The use of electricity for medical purposes has been around for centuries, and recent developments in technology have resulted in new techniques for electrical stimulation. One of these techniques is trans-cranial Direct Current Stimulation (tDCS). tDCS is a non-invasive brain stimulation technique that involves applying a low-intensity direct current over the scalp with the aim of modulating neuronal activity in the brain. The intensity of tDCS is typically 1 milliamp (with a maximum intensity of 2.35 milliamps), applied for approximately 10 minutes. The technique has gained popularity in recent years as a potential therapeutic tool for a range of conditions, including depression, anxiety, chronic pain, and cognitive impairment.
During tDCS, two electrodes are placed on the scalp over the region of interest. One electrode is the anode, which is positively charged, and the other is the cathode, which is negatively charged. The anode is placed over the brain region that is to be stimulated, while the cathode is placed over another part of the scalp or body (usually the face or the shoulder). The electrodes are placed over a wet sponge, cloth or cotton ball. The direct current flows from the anode to the cathode and penetrates the brain tissue, altering the excitability of the brain cells in the region.
Studies have shown that tDCS can be effective in modulating spontaneous neuronal firing and can either excite or inhibit the sensorimotor cortex. Excitation is achieved by anodal stimulation, while inhibition is achieved by cathodal stimulation. Anodal stimulation has also been shown to increase both beta and gamma activity in the visual cortex, while cathodal stimulation has decreased beta and gamma activity. The effects of tDCS can last for up to an hour after the stimulation is applied.
tDCS is a promising tool for the treatment of depression. A 2017 meta-analysis of 29 randomised controlled trials found that tDCS was more effective than sham stimulation in reducing depressive symptoms. Another meta-analysis from 2019 found that tDCS had a significant antidepressant effect in patients with major depressive disorder.
tDCS has also been studied as a potential treatment for cognitive impairment, with some studies showing improvements in memory and attention in healthy subjects as well as patients with Alzheimer's disease and traumatic brain injury. In addition, tDCS has been shown to be effective in reducing chronic pain, although the optimal parameters for stimulation are still being investigated.
Overall, tDCS is a promising tool for modulating neuronal activity in the brain. As this technique continues to be studied, it has the potential to offer a safe and effective treatment option for individuals struggling with a range of neurological and psychiatric disorders.
CAUTION: tDCS is a very powerful tool and, if applied incorrectly, can lead to negative side effects. Because of this, tDCS sessions will only be released to suitably qualified clinicians. Read Dave's tDCS Article for more information.
You can read David Siever's article on tDCS for more information.
This Wikipaedia article has more information on the brain's Brodmann Areas.
Wach this video on tDCS, Physiology and Clinical Applications:
