Characteristic differences in somatosensory gating between adolescents and adults

Aim of the study: To characterize differences in somatosensory gating associated with maturation, we compared the amplitude ratio of responses to the second stimulus (S2) over the first stimulus (S1) between adolescents and young adults using a paired-pulse stimulation paradigm while recording somatosensory-evoked potentials (SEPs). Methods: Thirteen right-handed adolescent males (14.1 ± 0.3 yrs) and twenty-four adult males (21.2 ± 1.2 yrs) participated. We focused on SEP components at Fz and C3', and sensory gating for each component was quantified as the S2/S1 amplitude. Components showing significant gating were identified within each group. Subsequently, S2/S1 amplitude ratios between groups and bivariate correlations among gated components were examined. Results: Adolescents showed significant gating for N30 at Fz and P22 and P45 at C3', and adults showed significant gating for N30 at Fz and P22 and N60 at C3'. The S2/S1 amplitude ratios for N30 at Fz and P45 at C3' were significantly smaller in adolescents than adults, whereas other components did not differ. Correlations among S2/S1 amplitude ratios were not significant in either group, suggesting component-specific mechanisms. Conclusions: Adolescents showed stronger frontal N30 gating and a different centroparietal pattern relative to adults, suggesting immature and region-specific inhibitory processes. The absence of correlations among S2/S1 ratios supports the presence of partially independent generator and neurochemical mechanisms across SEP components. These findings provide a developmental profile of somatosensory gating.