Effect of stimulus frequency on human cerebral hemodynamic responses to electric median nerve stimulation: a near-infrared spectroscopic study

We examined the effect of stimulus frequency on optically recorded hemodynamic responses to electric median nerve stimulation. Electric stimuli were delivered to the right median nerve with an intensity of 90% of motor threshold. Four different stimulus frequencies (2, 5, 10, and 20 Hz) were adminis...

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Bibliographic Details
Published in:Neuroscience letters 2003-11, Vol.352 (1), p.1-4
Main Authors: Tanosaki, Masato, Sato, Chie, Shimada, Miho, Iguchi, Yoshinobu, Hoshi, Yoko
Format: Article
Language:English
Subjects:
Adult
Analysis of Variance
Biological and medical sciences
Cerebral circulation. Blood-brain barrier. Choroid plexus. Cerebrospinal fluid. Circumventricular organ. Meninges
Electric median nerve stimulation
Electric Stimulation - methods
Fundamental and applied biological sciences. Psychology
Hemodynamic response
Hemodynamics - physiology
Humans
Male
Median Nerve - physiology
Near-infrared spectroscopy
Primary somatosensory cortex
Secondary somatosensory cortex
Somatosensory Cortex - blood supply
Somatosensory Cortex - physiology
Spectroscopy, Near-Infrared - methods
Stimulus frequency
Vertebrates: nervous system and sense organs
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Summary:We examined the effect of stimulus frequency on optically recorded hemodynamic responses to electric median nerve stimulation. Electric stimuli were delivered to the right median nerve with an intensity of 90% of motor threshold. Four different stimulus frequencies (2, 5, 10, and 20 Hz) were administered in each subject. By means of a multi-channel near-infrared spectroscopic instrument, changes in concentration of oxygenated hemoglobin were continuously measured over the left scalp. After 20 Hz stimulation, we found two spatially and temporally distinct hemodynamic responses. One lasted beyond 60 s, and the center of this response was located over the secondary somatosensory area. The other had a transient duration starting immediately after the stimulus onset and was located in the primary somatosensory hand area. Both responses were linearly augmented as a function of the stimulus frequency. Since temporal activation patterns are different in two somatosensory areas, real-time optical monitoring is necessary in evaluation of hemodynamic responses to electric nerve stimulation.
ISSN:0304-3940
1872-7972
DOI:10.1016/j.neulet.2003.08.055