[The nature of cardiogenic sympatho-sympathetic reflexes in focal injuries of the heart]. / O prirode kardiogennykh simpatosimpaticheskikh refleksov pri ochagovykh povrezhceniiakh serdtsa.

The nature and dynamics of cardiogenic sympatho-sympathetic reflexes in response to intracoronary administration of veratrin, bradykinin, and to local immune heart injury were studied in anesthetized dogs. The sympatho-sympathetic reflex was shown to occur both in vagotomized and intact animals, though in the latter case the reflex was transformed due to descending influences from the bulbar center. The reflex was the least in case of veratrin administration and it was most obvious in bradykinin application or upon focal immune heart injury which indicates a greater sensitivity of sympathetic receptors to chemical agents.

[Mechanisms of the development of cardiogenic vagosympathetic reflexes]. / O mekhanizmakh razvitiia kardiogennykh vagosimpaticheskikh refleksov.

Mechanisms of development of cardiogenic vagosympathetic depressor reflexes during adrenergic heart stimulation and local immune and ischemic damages of the left ventricle were studied in anesthetized dogs and cats by recording afferent and efferent impulsation from cardiac nerves as well as cardiodynamic indices. Impulse activity in cardiac nerves showed reciprocal changes: an increase in frequency of afferent impulsation in vagal nerves and inhibition of efferent impulsation in sympathetic nerves. The data obtained suggest that stimulation of heart mechanoreceptors due to the increase of myocardial contractility and asynergy of the left ventricle, is a triggering mechanism for reflex inhibition of sympathetic impulsation and depressor reflex.

[Cortical control of afferent flow in the lateral geniculate body in the cat]. / Korkoyi kontrol' afferentnogo potoka v naruzhnom kolenchatom tele koshki.

In experiments carried out on cats immobilized with d-tubocurarine unit responses within the dorsolateral geniculate nucleus were analyzed following visual cortex (testing) and optic chiasm (conditioning) stimulation. Two types of responses were found indicating the existence of principal and inhibitory cells in the nucleus. Optic chiasm stimulation was found to produce an inhibitory corticofugal effect on the responses of principal cells. A conclusion is made that these effects are mediated by inhibitory cells.

[Correlation between conduction velocities in fibers of the optic nerve and optic radiation in cats]. / Korreliatsiia skorostei provedeniia vozbuzhdeniia v voloknakh zritel'nogo nerva i zritel'noi radiatsii koshki.

The responses of dorsal lateral geniculate body units to striate cortex and optic chiasm stimulation were examined in cats immobilized with d-tubocurarine. A high correlation between antidromic responses to striate cortex and orthodromic responses to optic chiasm stimulation was found (r=0.895; P=0.01). 9% of neurons responded antidromically to optic chiasm stimulation indicating the existence of centrifugal fibres in the optic nerve. The functional significance of time dispersion of the afferent volley in visual system is discussed.

Centrifugal and centripetal connections of the cat visual cortex.

In experiments on curarized cats unit responses in the dorsal lateral geniculate body to stimulation of various zones in area 17 of the visual cortex were analyzed. Of all cells tested 69% were found to respond antidromically and 8% orthodromically; in 7.6% of cells IPSPs occurred either after an initial antidromic spike or without it. The velocities of conduction of excitation along the corticopetal fibers of the optic radiation varied from 28 to 4.3 m/sec, but the three commonest groups of fibers had conduction velocities of 28-19, 14-12, and 10-9.5 m/sec. A difference between latent periods of antidromic responses of the same neurons was found to stimulation of different zones of the visual cortex; this indicates that axons of geniculo-cortical fibers split into several branches which form contacts with several neurons in area 17 of the visual cortex. The degree and possible mechanisms of cortical influences on neurons of the lateral geniculate body are discussed.

[Post-synaptic responses of cat visual cortex neurons to stimulation of the lateral geniculate body]. / Postsinapticheskie reaktsii neironov zritel'noi kory koshki na razdrazhenie naruzhnogo kolenchatogo tela.

Intracellular responses of 50 neurons in the striate cortex to lateral geniculate body stimulation were studied in cats immobilized with d-tubocurarine. Activation without subsequent inhibition was determined in 22 per cent of the cells. Initial activation was followed by inhibition in 32 per cent of the cells and primary inhibition was found in 46 per cent of the cells. The difference between the shortest latencies of IPSP and EPSP was 0.9 ms. A conclusion is made that in the striate cortex there exists a mechanism of afferent inhibition. The neurons responding with primary activation may play the role of inhibitory cells in such inhibition.

[Centrifugal and centripetal connections of the cat visual cortex]. / Tsentrobezhnye i tsentrostremitel'nye sviazi zritel'noi kory koshki]

The responses of the dorsal LGB units to the striate cortex stimulation were examined in cats paralized with d-tubocurarine. Most cells studied were activated antidromically but only 8% demonstrated orthodromic responses. Some units studied intracellularly exhibited antidromic spikes followed by IPSPs, sometimes only IPSP was observed. The conduction velocities of the corticipetal fibres ranged between 28 and 4.3 m/s; three groups of fibres with conduction velocities 28-19, 14-12, 10-9.5 m/s could be separated in them in most cases. Some of the antidromically responding units had different response latencies to different striate areas stumulation, indicating that these units project to the striate cortex by means of a branching axon. Possible mechanisms of cortical influence on the LGB neurons are discussed.

[Conduction of excitation in the cat vixual system]. / O provedenii vozbuzhdeniia v zritel'noi sistem koshki

The responses of striate cortex units to the lateral geniculate body and optic tract stimulations were recorded extra- and intracellularly in experiments on cats immobilized with d-tubocurarine. 92% of responded cells were activated orthodromically with a latency ranging between 2 and 12.5 ms. Most of these responses may be divided into three groups--2-2.5, 3-3.5, 4-4.5 ms. The latency of each group coincided with the latency of three different parts of the evoked potentials positive components. 8% of the responding cells were activated antidromically. The difference of the response latency to the stimulation of both structures in 55.8% of cells ranged from 0.5 to 1 ms. The existence of three main groups of optic radiation fibres with conduction velocities of 28.5-16.6, 11.7-8.9, 7.4-6 m/s is postulated. A conclusion is made that peculiarities of the afferent volley formed in retino-geniculate paths are not significantly changed after its processing in the lateral geniculate body.