Abstract
Purpose: :
Near-infrared spectroscopy(NIRS) is a method to measure dynamic changes in hemoglobin concentration evoked by brain activity. We recorded NIRS and VEP simultaneously with pattern stimulus. The purpose of the present study is to investigate the relations between NIRS and VEP to pattern stimulus.
Methods: :
We recorded NIRS and VEPs simultaneously with both pattern reversal hemi-field and full-field stimulus in healthy volunteers. For recording of NIRS,we used a near-infrared spectroscopy system(FOIRE-3000,Shimadzu Corporation,Kyoto,Japan) with wave-length of 780,805 and 830 nm to monitor changes in the oxyhemoglobin, deoxyhemoglobin and total hemoglobin respectively with 48 channels over the occipital lobe. VEPs were recorded with positve electrodes placed at O1 and O2. Black and white checker-boards on a CRT monitor were used as stimuli. A check size was 1.7 degree and reversal rate was 6 reversal/second. We recorded with 3 stimulus fields, right and left hemifield and full field. Every 20 seconds the checker-boards were altered right-,left-hemifield and full field,with resting period of 20 seconds.
Results: :
In VEPs, clear responses were observed in contralateral occipital lobe with hemifield stimulus and both occipital lobe with full field stimulus in all cases. But in NIRS, neither significant increase in oxyhemoglobin nor decrease in deoxyhemoglobin were observed in several cases.
Conclusions: :
Both VEPs and NIRS can reflect the activity of occipital lobe to pattern reversal stimulus, but the sensitivity might be higher for VEPs in the present conditions.
Keywords: neuro-ophthalmology: cortical function/rehabilitation • visual cortex