Masako Morimoto

Spontaneous Slow Fluctuation of EEG Alpha Rhythm Reflects Activity in Deep-Brain Structures: A Simultaneous EEG-fMRI Study

The emergence of the occipital alpha rhythm on brain electroencephalogram (EEG) is associated with brain activity in the cerebral neocortex and deep brain structures. To further understand the mechanisms of alpha rhythm power fluctuation, we performed simultaneous EEGs and functional magnetic resonance imaging recordings in human subjects during a resting state and explored the dynamic relationship between alpha power fluctuation and blood oxygenation level-dependent (BOLD) signals of the brain. Based on the frequency characteristics of the alpha power time series (APTS) during 20-minute EEG recordings, we divided the APTS into two components: fast fluctuation (0.04–0.167 Hz) and slow fluctuation (0–0.04 Hz). Analysis of the correlation between the MRI signal and each component revealed that the slow fluctuation component of alpha power was positively correlated with BOLD signal changes in the brain stem and the medial part of the thalamus and anterior cingulate cortex, while the fast fluctuation component was correlated with the lateral part of the thalamus and the anterior cingulate cortex, but not the brain stem. In summary, these data suggest that different subcortical structures contribute to slow and fast modulations of alpha spectra on brain EEG.

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.

Relationship between spontaneous change of arousal level and brain activity

P2-n14 Acute induction of Eya3 by late-night light stimulation triggers TSH expression in photoperiodism Koh-hei Masumoto 1 , Maki Ukai-Tadenuma 2, Takeya Kasukawa 3, Mamoru Nagano 1, Kenichiro D. Uno 3, Kaori Tsujino 2,4, Kazumasa Horikawa 1, Yasufumi Shigeyoshi 1, Hiroki R. Ueda 2,3,4,5 1 Department of Anatomy and Neurobiology, Kinki University School of Medicine, Osakasayama, Japan 2 Laboratory for Systems Biology, RIKEN Center for Developmental Biology, Kobe, Japan 3 Functional Genomics Unit, RIKEN Center for Developmental Biology, Kobe, Japan 4 Graduate School of Science, Osaka University, Toyonaka, Osaka 5 Department of Mathematics, Graduate School of Science, Kyoto University, Kyoto, Kyoto

P19-10 Influence of cardiac and respiratory artifacts on the relationship between spontaneous EEG and fMRI signals

Objective: Previous studies measured by mismatch negativity (MMN) showed that the auditory information inputted within the temporal window of integration (TWI) was encoded as a single auditory event. The purpose of this study was to investigate the auditory coding in perceptual difference caused by stimuli presentation rates. The lower limits in participants perceived as continuous sound were shorter than 33 ms in SOA. Hence the omission in continuous sound was perceived as a gap event. In contrast, the omission was perceived as an omission event in conditions that were greater than 50 ms in SOA. The MMN and N1 components indicate the omission detection was influenced by the SOA. Methods: Electroencephalogram (EEG) was recorded by using 30 Ag/AgCl electrodes to gap or omission events in sound streams. The stimulus was a burst tone one half of an SOA in duration (rise and fall time 5 ms). Auditory stimuli presented by different conditions of a total of 5 repetition rates (SOA= 12.5, 25, 100, 125 and 200 ms) in separate blocks. The stimulus was omitted once in approximately 2 s randomly from the sound sequence. Results: The large negativity showed at conditions of shorter than 25 ms. There was no negative amplitude in a condition of 200 ms in SOA. The MMN appeared in conditions of 100 ms and 125 ms in SOA. Conclusions: The conditions of sound perceived as continuous low pitch sound elicited large negative amplitude rather than the neural adaptation affected by high presentation rates. This study showed the responses weighted to the right hemisphere regardless of events were omission and gap. It was suggested the same system was activated with the omission and gap. Additionally there was only a difference in saliency indicated by amplitude of a negative component.

Imaging beauty and pleasure: A case study of the hypersonic effect

The search for the source of beauty and desire, of whether it resides in the perceiving subject, has exercised the speculation of philosophers and writers throughout the ages. Both beauty and desire which are directed to the attainment or possession of some objects from which pleasure or satisfaction is expected. We have been investigating the source of beauty and desire for several years, as mechanisms in the brain using a fMRI. Our research is oriented neurobiologically, but is keeping attitude same with previous magnificent philosophers. Kantian question, which are what are the conditions implied by the existence of the phenomenon of beauty and what are the presuppositions that give validity to our esthetic judgments, is especially perspicacious even in attempting by inquiring into whether there are specific neural conditions implied by one or more brain structures. Our special interest is to investigate the general mechanism of beauty and/or desire, which are correlated regardless of stimulus categories, and may reside in only humankind. This talk addresses the mechanism of beauty and desire from the viewpoints of biology of esthetics and humanity.