Brain Stimulation and Neuroscience

Submitted by maprc on Wed, 10/21/2009 - 16:28

The Brain Stimulation and Neuroscience team's research covers a broad ranges of projects. We use advanced neuroscience technology to investigate brain function and to develop innovative treatments.

We are studying potential uses of these techniques in:

Depression
Schizophrenia
Autism and Asperger’s syndrome
Bipolar disorder
Addiction

Imaging

We use a range of advanced imaging techniques, including:

Electroencephalography (EEG)
Near infra-red spectroscopy (NIRS)
Magnetic resonance imaging (MRI)
Diffusion tensor imaging (DTI)
Positron emission tomography (PET)

Investigations using these technologies help us to develop and refine innovative treatments. For example, imaging is used to locate specific treatment site for transcranial magnetic stimulation (TMS), to investigate any brain changes following TMS, and to investigate possible structural brain differences between groups of people with different conditions.

Transcranial Magnetic Stimulation (TMS)

TMS is a relatively new technology which is showing substantial promise as a therapy for a range of conditions.

TMS is a non-invasive treatment which works by using a magnetic field to stimulate nerve cells in superficial areas of the brain. A hand-held, plastic-coated coil is placed close to the scalp of the person receiving TMS treatment. Electrical current passes through the coil, creating a magnetic field that stimulates electrical activity in the nerve tissue below the coil.

The effect of the stimulation varies with the frequency, intensity and orientation. TMS stimulation has been shown to have effects on mood, motor (control of movement) and cognitive (thinking and planning) functioning.

Because it is a non-invasive therapy that is carried out while the person receiving it is awake and alert, TMS has important advantages over older therapies such as electroconvulsive therapy (ECT). These include: low risk of side-effects or serious complications, avoidance of the need for anaesthesia and its associated risks, costs and inconvenience to the patient, lack of the stigma that ECT sometimes carries, and the fact that TMS is suitable for use in medically unwell people who may not be able to tolerate certain medications or ECT.

When TMS is administered over an extended period, it can either increase or decrease activity in certain parts of the brain. This is called repetitive transcranial magnetic stimulation (rTMS). rTMS is used to treat disorders in which parts of the brain are either underactive or overactive, such as depression and schizophrenia. We are also investigating the use of rTMS to treat other disorders, including bipolar disorder, autism, Asperger’s disorder, and substance abuse.

TMS can also be used to investigate how the brain works. This is important for understanding more about psychiatric disorders, and can lead to the development of new and more effective treatments.

Transcranial direct current stimulation (tDCS)

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 a brain cell to fire, but it changes the cells’ resting state and primes them so that when they do fire, there is a greater response than usual. tDCS treatment generally takes approximately 20 minutes per day.

Like TMS, tDCS is a non-invasive technique which does not require any anaesthetic and has minimal side-effects. It has been used to treat chronic pain, epilepsy, stroke, Parkinson’s disease and depression. Currently, it is being investigated as a treatment for depression in people whose symptoms have not been resolved with medication (treatment-resistant depression).

Magnetic Seizure Therapy

Magnetic Seizure Therapy (MST), like ECT, involves the induction of a seizure for therapeutic purposes. The major difference, however, is that in MST the seizure is induced using magnetic stimulation rather than the electrical current that is used in ECT. Magnetic fields are able to pass freely into the brain, making it possible to produce a very focused seizure in a specific area. The widespread nature of the seizures produced by ECT is thought to be responsible for the memory loss that people report following ECT. Therefore, by avoiding the use of direct electrical current and inducing a focal seizure, it is thought that MST will be able to improve depressive symptoms without the memory loss seen in ECT.

MST is a medical procedure performed by doctors. It involves having a general anaesthetic and a muscle relaxant. The brain is then stimulated with a controlled series of magnetic pulses using a coil that is placed at a precise location on the head. The magnetic pulses cause a seizure in the brain which will last up to two minutes. Because of the muscle relaxants and the anaesthetic, patients do not convulse or ‘fit’ and do not feel any pain. Patients wake up five to ten minutes following the procedure.

Deep Brain Stimulation

Deep Brain Stimulation (DBS) is sometimes described as being like a pacemaker for the brain. DBS involves surgically implanting electrodes into very specific areas of the brain and connecting them to a pulse generator in the upper chest. Electricity is then passed from the pulse generator through the electrodes. This is believed to switch off or interrupt electrical circuits in the target areas of the brain.

DBS has been used extensively in the treatment of neurological disorders such as Parkinson’s disease. Recent results from small trials in North America and Europe suggest that DBS may also be helpful in treating obsessive compulsive disorder (OCD) and treatment-resistant major depression (TRD). We are currently investigating whether using DBS in the nucleus accumbens (a specific area of the brain) is an effective treatment for people with severe unremitting TRD.