Neurocomputational mechanisms of learning and decision-making and their disruption in addiction

National Institute On Drug Abuse

Investigators

Linked publications, trials & patents

Abstract

Cognitive functions related to learning and decision-making are critical for adaptive behavior. For instance, the sense of smell has a strong influence on motivated behavior, in part, because of the ease with which we form and maintain associations between odors and important events. The basic neurocomputational mechanisms underlying these cognitive functions in humans and how they are disrupted in neuropsychiatric conditions are not well understood. This project studies these questions directly in humans, by investigating cognitive functions related to learning, behavior, and olfaction. To achieve our goals, we design behavioral tasks that isolate specific cognitive functions. We then determine the neural processes and representations that support them by utilizing non-invasive neural recording techniques such as high-resolution functional magnetic resonance imaging. In addition, to probe the causal contribution of brain areas and networks to these functions, we utilize non-invasive neuromodulation techniques such as transcranial magnetic stimulation. In addition, we perform studies in patient populations to examine whether and how these behavioral and neural processes are altered in neuropsychiatric disorders. In the last year, we published four original research articles summarized below: 1. We developed a novel task to isolate the information content encoded in distributed midbrain responses to errors in reward identity predictions. We found that midbrain activity encodes the identity of unexpectedly received outcomes, but not the identity of unexpectedly omitted outcomes, which were represented in medial frontal cortex. 2. We studied expectancy-related changes in firing of dopamine neurons in rats with lesions of the hippocampus. We found that the hippocampus is necessary for contributing information about upper-level hidden task states to dopamine error signals. 3. We used fMRI in sleeping infants to characterize olfactory brain responses in young infants. We found robust odor-evoked responses in olfactory cortical areas and the thalamus but no evidence for odor coding in distributed activity patterns, a hallmark of adult olfaction. 4. We used diffusion MRI to study the white-matter connections between the lateral olfactory tract and amygdala subregions. We found a higher density of streamline connections between the olfactory tract and the medial nucleus, the anterior cortical nucleus, the central nucleus, and the periamygdala complex compared to the basomedial nucleus, the basolateral nucleus, the lateral nucleus, and the posterior cortical nucleus.