Elevated endogenous GABA level correlates with decreased fMRI signals in the rat brain during acute inhibition of GABA transaminase

Chen, Zhengguang; Silva, Afonso C.; Yang, Jehoon; Shen, Jun

doi:10.1002/jnr.20364

Cited by 77 publications

(65 citation statements)

References 63 publications

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“…This is consistent with a recent study in rat somatosensory cortex (31), which measured the BOLD response after i.v. administration of vigabatrin, a drug that inhibits the action of GABA transaminase (GABA-T), which normally acts to break down GABA.…”

Section: Discussionsupporting

confidence: 93%

Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans

Muthukumaraswamy

Edden

Jones

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

524

490

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Functional imaging of the human brain is an increasingly important technique for clinical and cognitive neuroscience research, with functional MRI (fMRI) of the blood oxygen level-dependent (BOLD) response and electroencephalography or magnetoencephalography (MEG) recordings of neural oscillations being 2 of the most popular approaches. However, the neural and physiological mechanisms that generate these responses are only partially understood and sources of interparticipant variability in these measures are rarely investigated. Here, we test the hypothesis that the properties of these neuroimaging metrics are related to individual levels of cortical inhibition by combining magnetic resonance spectroscopy to quantify resting GABA concentration in the visual cortex, MEG to measure stimulus-induced visual gamma oscillations and fMRI to measure the BOLD response to a simple visual grating stimulus. Our results demonstrate that across individuals gamma oscillation frequency is positively correlated with resting GABA concentration in visual cortex (R ‫؍‬ 0.68; P < 0.02), BOLD magnitude is inversely correlated with resting GABA (R ‫؍‬ ؊0.64; P < 0.05) and that gamma oscillation frequency is strongly inversely correlated with the magnitude of the BOLD response (R ‫؍‬ ؊0.88; P < 0.001). Our results are therefore supportive of recent theories suggesting that these functional neuroimaging metrics are dependent on the excitation/inhibition balance in an individual's cortex and have important implications for the interpretation of functional imaging results, particularly when making between-group comparisons in clinical research.functional magnetic resonance imaging ͉ magnetic resonance spectroscopy ͉ magnetoencephalography ͉ oscillations T he high spatial resolution and noninvasive nature of blood oxygen level-dependent (BOLD) functional MRI (fMRI) (1) have led to it becoming one of the most popular tools for measuring brain function in human neuroscience. However, fMRI provides only an indirect measure of neural activity by measuring task-related changes in cerebral haemodynamics that are coupled by a complex and only partially understood mechanism to changes in underlying neural activity. Recent evidence suggests that oscillations in the gamma frequency range, loosely defined as approximately 30-100 Hz, are well correlated temporally, spatially, and functionally with haemodynamic changes in cortex, suggesting a close relationship with the BOLD response (2-6). There is also increasing evidence that the most plausible mechanism for the generation of gamma oscillations is a neuronal network containing a mixture of interconnected pyramidal cells and GABAergic inhibitory interneurons (7-10) with the balance of excitation-inhibition setting the peak gamma oscillation frequency of the network (11). Similarly, it has recently been argued that the magnitude of the BOLD response is also sensitive to this excitation-inhibition balance (12, 13).In the current study, we tested the hypothesis that the local level of inhibition in an i...

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Section: Discussionsupporting

confidence: 93%

Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans

Muthukumaraswamy

Edden

Jones

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

524

490

View full text Add to dashboard Cite

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“…In the question of the effects of GABA-ergic activation, we find no evidence in the literature that increased GABA release per se raises metabolism or blood flow; on the contrary, several recent studies suggest that GABA-ergic inhibition lowers blood flow in the target area [Chen et al, 2005;Roland and Friberg, 1988;Takano et al, 2004;Xi et al, 2002]. Early PET studies suggested that blood flow measures might fail to distinguish between increased GABA-ergic inhibition and increased glutamatergic excitation, as both require energy and both may benefit from increased blood flow [Ackermann et al, 1984].…”

Section: Discussioncontrasting

confidence: 92%

STN‐stimulation in Parkinson's disease restores striatal inhibition of thalamocortical projection

Geday

Østergaard

Johnsen

et al. 2007

Human Brain Mapping

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“…Chen and colleagues (Chen et al, 2005) demonstrated that elevated endogenous GABA levels, elicited using vigabatrin in rats, reduced stimulus induced BOLD responses to forepaw stimulation. In humans, several studies have looked at the correlation of GABA with positive BOLD responses.…”

Section: Bold and Mrs Studiesmentioning

confidence: 99%

The relationship between MEG and fMRI

et al. 2014

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In recent years functional neuroimaging techniques such as fMRI, MEG, EEG and PET have provided researchers with a wealth of information on human brain function. However none of these modalities can measure directly either the neuro-electrical or neuro-chemical processes that mediate brain function. This means that metrics directly reflecting brain 'activity' must be inferred from other metrics (e.g. magnetic fields (MEG) or haemodynamics (fMRI)). To overcome this limitation, many studies seek to combine multiple complementary modalities and an excellent example of this is the combination of MEG (which has high temporal resolution) with fMRI (which has high spatial resolution). However, the full potential of multi-modal approaches can only be truly realised in cases where the relationship between metrics is known. In this paper, we explore the relationship between measurements made using fMRI and MEG. We describe the origins of the two signals as well as their relationship to electrophysiology. We review multiple studies that have attempted to characterise the spatial relationship between fMRI and MEG, and we also describe studies that exploit the rich information content of MEG to explore differing relationships between MEG and fMRI across neural oscillatory frequency bands. Monitoring the brain at "rest" has become of significant recent interest to the neuroimaging community and we review recent evidence comparing MEG and fMRI metrics of functional connectivity. A brief discussion of the use of magnetic resonance spectroscopy (MRS) to probe the relationship between MEG/fMRI and neurochemistry is also given. Finally, we highlight future areas of interest and offer some recommendations for the parallel use of fMRI and MEG.

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Elevated endogenous GABA level correlates with decreased fMRI signals in the rat brain during acute inhibition of GABA transaminase

Cited by 77 publications

References 63 publications

Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans

Resting GABA concentration predicts peak gamma frequency and fMRI amplitude in response to visual stimulation in humans

STN‐stimulation in Parkinson's disease restores striatal inhibition of thalamocortical projection

The relationship between MEG and fMRI

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