The Neural Foundations for Memory and Social Cognition in the Human Brain

National Institute Of Mental Health

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Abstract

We have continued to focus on two major divisions of memory: semantic memory composed of our knowledge about concrete objects and abstract ideas, and priming, a form of implicit memory that underlies our ability to recognize objects and words fast and efficiently. During this past year we have concentrated our efforts on addressing outstanding issues concerning how the brain represents the critical object category of food. Our ability to regulate our consumption of food involves both identifying food (is it an apple, lettuce, a piece of cake) as well as evaluating whether it should be eaten at that time, a process that requires assessing relevant properties such as healthfulness and hedonic value. In order to identify how these fine-grained food properties are represented in the brain, we analyzed functional MRI data from 43 participants who viewed images of different food types. A data-driven clustering approach revealed two major brain networks: a prefrontal network composed of fronto-parietal brain regions and a limbic network composed of cortico-limbic and sub-cortical brain regions. Further analysis, using similarity judgments of those foods from a large online sample (N = 487), revealed that the prefrontal network predominantly represented information related to food healthfulness (Carrington et al., Food Quality and Preference, 2024). In another imaging task, we found that neural responses in this prefrontal network were strongly influenced by judgments of food-related self-control (should I eat it now?), while the limbic network was more affected by hedonic food judgments (how rewarding would it be?). These results suggest that, upon viewing food images, behaviorally relevant information is automatically retrieved from distinct brain networks that act as opponent processes in guiding food consumption (Avery et al., Communications Biology, 2025). Although we have learned a lot about how information about concrete objects like animals, tools, and food is represented in the brain, we know very little about how we represent abstract concepts such as justice, democracy, and wisdom. Indeed, whereas the world of concrete objects seems to naturally fall into categories, it is not at all clear whether the same holds for abstract entities. We have recently begun a series of studies to address this issue. Our findings have indicated that, like concrete entities, abstract concepts have a categorical structure characterized by distinct clusters of concepts referring to emotions, quantities, mental attributes, and social terms (Persichetti et al., Frontiers in Psychology, 2024). Future studies will explore how these abstract categories are represented in the brain. Our studies of implicit memory have focused on the behavioral and neural underpinnings of a powerful form of learning known as priming. It has longed been recognized that our ability to identify a stimulus improves with repetition (repetition priming), whereas neural activity decreases (repetition suppression). The finding of improved behavior coupled with decreased neural activity is puzzling. How does less neural activity result in better performance? We are pursuing this question using simultaneous recording of EEG and fMRI data at high field strength using a 7-Tesla MR scanner. This approach, by providing markedly increased temporal and spatial resolution, should provide unique insights into the neural mechanism underpinning this basic form of learning.