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Biomedical subjects

K N Dudkin

Publications and source records attributed to K N Dudkin.

At least 19 recordsLinked to original sources
PubMed2000

[Effect of prenatal emotional-pain stress on the status of interphase chromatin in neurons of the rat developing brain with various excitation of the nervous system].

A short-term emotional-painful stress, experienced by pregnant rat females differing in threshold of excitability of their nervous system, was used to assess the state of interphase condensed chromatin and C-heterochromatin of neuron nuclei in developing brains of 16-17 day old embryos. To reveal relationships between the genetically determined excitability of rats and the state of interphase chromatin in their neuron nuclei a computer information system has been used that enabled us to classify the neuronal nuclei according to their specific DNA image cytometry features. The results indicate an obvious relationship between excitability of the nervous system and structural-functional state of the neuronal interphase chromatin.

Animals↗
PubMed2000

[The role of the prefrontal and parietal cortex in learning and memory in monkeys].

Removal of the 7th field of parietal cortex and sulcus principalis of prefrontal cortex did not affect learning processes for images with such properties as spatial frequency, orientation, geometrical form, but worsen learning characteristics in visual differentiation of spatial information making the learning processes unstable, longer and below the 85% level. Removal of sulcus principalis also affects learning of differentiation among various colour stimuli. The short-term memory in these monkeys are also much worse than in intact animals. A scheme of learning involving interacting sensory and cognitive processes controlled by motivation system, is proposed.

Animals↗
PubMed1999

[An information system for automated cytogenetic image processing: analysis of interphase chromatin of nerve cells of embryonic brain of rats with varying nervous system excitability].

To reveal a relationship between the genetically determined excitability of rats and the structural-functional chromosome organization in their neurone nuclei a computer information system has been developed to classify the neurone nuclei according to their specific DNA image cytometry features. The nuclear features, such as size, shape, and DNA content, are calculated, along with features describing characteristics of chromatin with the nucleus. The neural and glial cells are separated according to the rule based expert system approach with the use of a nuclear feature vector. The DNA image processing is performed and a feature vector consisting of normalized measures of the neurone nucleus chromatin region descriptors is extracted. The results indicate a relationship between the peculiarities of the nervous system and the structural-functional state of the chromosomal apparatus.

Animals↗
PubMed1999

[Effect of the NMDA receptor antagonist on parameters of delayed visual differentiation and rearrangement of the impulse activity of neurons in visual and prefrontal cortices in monkeys].

With the aid of a multichannel leads the unit activity was recorded in the 17th and 8th cortical fields along with registering behavioural data in Rhesus monkeys. Multi-factor variance analysis revealed that the 2-amino-5-phospho-valeric acid (APV) effect involved a significant worsening of the monkeys' behavioural characteristics: duration of the short-term memory shortened (2-4-fold), motor reactions' time increased, and the changes of cognitive characteristics were always followed by significant rearrangements of the unit activity in the above areas. The data obtained suggest that these cognitive dysfunctions are due to a desynchronisation of unit activity in different areas of the cortex including the neuronal assemblies maintaining the short-term memory mechanisms associated with the glutamatergic structures.

Animals↗
PubMed1999

[Neurophysiological correlates of delayed visual differentiation in monkeys: effect of location of the NMDA-receptor intracortical blockade].

A multi-factor variance analysis revealed that the 2-amino-5-phosphonovalerian acid (APV) effect was manifested in monkeys by a decrease in the number of correct responses entailing a two-fold shortening of the short-term information storage, as well as by an augmentation of the motor responses' time. The correct responses' probability depended on the APV diffusion localisation in the cortex whereas the motor responses' time did not depend on it. The APV effect was accompanied by a desynchronisation of the unit activity in fields 46 and 17. Neurophysiological correlates of cognitive functions, are discussed.

2-Amino-5-phosphonovalerate↗
PubMed1998

[Dependence of learning characteristics on visual object properties in Rhesus macaca by bilateral removal of the 7th field of the parietal cortex].

Removal of the rhesus monkey parietal cortex 7th field exerted no effect on learning processes involving visual discrimination of images united in their colour and geometrical form, but the learning of differentiating the spatial information did suffer. The data obtained suggests that, in the process of learning visual differentiation, spatial differentiating signs are formed, the process involving neuronal structures of the 7th field of the inferior cortex. Removal of the 7th field disrupts mechanisms of the body scheme assession and egocentric orientation resulting from visual-vestibular interrelationships.

