The olfactory tubercle (TUB), also called the tubular striatum, receives direct input from the olfactory bulb, and along with the nucleus accumbens, is one of the two principal components of the ventral striatum. As a key component of the reward system, the ventral striatum is involved in feeding behavior, but the vast majority of research on this structure has focused on the nucleus accumbens, leaving the TUB's role in feeding behavior understudied. Given the importance of olfaction in food seeking and consumption, olfactory input to the striatum should be an important contributor to motivated feeding behavior. Yet the TUB is vastly understudied in humans, with very little understanding of its structural organization and connectivity. In this study, we analyzed macrostructural variations between the TUB and the whole brain, and explored the relationship between TUB structural pathways and feeding behavior, using body mass index (BMI) as a proxy in females and males. We identified a unique structural covariance between the TUB and the periaqueductal gray (PAG), which has recently been implicated in the suppression of feeding. We further show that the integrity of the white matter tract between the two regions is negatively correlated with BMI. Our findings highlight a potential role for the TUB-PAG pathway in the regulation of feeding behavior in humans.Significance Statement Increasing evidence suggests that olfaction plays an important role in human feeding behavior. However, the neural underpinnings of this role remain relatively unexplored. Here, we examined the structural connectivity of the olfactory tubercle, which has been implicated in both olfaction and reward, using magnetic resonance imaging. We found that a unique connectivity of the olfactory tubercle with the periaqueductal gray was correlated with body mass index. Our findings highlight a potential role for this pathway in the regulation of human feeding behavior.
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