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For near infrared red spectroscopy (NIRS), the debate over the reliability of its absolute value is ongoing, and discussed in this paper with alpha-blocking task. The purpose of the study is step by step clarification on NIRS reliability. The method in this paper is the evaluation with a task that is clinically important and has achieved a wide consensus and a diagnostics of its measurement. From this viewpoint, this paper discussed the NIRS measurement, with the electroencephalography (EEG) measurement of alpha-blocking as the task. Based on the EEG measurement results of alpha-blocking, we investigated the characteristic changes in the NIRS measurements; a correlation between the two measurements was found (0.806), based on alpha-rhythm patterns of EEG and the increasing or decreasing patterns of oxygen metabolism on NIRS. In addition, a correlation was found between complexities in the two measurements (0.677). The variation level of the complexity in the EEG measurements was 7.14 times larger compared with that of NIRS on average which suggests that the EEG measurements included much information than the NIRS measurements for alpha-blocking task. Despite, the correlation results suggest a possibility of NIRS application to alpha-blocking diagnosis. These numericals contribute to step by step clarification on NIRS reliability.

The risk to fall has clinical relevance in prognosis of elderly people. We analyzed aging effects on the physiological properties of the vertical ground reaction force of healthy subjects and examined whether it can be used as an index for postural instability and risk to fall.We analyzed stabilometric data from 1795 healthy volunteers (3 - 93 years old). Vertical acceleration was computed from the load-cell records and underwent frequency analysis. The multiple comparison test was performed by age groups at every frequency within the detected significant band.Variances in vertical acceleration were high in juveniles and elderly people. Both acceleration power at 1.5-2 Hz and power ratio of eye closure to the open eye at 2-6 Hz were markedly high and decreased by 20 years of age. Age groups from 20 to 60 years had low stable power profiles and the age groups over 60 years showed increased power at 5-8 Hz relative to aging.Our findings suggest that the postural instability of young people evoked by eye-closure accounts for 3-Hz vibration and that increased power in elderly subjects around 6.5 Hz has a strong correlation with aging.

Information volume, evoked potentials and reaction time with voice were studied for reading Japanese cursive syllabary “HIRAGANAs”. Thirty-two EEGs with a filter from DC to 100 Hz were sampled at 2 kHz into 24 bits during 1000 ms after displaying HIRAGANAs. Evoked potentials were marked over the frontal and occipital areas, because of referring to scalp central areas, then the potentials were converted with the current source derivation. Reaction times for voice were 623±137 for one HIRAGANA, 819±136 for two HIRAGANAs, 993±169 ms for four HIRAGANAs. Broad central areas showed graded different potentials between reading silently and aloud, corresponding to the volume of the information, after 100 ms before 500 ms displaying HIRAGANAs.

To study cerebral cortical function in equilibrium, cortical oxyhemoglobin saturation rate was measured during Caloric test for five volunteers. Near-infrared spectroscopy (NIRS) measuring backscattered reflection is a non-invasive, good method to study human cortical activation. Over both temporal areas, the oxyhemoglobin saturation rate changed during the irrigation to the auricle, the irrigation to the ear meatus, and during nystagmus. Caloric test induced various cortical activation; e.g., the sensation in irrigating iced water, vestibulo-autonomic response, vestibulo-ocular response, anticipation to the stimuli and so on.

Dipole source localization corresponding to interictal spikes were estimated using EEG dipole tracing with a realistic three-shell head model in three patients with cryptogenic gelastic epilepsy. The dipole sources in two patients, whose gelastic seizures were accompanied by a subjective feeling of mirth, were estimated in the right or left medio-basal temporal regions. In the other patient, with gelastic seizures without a sense of mirth, the dipole sources were localized in the right frontal region corresponding to the anterior cingulate. The results suggest that the neural activities in hippocampal regions are involved with the generation of gelastic seizures with a sense of mirth and those in the cingulate might be associated with the motor act of laughter.

We studied precise spectra of evoked EEGs in the word recognition analyzed with multiple band-pass filters (MBFA). The filter was infinite impulse response in 2nd order. Firstly, a signal swept from 5 to 100 Hz sine wave was tested with MBFA, fast Fourier transform and Wavelet transform. Ten evoked EEGs with word visual stimuli were recorded from three volunteers. The EEGs were sampled at 1 kHz in 14 bits for 1 s, and were analyzed with MBFA to make spectra from 5 to 100 Hz, and the spectra were averaged 10 times for observation. Evoked powers were noted at alpha band over the occipital area and suppressed powers were noted at beta and alpha bands afterward. Gamma bands were noted to be evoked over the posterior central area in the normalized Event-related spectra.