Abstract
Many of our decisions are shaped by previously learned values of objects. Despite a great deal of knowledge gained from recent investigations in nonhuman primates (NHPs) (Ghazizadeh et al., 2018, 2021), the neural underpinnings of long-term value memory in humans are not clearly understood. Here, we aimed to address this question in humans using fMRI and EEG. We devised a learning procedure in which participants were trained for three days to learn the value of 40 random abstract fractals. Each fractal was arbitrarily chosen to be associated with a reward or no reward (good vs. bad objects, respectively). The visual discrimination of good and bad objects in the brain was tested before, immediately after the training and a few days or weeks later using fMRI and EEG. Behaviorally, we found well-preserved memories for at least one day after the completion of training sessions, which fade across days and weeks. Our fMRI results indicate that immediately after the training, temporal and parietal areas are involved in good/bad object discrimination in passive viewing. In addition, a long-term value memory of objects is observed in the striatum and orbitofrontal cortex, days after the training. Our EEG results show that following the value training sessions, differential responses to good versus bad objects are elicited in the parietal and temporal cortex. These findings shed light on the neural basis of long-term value-based memories with implications for maladaptive behaviors such as drug addiction and for cross-species comparisons with NHP.