Miyoshi Urabe

Inhibitory effects of the limbic system on the nucleus centrum medianum of the thalamus

Abstract Evoked potentials in cat centrum medianum (CM) produced by splanchnic nerve stimulation were decreased in amplitude by repetitive stimulation of the amygdala. Response patterns of CM single unit discharges evoked by splanchnic nerve stimulation were classified into four types; general, suppression, tonic activation, and reverberation. An attempt was made to determine the basis for each type of pattern and results were explained in terms of synaptic mechanisms.

RELATION OF BRAIN STEM ACTIVITY TO THE EVOKED POTENTIAL IN THE SPINAL CORD FOLLOWING THE SINGLE VOLLEY OF THE SPLANCHNIC NERVE

In an experimental study of the brain stem mechanism influencing motor activity, conducted by Magoun et a1 in 1944, the stimulation of the bulbar reticular formation was found both to inhibit and to facilitate movements. Since then, many authors have performed studies on the aspect of activities of the reticular formation. The most significant research among them which most impressed us was the one of Hagbarth & Kerr (1954). It was found by them that the descending connections of the reticular formation system had an inhibitory influence on the somato-sensory as well as the specific sensory such as optic and auditory activities. However, no study was published by the previous worker on the inhibitory or facilitatory mechanism of afferent activity of the splanchnic nerve which presumablly plays a major role in viscero-sensory system. The present authors have attempted to observe how the stimulation of the medulla, pons and midbrain had influence upon the afferent impulse in the spinal cord subsequent to the stimulation of the splanchnic nerve, in order to clarify the mechanism of perception of the viscero-sensory activity.

Studies of the activities of vagal afferents in the medulla oblongata and thalamus with special reference to a central regulatory mechanism

Abstract This report is concerned with projections of the vagal afferents in the mes- and diencephalon and the central regulation of their evoked activity particularly in the nucleus tractus solitarius.

INFLUENCE OF THE AFFERENT IMPULSE OF THE PERIPHERAL NERVES ON THE SPLANCHNIC AFFERENT IN THE ANTEROLATERAL FUNICULUS OF THE SPINAL CORD

Evoked potentials to the splanchnic stimulation were recorded from the ipsi‐lateral posterior funiculus and from the bilateral anterolateral funiculi in the spinal cord. The former had a short latency and the latter had a long latency. Evoked potentials of the splanchnic nerve were recorded from the nucleus cuneatus and lemniscus medialis in the medulla, which had a short latency since their origin was in the impulses ascended through the posterior funiculus of the spinal cord. Evoked potentials were also recorded from the tractus spino‐m‐thalamicus and nucleus reticularis ventralis in the medulla, which had a long latency corresponding with those from the anterolateral funiculi of the spinal cord.

5. Studies on the Sensory Pathway of the Vagal Nerve III

In previous studies (I), (II), based on the degeneration experiment using mostly dogs, we reported the new pathway which passed through the solitary tract at the level of the entrance of the rootlets of glossopharyngeal and vagal nerves and extended dorsally along the lateral border of the basal gray matter. In present study, we examined these fiber groups and their relation to the ascending pathways of the spiral cord using monkeys which are most closely related to man. Using 7 Japanese monkeys, the cuttings of the vagal nerve at the portions below nodose ganglion, between nodose and jugular ganglions and in the cranium, were performed. Furthermore, the contralateral anterolateral chordotomy and hemisection of the spinal cord were added to some of them at the thoracal and lumbal portions. Secondary degenerations were observed by Marchis serial sections. In Japanese monkeys, there is no degeneration in the medulla subsequent to the infranodose section of vagal nerve. On the other hand, in the cutting of the vagal nerve at the portion between nodose and jugular ganglions, it was confirmed that new degenerative fiber groups similar to those of dogs appeared in the transverse and longitudinal sections. The degenerative fibers were also recognized in nearly similar degrees in the intracranial sections of the vagal rootlets. There was no direct relation between this pathway and the ascending pathways of the spinal cord.