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Fang Jiang, Elizabeth Huber, Jessica Thomas, G. Christopher Stecker, Geoffrey Boynton, Ione Fine; Frequency-tuned auditory motion responses within hMT+ as a result of early blindness. Journal of Vision 2015;15(12):128. doi: https://doi.org/10.1167/15.12.128.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: Several fMRI studies have found directionally tuned responses to auditory motion in hMT+ in blind and sight recovery subjects (e.g. Jiang et al. 2013). Here we examined whether these auditory motion responses are tuned to frequency using sight recovery subject MM, who re-acquired vision during adulthood after becoming blind at age three. We previously showed that his hMT+ shows cross-modal responses to auditory motion, but can nonetheless be identified accurately using a visual motion localizer (Saenz et al. 2012). Methods: Data were collected on MM and 3 sighted controls. The auditory stimulus was band pass noise, with 7 center frequencies (125-3952 Hz). Each frequency band was presented for 2s and frequencies were presented in either ascending, descending, or semi-random order across scans. Auditory motion was simulated (using ITD and Doppler) as pairs of 1s bursts travelling at 30 m/sec from left to right or vice versa along the fronto-parallel plane. Subjects either listened passively or performed a one-back task in which they reported the repetition of a frequency (3 repeats/scan). The frequency tuning of each voxel was estimated as a Gaussian in log frequency space using population receptive field (pRF) modeling (Thomas et al., 2014). Results: Reliable tonotopic maps were found in primary auditory cortex in both MM and sighted controls for all conditions. No tonotopic responses were found within hMT+ in sighted controls for any condition. In MM we found robust frequency-tuned responses within both left and right hMT+ for the moving stimulus with the one-back task. However, hMT+ frequency-tuned responses were attenuated in MM when the stimulus was either stationary or there was no task, resembling responses seen in anophthalmic subjects by Watkins et al. (2013). Thus, MM’s auditory responses in hMT are tuned for frequency as well as motion, and are modulated by attention.
Meeting abstract presented at VSS 2015
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