Sequencing thought into speech: Hippocampal functions in linguistic linearization

The hippocampus has traditionally been understood as a memory system central to episodic representation, spatial navigation, and relational binding. Recent findings, however, suggest that its functions may extend beyond memory to the organization of sequential information. This raises the possibility that hippocampal mechanisms contribute to linguistic processes that require ordered expression, including the linearization of hierarchical syntactic structures. Linearization, defined as the mapping of parallel and recursive syntactic configurations onto a temporally constrained sequence of words, constitutes a fundamental problem for language production, yet its neurocognitive implementation remains insufficiently explained. Here, we advance the hypothesis that hippocampal sequence coding may provide one component of the neural substrate for this process. We review converging evidence from neuroimaging, patient studies, and developmental research that is consistent with hippocampal–prefrontal involvement during narrative construction, anaphora resolution, and temporal reference, as well as reports of disrupted discourse following hippocampal damage. We propose that these observations motivate testing whether hippocampal mechanisms help organize components of event representation into temporally structured relations within and across sentences. Building on proposals that sequence organization is relevant at both levels, we hypothesize that hippocampal indexing may interact with syntactic phases: syntactic phases define structurally bounded derivational domains, while hippocampal mechanisms may help relate event components and successive linguistic states across time. On this view, linearization may depend in part on a cross-modular interface between syntax and memory, with the hippocampus treated as a candidate contributor rather than as a dedicated linguistic linearizer.