Mobile EEG for investigating the role of the hippocampus in actively navigating humans

COEX 

The hippocampus is commonly associated with processing of allocentric spatial information tested in stationary setups, yet its interaction with physical locomotion in humans requires further investigation.

We implemented human scale virtual Morris Water Maze in desktop and mobile VR and analysed the EEG dynamics in individuals with right medial temporal lesions. Behaviourally (Iggena et al., 2023), the lesioned group showed greater improvement in navigation performance than controls when they had access to multisensory input from physical movement. The EEG power dynamics corroborates our interpretation of the behavioural findings that patients’ strategy relies on continuous integration of body-based information and its absence in desktop VR leads to exertion of greater cognitive effort in the group. Their strategy was reflected in the motion capture data indicating that patients preferred to replicate the previously walked trajectories and higher theta activity in the middle of stationary trials. On the other hand, the relationship between the oscillatory EEG dynamics and performance in controls implies that their performance in mobile VR depends on landmark-based planning at the beginning of a trial. Analysis of motion and EEG data revealed an increase in head angular velocity and the EEG theta power in the control group at the onset of mobile trials.

In summary, the mobile EEG data support our previous findings that patients compensate for attenuated hippocampal input using body-based instead of landmark-based navigation strategy. The results highlight the strength of MoBI in providing the full picture of brain-behavioral dynamics underlying naturalistic navigation which is not as readily accessible using stationary neuroimaging setups alone.