatial processing and other left hemisphere-dominant processing, including language. This asymmetry may reflect compensation for the loss of one half of visual inputs early in life.
Meeting abstract presented at VSS 2014
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