Exploring Information Flow from Posteromedial Cortex during Visuospatial Working Memory: A Magnetoencephalography Study

Abstract

The posteromedial cortex (PMC) is a major hub of the brain's default mode network, and is implicated in a broad range of internally driven cognitions, including visuospatial working memory. However, its precise contribution to these cognitive processes remains unclear. Using MEG, we measured PMC activity in healthy human participants (young adults of both sexes) while they performed a visuospatial working memory task. Multivariate pattern classification analyses revealed stimulus-related information during encoding and retrieval in a set of a priori defined cortical ROIs, including prefrontal, occipital, and ventrotemporal cortices, in addition to PMC. We measured the extent to which this stimulus information was exchanged between areas in an information flow analysis, measuring Granger-causal relationships between areas over time. Consistent with the visual nature of the task, information from occipital cortex shaped other regions across most epochs. However, the PMC shaped object representations in occipital and prefrontal cortices during visuospatial working memory, influencing occipital cortex during retrieval and PFC across all task epochs. Our findings are consistent with a proposed role for the PMC in the representation of internal content, including remembered information, and in the comparison of external stimuli with remembered material.

Recurrent connectivity supports higher-level visual and semantic object representations in the brain

“…While this kind of approach has been used in a number of studies to evaluate if there is shared information between regions over time (e.g. 29 , 40 , 41 ), the RCA approach we employ here goes one step further by specifying the precise nature of that shared information 17 , 32 —namely, is connectivity helping shape visual or semantic representations.…”

Recurrent connectivity supports higher-level visual and semantic object representations in the brain

“…While this kind of approach has been used in a number of studies to evaluate if there is shared information between regions over time (e.g. Goddard et al, 2022; Kietzmann et al, 2019; Lyu et al, 2019), the RCA approach we employ here goes one step further by specifying the precise nature of that shared information (Karimi-Rouzbahani et al, 2021, 2022) – namely, is connectivity helping shape visual or semantic representations.…”