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Biomedical subjects

F Shima

Publications and source records attributed to F Shima.

At least 55 records · Page 3Linked to original sources
PubMed1988

Alterations in local cerebral glucose utilization during electrical stimulation of the striatum and globus pallidus in rats.

Alterations in local cerebral glucose utilization (LCGU) in conscious rats during electrical stimulation of the striatum and the globus pallidus were investigated using the [14C]deoxyglucose method. Stimulation of the globus pallidus produced a marked contraversive circling behavior, while stimulation of the striatum led only to contraversive head turning. Unilateral stimulation of the striatum increased LCGU bilaterally in the globus pallidus and substantia nigra pars compacta, but only ipsilaterally in the entopeduncular nucleus, substantia nigra pars reticulata and subthalamic nucleus. Similar stimulation of the globus pallidus increased LGCU in the globus pallidus, substantia nigra pars reticulata and compacta, entopeduncular nucleus, subthalamic nucleus, lateral habenular nucleus, parafascicular nucleus of the thalamus, deep layers of the superior colliculus and pedunculopontine nucleus, exclusively on the ipsilateral side. These results indicate that the electrical stimulation induces LCGU changes in the respective structures having both monosynaptic and transsynaptic neuronal inputs. Some changes may also be mediated by antidromic activation. They also suggest that activation of a synaptic process whether excitatory or inhibitory results in increases in LCGU. The bilateral modulatory effects of striatal stimulation may cancel out the circling behavior seen during pallidal stimulation, and cause only head turning.

Animals↗
PubMed1988

Diagnosis and surgical treatment of spasmodic torticollis of 11th nerve origin.

Of 22 patients with spasmodic torticollis, 7 were treated by microsurgical decompression of the 11th nerve. In these patients, there was an intermittent horizontal torticollis characterized by aggravation of the symptoms when in a resting posture, presenting with a striking contrast to the torticollis of extrapyramidal origin that was alleviated while in the resting posture and aggravated by postural stress. A tight neurovascular contact was observed at the C1 level, occurring between the principal 11th nerve and the vertebral or posterior inferior cerebellar artery. Nerve decompression was achieved in 2 by transposing the compressing artery and in 5 by sectioning at C1 or C2 the branching root of the 11th nerve that had caused the tight cross contact by locking the nerve trunk to the dura mater. The symptoms had improved after an interval of 1 to 4 weeks. After an average follow-up of 3 years, full or satisfactory relief had been obtained in 5 and some improvement had occurred in 2 patients. Possible neural mechanisms related to torticollis of 11th nerve origin are discussed.

Accessory Nerve↗
PubMed1987

Altered local cerebral glucose utilization induced by electrical stimulations of the thalamic sensory and parafascicular nuclei in rats.

Alterations in local cerebral glucose utilization (LCGU) induced by electrical stimulation of the sensory relay nucleus (VPL) or parafascicular nucleus (Pf) of the thalamus in conscious rats were measured by the [14C]2-deoxyglucose method, the objective being to assess the mechanism of analgesia induced by electrical stimulations of these structures. Stimulation of the VPL induced an ipsilateral increase in LCGU in the sensory thalamic nucleus itself, the sensory cortex and substantia nigra. Stimulation of the Pf induced bilateral increases in LCGU in the Pf and central medial nucleus of the thalamus, sensory cortex, ventral areas of the striatum and substantia nigra, and ipsilateral increase in LCGU in the periaqueductal gray, parabrachial pontine nucleus and deep layers of the superior colliculus. No significant change in LCGU was detected in the raphe dorsalis, raphe magnus and spinal dorsal horn, in both groups. Our observations coincide with clinical findings that unilateral electrical stimulation of the Pf leads to amelioration of intractable pain bilaterally, while that of the VPL induces an analgesia restricted to the contralateral side.

Animals↗
PubMed1986

Which is responsible for circling behavior in rats, locus coeruleus or dorsolateral pontine tegmentum?

