Uneven interhemispheric connections between left and right primary sensori‐motor areas

Terada, Kiyohito; Umeoka, Shuichi; Usui, Naotaka; Baba, Koichi; Usui, Keiko; Fujitani, Shigeru; Matsuda, Kazumi; Tottori, Takayasu; Nakamura, Fumihiro; Inoue, Yushi

doi:10.1002/hbm.21189

Cited by 33 publications

(21 citation statements)

References 37 publications

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“…A small positive deflection preceding N1, namely, the onset of N1, is termed P1 by some authors since this could reflect the very first volley to the target cortex [21, 22]. As many CCEP studies have been reported in the last decade, it is now known that CCEP waveform has some variations.…”

Section: Ccep Methodologymentioning

confidence: 99%

Single pulse electrical stimulation to probe functional and pathological connectivity in epilepsy

Matsumoto

Kunieda

Nair

2017

Seizure

151

160

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In the last decade, single pulse electrical stimulation (SPES) has been used as an investigational tool in the field of epilepsy surgery. Direct cortical stimulation applied at a frequency of ∼1 Hz can probe cortico-cortical connections by averaging electrocorticogram time-lock to the stimuli (2 x 20–30 trials). These evoked potentials that emanate from adjacent and remote cortices have been termed cortico-cortical evoked potentials (CCEPs). Although limited to patients undergoing invasive presurgical evaluations with intracranial electrodes, CCEP provides a novel way to explore inter-areal connectivity in vivo in the living human brain to probe functional brain networks such as language and cognitive motor networks. In addition to its impact on systems neuroscience, this method, in combination with 50 Hz electrical cortical stimulation, could contribute clinically to map the functional brain systems by tracking the cortico-cortical connections among the functional cortical regions in each individual patient. This approach may help identify the normal cortico-cortical network within pathology as well as reveal connections that might arise from neural plasticity. Because of its high practicality, it has been recently applied for intraoperative monitoring of the functional brain networks for patients with brain tumor. With regard to epilepsy, SPES has been used for the two major purposes, one to probe cortical excitability of the focus, namely, epileptogenicity, and the other to probe seizure networks. Both early (i.e., CCEP) and delayed responses, and probably their high frequency oscillation counterparts, are regarded as a surrogate marker of epileptogenicity. With regards to its impact on the human brain connectivity map, worldwide collaboration is warranted to establish the standardized CCEP connectivity map as a solid reference for non-invasive connectome researches.

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Section: Ccep Methodologymentioning

confidence: 99%

Single pulse electrical stimulation to probe functional and pathological connectivity in epilepsy

Matsumoto

Kunieda

Nair

2017

Seizure

151

160

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“…We find that using our estimates 252 of volume-weighted average of axon diameter in the numerical simulation leads to callosal 253 delays around 7-25 ms. This range is close to that found in electrophysiological studies 254 (92)(93)(94)(95)(96), and using response-time differences (33,97). For the following sections, we will 255 use an axon diameter of 1.72, 2.81 and 1.3 , for the occipital, motor and frontal tracts, 256…”

Section: Simulation and Choice Of Parameters 197mentioning

confidence: 66%

“…The determinants of conduction velocity of action potential propagation along a myelinated 95 axon have been previously described and modelled. Rushton (18) was the first to describe 96 the dependence of the conduction velocity of a myelinated axon on its geometry.…”

