[Study of extracellular concentration of dopamine and its metabolites in mice striatum by a microdialysis technique at intraperitoneal administration of MPTP].

In this paper a structure of a microdialytic cannula inserted into brain areas just before a microdialysis is described. The cannula used allowed to find out a correspondence of behavioral and biochemical changes in C57BL/6 mice at various time intervals after a single dose administration (20 mg/kg) of the neurotoxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, without any additional pharmacological actions enhancing an extracellular striatal dopamine concentration. Immediately after 1-methyl-4-phenyl-1.2,3.6-tetrahydropyridine administration an essential disturbance of mice behavior and a significant reduction of the extracellular concentration of dopamine and homovanillic acid were observed in striatum. A week after the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration neither behavior nor the extracellular dopamine and homovanillic acid striatal concentration substantially differed from those of controls. 30 days after the neurotoxin administration there was again an essential disturbance of behavior and the large reduction of dopamine and its metabolite concentration in striatum. There was suggested that a reduction of the dopamine concentration immediately after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine injection connected with abnormalities of dopamine synthesis and metabolism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine whereas a reduction of the extracellular striatal dopamine concentration 30 days after 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine administration related to damage of the nigrastriatal dopaminergic system.

Neuron activity in the anterolateral motor cortex in operant food-acquiring and alcohol-acquiring behavior.

The interactions of the neuronal mechanisms of food-acquiring behavior and newly formed operant alcohol-acquiring behavior were studied by recording the activity of individual neurons in the anterolateral area of the motor cortex in chronically alcoholized rabbits. Adult animals learned food-acquiring behavior in a cage with two feeders and two pedals, in the comers (the food in the feeders was presented after pressing the corresponding pedal). After nine months of chronic alcoholization, the same rabbits learned an alcohol-acquiring behavior in the same experimental cage (gelatin capsules filled with 15% ethanol solution were placed in the feeders instead of food). Analysis of neuron activity showed that the set of neurons involved in supporting food-acquiring and alcohol-acquiring behaviors overlapped, though not completely. These experiments not only help us understand the neuronal mechanisms of the newly formed and the previously formed behaviors, but also facilitate the development of concepts of the similarity of the neuronal mechanisms of long-term memory and long-term modifications of the nervous system, occurring in conditions of repeated intake of addictive substances.

[Activity of neurons in the anterolateral region of the rabbit motor cortex during taking food and nonfood objects in instrumental behavior]. / Aktivnost' neironov anterolateral'noi oblasti motornoi kory mozga krolika pri zakhvate pishchevykh i nepishchevykh ob''ektov v instrumental'nom povedenii.

We showed earlier that only 2-4% of N-neurons in the rabbit's anterolateral ("masticatory") motor cortex (AC) that are being specialized in relation to Newly formed acts (such as pressing the pedal, approaching the pedal) during the elaboration of instrumental food-acquistion behavior. The majority of neurons in this area are O-neurons that are specialized in relation to the Older acts formed long before the acquisition of instrumental behavior: mostly taking of food. It was shown also that electrical stimulation of this area produced jaw movements. It might seem reasonable to propose that the number of N-neurons may be increased in this area if pedal pressing in substituted with instrumental act like seizure and pulling a ring that is more corresponding to the "projectional property" of the AC. Here we show that the number of N-neurons in rabbit's AC remains constant -3.4%, even is the animals that were trained to pull a ring instead of pressing a pedal. Thus, we assume that the small number of N-neurons is the stable property of the AC. However, the role of the AC in the subserving of the behavior does not remain the same. Much more AC units (O-neurons) were activated in the ring pulling than in the pedal pressing instrumental act.

[Activity of anterolateral motor cortex neurons in instumental food-acquisition and alcohol-acquisition behavior]. / Aktivnost' neironov anterolateral'noi motornoi kory v instrumental'nom pishchedobyvatel'nom i alkogoledobyvatel'nom povedenii.

