Allelic variation in the serotonin transporter promoter modulates cortical excitability.

摘要

BACKGROUND: Transcranial magnetic stimulation (TMS) is a noninvasive procedure that may be used to study individual differences in motor cortex excitability. Such differences are assumed to reflect serotonergic and other inputs to the motor cortex. METHODS: Here we investigate the impact of a functional polymorphism in the promoter region of the 5-hydroxytryptamine transporter gene (5-HTTLPR) on measures of motor cortex excitability. RESULTS: Sixty healthy subjects carrying one or two copies of the short 5-HTTLPR allele (s/s and s/l) showed a significant reduction in short intracortical inhibition (SICI, p = .012) and an increased cortical silent period (p = .042) compared with 60 age- and sex-matched individuals homozygous for the long allele (l/l). In contrast, motor threshold and intracortical facilitation did not differ significantly between groups. CONCLUSIONS: These results provide further evidence of a role for serotonergic transmission in the modulation of cortical excitability. Differential effects on the measures under study suggest a pattern of prioritization in bioamine regulation of cortical inhibition.