Yoshihisa Nakai

Influence of norepinephrine-containing neurons derived from the locus coeruleus on lateral geniculate neuronal activities of cats

Abstract Facilitatory influences of conditioning stimulation of LC on evoked potentials in LGN to OTS were demonstrated in cats. These influences were observed when the stimulating electrode had been placed in areas histologically ascertained as having NE-containing cell bodies. The coeruleus modulation of geniculate potentials was not observed after reserpine pretreatment. However, a rapid recovery of the facilitation was produced by an l -dopa or NE injection. Injection of fusaric acid, a potent dopamine-β-hydroxylase inhibitor, also decreased the LC effects. In these cats, only an intraventricular NE injection was effective for the coeruleus modulation. The responsiveness of relay neurons to OTS, studied by extracellular recordings, was also enhanced y LC stimulation. Type-A interneurons, which responded to both orthodromic and antidromic stimulation, received influences similar to those on relay neurons after LC stimulation. Type-B interneurons, which failed to respond by antidromic spike discharges, received depressive effects. In reserpine-pretreated cats, LC effects on neuronal activities in the LGN were not observed. In these cats, l -dopa injection was effective in restoring the coeruleus modulation. It is suggested from these findings that enhanced responsiveness of relay neurons is due to an inhibitory effect on type-B interneurons after activation of NE-containing neurons derived from the LC.

The mechanism of antagonism between apomorphine and metoclopramide on unit discharges from nuclear structures in the brainstem of the cat

Abstract Effects of apomorphine and metoclopramide were studied on the spontaneous unit discharges in the single neurons of nuclear structures of brainstem in the ence´phale isole´preparations of cats. Apomorphine increased significantly the spontaneous discharge frequencies of single neurons in the Nucleus tractus solitarii, but did not influence the frequencies in the Nucleus vestibularis lateralis and Nucleus sensorius superior n. trigemini and the number of spikes per volley in the inspiratory unit discharges. Metoclopramide decreased significantly the firing rate of unit discharges in the Nucleus tractus solitarii and Nucleus vestibularis lateralis, while the unit discharges of the Nucleus sensorius superior n. trigemini and the rhythmic unit discharges corresponding to inspiration were not modified by metoclopramide. The acceleration of spontaneous discharge frequencies of the Nucleus tractus solitarii induced by apomorphine was completely blocked by the supplement of metoclopramide. Metoclopramide prevented retching and vomiting elicited by electrical stimulation of the Nucleus tractus solitarii. In some animals, metoclopramide produced a transient alert pattern in the cortical and hippocampal EEG and depressed slightly the recruiting response. However, it did not affect the reticular arousal response and the evoked click potentials in the auditory cortex.

Analysis of evoked responses in the visual pathway of cats with elevation of the intraocular pressure

Abstract Effects of temporary elevation of the intraocular pressure (IOP) on the evoked responses to optic tract stimulation in the lateral geniculate nucleus, superior colliculus and visual cortex were investigated in unanesthetized cats. No significant increase in the visually evoked responses was observed at an IOP elevation up to 80 mm Hg. On the other hand, an IOP elevation higher than 120 mm Hg produced a marked increase in the evoked responses. A significant increase was found particularly in the radiation response of the lateral geniculate nucleus, the negative wave of the superior colliculus and the P3, P4 and N waves of the visual cortex. Reticular facilitation of the visually evoked responses was still present during the elevation of IOP, although the increasing rate of amplitude was slightly reduced. Pentobarbital and ethanol did not affect the potentiation of the visually evoked responses caused by the elevated IOP.

Bell's palsy and pupillary response.

Pupillary response was measured with binocular pupillogram to analyze Bells palsy through examination of autonomic nerve function. This analysis was performed in 166 patients of Bells palsy who consulted within one month after onset. Based on the results of pupillary response measurement, autonomic nerve function was normal in 54 patients, and abnormal in 46. The delayed recovery was found in the abnormal group more often than in the normal group. In the abnormal group, patients with fast recovery were older than fifty, while those with delayed recovery were younger than forty-nine.

Analysis of Associated Movements in Recovery Process of Peripheral Facial Palsy

1) 末梢性顔神麻痺後遺症としてもっとも多い病的共同運動を定量的に分析するため, Medelec 製筋電計に積分モジュールを使用し, 惹起された病的共同運動を積分波形として記録し測定した.2) すなわち, 顔面諸筋の生理的共同運動量の範囲の設定, 測定装置の noise 量を判定することが容易なため, 病的共同運動を正確に定量化することができた. そのため検査対象各種筋群の経時的病的共同運動量, あるいは各筋群間の比較が容易となった.3) 共同運動は, 健康側の前頭筋, 眼輪筋および口輪筋からも記録できたが, それぞれの筋電図の積分モジュールによる reset count はほとんど0～5回の範囲に分布した.4) 病的共同運動は眼輪筋がもっとも高頻度 (57%) で記録され, ついで前頭筋 (53%) および口輪筋 (47%) の順で記録された. 病的共同運動の引き金となる顔面表情運動は口を「ウー」とする運動がもっとも高率で79%に達した.5) 本稿で述べた方法は, 病的共同運動を定量的に記録できるため, 病的共同運動の早期発見, 経時的変遷および治療効果の判定などにきわめて有用な情報を提供できる.