Table 2 Included studies on episodic long-term memory
Authors | NASD/NTD | ASD age | Diagnosis method Diagnosis criteria Diagnosis | Material Memory task | Neuroimaging method Memory phase | Memory accuracy | Main results (ASD relative to TD groups) Conclusion |
|---|---|---|---|---|---|---|---|
Chan et al. [86] | 21/21 | 10.27 ± 2.26 | DSM-IV Autistic disorder, PDD-NOS | Visuospatial: line drawings Object recognition task | EEG Recognition | Reduced | Greater antero-posterior theta connectivity in the left hemisphere in ASD, and in the right hemisphere in TD. Negative correlation between coherence and performance in ASD only Threshold of connectivity beyond which performance decreased |
Churches et al. [81] | 11/11 | 31.82 ± 6.88 | DSM-IV Asperger | Visuospatial: neutral faces Recognition | EEG Recognition | Reduced | Reduced amplitudes on the N170 potential for both target and non-target faces; reduced amplitude on the N250 potentials to target faces only The development of new face representation is impaired |
Cook et al. [92] | 12/19 | 13.18 ± 1.73 | ADI-R and/or ADOS DSM5 ASD | Visuospatial: object–scene pairs Rate the congruence | fMRI Encoding | Reduced object recognition Similar associative recognition | TD: encoding of subsequently recognized pairs associated with greater activation of the bilateral medial prefrontal cortex for intermediate relative to congruent pairs, and with greater activation of the left medial temporal lobe for congruent relative to intermediate pairs ASD: same level of activation regardless of the level of congruence; higher activations in bilateral, prevailing left medial prefrontal areas, for participant with greater behavioral flexibility Lack of modulation of encoding-related processes with the level of congruency |
Cooper et al. [90] | 24/24 | 30.3 ± 8.4 | DSM5 or ICD-10 ASD | Visuospatial: background, and objects Recognition | fMRI Encoding and recognition | Reduced | Encoding: similar levels of activity and connectivity among prefrontal, hippocampal and parietal areas Recognition: limited differences: reduced left prefrontal activity, and reduced hippocampal connectivity with the fronto-parietal areas Memory representations are processed similarly by the hippocampus; limited pre-retrieval search or post-retrieval monitoring |
Desaunay et al., [79] | 22/32 | 16.51 ± 3.56 | ADI-R and/or ADOS DSM5 and ICD-10 ASD | Visuospatial: picture pairs Associative recognition | EEG Recognition | Reduced | Reduced amplitude on the P2 and FN400 potentials: limited integration of low-level perceptual into high-level conceptual information, decrease in familiarity strength Spatial extension of the LPC: suggests additional recruitment of associative processes Effortful retrieval of associative information compensates for the lower familiarity strength |
Gaigg, et al. [89] | 13/12 | 35.6 ± 10.3 | ADOS DSM-IV ASD | Verbal: word triplets, semantically related or not Associative recognition | fMRI Encoding | Similar | Similar brain activations, including the left inferior frontal gyrus and the left hippocampus, with similar signal change with the degree of relational encoding Only limited signal change in prefrontal and posterior hippocampal regions, when contrasting the degree of awareness for subsequent retrieval Attenuated levels of recollection are related to anomalies in relational encoding processes |
Greimel et al., [82] | 13/13 | 15.9 ± 3.0 | ADI-R and ADOS DSM-IV and ICD-10 HFA, PDD-NOS, Asperger | Visuospatial: objects superimposed with faces or houses Recognition of the objects | fMRI Encoding | Similar | Encoding of subsequently recollected objects presented with a face: reduced activations within bilateral inferior and medial frontal gyri and the right intraparietal lobule Encoding of subsequently non-recollected objects presented with houses: increased activation of the dorsal-medial PFC Incidental encoding of faces in the ASD group is less automatic and less associated with social information |
Gunji et al. [80] | 8/9 | 10.8 ± 2.9 | DSM-IV HFA, Asperger | Visuospatial: self, familiar, unfamiliar faces Recognition of the subject’s own face and familiar faces | EEG Recognition | Similar | Shorter N170 latency No amplitude difference on the early posterior negativity between Self vs. Familiar and Familiar vs. Unfamiliar No amplitude difference on the P300 between familiar and unfamiliar faces Deficit of semantic encoding of faces |
Hogeveen et al. [91] | 47/60 | 18.4 ± 2.81 | ADOS-2 DSM5 ASD | Visuospatial: item-specific or relational encoding Item or associative recognition | fMRI Encoding | Similar (for item and associative recognition) | Increased hippocampal activity along with diminished connectivity between the medial temporal lobe and postero-medial brain regions Hippocampal hyper-recruitment suggests compensation for the decrease in regional connectivity to support the preservation of associative memory |
Lynn et al. [83] | 13/13 15/16 13/14 | 11.7 ± 1.2 15.3 ± 1.8 24.9 ± 4.9 | ADI and ADOS Autism | Visuospatial: faces and cars Recognition | fMRI Encoding and recognition | Reduced (for both faces and cars) | Encoding and recognition: face-specific underconnectivity between bilateral fusiform face areas and the medial PFC Recognition: both general (i.e., cars) and specific (i.e., faces) underconnectivity between the right fusiform face area and the visual cortex Diminished integration of information; abnormalities in perceptual systems also contribute to recognition deficits, especially with faces |
Massand et al. [87] | 22/14 | 25.72 ± 4.76 | ADI-R and/or ADOS DSM-IV ASD | Verbal: high- and low-frequency words Recognition | EEG Recognition | Similar | Parietal rather than anterior early FN400 old/new effect related to familiarity Similar parietal LPC potential related to recollection Preservation of the electrophysiological recollection process |
Massand & Bowler [88] | 15/18 | 38.89 ± 14.77 | ADOS DSM-IV Autism, Asperger | Visuospatial: line drawings of objects Recognition (line drawings) and recall (their color) | EEG Recognition and recall | Reduced recognition | Posterior and attenuated FN400 old/new effect related to familiarity, occurring in a large time-window (300-650 ms) Similar parietal LPC potential related to recollection Preservation of the electrophysiological recollection process |
Neumann et al. [78] | 7/7 | 20.9 ± 10.6 | ADI-R ICD-10 HFA “mnemonist savants” | Verbal: pseudowords Visuospatial: abstract shapes Recognition | MEG Recognition | Reduced (pseudowords) Similar (shapes) | Both stimuli: early right occipital activation (100-200 ms) in ASD only Shapes: bilateral old/new effect (200-500 ms) reflecting familiarity-based recognition, being more left hemispheric in controls Expertise with figural material; pseudowords were processed and recognized similarly to visual material |
Noonan et al. [85] | 10/10 | 23 ± 9.9 | ADI-R and ADOS DSM-IV HFA | Verbal: words read or heard Recognition (item and source) | fMRI Recognition | Reduced | Unexpected enhanced left fronto-parietal functional connectivity Atypical functional connectivity |
O’Hearn et al. [84] | 15/13 16/19 14/15 | 11.7 ± 1.17 15.39 ± 1.17 24.56 ± 4.87 | ADI and ADOS Autism | Visuospatial: faces and cars Recognition | fMRI Encoding and recognition | Reduced (for both faces and cars) | Similarity of fusiform face area activation increased from childhood to adolescence, then decreased from adolescence to adulthood Recognition performance was more related to the similarity score in the left fusiform face area Reduced specialization of the fusiform face area |