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Geoffrey Karl Aguirre, Omar Butt; The pattern of spontaneous visual cortex activity is not altered by callosotomy or extrastriate lesion. Journal of Vision 2014;14(10):1404. doi: https://doi.org/10.1167/14.10.1404.
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© ARVO (1962-2015); The Authors (2016-present)
Spontaneous "rest" fMRI signals have a spatial correlation structure in retinotopic visual cortex that resemble the radial organization of eccentricity and the hierarchical connectins of visual areas. The neural mechanism of this synchronized activity is unknown. We tested two hypotheses regarding the generation of resting state signals: First, does the corpus callosum mediate inter-hemispheric synchronization of fine-scale signals? Second, does eccentricity-selective feedback from high extrastriate cortical regions produce the gradient of correlation aligned with eccentricity? We obtained BOLD fMRI data at 3T while subjects rested with their eyes closed in darkness. 22 controls subjets contributed 8 minutes of data. Additionally, we studied a 54 year-old who underwent a total callosotomy 12 years prior for treatment of epilepsy (72 minutes), and a 48 year-old who underwent surgical resection of a right fusiform glioma 2 years prior (16 minutes). All data were transformed to cortical surface space (fsaverage sym). Volumetric digital lesion healing was conducted for the brain lesion patient prior to transformation to preserve cortical topology. We compared regional and fine-scale resting state patterns between the two patients and the mean and standard devation (SD) of the population of controls. Generally, we found that the patients were very similar to the control group. Measures of fine-scale correlation width and ampliude (Butt 2013, J Neurosci) were all within one SD of the control group mean. Regional, inter-hemispheric correlations were relatively reduced in both patients, but still within 1-2 SDs of the controls. Despite dramatic alterations of neuroanatomy, we found that our two patients had regional and fine-scale spontaneous activity within visual cortex that could not be distinguished from that of a control subject. These results place constraints upon the possible generative neural sources of resting state signals.
Meeting abstract presented at VSS 2014
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