Yasumasa Okada

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The characteristics of GABAergic neurons involved in respiratory control have not been fully understood because identification of GABAergic neurons has so far been difficult in living tissues. In the present in vitro study, we succeeded in analysing the electrophysiological as well as morphological characteristics of GABAergic neurons in the pre-Bötzinger(More)
We developed a dual oscillator model to facilitate the understanding of dynamic interactions between the parafacial respiratory group (pFRG) and the preBötzinger complex (preBötC) neurons in the respiratory rhythm generation. Both neuronal groups were modeled as groups of 81 interconnected pacemaker neurons; the bursting cell model described by Butera and(More)
The high cost of digital echocardiographs and the large size of data files hinder the adoption of remote diagnosis of digitized echocardiography data. We have developed a low-cost digital filing system for echocardiography data. In this system, data from a conventional analog echocardiograph are captured using a personal computer (PC) equipped with an(More)
BACKGROUND Anisotropic conduction properties may provide a substrate for reentrant arrhythmias. We investigated the age-dependent changes of structural and functional anisotropy in isolated right atria from infant (1 to 2 months), young (6 to 12 months), and old (6 to 10 years) dogs. METHODS AND RESULTS The histology of the mapped atrial tissues (a small(More)
Two putative respiratory rhythm generators (RRGs), the para-facial respiratory group (pFRG) and the pre-Bötzinger complex (preBötC), have been identified in the neonatal rodent brainstem. To elucidate their functional roles during the neonatal period, we evaluated developmental changes of these RRGs by optical imaging using a voltage-sensitive dye. Optical(More)
We reviewed the previous reports on the fine anatomy of the mammalian ventral medulla with special attention to the cytoarchitecture of the superficial chemosensitive regions to summarize what is known, what is not yet known, and what should be studied in the future. We also reviewed studies on anatomical relationship between neurons and vessels, and(More)
It has been postulated that there exists a neuronal mechanism that generates respiratory rhythm and modulates respiratory output pattern in the high cervical spinal cord. Recently, we have found a novel respiratory neuron group in the ventral portion of the high cervical spinal cord, and named it the high cervical spinal cord respiratory group (HCRG). In(More)
The pre-Bötzinger complex (preBötC) of the ventrolateral medulla is the kernel for inspiratory rhythm generation. However, it is not fully understood how inspiratory neural activity is generated in the preBötC and propagates to other medullary regions. We analyzed the detailed anatomical connectivity to and from the preBötC and functional aspects of the(More)
Extracellularly released adenosine triphosphate (ATP) modulates sensory signaling in the spinal cord. We analyzed the spatiotemporal profiles of P2X receptor-mediated neuronal and glial processing of sensory signals and the distribution of P2X receptor subunits in the rat dorsal horn. Voltage imaging of spinal cord slices revealed that extracellularly(More)
The anatomical structure of central respiratory chemoreceptors in the superficial ventral medulla of rats was studied by using hypercapnia-induced c-fos labeling to identify cells directly stimulated by extracellular pH or PCO(2). The distribution of c-fos-positive cells was found to be predominantly perivascular to surface vessels. In the superficial(More)