An intra-neural microstimulation system for ultra-high field magnetic resonance imaging and magnetoencephalography

Glover, Paul; Watkins, Roger Holmes; O'Neill, George; Ackerley, Rochelle; Sánchez-Panchuelo, Rosa-Maria; McGlone, Francis; Brookes, Matthew J.; Wessberg, Johan; Francis, Susan T.

doi:10.1016/j.jneumeth.2017.07.016

Cited by 8 publications

(20 citation statements)

References 18 publications

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“…The datasets and experimental methods have been presented in ( O’Neill et al., 2019 ), and so a summary outline of the data and processing methods follows. In this subset of the data, 3 participants volunteered to undergo INMS of the left median nerve using an in-house microneurography and microstimulation kit ( Glover et al., 2017 ). When it had been confirmed that the spike discharge from a single mechanoreceptor in the left hand was detected by the electrode, a 1 s, 60 Hz spike train was delivered down the same electrode at 1 μA, with the current increased in 0.1 μA steps until a sensation was detected by the participant.…”

Section: Application Of the Probabilistic Atlas To Electrophysiologicmentioning

confidence: 99%

A probabilistic atlas of finger dominance in the primary somatosensory cortex

et al. 2020

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With the advent of ultra-high field (7T), high spatial resolution functional MRI (fMRI) has allowed the differentiation of the cortical representations of each of the digits at an individual-subject level in human primary somatosensory cortex (S1). Here we generate a probabilistic atlas of the contralateral SI representations of the digits of both the left and right hand in a group of 22 right-handed individuals. The atlas is generated in both volume and surface standardised spaces from somatotopic maps obtained by delivering vibrotactile stimulation to each distal phalangeal digit using a travelling wave paradigm. Metrics quantify the likelihood of a given position being assigned to a digit (full probability map) and the most probable digit for a given spatial location (maximum probability map). The atlas is validated using a leave-one-out cross validation procedure. Anatomical variance across the somatotopic map is also assessed to investigate whether the functional variability across subjects is coupled to structural differences. This probabilistic atlas quantifies the variability in digit representations in healthy subjects, finding some quantifiable separability between digits 2, 3 and 4, a complex overlapping relationship between digits 1 and 2, and little agreement of digit 5 across subjects. The atlas and constituent subject maps are available online for use as a reference in future neuroimaging studies.

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Section: Application Of the Probabilistic Atlas To Electrophysiologicmentioning

confidence: 99%

A probabilistic atlas of finger dominance in the primary somatosensory cortex

et al. 2020

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“…Here, we aimed to show the feasibility of combining single-unit INMS (using recently-developed stimulation hardware; Glover et al., 2017 ) with MEG, to probe whether we could reliably capture the spatial, spectral, and temporal properties of the cortical projections of individual single-unit mechanoreceptive afferents in human glabrous hand skin.…”

Section: Discussionmentioning

confidence: 99%

“…A high-impedance, insulated tungsten recording/stimulating electrode (15 mm length, shaft diameter 200 μm, tip diameter ∼5 μm; FHC, Bowdoin, ME) was then inserted percutaneously into the left median nerve, approximately 30 mm proximal from the wrist crease. A second uninsulated reference electrode was placed subcutaneously 50 mm away from the first and both were connected to an INMS system specifically designed to operate without generating measurable magnetic interference ( Glover et al., 2017 ). A diagram of the electrode setup is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…MEG provides unique spatiotemporal resolution, offering vastly improved temporal resolution over fMRI (which is limited by the haemodynamic lag of the BOLD effect, and it being an indirect measure of neural activity) and an improved spatial resolution compared to EEG (as magnetic fields are not distorted by the skull to the same extent as electric potentials). In this paper, we performed single-unit INMS, using a recently developed system designed for compatibility with MEG ( Glover et al., 2017 ). We aimed to demonstrate that this approach can localise the cortical response to single-unit INMS and capture the spatiotemporal dynamics of responses to simulation of individual mechanoreceptors, providing the feasibility of performing future studies to probe how the dynamics of different patterns of activity in these mechanoreceptors are represented cortically.…”

Section: Introductionmentioning

confidence: 99%

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Imaging human cortical responses to intraneural microstimulation using magnetoencephalography

et al. 2019

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The sensation of touch in the glabrous skin of the human hand is conveyed by thousands of fast-conducting mechanoreceptive afferents, which can be categorised into four distinct types. The spiking properties of these afferents in the periphery in response to varied tactile stimuli are well-characterised, but relatively little is known about the spatiotemporal properties of the neural representations of these different receptor types in the human cortex. Here, we use the novel methodological combination of single-unit intraneural microstimulation (INMS) with magnetoencephalography (MEG) to localise cortical representations of individual touch afferents in humans, by measuring the extracranial magnetic fields from neural currents. We found that by assessing the modulation of the beta (13–30 Hz) rhythm during single-unit INMS, significant changes in oscillatory amplitude occur in the contralateral primary somatosensory cortex within and across a group of fast adapting type I mechanoreceptive afferents, which corresponded well to the induced response from matched vibrotactile stimulation. Combining the spatiotemporal specificity of MEG with the selective single-unit stimulation of INMS enables the interrogation of the central representations of different aspects of tactile afferent signalling within the human cortices. The fundamental finding that single-unit INMS ERD responses are robust and consistent with natural somatosensory stimuli will permit us to more dynamically probe the central nervous system responses in humans, to address questions about the processing of touch from the different classes of mechanoreceptive afferents and the effects of varying the stimulus frequency and patterning.

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“…The first option requires considerable technical expertise and support. The second option, as noted previously (Glover et al , 2017), has associated higher costs and experimental flexibility is potentially constrained by closed-source software; which is required for commercial viability. These issues are not unique to microneurography and the neuroscience community has increasingly begun to adopt open-source hardware and software tools.…”

Section: Introductionmentioning

confidence: 99%