tDCS

Technology review has an interesting article about transcranial direct current stimulation (tDCS)

"The device is simple: a nine-volt battery that's been approved by the Food and Drug Administration for delivering (electricity) across the skin is connected to large flat sponges that are moistened and then applied to the head."

It also mentions about being able to create a device yourself with parts from radioshack.

"Half the people in this room could build this type of device with parts from RadioShack," Wassermann told a crowd at a neurotechnology conference in Cleveland last week.

Transcranial direct current stimulation (tDCS) has several benefits that may make this a fairly useful treatment in the near future. For one thing, it doesn't appear to have the risk of causing a seizure that is associated with transcranial magnetic stimulation (TMS). tDCS can also simultaneously upregulate activity in one area of the brain while decreasing activity in another. The electrode attached to the anode increases brain activity while the electrode attached to the cathode decreases brain activity. For many brain disorders it is common to have certain areas that are overactive or under active compared to a normal brain. So being able to selectively activate or deactivate cortical brain areas at the same time may be beneficial for mental illness.

Scientists are testing tDCS for schizophrenia and depression. Schizophrenics often have what are called negative symptoms. Negative symptoms include apathy, poor attention, poor grooming habits and poor motivation. These symptoms have been associated with under activity of the frontal lobes, particularly a brain area called the left dorsolateral prefrontal cortex. Positive schizophrenic symptoms such as hallucinations may be associated with over activity in different brain areas, like the temporal cortex. So tDCS may be able to up regulate activity in the left dorsolateral prefrontal cortex while simultaneously decreasing activity in the temporal cortex. This could have a substantial impact on a range of schizophrenic symptoms. For depression, tDCS may be able to up regulate activity in the left dorsolateral prefrontal cortex while simultaneously decreasing activity in the right dorsolateral prefrontal cortex. This will likely have a more robust antidepressant effect. TMS can also both increase and decrease activity in brain regions, however it cannot do it simultaneously like tDCS can.

Another benefit to tDCS is that the device is highly portable. This means that scientists can perform brain stimulation on patients while they are on the go, or when they are performing certain tasks. With TMS, it is much harder to do this since TMS is a fairly bulky device and you have to be lying down to get brain stimulation. With tDCS, a much wider variety of experiments become available. For instance recently scientists have used tDCS to reduce subjects propensity to punish unfair behavior in a game.

"Studying social behavior often requires the simultaneous interaction of many subjects. As yet, however, no painless, noninvasive brain stimulation tool existed that allowed the simultaneous affection of brain processes in many interacting subjects. Here we show that transcranial direct current stimulation (tDCS) can overcome these limits. We apply right prefrontal cathodal tDCS and show that subjects' propensity to punish unfair behavior is reduced significantly."

Experiments like this would not be possible with TMS due to the non-portability of the TMS device. So overall, tDCS has many potential uses as a fairly cheap and effective way to alter an individuals brain functioning.