Human hypothalamus shows differential responses to basic motivational stimuli--an invasive electrophysiology study

The hypothalamus supports basic motivational behaviours such as mating and feeding. Recording directly from the posterior inferior hypothalamus in a male patient receiving a deep brain stimulation (DBS) electrode for the alleviation of cluster headache, we tested the hypothalamic response to different classes of motivational stimuli (sexually relevant: pictures of dressed and undressed women; pictures of food) and pictures of common objects as control. Averaged local field potentials (LFP) to sexually relevant stimuli were characterized by a biphasic significantly enhanced response (relative to objects; bootstrapping statistics) with a first phase starting at around 200 ms and a second phase peaking at around 600 ms. Sexually relevant stimuli also showed a greatly enhanced positivity relative to other stimulus classes in surface event-related potentials in a group of 11 male control participants. It is suggested that the hypothalamus is involved in the recruitment of attentional resources by sexually relevant stimuli reflected in this surface positivity. In a second session, the response to food stimuli relative to objects was tested in two states: after fasting for 14 h, LFPs to food and object stimuli showed significant differences in between 300 and 850 ms, which disappeared after a full high-calorie meal, thus replicating classic studies in monkeys [Rolls et al., Brain Res (1976) 111:53-66]. The current data are the first to demonstrate hypothalamic responses to the sight of motivational stimuli in man and thus shows that recording from DBS electrodes might provide important information about the cognitive functions of subcortical structures.