Unilateral electrolytic lesions restricted to the locus coeruleus (LC) in rats did not produce postural asymmetry or circling behavior, while similar lesions in the dorsolateral pontine tegmentum (DLPT) closely ventral to the LC caused a circling behavior toward the contralateral side. The circling behavior was potentiated by intraperitoneal injection of dopamine agonists, apomorphine or methamphetamine, and was abolished by the dopamine antagonist, haloperidol. Neurochemical analysis using a gas chromatographic-mass spectrometric method was made 4, 10 and 20 days after LC coagulation, resulting in a gradual decrease of noradrenaline level in the frontal cortex on the lesioned side. Dopamine content in the striatum in these rats was not significantly affected. Unilateral lesioning of the DLPT produced no significant change in contents of dopamine of homovanillic acid in the striatum or of noradrenaline in the frontal cortex. These results indicate that the LC is not involved in the circling behavior, without a modulatory effect on the dopamine metabolism in the striatum, whereas the DLPT closely ventral to the LC is responsible for circling behavior by subserving as a descending neural pathway conveying striopallidal function on the contralateral side.

Animals↗
PubMed1986

Spasmodic torticollis caused by vascular compression of the spinal accessory root.

A case of spasmodic torticollis in a 27-year-old man cured by vascular decompression of the spinal accessory root, without any nerve sectioning, is presented. The nerve compression was produced by the posterior inferior cerebellar artery originating from the vertebral artery at the C-1 level, and was released by transposing the artery from the nerve root, using the divided dentate ligament. The patient was completely free from symptoms after a follow-up period of 3 years. The possible causal importance of nerve compression in spasmodic torticollis is emphasized.

Accessory Nerve↗
PubMed1985

Altered local cerebral glucose utilization by unilateral frontal cortical ablations in rats.

Alterations in local cerebral glucose utilization (LCGU) following ablations of the unilateral frontal cortex in rats were studied to elucidate the effect of the lesion on the functional activity in the related cerebral structures. Frontal cortical ablations (areas 2, 4, 6 and 10) were made by aspiration on the left side, and LCGU was evaluated at 7 days after the operation, using the [14C]deoxyglucose method. Significant decreases in LCGU in rats with unilateral frontal cortical ablations, were observed in the ipsilateral thalamic nuclei (ventroanterior-ventrolateral (VAL), ventrobasal (VB), reticular), red nucleus and pontine nucleus. The ipsilateral globus pallidus showed a significant LCGU increase. The contralateral cerebellar cortex showed a tendency toward a decrease in LCGU. The striatum, which receives direct projections from the frontal cortex, showed no LCGU change. These results indicated that ablations of unilateral frontal cortex in rats produced LCGU changes in the cerebral structures which have direct or indirect neuronal connections with the ablated area. These LCGU changes were, for the most part, brought about by alteration in the neuronal activity. Particularly, the LCGU increase in the globus pallidus which receives transsynaptic neuronal input from the frontal cortex, without changes in the striatum, which receives direct projection, was attributed to the functional alteration of the globus pallidus produced by the cortical ablation. Destructive lesion of a cerebral structure, therefore, does not necessarily cause functional depressions in the pertinent structures, but it may enhance the function of some structures, depending on the functional characteristics of each neuronal connection and functional organization of those structures.

Animals↗
PubMed1984

Local cerebral glucose utilization altered in rats with unilateral electrolytic striatal lesions and modification by apomorphine.

Alterations in local cerebral glucose utilization (LCGU) in rats with unilateral striatal lesions and the modification by apomorphine were investigated. Electrolytic lesions were made in the rostral part of the right striatum, and 1, 7, and 30 days later, LCGU was observed in terms of relative and absolute LCGU values, using the [14C]deoxyglucose method. A definite change in the pattern of LCGU was seen only at 7 days. These were increases in LCGU in the globus pallidus, entopeduncular nucleus and substantia nigra pars reticulata, and decreases in the ventroanterior-ventrolateral (VAL) and ventromedial (VM) thalamic nuclei and lateral habenula, all on the lesioned side. The circling behavior following the lesion, however, was maximal after 2 days and disappeared after 7 days. Intravenous administration of apomorphine (1.5 mg/kg) produced different modifications in the LCGU pattern between the intact and lesioned sides, at 7 days after producing the lesions. On the intact side, there were increases in LCGU in the striatum, globus pallidus, entopeduncular nucleus, substantia nigra pars reticulata and subthalamic nucleus, and a decrease in the lateral habenula. No such changes were observed on the lesioned side. These results indicate firstly that electrolytic striatal lesions induce LCGU increases or decreases in the structures which receive the striatal input, secondly that the mechanism of this change differs from that of the circling behavior seen in case of striatal lesions, and finally that the majority of the LCGU changes in the basal ganglia and thalamus following intravenous administration of apomorphine are brought about by an altered input of neuronal activity from the striatum to these structures.

