An Experimental Study of Stable Operating Conditions for a High-Sensitivity Induction Gradiometer

Stable operating conditions for a high-sensitivity induction gradiometer are studied experimentally. In order to reduce electrical interferences in our developed induction gradiometer, we construct a Faraday cage. It consists of copper mesh and wood, and is 2.0 m x 1.8 m x 1.8 m in size. Experimental results show that the inside of the cage can provide a quiet electrical environment where the electrical interference is suppressed. Choosing a suitable grounding point for the electronics, undesirable signals in the sensor output are cleaned. Observation of a weak magnetic field is also demonstrated.ArticleIEEE TRANSACTIONS ON MAGNETICS. 45(6):2784-2787 (2009)journal articl

Acetyl-L-carnitine enhances myelination of regenerated fibers of the lateral olfactory tract

It is well known that acetyl-L-carnitine (ALC) has various neuroprotective effects against neurodegenerative diseases. In addition, it has been reported that ALC facilitates myelination of regenerated axons after peripheral nerve injuries. We previously reported that spontaneous regeneration of the lateral olfactory tract (LOT), the main fiber tract of the central olfactory system, consistently occurred in newborn rats and a majority of these regenerated fibers were unmyelinated in neonatally LOT-transected young adult rats. To investigate the effects of ALC treatment on myelination in LOT, neonatal rats were treated with ALC after LOT transection. Immunohistochemistry for myelin basic protein showed more positive areas in ALC-treated rats than in control rats. Moreover, the number of myelinated axons of regenerated fibers was assessed using electron microscopy and was found to be statistically higher in ALC-treated rats compared to control rats. The study revealed that ALC accelerates myelination of regenerated fibers in neonatally LOT-injured young adult rats. (C) 2017 Elsevier B.V. All rights reserved.ArticleNEUROSCIENCE LETTERS.653:215-219(2017)journal articl

Neural Plasticity of Neonatal Hypoglossal Nerve for Effective Suckling

“This is a preprint of an article published in JOURNAL OF NEUROSCIENCE RESEARCH 2007; 85(11): 2518-2526”ArticleJournal of Neuroscience Research. 85(11): 2518-2526 (2007)journal articl

Functional correlation between olfaction and various sectioning of the lateral olfactory tract

信州大学博士（医学）・学位論文・平成24年3月31日授与（甲第915号）・関口泰之The lateral olfactory tract (LOT) is a central olfactory pathway, and efferent projections from the olfactory bulb are conveyed to the olfactory-related cortical structures via the LOT. The purpose of the present study is to determine the exact site of the LOT causing functional impairment in animals. After ablation of the right olfactory bulb, rats received rostrocaudal transection injuries on the left LOT at different levels between the olfactory bulb and the middle cerebral artery. Olfactory function of LOT-transected rats was studied by examining their olfactory ability to discriminate between the smell of water and cycloheximide solution, a strong repellent for rodents. Rats were divided into two groups based on their olfactory discriminative abilities. The olfaction positive (+) group achieved 83% +/- 1% correct responses and the distances of the LOT-transected sites from the middle cerebral artery of this group ranged between 0.8 and 2.4 mm (n = 8). The olfaction negative (-) group achieved 48% +/- 1% correct responses and the distances of the LOT-transected sites from the middle cerebral artery ranged between 2.5 and 4.2 mm (n = 10). From these data, we concluded that the site of the LOT critical for olfactory function is located approximately 2.5 mm from the middle cerebral artery. (c) 2012 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.ArticleNEUROSCIENCE RESEARCH. 73(1):17-23 (2012)journal articl

Analysis of spontaneous regeneration of olfactory structures with emphasis on myelination and re-innervation of cortical areas

Regeneration of the lateral olfactory tract (LOT) occurs spontaneously after transection in developing rats. In neonatally LOT-transected rats, we observed a newly formed myelinated tract near the rhinal sulcus. The aim of this study was to analyze the precise re-innervated cortical areas and to demonstrate ectopic LOT myelination in neonatally LOT-transected rats. Neonatal rats were subjected to unilateral LOT transection and simultaneous injection of a retrograde fluorescent tracer into the posterior olfactory cortex to evaluate the degree of transection. After 8 weeks, bilateral olfactory bulbs of the rats were subjected to multiple injections of an anterograde neuronal tracer to determine the extent of the regenerated fibers. In the completely LOT-transected rats, the regenerated fibers were distributed in the anterior olfactory cortices: the anterior olfactory nucleus, the olfactory tubercle, and the rostral part of the piriform cortex. Ectopic myelination of LOT was evident immediately below the rhinal sulcus in the completely and incompletely LOT-transected rats. We concluded that the regenerated bulbar fibers were confined to the regions of the anterior olfactory cortices and that ectopic myelination of the regenerated LOT occurred only at a specific site near the rhinal sulcus.ArticleNEUROSCIENCE LETTERS. 537:35-39 (2013)journal articl

