Working-memory evaluation based on EEG signals during n-back tasks.

Working memory is the cognitive process of receiving, processing, and communicating information. Early evaluation and training may help to prevent a marked decline in working-memory ability. The aim of this study was to establish an n-back task system for objectively evaluating the working-memory ability based on the θ power, the γ power, and the degree of θ-γ synchronization. Our experiments were divided into four memory loads (1-back to 4-back) and further divided into digital and matrix stimulation modes. The γ band was divided into three components (γ1: 30-50 Hz, γ2: 50-70 Hz, and γ3: 70-90 Hz). The study recruited 23 healthy young subjects. The obtained results indicate that accuracy rates might be inappropriate for assessing the working memory. The θ power relates to working-memory recognition while the γ power varied with the memory load. Besides, a higher load level should be more appropriate for assessing the working-memory ability. Finally, the number of θ-γ3 couplings was highest between the frontal area and Pz and O2. In summary, the results of this study may be useful in multiple evaluations of working memory, and may lead to a wider variety of clinical applications in the future.

Dynamics of the reactions of O(1D) with CD3OH and CH3OD studied with time-resolved Fourier-transform IR spectroscopy.

We investigated the reactivity of O((1)D) towards two types of hydrogen atoms in CH(3)OH. The reaction was initiated on irradiation of a flowing mixture of O(3) and CD(3)OH or CH(3)OD at 248 nm. Relative vibration-rotational populations of OH and OD (1 ≤ v ≤ 4) states were determined from their infrared emission recorded with a step-scan time-resolved Fourier-transform spectrometer. In O((1)D) + CD(3)OH, the rotational distribution of OD is nearly Boltzmann, whereas that of OH is bimodal; the product ratio [OH]/[OD] is 1.56 ± 0.36. In O((1)D) + CH(3)OD, the rotational distribution of OH is nearly Boltzmann, whereas that of OD is bimodal; the product ratio [OH]/[OD] is 0.59 ± 0.14. Quantum-chemical calculations of the potential energy and microcanonical rate coefficients of various channels indicate that the abstraction channels are unimportant and O((1)D) inserts into the C-H and O-H bonds of CH(3)OH to form HOCH(2)OH and CH(3)OOH, respectively. The observed three channels of OH are consistent with those produced via decomposition of the newly formed OH or the original OH moiety in HOCH(2)OH or decomposition of CH(3)OOH. The former decomposition channel of HOCH(2)OH produces vibrationally more excited OH because of incomplete intramolecular vibrational relaxation, and decomposition of CH(3)COOH produces OH with greater rotational excitation, likely due to a large torque angle during dissociation. The predicted [OH]/[OD] ratios are 1.31 and 0.61 for O((1)D) + CD(3)OH and CH(3)OD, respectively, at collision energy of 26 kJ mol(-1), in satisfactory agreement with the experimental results. These predicted product ratios vary weakly with collision energy.