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Difference between revisions of "Transcranial Magnetic Stimulation and Brain Plasticity in Post-Stroke Recovery"
Transcranial Magnetic Stimulation and Brain Plasticity in Post-Stroke Recovery (view source)
Revision as of 10:15, 14 October 2024
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(Created page with " Paolo Maria Rossini, Flavia Pauri thumb|Figure 1:Transcranial Magnetic Stimulation (TMS) is a completely harmless technique that allows specific areas of the brain to be stimulated. By generating magnetic fields (1.5 - 2 tesla) of very short duration (< 1 msec) inside a toroid made of copper coils, and bringing the same close to the scalp, a very short-duration current is induced in the underlying brain, with the opposite direction to the...") |
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Paolo Maria Rossini, Flavia Pauri | Paolo Maria Rossini, Flavia Pauri | ||
[[File:MagStim.jpeg|thumb|'''Figure 1:''' Magnetic Stimulation]] | |||
Transcranial Magnetic Stimulation (TMS) is a completely harmless technique that allows specific areas of the brain to be stimulated. By generating magnetic fields (1.5 - 2 tesla) of very short duration (< 1 msec) inside a toroid made of copper coils, and bringing the same close to the scalp, a very short-duration current is induced in the underlying brain, with the opposite direction to the current circulating in the toroid, without activating the nociceptors of the skin, muscles, or meninges. This results in painless excitation of the neurons beneath the toroid. TMS allows mapping the connections of the motor system and defining its excitability. The evoked response can be derived from various muscles of the body, including those of the masticatory apparatus. In fact, stimulation of the scalp about 2 cm laterally to the central point of the scalp, identified as Cz according to the International 10-20 System of Jasper, evokes an electromyographic response recordable in the pterygoid and masseter muscles contralateral to the stimulated cortical area. | |||
==Multiple Motor Cortical Maps== | ==Multiple Motor Cortical Maps== | ||
[[File:Figure 1 (Rossini).jpg|thumb| | [[File:Figure 1 (Rossini).jpg|thumb|'''Figure 2 :''' Map of cortical motor output to the upper limb after transcranial magnetic stimulation of the contralateral hemisphere. The neuron pools that govern the various muscle groups have different excitability, accompanied by different representation on the scalp. Some muscles tend to organize into “clusters,” aggregating into maps that extensively overlap each other, along with well-defined and separate hot-spot zones (point from which a motor response of minimum latency and maximum amplitude can be elicited (from: Rossini PM, Pauri F. Neuromagnetic integrated methods tracking human brain mechanisms of sensorimotor areas 'plastic' reorganization. Brain Res Brain Res Rev. 2000 Sep;33(2-3):131-54)]] | ||
Different body parts, such as the arm, leg, or face, have predominant representation in specific brain areas, but the representations of muscles of the same body part may overlap. In this respect, the motor cortex differs from the sensory cortex, which is organized in a simpler topography. For example, the cortical motor activity maps for the muscles that move different fingers are essentially the same, while in the sensory cortex, different fingers are represented separately, like the keys of a piano. Recent studies conducted at our center using TMS, stimulating the motor cortex and recording the motor response evoked from 12 muscles of the upper limb, have demonstrated that the neuron pools that govern various muscle groups have different excitability, accompanied by different scalp representation. Some muscles, in fact, showed a tendency to organize into “clusters,” aggregating into maps that widely overlapped each other, along with well-defined and separate hot-spot zones (point from which a motor response of minimum latency and maximum amplitude can be elicited) (Rossini and Pauri 2000, Fig.2). | Different body parts, such as the arm, leg, or face, have predominant representation in specific brain areas, but the representations of muscles of the same body part may overlap. In this respect, the motor cortex differs from the sensory cortex, which is organized in a simpler topography. For example, the cortical motor activity maps for the muscles that move different fingers are essentially the same, while in the sensory cortex, different fingers are represented separately, like the keys of a piano. Recent studies conducted at our center using TMS, stimulating the motor cortex and recording the motor response evoked from 12 muscles of the upper limb, have demonstrated that the neuron pools that govern various muscle groups have different excitability, accompanied by different scalp representation. Some muscles, in fact, showed a tendency to organize into “clusters,” aggregating into maps that widely overlapped each other, along with well-defined and separate hot-spot zones (point from which a motor response of minimum latency and maximum amplitude can be elicited) (Rossini and Pauri 2000, Fig.2). | ||