The human electrocerebellogram (ECeG) recorded non-invasively using scalp electrodes

Key points The application of conventional cryogenic magnetoencephalography (MEG) to the study of cerebellar functions is highly limited because typical cryogenic sensor arrays are far away from the cerebellum and naturalistic movement is not allowed in the recording. A new generation of MEG using optically pumped magnetometers (OPMs) that can be worn on the head during movement has opened up an opportunity to image the cerebellar electrophysiological activity non‐invasively. We use OPMs to record human cerebellar MEG signals elicited by air‐puff stimulation to the eye. We demonstrate robust responses in the cerebellum. OPMs pave the way for studying the neurophysiology of the human cerebellum. Abstract We test the feasibility of an optically pumped magnetometer‐based magnetoencephalographic (OP‐MEG) system for the measurement of human cerebellar activity. This is to our knowledge the first study investigating the human cerebellar electrophysiology using optically pumped magnetometers. As a proof of principle, we use an air‐puff stimulus to the eyeball in order to elicit cerebellar activity that is well characterized in non‐human models. In three subjects, we observe an evoked component at approx. 50 ms post‐stimulus, followed by a second component at approx. 85–115 ms post‐stimulus. Source inversion localizes both components in the cerebellum, while control experiments exclude potential sources elsewhere. We also assess the induced oscillations, with time‐frequency decompositions, and identify additional sources in the occipital lobe, a region expected to be active in our paradigm, and in the neck muscles. Neither of these contributes to the stimulus‐evoked responses at 50–115 ms. We conclude that OP‐MEG technology offers a promising way to advance the understanding of the information processing mechanisms in the human cerebellum.

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“…; Todd et al . ). It is widely assumed that scalp EEG recordings for the cerebellum suffer from muscle artefacts (Muthukumaraswamy, ).…”

Section: Introductionmentioning

confidence: 99%

“…the finger-nose-finger test). The issue is not exclusive to MEG -to date, few studies with scalp cerebellar EEG have been reported (Muthukumaraswamy et al 2003;Lascano et al 2013;Todd et al 2018). It is widely assumed that scalp EEG recordings for the cerebellum suffer from muscle artefacts (Muthukumaraswamy, 2013).…”

Section: Introductionmentioning

confidence: 99%

Using optically pumped magnetometers to measure magnetoencephalographic signals in the human cerebellum

Lin

Tierney

Holmes

et al. 2019

The Journal of Physiology

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“…When superimposed over the mean response, the individual trial responses reveal a feature not seen with the mean. The background baseline spontaneous electrocerebellogram (Todd et al 2018) before stimulation appears to have a postresponse reduction or pause following stimulation that lasts~50 -60 ms and during which a lower amplitude slow wave can be seen. Figure 3 also shows the individual trial responses at subthreshold stimulus intensity indicating little or no response or poststimulus pause in electrocerebellogram.…”

Section: Resultsmentioning

confidence: 99%

“…For these reasons then, we developed a procedure to measure modulation of the putative vestibular CEPs during a well-defined and carefully controlled visual motion context where the apparent motion could be either congruent or incongruent with the vestibular stimulus. In addition to the above issues, the piloting work also indicated that a better recording site (in the sense of producing larger responses) was over the posterior fossa (Todd et al 2018), rather than PO7/8, a location that was also closer to the original 10 -20 cerebellum (CB) location as defined by Jasper (1958). A further aim of this study was to measure the properties of human evoked cerebellar activity during vestibular and visual stimulation.…”

Section: Introductionmentioning

confidence: 92%

Vestibular cerebellar evoked potentials in humans and their modulation during optokinetic stimulation

