[Ukhtomskii--the teacher (based on memoirs and letters)]. / Ukhtomskii--uchitel' (po vospominaniiam i pis'mam).

This article has been written by pupil of A.A. Ukhtomsky, well-known professor of Moscow State University M.V. Kirzon. The article discovers the personal qualities of outstanding biologist A.A. Ukhtomsky, who has founded one of the famed physiological scientific schools in the Soviet Union.

[Effect of novocaine block of limbic system formations of the brain, hypothalamus and reticular formation on evoked potentials in the ventrobasal thalamic nucleus of the rat]. / Vliianie blokirovaniia novokainom nekotorykh obrazovanii limbicheskoi sistemy mozga, gipotalamusa i retikuliarnoi formatsii na vyzvannye potentsialy v ventrobazal'nom komplekse talamusa krysy.

The effect of novocain on evoked potentials (EP) recorded from the ventrobasal complex (VBC) of rats thalamus has been studied during a single pulse stimulation of the contralateral hind paw immobilized with curare. It has been established that significant sinchronized decrease of amplitudes of all the three early components of EP has been observed during the novocain administration in the reticular thalamic nucleus, lateral amygdaloid area and septum. During the blocking of the anterior and posterior hypothalamus the amplitude of the second negative component of EP in VBC decreases, while during the blocking of the dorsal hypothalamus an increase of the amplitudes of all the three early components of EP is mainly observed.

Depression of evoked potentials in rat thalamic ventro-basal complex and somatosensory cortex after reticular stimulation.

Experiments on unanesthetized rats immobilized with D-tubocurarine showed that electrical stimulation (100/sec) of the central gray matter and the mesencephalic and medullary reticular formation considerably depressed potentials in the somatic thalamic relay nucleus and somatosensory cortex evoked by stimulation of the forelimb or medial lemniscus. The mean threshold values of the current used for electrical stimulation of these structures did not differ significantly and were 70 (20--100), 100(20--120), and 120 (50--200) muA, respectively. On comparison of the amplitude-temporal characteristics of inhibition of evoked potentials during electrical stimulation of the above-mentioned structures by a current of twice the threshold strength, no significant differences were found. Immediately after the end of electrical stimulation the amplitude of the cortical evolved potential and the post-synpatic components of the thalamic evoked potential was 50--60% (P less than 0.01) below the control values. The duration of this depression varied from 0.5 to 1 sec. An increase in the intensity of electrical stimulation of brain-stem structures to between three and five times the threshold led to depression of the presynaptic component of the thalamic evoked potential also. Depression of the evoked potential as described above was found with various ratios between the intensities of conditioning and testing stimuli.

[Responses of the neuromuscular synapses of chronically desympathized frog muscles to tetanic nerve stimulation]. / Reaktsiia nervno-myshechnogo sinapsa khronicheski desimpatizirovannoi myshtsy liagushki na tetanicheskoe razdrazhenie nerva

7--14 days after unilateral section of the abdominal sympathetic trunk, the quantum content of the end plate potential (e.p.p.) in the m. sartorius of the frog decreased. The facilitation and fluctuations of the e.p.p. amplitude during train of stimuli (20, 50, 100/sec) became more obvious. Noradrenaline (5-10(-6) g/ml) increased the amplitude of a single e.p.p. and the facilitation during repetitive stimulation. The effect of noradrenaline in sympathectomized muscles was more obvious than in the control muscles. After the noradrenaline administration, the fourfold increase of calcium concentration did not change the amplitude of e.p.p.s or the time course of the facilitation. The mechanism of depolarization--secretion coupling in the nerve terminal seems to be impaired by the sympathectomy.

[Reticular inhibition of evoked potentials of the ventro-basal thalamus and somatosensory cortex of the rat brain]. / Retikuliarnoe ugnetenie vyzvannykh potentsialov ventro-bazal'nogo talamusa i somato-sensornoi kory golovnogo mozga krysy

In rats immobilized with d-tubocurarine conditioning electrical stimulation (100/s, 300 ms) of the central grey matter, reticular formation of the midbrain and medulla depressed focal potentials in thalamic ventro-basal complex and somatosensory cortex evoked by electrical stimulation of the forelimb or medial meniscus. The average threshold current for conditioning stimulation of these structures was 70, 100 and 120 muA. A comparison of intensity and duration of evoked potentials depression (for two-fold threshold stimulation of the brain stem) is failed to detect any difference between the stimulated structures: immediately after conditioning stimulation the amplitude of the cortical evoked potentials and post-synaptic components of the evoked potentials in the ventro-basal complex were 50-60% less than control amplitude (p less than 0.01) the depression persisting for 0.5-1 s. The presynaptic component of the thalamic evoked potentials was depressed only after three five-fold threshold conditioning stimulation. The brain stem stimulation did not cause any facilitatory effect on focal potentials evoked by maximal and submaximal stimulation of the forelimb or medial lemniscus.