Specialization of anterior and posterior hippocampal functional connectivity differs in autism.

Structural and functional differences in the hippocampus have been related to the episodic memory and social impairments observed in autism spectrum disorder (ASD). In neurotypical individuals, hippocampal–cortical functional connectivity systematically varies between anterior and posterior hippocampus, with changes observed during typical development. It remains unknown whether this specialization of anterior–posterior hippocampal connectivity is disrupted in ASD, and whether age‐related differences in this specialization exist in ASD. We examined connectivity of the anterior and posterior hippocampus in an ASD (N = 139) and non‐autistic comparison group (N = 133) aged 5–21 using resting‐state functional magnetic resonance imaging (MRI) data from the Healthy Brain Network (HBN). Consistent with previous results, we observed lower connectivity between the whole hippocampus and medial prefrontal cortex in ASD. Moreover, preferential connectivity of the posterior relative to the anterior hippocampus for memory‐sensitive regions in posterior parietal cortex was reduced in ASD, demonstrating a weaker anterior–posterior specialization of hippocampal–cortical connectivity. Finally, connectivity between the posterior hippocampus and precuneus negatively correlated with age in the ASD group but remained stable in the comparison group, suggesting an altered developmental specialization. Together, these differences in hippocampal–cortical connectivity may help us understand the neurobiological basis of the memory and social impairments found in ASD. Lay Summary: The brain's hippocampus is an important structure for memory, learning, and social interaction. Research has shown differences in the structure and function of the hippocampus in autism. We investigated the anterior–posterior specialization of the hippocampus; whereby the front and back portions of the hippocampus display unique patterns of coordinated activity with the rest of the brain. This specialization matures during child development and is related to memory performance. Based on previous work, we hypothesized that hippocampal specialization would differ in those diagnosed with autism. Using magnetic resonance imaging, we measured the coordinated activity of the hippocampus with the rest of the brain in autistic and non‐autistic children and young adults. We identified several brain regions displaying different hippocampal specialization between autistic and non‐autistic participants. Many of these regions are known to be involved in memory processes. Interestingly, only the autistic group showed age‐related differences in specialization. This suggests that distinct developmental patterns of hippocampal specialization exist in autistic and non‐autistic children. These findings help us understand how the hippocampus functions differently in autism and may give insight into differences in memory and social behavior. [ABSTRACT FROM AUTHOR]