Brain stimulation by using non-invasive technology is a branch of the neurotechnology field Researchers have increasingly used a variety of techniques to modulate the brain without the need for drugs. A relatively new technology that scientists have been testing is called transcranial direct current stimulation (tDCS). This is a method of non-invasive brain stimulation that has very few side effects. It has utility for a variety of different brain based disorders. The basic idea behind this new treatment method is researchers attach two electrodes to certain areas on a person's head and then they allow an extremely small 2 millamp electric current to pass through the electrodes.

This may remind people of the more drastic shock therapy (ECT} but it is much gentler and more selective than that treatment. ECT always requires a person to get anaesthesia to get it. ECT gives a person's brain a giant 600 millamp buzz and this then causes a seizure. ECT affects almost the entire brain and has many negative side effects such as memory loss. tDCS, however, only excites or inhibits brain regions directly underneath the positioned electrode. The electrode that is attached to the (+) anode part of the 9 volt battery is able to increase neuron firing. The electrode that is connected to the (-) cathode decreases neuron activity. So this allows researchers to selectively upregulate or downregulate activity in specific brain areas.

Transcranial direct current stimulation as a tool is very useful for a variety of mental illnesses. A positive aspect to using transcranial direct current stimulation is that it is actually much cheaper to use than the more expensive transcranial magnetic stimulation. It can also be used on a person while they are wide awake and fully conscious. This basically enables a person to use the technology on themselves if they understand what they are doing. The main disadvantages to using tDCS is that it can really only activate brain areas that are near to a person's skull. It cannot reach deep brain areas. Another negative is that it is less selective in its targeting accuracy than other methods of brain stimulation.

When tDCS is applied over an area of the brain called the left dorsolateral prefrontal cortex (LDPFC), scientists have found that they can improve a person's ability to spontaneously generate a list of novel words. tDCS is also able to enhance working memory, the brain's ability to temporarily store and manipulate information. When the LDPFC area is activated it can also help to improve the symptoms of depression in depressed patients. Researchers have already performed a preliminary study on patients with major depression and obtained positive results. tDCS has been used to alter a person's perception of pain, so tDCS may even eventually become a treatment for people who currently have unmanageable pain.

Transcranial direct current stimulation has an enormous number of other different uses. Scientific researchers have done several preliminary studies to test this technology. Researchers have found that tDCS is able to modulate a person's desire for eating foods when it is applied over the DLPFC. So this may eventually be used as a treatment for those who are overweight or obese. Transcranial direct current stimulation has also been used a a brain stimulation method to improve recognition memory in patients who have Alzheimer's disease. So this may become a beneficial treatment for those types of people. tDCS has also been used as a method to reduce craving for smoking. This treatment could be beneficial for people with all sorts of addictions such as alcoholism. Overall transcranial direct current stimulation shows a lot of promise for a variety of different brain disorders.