[Electrophysiologic study of the serotoninergic neuron C1 in the pteropod mollusk Clione].

Functional characteristics of the cerebral serotoninergic neuron (C1) have been studied in the pteropod mollusc Clione limacina. The C1 neuron axon projected to the buccal ganglia and axon collaterals terminated in buccal nerves. Stimulation of the C1 neuron activated the feeding rhythm generator in the buccal ganglia.

[The neuronal mechanisms of the escape reaction to stimulation of the statocyst receptors in the freshwater snail].

Tilts of the freshwater snail Planorbarius corneus, resulting in statocyst receptor stimulation, induced the defensive reaction including pulling down of the shell, shortening of the foot, inhibition of locomotion and feeding. The preparation of the central nervous system has demonstrated that many inter- and motoneurons from different ganglia were involved in this reaction. Usually the reaction was of "all or none" manner.

[The neuronal mechanisms of the defensive reaction to stimulation of the cutaneous nerve in the freshwater snail].

The whole body withdrawal reaction of freshwater snail Planorbarius corneus consists of two phases. In the first phase the shell is rapidly moved down to cover the head, in the second one the body is slowly retracted into the shell. The columellar muscle is involved in this behaviour.

[Neural regulation of heart function in the Pteropod mollusc Clione limacina].

The heart of the pteropodial mollusc Clione limacina is innervated by the median nerve arising from the left abdominal ganglion. Five neurons sending axons to the heart have been identified in the Clione central nervous system with retrograde cobalt or Lucifer yellow staining. Neuron H1 located in the left pedal ganglion evoked heart excitation.

[Neuronal mechanisms of the generation of the feeding rhythm in the buccal ganglia of the pteropod mollusk].

Two antagonistic groups of neurons, active in protractor and retractor phases of the feeding cycle, were found in the buccal ganglia of the pteropod mollusc Clione limacina. Neurons within each group are electrically coupled, while the groups inhibit one another. Each group is able to perform independent rhythmic activity.

[Growth of neurites and formation of connections in cultures of pteropodial mollusc neurons].

Dissociated neurons from the brain of pteropodial mollusc were cultivated in a 25% Leibovitz medium containing 2% of calf serum. Neurite outgrowth was observed in 1-30% of the neurons. It was maximum during the first 3 days.

[Effect of the locomotor system of the pedal ganglia of the pteropodial mollusk on anatomically isolated neurons].

The isolated pedal ganglia of the pteropodial mollusc Clione limacina generate the locomotor activity. In 30% of the pedal ganglion preparations, the locomotor rhythm was not regular, i. e.

[Regeneration of neurons of the pedal ganglion of the pteropodal mollusk Clione limacina].

In pedal ganglia of mollusc Clione limacina the growth of axons was studied in motoneurons and interneurons after transections of the wing nerve or of the pedal comissure. Neurons were stained by Lucifer Yellow. In motoneurons, neurites grown both from the transected end of the axon and from the neuron soma spread to all nerve trunks of ipsi- and contralateral ganglia.

[Proportion of short propriospinal fibers in the lumbar division of the spinal cord of the cat].

Stimulating and recording electrodes were located at various distances from each other either in the lateral or in the ventral funiculus of the lumbar spinal cord of decerebrated curarized cats. The recorded response considerably decreased at the distance of 10-15 mm, suggesting that most propriospinal fibres have a length not exceeding the length of one or two spinal segments.

[Activity of propriospinal neurons of segments C3 and C4 during "fictive locomotion" in the cat].

The activity of C3-C4 propriospinal neurons was recorded during "fictitious locomotion" of forelimbs in immobilized decerebrated cats with the spinal cord transected at the lower thoracal level. The neurons were identified by the antidromic responses to stimulation of the lateral funiculus in the C6 segment. Most of the neurons (70%) were antidromically activated also from the lateral reticular nucleus.

[Activity of isolated interneurons of the pedal ganglia of the pteropodal mollusk].

Interneurons from pedal ganglia of marine mollusc Clione limacina continued their rhythmical discharges for many hours after isolation. A discharge frequency increased with depolarization of neurons and decreased with hyperpolarization. It is concluded that the endogenous activity of interneurons underlies generation of the locomotor pattern in mollusc pedal ganglia.

