Cerebellar transcranial magnetic stimulation: The role of coil type from distinct manufacturers

Spampinato, Danny; Ibáñez, Jaime; Spanoudakis, Manos; Hammond, Paul; Rothwell, John C.

doi:10.1016/j.brs.2019.09.005

Cited by 34 publications

(27 citation statements)

References 28 publications

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“…The MEPs amplitudes from both unconditioned and conditioned MEPs were considered for analysis. As in previous studies [ [31] , [32] , [33] , [34] ], we excluded extreme MEP amplitudes in which responses were more than 1.5 times above the third quartile or below the first quartile of the interquartile range. Trials were also excluded if ongoing muscle activity was detected (EMG signal >50 μV within 100 ms before TMS pulse) [ 34 ].…”

Section: Methodsmentioning

confidence: 99%

Two forms of short-interval intracortical inhibition in human motor cortex

Fong¹,

Spampinato²,

Rocchi³

et al. 2021

Brain Stimulation

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Background: Pulses of transcranial magnetic stimulation (TMS) with a predominantly anterior-posterior (AP) or posterior-anterior (PA) current direction over the primary motor cortex appear to activate distinct excitatory inputs to corticospinal neurons. In contrast, very few reports have examined whether the inhibitory neurons responsible for short-interval intracortical inhibition (SICI) are sensitive to TMS current direction. Objectives: To investigate whether SICI evaluated with AP and PA conditioning stimuli (CS PA and CS AP ) activate different inhibitory pathways. SICI was always assessed using a PA-oriented test stimulus (TS PA ). Methods: Using two superimposed TMS coils, CS PA and CS AP were applied at interstimulus intervals (ISI) of 1e5 ms before a TS PA , and at a range of different intensities. Using a triple stimulation design, we then tested whether SICI at ISI of 3 ms using opposite directions of CS (SICI CSPA3 and SICI CSAP3 ) interacted differently with three other forms of inhibition, including SICI at ISI of 2 ms (SICI CSPA2 ), cerebellum-motor cortex inhibition (CBI 5 ms) and short-latency afferent inhibition (SAI 22 ms). Finally, we compared the effect of tonic and phasic voluntary contraction on SICI CSPA3 and SICI CSAP3 . Results: CS AP produced little SICI at ISIs ¼ 1 and 2 ms. However, at ISI ¼ 3 ms, both CS AP and CS PA were equally effective at the same percent of maximum stimulator output. Despite this apparent similarity, combining SICI CSPA3 or SICI CSAP3 with other forms of inhibition led to quite different results: SICI CSPA3 interacted in complex ways with CBI, SAI and SICI CSPA2 , whereas the effect of SICI CSAP3 appeared to be quite independent of them. Although SICI CSPA and SICI CSAP were both reduced by the same amount during voluntary tonic contraction compared with rest, in a simple reaction time task SICI CSAP was disinhibited much earlier following the imperative signal than SICI CSPA . Conclusions: SICI CSPA appears to activate a different inhibitory pathway to that activated by SICI CSAP . The difference is behaviourally relevant since the pathways are controlled differently during volitional contraction. The results may explain some previous pathological data and open the possibility of testing whether these pathways are differentially recruited in a range of tasks.

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Section: Methodsmentioning

confidence: 99%

Two forms of short-interval intracortical inhibition in human motor cortex

Fong¹,

Spampinato²,

Rocchi³

et al. 2021

Brain Stimulation

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“…The coil was positioned in this manner to ensure optimal stimulation of the cerebellum without directly activating the spinal cord [9,40]. For all measures requiring cerebellar stimulation, we set the TMS intensity to 60% of maximum stimulator output (MSO), as this value does not active the brainstem and is easily tolerated by participants [16,21].…”

Section: Cerebellar-m1 Connectivity (Cbi)mentioning

confidence: 99%

“…This is most likely due to the substantial interindividual variability and lack of neural predictors in response to brain stimulation. In part, this is explained by the limited range in which stimulation can target the cerebellum [21], including where stimulation should be applied (e.g. location of figure-eight TMS coil) and which montage should be selected (e.g.…”

