Toshikazu Shinba

By Toshikazu Shinba

This chapter on heart rate variability (HRV) presents a view based on our published data that HRV profiles in depression and anxiety show differences and can be used for the differentiation of these two disorders in clinical practices. Characteristic HRV profiles in depression and anxiety are revealed by measurements incorporating task load. Analysis of two frequency-domain HRV parameters, low frequency (LF) and high frequency (HF), together with heart rate (HR) itself measured at rest (Rest), during the task load (Task), and at rest after the task (After) enables the evaluation of the autonomic regulation in response to behavioral changes with different stress levels. LF is the heart rate modulation related to blood pressure changes to stabilize circulation. HF is related to breathing rhythm and reflects parasympathetic activity. It has been indicated that LF, HF, their ratio LF/HF and HR in depression and anxiety show characteristic dysregulations during Rest, Task and After. These HRV profiles are useful for understanding the pathophysiology of the disorders.

Part of the book: Biosignal Processing

By Toshikazu Shinba

The present chapter summarizes the functional perspectives of endogenous static and extremely low-frequency electric fields generated in the body of humans and rodents and discusses the possibility of ephaptic interaction. The electric field recorded on the head surface (electroencephalogram) exhibits μV-range amplitude, which is not significantly affected by the brain size. The surface potential is small, but the electric field inside the brain is regionally localized and exhibits an intensity of around 1 V/m. Electric fields with a similar intensity are present in the muscle and skin. These observations suggest that the endogenous electric field shows complex patterns of distribution inside the body. Furthermore, endogenous electric field profiles are influenced by externally applied electric field. Event-related field potentials in the human and rat brain are altered by concomitant static electric field treatment, and externally applied extremely low-frequency electric field induces an increase in electroencephalogram power. These findings would support the presence of ephaptic interaction, which may be related to the modulation of physiological function. Although further research is necessary, an endogenous electric field can serve as a form of interactive information to integrate physiological activities.

Part of the book: Electrostatics - Fundamentals and Modern Applications [Working title]