Neural networks underlying epileptic humming.

PURPOSE

Humming is a rare automatism occurring in partial seizures that has received little attention. Its study could shed light on the neural networks underlying melodic expression. In this study, we examined the anatomoelectroclinical correlates of humming during epileptic seizures

METHODS

Three patients undergoing presurgical stereoelectroencephalography (SEEG) for medically intractable temporal lobe epilepsy were studied. Coherence analysis of SEEG activity was carried out to study the functional coupling of different regions of the brain, whereas time-frequency (TF) analysis was conducted to assess epileptic discharge patterns. Changes in coherence were studied to identify the neural structures/systems implicated in humming.

RESULTS

Humming began after the onset of seizures generated in medial limbic regions of the temporal lobe. At seizure onset, coherence analysis showed an increase in amygdala-hippocampus coupling. Humming began after the onset of a rhythmic discharge over lateral regions of the superior temporal gyrus (STG). A highly significant increase in coherence was observed between prefrontal regions and the STG. TF analysis of the STG discharge showed a reproducible pattern with a single fundamental frequency and associated harmonics. This frequency was approximately 6 Hz for two patients and 15 Hz for one patient.

CONCLUSIONS

These findings suggest that the occurrence of humming during epileptic seizures of the temporal lobe is associated with activity in a neural network involving the STG and the inferior frontal gyrus.