Mechanisms and State of the Art of Transcranial Magnetic Stimulation

Abstract

In 1985, Barker et al. built a transcranial magnetic stimulation (TMS) device with enough power to stimulate dorsal roots in the spine. They quickly realized that this machine could likely also noninvasively stimulate the superficial cortex in humans. They waited a while before using their device over a human head, fearing that the TMS pulse might magnetically "erase the hard-drive" of the human brain. Almost 10 years later, in 1994, an editorial in this journal concerned whether TMS might evolve into a potential antidepressant treatment. In the intervening years, there has been an explosion of basic and clinical research with and about TMS. Studies are now uncovering the mechanisms by which TMS affects the brain. It does not "erase the hard-drive" of the brain, and it has many demonstrated research and clinical uses. This article reviews the major recent advances with this interesting noninvasive technique for stimulating the brain, critically reviewing the data on whether TMS has anticonvulsant effects or modulates cortical-limbic loops.

Cortisol, depression and reduced cortico-cortical cross-talk in Cushing’s syndrome

“…The involvement of reduced information transfer between different brain regions in depression was recently put forward by Schutter et al (16). These authors argued that the antidepressant effects of clinical studies in depressive patients utilizing fast repetitive transcranial magnetic stimulation over the frontal cortex, commonly argued to be due to enhancement of neuronal activity (17,18), do more likely result from enhanced corticocortical cross-talk (16,19). This suggestion finds strong support in the recent observation of increased cross-talk between the frontal and parietal regions after repetitive transcranial magnetic stimulation over the frontal cortex in healthy volunteers (20).…”

Effect of Low-Frequency rTMS on Electromagnetic Tomography (LORETA) and Regional Brain Metabolism (PET) in Schizophrenia Patients with Auditory Hallucinations

“…The effect of rTMS on the low-resolution brain electromagnetic tomography (LORETA) and brain metabolism ( 18 FDG PET) was measured before and after 2 weeks of treatment. Results: We found a significant im-of rTMS depends on the power of the magnetic field, the localization of the stimuli, and the frequency [2] . Lowfrequency rTMS ( ^ 1 Hz) inhibits the cortical excitability and leads to a weakening of the transfer at the synapses [3,4] .…”

Imaging the Brain Activity Changes Underlying Impaired Visuospatial Judgments: Simultaneous fMRI, TMS, and Behavioral Studies

“…Such inferences can only be made based on a controlled manipulation of brain activity whose impact on behavior or cognition can be quantified. The technique of transcranial magnetic stimulation (TMS) is a well-established tool for inducing transient disruptions of neural activity (''virtual lesions'') noninvasively in human volunteers (Hallett 2000;Pascual-Leone et al 2000;Walsh and Cowey 2000;George et al 2002;Sack 2006). Accordingly, TMS studies have established the relevance of parietal cortices in visuospatial processing (Cohen et al 1996;Topper et al 1998;Rushworth et al 2003;Vannini et al 2004;Kim et al 2005;Koch et al 2005;Go¨bel et al 2006), visuospatial attention (Hilgetag et al 2001;Stewart, Ellison, et al 2001;Mu¨ri et al 2002;Chambers et al 2004;Hung et al 2005;Mevorach et al 2005;Thut et al 2005;Dambeck et al 2006), visuomotor mental rotation (Bestmann et al 2002), and visuomotor integration (Rushworth et al 2001).…”