Brain stimulation techniques are being increasingly used as effective non-invasive ways of studying and modifying brain function.  The two most common techniques to date are Transcranial Magnetic Stimulation (TMS) and transcranial Direct Current Stimulation (tDCS).

 

Transcranial Magnetic Stimulation

TMS as a treatment

Transcranial magnetic stimulation (TMS) is a technology which is an effective treatment for depression and also showing substantial promise as a therapy for a range of other conditions.  TMS is a non-invasive technique which works by using a magnetic field to stimulate brain activity. A hand-held, plastic-coated coil is placed close to the scalp of the person receiving TMS treatment. An electrical current passes through the coil, creating a magnetic field that stimulates electrical activity in the brain below the coil.  TMS stimulation has been shown to have effects on mood, motor (control of movement) and cognitive (thinking and planning) functioning.

Studies have been evaluating the use of TMS in the treatment of patients with depression for over 15 years. The Therapeutic Brain Stimulation Division of MAPrc has been at the centre of a worldwide research effort focused on evaluating and more recently improving the use of TMS treatment for patients with depression. This leading group has conducted an extensive series of clinical trials that have contributed to robustly demonstrating that TMS is an effective treatment. They have also conducted extensive research evaluating the use of potentially new and improved forms of TMS treatment. TMS is now becoming a widely used treatment for depression around the world. There are clinical programs providing TMS treatment globally, including the US, and its place in clinical practice is gradually being refined.

In addition to using TMS in depression, studies are now exploring its use in other disorders including bipolar disorder, autism, Asperger’s disorder and substance abuse. The researchers in theTherapeutic Brain Stimulation Division have conducted, and continue to conduct innovative studies like these, including in depression, autism, schizophrenia, fibromyalgia and obsessive compulsive disorder.

TMS as a research technique

TMS is also widely utilised as a technique in studying normal and abnormal brain activity. When TMS pulses are applied to the muscle area of the brain, a muscle response is produced, for example in the hand, which can be measured and characterised accurately. This allows researchers to study the function of the motor control system. When TMS pulses are applied to other brain regions, they can be used to interfere with or temporarily augment other brain activities allowing study of these brain functions.  Researchers have also combined TMS with brain imaging methods such as EEG and NIRS as a method of studying brain function in non-motor brain regions. When EEG is recorded during a TMS pulse, we can measure the brain’s electrical response to the TMS pulse, which reflects the normal functioning of the brain being stimulated. In a similar way, the brain’s vascular response to stimulation can be measured with NIRS.  Researchers within the Therapeutic Brain Stimulation Division have extensively used TMS-EEG and TMS-NIRS methods to study brain function and the response to TMS in healthy subjects and in a number of illness states including depression, schizophrenia and addiction.

 

transcranial Direct Current Stimulation

Transcranial direct current stimulation (tDCS) is a relatively new brain stimulation technique. It uses a very gentle electrical current (1-2 mA) to change the activity level of cells in specific areas of the brain. The low current is not enough to cause brain cell to fires, rather it is able to make cells more or less likely to fire.  tDCS has potential use as a way of investigating brain function and is most readily being used in the field of cognitive neuroscience.  It is also being explored as a possible treatment for conditions such as schizophrenia, Alzheimer’s disease, chronic pain, epilepsy, stroke, Parkinson’s disease and depression.

Over recent years, the researchers within theTherapeutic Brain Stimulation Division have conducted a careful series of studies demonstrating that tDCS has the potential to modulate and improve aspects of brain cognition, including learning and memory. These studies are ongoing and hopefully will lead to the development of tDCS methods as treatments for disorders with cognitive dysfunction such as schizophrenia, head injury and Alzheimer’s disease.