[Does Impulsivity Affect a Long-term and Working Memory in rats?].

In the present paper usingthe method of delay discounting three groups of animals were discovered: a) those that at choice between immediate weak and delayed strong rewards have chosen an immediate reinforcement (high impulsive rats); b) those that were able to inhibit its own behavior and get the delayed reinforcement (low impulsive rats); and c) the rats with both types of reactions. In the water maze the different groups of rats did find a hidden platform for different time, swum various distance and with different speed. The differences however were significant only at overall comparison (for all days and trials) of the above mentioned parameters of the water maze learning. ANOVAs Group x Days, Group x Trials, and Groups x Days x Trials interactions were insignificant. The data obtained indicate that the difference between groups was appeared evidently due to the difference in general motor activity, rather than difference in their cognitive abilities assessed by reference and working memory tasks.

[Impulsive Choice Improves the Cue Memory at an 8-arms Radial Maze Learning in Rats].

At the process of learning in an 8-arm radial maze the impulsive animals found the reinforced arms and ate the pellets faster, than self-control and ambivalent rats. They committed less working memory errors at the cue memory task, though there was no difference in the rate of learning and a number of errors of reference memory in animals of different groups. During reversion learning at the change of reinforced arms on unre- inforced, and vice versa, the impulsive animals spent less time to enter into the reinforced arms compared to other groups. They had fewer errors of cue working and reference memory, but the rate of learning was the same as in other groups. The date obtained indicate that in the impulsive rats in comparison with the other groups of animals are stronger the general motor activity and better the working memory.

[Single and Network Neuron Activity of Subthalamic Nucleus at Impulsive and Delayed (Self-Control) Reactions in Choice Behavior].

During our experiments on cats was investigated the subthalamic neuron activity at different types of behavior in case of reinforcement choice depending on its value and availability. In chronic experiences the multiunit activity in subthalamic nucleus (STN) and orbitofrontal cortex (FC) has been recorded. Multiunit activity was analyzed over frequency and network properties of spikes. It was shown, that STN neurons reaction to different reinforcements and conditional stimulus at short- or long-delay reactions was represented by increasing or decreasing of frequency of single neurons. However the same STN neu- rons responded with increasing of frequency of single neuron during expectation of mix-bread-meat and decreasing--during the meat expectation. It has been revealed, that the number of STN interneuron interactions was authentic more at impulsive behavior than at self-control choice of behavior. The number of interactions between FC and STN neurons within intervals of 0-30 Ms was authentic more at display impulsive than during self-control behavior. These results suppose that FC and STN neurons participate in integration of reinforcement estimation; and distinctions in a choice of behavior are defined by the local and distributed interneuron interactions of STN and FC.

[Effect of Agonists and Antagonists of α2 Adrenergic Receptors on Choice of Reinforcement Value in Rats with Different Levels of Impulsivity].

The influence of drugs, agonist (clonidine) and antagonist (yohimbine) of α2-adrenergic receptors 5-HT2 on the behavior of rats tested by the method of choice to the value of reinforcement was investigated. Based on the selection of a rat the pedal for immediate poor and delayed valuable reinforcement rats were divided into 3 groups. Rats, in most cases, choosing valuable delayed reinforcements were classified as low-impulsive, those who mainly chosen poor immediate reinforcement to the high-impulsive group. Rats who were not able to determine, was ambivalent group. Administration (i.p.) of the α2-adrenergic receptors agonist clonidine resulted in a reduction of the select valuable delayed reinforcement by low-impulsive animals and increasing the number of missing responses of pressing the pedal in high-impulsive animals. Clonidine also reduced the latency of nose-poking in all groups of animals. The antagonist of these receptors yohimbine did not cause changes in the choice of the reinforcement in all groups of animals. At the same time yohimbine caused a significant reduction in the number of missing responses. The results suggest that the effect of drugs used in this work on α2-adrenergic receptors depends on the individual feature of rats, in particular from high and low degree of impulsivity.

[Effect of agonists and antagonists of 5-HT2 receptors on rats with different choice of reinforcement value].

The influence of drugs, agonist (DOI) and antagonist (ketanserin) ofserotonin receptors 5-HT2 on the behavior of rats tested by the method of choice to the value of reinforcement was investigated. Depending on their preferences in food reinforcement rats were divided into self-control (choosing more valuable, delayed reinforcement) and impulsive (low value, immediate reinforcement) groops. An hour before the test animals were administrated i.p. DOI and ketanserin at a dose of 0.2 mg/kg. Evaluated parameters of rat behavior: number of clicks on a particular pedal, the latencies and the number of omitted responses. The administration of ketanserin resulted in a statistically significant decrease in the choice of low-value immediate reinforcement of impulsive rats, and did not statistically significant alter the behavior of self-control animals. After the administration of DOI no statistically significant changes in the choice of reinforcement were observed in the groups of impulsive and self-control rats. But the study of the effect this drug in tote without division into typological groups the decreasing in impulsivity was revealed. In some cases DOI reduced the number of missing responses, and ketanserin--reduced the latency of response.

