Relationship Between Subjective Ratings of Answers and Behavioral and Autonomic Nervous Activities During Creative Problem-Solving via Online Conversation.

Creative problem solving has been important for the advent of new technologies. In this study, we hypothesized that subjective ratings of answers should be useful for evaluating the answer quality in creative problem solving. To test this hypothesis and extract objective indicators of the subjective ratings of answers, we evaluated the relationship between subjective ratings of task performance and behavioral and autonomic nervous activities during a creative problem-solving task performed via online conversation. The task involved an answerer and a supporter, and in the experiment, each pair performed 10 trials. The trials were categorized as highly or lowly rated according to the answerer's confidence in the answer. The task performance and behavioral and autonomic nervous activities were then compared between these categories of trials. Behavioral activity was evaluated via movements and speech activities, while for autonomic nervous activity, sympathetic nervous activity (SNA) was evaluated via skin conductance. The task performance was significantly better in the highly rated trials, whereas there were no significant differences in the behavioral activities between the highly and lowly rated trials. Moreover, in the highly rated trials, the skin conductance of the answerer was significantly high, whereas that of the supporter was significantly low. The results support the hypothesis and suggest that contrasting differences in SNA between an answerer and a supporter are indicators of the subjective ratings of answers in creative problem solving.

Achieving affective human-virtual agent communication by enabling virtual agents to imitate positive expressions.

Affective communication, communicating with emotion, during face-to-face communication is critical for social interaction. Advances in artificial intelligence have made it essential to develop affective human-virtual agent communication. A person's belief during human-virtual agent interaction that the agent is a computer program affects social-cognitive processes. Whether this belief interferes with affective communication is an open question. We hypothesized that the imitation of a positive emotional expression by a virtual agent induces a positive emotion, regardless of the belief. To test this hypothesis, we conducted an fMRI study with 39 healthy volunteers, who were made to believe that a virtual agent was either a person or a computer. They were instructed to smile, and immediately afterwards, the virtual agent displayed a positive, negative, or neutral expression. The participants reported a positive emotion only when their smile was imitated by the agent's positive expression regardless of their belief. This imitation activated the participants' medial prefrontal cortex and precuneus, which are involved in anthropomorphism and contingency, respectively. These results suggest that a positive congruent response by a virtual agent can overcome the effect of believing that the agent is a computer program and thus contribute to achieving affective human-virtual agent communication.

Multiple-Time-Scale Analysis of Attention as Revealed by EEG, NIRS, and Pupil Diameter Signals During a Free Recall Task: A Multimodal Measurement Approach.

Attention plays a fundamental role in acquiring and understanding information. Therefore, it is useful to evaluate attention objectively in such fields as education and mental health. Aimed at extracting objective indicators of attention from physiological signals, this study examined the characteristics of electroencephalography (EEG), near-infrared spectroscopy (NIRS), and pupil diameter signals during a free recall task. The objective was to clarify the temporal characteristics of these signals in relation to attention. We used a free recall task as a cognitive task with an attentional load. The participants attempted to memorize and then recall 13 serially presented words. Our hypothesis was that the significant physiological responses should differ depending on the time scale of the attention evaluation. The physiological responses were compared on the basis of differences between success and failure to recall a word on a short time scale, in terms of the attentional state among five serial position groups on a middle time scale, and on the basis of differences between trials with many and few words recalled on a long time scale. We found that the response of each physiological signal depended on the attention in the different time-scale comparisons. (1) The P300 amplitudes of the EEG signals for the words that were recalled were significantly higher than those for the words that were not recalled. (2) Pupillary dilation differed significantly depending on the serial position group. (3) Functional connectivity in the right hemisphere revealed by NIRS was significantly stronger in trials with many words recalled than in those with few words recalled. Different temporal characteristics of physiological signals with respect to attention were suggested by multimodal measurement and multiple-time-scale analysis. Consideration of these characteristics should help in the development of applications requiring objective attention evaluation.

Denoising of neuronal signal from mixed systemic low-frequency oscillation using peripheral measurement as noise regressor in near-infrared imaging.

Functional near-infrared spectroscopy (fNIRS) is a noninvasive functional imaging technique measuring hemodynamic changes including oxygenated ( O 2 Hb ) and deoxygenated (HHb) hemoglobin. Low frequency (LF; 0.01 to 0.15 Hz) band is commonly analyzed in fNIRS to represent neuronal activation. However, systemic physiological artifacts (i.e., nonneuronal) likely occur also in overlapping frequency bands. We measured peripheral photoplethysmogram (PPG) signal concurrently with fNIRS (at prefrontal region) to extract the low-frequency oscillations (LFOs) as systemic noise regressors. We investigated three main points in this study: (1) the relationship between prefrontal fNIRS and peripheral PPG signals; (2) the denoising potential using these peripheral LFOs, and (3) the innovative ways to avoid the false-positive result in fNIRS studies. We employed spatial working memory (WM) and control tasks (e.g., resting state) to illustrate these points. Our results showed: (1) correlation between signals from prefrontal fNIRS and peripheral PPG is region-dependent. The high correlation with peripheral ear signal (i.e., O 2 Hb ) occurred mainly in frontopolar regions in both spatial WM and control tasks. This may indicate the finding of task-dependent effect even in peripheral signals. We also found that the PPG recording at the ear has a high correlation with prefrontal fNIRS signal than the finger signals. (2) The systemic noise was reduced by 25% to 34% on average across regions, with a maximum of 39% to 58% in the highly correlated frontopolar region, by using these peripheral LFOs as noise regressors. (3) By performing the control tasks, we confirmed that the statistically significant activation was observed in the spatial WM task, not in the controls. This suggested that systemic (and any other) noises unlikely violated the major statistical inference. (4) Lastly, by denoising using the task-related signals, the significant activation of region-of-interest was still observed suggesting the manifest task-evoked response in the spatial WM task.

