Mobile Phone Emissions and Human Brain Excitability Florinda Ferreri, MD, 1,2 Giuseppe Curcio, PhD, 1,3 Patrizio Pasqualetti, PhD, 2 Luigi De Gennaro, PhD, 3 Rita Fini, Tech, 1,2 and Paolo Maria Rossini, MD, PhD 1,2,4 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. Ann Neurol 2006;60:188 –196 As digital mobile phone technology is now used by more than 500 million people worldwide and is spreading, scientific interest in its potential impact on human health and performance has significantly in- creased in recent years. 1 Although the biological effects of electromagnetic fields (EMFs) on the overall body have been extensively studied over the past several de- cades, relatively few investigations have focused on more specific biological functions (namely, brain corti- cal excitability) under the influence of electromagnetic time-varying fields in frequency ranges relevant to mo- bile phone emissions applied directly to the human head. The literature contains a few sparse contributions using neurophysiological techniques. However, these studies either evaluate the effects on brain structures at some distance from the EMF source (brainstem, sub- cortical relays, visual pathways) or test the function of auditory relays reflecting contributions from both hemispheres, 2–14 thereby diluting the unilateral effect of EMFs, which are applied mainly to one side of the head, or the studies address the effect of hyperthermia without considering EMF effects. 15,16 The signal generated by the Global System for Mo- bile Communication (GSM), the world’s most exten- sively used system, operates at frequencies around 900MHz and is also the most commonly studied signal in the area of biological effects. To explain the interaction between EMFs and living organisms, researchers have proposed two kinds of mechanisms 17 : thermal and nonthermal. The thermal effects (correlated to radiation intensity) have been studied at great length, and safety guidelines have been produced and imposed by the International Authority to avoid adverse reactions. 18 After GSM-EMF exposure of at least 25 to 30 minutes, temperature changes of about 0.1° C were evaluated empirically at the tym- panic and brain levels, respectively 19 –21 ; this tempera- ture increase has been considered irrelevant for the functional and structural integrity of the brain and largely compensated by the thermo-stabilizing proper- ties of the blood circulating in the head/brain. 22 In contrast, the nonthermal effects of EMFs so far have not been examined in depth, 23,24 even if various mechanisms have been considered, such as the modu- From the 1 Department of Neurology, University Campus Bio- medico; 2 Associazione Fatebenefratelli per la Ricerca, Department of Neuroscience, Hospital Fatebenefratelli, Isola Tiberina; 3 Depart- ment of Psychology, University “La Sapienza,” Rome; and 4 Istituto di Ricovero e Cura a Carattere Scientifico Centro S. Giovanni di Dio, Hospital Fatebenefratelli, Brescia, Italy. Received Nov 27, 2005, and in revised form Apr 29, 2006. Ac- cepted for publication May 2, 2006. Published online Jun 26, 2006 in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/ana.20906 Address correspondence to Dr Rossini, Department of Neuro- science, Hospital Fatebenefratelli, Isola Tiberina 39, 00186 Rome, Italy. E-mail: paolomaria.rossini@afar.it 188 © 2006 American Neurological Association Published by Wiley-Liss, Inc., through Wiley Subscription Services