Impaired Spatial Hearing in Amblyopia: Evidence for Calibration of Auditory Maps by Retinocollicular Input in Humans

Abstract

PURPOSE. Evidence from animals and blind humans suggests that early visual experience influences the developmental calibration of auditory localization. Hypothesizing that unilateral amblyopia may involve cross-modal deficits in spatial hearing, we measured the precision and accuracy of sound localization in humans with amblyopia. METHODS. All participants passed a standard hearing test. Experiment 1 measured sound localization precision for click stimuli in 10 adults with amblyopia and 10 controls using a minimum audible angle (MAA) task. Experiment 2 measured sound localization error (i.e., accuracy) for click train stimuli in 14 adults with amblyopia and 16 controls using an absolute sound localization task. RESULTS. In Experiment 1, the MAA (mean 6 SEM) was significantly greater in the amblyopia group compared with controls (2.75 6 0.308 vs. 1.69 6 0.098, P ¼ 0.006). In Experiment 2, the overall sound localization error was significantly greater in the amblyopia group compared with controls (P ¼ 0.047). The amblyopia group also showed significantly greater sound localization error in the auditory hemispace ipsilateral to the amblyopic eye (P ¼ 0.036). At a location within this auditory hemispace, the magnitude of sound localization error correlated significantly with deficits in stereo acuity (P ¼ 0.036). CONCLUSIONS. The precision and accuracy of sound localization are impaired in unilateral amblyopia. The asymmetric pattern of sound localization error suggests that amblyopic vision may interfere with the development of spatial hearing via the retinocollicular pathway.

Intramodal cortical plastic changes after moderate visual impairment in human amblyopia

“…A few studies have investigated multisensory processing after visual sensory deprivation (see also Richards et al., 2019b for a review; Röder and Kekunnaya, 2021 for a review). Animal studies have shown that whereas the number of multisensory neurons in cats that were raised in complete darkness does not differ from sighted control animals, the response properties of those neurons differed between dark-reared and sighted control cats ( Wallace et al., 2004 ).…”