[Generation of locomotor rhythms in Limacina helicina].

Two groups of neurons (motoneurons and putative interneurons), exhibiting periodic activity with the locomotory rhythm, were recorded in the pedal ganglia of the isolated nervous system of the mollusc Limacina helicina. Motoneurons periodically generated spike bursts, while interneurons generated only one prolonged (100-400 ms) action potential per cycle. Rhythmic generation persisted after blocking the spike discharges of motoneurons by means of tetrodotoxin.

[Neurons of the pedal ganglia of a pteropod mollusk regulating locomotor generator function].

Neurons whose excitation affected the locomotory rhythm were recorded in the isolated pedal ganglia of the marine mollusc Clione limacina. Some of these neurons generated "plateau" potentials, i.e.

[Interneuron activity of the pedal ganglia of pteropod mollusks during generation of locomotor rhythms].

Activity of interneurons from isolated pedal ganglia of marine mollusc Clione limacina was recorded during generation of the locomotor rhythm. Two groups of reciprocally active interneurons were found. These neurons generate one prolonged action potential per locomotory cycle.

[Motor neuron activity of the pedal ganglia of pteropod mollusks during generation of locomotor rhythms].

Activity of motoneurons from pedal ganglia of marine mollusc Clione limacina was recorded during generation of the locomotor rhythm. Motoneuron groups controlling antagonistic wing muscles are active alternatively, excitation of one group being accompanied by inhibition of the other group. Many synergetic motoneurons are electrically coupled.

[Effect of serotonin and theophylline on generation of rhythmic activity in the buccal ganglia of gastropod mollusks].

Effect of serotonin on generation of the feeding rhythm in buccal ganglia was studied in 8 species from 3 subclasses of gastropod molluscs. Serotonin (10(-5) mol/l) initiated or increased the rhythmical activity in the buccal ganglia. The effect of serotonin was potentiated with theophylline (phosphodiesterase inhibitor).

[Activity of propriospinal neurons of the ventral horn of the superior lumbar segments during fictive scratch reflexes].

Activity of propriospinal neurons from the ventral horn of segments L4 and L3 was recorded during fictitious scratch reflex in decerebrated cats. Neurons were identified by their antidromic response to stimulation of the ventral surface of the L7 segment. Most neurons were not active during scratching.

[Locomotion of Barents Sea ophiuroids].

Locomotion of 5 species of Ophiuroids from the Barents Sea has been described--Ophiura albida, O. robusta, O. sarsi, Ophiacantha bidentata, Ophiopholis aculeata.

[Vestibular reactions of neurons of the cerebellar nucleus dentatus and nucleus interpositus in cats].

The response of interpositus and dentate neurons to the sinusoidal tilts in the frontal plane were studied in thalamic cats. In interpositus nucleus 65% neurons responded to the tilts. Their responses were not uniform: some neurons showed an increased activity during the contralateral tilt, others--during ipsilateral tilt, and some neurons--during tilts in both directions.

[Activity of cerebellar fastigial nucleus neurons during the fictive scratching reflex in cats].

The activity of neurons in the rostral part of the fastigial nucleus was recorded during fictious scratch reflex (FSR) in immobilized cats. During FSR the discharge frequency of many fastigial neurons was rhythmically modulated in relation to the scratch cycle: most of them fired in bursts at the end of the flexor phase or at the extensor phase of the cycle. The firing pattern of fastigial neurons was similar during both ipsilateral and contralateral FSR.

[Variations in the membrane potentials of motor neurons during the generation of scratching].

The activity of motoneurons of the ankle flexor and extensor muscles was recorded intracellularly during fictitious scratching in decerebrate curarized cats. Before the beginning of rhythmical oscillation a large depolarization and tonic discharge were observed in flexor motoneurons, while the membrane potential of extensor ones did not change. When the rhythmical generation began, a short periodic hyperpolarization and corresponding pause in the discharge lasting for the extensor phase of the cycle appeared in flexor motoneurons.