The role of the hippocampus in working memory and word reading: Novel neural correlates of reading among youth living in the context of economic disadvantage.

Abstract

A left-lateralized cortical reading circuit underlies successful reading and fails to engage in individuals with reading problems. Studies identifying this circuit included youth from economically advantaged backgrounds and focused on cortical, not subcortical, structures. However, among youth with low scores on reading tests who are living in the context of economic disadvantage, this brain network is actively engaged during reading, despite persistent reading problems. This finding suggests that other brain circuits may underlie reading in these youth. A hippocampal circuit is one likely candidate, as it has recently been shown to support domain-general processes like working memory (WM) that are also associated with reading. Given age-related increases in hippocampal volume, WM, and reading, and known associations between WM and reading, we hypothesized that hippocampal volume would be associated with reading via WM processes. Using a cross-sectional developmental design, we explored this in middle childhood (average age at MRI scan ∼10; N = 50) and adolescence (average age at MRI scan ∼17; N = 175). Results suggest that the hippocampus is a critical contributor to word reading in adolescents living in economically disadvantaged contexts, and that this operates through working memory processes. Such findings point to new targets for reading intervention in adolescents.