Mesial temporal lobe and memory function in autism spectrum disorder: An exploration of volumetric findings

Abstract

Studies have shown that individuals with autism spectrum disorder (ASD) tend to perform significantly below typical developing individuals on standardized measures of memory, even when not significantly different on measures of IQ. The current study sought to examine within ASD whether anatomical correlates of memory performance differed between those with average-to-above-average IQ (AIQ Group) compared to those with low average to borderline ability (LIQ group) as well as in relations to typically-developing comparisons (TDC). Using automated volumetric analyses, we examined regional volume of classic memory areas including the hippocampus, parahippocampal gyrus, entorhinal cortex, and amygdala in an all-male sample AIQ (n = 38) and LIQ (n = 18) individuals with ASD along with 30 typically-developing comparisons (TDC). Memory performance was assessed using the Test of Memory and Learning (TOMAL) compared among the groups and then correlated with regional brain volumes. Analyses revealed group differences on almost all facets of memory and learning as assessed by the various subtests of the TOMAL. The three groups did not differ on any ROI memory-related brain volumes. However, significant size-memory function interactions were observed. Negative correlations were found between the volume of the amygdala and composite, verbal, and delayed memory indices for the LIQ ASD group indicating larger volume related to poorer performance. Implications for general memory functioning and dysfunctional neural connectivity in ASD are discussed.

Auditory attention in autism spectrum disorder: An exploration of volumetric magnetic resonance imaging findings

“…For example, negative findings can inform new ways of interpreting brain behavior relationships. Children with poor memory performance on paper and pencil tasks were thought to also have related brain atrophy until disproven and published in the literature (Trontel et al, 2015). Therefore, it is imperative that studies demonstrating methodological rigor remain accessible to the public.…”

“…The Test of Memory and Learning (TOMAL, Reynolds & Bigler, 1994) is a standardized clinical measure of memory that includes digit and letter span tasks. Examination of memory function between ASD and TDC (see Southwick et al, 2011; Trontel et al, 2015) demonstrated differences in memory systematically relating to differences in intellectual functioning. As a group, children with ASD are more likely to have lower intellectual scores when compared to TDC children (Charman et al, 2011; Mouga et al 2016), making it challenging to match on IQ.…”

Annual Research Review: Understudied populations within the autism spectrum – current trends and future directions in neuroimaging research

“…First, regions often implicated in ASD pathology more broadly (e.g. Ecker, Bookheimer, & Murphy, ; Stanfield et al., ) emerge in samples that include ASD + ID, with disruptions reported in frontal (Hazlett, Poe, Gerig, Smith, & Piven, ; Nordahl et al., ; Pardini et al., ; Riva et al., , ), striatal (Billeci et al., ; Riva et al., ), temporal (Boddaert et al., ; Hazlett et al., ; Piven, Arndt, Bailey, & Andreasen, ; Spencer et al., ), and cerebellar (Boddaert et al., ; Cascio et al., ; Jeong, Chugani, Behen, Tiwari, & Chugani, ; Riva et al., , ) regions (although for negative cerebellar results in ASD + ID, see Hashimoto, Murakawa, Miyazaki, Tayama, & Kuroda, ; Manes et al., ; Scott, Schumann, Goodlin‐Jones, & Amaral, ; Zeegers et al., ), as well as in the corpus callosum (Billeci et al., ; Egaas, Courchesne, & Saitoh, ; Haas et al., ; Manes et al., ; Spencer et al., ) and the amygdala–hippocampal complex (Dager et al., ; Schumann et al., ; Trontel et al., ; although see for a negative result; Zeegers et al., ). Second, it appears that the grey matter (GM) volumes and the WM structure are impacted in ASD + ID relative to TD controls, but clear patterns regarding the directionality and localization of these effects are difficult to ascertain in such a diverse literature.…”

Exploring the neurocognitive basis of episodic recollection in autism

“…Neuroimaging studies of memory in ASD have also provided limited evidence to date of specific hippocampal dysfunction. Interestingly, a recent study that investigated the link between memory and hippocampal structure in ASD found no evidence of differences in hippocampal volume between individuals with ASD and neurotypical controls and no correlation between hippocampal volume and memory function (Trontel et al, 2015 ). Moreover, fMRI studies to date have observed minimal evidence for differences in hippocampal activity during memory encoding in ASD (Cooper et al, 2017b ; Gaigg et al, 2015 ; Solomon et al, 2015 ), thus questioning the link between altered hippocampal relational encoding mechanisms and subsequent recollection in this population.…”