Objective:
To test-via transcranial magnetic stimulation (tms)-the excitability of each brain hemisphere after 'real' or 'sham' exposure to the electromagnetic field (emf) generated by a mobile phone operating in the global system for mobile communication (gsm).
Methods:
Fifteen male volunteers attended two experimental sessions, one week apart, in a cross-over, double-blind paradigm. in one session the signal was turned on (emf-on, real exposure), in the other it was turned off (emf-off, sham exposure), for 45 minutes. motor evoked potentials (meps) were recorded using a paired-pulse paradigm (testing intracortical excitability with 1 to 17 ms interstimulus intervals), both before and at different times after exposure to the emf. short intracortical inhibition (sici) and facilitation (icf) curves were evaluated both on the exposed and non-exposed hemispheres. tympanic temperature was collected during each session.
Results:
The intracortical excitability curve becomes significantly modified during real exposure, with sici being reduced and icf enhanced in the acutely exposed brain hemisphere as compared to the contralateral, non-exposed hemisphere or to sham exposure. tympanic temperature showed no significant main effect or interactions.
Interpretation:
These results demonstrate that gsm-emfs modify brain excitability. possible implications and applications are discussed.