Tonic thermonociceptive stimulation selectively modulates ongoing neural oscillations in the human posterior insula: Evidence from intracerebral EEG

ABSTRACT The human insula is an important target for spinothalamic input, but there is still no consensus on its role in pain perception and nociception. In this study, we show that the human insula exhibits activity preferential for sustained thermonociception. Using intracerebral EEG recorded from the insula of 8 patients (2 females) undergoing a presurgical evaluation of focal epilepsy (53 contacts: 27 anterior, 26 posterior), we “frequency‐tagged” the insular activity elicited by sustained thermonociceptive and vibrotactile stimuli, by periodically modulating stimulation intensity at a fixed frequency of 0.2Hz during 75s. Both types of stimuli elicited an insular response at the frequency of stimulation (0.2Hz) and its harmonics, whose magnitude was significantly greater in the posterior insula compared to the anterior insula. Compared to vibrotactile stimulation, thermonociceptive stimulation exerted a markedly greater 0.2Hz modulation of ongoing theta‐band (4–8Hz) and alpha‐band (8–12Hz) oscillations. These modulations were also more prominent in the posterior insula compared to the anterior insula. The identification of oscillatory activities preferential for thermonociception could lead to new insights into the physiological mechanisms of nociception and pain perception in humans.