Neural Correlates of Human Cognition in Real-World Environments

Abstract

According to embodied accounts of human cognition, the mind is at the interface of the body and the environment. For practical reasons, however, neuroscientific research on human cognition has mostly been confined to the laboratory until now. The emergence of portable brain and body imaging research methods offers an unprecedented opportunity to capture the expression of cognitive processes during active behaviours performed in real-world contexts. In the present thesis, electroencephalography (EEG) was used to investigate embodied aspects of human cognition in motion and in the real-world. This approach, however, presents new challenges in terms of signal processing because of the increased noise related to whole body movements. As the necessary signal processing tools were not well-established, the current work involved the development of new solutions to address the specific requirements of mobile EEG data before real-world brain recordings could be validly interpreted. In a series of Event Related Potential (ERP) experiments, real-world conditions were compared to traditional lab-based conditions. The neural marker of attention (P300 ERP) was recorded when participants performed an attentional task while walking through the university’s corridors versus standing in the lab. Differences in the classic P300 ERP effect show that attentional processes in the real-world are not the same as those recorded in the lab. Following up on this finding, the attenuation of the P300 effect under real-world conditions was shown to be driven by cognitive demands related to displacement through space rather than the act of walking itself. This is a demonstration, at a brain level, that when walking in the real-world, cognitive resources are reallocated to the processing of visual flow and vestibular information associated with displacement. The findings reflect the dynamic interplay between mind, body, and environment, providing innovative evidence strengthening the embodied framework of human cognition. The same dynamic interplay between body, environment and cognitive function is uniquely represented in real-world navigation. The literature on spatial navigation in humans, however, mainly involved navigating virtual reality environments often while lying on a scanner bed. Most of the evidence on the neural markers of spatial navigation comes from intracranially recorded brain oscillations in rodents. The innovation in this thesis was to investigate brain oscillations associated with cognitive function underlying real-world navigation in humans using surface electrodes. The present work demonstrates that human brain dynamics related to navigational cognitive processes can be recorded in active exploration of real-world environments. The key finding resulting from this novel approach is that real-world spatial navigation is associated with specific neural signatures underlying distinct cognitive functions. Frontal low-frequency oscillations were found to be associated with wayfinding, while parietal high-frequency oscillations were associated with spatial memory. Furthermore, these neural correlates were found to be dynamically modulated depending on the body’s contextual positioning within the environment. Therefore, these findings again provide evidence in support of the embodiment theory of cognition. The final study addressed the concern that findings might reflect walking speed variation. The existing animal literature has shown that low-frequency bands are modulated by walking speed. This study characterised the specific modulations in spectral power as a function of walking speed in humans. Critically the pattern showed no similarity to the spectral patterns found in relation to real-world spatial navigation, confirming the cognitive interpretation of this work. Taken together, these findings provide innovative real-world evidence supporting the theoretical embodiment framework. The neural correlates of attention, memory, and spatial navigation were found to be modulated by the dynamic experience of one’s environment. Beyond this work’s theoretical implications for cognitive sciences, the present findings offer new perspectives for real-world application.