Animals↗
PubMed1998

[The model of adaptive primary image processing].

A computer model of adaptive segmentation of the 2D visual objects was developed. Primary image descriptions are realised via spatial frequency filters and feature detectors performing as self-organised mechanisms. Simulation of the control processes related to attention, lateral, frequency-selective and cross-orientation inhibition, determines the adaptive image processing.

Models, Neurological↗
PubMed1997

[The dependence of the characteristics of visual short-term memory in monkeys on the spatial properties of the images].

Specifics of spatial components induced a shorter information storage and more obvious motor responses as compared with other visual attributes of the stimulus (shape or colour) in rhesus monkeys. The findings suggest that the short-term memory mechanisms involve visual information processing in the visual system as well as spatial discriminative features maintained by the parietal cortical mechanisms involving visual-vestibular interactions.

Animals↗
PubMed1997

[The specific nature of the cholinergic mechanisms of short-term memory in monkeys for different types of visual information: the characteristics of the effect of amizil].

Short-term storage of visual information in monkeys seems to be determined by a set of cholinergic mechanisms, each of them dealing with a certain type of visual objects. These mechanisms are involved into the visual information processing and forming spatial discriminative features caused by the visual-vestibular interaction.

Animals↗
PubMed1995

[The neurophysiological correlates of improvement in the cognitive characteristics of monkeys with modification of the NMDA-ergic structures of the prefrontal cortex].

The effect of the NMDA glutamate agonist on cognitive characteristics and short-term memory (SM) was studied in rhesus monkeys. The NMDA effect manifested itself in doubling the SM term and in changing of the unit activity in the prefrontal cortex. The NMDA also induced a considerable increase in the cross-correlation coefficients between the unit responses in visual and prefrontal cortex. The data obtained suggest that the glutamatergic structures of prefrontal cortex take part in the processes of visual recognition and the SM in monkeys. The effect seems to improve the short-term memorizing of a visual information.

Animals↗
PubMed1995

[Synchronization processes in the mechanisms of short-term memory in monkeys: the participation of cholinergic and glutaminergic cortical structures].

Administration of amysil blocking M-cholinoreceptors, and APV the duration of short-term storing of information was decreased whereas the motor response time increased. This was followed by a considerable desynchronisation of the unit activity. The NMDA and APB improved the characteristics of the short-term memory. The role of synchronisation of the information processes in the short-term memory mechanisms and participation of cholinergic and glutamatergic systems in them, are discussed.

Acoustic Stimulation↗
PubMed1994

[The neurophysiological correlates of the processes of decision making in the cerebral cortex during visual recognition in monkeys].

In behavioral experiments on monkeys tested for a delayed visual differentiation of different colours stimuli, neuronal pools were recorded simultaneously in the visual, prefrontal and inferotemporal cortex. Wrong motor responses were always followed by considerable readjustments of the unit activity patterns whereas in right decisions a synchronisation and a cross-correlation occurred between neuronal pools. Possible mechanisms of the decision making and the reasons for the desynchronisation in wrong responses, are discussed.

Acoustic Stimulation↗
PubMed1994

[The dynamic impulse activity of the neocortical neurons in monkeys with the task of visual recognition after short-term oxygen starvation].

During a 2.5-min. hypoxia in monkeys, a rearrangement of the unit activity occurred in the visual and prefrontal cortex. Following this, the motor response in delayed visual spatial reaction tack did not restore during several hours. The rearrangement involved appearing of sequential phases of hyperactivation and inhibition. Duration of the posthypoxic inhibition and ratio of posthypoxic hyperactivation frequencies to the background one were significantly greater in the prefrontal cortex than in the visual one.

Acoustic Stimulation↗
PubMed1993

[The participation of the cholinergic structures of the prefrontal and inferotemporal cortices in visual recognition processes in monkeys].

Characteristics of visual recognition were impaired by amysil influence in monkeys. This was accompanied by a considerable activation of unit activity in the prefrontal cortex. Amysil induced a considerable drop in the cross-correlation coefficients between simultaneous responses of neuronal populations in prefrontal and inferotemporal cortex.

Acoustic Stimulation↗