Differential Time Frequency Dynamics in Memory and Prioritization of Value-Directed Stimuli

The ability to preferentially encode and later retrieve valuable information amidst a plethora of miscellaneous information is an essential aspect of human memory. Several hypotheses have been suggested to explain the enhanced ability to successfully encode high value items. These include the hypothesis that the prefrontal executive control processes are engaged for valuable information, producing elaborative rehearsal strategy. Another hypothesis is that greater attentional resources are allocated to higher value items via the reward driven mid-brain dopamine systems interacting with hippocampal and cortical areas to produce enhanced memory. To further understand the neural mechanisms of value on memory, electroencephalogram data under a value-directed remembering paradigm (VDR) was analyzed for oscillatory activity. During the task, participants encoded words assigned a different point value with the instruction to maximize the point value of recognized words during test. To analyze frequency activity during encoding, conditions of subsequent memory as subjective responses of either recollection (i.e., “remember”) and familiarity (i.e., “know”) were assessed. A possible way to observe the allocation of attention resources in the brain are alpha oscillations (8-15 Hz) which are thought to underlie this process. Participants demonstrated superior memory for high versus low value point items. Following the hypothesis that there is a greater recruitment of attentional resources for high value information, alpha oscillatory power in the occipital/temporal cortex displayed significantly more desynchronization for high value compared to low value conditions during encoding. As well, successful retrieval compared with unsuccessful retrieval and subsequent “remember” or “know” conditions resulted in a qualitatively different, more sustained desynchronization of alpha and other unanticipated frequency band oscillations during encoding that are discussed. Taken together, these findings support previous research for alpha-band desynchronization during encoding items of value into memory and potentially open paths to decouple value and memory driven processes.