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Biomedical subjects

H Hirama

Publications and source records attributed to H Hirama.

8 recordsLinked to original sources
PubMed1995

Functional and anatomical fiber analysis of the posterior commissure (PC) in the cat: evidence for PC fibers of which stimulation elicits non-oculosympathetic pupillary dilation.

Pupillary responses were studied by electrical stimulation of the posterior commissure (PC) and the nuclei of origin and termination of PC fibers in the cat. Prior to stimulation experiments, cervical sympathectomy was carried out to study the pupillary responses not mediated by the ocular sympathetic nerve. Pupillary responses were recorded by using an infrared pupillo-analyzing system. The stimulus consisted of a 5 s train of cathodal square wave (0.5 ms duration, 50 Hz) pulses. Stimulation of the PC evoked a pupillary response complex (PRC), which began with a rapid pupillary constriction after the latency of 210-317 ms. The threshold of constriction was 10 or 20 microA. Constriction reached its peak shortly after the onset of the stimulus, then the pupil gradually re-dilated (pupillary escape, PE) even though the stimulus was still lasting. The pupil gradually returned, after stimulus termination, to the size before stimulation in the cases with the pupil area before stimulation larger than 20 mm2. On the other hand, in the cases with smaller pupil area before stimulation (< 20 mm2), rapid constriction and PE were followed, after stimulus termination, by a large dilation (after-dilation, AD). The thresholds of PE and AD were 20 or 40 microA. Pupillary constriction was evoked with a large range of stimulus frequency (1-100 Hz). To evoke PE and AD, stimulus frequencies of 10 and 50 Hz were required respectively, and lower frequencies were ineffective. The peak latency of AD increased in proportion to the increase in stimulus frequency and intensity. Following horseradish peroxidase (dissolved in 5% alkyl-phenol ethylene oxide) injection into the pretectal region where fibers from the PC fan out, retrogradely labeled neurons occurred in many subthalamic, pretectal and midbrain nuclei on the other side. They were classified into three groups in terms of the pupillary response evoked by electrical stimulation; the pupillo-constrictory nuclei (PCNs) of which stimulation evoked constriction with the threshold of 20 microA, the pupillo-dilatory nuclei (PDNs) of which stimulation evoked dilation with the threshold of 20 or 10 microA, and other nuclei with higher thresholds of constriction or dilation. The PDNs were further, classified into two groups (Type 1 and Type 2 PDNs) according to the relationship between stimulus intensity and the peak latency of dilation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1987

Colleges and universities should not be responsible for level II fieldwork education.

The scheduling and managing of Level II fieldwork education which is required for the certification of the occupational therapy assistant and occupational therapist are time-consuming, financial burdens to the colleges and universities, the training facilities, and the student. A more efficient procedure with advantages for all parties concerned is suggested. Level II fieldwork education should be a postgraduate experience arranged outside of the jurisdiction of the degree-granting educational institution.

Clinical Clerkship↗