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Biomedical subjects

N O Timofeeva

Publications and source records attributed to N O Timofeeva.

At least 19 recordsLinked to original sources
PubMed1984

[Brain function and higher nervous activity].

Some actual problems of higher nervous activity have been analysed on the peculiarities of brain states in the course of different types of conditioning and reactivity of the nervous structures which depend on the brain state have been considered. A concept of brain state as a specific mechanism of each temporal connection forming during the learning process has been formulated for the first time. The authors suggest that the brain represents the dynamic system with changeable structure which reveals itself in multitude nervous set constellation during various types of activity. This concept is presented to be the theoretical basis for integral evaluation of functional capacities of central nervous system.

Animals↗
PubMed1984

[Integrative properties of parietal cortex neurons of rabbits during the switching of heterogeneous classical conditioned reflexes].

The impulsive activity of parietal cortex neurons of rabbits during the elaboration and specialisation of switching-over of alimentary and defensive conditioned reflexes has been studied. There are changes of parietal cortex neurons activity correlated with the stages of switching-over elaboration. The significant differences of the background neurons activity and neurons response to the conditional signal during alimentary and defensive conditioned reflexes have been established. The dominant motivation influences the neurons activity by modulation of background and conditioned activity of neurons. The integrative properties of neurons investigated in switching-over situation are revealed in their ability to summarize the excitation coming to the same sensory input with excitation from different motivational and reinforcement systems.

Acoustic Stimulation↗
PubMed1984

[Hippocampal neuronal activity in the switching of heterogeneous classical conditioned reflexes].

The impulsive activity of hippocampal neurons during the elaboration and specialisation of switching of the alimentary and defensive classical conditioned reflexes has been studied. The associative changes of the phasic and tonic neurons activity have been shown to be the neurophysiological background of the tonic and phasic mechanisms ensuring the conditioned switching. The differences between the tonic activity and the neuron response to the conditioned stimulus during different conditioned activity have been established. The difference of the neuronal activity to the conditioned stimulus during the change of its signal meaning is due to a great extend of the tonic activity. Motivation is supposed to play a leading role in the changing of the neurons activity under the conditioned switching.

Animals↗
PubMed1982

[Analysis of neuronal mechanism of conditioned switching-over].

Activity of hippocampal neurones was studied in unrestrained rabbits during switching-over of alimentary and avoidance conditioned reflexes. It was shown that the neurophysiological mechanism of switching-over is provided by phasic and tonic associative components of neuronal responses. Significant differences were established in neuronal tonic activity and phasic responses to the conditioned signal during heterogeneous conditioned activity. Dynamics of the tonic activity and the phasic response was revealed during switching-over elaboration. The determining role of the tonic activity in the modification of the phasic response to the conditioned stimulus following the change in its signal significance was established. The motivational excitation plays a leading role in the change of tonic activity and neuronal response to one and the same signal in the process of switching-over. It is suggested that process underlying the switching-over is based on specific kind of neuronal plasticity, the ability to form different responses to one and the same conditioned signal with different kinds of reinforcement.

Animals↗
PubMedDate not supplied

[The activity of hippocampal neurons during several types of behavior].

The activity of 87 hippocampal units and the EEG (field CAI) were studied in unrestrained rabbits during calm and active alertness and at different stages of sleep. Correlation has been established between the characteristics (mean frequency and the pattern) of unit firing, EEG and the animal's activity. For most of the neurones, fixed values of mean frequency and the discharge pattern corresponded to a definite functional state. With transition from sleep to alertness, 63.6% of the units became active, 29.1% were inhibited, and the rest of the units changed the firing pattern only. The cells which became activated during awakening, showed a reduced firing frequency during a more profound sleep and higher discharge frequency during the paradoxal phase of sleep, while the inhibitory cells revealed reverse dynamics of discharge frequency. In a state of alertness, the most pronounced shifts in firing activity were observed in 33.3% of the nerve cells at orienting investigating behaviour, in 27.1%, during attention reaction, in 22.9% at some kinds of movement, and in 16.7%, in the course of feeding and drinking. A conclusion has been drawn that the role of the hippocampus in achieving different behavioral reactions is probably to a great extent determined by its participation in setting up a level of the brain central tone, specific for each state.

Animals↗