fMRI Studies of the Human Hypothalamus

Abstract

The anatomical and functional subdivisions of the hypothalamus have been explored extensively in animals dating back to the early part of the 20th century. The specific nuclei that produce motivated states have been explored and mapped using a variety of techniques. Human studies have met with limited success in localizing these same nuclei because of the limitations of functional magnetic resonance imaging (fMRI)in this region of the brain. We applied novel fMRI techniques to overcome these difficulties and localize the areas of the hypothalamus associated with specific motivated responses such as feeding, sexual, and revulsion behaviors. These motivations have been localized to distinct regions of the hypothalamus in animals but not in humans.

This study employed these methods to robustly measure activity in the

hypothalamus in response to three categories of erotic images corresponding to different sexual preferences. Each category consistently evoked a strong and localizable response in a number of areas of the hypothalamus. In some of these areas the activity evoked was dependent on one or all of: the image category, the subject's sexual orientation, and the subject's gender. These results support the previous work done in animals and anatomical explorations in humans, and the techniques utilized in this study seem to be a viable method of exploring these questions in the hypothalamus.