Transcranial magnetic stimultaion (TMS) is a neuromodulation technique that has been used for 30 years. In this technique, an alternating magnetic field induces an electrical excitation in a provided location of the cortex through electro-magnetic induction. A stimulator that generates a present pulse is linked to a magnetic coil that adheres to the skull. The stimulator contains a capacitor that produces a current circulation with a voltage of as much as 3000 V and a current of approximately 20,000 A. parallel to the head, which in turn leads to depolarization of the cell membrane of neurons and activation of the cortex situated straight under the urethra. This excitation can spread through synapses and subsequent neurons to the structures of the brain with which the provided location of the cortex is linked. TMS therefore allows the brain to be electrically stimulated without electrodes.
Stimulation of the motor cortex in the location that causes the movement of the fingers or toes is carried out in order to examine that in the unconscious client there is no rupture of the spine cord (whether the impulse from the motor cortex can pass through the undamaged cortico-spinal tract). A single impulse used to a proper area of the cortex might disrupt the interactions of nerve cells taking location in this location at the moment– in this way, for example, it is possible to show the involvement of an offered location of the cortex in chosen perceptual processes.
TMS also makes it possible to map connections with the brain– the effects can be seen not only in the stimulated structure, but likewise in the locations to which this structure sends connections, as well as silencing or stimulating the examined area of the cortex. The latter can be attained using not a single impulse, but a series of impulses– the so-called rTMS (repetitive TMS). Pulses provided at a frequency of about 4 Hz have a stimulating result. Such effects last from numerous to numerous lots minutes after completion of stimulation. In the case of inhibitory stimulation, we develop what is called a “virtual sore”, that is, a short-term blockage of the activity of a chosen area of the cortex. The first presentation of the possibility of this method was the temporary inhibition of speech due to “virtual lesion” of the Broc field in healthy volunteers. In a well-known study on brain plasticity, topics were blindfolded for a week and discovered to read Braille. After a week it turned out that tactile stimuli (embossed Braille letters are not responded by the somatosensory cortex, however the visual cortex– there was a plastic reorganization of the brain. It was proved by interrupting the activity of the visual cortex with TMS– the topics were then unable to differentiate Braille letters.
What to treat with TMS?
Professionals have been trying to find restorative applications for TMS for years. Very high hopes were related to the addition of TMS stimulation in neurorehabilitation after a stroke. The most frequently studied version was TMS silencing of interhemispheric inhibition. In the motor and sensory locations of the cerebral cortex, the impact of one hemisphere of the brain on the other is inhibitory. It was believed that, for instance, in the case of unilateral damage to the motor cortex by stroke, the inhibitory impacts from the other, undamaged hemisphere could weaken the plastic modifications that rehab wished to trigger in the undamaged locations around the stroke website. Some efforts have improved the rehab procedure, but there have likewise been numerous failures. Attempts have actually also been made in the treatment of aphasia (weak effect) and overlook (more promising outcomes).
Persistent discomfort reduction has been the topic of a series of experiments in which TMS has been attempted to reduce neuropathic discomfort. In spite of positive results in little experimental groups, the meta-analysis revealed no medical efficacy.
