Studies on neurotransmitter markers and striatal neuronal cell density in Huntington's disease and dentatorubropallidoluysian atrophy

Neurotransmitter abnormalities in the basal ganglia of individual "choreic" patients (9 cases of Huntington's disease-HD and 3 cases of dentatorubropallidoluysian atrophy-DRPLA) and 14 normal controls were investigated. Choline acetyltransferase activity in the striatum was decreased in approximately half the "choreic" patients. GABA concentration in the substantia nigra or in the globus pallidus was decreased in all "choreic" cases except one case of DRPLA. Substance P concentration was also reduced in the same nuclei as GABA except in one case of HD. These findings imply: cholinergic, GABAergic or substance P-related markers found in the basal ganglia of HD are not disease-specific but also found in the other "choreic" disorder, i.e. DRPLA; most prominent biochemical changes in HD would be a decrease of GABA in the basal ganglia. Correlation analysis of the markers in the basal ganglia and the striatal neurone densities of "choreic" patients (5 cases of HD and 3 cases of DRPLA) and 7 normal controls yielded positive correlation between GABA concentration in the substantia nigra and the globus pallidus, and the neuronal cell density in "small" cells in the striatum of normal control and HD. Positive correlation between substance P concentration and the striatal neurone density was only found in the substantia nigra. Choline acetyltransferase activity in the striatum was found to be positively correlated with the density of "large" cells in the striatum rather than that of "small" cells. In DRPLA there was no direct correlation between the values of the markers in the basal ganglia and the striatal neurone density. The decrease of transmitter markers without striatal cell loss in this particular choreic disorder could be regarded as a sequence of "biochemical degeneration" of striatal neurones. Based on these findings, the underlying mechanisms of choreic involuntary movements were briefly discussed.

Hippocampal EEG changes in rats following cerebellar lesions

In the rat, there is a close relation between hippocampal theta rhythm and voluntary movements. The purpose of the present study was to investigate whether motor deficits and subsequent recovery following cerebellar lesions may be accompanied by changes in hippocampal EEG. The results show that rats with severe motor dysfunctions displayed increased frequency of hippocampal theta that lasted beyond the recovery of motor deficits. Hippocampal theta that appeared along with gross automatic movements disappeared about 50 days postoperatively. The findings are discussed in terms of recovery of function and potential compensatory neural mechanisms.

Recent development of the study on clinical significance of abnormal eye movement

As a general trend, the diagnosis in medical clinics often depends on laboratory test results. Neurotological diagnosis, however, requires detailed neurological examinations on a patient by a neurotologist. Therefore, there are differing diagnostic skills among physicians, and there is a kind of "man-made flavor" in neurotological diagnostic procedure. In the present study, current development in the knowledge on the clinical diagnostic significance of pathological eye movement during the last 2-3 years is summarized. Acquired pendular wondering eye-movement. Fixation jerks. Spontaneous and transitory eyeball burst or seizure. Vertical rebound nystagmus. Optokinetic vertical ocular dysmetria. Divergence nystagmus. Counterolling, pure rotatory positioning nystagmus. Inversion of optokinetic after-nystagmus (OKAN). Vertical congenital nystagmus and inversion of optokinetic nystagmus (OKN). Treatment of congenital nystagmus. Vertical spontaneous nystagmus to lower eyelid or so-called "downbeat nystagmus." Downbeat nystagmus seen in bilateral labyrinthine dysfunction. The significance of bilateral vestibular lesion, or symmetric lesion in other is emphasized in the present report for reader's reference and criticism. Our experience on the clinical significance of the abnormal eye movement was reported. It is our wish that accumulation of data on important cases along with the results of experimental studies directly connected with clinical medicine may contribute to the progress of our neurotology in the right direction as "neurology of the posterior fossa."

DDT myoclonus: sites and mechanism of action

Intragastric injection of the insecticide DDT produces a stimulus-sensitive myoclonus in mice and rats. Unilateral stereotaxic infusions of DDT into rat medullary reticular formation also induced generalized myoclonus, identical to that produced by systemic administration. Similar myoclonus, but of lesser intensity, occurred when DDT was injected into cerebellar nuclei, red nucleus, and the inferior olive. Multiple other regions of the brain were resistant to the myoclonic action of locally infused DDT. Direct infusions into the medullary reticular formation of allethrin, which has a similar action on neuronal membranes as DDT, or the glycine receptor antagonist, strychnine, also elicited myoclonus.

