Cell Phones Stimulate the Motor, but not Sensory, Cortex

It's all over the news: elecrtomagnetic fields (EMFs) from cellular phones have been found to excite the brain close to where the phone is being held. As more than 500 million people in the world use cell phones, it is quite important to clarify the extent of the activation and whether it is harmful. (More under the fold.....)

The most recent study was published in July's Annals of Neurology and investigated the effects of EMF exposure on brain physiology for the first time. The authors exposed 15 volunteers to EMF signals from a GSM900 phone for 45 minutes. Motor evoked potentials (MEPs) were recorded from the motor cortex during, directly after, and one hour after EMF exposure. 12 out of 15 subjects exhibited changes in the motor cortex close to the cell phone.

"Intracortical excitability was significantly modified, short intracortical inhibition was reduced and facilitation enhanced," the authors report. They found that the effects of the EMF were transient and the subjects' brains tended to return toward baseline conditions one hour after the exposure.

In addition, a Japanese group led by Dr. Kaoru Yuasa published a study in April edition of Clinical Neurophysiology which explored the effects of 30 minutes of mobile phone (EMF as well) use on the human sensory cortex. They recorded somatosensory evoked potentials (SEPs) in 12 volunteers before and after 30 minutes of cell phone exposure. They found no change in SEPs, and concluded that 30 minutes of cell phone usage has no short-term effects on the sensory cortex.

So, perhaps limit your calls to 30 minutes? It would be interesting to see if the amount of motor cortex stimulation would drop if limited to 30 minutes.