Hippocampal contributions to reading processes
TL;DR
The involvement of the left hippocampus and, in particular, of the hippocampal body during typical reading is revealed, confirming the need to incorporate subcortical regions into current language-network models.
Abstract
The cortical substrates of typical reading have been extensively investigated. However, the functional contributions of subcortical regions to reading remain poorly understood and are largely absent from current neuroanatomical models. In the present fMRI study, we analyzed three datasets to test whether specific hippocampal subregions (head, body, and tail) contribute to reading through distinct patterns of activation and functional connectivity. Results across all datasets revealed that reading was associated with left-lateralized hippocampal activation, with the hippocampal body typically more engaged than either the hippocampal head or tail. Regarding functional connectivity, the left hippocampal head and body showed a stronger coactivation with the ventral (as opposed to the dorsal) reading network in all datasets, suggesting a role in semantic (rather than phonological) processing. Altogether, our study reveals the involvement of the left hippocampus and, in particular, of the hippocampal body during typical reading, confirming the need to incorporate subcortical regions into current language-network models. Moreover, the connectivity of the left hippocampus to the ventral reading stream provides initial evidence suggesting that the hippocampus contributes to semantic reading processes.