High-Resolution Neurometabolic Coupling in the Lateral Geniculate Nucleus

Li, Baowang; Freeman, Ray

doi:10.1523/jneurosci.1505-07.2007

Cited by 39 publications

(58 citation statements)

References 45 publications

(96 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This contradicts a sensory enhancement account in which attention acts to improve the discriminability of sensory signals. Compressive (or, equivalently, expansive if reported as the dependence of hemodynamic activity on electrophysiological activity) (Devor et al 2003;Li and Freeman 2007;Offenhauser et al 2005;Sheth et al 2004), linear (Arthurs et al 2000Ogawa et al 2000;Ngai et al 1999;Smith et al 2002). and threshold-linear relationships (Logothetis et al 2001;Schummers et al 2008) have been reported between optical measurements of hemodynamic activity and electrophysiology in numerous experiments.…”

Section: Discussionmentioning

confidence: 99%

Encoding of graded changes in spatial specificity of prior cues in human visual cortex

Hara

Gardner

2014

Journal of Neurophysiology

View full text Add to dashboard Cite

Prior information about the relevance of spatial locations can vary in specificity; a single location, a subset of locations, or all locations may be of potential importance. Using a contrast-discrimination task with four possible targets, we asked whether performance benefits are graded with the spatial specificity of a prior cue and whether we could quantitatively account for behavioral performance with cortical activity changes measured by blood oxygenation level-dependent (BOLD) imaging. Thus we changed the prior probability that each location contained the target from 100 to 50 to 25% by cueing in advance 1, 2, or 4 of the possible locations. We found that behavioral performance (discrimination thresholds) improved in a graded fashion with spatial specificity. However, concurrently measured cortical responses from retinotopically defined visual areas were not strictly graded; response magnitude decreased when all 4 locations were cued (25% prior probability) relative to the 100 and 50% prior probability conditions, but no significant difference in response magnitude was found between the 100 and 50% prior probability conditions for either cued or uncued locations. Also, although cueing locations increased responses relative to noncueing, this cue sensitivity was not graded with prior probability. Furthermore, contrast sensitivity of cortical responses, which could improve contrast discrimination performance, was not graded. Instead, an efficient-selection model showed that even if sensory responses do not strictly scale with prior probability, selection of sensory responses by weighting larger responses more can result in graded behavioral performance benefits with increasing spatial specificity of prior information.

show abstract

Section: Discussionmentioning

confidence: 99%

Encoding of graded changes in spatial specificity of prior cues in human visual cortex

Hara

Gardner

2014

Journal of Neurophysiology

View full text Add to dashboard Cite

show abstract

“…R. Soc. B 371: 20150357 the relative linearity of these variables [17,19]. To do this, visual stimuli with different durations and spatial patterns were presented, while activity from LGN cells was monitored.…”

Section: Temporal and Spatial Summationmentioning

confidence: 99%

Neural–metabolic coupling in the central visual pathway

Freeman

2016

Phil. Trans. R. Soc. B

View full text Add to dashboard Cite

One contribution of 15 to a Theo Murphy meeting issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'. Studies are described which are intended to improve our understanding of the primary measurements made in non-invasive neural imaging. The blood oxygenation level-dependent signal used in functional magnetic resonance imaging (fMRI) reflects changes in deoxygenated haemoglobin. Tissue oxygen concentration, along with blood flow, changes during neural activation. Therefore, measurements of tissue oxygen together with the use of a neural sensor can provide direct estimates of neural-metabolic interactions. We have used this relationship in a series of studies in which a neural microelectrode is combined with an oxygen micro-sensor to make simultaneous co-localized measurements in the central visual pathway. Oxygen responses are typically biphasic with small initial dips followed by large secondary peaks during neural activation. By the use of established visual response characteristics, we have determined that the oxygen initial dip provides a better estimate of local neural function than the positive peak. This contrasts sharply with fMRI for which the initial dip is unreliable. To extend these studies, we have examined the relationship between the primary metabolic agents, glucose and lactate, and associated neural activity. For this work, we also use a Doppler technique to measure cerebral blood flow (CBF) together with neural activity. Results show consistent synchronously timed changes such that increases in neural activity are accompanied by decreases in glucose and simultaneous increases in lactate. Measurements of CBF show clear delays with respect to neural response. This is consistent with a slight delay in blood flow with respect to oxygen delivery during neural activation.This article is part of the themed issue 'Interpreting BOLD: a dialogue between cognitive and cellular neuroscience'.

show abstract

“…This USPIO agent exhibits a long blood half-life (5-6 h in rat (Li and Freeman, 2007)), enabling CBV measurements to be made over a prolonged period following intravenous administration. CBV fMRI data sets were acquired using the same imaging paradigm as for the BOLD acquisition.…”

Section: Animal Preparationmentioning

confidence: 99%

Real-time electrochemical monitoring of brain tissue oxygen: A surrogate for functional magnetic resonance imaging in rodents

et al. 2010

View full text Add to dashboard Cite

Long-term in-vivo electrochemistry (LIVE) enables real-time monitoring and measurement of brain metabolites. In this study we have simultaneously obtained blood oxygenation level dependent (BOLD) fMRI and amperometric tissue O 2 data from rat cerebral cortex, during both increases and decreases in inspired O 2 content. BOLD and tissue O 2 measurements demonstrated close correlation (r = 0.7898) during complete (0%) O 2 removal, with marked negative responses occurring ca. 30 s after the onset of O 2 removal. Conversely, when the inspired O 2 was increased (50, 70 and 100% O 2 for 1 min) similar positive rapid changes (ca. 15 s) in both the BOLD and tissue O 2 signals were observed. These findings demonstrate, for the first time, the practical feasibility of obtaining real-time metabolite information during fMRI acquisition, and that tissue O 2 concentration monitored using an O 2 sensor can serve as an index of changes in the magnitude of the BOLD response. As LIVE O 2 sensors can be used in awake animals performing specific behavioural tasks the technique provides a viable animal surrogate of human fMRI experimentation.

show abstract

High-Resolution Neurometabolic Coupling in the Lateral Geniculate Nucleus

Cited by 39 publications

References 45 publications

Encoding of graded changes in spatial specificity of prior cues in human visual cortex

Encoding of graded changes in spatial specificity of prior cues in human visual cortex

Neural–metabolic coupling in the central visual pathway

Real-time electrochemical monitoring of brain tissue oxygen: A surrogate for functional magnetic resonance imaging in rodents

Contact Info

Product

Resources

About