Autosomal dominant idiopathic hypoparathyroidism and nervous system dysfunction: report of three cases and review of the literature

The neurological manifestations of idiopathic hypoparathyroidism in a father, his son, and his daughter are reported. In all three epilepsy was the first manifestation of the disease. Father and son also showed mental deterioration and striocerebellar symptoms; their CT scans revealed symmetrical calcification in the basal ganglia and dentate nuclei. The extent of this calcification increased during normocalcemia, which was produced by dihydrotachysterol therapy. This indicates that other factors than merely hypocalcemia influence the intracerebral calcifying process. Somatosensory evoked potentials (SSEP) showed an abnormal nonspecific complex, indicating dysfunction of the cortical gray matter. It is suggested that in the evaluation of idiopathic hypoparathyroidism one also must be beware of the possibility of epilepsy, mental deterioration, striocerebellar symptoms, intracerebral calcification and SSEP disturbances.

Cardiovascular effects of beta-endorphin after microinjection into the nucleus tractus solitarii of the anaesthetised rat

The cardiovascular effects of beta-endorphin after administration directly into the nucleus tractus solitari (NTS) of urethane-anaesthetised rats were investigated. Unilateral injection resulted in a U-shaped dose-response relationship with a fall in mean arterial pressure and heart rate occurring at low doses (less than 10 ng). No change in respiratory frequency was observed at any of the doses examined. The hypotensive effects of beta-endorphin were anatomically specific and restricted to the NTS. The depressor response was prevented and bradycardia reduced by naloxone (1 mg/kg s.c. or 10 ng injected into the NTS) and also by beta-endorphin antiserum (1:50 dilution) but not by antiserum to [Met5]enkephalin (1:50 dilution) applied locally into the NTS. The beta-endorphin antiserum caused a rise in blood pressure when administered alone. Conversely microinjection of antiserum to [Met 5]enkephalin resulted in a brief depressor response. Doses of beta-endorphin larger than 10 ng induced a rise in blood pressure accompanied by variable effects on heart rate. Similarly unilateral administration of Des-tyr-endorphin (100 pg) resulted in a blood pressure increase and [D-Ala2,Met5]enkephalin produced a dose-related pressor response and tachycardia. The results indicate that at least two separate endorphin systems are involved in cardiovascular control at the level of NTS, one being depressor in nature (beta-endorphin-like) and the other pressor ([met5]enkephalin-like).

The reticulocerebellar projection in the cat as studied with retrograde transport of horseradish peroxidase

Injections of horseradish peroxidase into the various parts of the cerebellar cortex and the cerebellar nuclei in the cat result in labelled cells within the reticular formation proper. All the reticular nuclei (with the exception of the reticular formation of the mesencephalon) send fibres to the cerebellum. The highest number of labelled neurons after cerebellar injections is found in the caudal reticular formation, especially within nucleus reticularis ventralis, nucleus reticularis lateralis and nucleus reticularis gigantocellularis. Another region for an accumulation of labelled cells is the rostral part of nucleus reticularis pontis caudalis. Except for the paraflocculus, all cerebellar cortical areas and all cerebellar nuclei receive afferents from one or more of the nuclei within the reticular formation proper, but the largest number of labelled neurons is observed in cases with injections including the intermediate-lateral part of lobulus simplex and the adjacent areas of the anterior lobe and crus I. the projection is bilateral with an ipsilateral preponderance (the cerebellar nuclei appear to receive a higher number of fibres from the contralateral side). Cells of all sizes are labelled, but labelled giant cells are found only after large cortical injections.

Chronic self-stimulation of the dentate nucleus for the relief of spasticity

It has been assumed but not yet proved that cerebellar cortical stimulation activates the Purkinje cells, with subsequent inhibition of the deep cerebellar nuclei. However, the relatively crude, widespread excitation induced by several surface electrode arrays and the parameters of stimulation currently used, may produce other effects than selective activation of only one specific cellular type which, furthermore, seems to be rarely present in these particular patients, as demonstrated by biopsy studies prior to electrode placement. The dentate nucleus was chronically implanted with a stimulating system in a patient with spasticity due to cerebral palsy. Chronic self-stimulation induced a significant improvement in motor function, with relief of spasticity and improvement in speech, posture, balance and gait. Electrophysiological studies demonstrated a decrease in the amplitude of V1 and V2 responses and in the H/M and T/M ratios, an increase in the silent period, and marked effects in the H reflex recovery curve, as well as diminished contralateral cortical somato-sensory evoked potentials. This result seems to indicate that the clinical effects of cerebellar cortical stimulation are not due to prosthetically induced inhibition of the dentate nucleus.

