Developmental models of motor-evoked potential features by transcranial magnetic stimulation across age groups from childhood to adulthood

Abstract

To derive the maturation of neurophysiological processes from childhood to adulthood reflected by the change of motor-evoked potential (MEP) features. 38 participants were recruited from four groups (age mean in years [SD in months], number (males)): children (7.3 [4.2], 7(4)), preadolescents (10.3 [6.9], 10(5)), adolescents (15.3 [9.8], 11(5)), and adults (26.9 [46.2], 10(5)). The navigated transcranial magnetic stimulation was performed on both hemispheres at seven stimulation intensity (SI) levels from sub- to supra-threshold and targeted to the representative cortical area of abductor pollicis brevis muscle. MEPs were measured from three hand- and two forearm-muscles. The input–output (I/O) curves of MEP features across age groups were constructed using linear mixed-effect models. Age and SI significantly affected MEP features, whereas the stimulated side had a minor impact. MEP size and duration increased from childhood to adulthood. MEP onset- and peak-latency dropped in adolescence, particularly in hand muscles. Children had the smallest MEPs with the highest polyphasia, whereas I/O curves were similar among preadolescents, adolescents, and adults. This study illustrates some of the changing patterns of MEP features across the ages, suggesting developing patterns of neurophysiological processes activated by TMS, and to motivate studies with larger sample size.

Home-based arm cycling exercise improves trunk control in persons with incomplete spinal cord injury: an observational study

“…A limitation of our study is the age and sex differences between groups in Experiment 1, given that both factors could influence MEP amplitudes. Research suggests that the effect of age on MEP amplitudes varied between muscles 61 – 63 . For instance, input–output curves of MEPs were different in the first dorsal interosseous but the same in the vastus lateralis between young and older adults 62 .…”

Characteristics of motor evoked potentials in patients with peripheral vascular disease

“…Some studies which compared healthy younger participants with matched healthy older participants, have found both at rest and during contraction, older participants have smaller MEP amplitudes with longer latencies [28,29], the latter in keeping with the results of the current study. However, other studies have demonstrated that the effect of age on MEP amplitudes can vary between muscles [30][31][32]. One study, for example, showed inputoutput curves (stimulus intensity vs MEP amplitudes) of MEPs were different in an upper limb muscle, the first dorsal interosseous muscle, between younger and older adults but were the same for a lower limb muscle, vastus lateralis [31].…”