Linguistic processing during repetitive transcranial magnetic stimulation

Abstract

To determine if linguistic processing could be selectively disrupted with repetitive transcranial magnetic stimulation (rTMS), rTMS was performed during a picture-word verification task. Seven right-handed subjects were trained in two conditions: picture-word verification, which required the subject to verify whether the picture of an object matched the subtitle name on the same page, and frame verification, which required subjects to verify whether there was a rectangular frame around the combined object picture and subtitle. Half of the trials were performed during rTMS. The effects of rTMS on performance were evaluated at the following four scalp positions: left anterior (the area where rTMS produced speech arrest), a mirror site on the right, and two positions in the left and right parietal region. Stimulation over the left deltoid muscle served as a control. Subjects had less difficulty in making picture-word matching decisions during unstimulated compared with stimulated trials at the left anterior and posterior positions. No significant difference in accuracy was detected in the frame verification condition, but response times in the frame verification condition were longer with stimulation at the left anterior position. Because rTMS of the dominant hemisphere affected linguistic processing independent of speech motor output, we confirm that rTMS may be used to investigate language and other cognitive functions.

Case mixing and the right parietal cortex: evidence from rTMS

“…To the best of our knowledge, this is the first magnetic stimulation study highlighting that the right parietal cortex is involved in word recognition (but see Flitman et al, 1998, where left but not right parietal stimulation affected picture-word matching). Previous studies that have used TMS in reading tasks have focussed more on regions of the brain that are typically believed to be involved in motor-or linguistic processes, or early visual processing.…”

Renewal of the Neurophysiology of Language: Functional Neuroimaging

“…Converging evidence comes from studies using TMS which have inhibited right hemispheric areas in recovered patients. Flitman et al (121), for instance, showed that magnetic stimulation may affect the compensatory functions of right-sided areas as it induces transient language disorders in these patients. However, contradicting this finding, other results have suggested that inhibition of right-sided premotor regions can improve naming abilities in nonfluent aphasic patients at a very late stage (260).…”

Efficacy of Repetitive Transcranial Magnetic Stimulation (rTMS) in the Treatment of Affective Disorders

“…Applied to the visual cortex for example, strong TMS can produce phosphenes and stimuli of lower intensity induce transient scotomas (Hallett, 2000). Moreover, other functions, such as linguistic processing, can be investigated with rTMS (Flitman et al, 1998). A neuromodulatory effect of subthreshold high-frequency rTMS has been observed in 10 subjects.…”