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Imaging optical reflectance in rodent barrel and forelimb sensory cortex
S M Narayan1, E M Santori, A J Blood
1Department of Neurology, UCLA School of Medicine 90024, USA.
Neuroimage
|June 1, 1994
Summary
Researchers developed a new system for repeatable imaging of rapid brain function in rodent primary somatosensory cortex (S-I). This technique uses intrinsic signals to visualize dynamic brain activity over seconds.
Area of Science:
- Neuroscience
- Optical Imaging
- Physiology
Background:
- Dynamic brain function studies benefit from novel neuroimaging.
- Previous methods had limitations in capturing rapid neural activity.
Purpose of the Study:
- To develop a system for repeatable imaging of rapid function in rodent primary somatosensory cortex (S-I).
- To characterize stimulus-related optical reflectance changes in the S-I cortex.
Main Methods:
- Used a cooled charge-coupled device (CCD) camera to acquire images at 550, 610, and 850 nm.
- Stimulated rodent S-I cortex via vibrissal deflection or forepaw stimulation.
- Averaged stimulus-related reflectance changes across multiple trials to create functional maps.
Main Results:
- Identified two distinct spatiotemporal components of optical activity (intrinsic signals) in the S-I cortex.
- Observed a diffuse signal starting 0.5-1s post-stimulus with a 4-5s duration, and a delayed macrovenous signal.
- Confirmed the functional nature of optical signals using evoked potentials.
Conclusions:
- Successfully imaged functional reflectance changes in rodent S-I cortex on a second timescale.
- The observed optical activity is consistent with microvascular recruitment and chromophore redox changes.
- The developed CCD system enables repeatable imaging of rapid dynamic brain function.