Resolving the Abstract-Concrete Paradox in the Angular Gyrus: A Multimethod Investigation

Despite its well-established role in memory-guided cognition, whether and how the angular gyrus (AG) contributes to semantic processing remains unresolved. Particularly, connectomic work links the AG to various forms of abstract mentation, yet neuroimaging studies paradoxically show greater AG engagement for concrete than abstract semantics. To address this inconsistency, here we present a multimethod investigation by integrating evidence from neurostimulation, neuroimaging, and experience sampling across five studies. Using the contrast between concrete and abstract semantics as a diagnostic test-case, we show that this ostensible contradiction reflects multiple interacting neurocognitive factors that jointly define AG functional repertoire. In Study 1, causal disruption of the AG disproportionately impaired abstract semantics and temporary retention of task information, demonstrating that the AG contributes to performance under abstract and memory-guided demands. In Study 2, apparent concreteness effect (higher AG activity for concrete semantics) was abolished after accounting for performance speed/accuracy, indicating that AG involvement is driven more by mental activities associated with low-demand states rather than concreteness per se. In Study 3, the AG showed enhanced functional coupling with regions of the semantic network, suggesting ongoing integration with the semantic network (despite lower activation for abstract words) rather than disengagement. In Study 4, experience sampling revealed that concrete semantics preferentially elicited mental imagery and automaticity, providing a phenomenological account of heightened AG engagement under low-demand conditions. In Study 5, we addressed methodological ambiguities in interpreting AG activation and deactivation, clarifying how baseline choices and task designs jointly determine the extent of its engagement. Together, these findings show that AG engagement is best understood along a continuum of memory-guided cognition, clarifying when this region supports abstract versus concrete semantics and why its activation can vary across semantic contexts. SignificanceThe contribution of the AG to semantic processing has long been debated, both regarding whether it is reliably engaged and how such engagement should be interpreted. By integrating evidence from multiple independent datasets using complementary methodologies, the present investigation moves beyond single-process accounts to identify multiple contributors that jointly define AG function. These factors align with contemporary connectomic research that situates the AG at the transmodal apex of a principal cortical gradient. Under this brain-connectomic framework, AG involvement is amplified as representations become abstract, information is buffered, operation becomes automatic, imagery is simulated, reliance on perception is reduced, shifting from perception-guided mode to memory-guided cognition. Together, these findings provide a principled framework for interpreting the elusive patterns of AG functionality.