Rearrangeable and exchangeable optical module with system-on-chip for wearable functional near-infrared spectroscopy system.

We developed a system-on-chip (SoC)-incorporated light-emitting diode (LED) and avalanche photodiode (APD) modules to improve the usability and flexibility of a fiberless wearable functional near-infrared spectroscopy (fNIRS) system. The SoC has a microprocessing unit and programmable circuits. The time division method and the lock-in method were used for separately detecting signals from different positions and signals of different wavelengths, respectively. Each module autonomously works for this time-divided-lock-in measurement with a high sensitivity for haired regions. By supplying [Formula: see text] of power and base and data clocks, the LED module emits both 730- and 855-nm wavelengths of light, amplitudes of which are modulated in each lock-in frequency generated from the base clock, and the APD module provides the lock-in detected signals synchronizing with the data clock. The SoC provided many functions, including automatic-power-control of the LED, automatic judgment of detected power level, and automatic-gain-control of the programmable gain amplifier. The number and the arrangement of modules can be adaptively changed by connecting this exchangeable modules in a daisy chain and setting the parameters dependent on the probing position. Therefore, users can configure a variety of arrangements (single- or multidistance combinations) of them with this module-based system.

A device for co-culturing autonomic neurons and cardiomyocytes using micro-fabrication techniques.

It is still unclear how the activity of sympathetic and parasympathetic neurons influences the activity of cardiomyocytes in culture. We developed a device for co-culturing sympathetic neurons, parasympathetic neurons, and cardiomyocytes using micro-fabrication techniques. Morphological connections between each type of autonomic neuron and the cardiomyocytes were observed by immunostaining. The inter-beat-interval (IBI) of the cardiomyocytes was modulated after electrically stimulating each type of autonomic neuron. Modulation of the IBI was blocked by the addition of pharmacological blockers to the culture medium. These results suggest that the co-culture device can be utilized to understand how the activity of sympathetic neurons and parasympathetic neurons influences the activity of cardiomyocytes in the culture environment.

Circadian changes of influence of swallowing on heart rate variability with respiratory-phase domain analysis.

Respiratory sinus arrhythmia (RSA) is known as an index of cardiac vagal activity and useful to evaluate the response of the cardiovascular system to external stimuli. As an external stimulation, swallowing is known to strongly affect the cardiovascular system. However, the influence of swallowing and its relation with the autonomic nervous system remain incompletely understood. In this study, since autonomic nervous control of the cardiovascular system has a circadian rhythm, we evaluated circadian changes of influence of swallowing on RSA. Measurements were conducted on healthy humans with periodic swallowing in the morning, afternoon, and evening. RSA waveforms were extracted from an instantaneous R-R Interval (RRI) as functions of the respiratory phase and the data were divided into three subsets with respiration with swallowing, one respiration after the swallowing, and normal respiration. As a result, the RSA amplitude during respiration with swallowing was larger in the morning than in the evening. In addition, the minimum RRI during respiration with swallowing was larger in the morning than in the afternoon and evening. Thus, circadian changes of influence of swallowing on the RSA amplitude are extracted and swallowing-induced tachycardia is different with different states of autonomic nervous activity. Therefore, vagal activity should largely contribute to tachycardia induced by swallowing and evaluation of circadian changes of influences of external stimuli would be useful to investigate the mechanisms of response of the cardiovascular system to external stimuli.

[Thymic carcinoma. A clinicopathological study of seven patients].

The treatment of seven cases of thymic carcinoma is reported. According to the Masaoka classification of the disease, there were five cases of stage III and two of stage IVb. Five were identified histopathologically as squamous cell carcinoma, one as undifferentiated carcinoma, and one as small cell neuroendocrine carcinoma. Surgery was performed during the course of chemotherapy and radiotherapy in 5 cases, and in 2, the organs infiltrated by neoplastic cells were partially excised together. Radiotherapy was performed as adjuvant therapy in one case of partial excision. In another case, after six years of chemotherapy and radiotherapy that yielded a partial response (PR), cancerous infiltration of the chest wall occurred, and partial removal of the chest wall became necessary. After the remaining case showed a PR to chemotherapy, complete macroscopic excision of the tumor was undertaken, but mediastinal lymph gland metastasis was present, and so radiotherapy was also initiated. In two cases, surgery was not performed. One of these was treated with chemotherapy alone, the other, only with radiotherapy. The mean survival period of the five patients who died as a result of their tumors was 44.8 months. One of the two who survived for over four years had squamous cell carcinoma, the other, undifferentiated carcinoma. The case of small cell neuroendocrine carcinoma was assessed as having a PR, and so complete extraction of the thymic neoplasm was carried out, and followed with radiotherapy. This patient is still alive.