Neural Signatures of Recollection Are Sensitive to Memory Quality and Specific Event Features

Episodic memories reflect a bound representation of multimodal features that can be recollected with varying levels of precision. Recent fMRI investigations have demonstrated that the precision and content of information retrieved from memory engage a network of posterior medial-temporal and parietal regions co-activated with the hippocampus. Yet, comparatively, little is known about how memory content and precision affect common neural signatures of memory captured by EEG, where recollection has been associated with changes in ERP and oscillatory measures of neural activity. Here, we used a multifeature paradigm previously reported [Cooper, R. A., & Ritchey, M. Cortico-hippocampal network connections support the multidimensional quality of episodic memory. eLife, 8, e45591, 2019] with continuous measures of memory, in conjunction with scalp EEG, to characterize the content and quality of information that drives ERP and oscillatory markers of episodic memory. A common signature of memory retrieval in the left posterior regions, called the late positive component, was sensitive to overall memory quality and also to precision of recollection for spatial features. The analysis of oscillatory markers during recollection revealed that alpha/beta desynchronization was modulated by overall memory quality and also by individual features in memory. Importantly, we found evidence of a relationship between these two neural markers of memory retrieval, suggesting that they may represent complementary aspects of the recollection experience. These findings demonstrate how time-sensitive and dynamic processes identified with EEG correspond to overall episodic recollection and also to the retrieval of precise features in memory.