Effects of coil design on delivery of focal magnetic stimulation. Technical considerations

Cohen, Leonardo G.; Roth, Bradley J.; Nilsson, Jan; Dang, Nguyet; Panizza, Marcela; Bandinelli, Stefania; Friauf, Walter S.; Hallett, Mark

doi:10.1016/0013-4694(90)90113-x

Cited by 370 publications

(189 citation statements)

References 10 publications

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“…We chose this coil because it produces a magnetic-field maximum of sufficiently small width to allow stimulation of the dorsal premotor cortex without encroaching on the primary motor cortex. A similar coil was previously found to stimulate an estimated volume of 20 ϫ 20 ϫ 10 mm (Cohen et al, 1990;Maccabee et al, 1990;Wassermann et al, 1996). Subjects used a bite bar during stimulation while a mechanical arm held the coil over the target locations.…”

Section: Methodsmentioning

confidence: 99%

Role of the Primary Motor and Dorsal Premotor Cortices in the Anticipation of Forces during Object Lifting

Chouinard¹,

Leonard²,

Paus³

2005

J. Neurosci.

159

113

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When lifting small objects, people apply forces that match the expected weight of the object. This expectation relies in part on information acquired during a previous lift and on associating a certain weight with a particular object. Our study examined the role of the primary motor and dorsal premotor cortices in predicting weight based either on information acquired during a previous lift (no-cue experiment) or on arbitrary color cues associated with a particular weight (cue experiment). In the two experiments, subjects used precision grip to lift two different weights in a series of trials both before and after we applied low-frequency repetitive transcranial magnetic stimulation over the primary motor and dorsal premotor cortices. In the no-cue experiment, subjects did not receive any previous information about which of two weights they would have to lift. In the cue experiment, a color cue provided information about which of the two weights subjects would have to lift. Our results demonstrate a double dissociation in the effects induced by repetitive stimulation. When applied over the primary motor cortex, repetitive stimulation disrupted the scaling of forces based on information acquired during a previous lift. In contrast, when applied over the dorsal premotor cortex, repetitive stimulation disrupted the scaling of forces based on arbitrary color cues. We conclude that the primary motor and dorsal premotor cortices have unique roles during the anticipatory scaling of forces associated with the lifting of different weights.

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Section: Methodsmentioning

confidence: 99%

Role of the Primary Motor and Dorsal Premotor Cortices in the Anticipation of Forces during Object Lifting

Chouinard¹,

Leonard²,

Paus³

2005

J. Neurosci.

159

113

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“…We used a ®gure-ofeight coil, each winding measuring 7 cm (maximum output 2 T) producing the maximum electric ®eld below its center and so the zone of stimulation is more focal [20]. The center of the coil was positioned over the cortical site to be stimulated (left parietal, right parietal or right frontal) in a parasagittal line with the handle pointing posteriorly.…”

Section: Tms: the Equipment Consisted Of A Magstim Model 200mentioning

confidence: 99%

Event-related TMS over the right posterior parietal cortex induces ipsilateral visuo-spatial interference

Vandermeeren¹,

Olivier²,

Gelder³

2001

Neuroreport

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The right posterior parietal cortex (PPC) is implicated in visuo-spatial processing, as illustrated by patients with visuo-spatial neglect, but the precise time-course of its contribution is still an open question. In the present study we assessed whether single-pulse transcranial magnetic stimulation (TMS) can interfere with the performance of normal subjects in a standard visuo-spatial task. Participants had to perform a landmark task while TMS was applied over the right PPC, the homologue region in the left hemisphere or the right primary motor cortex. Stimulation was time-locked to the stimulus presentation with a stimulus onset asynchrony (SOA) varying between 50 and 200 ms. Our results indicate that TMS interfered mainly with the visuo-spatial task when applied over the right PPC at an early stage (50 ms post-stimulus). The interference effect of single-pulse TMS in the present visuo-spatial processing is revealed by a processing cost for ipsilateral targets. These results are ... The right posterior parietal cortex (PPC) is implicated in visuospatial processing, as illustrated by patients with visuo-spatial neglect, but the precise time-course of its contribution is still an open question. In the present study we assessed whether single-pulse transcranial magnetic stimulation (TMS) can interfere with the performance of normal subjects in a standard visuo-spatial task. Participants had to perform a landmark task while TMS was applied over the right PPC, the homologue region in the left hemisphere or the right primary motor cortex. Stimulation was time-locked to the stimulus presentation with a stimulus onset asynchrony (SOA) varying between 50 and 200 ms. Our results indicate that TMS interfered mainly with the visuo-spatial task when applied over the right PPC at an early stage (50 ms post-stimulus). The interference effect of single-pulse TMS in the present visuo-spatial processing is revealed by a processing cost for ipsilateral targets. These results are in agreement with neuropsychological and brain imaging studies showing a right hemispheric dominance in visuo-spatial processing but add crucial information about the time-course of visuo-spatial processing within the right PPC.

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“…Therefore, careful construction is essential. Stimulating coils are available in a variety of shapes and sizes (Cohen et al 1990). Larger circular coils use more copper mass, thus having lower electrical resistance and higher heat capacity.…”

mentioning

confidence: 99%

“…Four-leaf magnetic coils (Roth et al 1994) and other, more complicated geometries and newer construction materials might in the future provide more focal stimulation coils. In the case of a circular coil the induced tissue current is maximal under the mean diameter and is near zero in the centre of the coil (¢gure 2) (Cohen et al 1990;Maccabee et al 1990;Tofts 1990;Roth et al 1991). In the case of the ¢gure-of-eight coil practically only neural structures under its centre (at the intersection of the two wings of the coil) are stimulated (¢gure 2) (Cohen et al 1990;Maccabee et al 1990;Tofts 1990;Roth et al 1991).…”

mentioning

confidence: 99%

Transcranial magnetic stimulation: studying the brain--behaviour relationship by induction of ‘virtual lesions’

Pascual‐Leone

Bartrés‐Faz²,

Keenan³

1999

Phil. Trans. R. Soc. Lond. B

389

191

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Transcranial magnetic stimulation (TMS) provides a non-invasive method of induction of a focal current in the brain and transient modulation of the function of the targeted cortex. Despite limited understanding about focality and mechanisms of action, TMS provides a unique opportunity of studying brain^behaviour relations in normal humans. TMS can enhance the results of other neuroimaging techniques by establishing the causal link between brain activity and task performance, and by exploring functional brain connectivity.

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Effects of coil design on delivery of focal magnetic stimulation. Technical considerations

Cited by 370 publications

References 10 publications

Role of the Primary Motor and Dorsal Premotor Cortices in the Anticipation of Forces during Object Lifting

Role of the Primary Motor and Dorsal Premotor Cortices in the Anticipation of Forces during Object Lifting

Event-related TMS over the right posterior parietal cortex induces ipsilateral visuo-spatial interference

Transcranial magnetic stimulation: studying the brain--behaviour relationship by induction of ‘virtual lesions’

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