The BBC says
Mobile phones 'affect the brain'
The paper's from Nora Volkow and colleagues from NIDA in the USA. Volkow's best known for her work on addiction.
47 people got 18FDG Positron Emission Tomography. This method measures brain glucose use as a proxy for how hard cells are working. They say that this makes it better than other kinds of PET which merely measure regional blood flow. I bet they really wanted to do this study with fMRI, because PET scans cost loads, but of course you can't take a cellphone into an MRI scanner.
There were two conditions: a control in which they had a phone stuck to each ear but they were both off, and an active condition in which the right-ear phone was switched on and receiving a call - but muted so they couldn't hear anything. Each subject was scanned twice, once under each condition, ...