Section: Dependence Of Conduction Velocity On Axon Geometry 94mentioning

confidence: 99%

Modelling conduction delays in the corpus callosum using MRI-measured g-ratio

Berman

Filo

Mezer

2018

Preprint

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Conduction of action potentials along myelinated axons is affected by their structural features, such as the axonal g-ratio, the ratio between the inner and outer diameters of the myelin sheath surrounding the axon. The effect of g-ratio variance on conduction properties has been quantitatively evaluated using single-axon models. It has recently become possible to estimate a g-ratio weighted measurement in vivo using quantitative MRI. Nevertheless, it is still unclear whether the variance in the g-ratio in the healthy human brain leads to significant differences in conduction velocity. In this work we tested whether the g-ratio MRI measurement can be used to predict conduction delays in the corpus callosum.We present a novel framework in which the structural properties of fibers (i.e. length and g-ratio, measured using MRI), are incorporated in a biophysical model of axon conduction, to predict conduction delays of long-range white matter fibers. We applied this framework to the corpus callosum, and found conduction delay estimates that are compatible with previously estimated values of conduction delays. We account for the variance in the velocity given the axon diameter distribution in the splenium, mid-body and genu, to further compare the fibers within the corpus callosum.Conduction delays have been suggested to increase with age. Therefore, we investigated whether there are differences in the g-ratio and the fiber length between young and old adults, and whether this leads to a difference in conduction speed and delays. We found small but significant differences between the predicted delays of the two groups in the motor fibers of the corpus callosum. We also found that the motor fibers of the corpus callosum have the fastest conduction estimates. Using the axon diameter distributions, we found that the occipital fibers have the slowest estimations, while the frontal and motor fiber tracts have similar estimates.Our study provides a framework for predicting conduction latencies in vivo. The framework could have major implications for future studies of white matter diseases and large range network computations. Our results highlight the need for improving additional in vivo measurements of white matter microstructure.

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“…This well-established method allows one to unravel functional connectivity in the cortex [7][8][9][10][11][12] or subcortical regions [13], and recent studies used ECoG-based SPES in humans to investigate CCEPassociated changes in the spectral domain [14,15]. For reviews on studies investigating cortical connectivity by means of CCEPs see [16,17].…”

Section: μEcog Electrode Array Implant and Implantation Proceduresmentioning

confidence: 99%

Closed-loop interaction with the cerebral cortex using a novel micro-ECoG-based implant: the impact of beta vs. gamma stimulation frequencies on cortico-cortical spectral responses

Gkogkidis

Wang

Schubert

et al. 2017

Brain-Computer Interfaces

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(2017) Closed-loop interaction with the cerebral cortex using a novel micro-ECoG-based implant: the impact of beta vs. gamma stimulation frequencies on cortico-cortical spectral responses, 4:4,[214][215][216][217][218][219][220][221][222][223][224] Cemt, experimental surgery, medical Center, faculty of medicine, university of freiburg, freiburg, Germany ABSTRACT Medical brain implants for closed-loop interaction with the cerebral cortex promise new treatment options for brain disorders, and thus great efforts are being made to develop devices for long-term application. Closed-loop interaction can be implemented using electrophysiological recording techniques, and can be used to modulate local cortical activity or long-range functional connectivity. In a case study performed in sheep chronically implanted with a novel micro-electrocorticographybased device, we show that (1) open-loop single-pulse electrical stimulation (SPES) elicited the well-known cortico-cortical evoked potentials (CCEPs), and (2) closed-loop repetitive-pulse electrical stimulation (RPES) elicited specific cortico-cortical spectral responses (CCSRs). CCSRs were spatially focalized in the gamma band, compared with beta band independent of RPES frequency. The topography of CCSRs was different compared with CCEPs, suggesting that CCEPs and CCSRs capture different aspects of cortico-cortical connectivity. We propose that CCSRs provide new useful measures of functional connectivity, and that in particular gamma-band CCSRs may be an optimal choice if spatially precise closed-loop interaction is desired. However, the parameter space of microelectrocorticography stimulation patterns and associated changes in μECoG frequency bands needs to be further explored and many questions remain before closed-loop brain implants can be used in clinical applications.

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Uneven interhemispheric connections between left and right primary sensori‐motor areas

Cited by 33 publications

References 37 publications

Single pulse electrical stimulation to probe functional and pathological connectivity in epilepsy

Single pulse electrical stimulation to probe functional and pathological connectivity in epilepsy

Modelling conduction delays in the corpus callosum using MRI-measured g-ratio

Closed-loop interaction with the cerebral cortex using a novel micro-ECoG-based implant: the impact of beta vs. gamma stimulation frequencies on cortico-cortical spectral responses

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