Functional connectivity between frontal/parietal regions and MTL-basal ganglia during feedback learning and declarative memory retrieval.

Feedback assists the memory system in preserving the learnings from ongoing activities and updating it for future retrievals. Thus, the feedback coming from an individual's performance affects the behavior and, thereby, the performance. However, little is known regarding the interactions of learning and memory associated regions. Thus, we employ a combination of functional connectivity and neurovascular approach to explore the significance of these interactions. Our study comprises thirty-five volunteers who undergo a feedback declarative memory task using simultaneous EEG-fMRI data acquisition. Functional connectivity analysis showed that medial temporal lobe (MTL) and basal ganglia possess significant connectivity but differential relationships during feedback learning and memory retrieval. Specifically, Putamen and pallidum (sub-regions of basal ganglia) are the central hubs in these mechanisms. The neurovascular analysis reveals the increased correlation of frontal-alpha and theta powers with the bold activity of MTL during memory retrievals. The results also report the role of the frontal (and parietal) alpha-beta powers in de-synchronization (and synchronization) of the bold activity of caudate; and parietal-theta (frontal-higher-alpha) power in de-synchronization (and synchronization) of bold activity of right accumbens. Hence, the study demonstrates the significant role of the frontal-parietal EEG powers in MTL-basal ganglia relationships and neuronal adaptations during declarative memory retrieval.