Coil design for real and sham transcranial magnetic stimulation

Transcranial magnetic stimulation (TMS) can be used to excite the human cortex noninvasively. TMS also activates scalp muscles and sensory receptors; additionally, the loud sound from the stimulating coil activates auditory pathways. These side effects complicate the interpretation of the results of TMS studies. For control experiments, the authors have designed a coil that can produce both real and sham stimulation without moving the coil. The sham TMS is similar to the real TMS, except for the different relative direction of the currents in the two loops of the figure of eight coil. While the real TMS elicited activation of hand muscles, sham TMS had no such effect; however, the auditory-evoked potentials were similar.

[1]  L. Heller,et al.  Brain stimulation using electromagnetic sources: theoretical aspects. , 1992, Biophysical journal.

[2]  P. Ravazzani,et al.  Theory of multichannel magnetic stimulation: toward functional neuromuscular rehabilitation , 1999, IEEE Transactions on Biomedical Engineering.

[3]  Alan C. Evans,et al.  Transcranial Magnetic Stimulation during Positron Emission Tomography: A New Method for Studying Connectivity of the Human Cerebral Cortex , 1997, The Journal of Neuroscience.

[4]  Jeremy M. Shefner,et al.  Magnetic stimulation in clinical neurophysiology Edited by Sudhansu Chokroverty, MB Boston, Butteworths, 1990 308 pp, Illustrated, $54.95 , 1991 .

[5]  D. Claus,et al.  Safety of rapid-rate transcranial magnetic stimulation: heart rate and blood pressure changes. , 1997, Electroencephalography and clinical neurophysiology.

[6]  Risto Näätänen,et al.  Separation of contamination caused by coil clicks from responses elicited by transcranial magnetic stimulation , 1999, Clinical Neurophysiology.

[7]  A. Barker.  An Introduction to the Basic Principles of Magnetic Nerve Stimulation , 1991, Journal of clinical neurophysiology : official publication of the American Electroencephalographic Society.

[8]  V. Nikouline,et al.  The role of the coil click in TMS assessed with simultaneous EEG , 1999, Clinical Neurophysiology.

[9]  R. Ilmoniemi,et al.  Neuronal responses to magnetic stimulation reveal cortical reactivity and connectivity , 1997, Neuroreport.

[10]  C. A. Marzi,et al.  Transcranial magnetic stimulation selectively impairs interhemispheric transfer of visuo-motor information in humans , 1998, Experimental Brain Research.

[11]  V. Amassian,et al.  Magnetic coil stimulation of straight and bent amphibian and mammalian peripheral nerve in vitro: locus of excitation. , 1993, The Journal of physiology.

[12]  J. Lorberbaum,et al.  Echoplanar BOLD fMRI of brain activation induced by concurrent transcranial magnetic stimulation. , 1998, Investigative radiology.

[13]  Ichiro Kanazawa,et al.  Shortening of simple reaction time by peripheral electrical and submotor-threshold magnetic cortical stimulation , 1997, Experimental Brain Research.

[14]  I. Tarkka,et al.  CHARACTERISTICS OF THE SILENT PERIOD AFTER TRANSCRANIAL MAGNETIC STIMULATION , 1994, American journal of physical medicine & rehabilitation.

[15]  Á. Pascual-Leone,et al.  Rapid-rate transcranial magnetic stimulation of left dorsolateral prefrontal cortex in drug-resistant depression , 1996, The Lancet.

[16]  Mark Hallett,et al.  Daily repetitive transcranial magnetic stimulation (rTMS) improves mood in depression , 1995, Neuroreport.

[17]  S. Zeki,et al.  The consequences of inactivating areas V1 and V5 on visual motion perception. , 1995, Brain : a journal of neurology.