Aims: In individuals with Autism Spectrum Disorder (ASD), behavioral findings indicate episodic memory deficits, that are con-substantiated with ERPs studies showing an abnormal pattern of successful retrieval (ERP old-new effect). Episodic retrieval success in typically-developed adults (TDs) is also reflected in theta activity (oscillatory old-new effect). Retrieval processes in ASDs may be associated with functionally distinct retrieval pathways. The present study aims to examine the performance and neuronal patterns related to memory retrieval, inspecting theta activity and ERP components in response to stored conceptual knowledge modulation. Methods: Performance in recognition memory task was compared between TDs and ASDs. Induced oscillatory theta activity was compared at frontal, temporoparietal and mid-line areas for OLD versus NEW images. The ERP analysis was conducted between 300 – 900 ms to compare encoding types (categorical vs. perceptual) and typicality (high vs. low typical) differences. Results: As expected, TDs showed memory-related change in theta synchronicity for the oscillatory old-new effect in a time-window of the late parietal P3 component, also represented in the ERP old-new effect (per conceptual knowledge modulations). In line with previous studies, in ASDs it was observed a significant lower recognition memory performance and importantly it was also observed an atypical old-new effect in memory retrieval. Conclusions: The present study provides evidences for anomalies on recognition memory retrieval on theta-band activity and on ERP components, according the conceptual modulations. Our findings are consistent and con-substantiate previous studies indicating abnormal episodic retrieval processes in ASDs and it may identify neural mechanisms involved in learning processing.

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ASD,prior knowledge,ERP,Oscillations,episodic memory,old-new effect