[Neuron activity of cortex and striatum at animals in the situation with "right of choice" of reinforcement].

In behavior model of "right of choice" of value of appetitive reinforcement animals have classified in self-control, ambivalent and impulsive groups based on significant distinctions in displays of short delayed or long delayed reflexes. The organization of functional cross correlation interneuron interactions in frontal, visual, motor cortical areas and dorsal part of caudatus have estimated at realization short delayed, long delayed reflexes and errors. Similarity and distinctions in the organization of network activity were analyzed. It was shown that only interneuron relation of visual cortex and caudatus were similar for impulsive and self-control animals. When comparing the "impulsive" and "ambivalent" animals similarity was found in the network activity of neurons of visual, motor cortex and dorsal part of caudatus. The differences in the network activity in the frontal cortex were identified between animals of all three groups during realization of long delayed reflexes.

[Effect of the selective ligands 5-HT(1A) receptors administration on the impulsive and self-control behavior in rats].

The influence of drugs, agonist and antagonist of serotonin receptors 5-HT(1A) on the behavior of rats tested by the method of choice to the value of reinforcement was investigated. Depending on their preferences in food reinforcement rats were divided into self-monitoring (choosing more valuable, delayed reinforcement) and impulsive (low value, immediate reinforcement). An hour before the test animals were administrated i.p. agonist 5-HT(1A) receptors 8-OH-DPAT, [(+)-8-Hydroxy-2-(dipropylamino)tetralin] in a dose of 0.1 mg/kg or antagonist WAY-100635, [N-[2-[4-(2-Methoxyphenyl)-1-piperazinyl]ethyl]-N-2-pyridinylcyclohexanecarboxamide maleat salt] at a dose of 0.2 mg/kg. Evaluated parameters, such as number of clicks on a particular pedal, the latencies and number of omitted responses. The results showed that the administration of drugs to modify individual behavior parameters both groups of animals. The introduction of 5-HT(1A) agonist receptors in impulsive animals caused an increase in the number of clicks on the pedal for more valuable reinforcement, and administration of an antagonist did not have any significant effect to behavior.

[Ensemble activity of neurons in the visual, frontal, and sensorimotor cortices and dorsal striatum during actualization of behavioral program under conditions of strategy choice].

Unit and network activity of neurons in the visual, sensorimotor, and frontal cortical areas and dorsal striatum was investigated in cats under conditions of choice of the reinforcement value depending on its delay. The animals did not differ from each other in behavior. After immediate or delayed responses cats got low- or highly-valuable reinforcement, respectively. Single-unit activity in the visual and sensorimotor cortical areas and dorsal striatum was similar during performance of immediate and delayed responses. However, significant inhibition was observed in the frontal neurons during the delay period. The network activity of visual and frontal cortex displayed smaller number of interneuronal interactions during delayed responses as compared to immediate reactions. The network activity of neurons in the brain structures under study pointed to the interstructural interaction, but only during delayed reactions, steady interneuronal communication was observed between the frontal cortex and dorsal striatum. Thus, both types of estimation of cellular activity revealed differences in the ensemble organization during different types of behavior and showed specific reactions of neuronal ensembles.

[Effect of D1/D2 dopamine receptors agonists and antagonists on rats with different choice of reinforcement value].

The effects of D1/D2 dopamine receptors agonist (SKF, TNPA) and antagonist (SCH 23390, raclopride) on rat behavior, associated with the choice of the reinforcement value were investigated. Animals were divided into two typological groups--group of impulsive, choosing low-value immediate reinforcement, and self-control group, preferring valuable delayed reinforcement (paradigm delay-discount). The results showed that i.p. administration of D1/D2 receptors antagonists (SCH 23390 and raclopride) resulted in a statistically increase in the choice of pedals with immediate reinforcement of low value in animals of self-control group, without causing a change in the behavior of impulsive rats. Also, the increase in number of missed responses was obtained. When D1/D2 receptors agonists (SKF, TNPA) were administered no significant changes were observed in rats' behavior. However, we noted a trend to change the preferences in choosing pedals for reinforcements, which was different in the rats of two groups--the self-control rats showed a decrease of pressing the pedal to get valuable delayed reinforcements, while in impulsive animals, on the contrary, the number of elections pedal receive valuable reinforcements increased. Thus our results suggest the difference between the effects of dopamine in animals differing in their individual and typological characteristics.

[Network activity of frontal and motor cortex in situations of simple and difficult decision-making in cats].

