The effect on corticospinal volleys of reversing the direction of current induced in the motor cortex by transcranial magnetic stimulation

Lazzaro, Vincenzo Di; Oliviero, Antonio; Saturno, E.; Pilato, Fabio; Insola, Angelo; Mazzone, Paolo; Profice, Paolo; Tonali, P.; Rothwell, John C.

doi:10.1007/s002210100722

Cited by 222 publications

(228 citation statements)

References 6 publications

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“…This experiment was performed in subject 6. As reported previously (Di Lazzaro et al 2001;Sakai et al 1997), a single AP test pulse recruited a small D wave and an I3 wave. In addition, there was a small I4 wave that had a slightly longer latency (0.3 ms) than that seen after PA stimulation and a very small wave in the latency range of the I5 wave (Fig.…”

Section: Control Experimentssupporting

confidence: 75%

Origin of Facilitation of Motor-Evoked Potentials After Paired Magnetic Stimulation: Direct Recording of Epidural Activity in Conscious Humans

Lazzaro¹,

Pilato²,

Oliviero³

et al. 2006

Journal of Neurophysiology

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. Origin of facilitation of motor-evoked potentials after paired magnetic stimulation: direct recording of epidural activity in conscious humans. J Neurophysiol 96: 1765-1771, 2006. First published June 7, 2006 doi:10.1152/jn.00360.2006. A magnetic transcranial conditioning stimulus given over the motor cortex at intensities below active threshold for obtaining motor-evoked potentials (MEPs) facilitates EMG responses evoked at rest in hand muscles by a suprathreshold magnetic stimulus given 10 -25 ms later. This is known as intracortical facilitation (ICF). We recorded descending volleys produced by single and paired magnetic motor cortex stimulation through high cervical epidural electrodes implanted for pain relief in six conscious patients. At interstimulus intervals (ISIs) of 10 and 15 ms, although MEP was facilitated, there was no change in the amplitude or number of descending volleys. An additional I wave sometimes was observed at 25 ms ISI. In one subject, we also evaluated the effects of reversing the direction of the induced current in the brain. At 10 ms ISI, the facilitation of the MEPs disappeared and was replaced by slight suppression; at 2 ms ISI, there was a pronounced facilitation of epidural volleys. Subsequent experiments on healthy subjects showed that a conditioning stimulus capable of producing ICF of MEPs had no effect on the EMG response evoked by transmastoidal electrical stimulation of corticospinal tract. We conclude that ICF occurs because either 1) the conditioning stimulus has a (thus far undetected) effect on spinal cord excitability that increases its response to the same amplitude test volley or 2) that it can alter the composition (but not the amplitude) of the descending volleys set up by the test stimulus such that a larger proportion of the activity is destined for the target muscle. et al. (1993) studied the interaction between pairs of transcranial magnetic stimuli delivered through a single coil to the motor cortex. They found that a small, subthreshold conditioning stimulus could suppress the response to a later suprathreshold test stimulus if the interval between the stimuli [interstimulus interval (ISI)] was 5 ms or less. In contrast, there was facilitation when the ISI was from 10 to 25 ms. Because the intensity of the conditioning stimulus was below threshold both for producing a direct motor response and any effects on spinal H-reflexes, they suggested that the interaction occurred between circuits activated within the cerebral cortex. Direct evidence of intracortical origin of the short latency inhibitory component was obtained by recording from electrodes inserted into the cervical epidural space of conscious patients (Di Lazzaro et al. 1998;Nakamura et al. 1997). These showed that a conditioning shock could reduce the amplitude of corticospinal volleys evoked by the test stimulus, confirming that the interaction between stimuli did occur within the motor cortex. The periods of inhibition and facilitation are now termed short interval intracortical inhibition (SI...

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Section: Control Experimentssupporting

confidence: 75%

Origin of Facilitation of Motor-Evoked Potentials After Paired Magnetic Stimulation: Direct Recording of Epidural Activity in Conscious Humans

Lazzaro¹,

Pilato²,

Oliviero³

et al. 2006

Journal of Neurophysiology

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182

134

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“…Several studies have discussed this issue. Although a number of studies have shown that MEP amplitude was altered by the use of various current directions (Di Lazzaro et al 2001;Sakai et al 1997;Werhahn et al 1994), Chen et al (2003) and Ni et al (2009) showed that the current direction of the CS did not affect the degree of IHI. If the contralateral corticospinal output affects the degree of IHI, different degrees of IHI would be detected during the use of various CS current directions.…”

