[DOPAMINE STIMULATION AFFECTS MULTIPLE - FOOD - UNIT PREFERENCE IN RATS].

It has been shown that food seeking behavior in rats performing in different types of mazes is controlled by discrete reward pattern related to change in attractive properties of reinforcement and dopamine activity plays a critical role in motivation and food preference processing. The data obtained suggest that behavior as well as amphetamine effects revealed under the exposition of the discrete reward paradigm of learning may be involved in a common mechanism underlying food disorders and drug addiction in humans.

[EFFECTS OF URGENT RELEARNING ON THE PERFORMANCE OF THE SPATIAL TASKS].

Introducing of urgent relearning in radial maze, consisting of one or two shifts of reward position in raw without any gap between behavioral sessions, resulted to inability of animals to use optimal navigational strategy to find preferable reward in maze while keeping responding to int-ra-maze stimuli. Procedural introducing of time-out between tested behavioral sessions, which was accompanied by sleep generated naturally or induced by injection of neuropeptide ACTH 18-39, resulted to considerable improvement of relearning in radial maze as well as reducing per-severative behavior and attempts to refuse from responding. The data obtained demonstrate the important role of sleep for successful urgent relearning in radial maze and preventing possible neurological disorders.

[AN ANIMAL MODEL OF INTENTIONAL TREMOR].

The paper describes a model of intentional form of tremor developed in experiments in animals. Experiments with lesion of nucleus caudatus revealed the important role of this structure to regulate normal relationships between activity of reciprocal muscles under producing the non stereotypic forms of motor behavior. The model may be used to study the etiology and pathogenesis of intentional tremor as well as for preclinical testing of pharmacological drugs potentially perspective for correction of given form of diskinesia in humans.

Neuronal activity in the nucleus accumbens and hippocampus in rats during formation of seeking behavior in a radial maze.

Seeking behavior of rats in a radial maze with asymmetric reward was studied by means of synchronous recording of cell activity in the hippocampus and ventral striatum. The synchrony of cell activity in the hippocampus and nucleus accumbens was modulated by spatial position and reward; the important role in this synchronization can be played by theta rhythm. This is in line with the anatomical and physiological data on the convergence of hippocampal spatially organized positional and reward value information inputs from the amygdala and ventral segmental area to n. accumbens.

[A NEW APPROACH FOR FOOD PREFERENCE TESTING IN ANIMAL EXPERIMENTATION].

An article describes the original method allowing to study a mechanism of food preference related to the sensory properties of foods in animals. The method gives a good possibility to select the role of visual and orosensory signaling in food preference as well as to model the processes of physiological and pathological food and drug dependence in animal experiments. The role of discrete food presentation in the formation of the current motivations and food preferences was discussed.

[Diagnosis of attention-deficit hyperactivity disorder with a conditioned reflexes approach].

A new conditioned reflexes approach for assessment of attention deficit hyperactivity disorder (ADHD) symptoms in children has been used. Successful solving of behavioral task was related with the ability of children to shift their attention on spatially located sensory signals in radial labyrinth with asymmetric schedule of rewards. The innovative method developed gives a good possibility to increase the accuracy of ADHD evaluation in children of different age as well as to reduce the time for their behavioral testing.

Lesions of the medial shell of the nucleus accumbens impair rats in finding larger rewards, but spare reward-seeking behavior.

The goal of this study was to help better understand the importance of the nucleus accumbens (Nacc) in the processing of position and reward value information for goal-directed orientation behaviors. Sixteen male Long-Evans rats, under partial water deprivation, were trained in a plus-maze to find water rewards in the respective arms which were lit in pseudo-random sequence (training trials). Each day one reward arm was selected to deliver six drops of water (at 1 s intervals) the others provided only one drop per visit. After 32 visits, probe trials were intermittently presented among training trials. Here, all four arms were lit and offered the previously assigned reward. The rats rapidly learned to go to the highly rewarded arm. Six trained rats were given bilateral electrolytic lesions in the Nacc shell, two others had unilateral lesions and eight had sham operations (with approved protocols). Field potentials evoked by fornix stimulation were recorded in lesion electrodes to guide placements. Only the lesioned rats showed significant impairments (P<0.05) in selecting the greater reward on probe trials. However on training trials, lesioned (and sham-operated) rats made only rare errors. While the motivation to drink and the capacity for cue-guided goal-directed orientation behavior was spared, lesioned rats were impaired in learning the location of the larger reward. The accumbens lesions apparently impaired integration of position and reward value information, consistent with anatomical and electrophysiological data showing the convergence of hippocampal, amygdalar, ventral tegmental area (VTA) and prefrontal cortical inputs there.