Keiichiro Uchi

Somatosensory evoked magnetic fields elicited by dorsal penile, posterior tibial and median nerve stimulation

The aim of this study is to localize the primary sensory cortex of urogenital organs in the human brain. Using a newly developed MRI-linked magnetoencephalography system, we measured somatosensory evoked magnetic fields (SEFs) for unilateral stimuli on the dorsal penile nerve (DPN), posterior tibial nerve (PTN) and median nerve (MN). In five healthy male subjects, SEFs were clearly observed. Peak latency of the first cortical components were 63.8 +/- 9.2 ms for DPN, 39.8 +/- 3.0 ms for PTN and 20.7 +/- 0.7 ms for MN stimuli. Peak amplitude of the first cortical components were 63.1 +/- 10.8 fT for DPN, 160.2 +/- 50.1 fT for PTN and 335.2 +/- 70.3 fT for MN stimuli. Isofield map for the peak latencies indicated a single dipolar pattern for DPN as well as for PTN and MN stimuli. Using a single current dipole model, all SEF sources were localized on the contralateral central sulcus to the stimuli, indicating the primary sensory cortex. The DPN sources were localized on the interhemispheric surfaces, corresponding to previous speculations by direct cerebral stimulation. This non-invasive SEF technique promises further brain functional mapping for the urogenital organs.

Bulbocavernosus reflex during the micturition cycle in normal male subjects

Abstract Background:  To investigate normal changes in the bulbocavernosus reflex (BCR) during the micturition cycle, we examined the change in BCR during the micturition cycle using an evoked potential reaction of the BCR (BCR‐EP).

Artificial Urethral Valve Using SMA Actuators. Improvement of Urethral Valve and Introduction of Transcutaneous Energy Transmission System.

This paper is concerned with the development of an artificial urethral valve for treating urinary incontinence, which is driven by shape memory alloy actuators. Three types of valves are assembled and their opening and closing functions are examined experimentally by using the urethrae of male dogs. The latest model is driven by the non-contact induction heating system using power transmission coils. It is found that all of them show good opening and closing functions. The energy to drive the valve is transmitted by using an implanted coil of which outside diameter is 60 mm.