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Updated: Jul 25, 2026
Topographical Estimation of Visual Population Receptive Fields by fMRI
Published on: February 3, 2015
Visual cortex reactivity in sedated children examined with perfusion MRI (FAIR)
A P Born1, E Rostrup, M J Miranda
1Danish Research Centre for Magnetic Resonance, Hvidovre Hospital, Glostrup, Denmark. pborn@magnet.drcmr.dk
Insights
Sedated children exhibit an unusual brain response to visual stimuli, showing decreased regional cerebral blood flow (rCBF) instead of the expected increase. This finding may explain the negative blood oxygenation level dependent (BOLD) signal observed in pediatric neuroimaging studies.
Area of Science:
- Neuroimaging
- Pediatric Neurology
- Physiology
Background:
- Sedated children display an inverse blood oxygenation level dependent (BOLD) functional MRI signal response to visual stimulation.
- The underlying causes of this inverse response, particularly the interplay between metabolism and cerebral blood flow, remain unclear.
Purpose of the Study:
- To investigate regional cerebral blood flow (rCBF) changes during visual stimulation in sedated children and alert adults.
- To explore the relationship between rCBF and BOLD signals in pediatric versus adult neuroimaging.
Main Methods:
- Utilized arterial water spin labeling (FAIR) and BOLD fMRI techniques.
- Compared brain activity in four sedated children (4-71 months) with four alert adults using a 1.5T MR scanner.
Main Results:
- In sedated children, FAIR signal decreased (mean -0.96%), and BOLD signal decreased (mean -2.03%).
- In alert adults, FAIR signal increased (mean 0.88%), and BOLD signal increased (mean 2.63%).
- Perfusion MRI did not detect an rCBF increase in children, but indicated a FAIR signal decrease.
Conclusions:
- The observed rCBF decrease in the primary visual cortex of sedated children during stimulation is a novel finding.
- This rCBF decrease may explain the negative BOLD response in pediatric neuroimaging.
- Further research is needed to determine if this response is age-dependent or related to sedation/sleep states.
Abstract:
Sleeping and sedated children can respond to visual stimulation with a decrease in blood oxygenation level dependent (BOLD) functional MRI signal response. The contribution of metabolic and hemodynamic parameters to this inverse signal response is incompletely understood. It has been hypothesized that it is caused by a relatively greater increase of oxygen consumption compared to rCBF (regional cerebral blood flow) increase. We studied the rCBF changes during visual stimulation in four sedated children, aged 4-71 months, and four alert adults, with an arterial water spin labeling technique (FAIR) and BOLD fMRI in a 1.5T MR scanner. In the children, FAIR signal decreased by a mean of 0.96% (range 0.77-1.05) of the baseline periods of the non-selective images, while BOLD signal decreased by 2.03% (range 1.99-2.93). In the adults, FAIR and BOLD signal increased by 0.88% (range 0.8-0.99) and 2.63% (range 1.99-2.93), respectively. Thus, in the children, an rCBF increase could not be detected by perfusion MRI, but indications of a FAIR signal decrease were found. An rCBF decrease in the primary visual cortex during stimulation has not been reported previously, but it is a possible explanation for the negative BOLD response. Future studies will have to address if this response pattern is a consequence of age or sleep/sedation.
