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G Kh Merzhanova

Publications and source records attributed to G Kh Merzhanova.

At least 19 recordsLinked to original sources
PubMed2005

Organization of frontohippocampal neuronal networks in cats in different types of directed behavior.

Food-related operant conditioned reflexes to light were developed in four cats on the basis of the "active choice" of reinforcement quality: short-latency pedal presses were reinforced with a mixture of meat and bread, while long-latency presses were reinforced with meat. Animals showed differences in their behavioral strategies: two preferred long-latency pedal presses (animals with "self-control"), while the other two preferred short-latency pedal presses ("impulsive" animals). At the second stage of the study, animals of both groups were retrained to a short-delay (1 sec) conditioned operant food-related reflex in response to light with meat reinforcement. Chronically implanted Nichrome semimicroelectrodes were used to record multicellular activity in the frontal cortex and hippocampus (field CA3). The interaction of neighboring neurons within the frontal cortex and hippocampus (local neural networks) and neurons of the frontal cortex and hippocampus (distributed frontohippocampal and hippocampofrontal neural networks) were assessed by statistical cross-correlation analysis of spike trains with an analysis epoch of 100 msec. The frontal and frontohippocampal neural networks had different modes of functional organization in the simplified task for the animals of the two groups. However, intergroup differences in local networks of the hippocampus persisted in conditions of the simplified task lacking the requirement for the animals to select the quality of the reinforcement, indicating the likely genetic determinacy of these networks.

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PubMed2004

Interneuronal frontohippocampal interactions in cats trained to choose on the basis of reinforcement quality.

Six cats were trained to food-related operant conditioned reflexes to light using the "active choice" of reinforcement method: short-latency pedal pressings were reinforced with meat and bread, while long-latency responses were reinforced with meat. Animals were divided in terms of their behavioral strategies: four preferred long-latency pedal pressings (the "self-controlled" group), while the other two preferred short-latency pedal pressings ("impulsive" animals). Implanted Nichrome semimicroelectrodes were used to record multicellular activity in the frontal cortex and hippocampus (field CA3). Interactions of neighboring neurons within the frontal cortex and the hippocampus (local neuronal networks) and between frontal cortex and hippocampal neurons (distributed neural networks in the frontohippocampal and hippocampofrontal directions) were assessed by statistical cross-correlation analysis of spike series with analysis epochs of 100 msec. The number of cross-correlational connections between the discharges of neurons in both local and distributed networks were significantly greater in the group of animals demonstrating self-control, i.e., preferring long-latency pedal pressings to receive the more valuable reinforcement. It is suggested that the predominance of functional interneuronal connections in the local networks of the frontal cortex and hippocampus and in frontohippocampal distributed networks in animals operating in the self-control regime as compared with impulsive animals demonstrates the dominant role of these informational structures in the organization of self-controlled behavior.

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PubMed2003

Local and distributed neural networks and individuality.

The functional organization of local and distributed neural networks was studied in cats with different individual typological features of voluntary behavior. Stable behavioral characteristics were assessed using an individually varying selection of a larger (better) food reinforcement depending on the delay time in the operant motor response. Judging from the organization of interneuronal interactions, the decisive role in producing the choice of response is played by influences from hypothalamic and amygdalar motivational structures on the anterior parts of the neocortex, which was typical of rapidly-responding ("impulsive") cats, and interactions between frontal cortex and hippocampal systems in animals which delayed pedal pressing to receive the preferred food, i.e., animals with "self control."

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PubMed2003

Organization of neural networks in the neocortex.

