Cortical Reinstatement Mediates the Relationship between Content-specific Encoding Activity and Subsequent Recollection Decisions Materials and Methods

Episodic recollection entails the conscious remembrance of event details associated with previously encountered stimuli. Recollection depends on both the establishment of cortical representations of event features during stimulus encoding and the cortical reinstate-ment of these representations at retrieval. Here, we used multivoxel pattern analyses of functional magnetic resonance imaging data to examine how cortical and hippocampal activity at encoding and retrieval drive recollective memory decisions. During encoding, words were associated with face or scene source contexts. At retrieval , subjects were cued to recollect the source associate of each presented word. Neurally derived estimates of encoding strength and pattern reinstatement in occipitotemporal cortex were computed for each encoding and retrieval trial, respectively. Analyses demonstrated that (1) cortical encoding strength predicted subsequent memory accuracy and reaction time, (2) encoding strength predicted encoding-phase hippocampal activity, and (3) encoding strength and retrieval-phase hippocampal activity predicted the magnitude of cor-tical reinstatement. Path analyses further indicated that cortical rein-statement partially mediated both the effect of cortical encoding strength and the effect of retrieval-phase hippocampal activity on subsequent source memory performance. Taken together, these results indicate that memory-guided decisions are driven in part by a pathway leading from hippocampally linked cortical encoding of event attributes to hippocampally linked cortical reinstatement at retrieval. Introduction When confronted with environmental stimuli, we often make decisions that are guided by the recollection of contextual and other associated details surrounding previous encounters with the stimuli. Much neuroimaging research is concerned with the neural mechanisms that support such recollective decisions sets of findings concerning the functional neuro-biology of recollection are of relevance to the present study. One examines how stronger content-specific cortical representations at encoding are correlated with more accurate decisions at retrieval (e. Rissman, et al. 2012), suggesting that recollective decisions are partially dependent on the initial neural representation of associated details or event attributes. Another examines how content-specific cortical representations at encoding are Wheeler et al. 2006), suggesting that recollective decisions are also dependent on the reactivation of cortical patterns that initially represented associated details. A third examines how activity in the hippocampus supports both the encoding 2006) of associations. Although these 3 phenomena have been independently demonstrated, limited work has examined the relationship between the strength of neural representations at encoding, reinstatement of neural representations at retrieval, and memory performance. In the present study, we used functional magnetic resonance imaging (fMRI) and multivoxel pattern analyses (MVPA) (Haxby et al. …