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Masako Sugai, Masaharu Adachi; The Model-based Nirs Data Analysis On Visual Stimulus Of Different Temporal And Spatial Frequency In Normal Subjects. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6103.
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NIRS (Near infra-red spectroscopy) is a spectroscopic method to assess dynamic changes in the hemoglobin concentration evoked by brain activity. We examined the effects of the different spatial frequency and temporal frequency of stimuli on the NIRS data in occipital area of normal subjects.
Four normal subjects took part in the experiment. The visual stimuli were black and white checkerboard pattern reversing at 10 Hz and 2Hz(duty cycle:50%).The checkerboard size was 10’ and 50’ . Block design was adopted, which consists of pretask(20sec),task(20sec)and posttask(20sec). Each session contains five repetition of series. In task the stimuli were presented 50cm ahead of the subjects, of which the visual field was 13*10degree. All the experiment were done in the quiet and dim room . For analyzing the NIRS time series, General linear model (GLM) is applied. We used a Gaussian function as the hemodynamic response function (HRF). MATLAB 2010a (MathWorks) was used for statistical analyses.Each experiment was performed according to the tenets of the Declaration of Helsinki and under the approval of the Ethics Committee of the Tokyo Denki University. Informed consent was obtained from all the subjects after explanation of the nature and possible consequences of the study.
Concentration changes in oxygenated hemoglobin were analyzed. In three of four subjects, the 50’ check size was realized the strong activation on 10 Hz in striate, while 2 Hz in extrastriate. As for 10’ check size and 2 Hz, activation was observed in extrastriate of all subjects. On the other hand, as for 10’ check size and 10 Hz, activation was seen in three subjects.
To analyze the discrimination of NIRS responses, we used visual stimulus of different spatial and temporal frequencies. The difference between cortical responses could contribute to the modeling of information processing in the visual systems.
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