Emi Nishina

Neural networks for generation and suppression of alpha rhythm: a PET study.

TO study neuronal activities that influence the generation of the alpha rhythm, we used positron emission tomography and simultaneous recording of the electroencephalogram (EEG) in normal volunteers and under passive conditions. A negative correlation between regional cerebral blood flow and alpha power was found in the occipital cortex, consistent with the visual modality-specific reactivity of the alpha rhythm. A positive correlation was found in the pons, midbrain, hypothalamus, amygdala, the basal prefrontal cortex, insula and the right dorsal premotor cortex. Neuronal activities of the brain stem and limbic system that are positively correlated with alpha power may provide an anatomical basis for studies of the relationship between emotional state and brain rhythm in health and disease.

Modulatory effect of inaudible high-frequency sounds on human acoustic perception

We evaluated the effects of the intensity of an inaudible high-frequency component (HFC) of sound on human responses by employing a multi-parametric approach consisting of behavioral measurements of the comfortable listening level (CLL), psychological measurements of the subjective impression of sounds, and physiological measurements using electroencephalogram (EEG). Increasing the intensity of the inaudible HFC resulted in a significant increase in the CLL, the subjective impression of sounds, and the occipital alpha frequency component of the spontaneous EEG. These effects peaked with an increase of 6 dB in HFC intensity. The results of the present study suggest that the intensity of inaudible HFC non-linearly modulates human sound perception.

Analysis of music–brain interaction with simultaneous measurement of regional cerebral blood flow and electroencephalogram beta rhythm in human subjects

To elucidate the neural substrates of the receptive aspect of music, we measured regional cerebral blood flow (rCBF) with positron emission tomography (PET) and simultaneously recorded the electroencephalogram (EEG) in eight normal volunteers. Compared with the rest condition, listening to music caused a significant increase in EEG beta power spectrum (13-30 Hz) averaged over the posterior two third of the scalp. The averaged beta power spectrum was positively correlated with rCBF in the premotor cortex and adjacent prefrontal cortices bilaterally, the anterior portion of the precuneus and the anterior cingulate cortex in both the rest and the music conditions. Listening to music newly recruited the posterior portion of the precuneus bilaterally. This may reflect the interaction of the music with the cognitive processes, such as music-evoked memory recall or visual imagery.

Electroencephalographic measurement of possession trance in the field

OBJECTIVES To verify the utility of a portable electroencephalogram (EEG) measurement system developed for investigating spontaneous EEG from vigorously moving healthy subjects in a possession trance under a natural condition. METHODS A portable multi-channel EEG telemetry system was developed to record the EEGs of 3 healthy male Balinese while they were performing a ritual dedicatory drama in the field. After reducing extraneous artifacts using a digital filter, the EEGs and their power spectra were analyzed in terms of evolution from one state to another. RESULTS During the drama, one of the subjects became possessed while the others did not. The EEG of the possessed subject did not show any pathological findings including epileptic discharges, but indicated enhanced power in the theta and alpha frequency bands during the trance. This finding was not observed in the other two subjects, who did not go into trances, with no pathological EEG findings. CONCLUSIONS The measurement system and data analysis methods we developed have allowed us, for the first time, to obtain an EEG from healthy subjects who are vigorously moving while in a possession trance. The present technique enables us to use a spontaneous EEG as a marker of the underlying physiology of a state of possession trance.

An effective hierarchical model for the biomolecular covalent bond: An approach integrating artificial chemistry and an actual terrestrial life system

Under the AChem paradigm and the programmed self-decomposition (PSD) model, we propose a hierarchical model for the biomolecular covalent bond (HBCB model). This model assumes that terrestrial organisms arrange their biomolecules in a hierarchical structure according to the energy strength of their covalent bonds. It also assumes that they have evolutionarily selected the PSD mechanism of turning biological polymers (BPs) into biological monomers (BMs) as an efficient biomolecular recycling strategy. We have examined the validity and effectiveness of the HBCB model by coordinating two complementary approaches: biological experiments using existent terrestrial life, and simulation experiments using an AChem system. Biological experiments have shown that terrestrial life possesses a PSD mechanism as an endergonic, genetically regulated process and that hydrolysis, which decomposes a BP into BMs, is one of the main processes of such a mechanism. In simulation experiments, we compared different virtual self-decomposition processes. The virtual species in which the self-decomposition process mainly involved covalent bond cleavage from a BP to BMs showed evolutionary superiority over other species in which the self-decomposition process involved cleavage from BP to classes lower than BM. These converging findings strongly support the existence of PSD and the validity and effectiveness of the HBCB model.

