A new non-invasive neurostimulation technique capable of reaching deep regions of the brain has been used to elucidate the brain’s pain mechanisms, with promising clinical applications in neurology and psychiatry.
Described in a study published in the journal Pain, the technique developed by researchers at Université de Montréal offers a new way to probe neural pain networks, with the prospect of developing effective clinical interventions.
“Until recently, neuromodulation techniques included invasive methods (deep brain stimulation) and non-invasive approaches that had limited ability to reach deep regions of the brain," said Oury Monchi, an UdeM nuclear medicine professor.
"This is particularly true of transcranial magnetic stimulation and transcranial direct current stimulation (tDCS),” said Monchi, who conducts his research at UdeM's Institute of Geriatrics (CRIUGM).
“Transcranial ultrasound stimulation (TUS) presents itself as an innovative alternative, as it uses energy in a non-invasive manner to target deep regions of the brain more precisely and more deeply, particularly those involved in pain,” added PhD student Ali K. Zadeh, the study's first author.
The researchers conducted a double-blind, placebo-controlled experimental trial involving 25 healthy participants aged 18 to 40, to evaluate the effect of TUS on various pain sensitivity tests, specifically targeting two brain regions: the left primary somatosensory cortex (S1) and the left ventropostolateral (VPL) nucleus of the thalamus.
Stimulation of the S1 region turned out to significantly lower the detection threshold and tolerance to thermal pain on the side opposite to the stimulation, reflecting increased pain sensitivity.
At the same time, targeting S1 or VPL resulted in a bilateral decrease in the detection threshold for non-painful heat. By contrast, no significant changes were observed in sensitivity to mechanical pain.
These observations confirm the involvement of the S1-VPL axis in the thermal component of pain, the researchers say.