Section: Discussionmentioning

confidence: 99%

Changes in interhemispheric inhibition from active to resting primary motor cortex during a fine-motor manipulation task

Morishita

Uehara

Funase

2012

Journal of Neurophysiology

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Morishita T, Uehara K, Funase K. Changes in interhemispheric inhibition from active to resting primary motor cortex during a fine-motor manipulation task. J Neurophysiol 107: 3086 -3094, 2012. First published March 14, 2012 doi:10.1152/jn.00888.2011.-The effect of performance of a sensorimotor task on the interhemispheric inhibition (IHI) induced from the active primary motor cortex (M1) to the resting M1 was examined in 10 right-handed subjects. Transcranial magnetic stimulation (TMS) was performed to produce motor evoked potentials (MEP) in the resting right (Rt)-first dorsal interosseous (FDI). For the paired-TMS paradigm, a conditioning stimulus (CS) was delivered to the Rt-M1, and its intensity was adjusted from 0.6 to 1.4 times the resting motor threshold of the MEP in the left (Lt)-FDI in 0.2 steps. The test stimulus was delivered to the Lt-M1, and its intensity was adjusted to evoke similar MEP amplitudes in the Rt-FDI among the task conditions. The interstimulus interval was fixed at 10 ms. As a sensorimotor task, a fine-motor manipulation (FM) task (using chopsticks to pick up, transport, and release glass balls) was adopted. In addition, an isometric abduction (IA) task was also performed as a control task. These tasks were carried out with the left hand. The IHI from the active to the resting M1 observed during the FM task was markedly increased compared with that induced during the IA task, and this effect was not dependent on the MEP amplitude evoked in the active Lt-FDI by the CS. The present findings suggest that the increased IHI from the active to the resting M1 observed during the FM task was linked to reductions in the activity of the ipsilateral intracortical inhibitory circuit, as we reported previously.

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“…We do not know the reason for the broad distribution of optimal orientation for the lowest stimulus thresholds in our participants. Changing the direction of the induced current affects the shape of the motor evoked potential (Di Lazzaro et al, 2001;Dubach et al, 2004;Takahashi et al, 2005;Trompetto et al, 1999) and the duration of the cortical silent period (Orth and Rothwell, 2004) as if different neural structures or circuits respond optimally at different orientations of the coil. Variations in the microscopic anatomy across subjects may explain this variability of the optimal coil orientation.…”

Section: Discussionmentioning

confidence: 99%

Inter-individual variability in optimal current direction for transcranial magnetic stimulation of the motor cortex

Balslev

Braet

McAllister

et al. 2007

Journal of Neuroscience Methods

108

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We evaluated inter-individual variability in optimal current direction for biphasic transcranial magnetic stimulation (TMS) of the motor cortex. Motor threshold for first dorsal interosseus was detected visually at eight coil orientations in 45• increments. Each participant (n = 13) completed two experimental sessions. One participant with low test-retest correlation (Pearson's r < 0.5) was excluded. In four subjects, visual detection of motor threshold was compared to EMG detection; motor thresholds were very similar and highly correlated (0.94-0.99).Similar with previous studies, stimulation in the majority of participants was most effective when the first current pulse flowed towards posterolateral in the brain. However, in four participants, the optimal coil orientation deviated from this pattern. A principal component analysis using all eight orientations suggests that in our sample the optimal orientation of current direction was normally distributed around the postero-lateral orientation with a range of 63• (S.D. = 13.70 • ). Whenever the intensity of stimulation at the target site is calculated as a percentage from the motor threshold, in order to minimize intensity and side-effects it may be worthwhile to check whether rotating the coil 45• from the traditional posterior-lateral orientation decreases motor threshold.

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The effect on corticospinal volleys of reversing the direction of current induced in the motor cortex by transcranial magnetic stimulation

Cited by 222 publications

References 6 publications

Origin of Facilitation of Motor-Evoked Potentials After Paired Magnetic Stimulation: Direct Recording of Epidural Activity in Conscious Humans

Origin of Facilitation of Motor-Evoked Potentials After Paired Magnetic Stimulation: Direct Recording of Epidural Activity in Conscious Humans

Changes in interhemispheric inhibition from active to resting primary motor cortex during a fine-motor manipulation task

Inter-individual variability in optimal current direction for transcranial magnetic stimulation of the motor cortex

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