Implanted semimicroelectrodes were used in conscious cats to record spike discharges from groups of close-lying neurons, i.e., multineuron activity, in the deep layers of the frontal and motor areas of the cortex at different levels of food motivation. Spike activity was extracted from 4-7 neurons and interneuronal interactions were studied by cross-correlation analysis between neighboring neurons in each zone (local networks) and between neurons in two zones (distributed networks) with analysis epochs of 0-100 msec. The results showed that neurons in local networks can be divided into two subgroups: neurons with high-amplitude spikes and a predominance of output (divergent) connections and neurons with low-amplitude spikes and a predominance of input (convergent) connections. Local networks are based on powerful monosynaptic connections (with delays of up to 2 msec) between large and small neurons. Most connections in distributed networks were between small neurons in local networks of the frontal cortex and large neurons in local networks in the motor cortex. Food deprivation for 24 h mainly affected late (with delays of 2-100 msec) cross-correlation interneuronal relationships in both local and distributed networks.

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PubMed2001

[Local and distributed neuronal networks and individuality].

To estimate stable behavioural peculiarities, an individual varying choice of greater or better appetite reinforcement depending on the time of instrumental motor response was used with cats. A decisive role in realisation of the response choice is played by the influence of motivational structures of hypothalamus and amygdala on formal areas of neocortex typical for "impulsive" (fast reacting) cats, and interaction of the frontal cortex--hippocampus system for the animals with delayed pressing of the lever to obtain their preferred food, i.e. manifesting the ability of "self-control".

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PubMed2000

[Functional organization of local neuronal networks in the cat neocortex. Dependence on the food motivation].

The multiple unit activity (MUA) from clusters of adjacent neurones in deep layers of the frontal and motor cortex was recorded in alert cats with different levels of alimentary motivation. Up to 7 spike trains were selected from the MUA. Neurones in the local circuits could be divided into 2 groups: large neurones with prevailing divergent characteristics, and small neurones with prevailing convergent characteristics. A 24-hour food deprivation altered the cross-correlation interneuronal connections with a time delay within the range of 2 to 100 ms.

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PubMedDate not supplied

Organization of network properties of cells in local and distributed neuronal networks of the brain of cats.

The network properties of neurons of the visual and motor cortex and of the lateral nucleus of the hypothalamus were investigated on the basis of identified interneuronal interactions, using the cross-correlation method of analysis, in cats with developed alimentary conditioned instrumental reflexes to light. The varied organization of the network properties of cortical neurons in the organization of local and distributed neuronal networks was demonstrated, namely: the predominance of divergent properties over convergent properties for large cells in local networks and the leveling out of these relationships in distributed networks. The neurons of the lateral nucleus of the hypothalamus had an equal representation of convergent and divergent properties in the organization of local and distributed networks. The network properties of neurons of the cortical and subcortical structures were manifested in the background, following the development of conditioned reflexes, and during extinction. Only the small cells of the visual cortex were functionally dependent and changed the relationship of network properties in local networks during the extinction of conditioned reflexes.

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PubMedDate not supplied

Cortical multineuronal activity in dogs with defensive instrumental conditioned reflex.

For the first time in dogs with semi-microelectrodes chronically implanted in the motor and somatosensory region of the cortex, background multineuronal activity (MNA) was recorded over the long term followed by an amplitudinal discrimination from the MNA of impulse series presumably belonging to cells of large, medium, and small size was performed. The presence of close synergistic functional connections, particularly significant during the avoidance conditioned reflex and its extinction, was established by determining the correlation coefficient (CC) between the impulse flows of these neurons. In trained animals the highest CC values were observed between neurons with a small and medium spike amplitude. The network properties of identified neurons were studied by constructing histograms of cross interval relationships. The connections established were of primarily a unilateral, excitatory character.

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PubMedDate not supplied

Time organization of frontal-motor cortex interneuron interactions in the cat neocortex in conditions of different levels of food motivation.

Studies were carried out in conscious cats with recording of multicellular activity in moderate hunger and after 24-h food deprivation. Cross-correlation analysis was used to assess statistical interneuron interactions between closely-located neurons in the frontal and sensorimotor regions of the neocortex (local networks), and between the cells of these regions (distributed networks). One-day food deprivation increased the number of interactions formed within both local and distributed neuron networks. Increases in intercortical connections between the frontal and motor regions was seen at all time intervals studied (0-100 msec), though the most significant changes occurred at time intervals of up to 30 msec.

