The intrinsic mechanisms underlying the maturation of programming sequential spikes at cerebellar Purkinje cells

Cerebellum is involved in the motion coordination and working memory, to which the programming of sequential spikes at Purkinje cells is essential. It is not clear about the intrinsic mechanisms underlying spike capacity and timing precision as well as their postnatal maturation. We investigated the programming and intrinsic property of sequential spikes at Purkinje neurons during postnatal development by whole-cell recording in cerebellar slices. Cerebellar Purkinje neurons demonstrate the increasing of spike capacity and timing precision, as well as the lowering of refractory periods and threshold potentials during the postnatal maturation. In addition, the correlation between spike parameters and intrinsic properties converts to be more linear. This postnatal plasticity of neuronal intrinsic properties improves the timing precision and capacity of spike programming at cerebellar Purkinje neurons.     

An orthoquinone isolated from Salvia aethiopis

A new orthonaphthoquinone diterpene has been isolated from Salvia aethiopis and given the trivial name aethiopinone. The structure of this natural     

Identification of catecholamines in the rat brain and mollusk tissues using semithin slices and retrograde staining

The suggested technique allows revealing the transport-specific dye (primulin) and catecholamine fluorescence simultaneously in the same cell of brain. Intense fluorescence is observed when brain tissue is quickly dehydrated and embedded in the epoxy resin. The same method is suggested for the identification of catecholamines in the embryonal and juvenile tissues of gastropod Lymnaea stagnalis (Mollusca Pulmonata) without using of primulin dye.     

Chromosome evolution in the owl monkey,Aotus

We have reported nine distinct karyotypes for Aotus, of four pelagic phenotypes, and suggest that this single species has undergone extensive subspeciation. We reconstruct the mechanism of chromosomal evolution and propose a hypothesis about the events of subspeciation in Aotus. We speculate that isolated groups of ancestral individuals living in several confined areas have separately accumulated a fusion or inversion pair as a result of inbreeding. A subsequent reassociation of descendants from these individuals led to the formation of offspring with mixtures of fusion or inversion pairs in their complements. They, in turn, radiated into different ecological niches accompanied by adaptive genetic changes and eventually gave rise to the present forms of Aotus distinguishable by their karyotypes, but not easily recognizable by ordinary taxonomic criteria.     

Modeling the process of problem-solving by associative networks capable of improving the performance

In this paper a model of neural network underlying arithmetic prblem-solving is described. Memory models of procedural memory, semantic memory, and working memory, which are necessary to represent the process of the problem-solving, are constructed within a framework of a model of associative processor, HASP, proposed by one of the authors (Hirai 1983). Performance of the model has been simulated on a digital computer. By memorizing primitive knowledge of addition of two digits such as 6+8=14 in the semantic memory and procedural knowledge for the control of the process of adding in the procedural memory, the model can perform addition of multiple numbers with multiple digits. By making explicit serial associations between consecutive procedural steps, the performance of the model can be impooved, because a current procedural step primes the next one. In addition, if a preceding procedural step is a subset of the next one, merging between the two steps occurs. The performance can be improved about 20% by these priming and merging. By memorizing incorrect procedures, the model can generate four kinds of bugs of addition which were observed in children's performance.This paper is a detailed version of the talk presented in CNN'87, but the model is slightly modified     

Thymine- and thymidine-dependence of Yersinia pestis mutants with altered thymidylate synthetase

Thymine- and thymidine-dependent mutants of Y. pestis strain EV-76 have been isolated and characterized. Obtaining Y. pestis thymine-dependent mutants in trimethoprim-containing media with full nutritional value in the presence of thymine and thymidine and the capacity of natural strains from the foci of infection in Transcaucasia and Mongolia to grow in such media indicate that Y. pestis has gene tpp controlling thymidine phosphorylase, but this enzyme is strongly suppressed under normal conditions. The capacity for its suppression under definite conditions and the degree of the activation of thymidine phosphorylase determine the realization of Thy and Thyd phenotypes in Y. pestis mutants under study, though both types of these mutants have a mutation damage of gene thy A coding the synthesis of thymidylate synthetase.     

The construction of a model of the envelope proteins of potex-group viruses

Amino acid sequences of coat protein of potato X-virus, aucuba potato mosaic, papaya mosaic and white clover mosaic have been comparatively studied. The results of this comparative study have become the basis for prediction of the secondary structure of the viruses and for construction of a model of potexvirus coat protein. The potexvirus coat protein was based on the three-layered arrangement of five alpha spirals. It is supposed that RNA molecule is within the protein subunit. Availability of common amino acid sequences in alpha spirals of coat proteins of TMV and potexviruses is established and this permits supposing their common origin.