Opponent visuospatial coding as a fundamental organising principle of brain integration

An essential human behaviour is our ability to effectively integrate signals arising from external sensory information (e.g., visual input) with internal cognitive representations (e.g., memory). Such integration allows us to complete seemingly trivial everyday behaviours, such as recalling where you left your keys or imagining your partner's face. However, the mechanisms by which the brain achieves this integration are not fully understood. For example, evidence suggests that perceptual and memory responses might share neural resources in early visual cortex. But, whether this sharing of neural resources extends to other brain regions and different cognitive tasks that also engage externally, and internally orientated processes is less clear. Recent work from our group has shed light on this question by demonstrating the presence of an opponent visuospatial coding scheme in memory-related brain areas. This opponent visuospatial coding was driven by population receptive fields that either responded positively (+ve pRFs) or negatively (-ve pRFs) to a stimulus within their receptive field in a push-pull manner: That is, as activity in one went up, the activity of the other went down and vice-versa. Importantly, at present this opponent visuospatial coding scheme has only been shown to operate within a specific set of brain regions and during a single internally orientated task - cued memory recall. The current proposal aims to test whether opponent visuospatial coding represents a fundamental organising principle of the brain by quantifying the extent to which opponent visuospatial coding structures the brain’s responses during a broad range of externally orientated tasks (controlled and naturalistic visual perception, listening to naturalistic spoken narratives) and internally orientated tasks (cued recall, free recall, speech production and resting-state). We will ask whether opponent visuospatial coding structures the brain's responses across these internally and externally orientated cognitive tasks in both space (where in the brain) and time (when in time). We aim to capitalise on the success of recent precision-fMRI approaches (e.g., Natural Scenes Dataset, [NSD]) that emphasise fewer participants but large volumes of high-quality data. We intend to follow the NSD framework by making these data freely available. To achieve this, we will complete two large-scale projects: During Project 1, we will use cutting-edge functional magnetic resonance imaging (fMRI) techniques to densely sample opponent visuospatial coding in each participant and capture each participant’s responses during tasks that emphasise internal or external cognitive processes. Such an approach will allow us to quantify the strength of opponent visuospatial coding within each participant and the degree to which that coding scheme structures that participant’s responses within the brain (i.e., space). During Project 2, we will use electroencephalography (EEG) recordings during the same internally and externally orientated tasks and in the same participants to capture the temporal dynamics of the brain’s responses. We will then use state-of-the-art computational modelling techniques to quantify the extent to which opponent visuospatial coding structures the brain’s responses across different cognitive states in time. By adopting these complementary approaches this proposal has the potential to identify whether opponent visuospatial coding represents a large-scale fundamental organising principle of the human brain and answer central questions about how the brain integrates internal and external cognitive representations. These are critical issues in Psychology and Neuroscience and fit well within the BBSRC’s Advancing the frontiers of bioscience discovery – understanding the rules of life strategic priority.