Frequencies of inaudible high-frequency sounds differentially affect brain activity: positive and negative hypersonic effects.

The hypersonic effect is a phenomenon in which sounds containing significant quantities of non-stationary high-frequency components (HFCs) above the human audible range (max. 20 kHz) activate the midbrain and diencephalon and evoke various physiological, psychological and behavioral responses. Yet important issues remain unverified, especially the relationship existing between the frequency of HFCs and the emergence of the hypersonic effect. In this study, to investigate the relationship between the hypersonic effect and HFC frequencies, we divided an HFC (above 16 kHz) of recorded gamelan music into 12 band components and applied them to subjects along with an audible component (below 16 kHz) to observe changes in the alpha2 frequency component (10–13 Hz) of spontaneous EEGs measured from centro-parieto-occipital regions (Alpha-2 EEG), which we previously reported as an index of the hypersonic effect. Our results showed reciprocal directional changes in Alpha-2 EEGs depending on the frequency of the HFCs presented with audible low-frequency component (LFC). When an HFC above approximately 32 kHz was applied, Alpha-2 EEG increased significantly compared to when only audible sound was applied (positive hypersonic effect), while, when an HFC below approximately 32 kHz was applied, the Alpha-2 EEG decreased (negative hypersonic effect). These findings suggest that the emergence of the hypersonic effect depends on the frequencies of inaudible HFC.

Multidisciplinary study on the hypersonic effect

Abstract Although it is generally accepted that humans cannot perceive sounds in the frequency range above 20 kHz, the question of whether the coexistence of such “inaudible” high-frequency components (HFC) with audible low-frequency components (LFC) may have any biological effects on listeners remains unanswered. We have attempted to address this complex problem using a multidisciplinary approach: combined evaluation of physiological, psychological and behavioral responses. Physiological measurement revealed that the combined presentation of the HFC and LFC, compared with the presentation of the only LFC, significantly increased the power of the occipital alpha-EEG in parallel with the rCBF in the brainstem and left thalamus. The power of the occipital alpha-EEG correlated significantly with the rCBF in the left thalamus. Psychological evaluation indicated that the subjects felt the sound containing HFC to be more pleasant than the only LFC. Behavioral evaluation showed that the subjects spontaneously adjusted the volume of the sound level at a greater magnitude when listening to the sound containing HFC compared with the only LFC. The line of evidence suggests the existence of a previously unrecognized response to complex sound containing particular types of high frequencies above the audible range. We term this phenomenon the “hypersonic effect.”

Artificial life based on the programmed self-decomposition model, SIVA

To examine the effect and significance of the phenomenon of death, we have developed an artificial life simulator, SIVA-III (simulator for individuals of virtual automata III), based on a “programmed self-decomposition model”. The architecture of this simulator consists of a “finite heterogeneous habitation environment” and “artificial life with programmed individual death and concurrent self-decomposition”. We conducted experiments under various settings to comparare and contrast mortal life and immortal life. The results clearly demonstrated the validity of a self-decomposing, programmed individual death, and the limitations inherent in immortal life, suggesting a striking superiority of mortal life over immortal life.

Evolutionary acquisition of a mortal genetic program: The origin of an altruistic gene

As part of our research on programmed self-decomposition, we formed the hypothesis that originally immortal terrestrial organisms evolve into ones that are programmed for autonomous death. We then conducted evolutionary simulation experiments in which we examined this hypothesis using an artificial ecosystem that we designed to resemble a terrestrial ecosystem endowed with artificial chemistry. Notable results corroborating our hypothesis were obtained, which showed that mortal organisms emerged from indigenous immortal organisms through mutation; such mortal organisms survived and left behind offspring, albeit very rarely, and, having survived, surpassed immortal organisms without exception. In this article, we report the details of the above findings and also discuss a background framework we previously constructed for approaching altruism.

Evaluation of a 3-D visual programming environment in an introductory course of object-oriented programming

A newly developed visual programming environment has been evaluated. It allows students to visualize and manipulate programs in 3D representation. That visual programming environment is expected to enhance motivation to programming, understanding of programs, and efficiency of programming education. An experiment was conducted to evaluate the newly developed programming environment. The experiment included lectures, exercises of programming, achievement tests, video recordings, monitoring of keyboard and mouse activities and questionnaires.