Changes in the Human Brain Cortex in Response to Learning Click-Based Echolocation: A Virtual Navigation Paradigm

Abstract

Traditionally, sensory areas within the human brain are viewed as being tied to specific modalities. However, an emerging perspective suggests the brain may be organised in a flexible way, with sensory areas being driven by the task at hand. To investigate the functional organisation of the brain, we trained sighted people in echolocation related tasks and examined BOLD activity associated with the processing of echoic information before and after training. We then compared this activity to that observed in expert echolocators completing the same task. Despite sighted participants showing an improvement in echolocation ability, the brain regions recruited by expert echolocators and sighted participants appear to be somewhat different. When we isolated the processing of echoes, we found an increase in BOLD activation in the occipital cortex of expert echolocators, but not in sighted participants after training. Despite this, both groups displayed common activations within the primary auditory cortex. Similar results were also found when we compared the processing of all sounds to silence. When we investigated the processing of spatially coherent routes, compared to scrambled routes, we found activations within the occipital cortex of expert echolocators and sighted participants as a result of training. Our results suggest that the brain of expert echolocators may be organised in a flexible way, with sensory areas, such as the primary ‘visual’ cortex being recruited for the processing of auditory information. Furthermore, recruitment of the calcarine cortex in sighted people, after training, may hint at the possibility that the sighted brain is also organised in a flexible way, with areas typically devoted to vision, namely the occipital cortex, possibly processing spatial information conveyed by echoes.