Exploring the neurocognitive basis of episodic recollection in autism

Abstract

Increasing evidence indicates that the subjective experience of recollection is diminished in autism spectrum disorder (ASD) compared to neurotypical individuals. The neurocognitive basis of this difference in how past events are re-experienced has been debated and various theoretical accounts have been proposed to date. Although each existing theory may capture particular features of memory in ASD, recent research questions whether any of these explanations are alone sufficient or indeed fully supported. This review first briefly considers the cognitive neuroscience of how episodic recollection operates in the neurotypical population, informing predictions about the encoding and retrieval mechanisms that might function atypically in ASD. We then review existing research on recollection in ASD, which has often not distinguished between different theoretical explanations. Recent evidence suggests a distinct difficulty engaging recollective retrieval processes, specifically the ability to consciously reconstruct and monitor a past experience, which is likely underpinned by altered functional interactions between neurocognitive systems rather than brain region-specific or process-specific dysfunction. This integrative approach serves to highlight how memory research in ASD may enhance our understanding of memory processes and networks in the typical brain. We make suggestions for future research that are important for further specifying the neurocognitive basis of episodic recollection in ASD and linking such difficulties to social developmental and educational outcomes.

Keywords: Autism; Episodic memory; Functional connectivity; Long-term memory; Recollection.

Fig. 1

Figure adapted from Cooper et al. (2017a). (a) Fixations made to two scenes studied during the memory encoding phase, illustrating the similarity in fixation patterns between the control and ASD groups. (b) While the number of encoding fixations did not differ between the groups, encoding fixations only predicted subsequent memory success (Hits and Correct Rejections) relative to false recognition (FAs) in the control group, and not in the ASD group. (c) Even when participants reported that they recollected a scene during retrieval, individuals with ASD did not reinstate encoding eye movements to the same degree as control participants did, which is illustrated in part (d)

Fig. 2

Figure adapted from Cooper et al. (2017b). (a) Participants with ASD and neurotypical controls exhibited similar hippocampal activity during successful recollection. (b and c) In contrast, widespread reductions in hippocampal functional connectivity (node in red) were observed in the ASD group relative to the control group during memory retrieval, particularly with regions of the fronto-parietal control network (nodes in yellow), but differences in connectivity strength were not observed during memory encoding. Effects are displayed at a threshold of p < .01 for visualization. Scales reflect t values