Todd

Govender

Colebatch

2018

Journal of Neurophysiology

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We recorded evoked potentials (EPs) from over the posterior fossa and in parallel ocular vestibular evoked myogenic potentials (OVEMPs) during visuo-vestibular stimulation in a sample of 7 male and 11 female human subjects. In 9 of the 18 subjects we were able to record EPs reliably in the form of an early biphasic positive-negative wave with latencies ~12 and 17 ms ipsilateral to head acceleration direction (P12-N17) and a slightly later, contralateral, biphasic positive-negative wave with latencies ~19 and 23 ms (P19-N23). The amplitudes of the responses varied widely between subjects. Both P12 and N23 EPs were modulated by the mode of visual stimulation, larger for vection (sense of movement) compared with optokinetic nystagmus and for congruent movement. We suggest that the EPs measured over the posterior fossa are a manifestation of climbing fiber responses of cerebellar cortical Purkinje cells, i.e., a form of vestibular cerebellar EP (VsCEP). The two subject groups with and without VsCEPs were distinguished by the magnitude of their OVEMPs and their subjective experience of vection. The modulation of VsCEPs by visual context may be a manifestation of cerebellar control of linear vestibular ocular reflex gain. NEW & NOTEWORTHY We report likely vestibular cerebellar evoked potentials (VsCEPs) produced by lateral head impulses recorded in intact humans over the posterior fossa. VsCEPs occurred as short-latency P12-N17 waves ipsilateral to the direction of head motion and as P19-N23 contralaterally and were present in half our subjects. Their properties suggest that the VsCEPs may be of a climbing-fiber origin. VsCEPs are related to the perception of motion and, possibly, control of linear vestibular ocular reflex gain.

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“…A recent study of Todd et al (2018) extended the 10-20 layout with extra electrodes below electrode Oz. They very interestingly found that these "cerebellar" electrodes picked up highfrequency oscillations (> 100 Hz) that were unique to these electrodes and not found on the occipital electrodes above nor the splenius muscle electrodes below.…”

Section: Coverage Of Meg Sensor Array or Eeg Coveragementioning

confidence: 99%

Can electro- and magnetoencephalography detect signals from the human cerebellum?

Andersen

Jerbi

Dalal

2019

Preprint

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The cerebellum plays a key role in the regulation of motor learning, coordination and timing, and has been implicated in sensory and cognitive processes as well. However, our current knowledge of its electrophysiological mechanisms comes primarily from direct recordings in animals, as investigations into cerebellar function in humans have instead predominantly relied on lesion, haemodynamic and metabolic imaging studies. While the latter provide fundamental insights into the contribution of the cerebellum to various cerebellar-cortical pathways mediating behaviour, they remain limited in terms of temporal and spectral resolution. In principle, this shortcoming could be overcome by monitoring the cerebellum’s electrophysiological signals. Non-invasive assessment of cerebellar electrophysiology in humans, however, is hampered by the limited spatial resolution of electroencephalography (EEG) and magnetoencephalography (MEG) in subcortical structures, i.e., deep sources. Furthermore, it has been argued that the anatomical configuration of the cerebellum leads to signal cancellation in MEG and EEG. Yet, claims that MEG and EEG are unable to detect cerebellar activity have been challenged by an increasing number of studies over the last decade. Here we address this controversy and survey reports in which neuromagnetic signals were successfully recorded from the human cerebellum. We argue that the detection of cerebellum activity non-invasively with MEG and EEG is indeed possible and can be enhanced with appropriate methods, in particular using connectivity analysis in source space. We provide illustrative examples of cerebellar activity detected with MEG and EEG. Furthermore, we propose practical guidelines to optimize the detection of cerebellar activity with MEG and EEG. Finally, we discuss MEG and EEG signal contamination that may lead to localizing spurious sources in the cerebellum and suggest ways of handling such artefacts. This review is to be read as a perspective review that highlights that it is indeed possible to measure cerebellum with MEG and EEG and encourages MEG and EEG researchers to do so. Its added value beyond highlighting and encouraging is that it offers useful advice for researchers aspiring to investigate the cerebellum with MEG and EEG.

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The human electrocerebellogram (ECeG) recorded non-invasively using scalp electrodes

Cited by 44 publications

References 27 publications

Using optically pumped magnetometers to measure magnetoencephalographic signals in the human cerebellum

Using optically pumped magnetometers to measure magnetoencephalographic signals in the human cerebellum

Vestibular cerebellar evoked potentials in humans and their modulation during optokinetic stimulation

Can electro- and magnetoencephalography detect signals from the human cerebellum?

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