Effects of repeated crush injuries on motor functional recovery of the sciatic nerve

信州大学博士（医学）・学位論文・平成25年1月30日授与（乙第1153号）・伊坪 敏郎Objectives: The present study was conducted to examine whether repeated crush injuries have significant effects on motor functional recovery of peripheral nerves. Methods: Repeated crush injuries of the sciatic nerve were inflicted on adult rats at 1-week intervals, and functionality of the sciatic nerve was assessed by the static sciatic index each week for 8 weeks after the final injury. To determine the effects of repeated crush injuries on motor functional recovery of the sciatic nerve, tibialis anterior muscle fibers from single and triple crush injuries were examined, and fiber size and fiber reinnervation during the 2- to 4-week period after the final injury were measured. Results: Compared to single crush injuries, which completely recovered by post-injury week 4, double crush injuries resulted in retarded, but complete recovery by post-injury week 6, whereas triple crush injuries resulted in marked retardation in the regenerative process with incomplete recovery during week 8 of the experimental period. Muscle fiber size for rats with triple crush did not recover to normal range at post-injury week 4, despite its normal size for rats with single crush. The rate of reinnervation increased prominently between post-injury weeks 2 and 3 in both injuries, but the rate with triple crush was lower than that with single crush at post-injury week 3. Discussion: These results, which contradict those of a previous study that reported early functional recovery, indicate that repeated crush injuries inhibit motor functional recovery of the damaged sciatic nerve, as evidenced by delayed and incomplete regeneration, atrophied muscle fibers, and delayed reinnervation.ArticleNEUROLOGICAL RESEARCH. 34(9):908-914 (2012)journal articl

神経伝達物質と嗅覚機能

金沢大学医学部嗅球におけるセロトニンの働きを調べるため、ラットで嗅球に投射するセロトニン線維を神経毒を用いて選択的に障害し嗅覚に与える影響を行動学的並びに組織学的に検討した。ナラマイシンを用いて嗅覚条件づけ学習を行い正解率が100%になった後、嗅球に直接または脳幹の縫線核にある細胞体から嗅球へセロトニン線維が投射する途中の経路である内側前脳束にセロトニン神経毒である5,7-dihydroxytryptamine(5,7-DHT)を注入した。注入後ナラマイシンを用いて経時的に嗅覚機能を調べた。なお5,7-DHT注入群は嗅球のセロトニン線維の障害の程度により完全障害群と不完全障害群に分類した。結果、(1)完全障害群は行動実験にて5,7-DHT注入直後の3日には嗅覚機能は正常であるが、注入後14〜28日には無嗅覚の状態となった。(2)5,7-DHTはセロトニン線維にほぼ特異的に作用し、他のモノアミン線維(ノルアドレナリン、ドーパミン)への直接の影響は小さかった。(3)嗅球の大きさは縮小し本来セロトニン線維が密に分布している糸球体は著明に萎縮していた。(4)嗅上皮は著明に萎縮し、嗅細胞は減少または完全に消失していた。(5)不完全障害群では明らかな行動学的、形態的異常を認めなかった。以上の結果から、嗅球での長期にわたる著明なセロトニンの低下は一次感覚ニューロン(嗅細胞)の嗅上皮内の細胞体もしくは嗅球糸球体内の軸索終末のいずれかに変性をもたらし、著しい嗅覚機能低下をきたすことが明らかになった。脳内の特定の伝達物質の欠損によって嗅覚障害がおこるという報告はなく、嗅覚障害の1つの新しいメカニズムを提起できるものと思われる。研究課題/領域番号:05807157, 研究期間(年度):1993出典：研究課題「神経伝達物質と嗅覚機能」課題番号05807157（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-05807157/）を加工して作

大脳基底核神経回路網の研究(視床下核ニューロンの投射様式と投射線維終末について)

金沢大学医学部研究課題/領域番号:63770040, 研究期間(年度):1988出典：研究課題「大脳基底核神経回路網の研究(視床下核ニューロンの投射様式と投射線維終末について)」課題番号63770040（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-63770040/）を加工して作