Parametric information about eye movements is sent to the ears

Abstract

Eye movements alter the relationship between the visual and auditory spatial scenes. Signals related to eye movements affect neural pathways from the ear through auditory cortex and beyond, but how these signals contribute to computing the locations of sounds with respect to the visual scene is poorly understood. Here, we evaluated the information contained in eye movement-related eardrum oscillations (EMREOs), pressure changes recorded in the ear canal that occur in conjunction with simultaneous eye movements. We show that EMREOs contain parametric information about horizontal and vertical eye displacement as well as initial/final eye position with respect to the head. The parametric information in the horizontal and vertical directions can be modelled as combining linearly, allowing accurate prediction of the EMREOs associated with oblique (diagonal) eye movements. Target location can also be inferred from the EMREO signals recorded during eye movements to those targets. We hypothesize that the (currently unknown) mechanism underlying EMREOs could impose a two-dimensional eye-movement related transfer function on any incoming sound, permitting subsequent processing stages to compute the positions of sounds in relation to the visual scene. Significance StatementWhen the eyes move, the alignment between the visual and auditory scenes changes. We are not perceptually aware of these shifts -- which indicates that the brain must incorporate accurate information about eye movements into auditory and visual processing. Here we show that the small sounds generated within the ear by the brain contain accurate information about contemporaneous eye movements in the spatial domain: the direction and amplitude of the eye movements could be inferred from these small sounds. The underlying mechanism(s) likely involve(s) the ears various motor structures, and could facilitate the translation of incoming auditory signals into a frame of reference anchored to the direction of the eyes and hence the visual scene.