Pyramidal influences in establishment of new motor coordinations in dogs

Ablation of the motor cortex or section of the pyramidal tracts in dogs were studied for their effects on the performance of an alimentary instrumental reaction. The animal was required to keep its foreleg raised during feeding in order to gain access to food. The operated animals were capable of raising the leg in response to a signal and of holding it, but when snatching the food they immediately lower it. These dogs can, however, accomplish such a conditioned reflex if they do not have to lower the head during feeding. There may exist inborn reflexes from the cervical muscles or the vestibular apparatus ensuring the support on the forelegs when the head is lowered for feeding. When a new coordination including feeding with the leg raised, is elaborated, these inborn coordinations are inhibited. Evidently, inhibition of such inborn coordinations is effected through the pyramidal tract. The pyramidotomized animal is incapable of inhibiting the reation of lowering its leg when feeding with head down and cannot therefore keep its leg raised when feeding. However, there is no need of inhibiting inborn coordiantions when feeding with the head raised. For this reason pyramidotomized dogs are capable of keeping the leg raised in the latter condition.     

Pharmacological correction of experimental alcohol embryopathy

Laboratory of Experimental Pathology and Therapy of Higher Nervous Activity and Laboratory of Morphology of the Central Nervous System, Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. S. Rusinov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 106, No. 8, pp. 178–180, August, 1988.     

Modulation of the baroreceptor reflex by central administration of angiotensin

Pulsatile pressures ranging from 50 to 200 mm Hg were applied to the isolaetd carotid sinuses of dogs. Vascular resistance changes were monitored in isolated gracilis muscle and hindpaw perfused at constant flow. In muscle, reducing the carotid sinus pressure caused increased reflex vasoconstriction durign intravertebral (i.vert.) angiotensin infusion of 10 ng/kg/min. Reflex vsaodilator response to increased carotid sinus pressure were not altered. Reflex responses to high or low carotid sinus pressures during a lower i.vert. angiotensin infusion or i.v. infusion of either dose were also unaffected. In general, baroreceptor initiated reflex vascular activity in the hindpaw was not influenced by i.vert. or i.v. angiotensin. These data demonstrate that through a central mechanism angiotensin causes a dose-dependent shift in the relationship between low carotid sinus pressures and adrenergic discharge to muscle beds.     

Modification by Baroreceptor Feedback of Circulatory Responses to Noxious Stimuli During Anaesthesia in Cats

In eight cats anaesthetized with chloralose, the carotid sinus on one side was either exposed to systemic arterial pressure or perfused with a pump in order to control sinus pressure. Baroreceptor influences from the contralateral carotid sinus and from the aortic arch were interrupted by denervation. Arrangements were made for intermittent electric stimulation of pain fibres in somatic and visceral nerves with stimulation parameters chosen to elicit reproducible increases in arterial blood pressure and in skeletal muscle vascular resistance. The elicited increases in arterial pressure and muscle vascular resistance were both about 40% smaller when the carotid sinus was exposed to systemic arterial pressure in comparison with the experimental condition of a constant carotid sinus pressure. I.v. metoprolol (0.1-0.3 mg kg-1) reduced base-line arterial pressure, but did not attenuate the arterial blood pressure increase in response to pain stimulation. The baroreceptor modulation of the haemodynamic response to the pain stimulation was not affected by metoprolol.     

Electrophysiological studies on interpositus neurones in the normal and Lurcher mutant mouse

Summary The response characteristics of interpositus neurones (IP) to sciatic nerve stimulation were studied in normal and Lurcher mutant mice under pentobarbitone anaesthesia. The response of IP neurones in the normal mouse was a short latency bimodal excitation (E1-I1-E2) followed by a depression of the firing rate (I2) and ending with a longer latency excitation (E3) which was completed within 225 msec. The response of the majority of IP neurones in the Lurcher mouse was a short latency unimodal excitation (LE1) which corresponded in time to the E1-I1-E2 phase in the normal. This was followed by a pause in the excitation. The response ended with a longer latency excitation (LE2) corresponding in time to the E3 phase in the normal mouse but which persisted for a considerably greater period of time. The response of IP neurones in normal and Lurcher mice appear to be similar to those observed in the normal and experimentally cerebellar decorticate cat, respectively.     

Mediator mechanisms of cathinone effects on animal behaviour

The effect of cathinone on the visual differentiation of cats was investigated by the method of defense conditioned reflexes. It was found that cathinone decreases the differentiation of both the short-term and prolonged visual stimuli. These effects of cathinone increase when the serotoninergic system is activated and decrease under dopaminergic system activation.     

Pharmacological studies on facial motoneurones in the rat

Experiments were performed on 39 male albino rats anaesthetized with pentobarbitone sodium and paralyzed with gallamine triethiodide. Facial motoneurones consistently showed a progressive alteration of spike shape and decrease in spike firing frequency during the continuous microelectrophoretic application of the excitant amino acids D,L-homocysteate, L-glutamate, L-aspartate, and kainate, but infrequently during that of N-methyl-D-asparate. The relative potencies of these excitants on facial motoneurones are reported. The potential usefulness of N-methyl-D-aspartate to produce amino acid-evoked motoneurone action potentials is discussed.The microelectrophoretically-applied depressant amino acid antagonist strychnine selectively and reversibly blocked the depressant effects of glycine on facial motoneurones. The depression of amino acid-induced firing of facial motoneurones by stimuli to the lingual or glossopharyngeal nerves were reversibly antagonized by microelectrophoretically applied strychnine but not by bicuculine.     

Follow-up study of children with cerebral coordination disturbance (CCD, Vojta)

713 children (from newborn to 12-month-old) with delayed motor development were carefully examined and classified into normal, very light cerebral coordination disturbance (CCD, Vojta), light CCD, moderate CCD, severe CCD, suspected cerebral palsy (CP) and other diseases at their first visit, and were followed up carefully. Finally, 89.0% of very light CCD, 71.4% of light CCD, 56.0% of moderate CCD and 30.0% of severe CCD developed into normal. 59.5% of moderate CCD and 45.5% of severe CCD among children who were given Vojta's physiotherapy developed into normal. The classification of cases with delayed motor development into very light, light, moderate and severe CCD based on the extent of abnormality in their postural reflexes is useful and well correlated with their prognosis. Treatment by Vojta's method seems to be efficient and helpful for young children with delayed motor development.     

Activation by diphenylthiohydantoin of inhibitory influences on spinal motor activity

The effect of diphenylthiohydantoin (DPTH) on spinal reflex activity (mono- and polysynaptic mass reflexes) in cervical and lumbar segments was studied in precollicularly decerebrate cats. DPTH (20 mg/kg) depressed the reflex activity in preparations with an intact spinal cord. It increased the reflex activity after removal of the anterior lobe of the cerebellum and after low spinalization; in the latter preparation, diphenylhydantoin produced an effect similar to that of DPTH but a longer duration. Reciprocal inhibition as well as ascending and descending intraspinal inhibition was increased by DPTH. From the results it is concluded that DPTH, apart from activating spinal reflexes, stimulates inhibition. Stimulation of inhibition may also account for the anticonvulsive action of the drug.