Brain areas involved in echolocation motion processing in blind echolocation experts

Abstract

People can echolocate their distal environment by making mouth-clicks and listening to the click-echoes. In previous work that used functional magnetic resonance imaging (fMRI) we have shown that the processing of echolocation motion increases activity in posterior/inferior temporal cortex (Thaler et al., 2011). In the current study we investigated, if brain areas that are sensitive to echolocation motion in blind echolocation experts correspond to visual motion area MT+. To this end we used fMRI to measure brain activity of two early blind echolocation experts while they listened to recordings of echolocation and auditory source sounds that could be either moving or stationary, and that could be located either to the left or to the right of the listener. A whole brain analysis revealed that echo motion and source motion activated different brain areas in posterior/inferior temporal cortex. Furthermore, the relative spatial arrangement of echo and source motion areas appeared to match the relative spatial arrangement of area MT+ and source motion areas that has been reported for sighted people (Saenz et al., 2008). Furthermore, we found that brain areas that were sensitive to echolocation motion showed a larger response to echo motion presented in contra-lateral space, a response pattern typical for visual motion processing in area MT+. In their entirety the data are consistent with the idea that brain areas that process echolocation motion in blind echolocation experts correspond to area MT+.