Paired-pulse transcranial magnetic stimulation: effects of hemispheric laterality, gender, and handedness in normal controls.

This investigation analyzed retrospective normative data from paired-pulse transcranial magnetic stimulation (PP TMS) studies to assess the effects of hemispheric laterality, gender, and handedness on cortical excitability. There were no significant differences between left and right hemisphere responses in either men or women. Likewise, there was no significant difference in findings between men and women, considering each hemisphere separately. There were no significant differences between right-handed individuals and nonright-handed individuals for left or right hemispheric responses in either men or women or for both genders combined. Nevertheless, large intersubject variance and past evidence of cortical excitability modulation by other factors, such as menstrual cycle phase and reproductive hormonal changes in women, suggest a need for further investigations into other potential factors that may contribute to the large variance among healthy individuals.