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Physiology 2

  • Osamu Miyamoto, M.D & Ph.D.

Main Areas and Themes of Research

The main subject areas investigated in our laboratory are pathophysiology in neurological disorders and signal transduction mechanisms in the nervous system. Ongoing research projects include:

1) Neuropathophysiology in cerebral ischemia and epilepsy

The mechanisms of brain damage in neuropathological conditions such as cerebral ischemia and epilepsy are investigated with a focus on glutamate and oxygen radicals using animal models. The mode of action of ischemic tolerance is also investigated with a view to developing novel treatment strategies.

2) Effects of physical exercise following cerebral ischemia

We make an animal model of multiple cerebral infarctions by the injection of microspheres, and study the effects of physical exercise on the recovery of motor and memory function after infarction.

3) Role of Ca2+ on synaptic plasticity

Use-dependent activation of Ca2+-induced Ca2+ release (CICR) via ryanodine receptors (RyRs) in the nerve terminals is unique and greatly amplifies transmitter exocytosis. The localization of RyRs at synapses and the role of CICR on synaptic plasticity are investigated by electrophysiological and histological examinations in frog motor nerve terminals.

4) Remapping of the motor cortex after infarction

The primary motor cortex is somatotopically organized. From dorsomedial to ventrolateral, movements are elicited progressively from the torso, arm, hand, and face. The representations of body parts that perform precise, delicate movements, such as the hands and face, are disproportionately large compared to the representations of body parts that perform only coarse, unrefined movements, such as the trunk or legs. It is known that the mapping of the primary motor cortex is changed after the neuropathological events like cerebral infarction. The mechanisms of the changes in the motor mapping and the influence of the rehabilitation are investigated.

5) Stem cells of olfactory mucosa for transplantation therapy

Olfactory mucosa (OM) is a useful source for cell transplantation since neurogenesis continues throughout adult life in the human OM, providing an accessible source of stem cells. Olfactory ensheathing cells (OEC) which secrete neurotrophic factors such as NGF and GDNF are also present in OM. We are trying to differentiate OM stem cells into dopaminergic or GABAergic neurons, and transplant them with OEC to the Parkinson’s disease or epilepsy model animals.

Educational Features

The human body consists of billions of cells that are organized into tissues and organ systems. In a healthy person, these tissues and organ systems function and cooperate with each other in such a way as to sustain life. The essence of Physiology is to study these biological functions and their mechanisms, and knowledge of Physiology is essential for medical students. A familiarity with the structure of organs is also required to understand organ functions. Individual organ systems are discussed in lectures which build on the Anatomy lectures provided in the first year, and lectures relating to the functional interaction of cells or organ systems are mainly provided in the second year. In these lectures, the Physiology 2 course provides instruction on cellular physiology, membrane physiology and the nervous system (i.e. synaptic transmission, sensory system, motor function, higher brain function and autonomic nervous system). The principles of physiology are further demonstrated in practice when students participate in 6 physiological practical subjects in the second year and 3 practical subjects as part of the Physiology 2 course (i.e. action potential of neurons, somatic sensation and electroencephalogram).

Through the learning of Physiology, we hope that students become acquainted with the variety of processes that occur in the human body for maintaining homeostasis, and that students are capable of considering the mechanisms of disease when seeing patients as a clinician in the future.