Measurement of Hemodynamics of Auditory Cortex Using Magnetoencephalography and Near Infrared Spectroscopy

Ohnishi, Michihiro; Kusakawa, Naoki; Shimizu, Masaki; Honda, Kiyoshi; Hayashi, Nobushige; Shimada, Yasuhiro; Fujimoto, Ichiro; Hirao, Konomu

doi:10.3109/00016489709126161

Cited by 16 publications

(21 citation statements)

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“…Only two adult case studies (5, 9) have been published on brain auditory cortex hemodynamics during the hearing function. On the basis of a magnetoencephalographic (MEG) and NIRS study, Ohnishi et al (9) found the auditory brain area to be about 25 mm under the scalp. In a dynamic multichannel near-infrared adult study, Hoshi and Tamura (5) (19 -23) We studied the auditory response in the temporal area of 19 newborns.…”

Section: Discussionmentioning

confidence: 99%

“…Changes in both HbO 2 and in Hb are measured from an arbitrary zero, and their sum is equal to total Hb, which is related to changes in CBV (13). Ohnishi et al (9) first measured the changes evoked in the hemodynamics of the auditory cortex with NIRS and magnetoencephalography in an adult subject. They found significant increases of the total Hb and deoxyHb in the brain region at a depth of 20 -30 mm corresponding to the auditory cortex of the MEG topogram.…”

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Brain Auditory Activation Measured by Near-Infrared Spectroscopy (NIRS) in Neonates

et al. 2001

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This study presents a new measure of the hemodynamic changes to an auditory stimulus in newborns. Nineteen newborns born at 28-41 wk and aged 1 to 49 d were studied in waking and/or sleeping state, for a median time of 4 min 40 s before, 2 min 40 s during, and 3 min 5 s after an acustic stimulus (tonal sweep of frequency increasing from 2 to 4 kHz, intensity 90 dB SPL) originating 5 cm from the external auditory meatus. The emitter and detector optodes were placed over the left or right temporal region, corresponding to T3 or T4 EEG electrodes. Near-infrared transmission spectroscopy (NIRS) through tissue is made possible by the transparency of biologic tissue to light in the near-infrared region (750 -1000 nm). The noninvasive nature of the technique and the portability of the device, combined with the relative transparency of the neonatal head, explain the early applications of the machine in neonatal intensive care units, to the observation of hemodynamic brain responses. Our study presents a method for applying NIRS to the testing of central auditory response in newborns by using an acustic stimulus, a tonal sweep with a frequency increasing from 2 to 4 KHz. The incident near-infrared light from the transmitting optode is scattered through the tissues, and the reflected light is read by a receiving optode. The amount of the light that a compound absorbs is dependent upon the wavelength of the incident light upon it, and is described by the spectrum of a single compound. Brain absorption of the light is due to the main cerebral chromophores, oxyhemoglobin (HbO 2 ), deoxyhemoglobin (Hb), and oxidized cytochrome oxidase (CtOx) and is determined by the oxygenation status of the compound. Through NIRS we measured the loss of the intensity due to absorption of the incident photons by these solutes; this loss or attenuation is usually measured in units of OD (OD) and can be calculated using the Beer-Lambert law. For an absorbing compound dissolved in a nonabsorbing medium, the attenuation (A) is proportional to the concentration of the compound in the solution (c), the specific extinction coefficient of the compound (␣) and the optical path length (

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Section: Discussionmentioning

confidence: 99%

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Brain Auditory Activation Measured by Near-Infrared Spectroscopy (NIRS) in Neonates

et al. 2001

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“…For instance, these factors could account for blood flow decreases instead of increases observed in the primary visual cortex (43). In spite of coarse spatial resolution, near-infrared spectroscopy seems an interesting, noninvasive, complementary procedure to study physiological cerebral vascular responses of infants or neonates to stimulation of sensory cortical areas (272).…”

