The occipital place area is recruited for echo-acoustically guided navigation in blind human echolocators

Abstract

In the investigation of the brain areas involved in human spatial navigation, the traditional focus has been on visually guided navigation in sighted people. Consequently, it is unclear whether involved areas also support navigational abilities in other modalities. We explored this possibility by testing whether the occipital place area (OPA) – a region associated with visual boundary-based navigation in sighted people – has a similar role in echo-acoustically guided navigation in blind human echolocators. We used fMRI to measure brain activity in six blind echolocation experts (EEs; 5 males, 1 female), twelve blind controls (BCs; 6 males, 6 females), and fourteen sighted controls (SCs; 8 males, 6 females) as they listened to pre-recorded echolocation sounds that conveyed either a route taken through one of three maze environments, a scrambled (i.e. spatiotemporally incoherent) control sound, or a no-echo control sound. We found significantly greater activity in the OPA of EEs, but not the control groups, when they listened to the coherent route sounds relative to the scrambled sounds. This provides evidence that the OPA of the human navigation brain network is not strictly tied to the visual modality but can be recruited for non-visual navigation. We also found that EEs, but not BCs or SCs, recruited early visual cortex for processing of echo-acoustic information. This is consistent with the recent notion that the human brain is organised flexibly by task rather than by specific modalities.