Reduced Hippocampal Functional Connectivity During Episodic Memory Retrieval in Autism

Abstract

Increasing recent research has sought to understand the recollection impairments experienced by individuals with autism spectrum disorder (ASD). Here, we tested whether these memory deficits reflect a reduction in the probability of retrieval success or in the precision of memory representations. We also used functional magnetic resonance imaging (fMRI) to study the neural mechanisms underlying memory encoding and retrieval in ASD, focusing particularly on the functional connectivity of core episodic memory networks. Adults with ASD and typical control participants completed a memory task that involved studying visual displays and subsequently using a continuous dial to recreate their appearance. The ASD group exhibited reduced retrieval success, but there was no evidence of a difference in retrieval precision. fMRI data revealed similar patterns of brain activity and functional connectivity during memory encoding in the 2 groups, though encoding-related lateral frontal activity predicted subsequent retrieval success only in the control group. During memory retrieval, the ASD group exhibited attenuated lateral frontal activity and substantially reduced hippocampal connectivity, particularly between hippocampus and regions of the fronto-parietal control network. These findings demonstrate notable differences in brain function during episodic memory retrieval in ASD and highlight the importance of functional connectivity to understanding recollection-related retrieval deficits in this population.

Progression from feature-specific brain activity to hippocampal binding during episodic encoding

“…The absence of hippocampal correlates of subsequent memory early on in encoding is particularly interesting in light of inconsistency in the literature. Although hippocampal encoding effects have often been reported (Spaniol et al, 2009;Kim, 2011), many individual studies have not found them (e.g., Sommer et al, 2005;Haskins et al, 2008;Cooper et al, 2017;Tibon et al, 2019). Although variability in hippocampal encoding effects might be attributed to differences in memory strength and trial selection (Henson, 2005), the current results suggest an additional possible explanation--namely, that such inconsistencies might be related to the duration of the encoding event used in fMRI analyses.…”

A Physiological Marker of Recognition Memory in Adults with Autism Spectrum Disorder? ‐ The Pupil Old/New Effect

“…With less information to base their judgments on, this could be related to difficulties distinguishing old and new items and increased false alarm (FA) rates [e.g., Gardiner, Bowler, & Grice, ]. Qualitative differences are also supported by recent neurophysiological evidence suggesting that both episodic and semantic memory are associated with atypical patterns of neural activity in ASD [Gaigg et al, ; Massand, Bowler, Mottron, Hosein, & Jemel, ; Massand & Bowler, ; Cooper et al, ]. These studies, however, also show that covert physiological indices exist that can index the memory atypicalities that characterize the disorder.…”

Genetic mutations in Ca2+ signaling alter dendrite morphology and social approach in juvenile mice

“…These brain regions were chosen because both have been implicated in NDDs, such as autism. Changes in connectivity have been reported in the hippocampus and the somatosensory cortex of patients with autism vs neurotypical controls . Changes in hippocampal volume, and reduced branching of CA1 hippocampal neurons have also been reported in brains of autism vs neurotypical controls .…”