In WP1, we re-analyzed data from a large intracranial EEG dataset on spatial learning (for previous
publications on this dataset, see Chen et al., Current Biology 2018; Kunz et al., Science Advances
2018; Chen et al., Science Advances 2020) and from an fMRI dataset of the same paradigm (Kunz
et al., Science 2015). Since these two datasets employed an identical task, they are particularly
well suited to address objective 1, i.e. the relationship of activities across different levels of brain
organization. These data also allow addressing objective 2, because they contribute to a better
understanding of the specific cognitive functions (here: navigational strategies) that are supported by
neural activity in the core areas supporting the distinct spatial navigation strategies. We also started
with the analysis of human single unit data that were recorded concurrently with the intracranial EEG
data in a subset of patients (n=10 patients with both microelectrodes and macroelectrodes in entorhinal
cortex and hippocampus).
In WP2, and in line with our objective #2, which was to unravel the cognitive function of grid
cell-like representations and complementary spatially specific representations in other brain regions,
we developed novel experimental paradigms of “conceptual navigation” and of visual exploration
of the “spaces” of natural scenes. These paradigms capitalize on the employment of deep neural
networks, which we recently described as promising models of different “representational formats”
in the brain (Heinen et al., Brain Struct Funct 2023). First, we developed a paradigm that requires
participants to focus on either perceptual or conceptual dimensions of a stimulus, and to employ the
“cognitive map” defined by these dimensions for similarity judgments. We tested whether memory
traces of individual stimuli were embedded into these maps, i.e. whether these maps influenced the
memorability of the stimuli. This can be considered a prerequisite for a cognitive relevance of these
maps. Finally, we conducted a 7T fMRI study in order to investigate the laminar distribution of grid
cell-like representations in entorhinal cortex and their interaction with hippocampal subregions and
layers. Data acquisition is completed, and the data are currently preprocessed for further analysis.
