The Contribution of Endogenous Modulatory Systems to TMS- and tDCS-Induced Analgesia: Evidence from PET Studies
Table 2
A summary of the main findings of the studies investigating the effects of TMS on the dopaminergic system.
Dopaminergic system
Study
Design
Population (n)
Intervention
Result
Fonteneau et al., 2018
Double blind sham-controlled study
Healthy volunteers.
Sham group = 18 Active group = 14
Single tDCS (tDCS) session applied over the dorsolateral prefrontal cortex Dynamic PET scan using [11C] raclopride binding
Active tDCS induced a significant decrease in [11C] raclopride BPND in the striatum when compared with sham tDCS
Jääskeläinen et al., 2014
Clinical study
Healthy volunteers (N = 29) Patients with neuropathic orofacial pain () Subjects were genotyped for the DRD2 gene 957C > T and catechol-O-methyl transferase (COMT) protein Val158Met polymorphisms
Navigated rTMS applied to the S1/M1 cortex. Evaluation of thermal sensitivity and analgesic efficacy.
In healthy subjects, both innocuous and noxious thermal detection thresholds were lowest in 957TT homozygotes rTMS showed analgesic effect only in 957TT homozygote genotype. In patients, the prevalence of 957TT homozygote genotype was higher than in the healthy population. These reported more severe pain than patients with other genotypes
