Reduced Hippocampal Functional Connectivity During Episodic Memory Retrieval in Autism.

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.

Time perception and its relationship to memory in Autism Spectrum Conditions.

Timing is essential for the development of cognitive skills known to be impaired in Autism Spectrum Conditions (ASC), such as social cognition and episodic memory abilities. Despite the proposal that timing impairments may underpin core features of ASC, few studies have examined temporal processing in ASC and they have produced conflicting results. The present study first addressed discrepancies between previous experiments before testing the assumption that timing impairments may underpin key aspects of autism, by relating differences in temporal processing in the ASC group to memory abilities. Errors in duration reproduction in high functioning children with ASC were observed for the shortest and longest duration tested. While the former was due to attentional factors, the latter was due to deficient timing related to atypical episodic memory processing. These findings suggest that temporal processing abilities play a key role in the poor development of both social cognition and episodic memory abilities associated with ASC.

Eye movements reveal a dissociation between memory encoding and retrieval in adults with autism.

People with Autism Spectrum Disorder (ASD) exhibit subtle deficits in recollection, which have been proposed to arise from encoding impairments, though a direct link has yet to be demonstrated. In the current study, we used eye-tracking to obtain trial-specific measures of encoding (eye movement patterns) during incidental (natural viewing) and intentional (strategic) encoding conditions in adults with ASD and typical controls. Using this approach, we tested the degree to which differences in encoding might contribute to recollection impairments, or whether group differences in memory primarily emerge at retrieval. Following encoding of scenes, participants were asked to distinguish between old and similar lure scenes and provide 'remember'/'familiar' responses. Intentional encoding increased eye movements and subsequent recollection in both groups to a similar degree, but the ASD group were impaired overall at the memory task and used recollection less frequently. In controls, eye movements at encoding predicted subsequent correct responses and subsequent recollection on a trial-by-trial basis, as expected. In contrast, despite a similar pattern of eye movements during encoding in the two groups, eye movements did not predict trial-by-trial subsequent memory in ASD. Furthermore, recollection was associated with lower similarity between encoding- and retrieval-related eye movements in the ASD group compared to the control group. The eye-tracking results therefore provide novel evidence for a dissociation between encoding and recollection-based retrieval in ASD.

Reality Monitoring and Metamemory in Adults with Autism Spectrum Conditions.

Studies of reality monitoring (RM) often implicate medial prefrontal cortex (mPFC) in distinguishing internal and external information, a region linked to autism-related deficits in social and self-referential information processing, executive function, and memory. This study used two RM conditions (self-other; perceived-imagined) to investigate RM and metamemory in adults with autism. The autism group showed a deficit in RM, which did not differ across source conditions, and both groups exhibited a self-encoding benefit on recognition and source memory. Metamemory for perceived-imagined information, but not for self-other information, was significantly lower in the autism group. Therefore, reality monitoring and metamemory, sensitive to mPFC function, appear impaired in autism, highlighting a difficulty in remembering and monitoring internal and external details of past events.

Impaired recollection of visual scene details in adults with autism spectrum conditions.

Subtle memory deficits observed in autism spectrum conditions (ASC) have often been characterized as reflecting impaired recollection and it has been proposed that a relational binding deficit may underlie the recollection impairment. However, subjective recollection and relational binding have not been measured within the same task in ASC to date and it is unclear whether a relational binding deficit can provide a full account of recollection impairments in ASC. Relational memory has also not been compared with item memory when the demands of the 2 tasks are comparable. To assess recollection, relational memory, and item memory within a single task in ASC, 24 adults with ASC and 24 typically developed adults undertook a change detection memory task that assessed recollection of item-specific and spatial details. Participants studied rendered indoor and outdoor scenes and, in a subsequent recognition memory test, distinguished scenes that had not changed from those that had either undergone an item change (a different item exemplar) or a relational (spatial) change, which was followed by a subjective recollection judgment. The ASC group identified fewer item changes and spatial changes, to a similar degree, which was attributable to a specific reduction in recollection-based recognition relative to the control group. These findings provide evidence that recollection deficits in ASC may not be driven entirely by a relational binding deficit.

What is social about social perception research?

A growing consensus in social cognitive neuroscience holds that large portions of the primate visual brain are dedicated to the processing of social information, i.e., to those aspects of stimuli that are usually encountered in social interactions such as others' facial expressions, actions, and symbols. Yet, studies of social perception have mostly employed simple pictorial representations of conspecifics. These stimuli are social only in the restricted sense that they physically resemble objects with which the observer would typically interact. In an equally important sense, however, these stimuli might be regarded as "non-social": the observer knows that they are viewing pictures and might therefore not attribute current mental states to the stimuli or might do so in a qualitatively different way than in a real social interaction. Recent studies have demonstrated the importance of such higher-order conceptualization of the stimulus for social perceptual processing. Here, we assess the similarity between the various types of stimuli used in the laboratory and object classes encountered in real social interactions. We distinguish two different levels at which experimental stimuli can match social stimuli as encountered in everyday social settings: (1) the extent to which a stimulus' physical properties resemble those typically encountered in social interactions and (2) the higher-level conceptualization of the stimulus as indicating another person's mental states. We illustrate the significance of this distinction for social perception research and report new empirical evidence further highlighting the importance of mental state attribution for perceptual processing. Finally, we discuss the potential of this approach to inform studies of clinical conditions such as autism.