Singleunit activity of anterolateral area of motor cortex in rabbits subjected to chronic ethanol treatment was recorded to study interconnections of neuronal mechanisms of newly formed instrumental alcohol-acquisition behavior (IAB) and previously formed food-acquisition behavior (IFB). Adult animals were trained to perform IFB in experimental cage equipped with two food boxes and two pedals situated in the corners of the cage. Food was presented automatically in a food box after the pressing of an appropriate pedal. Same rabbits after 9 mo. of chronic alcohol treatment were trained to perform IAB in the same experimental cage (gelatin capsules filled with 15% ethanol solution were placed into the food box instead of food). Activity of 121 units of anterolateral area of motor cortex was studied. Each unit discharges were analysed in IAB as well as in IFB. The data obtained testifies that neuronal sets subserving IAB and IFB overlap but not completely. 44 "common" neurons permanently activated in both behaviors and 3 neurons specifically activated in each of behaviors (one in IAB and two in IFB) were found. We consider the formation of IAB as systemogenesis that is related to the consolidation processes: the formation of new neuronal specializations and to the accommodative re-consolidation: modification of early specialized cells ("common"). It is shown in the Discussion that present experiments help us not only understand interconnections of neuronal mechanisms of newly formed IAB and early formed IFB but also provide an additional insight into the nature of similarity between neuronal mechanisms of long-term memory and long-lived modifications resulting from repeated drug exposure.

How moving visual stimuli modulate the activity of the substantia nigra pars reticulata.

The orientation of spatial attention via saccades is modulated by a pathway from the substantia nigra pars reticularis (SNr) to the superior colliculus, which enhances the ability to respond to novel stimuli. However, the algorithm whereby the SNr translates visual input to saccade-related information is still unknown. We recorded extracellular single-unit responses of 343 SNr cells to visual stimuli in anesthetized cats. Depending on the size, velocity and direction of the visual stimulus, SNr neurons responded by either increasing or decreasing their firing rate. Using artificial neuronal networks, visual SNr neurons could be classified into distinct groups. Some of the units showed a clear preference for one specific combination of direction and velocity (simple neurons), while other SNr neurons were sensitive to the direction (direction-tuned neurons) or the velocity (velocity-tuned neurons) of the movement. Furthermore, a subset of SNr neurons exhibited a narrow inhibitory/excitatory domain in the velocity/direction plane with an opposing surround (concentric neurons). According to our results, spatiotemporally represented visual information may determine the discharge pattern of the SNr. We suggest that the SNr utilizes spatiotemporal properties of the visual information to generate vector-based commands, which could modulate the activity of the superior colliculus and enhance or inhibit the reflexive initiation of complex and accurate saccades.

A subset of cingulate cortical neurones is specifically activated during alcohol-acquisition behaviour.

UNLABELLED: A new need is associated with the formation of behaviour directed at its satisfaction. In chronically ethanol-treated rabbits a bodily need develops to acquire and consume alcohol. The present study examined the firing properties of single neurones in the cingulate (limbic) cortex of chronically ethanol-treated rabbits. The main questions of this study were: are there neurones in the cingulate cortex which specifically increase their firing during alcohol-acquisition behaviour (AAB)? What is the relationship between the neuronal mechanisms of pre-existing and newly formed behaviour? Adult rabbits were taught to acquire food by pressing pedals. After 9 months of ethanol treatment, the same rabbits were taught to acquire ethanol (15% solution in a 0.5-mL capsule) by means of the same instrumental METHOD: Activity of the 118 neurones was recorded from the cingulate cortex. The comparison of activity of each neurone in AAB and food-acquisition behaviour (FAB) enabled us to reveal that their subservings overleap substantially but not completely: 41% of 'common neurones' involved in the subserving of both FAB and AAB as well as 5% of 'alcohol-neurones' (alcohol-acquisition specific cells) were found. We think of the latter neurones as units that were specialized during the forming of alcohol-seeking behaviour. Thus, present experiments help us not only to answer the above questions but also to provide an additional insight into the nature of similarity between neuronal mechanisms of long-term memory and long-lived modifications resulting from repeated drug exposure.