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confidence: 99%

Renewal of the Neurophysiology of Language: Functional Neuroimaging

Démonet¹,

Thierry²,

Cardebat³

2005

Physiological Reviews

367

207

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Functional neuroimaging methods have reached maturity. It is now possible to start to build the foundations of a physiology of language. The remarkable number of neuroimaging studies performed so far illustrates the potential of this approach, which complements the classical knowledge accumulated on aphasia. Here we attempt to characterize the impact of the functional neuroimaging revolution on our understanding of language. Although today considered as neuroimaging techniques, we refer less to electroencephalography and magnetoencephalography studies than to positron emission tomography and functional magnetic resonance imaging studies, which deal more directly with the question of localization and functional neuroanatomy. This review is structured in three parts. 1) Because of their rapid evolution, we address technical and methodological issues to provide an overview of current procedures and sketch out future perspectives. 2) We review a set of significant results acquired in normal adults (the core of functional imaging studies) to provide an overview of language mechanisms in the “standard” brain. Single-word processing is considered in relation to input modalities (visual and auditory input), output modalities (speech and written output), and the involvement of “central” semantic processes before sentence processing and nonstandard language (illiteracy, multilingualism, and sensory deficits) are addressed. 3) We address the influence of plasticity on physiological functions in relation to its main contexts of appearance, i.e., development and brain lesions, to show how functional imaging can allow fine-grained approaches to adaptation, the fundamental property of the brain. In closing, we consider future developments for language research using functional imaging.

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“…NIRS topography provides only 2D brain surface mapping with limited spatial resolution but offers the advantage of high temporal resolution and resistance to motion artifact, enabling the measurement to be performed in a recumbent or sitting position. This method has been shown to reflect cerebral cortical activation related to motor activity, 12,13 mental tasks, 14 visual and auditory stimulation, 15,16 speech, 17 and epileptic seizures. 18 Until now, no complete study of poststroke motor recovery with NIRS has been reported.…”

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Near-Infrared Spectroscopic Topography as a Tool to Monitor Motor Reorganization After Hemiparetic Stroke

Kato

Izumiyama

Koizumi

et al. 2002

Stroke

108

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Background and Purpose-Motor functional recovery from stroke can occur, but the mechanisms underlying this restorative process remain to be elucidated. We used near-infrared spectroscopic (NIRS) topography in comparison with functional MRI (fMRI) to evaluate the compensatory motor activation of cortical regions in patients who recovered from hemiparesis after cortical cerebral infarction. Methods-We examined 6 right-handed patients who suffered cerebral infarction of the middle cerebral artery territory with minimal or mild residual contralateral hemiparesis (4 men and 2 women, 59 to 79 years old, all had left hemiparesis). Both fMRI and NIRS were studied during a hand movement task at chronic stages. Five right-handed, normal subjects (3 men and 2 women, 44 to 81 years old) served as controls. Results-fMRI and NIRS detected very similar cerebral cortical activation, although NIRS detected only superficial activation. The spatial resolution of NIRS was less than that of fMRI, but NIRS provided a dynamic profile of activation. Normal subjects activated predominantly the contralateral primary sensorimotor cortex and supplementary motor areas during each hand movement. All the stroke patients exhibited the normal activation pattern during normal hand movement. On affected hand movement, the stroke patients showed extended activation not only in the contralateral motor cortex but also in the ipsilateral motor cortex (primary motor cortex and supplementary motor areas). Conclusions-Both fMRI and NIRS studies provided evidence for the contribution of ipsilateral motor cortical compensation or reorganization to the recovery from poststroke hemiparesis. The result demonstrated that NIRS was a unique tool to monitor poststroke alterations in cortical motor functions.

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Measurement of Hemodynamics of Auditory Cortex Using Magnetoencephalography and Near Infrared Spectroscopy

Cited by 16 publications

References 0 publications

Brain Auditory Activation Measured by Near-Infrared Spectroscopy (NIRS) in Neonates

Brain Auditory Activation Measured by Near-Infrared Spectroscopy (NIRS) in Neonates

Renewal of the Neurophysiology of Language: Functional Neuroimaging

Near-Infrared Spectroscopic Topography as a Tool to Monitor Motor Reorganization After Hemiparetic Stroke

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