Comparison of Somatosensory Evoked Potentials and Cerebral Blood Oxygenation Changes in the Sensorimotor Cortex During Activation in the Rat
The relationship between changes in cerebral blood oxygenation and neuronal activity remains to be fully established. We compared somatosensory evoked potentials (SEP) and evoked cerebral blood oxygenation (CBO) changes in the sensorimotor cortex of the rat. In rats anesthetized with urethane and alpha-chloralose, we measured SEP and CBO using visible light spectroscopy (VLS) during neuronal activity. Increase of stimulus frequency caused a decrease of SEP amplitude, but an increase in concentration changes of deoxy-Hb and oxygen satu-ration. The difference in frequency responses between SEP and CBO might be caused by activation of inhibitory neurons, which could suppress excitatory neu-rons at high stimulus frequencies; activation of inhibitory neurons could reduce SEP amplitude, and increase oxygen saturation due to an increase of evoked cere-bral blood flow.
KeywordsOxygen Saturation Sensorimotor Cortex Stimulus Frequency Inhibitory Neuron Somatosensory Evoke Potential
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