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PubMedDate not supplied

Interneuron relationships in the basolateral amygdala in cats treated to select food on the basis of quality.

Cats were initially trained to make operant conditioned food responses to light by an "active selection of reinforcement" method. Provision of low-quality (a mixture of meat and bread) or high-quality (meat) reinforcement depended on the animal pressing a pedal in response to switching on a light with a short (1 sec) or long (10 sec) delay. Some animals responded to long delays--group I, animals with "self control," while others responded with short delays--group II, "impulsive" animals. Implanted semimicroelectrodes were used in chronic experiments to record multineuron activity in the basolateral amygdala. Cross-correlation analysis was used to study interneuron interactions in the spike discharges of individual neurons, extracted from multineuron activity. The numbers of interneuron interactions were significantly higher in "impulsive" cats of group II in all behavioral situations than in animals with "self control," and were dominated in "impulsive" animals by the shortest connections, with latencies of 0-30 msec. The largest numbers of connections in both groups were seen on omission of the conditioned pedal-pressing movement response, i.e., when the reinforcement selection task was more difficult. These data indicate that the basolateral amygdala should be regarded as a structure determining the individual typological characteristics of the animals' behavior.

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PubMedDate not supplied

Neuronal manifestation of two-way connections in conditioning.

Neuronal characteristics of two-way conditional connections were studied in chronic experiments with alert cats during different types of alimentary conditional reflexes. Single unit and multi-unit activities were chronically recorded in the visual and motor cortex and the lateral hypothalamic nucleus. Cross-correlational analysis of neuronal impulse trains was used to characterize the organization of neuron groups in brain structures involved in the formation of a conditional reflex. The experimental data showed an increase in the number of neuronal two-way connections after learning in all three investigated coordinations: visual-motor, visual-hypothalamic, and motor-hypothalamic. With visual-motor interneuronal coordination, the strengthening of two-way connections was due to the enhancement of connections from the motor to the visual neuron (backward connections); with visual- and motor-hypothalamic coordination, the number of interneuronal connections was equal in both directions. In all investigated coordinations, the analysis of the temporal parameters of the interactions between the neurons of different groups showed a dependence of the conditioning procedure on delays of up to 30 ms and a dependence of the motivational state on the interval range of 90-100 ms. The polyfunctional and polycomponent character of two-way neuronal connections in conditioning can be inferred from these data. Evaluation of the activity of neurons of different brain structures suggests the specific organization of intracortical and cortical-subcortical integrity in learning.

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PubMedDate not supplied

Network activity in neurons of the motor and prefrontal areas of the cortex in trained cats in conditions of systemic administration of m-cholinoreceptor blockers.

Experiments on five cats already trained to an operant conditioned food-procuring reflex to light were used to study the network activity of cells in the frontal and motor areas of the cortex accompanying disruption of conditioned reflex behavior in conditions of systemic administration of m-cholinoreceptor blockers. The activity of cortical neurons and their network properties were assessed using auto- and cross-correlation histograms. Doses of central m-cholinoreceptor blockers (the non-selective blocker scopolamine and the relatively selective m1-cholinoreceptor blocker trihexyphenidyl) disrupted performance of the operant motor reflex but had no effect on the appearance of contextual behavior and responses to switching on of the conditioned signal (standing up, elevating the paw). This was accompanied by 1) changes in the patterns of neuron activity in the moor and frontal areas of the cortex, with increases in train, rhythmic, and rhythmic train activity in cortical cells; 2) appearance of synchronicity in the operation of cortical neurons; 3) decreases in the numbers of direct interneuronal connections in the motor and frontal areas of the cortex and in the numbers of connections between these structures.

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PubMedDate not supplied

[The interrelations between neurons of the amygdala and hypothalamus during conditioning with selection of food reinforcement quality in cats].