The organization of frontal and motor cortex network activity in situations with simple (without a choice) and difficult decision-making when there is a possibility of behavior choice strategy is shown. At development of delay reflexes with one reinforcement (without a choice) animals did not differ on behavior and showed high criterion of right answers. The strategy of behavior of the same animals in the complicated situation, with "right" choice food reinforcement, was different and animals showed different abilities of problem solution. Distinctions in neuron ensembles organization of frontal and motor cortex in situations with simple and difficult decision-making was revealed. In difficult decision-making situation, the number of exciting interneuron interactions in motor cortex was decreased that assumed the organization of inhibition chains. In the same situation, frontal network activity was not changed, and the tendency to increase of these parameters was observed only in erroneous reactions.

[Effects of blockade of dopaminergic D1/D2 receptors on behavior of impulsive and self-controlled rats].

Selective antagonists of D1 and D2 receptors (SCH 23 390 and raclopride respectively) were injected to rats divided on the basis of preliminary experiments into groups of"self-controlled" (preference of valuable but delayed reinforcement) and "impulsive" (choice of less valuable but immediate reinforcement) animals. Number of omissions of reactions and their latencies were recorded. In "self-controlled" rats, both drugs increased the number of reactions for less valuable immediate reinforcement, i.e., increased impulsiveness, whereas practically did not change the behavior of "impulsive" animals. Introduction of SCH 23 390 to animals ofboth groups increased the number of reaction omissions the effect being stronger in "self-controlled" animals. Raclopride also increased the number of reaction omissions in "self-controlled" rats but only on the next day after the injection. In "impulsive" animals, both drugs increased the latencies of reactions.

[Individual typological differences in human behavior under conditions of reward choice assoicated with risk].

A choice between probability (100, 75, 50, 25, 10, 0%) and valuable reward were investigated in adult. In behavioral experiments, adult subjects put in a situation of a choice between greater, but risky prize and smaller, but received always, made the decision according to situational factors and specific features of character such as propensity to risk and care. In a situation of choice of behavioral strategy, subjects could be divided in "inclined to risk" and "careful". Tipologycal differences between groups were the greatest under conditions of 25% probability of getting a valuable reward. Probability prognosis was more efficient in persons "tended to risk", than in "careful" subjects. According to psychological tests, "impulsive" people appeared to be more inclined to risk than to cautiousness. For the group of persons that tended to cautiousness under conditions of 25% probability of getting a valuable reward, synchronism of EEG rhythms in the alpha and beta bands was revealed.

[Differences in behavior of impulsive and self-controlled rats in the open-field and light-dark tests].

The aim of the study was to reveal the relationship between impulsive behavior in rats, on the one hand, and locomotor activity and emotionality on the other hand. Rats were divided into groups according to their preference for reinforcements of different values. Animals that preferred valuable but delayed reinforcement in more than 60% of cases formed a self-controlled group, whereas rats that selected poor but immediate reinforcements in more than 60% of the cases were considered as impulsive. The two groups of animals were subjected to the "open field" and "light-dark" tests. The impulsive animals more quickly adapted to new surroundings and displayed more pronounced research activity as compared to the self-controlled animals. The level of anxiety was higher in the self-controlled group.

[Ensemble activity of visual and frontal cortex in the conditions of choice of different value food reinforcement in cats].

The method of "low choice" of food value reinforcement depending on delayed response to its reception demonstrated various strategy of behaviour, showing short or delayed responses of pressing pedal for reception of low or high value of food reinforcement. In trained cats, multiunit activity was recorded in investigated brain areas and functional interneuron interactions were subsequently analysed. Significant prevalence of interneuron interactions was revealed in "impulsive" animals in both cortical zones as well as intergroup differences during the pre-signal and signal periods in visual and frontal cortex.

[Individual prognostic behavioral features in dogs during the choice between probability and value of reinforcement].

A strategy and latency of choice between the probability (100, 50, 30, 20 and 0% probabilities were tested) and value (high and low) of the reinforcement were investigated in dogs. The greatest differences in dogs' behavior were observed under conditions of uncertainty when the valuable reinforcement was presented with probabilities from 50 to 20%. According to subjective evaluation of uncertain situation, dogs were divided into "inclined to risk" (more frequently choosing low-probable but valuable food) and "careful" (more frequently choosing high-probable but less valuable food). The choice of less probable reinforcement, especially under conditions of increasing uncertainty, was performed with longer latency that the choice of the 100%-reinforcement, which points to the strengthening of cognitive processes under conditions of a "difficult choice". The situation of uncertainty increased the emotionally negative state of the dogs (whimper, refusal of meal, etc.).

[Effects of blokade of the dopaminergic D1/D2 receptors on the single and network neuronal activity in the frontal and visual cortices and behavior of cats].

