Light Scattering Changes Follow Evoked Potentials From Hippocampal Schaeffer Collateral Stimulation

Rector, David M.; Poe, Gina R.; Kristensen, Morten P.; Harper, Ronald M.

doi:10.1152/jn.1997.78.3.1707

Cited by 104 publications

(77 citation statements)

References 20 publications

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“…We only found indications of the fast signal in the phase in two out of 14 subjects, which is probably owing to the high noise in the phase signals. Based on studies conducted in single neurons (STEPNOSKI et al, 1991), in populations of neurons at the macroscopic level (RECTOR et al, 1997) and (invasively) in animals (MALONEK and GRINVALS, 1997), all authors of the cited literature assume that the fast signal originates from changes in light scattering. However, it cannot be excluded that the reported fast signals in human subjects are related to changes in light absorption.…”

Section: Discussionmentioning

confidence: 99%

Detection of fast neuronal signals in the motor cortex from functional near infrared spectroscopy measurements using independent component analysis

Morren

Wolf

Lemmerling

et al. 2004

Med. Biol. Eng. Comput.

112

102

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Section: Discussionmentioning

confidence: 99%

Detection of fast neuronal signals in the motor cortex from functional near infrared spectroscopy measurements using independent component analysis

Morren

Wolf

Lemmerling

et al. 2004

Med. Biol. Eng. Comput.

112

102

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“…The "early" response (related to the controversial issue of an initial dip, as discussed further on) has a latency of ∼200 milliseconds. In broader usage, however, IOS also comprises the fast scatter changes that have been reported to parallel the electrophysiologic response (Rector et al, 1997;Stepnoski et al, 1991). response based on the slow scatter changes.…”

Section: Exposed Cortexmentioning

confidence: 99%

“…Working in an exposed cortex model Rector et al (1995Rector et al ( , 1997 dedicated several studies to tracing the fast optical response, which is temporally correlated to the electrophysiologic response. In a recent article they differentiate four different responses based on their different temporal characteristics (Rector et al, 2001).…”

Section: Imaging the Human Brain With Lightmentioning

confidence: 99%

“…Gratton and Fabiani (2001) have published several reports that claim to noninvasively detect optical signals in parallel with electrophysiologic changes. As has been described earlier, such signals are well established for invasive approaches (Rector et al, 1997;Stepnoski et al, 1991). The question is whether the much smaller signal-to-noise ratio (SNR) in a noninvasive set-up will allow one to reproducibly trace these signals.…”

Section: Physiology Of the Signalmentioning

confidence: 99%

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Beyond the Visible—Imaging the Human Brain with Light

Obrig

Villringer

2003

J Cereb Blood Flow Metab

548

215

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Summary:Optical approaches to investigate cerebral function and metabolism have long been applied in invasive studies. From the neuron cultured in vitro to the exposed cortex in the human during neurosurgical procedures, high spatial resolution can be reached and several processes such as membrane potential, cell swelling, metabolism of mitochondrial chromophores, and vascular response can be monitored, depending on the respective preparation. The authors focus on an extension of optical methods to the noninvasive application in the human. Starting with the pioneering work of Jöbsis 25 years ago, nearinfrared spectroscopy (NIRS) has been used to investigate functional activation of the human cerebral cortex. Recently, several groups have started to use imaging systems that allow the generation of images of a larger area of the subject's head and, thereby, the production of maps of cortical oxygenation changes. Such images have a much lower spatial resolution compared with the invasively obtained optical images. The noninvasive NIRS images, however, can be obtained in undemanding set-ups that can be easily combined with other functional methods, in particular EEG. Moreover, NIRS is applicable to bedside use. The authors briefly review some of the abundant literature on intrinsic optical signals and the NIRS imaging studies of the past few years. The weaknesses and strengths of the approach are critically discussed. The authors conclude that NIRS imaging has two major advantages: it can address issues concerning neurovascular coupling in the human adult and can extend functional imaging approaches to the investigation of the diseased brain. Key Words: Near-infrared spectroscopy-Cerebral oxygenation-Vascular imagingNoninvasive.The first investigations into the functional anatomy of the human cerebral cortex were based on lesion studies. The role of specific cortical areas involved in a specific task was inferred by comparing a patient's dysfunction to the lesion seen at autopsy (Fig. 1A). Whereas initially only electrophysiologic techniques allowed noninvasive functional studies of the human brain, the advent of modern imaging techniques such as functional magnetic resonance imaging (fMRI) and positron emission tomography (PET) have increasingly dominated the field during the past decade. The great advantage is the spatial resolution, which for fMRI is steadily improving and may even allow the differentiation of different cortical layers.There is an increasing need, however, for a better understanding of the signal physiology, in particular of blood oxygenation level-dependent (BOLD) contrast, since the basic principles of the coupling between the neuronal and the vascular response to functional stimulation are still not fully understood (Villringer and Dirnagl, 1995).In the present article we focus on noninvasive imaging approaches in the human using light. Near-infrared spectroscopy (NIRS),* the technique on which such imaging approaches are based, has been covered in previous articles that reviewed its potential...

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“…Grinvald [34] reported a decrease in reflected light 200 ms after the onset of whisker stimulation. Rector [35] found a similar response synchronous to the electrical signal. Malonek [36] reported an increase in light intensity with a latency (i.e., the period between stimulation and response) of 200 ms.…”

Section: Neuronal Signalmentioning

confidence: 73%