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Biomedical subjects

L B Popova

Publications and source records attributed to L B Popova.

31 records · Page 2Linked to original sources
PubMed1985

Effects of stimulation of midline inhibitory area within the pontine tegmentum on scratch reflex.

Effects of stimulation of the midline inhibitory area of the dorsal tegmental field (DTF) in the pons on the fictive scratch reflex were studied in decerebrate immobilized cats. The fictive scratch reflex was evoked by tactile stimulation of the pinna. DTF stimulation suppressed both the scratch-related rhythmical activities of the nerves (ENGs) supplying m. lateralis gastrocnemius and m. tibialis anterior, and of the interneurons at the 'leading' area of the spinal cord (L5 segment) where the scratch rhythm generator is presumably located.

Animals↗
PubMed1985

[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. The discharge frequency of most neurons was rhythmically modulated in correlation with the motoneuron activity during "fictitious locomotion", i.e. in the absence of any rhythmical signals from the limb receptors. The cooling of the rostral area of the cervical enlargement abolished both the generation of the locomotor rhythm and the rhythmical activity of the propriospinal neurons. Therefore intraspinal mechanisms controlling the forelimb activity are the main source for rhythmical modulation of the C3-C4 propriospinal neurons.

Animals↗
PubMed1985

[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.

Animals↗
PubMed1984

Activity of cerebellar Purkinje cells during fictitious scratch reflex in the cat.

The activity of Purkinje cells (PCs) was recorded in the anterior lobe (the vermis and pars intermedia) and in the paramedian lobule of the cerebellum during the fictitious scratch reflex in thalamic cats immobilized with Flaxedil. In the anterior lobe, the activity of many PCs was rhythmically modulated in relation to the scratch cycle: they generated bursts of impulses separated by periods of silence. Different PCs were active in different phases of the scratch cycle. In many cases the discharge modulation was irregular: the burst duration and the discharge rate in the burst varied considerably in subsequent cycles. The rhythmical activity of PCs was determined by modulation of the frequency of 'simple spikes' reflecting the mossy fiber input. Generation of 'complex spikes' reflecting the climbing fiber input in most PCs was not related with the scratch rhythm. In the paramedian lobule, rhythmical modulation of PCs was practically absent. Rhythmical modulation of PCs in immobilized cats is determined by signals coming from the central spinal mechanism of scratching via the ventral spinocerebellar tract (VSCT) and the spinoreticulocerebellar pathway (SRCP). Results of separate transections of these pathways demonstrated that the VSCT plays the crucial role in modulating the PCs.

Afferent Pathways↗
PubMed1984

Origin of signals conveyed by the ventral spino-cerebellar tract and spino-reticulo-cerebellar pathway.

The "fictitious" scratch reflex was evoked in decerebrate curarized cats by pinna stimulation. Activity of neurons of the ventral spino-cerebellar tract ( VSCT ) from the L4 and L5 segments of the spinal cord as well as of neurons of the spino-reticulo-cerebellar pathway ( SRCP ) from the lateral reticular nucleus of the medulla oblongata was recorded. Cooling and destruction of different parts of the lumbo-sacral enlargement of the spinal cord were performed. Cooling of the L5 or L6 segment abolished the rhythmic activity in the greater part of the spinal hindlimb centre but did not affect the generation of rhythmic oscillations in the remaining (rostral) segments of the lumbo-sacral enlargement. Under these conditions, neither the rhythmic activity of VSCT neurons located rostral to the thermode nor that of SRCP neurons changed. A normal rhythmic activity of SRCP neurons also persisted after destruction of grey matter in the L3 and L4 segments. It can be concluded that activity of these neurons is independent of whichever part of the enlargement generates rhythmic oscillations. From these observations a hypothesis is advanced that the main content of signals conveyed by the VSCT and SRCP to the cerebellum is the information regarding activity of the generator of rhythmic oscillations that is located in the L3-L5 spinal segments.

Animals↗
PubMed1982

[Analysis of late components of evoked potentials arising in the paramedian lobule of the cerebellum in response to stimulation of nerves and the cerebral cortex].