Three cats were subjected to appetitive instrumental conditioning to light by the method of the "active choice" of the reinforcement quality. The short-delayed conditioned bar-pressings were reinforced by bread-meat mixture and the delayed response by meat. The animals differed in behavior strategy: two animals preferred bar-pressing with long delay (the so-called "self-control" group) and one animal preferred bar-pressing with short delay (the so-called "impulsive" group). The multiunit activity of the basolateral amygdala and nucleus lateralis of the hypothalamus was recorded through chronically implanted nichrome wire semimicroelecrodes. The interactions between the neighboring neurons in the lateral hypothalamus and basolateral amygdala (within the local neuronal network) and between the neurons of the basolateral amygdala and lateral hypothalamus (distributed neuronal networks in the direction amygdala--hypothalamus and vice versa) were evaluated by means of statistical crosscorrelation analysis of spike trains. The crosscorrelational interneuronal connections in the delay range of 0-100 ms were examined. It was shown that the number of crosscorrelations between the discharges on neurons both in the local networks of basolateral amygdala and distributed networks was significantly higher in "impulsive" cats. In both groups of animals, the percentage of crosscorrelations between neighbouring neurons in the local networks of the lateral hypothalamus was similar. We suggest that the local networks of the basolateral amygdala and amygdalar-hypothalamic distributed neuronal networks are involved in the system of brain structures which determine the individual features of animal behavior.

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PubMedDate not supplied

[The role of muscarinic cholinoreceptors in the retrieval of the instrumental food conditioned reflex in cats].

It was demonstrated in cat experiments that impairment of the retrieval of appetitive instrumental conditioning observed after systemic administration of antagonists of muscarinic central cholinoreceptors scopolamine (a nonselective M1 antagonist) and trihexyphenidyl (relatively selective M1 antagonist) could be connected with central and peripheral side effects of these antagonists. It was established that in case of the absence of side effects (low doses of trihexyphenidyl, 1 mg/kg) the blockade of M1-cholinoreceptors led either to selective fall-off of the motor instrumental reaction with in the presence of contextual behavior and other conditioned reactions or the appearance of errors that seemingly was indicative of the disturbance of triggering and realization of the motor program as the most important component of conditioning performance. The systemic injection of trihexyphenidyl (10 mg/kg), scopolamine (0.03 and 0.06 mg/kg) and nonselective peripheral antagonist methylscopolamine (0.03 mg/kg) led to changes in the general functional state (disorders in the emotional and motivational sphere), the expression of which depended on the individual sensitivity to anticholinergic drugs. The disturbance of CR retrieval observed in parallel with side reactions was characterized by a complete cessation of conditioning and apparently was not associated with memory deterioration.

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PubMedDate not supplied

[Cooperative activity of motor and frontal cortex neurons in trained cats systemically administered M-cholinoreceptor blockers].

It was shown previously that peripherally administered antagonists of the central 1 M-cholinoreceptors led to a selective impairment of bar-pressing response in a food-reinforced operant conditioned task but did not alter contextual behavior and functions such as motivation, perception, and locomotion. To obtain information about the central mechanisms of the conditioning impairment, we recorded simultaneously the extracellular multiunit activity from the frontal and motor neocortical areas of five cats trained to acquisition criteria in a food-reinforced operant conditioning task. Multiunit recordings were performed drur 1) normal conditioning; 2) conditioning during subcutaneous administration of muscarinic antagonists scopolamine (0.03 mg/kg), trihexyphenidyl (1 mg/kg), and methylscopolamine (0.03 mg/kg). Autocorrelation analysis showed that scopolamine and trihexyphenidyl but not methylscopolamine led to a significant increase in the tendency of cortical cells to fire in a cyclic way (i.e., the shift of the firing pattern from a single-spike discharge to burst, rhythmic, or rhythmic-burst discharge) both in the motor and frontal areas. Cross-correlation analysis showed that the bursting and rhythmic-bursting cells synchronized their activity within and (in a number of cases) between the cortical areas. These changes in the neuronal activity within the motor cortex and frontal cortex were accompanied by a significant decrease in the functional connectivity both inside and between the cortical areas in parallel with selective impairment of the conditioned response.

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