Clinical Applications

Yamasaki, Takao; Inamizu, Saeko; Goto, Yoshinobu; Tobimatsu, Shozó

doi:10.1007/978-4-431-55729-6_8

Cited by 3 publications

(8 citation statements)

References 59 publications

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“…Exact low resolution brain electromagnetic tomography (eLORETA) analysis of the N170 revealed that the current density was significantly elevated over the occipito-temporal areas including V5/MT+ in response to both stimuli compared with RM baseline (Figure 5A ). These findings were consistent with those of minimum-norm estimate (MNE) of visual evoked magnetic fields (VEFs) ( 61 ). A direct comparison between OF and HO stimuli revealed no significant difference in the current density of the N170.…”

Section: Of-erps In Healthy Humanssupporting

confidence: 88%

Driving Ability in Alzheimer Disease Spectrum: Neural Basis, Assessment, and Potential Use of Optic Flow Event-Related Potentials

Yamasaki

Tobimatsu

2018

Front. Neurol.

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Driving requires multiple cognitive functions including visuospatial perception and recruits widespread brain networks. Recently, traffic accidents in dementia, particularly in Alzheimer disease spectrum (ADS), have increased and become an urgent social problem. Therefore, it is necessary to develop the objective and reliable biomarkers for driving ability in patients with ADS. Interestingly, even in the early stage of the disease, patients with ADS are characterized by the impairment of visuospatial function such as radial optic flow (OF) perception related to self-motion perception. For the last decade, we have studied the feasibility of event-related potentials (ERPs) in response to radial OF in ADS and proposed that OF-ERPs provided an additional information on the alteration of visuospatial perception in ADS (1, 2). Hence, we hypothesized that OF-ERPs can be a possible predictive biomarker of driving ability in ADS. In this review, the recent concept of neural substrates of driving in healthy humans are firstly outlined. Second, we mention the alterations of driving performance and its brain network in ADS. Third, the current status of assessment tools for driving ability is stated. Fourth, we describe ERP studies related to driving ability in ADS. Further, the neural basis of OF processing and OF-ERPs in healthy humans are mentioned. Finally, the application of OF-ERPs to ADS is described. The aim of this review was to introduce the potential use of OF-ERPs for assessment of driving ability in ADS.

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Section: Of-erps In Healthy Humanssupporting

confidence: 88%

Driving Ability in Alzheimer Disease Spectrum: Neural Basis, Assessment, and Potential Use of Optic Flow Event-Related Potentials

Yamasaki

Tobimatsu

2018

Front. Neurol.

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“…These stimuli elicit the occipito‐temporal N170 (a negative component with a peak latency around 170 ms), which is right lateralized for faces and left‐lateralized for words. The N170 for faces and words are thought to originate in the right and left fusiform gyri, respectively 8 …”

Section: Basic Technology Of Vepsmentioning

confidence: 99%

“…Coherent motion stimuli are useful for evaluating higher‐level dorsal stream function. The N2 component (at about 160‐200 ms) is generally considered to be a motion‐specific component and seems to be generated from the V5/MT 8 . The P2 peak (about 240 ms) depends on the type of motion.…”

Section: Basic Technology Of Vepsmentioning

confidence: 99%

“…The N2 component (at about 160-200 ms) is generally considered to be a motion-specific component and seems to be generated from the V5/MT. 8 The P2 peak (about 240 ms) depends on the type of motion. The P2 peak increases in magnitude with more-complex visual motion stimuli (expanding/contracting radial motion) because it represents a higher order of visual processing of biologically important stimuli.…”

Section: Assessment Of Higher-level Visual Pathwaysmentioning

confidence: 99%

“…for faces and words are thought to originate in the right and left fusiform gyri, respectively. 8 Coherent motion stimuli are useful for evaluating higher-level dorsal stream function. The N2 component (at about 160-200 ms) is generally considered to be a motion-specific component and seems to be generated from the V5/MT.…”

Section: Assessment Of Higher-level Visual Pathwaysmentioning

confidence: 99%

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Use of VEPs as electrodiagnostic biomarkers of mild cognitive impairment

Yamasaki

2020

Neurology & Clinical Neurosc

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Alzheimer's disease (AD) and its precursor, mild cognitive impairment (MCI), are characterized by early onset of visuospatial impairment along with memory impairment and disorientation. Based on these clinical features, I hypothesized that visual impairment might be a candidate biomarker for early electrodiagnosis of MCI. Therefore, I have been focusing on the application of visual evoked potentials (VEPs) as a non‐invasive, simple, and objective method for evaluating visual impairment in MCI patients. In this review, I first outline the concept of the human visual system. Second, I briefly mention the basic technology of VEPs. Then, I describe the previous VEP studies on AD and MCI. These VEP studies have reported that the lower‐level visual pathways are less likely to be involved in AD and MCI, whereas the higher‐level visual streams frequently show VEP abnormalities. Finally, I introduce my new VEP techniques for examining visual impairment in MCI. VEPs with multimodal visual stimuli (especially, optic flow motion) are useful for distinguishing MCI patients from non‐impaired individuals. It may also be feasible to discriminate the type of dementia responsible for MCI. From this review, I stress that VEPs are plausible biomarkers for the early electrodiagnosis of MCI.

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Helmholtz decomposition of the neuronal current for the ellipsoidal head model

Hashemzadeh

Fokas

2018

Inverse Problems

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In earlier work, the neuronal primary current was expressed via the Helmholtz decomposition in terms of its irrotational part characterised by a scalar function and its solenoidal part characterised by a vectorial function. Furthermore, it was shown that EEG data is affected only by the irrotational part of the current, whereas MEG data is affected by two scalar functions, namely the irrotational component and the radial part of the solenoidal vectorial function. Here, we focus on the numerical implementation of this approach on the three-layer ellipsoidal model. The parametrization of the unknown functions in terms of ellipsoidal harmonics implicitly regularizes the highly ill-posed associated inverse problems. However, despite the above parametrization of these two unknown functions in terms of ellipsoidal harmonics, the inversion matrices are highly ill-conditioned for both EEG and MEG. In order to bypass this problem, we propose an alternative approach to the inversion problem. This involves revisiting the general inversion formulas presented earlier by one of the authors and expressing them as surface integrals. By choosing a suitable parametrization for the relevant unknown functions, these surface integrals can be evaluated using a method for numerical quadrature over smooth, closed surfaces. The method uses local radial basis function interpolation for generating quadrature weights for any given node set. This gives rise to a stable linear system of equations suitable for inversion and reconstruction purposes. We illustrate the effectiveness of our approach by presenting simple reconstructions for both EEG and MEG in a setting where data are contaminated with Gaussian white noise of signal to noise ratio (SNR) of 20 dB.

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Clinical Applications

Cited by 3 publications

References 59 publications

Driving Ability in Alzheimer Disease Spectrum: Neural Basis, Assessment, and Potential Use of Optic Flow Event-Related Potentials

Driving Ability in Alzheimer Disease Spectrum: Neural Basis, Assessment, and Potential Use of Optic Flow Event-Related Potentials

Use of VEPs as electrodiagnostic biomarkers of mild cognitive impairment

Helmholtz decomposition of the neuronal current for the ellipsoidal head model

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