External organization cue facilitates memory retrieval of children with autistic spectrum disorder: An EEG synchronization study

Objective. Some studies found that autistic spectrum disorder (ASD) associated memory deficits were related to frontal lobe dysfunctions, e.g., ineffective organization strategy for memory. Yet, the memory profile of ASD remains inconclusive. The present study aims to examine the memory profile of ASD children based on the information processing model and its association with their organization strategies adopted, and to explore the effect of ‘voiced’ (with explicit instruction) and ‘unvoiced’ (without instruction) experimenter-provided organization cueing on memory retrieval. The neuro-physiological basis underlying their memory process was also explored using electroencephalographic (EEG) coherence.;Method. Twenty-three children with high-functioning ASD and 39 normal children (NC) aged 5 to 14 years were recruited. In experiment 1, their memory was assessed with the Hong Kong List Learning Test (HKLLT), a memory test of disorganized (DIS) and semantically organized (ORG) words. In experiment 2, their memory of abstract geometric figure (Rey-O) and nameable object (Object Recognition Test, ORT) was tested. The objects in the ORT were presented in DIS or ORG manner. While semantic cue was given explicitly in the HKLLT, it was delivered implicitly in the ORT. In experiment 3, EEG theta coherences connecting anterior, temporal and posterior brain regions were recorded before and during the ORT.;Results. ASD children showed frontal-lobe-related memory problems, with encoding and retrieval deficits, and vulnerability to interference. Their memory deficits were associated with ineffective use of organization strategies. Hyper-coherence at inter-hemispheric anterior-posterior connections and lesser reduction in intra-left anterior coherence correlated with their poorer recognition. Explicit cueing has enhanced semantic clustering and delayed recall of words. Yet, the effect of ‘unvoiced’ cueing was subtle, with a trend of improving severer memory impairment and suppressing excessive coherence.;Conclusion. The present study revealed specific memory deficits profile of ASD children associated with ineffective use of organization strategies. Together with their deviated EEG coherence pattern, it has implicated that the memory deficits associated with ASD was possibly subserved by dysfunctional cooperation in frontal and frontal-posterior cortical regions. The potential benefits of explicit cueing and subtle effect of implicit cue on memory performance and neural functional cooperation in ASD were discussed.