From: CumbyCrawfish  (Original Message)

Sent: 1/21/2005 3:59 AM

Originally posted by Zuchini Flower at MGH's Brain Talk Communities [www.braintalk.org], I found this very interesting! Ron   Improved recipe for magnetic brain stimulation Transcranial magnetic stimulation (TMS), in which the brain is stimulated using a magnetic coil held outside the skull, has shown some promise in both studying the brain and in treating mental disorders such as depression, epilepsy, and Parkinson's disease. Such magnetic fields induce tiny electrical currents inside the skull that alter the activity of neural pathways. While TMS offers the advantages of relative safety and noninvasiveness, the results of its use in both research and treatment have been disappointing. In human studies, neurological effects of TMS have been transient, rarely lasting longer than 30 minutes. Now, researchers led by John Rothwell of the Institute of Neurology at University College London have devised a new TMS method that produces rapid, consistent, and controllable changes in the motor cortex of humans that last more than an hour. Their findings offer the potential for both more useful research studies using TMS as well as greater therapeutic application. In their studies, the researchers applied various patterns of repetitive magnetic pulses to the scalps of volunteer subjects. They aimed the pulses at the motor cortex that controls muscle response, because effects on the motor cortex can be objectively measured by recording the amount of electrical muscle response to stimulation. Specifically, the researchers positioned the magnetic coil over the motor cortex area that controls hand movement, and they measured response by determining the amount of muscle response in a small muscle in the subjects' hands. The researchers recognized the ethical issue of experimenting on healthy human subjects who had nothing to gain from such experiments. So, they began their studies with stimulations of smaller intensities and lower frequencies than they ultimately used in the experiments. Those initial tests showed that there were no long-lasting or side effects from such stimulations. In their experiments, the researchers found that they could produce controllable, consistent, and long-lasting effects using short bursts of low-intensity pulses over a period of 20 to 190 seconds. Significantly, the researchers found they could overcome the shortcomings of previous stimulation approaches that produced a mix of both excitation and inhibition of transmission of signals between neurons in the brain. The researchers discovered that the excitatory effect of TMS builds up rapidly, within about a second, while the inhibitory effect builds up within several seconds. Thus, by adjusting the length of stimulation, they could favor excitatory or suppressive effects on the brain. "We have found these stimulation paradigms to be safe in normal subjects and capable of producing consistent, rapid, and controllable electrophysiological and behavioral changes in the function of the human motor system that outlast the period of stimulation by more than 60 minutes" concluded the scientists. "The method may prove useful not only in the motor cortex but also in other regions of the brain for both the study of normal human physiology and for therapeutic manipulation of brain plasticity," they concluded. ### Ying-Zu Huang, Mark J. Edwards, Elisabeth Rounis, Kailash P. Bhatia, and John C. Rothwell: "Theta Burst Stimulation of the Human Motor Cortex" The members of the research team include Ying-Zu Huang of the Institute of Neurology at University College London and the Chang Gung Memorial Hospital in Taipei City, Taiwan; and Mark J. Edwards, Elisabeth Rounis, Kailash P. Bhatia, and John C. Rothwell of the Institute of Neurology at University College London. This work was funded by the Medical Research Council. The context and implications of this work are discussed in a Preview by Walter Paulus. Publishing in Neuron, Volume 45, Number 2, January 20, 2005, pages 201–206.

Go To Replies

First  Previous  2-3 of 3  Next  Last  Delete Replies

Reply

Recommend Delete    Message 2 of 3 in Discussion

From: CumbyCrawfish Sent: 1/21/2005 4:02 AM   Originally posted by Zuchini Flower at MGH's Brain Talk Communities [www.braintalk.org], ================================= Magnetic Stimulation Alters Brain -- Robert Preidt THURSDAY, Jan. 20 (HealthDayNews) -- Just two minutes of magnetic stimulation can alter the brain for an hour, according to a University of College London (UCL) study in the Jan. 20 issue of Neuron. The UCL team has been studying methods to improve a technique called transcranial magnetic stimulation (TMS). They're currently exploring the use of their adapted version of TMS as a possible treatment for Parkinson's disease or stroke. In this study, the researchers outline how they found ways to improve TMS so that only a brief period of stimulation produces effects on the brain that last for an hour or more. Longer-lasting effects may enable TMS to be used to modify brain activity in order to treat a wide range of brain problems, ranging from depression to brain damage. TMS involves the use of a magnetic coil that's held outside the skull. This coil, which can be moved over different parts of the head, creates magnetic fields that induce tiny electrical currents inside the brain. These electrical currents alter the activity of neural pathways, stimulating or inhibiting activity in different areas of the brain. "Now that we have improved the technique, we can use it to explore whether stimulation of damaged areas in stroke patients' brains can help speed up their recovery," Prof. John Rothwell, of UCL's Institute of Neurology, said in a prepared statement. "Alternatively, it may be that, in some patients, the 'healthy' side of the brain interferes with recovery by the damaged side, so that another approach would be to reduce its activity and stop it competing for control," he added.

Reply

Recommend Delete    Message 3 of 3 in Discussion

From: CumbyCrawfish Sent: 1/21/2005 4:05 AM Originally posted by Zuchini Flower at MGH's Brain Talk Communities [www.braintalk.org], ================================= Brain Magnet Alters Function for Hours New method could allow use of transcranial magnetic stimulation for treating neurological disorders Betterhumans Staff 1/19/2005 5:13 PM A new method of stimulating the brain with magnets can cause changes that last hours, promising new treatments for people suffering from such conditions as stroke and Parkinson's. UK researchers at University College London have been working to improve transcranial magnetic stimulation (TMS), which involves stimulating the brain using a magnetic coil held outside the skull and moved over different areas. The magnetic fields induce electrical currents in the skull that alter the activity of neural pathways, activating or inhibiting different parts of the brain. TMS has mostly been used for research but is now attracting attention for treating such brain conditions as depression and epilepsy. It is noninvasive and doesn't require hospitalization. The effects, however, are transient, rarely lasting longer than 30 minutes. Rothwell and colleagues appear to have overcome this problem. Rapid action, long lasting The researchers found that the excitatory effect of TMS builds up rapidly, within a second or so, while the inhibitory effect builds up within several seconds. So by adjusting the length of stimulation they were able to choose between stimulating or inhibiting effects. Testing the approach in volunteers, the researchers delivered different patterns of repetitive magnetic pulses to the scalp over a period of 20 to 190 seconds. They aimed the pulses at the motor cortex because the effects on the motor cortex can be objectively measured by recording electrical muscle response to stimulation. In this case, they tested the region responsible for hand movement and measured muscle response in a small muscle in the hand. Using their new approach, the researchers could produce rapid, consistent and controllable changes in the motor cortex that lasted twice as long as conventional TMS. And tests so far have shown that there are no long-lasting side-effects from the technique. "Now that we have improved the technique, we can use it to explore whether stimulation of damaged areas in stroke patients' brains can help speed up their recovery," says Rothwell. "Alternatively, it may be that in some patients the 'healthy' side of the brain interferes with recovery by the damaged side, so that another approach would be to reduce its activity and stop it competing for control." Abstract: http://www.neuron.org/content/artic...896627304008463

Ron Crawford