Section: Introductionmentioning

confidence: 99%

Frequency-dependent modulation of cerebellar excitability during the application of non-invasive alternating current stimulation

et al. 2021

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Background: it is well-known that the cerebellum is critical for the integrity of motor and cognitive actions. Applying non-invasive brain stimulation techniques over this region results in neurophysiological and behavioural changes, which have been associated with the modulation of cerebellar-cerebral cortex connectivity. Here, we investigated whether online application of cerebellar transcranial alternating current stimulation (tACS) results in changes to this pathway. Methods: thirteen healthy individuals participated in two sessions of cerebellar tACS delivered at different frequencies (5Hz and 50Hz). We used transcranial magnetic stimulation to measure cerebellarmotor cortex (M1) inhibition (CBI), short-intracortical inhibition (SICI) and short-afferent inhibition (SAI) before, during and after the application of tACS. Results: we found that CBI was specifically strengthened during the application of 5Hz cerebellar tACS. No changes were detected immediately following the application of 5Hz stimulation, nor at any time point with 50Hz stimulation. We also found no changes to M1 intracortical circuits (i.e. SICI) or sensorimotor interaction (i.e. SAI), indicating that the effects of 5Hz tACS over the cerebellum are site-specific. Conclusions: cerebellar tACS can modulate cerebellar excitability in a time-and frequency-dependent manner. Additionally, cerebellar tACS does not appear to induce any long-lasting effects (i.e. plasticity), suggesting that stimulation enhances oscillations within the cerebellum only throughout the stimulation period. As such, cerebellar tACS may have significant implications for diseases manifesting with abnormal cerebellar oscillatory activity and also for future behavioural studies.

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“…Across all studies, we found nine individuals who displayed a BaMT response under 75% MSO (mean cerebellar conditioning intensity, 68.57 6 0.75; Table 1). To assess cerebellar-M1 connectivity (CBI), the double-cone coil was then placed over the right cerebellar cortex 3 cm lateral to the inion, with the stimulator current directed downward (Hardwick et al, 2014;Ginatempo et al, 2019;Spampinato et al, 2020). Moreover, the TS over left M1 was delivered using a 70-mm-diameter figure-of-eight coil, and the intensity was set to a stimulator output that elicited ;1 mV MEP response.…”

Section: Participantsmentioning

confidence: 99%

Cerebellar–Motor Cortex Connectivity: One or Two Different Networks?

Spampinato¹,

Celnik²,

Rothwell³

2020

J. Neurosci.

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Anterior-posterior (AP) and posterior-anterior (PA) pulses of transcranial magnetic stimulation (TMS) over the primary motor cortex (M1) appear to activate distinct interneuron networks that contribute differently to two varieties of physiological plasticity and motor behaviors (Hamada et al., 2014). The AP network is thought to be more sensitive to online manipulation of cerebellar (CB) activity using transcranial direct current stimulation. Here we probed CB-M1 interactions using cerebellar brain inhibition (CBI) in young healthy female and male individuals. TMS over the cerebellum produced maximal CBI of PA-evoked EMG responses at an interstimulus interval of 5 ms (PA-CBI), whereas the maximum effect on AP responses was at 7 ms (AP-CBI), suggesting that CB-M1 pathways with different conduction times interact with AP and PA networks. In addition, paired associative stimulation using ulnar nerve stimulation and PA TMS pulses over M1, a protocol used in human studies to induce cortical plasticity, reduced PA-CBI but not AP-CBI, indicating that cortical networks process cerebellar inputs in distinct ways. Finally, PA-CBI and AP-CBI were differentially modulated after performing two different types of motor learning tasks that are known to process cerebellar input in different ways. The data presented here are compatible with the idea that applying different TMS currents to the cerebral cortex may reveal cerebellar inputs to both the premotor cortex and M1. Overall, these results suggest that there are two independent CB-M1 networks that contribute uniquely to different motor behaviors. Significance StatementConnections between the cerebellum and primary motor cortex (M1) are essential for performing daily life activities, as damage to these pathways can result in faulty movements. Therefore, developing and understanding novel approaches to probe this pathway are critical to advancing our understanding of the pathophysiology of diseases involving the cerebellum. Here, we show evidence for two distinct cerebellar-cerebral interactions using cerebellar stimulation in combination with directional transcranial magnetic stimulation (TMS) over M1. These distinct cerebellar-cerebral interactions respond differently to physiological plasticity and to distinct motor learning tasks, which suggests they represent separate cerebellar inputs to the premotor cortex and M1. Overall, we show that directional TMS can probe two distinct cerebellar-cerebral pathways that likely contribute to independent processes of learning.

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Cerebellar transcranial magnetic stimulation: The role of coil type from distinct manufacturers

Cited by 34 publications

References 28 publications

Two forms of short-interval intracortical inhibition in human motor cortex

Two forms of short-interval intracortical inhibition in human motor cortex

Frequency-dependent modulation of cerebellar excitability during the application of non-invasive alternating current stimulation

Cerebellar–Motor Cortex Connectivity: One or Two Different Networks?

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