Hospitals and airplanes ban the use of cell phones, because their electromagnetic transmissions can interfere with sensitive electrical devices. Could the brain also fall into that category? Of course, all our thoughts, sensations and actions arise from bioelectricity generated by neurons and transmitted through complex neural circuits inside our skull. Electrical signals between neurons generate electric fields that radiate out of brain tissue as electrical waves that can be picked up by electrodes touching a person's scalp. Measurements of such brainwaves in EEGs provide powerful insight into brain function and a valuable diagnostic tool for doctors. Indeed, so fundamental are brainwaves to the internal workings of the mind, they have become the ultimate, legal definition drawing the line between life and death.
Brainwaves change with a healthy person's conscious and unconscious mental activity and state of arousal. But scientists can do more with brainwaves than just listen in on the brain at work-they can selectively control brain function by transcranial magnetic stimulation (TMS). This technique uses powerful pulses of electromagnetic radiation beamed into a person's brain to jam or excite particular brain circuits.
Although a cell phone is much less powerful than TMS, the question still remains: Could the electrical signals coming from a phone affect certain brainwaves operating in resonance with cell phone transmission frequencies? After all, the caller's cerebral cortex is just centimeters away from radiation broadcast from the phone's antenna. Two studies provide some revealing news.
The first, led by Rodney Croft, of the Brain Science Institute, Swinburne University of Technology in Melbourne, Australia, tested whether cell phone transmissions could alter a person's brainwaves. The researchers monitored the brainwaves of 120 healthy men and women while a Nokia 6110 cell phone—one of the most popular cell phones in the world—was strapped to their head. A computer controlled the phone's transmissions in a double-blind experimental design, which meant that neither the test subject nor researchers knew whether the cell phone was transmitting or idle while EEG data were collected. The data showed that when the cell phone was transmitting, the power of a characteristic brain-wave pattern called alpha waves in the person's brain was boosted significantly. The increased alpha wave activity was greatest in brain tissue directly beneath to the cell phone, strengthening the case that the phone was responsible for the observed effect.
Alpha Waves of Brain
Alpha waves fluctuate at a rate of eight to 12 cycles per second (Hertz). These brainwaves reflect a person's state of arousal and attention. Alpha waves are generally regarded as an indicator of reduced mental effort, "cortical idling" or mind wandering. But this conventional view is perhaps an oversimplification. Croft, for example, argues that the alpha wave is really regulating the shift of attention between external and internal inputs. Alpha waves increase in power when a person shifts his or her consciousness of the external world to internal thoughts; they also are the key brainwave signatures of sleep.
Cell Phone Insomnia
If cell phone signals boost a person's alpha waves, does this nudge them subliminally into an altered state of consciousness or have any effect at all on the workings of their mind that can be observed in a person's behavior? In the second study, James Horne and colleagues at the Loughborough University Sleep Research Centre in England devised an experiment to test this question. The result was surprising. Not only could the cell phone signals alter a person's behavior during the call, the effects of the disrupted brain-wave patterns continued long after the phone was switched off.