The results obtained at the levels of single and network neuronal activity in the frontal and visual cortices of cats with different types of behavior revealed features of activity of these structures in normal conditions and after local introductions of antagonists of DI/D2 receptors (SCH23390 and raclopride) into the n. accumbens and frontal cortex. Under the influence of the antagonists, long-latency reactions were characterized by a significant increase in the average frequency of neuronal activity in the frontal cortex, whereas in the visual cortex the average frequency decreased as compared to norm. At the same time, the network activity of the same neurons in the frontal cortex did not change but weakened in the visual cortex, which was expressed in a reduction of the number of neuronal interactions within the visual cortex and between the neurons of the frontal and visual cortices. Normally, during the long-latency conditioned reactions, the average frequency of single neuronal activity and the rate of neuronal interactions in the structures under study were significantly higher as compared to the loss of conditioned reactions. Administration of the dopamine antagonists did not change these features. The results suggest different dopamine modulations of the network activity of the cortical zones under study during the conditioned performance, which is expressed in responsiveness of the cortical projection of a trigger signal (the visual cortex) and visual-frontal networks generated in the course of training.

[Investigation of behavior of "impulsive" and "self-controlled" animals by the method of "emotional resonance"].

Rats divided into groups of "impulsive" and "self-controlled" animals by their preference of either high valuable but delayed or a low valuable but immediate food reward were studied by the method of "emotional resonance". It was shown that all rats of the "self-controlled" group choosing a high valuable although delayed reinforcement did not escape the defensive signals of another animal of the same species and for the most part of the trial time preferred to stay in the dark "house". The majority of animals belonging to the "impulsive" group (80%) spent more than a half of the time of the experiment in the bright compartment and thus saved a partner from electrical stimulation. The existence of some general mechanisms that underlie these two types of behavior is discussed.

[Study of impulsivity in rats under conditions of choice between food reinforcements of different values].

Rat behavior was studied under conditions "with the right to choose the values of reinforcements depending on the time delay of its receipt". Rats were placed in a chamber equipped with two retractable pedals, pressing one of which provided a small portion of food (1 pellet), and pressing the second pedal was followed by the delivery of more valuable food (4 pellets), but delayed reinforcement. Rats preferring small reinforcement without the delay were considered as "impulsive" and rats choosing more valuable delayed reinforcement were considered as "self-controlling". Influence of the delay duration and change in the level of motivation on the pedal pressing was studied in both groups of rats. Preference in the selection of the pedal, latency of pressing the pedal and the number of omitted reactions were estimated. It was found that "impulsive" animals more rapidly pressed the pedal and less frequently omitted trials than "self-controlling" rats. After the increase in the delay duration up to 7 seconds, rats stopped choosing the pedal with the delayed reinforcement. Increased food motivation shifted the behavior of rats to "self-control", whereas rats after feeding preferred less valuable immediate reinforcement.

Cooperative activity of neurons in the nucleus accumbens and frontal cortex in cats trained to select reinforcements of different value.

Results obtained at the level of the organization of interneuronal interactions of cells in the nucleus accumbens and frontal cortex revealed the features of the involvement of this component in "impulsive" and "self-controlled" behavior, consisting of an increase in bidirectional interactions between the structures of interest, accompanied by simultaneous reductions in the regularity of interactions with increases in "impulsivity" and decreases in "self-control." Long-latency reactions appearing only in "impulsive" animals were associated with decreases in the control of frontal cortex cells by the nucleus accumbens during the signal period, which correlated with the low activity of the network activity of the nucleus accumbens in these animals. Comparison of the patterns of frontal-accumbens interactions as the animals performed a single type of activity demonstrated that the connections in neuron pairs during the presignal and signal periods were similar, while significant differences in patterns were seen during the performance of different types of activity.

Organization of interneuronal connections in the nucleus accumbens in "impulsive" and "self-controlled" behavior in cats.

In behavioral experiments, cats placed in a situation of choosing between a high-value time-delayed and a low-value rapid food reinforcement elected to wait for the preferred reward (they demonstrated "self-control") or to obtain the worse reward quickly (they demonstrated impulsive behavior). On the basis of the selected behavioral strategy, the cats were divided into three groups - "impulsive," "ambivalent," and "self-controlled." Cross-correlation analysis was used to assess the linked activity of cells in the nucleus accumbens, which reflects the nature of interactions between close-lying neurons. In cats with self-control, interneuronal interactions appeared in a significantly larger proportion of cases than in impulsive cats. In combinations resulting in long-latency reactions, cats with self-controlled and impulsive behavior showed no significant difference in the occurrence frequency of interneuronal interactions. The numbers of interneuronal interactions were greater during erroneous responses as compared with correctly performed reactions in animals of the different groups. These data indicate a key role for the interrelated activity of nucleus accumbens neurons in organizing the pattern of long-latency responses typical of self-controlled behavior.