Some observations in treatment stimulation of epilepsy

In a group of 10 patients suffering from epilepsy therapeutic stimulation was applied by means of chronic electrodes and a technical stimulator three times in nucleus dentatus, five times in nucleus caudatus, once in both structures simultaneously. Once chronic electrodes were introduced into the amygdalo-hippocampal complex and non-specific thalanic system bilaterally. One patient was stimulated by means of a pacemaker and once by normal rhythm from the hypothalamus of the same patient using magnetic tape. The patients were subjected to stimulations once a day for a period of 1-8 days. The results obtained are being discussed with respect to Goddard's kindling phenomenon.

[Cerebellar movement disorders in monkeys. Comparison of rapidly alternating and slower target movements during cooling of the dentate nucleus (author's transl)]

The effects of short reversible cooling of the dentate nucleus in two groups of 3 and 4 cebus monkeys, with two different types of ipsilateral elbow movements, have been studied. One group was trained to turn a moving handle back and forth rapidly between two mechanical stops, while the second group was trained to move the handle between two target zones. Brief blocking of the dentate nucleus caused a delayed termination of contraction of the agonistic muscles (hypermetria) near the mechanical stop for very rapid, ballistic, alternating arm movements and, consequently, delayed initiation of the antagonistic return movement. The resulting increase of the duration of a single movement was not caused by a reduction of the peak acceleration of the movement. For the slower target movements, dentate nucleus cooling caused shortening of agonistic muscular contraction (hypometria) with corresponding, saccadic movement corrections. The frequency of the "movement tremor" lay between 3 and 5 Hz. The average velocity maxima during dentate cooling did not change. The findings indicate that different types of movements exhibit different disturbances of the movement pattern during the period of functional elimination of the same anatomical structure. The results indicate that the dentate nucleus and cerebellar hemispheres take part in preprogramming movement duration (Kornhuber) for rapid ballistic movements. In slower target movements, the dentate nucleus may be involved in sectional preprogramming of step movements.

Thalamo-cortical projections for recruiting responses and spindling-like responses in the parietal cortex

1. The thalamic neurones sending their axons to the parietal association cortex (middle suprasylvian gyrus) and receiving monosynaptic excitation from the cerebellar (interpositus or lateral) nucleus were recorded with microelectrodes extracellularly and intracellularly around the anterior ventral (VA) nucleus of the thalamus in cats. Such thalamic neurones are known to carry exclusively the impulses responsible for superficial thalamo-cortical (T-C) responses in the parietal cortex, being called superficial T-C neurones (see Sasaki et al., 1972a, b). 2. Repetitive (6--9/sec) stimulation of the centrum medianum-parafascicular complex (CM) or the intralaminar nuclei (IL) of the thalamus elicited grouped spike discharges of the neurone in synchronization with the recruiting responses in the parietal cortex. The grouped discharges usually preceded the respective cortical responses by several milliseconds. Numbers of the spikes in the grouped discharges increased and decreased as the recruiting responses waxed and waned on the repetitive stimulation. 3. The superficial T-C neurones also showed similar grouped discharges in synchronization with spindling-like, surface-negative cortical responses which occurred spontaneously or were evoked by single thalamic stimulation. 4. It was concluded that the superficial T-C neurons can convey impulses for recruiting responses and spindling-like responses from the thalamus directly to the cerebral cortex. They are supposed to constitute the final T-C pathway of the neuronal circuits of the recruiting system, i.e., non-specific T-C projection system.

Distribution of microglial clusters in the brain after head injury

The brains of 12 cases of head injury have been submitted to gross pathological study and microscopic examination by the Weil-Davenport method, with special reference to the corpus callosum, internal capsules, and brain-stem in each case. Microglial clusters were observed in 11 out of 12 cases, the most common sites for these being the corpus callosum ipsilateral to the external applied force and the internal capsule and brain-stem contralateral to this applied force. This pattern of distribution of lesions remained constant in all cases. The nature, aetiology, and distribution of these lesions is discussed and it is concluded that such lesions arise from the formation of definite patterns of shearing forces which snap axons. These forces arise from the rotational movements set up within the skull resulting from the relative delay of movement of the brain with respect to the skull and dura mater.

The cerebellum as a computer: patterns in space and time

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The effect of the removal of the nucleus dentatus on the parkinsonian syndrome

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The effects upon vestibular function in the cat of unilateral destruction of the nucleus fastigii

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