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S Trojan

Publications and source records attributed to S Trojan.

At least 145 records · Page 8Linked to original sources
PubMed1983

Chronic changes in the receptive field of the pyramidal cells of the rat hippocampus after intermittent postnatal hypoxia.

The structure of pyramidal cells in the CA1 hippocampal region, impregnated by the Golgi-Cox method, was studied in adult rats which had been repeatedly exposed to aerogenic hypoxia from birth till the 17th day of life. The length of basal dendrite branches was the same in the experimental and control animals. The branches of apical dendrites were longer after hypoxia [p less than 0.01] due to the higher number of proximal lateral dendrites [p less than 0.01]. On the other hand, a smaller number of branches was found in the distal parts of apical dendrites. The density of spines upon selected standard segments of the branches was decreased [p less than 0.01]. The spines of these animals had a shorter stem, and were more robust and club shaped. The structural differences in the hippocampus, caused by the hypoxia in the first weeks of life, were resistuted during the subsequent development only partially. Changes in the extent and arrangement of the neuronal receptive field, similarly as the transmission properties of dendritic spines, present in adult rats, may be the cause of some functional changes in hippocampal neuronal circuits.

Animals↗
PubMed1983

Influence of certain stimulation parameters on the character of the cortical self-sustained after-discharge.

The ECoG pattern of self-sustained after-discharges (SSADs) evoked by rhythmic electrical stimulation of the cerebral cortex is far from uniform. In acute experiments on male rats the authors studied the significance of the frequency, intensity and length of stimulation for the character of the resultant SSAD. In the first group (11 rats), a stimulation frequency of 8 Hz was used; the stimulation series, which lasted 10 and 20 s, always led to the formation of a SSAD composed of spike-and-wave rhythm right from the outset. Shortening the time of stimulation markedly reduced its effectiveness. In the second group (10 animals), stimulation with 50 Hz frequency often evoked a complex SSAD starting with desynchronization, which was followed by fast spike activity of increasing amplitude and only later by spike-and-wave rhythm or by polyspike-and-wave rhythm. Towards the end, serrated waves--i.e. graphoelements typical of SSADs evoked by electrical stimulation of limbic structures--often appeared in the SSAD. A higher stimulation intensity increased the incidence of this complex SSAD. In this group a minimum duration of stimulation was also essential (series of less than 2 s were not reliably effective). When this second type of SSAD ended, depression of ECoG activity was followed in 27% of the cases by a spontaneous recurrent seizure (RS). The ECoG character of these RS can be very variable. The two types of seizures evoked by slow and fast stimulation differ from each other not only in respect of their ECoG pattern (where the difference is probably due to more pronounced propagation to subcortical structures after faster stimulation), but also as regards the presumed mechanism of their onset.

Animals↗
PubMed1982

Ontogenetic development of rhythmic thalamo-cortical phenomena in the rat.

Three rhythmic cortical phenomena (rhythmic after-discharges, incremental responses and self-sustained after-discharges formed by spike-and-wave rhythm) were elicited by electrical stimulation of thalamic nuclei during ontogenesis in rats. All three phenomena could be recorded for the first time at the age of 12 days and they matured until the 18th postnatal day. Possible explanation for the delayed development of these rhythmic thalamo-cortical phenomena in comparison with single thalamo-cortical responses are discussed.

Aging↗
PubMed1982

Changes in the structure of the rat hippocampus after prolonged postnatal hypoxia.

The authors compare the structure of the pyramidal neurones in the CA1 region of the hippocampus in rats repeatedly exposed to aerogenic hypoxia from birth to the age of 17 days and in control animals. In preparations from 18-day-old animals impregnated by the Colgi-Cox method the length of the dendrites and the density of the spines were quantitatively evaluated together with the shape of the spines at various segments of the dendritic tree. After hypoxia the number of dendritic fibres compared with the controls was smaller in the region of the basal dendrites (P less than 0.01) and in the preterminal and terminal branches of the apical dendrites (P less than 0.05). Spine density after hypoxia was lower than in the controls on the basal dendrites (P less than 0.01) and, except for the terminal part, on the apical dendrites (P less than 0.01). The dendritic spines of experimental animals were found to be short, club-shaped and thick, while in the controls they were long, thin and sometimes branched. Prolonged postnatal hypoxia discernibly interfered with the process of formation of the microstructure of the hippocampus. Uneven restriction of the receptive field of the neurones and the suggested alteration in the transmitting characteristics of the spines might be the cause of some of the functional changes previously described in animals after hypoxia.

Aging↗