The field potentials in response to stimulation of the cerebral sensorimotor cortex and of the limb nerves were recorded in the granular layer of the cerebellar paramedian lobule in nonanesthetized cats. The field potentials contained long-latency components, i.e. slow negative waves generated by granule cells. The long-latency component to nerve stimulation was recorded both inside and outside the projection area of the given limb, while the cerebral stimulation with a low intensity (1.8-2.5 thresholds) evoked this component in the given projection area only. The long latency component to cerebral stimulation followed higher rates and was less sensitive to the action of the barbital anaesthesia than the component following the nerve stimulation. Simultaneous cerebral and nerve stimulation evoked the long latency component equal to the sum of the separate components. It is suggested that slow conduction spinal and cerebral inputs form separate mossy fibres - granule cell pathways.

Animals↗
PubMed1981

[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. This finding suggests that this group of neurons does not participate in the control of motoneurons during the activity of intrinsic spinal networks but rather participates in the transmission of supraspinal commands to motoneurons.

Animals↗
PubMed1979

[Possibility of using an analgesic (fentanyl) for electrophysiologic studies of the cerebellar cortex].

The effect of the central analgetic, fentanyl, on evoked potentials and Purkinje cells discharges in the cerbellar cortex to stimulation either the cerebral cortex or somatic nerves were studied in nonanaesthetized cats. It was found that the analgetic dose fentanyl (10-30 microgram/kg) did not affect the evoked potentials. The fentanyl dose of 30 microgram/kg suppressed the resting discharges and responses of Purkinje cells while the dose of 10 microgram/kg facilitated them. However these effects were substantially weaker as compared with those of nembutal. Therefore fentanyl can be used for analgesia during electrophysiological study of the cerebellar cortex in nonanaesthetized cats.

Animals↗
PubMedDate not supplied

Staining of central neurons of the pteropod mollusk Clione limacina with fluorescein-labeled alpha-bungarotoxin.

Fluorescein-labeled alpha-bungarotoxin (alphaBT/FITC) was used to identify neurons bearing acetylcholine receptors in the central nervous system of the pteropod mollusk Clione limacina. AlphaBT/FITC stained two small symmetrical neurons on the dorsal surface of the cerebral ganglia. The stain was highly specific and was completely blocked by preincubation with a very low concentration of unlabeled alpha-bungarotoxin (1 nM). Nicotinic receptor agonists and antagonists effectively blocked staining with alphaBT/FITC, while muscarinic agonists and antagonists had no effect. This provides evidence that alphaBT/FITC genuinely binds to acetylcholine receptors. The possible role of the alphaBT/FITC-stained cells in the hunting behavioral complex of Clione is discussed.

Animals↗
PubMedDate not supplied

[Occurrence and parasite fauna of Dressena bugensis in the Rybinsk reservoir].

The zebra mussel Dreissena bugensis (Andrusov), a representative of mollusc fauna in the Dnieper-Bug estuary, have been found for the first time in the Rybinsk reservoir (the Volga reach, Shumorovka River). In pericardial and mantle cavities and inner organs of molluscs the following parsites have been found: Aspidogaster limacoides, Caspiobdella fadejevi, Helobdella stagnalis, eggs of the water mites of the genus Unionicola, and representatives of nonspecific saprotrophic fungi of the genus Acremonium. It is shown that composition of parasites and free-living organisms in D. bugensis is similar to that in D. polymorpha.

Animals↗
PubMedDate not supplied

[The staining of the central neurons in the pteropod mollusk Clione limacina with fluorescein-labelled alpha-bungarotoxin].

FITC-labelled alpha-bungarotoxin (alpha BT[FITC]) was used to identify acetylcholine (ACh)-sensitive neurons in the central nervous system of pteropod mollusc Clione limacina. Two small symmetrical neurons were stained with alpha BT[FITC] on the dorsal surface of the cerebral ganglia. The staining was highly specific as it was completely blocked by preincubation in alpha-bungarotoxin [alpha BT] at very low concentration (10(-9) M). Nicotinic agonists and antagonists efficiently prevented alpha BT[FITC] staining while muscarinic agonists and antagonists had no effect. These findings confirm the suggestion that alpha BT[FITC] binds to nicotinic ACh receptors. The possible role is discussed of alpha BT[FITC]-stained cells in the complex of hunting behavior of Clione.

Acetylcholine↗