Animals↗
PubMed1984

Subcortical, thalamic and cortical somatosensory evoked potentials to median nerve stimulation.

Subcortical and cortical somatosensory evoked potentials (SEPs) to median nerve stimulation were studied in 16 normal controls, 3 patients with Parkinson's disease, and 2 patients with thalamic lesions. Multiple electrodes were placed over the scalp and cervical spines and connected with a hand electrode or Fz in grid II. Thalamic SEPs were recorded directly from the Vim nucleus in 3 patients with Parkinson's disease during the stereotaxic operation. SEPs recorded from the scalp-hand derivations were composed of 4 negative (N9, N11, N16, N18) and 3 positive potentials (P8, P10, P12), whereas, at the scalp-Fz electrode, only one negative peak was identified (N20). N18 is of higher amplitude on the parieto-occipital areas and corresponds to N20. On the other hand, N16 can be identified more clearly on the fronto-central areas at scalp-hand derivations because of intermixture with N18 on the posterior head areas and disappears at scalp-scalp derivation. This suggests that N16 represents a subcortical component that is picked up as a far-field potential at the scalp electrodes. Components preceding N16 at scalp-hand derivations are also interpreted as far-field potentials because of their short latency and wide distribution over the scalp. The peak latency of N16 is not significantly different from the major negativity recorded directly from the thalamus, whereas N18 (N20) occurs significantly later. From this we conclude that N16 is most probably generated in the thalamus with the potentials of shorter latency originating caudal to the thalamus and N18 rostral to the thalamus.

Adolescent↗
PubMed1984

Circling behavior depending on striopallidal and vestibular functions.

Unilateral electrolytic lesions of the pallidum in rats produced circling behavior towards the lesioned side, whereas similar lesions of the fasciculus tegmenti dorsolateralis--including the crossed descending striopallidal and ascending vestibular pathways--evoked circling towards the intact side. Intraperitoneal injections of dopamine agonists, apomorphine or methamphetamine, enhanced the circling in these animals. Unilateral lesions of different parts of the vestibular nuclei per se caused a comparable circling but in opposite directions: Lesions of the superior and lateral vestibular nuclei caused circling towards the intact side, whereas lesions of the inferior and medial vestibular nuclei caused circling towards the lesioned side. In the animals with vestibular lesions, only apomorphine induced tight circling, but methamphetamine did not potentiate circling behavior. Chemical analyses of biogenic amines suggest that unilateral interruptions of the ascending vestibular pathway increase turnover of dopamine metabolism in the striatum on the lesioned side. The findings in the present study suggest that the vestibular function is involved in striopallidal function for circling behavior by modulatingdopamine receptor activity in the striatum.

Animals↗
PubMed1982

Angioma in the paraspinal muscles complicated by spinal epidural hematoma. Case report.

This case of angioma in the paraspinal muscles with extension into the epidural tissue was complicated by epidural hematoma in the thoracolumbar region. The hemorrhage was caused by rupture of the part of the angioma lying in the epidural tissue. A spinal bruit was of great value in diagnosing the angioma. Percutaneous embolization of the feeding arteries of the angioma reduced bleeding during surgery and contributed to successful surgical treatment.

Epidural Space↗
PubMed1978

Clinical studies of the movement-related cortical potential (MP) and the relationship between the dentatorubrothalamic pathway and readiness potential (RP).

In order to investigate the influence of basal ganglia and cerebellar involvement on the preparatory state of the cerebral cortex for voluntary movement, the cortical potential preceding finger movement was studied in 20 patients with Parkinson's disease and 20 patients with cerebellar ataxia. Readiness potential (RP) was abnormal in 90% of the Parkinson group and in 55% of the cerebellar ataxia group. The most frequent abnormality was a depressed amplitude and earlier onset of RP in both groups. The most remarkable finding in the present study was the complete absence of RP with dyssynergia cerebellaris myoclonica (presumed Ramsay Hunt syndrome) whereas normal RP was obtained with cerebellar cortical degeneration. In addition, RP was absent or severely depressed in patients with a unilateral vascular lesion of the midbrain (Benedikt's syndrome) and in patients with Parkinson's disease who underwent unilateral intermedioventral (Vim) thalamotomy. These facts suggest a possible important role of the dentatorubrothalamic or dentatothalamic pathway in the physiogenesis of RP.

Adolescent↗