Complex negative emotions induced by electrical stimulation of the human hypothalamus

Background: Stimulation of the ventromedial hypothalamic region in animals has been reported to cause attack behavior labeled as sham-rage without offering information about the internal affective state of the animal being stimulated. Objective: To examine the causal effect of electrical stimulation near the ventromedial region of the human hypothalamus on the human subjective experience and map the electrophysiological connectivity of the hypothalamus with other brain regions. Methods: We examined a patient (Subject S20_150) with intracranial electrodes implanted across 170 brain regions, including the hypothalamus. We combined direct electrical stimulation with tractography, cortico-cortical evoked potentials (CCEP), and functional connectivity using resting state intracranial electroencephalography (EEG). Results: Recordings in the hypothalamus did not reveal any epileptic abnormalities. Electrical stimulations near the ventromedial hypothalamus induced profound shame, sadness, and fear but not rage or anger. When repeated single-pulse stimulations were delivered to the hypothalamus, significant responses were evoked in the amygdala, hippocampus, ventromedial-prefrontal and orbitofrontal cortices, anterior cingulate, as well as ventral-anterior and dorsal-posterior insula. The time to first peak of these evoked responses varied and earliest propagations correlated best with the measures of resting-state EEG connectivity and structural connectivity. Conclusion: This patient's case offers details about the affective state induced by the stimulation of the human hypothalamus and provides causal evidence relevant to current theories of emotion. The complexity of affective state induced by the stimulation of the hypothalamus and the profile of hypothalamic electrophysiological connectivity suggest that the hypothalamus and its connected structures ought to be seen as causally important for human affective experience. (c) 2022 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Automated summary

This study investigates the causal effect of electrical stimulation near the ventromedial region of the human hypothalamus on subjective experience. The findings suggest that stimulation in this area induces feelings of shame, sadness, and fear, but not rage or anger. The study also reveals the electrophysiological connectivity between the hypothalamus and other brain regions associated with emotional responses.