Anatomical, neural, and computational constraints on sensory cross-modal plasticity following early blindness

项目总结/文摘

Project Summary/Abstract Early blindness results in dramatic neuroplasticity within the human brain; anatomical and functional organization is altered at almost every level, ranging from neurotransmitter balance to neural function. I plan to combine psychophysics, computational functional magnetic resonance imaging (fMRI), diffusion-weighted MR imaging (dMRI), and MR spectroscopy (MRS) to investigate the anatomical, neural, and computational constraints of plasticity following early blindness. This proposal is driven by the hypothesis that cortical plasticity resulting from early blindness may share many of the same underlying mechanisms as ‘neuronal recycling, whereby the development of novel cortical functions (such as reading in sighted individuals) relies on the ‘recycling’ of evolutionarily older circuits that originally evolved for different, but similar, functions. I plan to examine this idea in the context of cross-modal plasticity within the visual motion area hMT+. Area hMT+, which processes visual motion in sighted individuals, responds selectively to auditory motion in early blind individuals. In Aim 1, using a combination of dMRI and fMRI, I will examine if the cross-modal responses to auditory motion within hMT+ in early blind individuals co-localizes with pre-existing anatomical connectivity between hMT+ and the auditory motion area right planum temporale (rPT). In Aim 2, I will test the hypothesis that auditory motion processing in EB is influenced by the spatiotemporal tuning within hMT+, using a combination of psychophysics and fMRI. In Aim 2, I will also examine whether the recruitment of hMT+ for auditory motion processing in early blind individuals results in a loss of sensitivity to auditory motion in rPT. Finally, in Aim 3, using a combination of psychophysics and fMRI, I will see if auditory motion responses in hMT+ can be explained by a classic model of divisive normalization that has been extensively used to model hMT+ visual motion responses in sighted individuals. By including MRS GABA measurements, I will further test whether the lower signal to noise associated with auditory rather than visual motion input results in an adaptive reduction in suppression, mediated by lower GABA concentrations. The training will focus on computational fMRI, dMRI, and MRS, which will augment my background in characterizing diverse human perceptual experiences using psychophysics and modeling. My mentors at the University of Washington (Drs. Ione Fine, Ariel Rokem, and Scott Murray) will provide excellent training in all the techniques used in this proposal. The award will provide an important opportunity for me to uniquely position myself in the field as an independent researcher with a strong research program that investigates the neuroanatomical basis of plasticity following visual deprivation.