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

与学习和决策相关的认知功能对适应性行为至关重要。例如，嗅觉对动机行为有很强的影响，部分原因是我们很容易在气味和重要事件之间形成并保持联系。人类这些认知功能背后的基本神经计算机制，以及它们在神经精神疾病中是如何被破坏的，目前还没有得到很好的理解。该项目通过研究与学习、行为和嗅觉相关的认知功能，直接在人类身上研究这些问题。为了实现我们的目标，我们设计了孤立特定认知功能的行为任务。然后，我们利用非侵入性神经记录技术（如高分辨率功能性磁共振成像）确定支持它们的神经过程和表征。此外，为了探索大脑区域和网络对这些功能的因果贡献，我们利用非侵入性神经调节技术，如经颅磁刺激。此外，我们在患者群体中进行研究，以检查这些行为和神经过程是否以及如何在神经精神疾病中改变。

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 two review articles and two collaborative research manuscripts describing the results of experiments on neural representations underlying odor-reward associations and olfactory navigation. The first collaborative study trained rats to learn odor-reward associations either while recording single-unit activity or while imaging calcium flux in the lateral orbitofrontal cortex (OFC). Replicating previous work, single-unit activity contained information about both the sensory properties of odor cues and the rewards they predict, whereas the calcium signal provided only a degraded estimate of the information available in the single-unit spiking, reflecting primarily reward value. The second collaborative study used olfactometry, virtual reality software, and fMRI to investigate whether humans can navigate a virtual olfactory landscape by learning the spatial relationships among discrete odor cues and integrating this knowledge into a spatial map encoded in the entorhinal cortex. Over the course of training, participants improved their performance on the odor navigation task by taking more direct paths toward targets and completing trials faster. fMRI data revealed the emergence of grid-like responses in entorhinal and piriform cortices that were attuned to the same grid orientation, suggesting the presence of a brain network dedicated to olfactory navigation.