La stimulation magnétique transcrânienne (TMS) semble donner des espoirs prometteurs en ce qui concerne la recherche en neuropsychologie. La TMS est une méthode non invasive de stimulation du système nerveux central qui utilise le principe de l’inductance pour transmettre un courant électrique au travers de la boîte crânienne, permettant ainsi d’interférer directement avec l’activité neuronale. La TMS peut interrompre transitoirement l’activation d’une région précise et créer ce que l’on appelle des « lésions virtuelles », fonctionnelles, grâce à des stimulations répétées et très proches dans le temps. L’intérêt est de mettre en évidence les zones cérébrales concernées par l’accomplissement de certaines tâches cognitives. L’objectif de notre travail est de présenter de manière non exhaustive quelques travaux qui se sont penchés sur la TMS en rapport avec le fonctionnement cognitif (processus visuels, langage, mémoire, fonctions exécutives, reconnaissance des émotions…) principalement chez le sujet sain. D’autre part, la TMS est testée comme traitement de troubles psychiatriques tels que la dépression et de plus en plus dans la schizophrénie ou les troubles anxieux. Certains auteurs rapportent des effets antidépresseurs de la TMS sans conséquence néfaste sur les fonctions cognitives des patients.

Classical neuropsychology relies on patients with irreversible brain lesions and cognitive impairments give informations about normal brain function. Transcranial Magnetic Stimulation (TMS) is a non-invasive method which involves placing an electromagnetic coil on the scalp. A pulse generates a magnetic field and this one passes, unattenuated by the skin and scalp, into the cortex inducing a current which results in neural activity. The technique shows a good temporal resolution and, moreover, because it represents an interference technique, can be said to have excellent functional resolution. For this reason, TMS appears to be a new tool for research in neuropsychology, producing transitory ‘virtual lesion’effects which could help to understand how, when and where cognitive tasks are performed. The purpose of this article is to review recent research using TMS in cognition and neuropsychology, in a non exhaustive way. In safety studies, single TMS over motor cortex can produce simple movements. Several groups have applied TMS to the study of visual processing and found an impaired detection of visual stimuli. In a same way, TMS can disrupt speech when it was delivered in the language dominant hemisphere. Studies on the memory effects of TMS have been conflicting and the results seem to depend on the choice of paradigm and parameters. Other study depicted improvements in executive functioning after TMS on the left middle frontal gyrus or a diminution in reaction time during an analogic reasoning task. Moreover, some facial emotions seem to be less recognizable after TMS. Although TMS seem to be a new tool for neuropsychological investigations in healthy subjects, few studies reported cognitive effects of rTMS treatment in psychiatry. In a therapeutic view, many of these trials have supported a significant effect of TMS, but in some studies the effect is small and short lived. Several groups have reported on the use of rTMS as a treatment in resistant major depression and the impact on cognition functioning. Most of results tend to find no adverse cognitive effects after several weeks of daily rTMS in depressed patients, compared to Electroconvulsivotherapy (ECT). The effects of transcranial magnetic stimulation (TMS) on hallucination severity and neurocognition were studied in a recent study. A statistically significant improvement was observed on a hallucination scale and on one cognitive measure. TMS is a promising tool for cognitive neuroscience and can provide complementary information to the one obtained using neuropsychological tests, and the one obtained using functional imaging techniques, which have superior spatial but inferior temporal resolution.