Features of the formation of conditioned secretory reflexes in response to the stimulation of different areas of the caudate nucleus of the dog

Properties were studied of elaboration of conditioned alimentary secretory reflexes to threshold electric stimulation of the caudate nucleus in dogs. The rate of formation of such a reflex and its magnitude were considerably lower than in reflexes elaborated to distant stimuli. Latencies were longer; dynamics of conditioned and unconditioned secretory reactions was similar to that of reflexes to a weak stimulus--light. The motor component of the conditioned alimentary reaction, as a rule, was absent. Characteristics were revealed of formation of alimentary reflexes to stimulation of the dorsal and ventral parts of the head and body of the caudate nucleus.     

Effect of activation and blockade of the GABA-ergic system of the substantia nigra in the midbrain on the realization of conditioned food reflexes in dogs

Bilateral injection of 45 mcg of GABA into substantia nigra pars compacta produced in dogs a manifested improvement of parameters of the conditioned differentiation inhibition but failed to influence the positive Pavlovian alimentary conditioned reflex. Injection of GABA synaptic antagonist--picrotoxin impaired conditioned alimentary behaviour. Numerous injections of the GABAergic pharmacological agents resulted in motor disturbance--rotatory movements--and skin trophic deviations. The data obtained and literature references give ground for discussion of the role of striato-nigral and internal GABAergic substantia nigra systems in the positive modulation of adaptive alimentary behaviour and conditioned stimuli differentiation.     

Dynamics of the spectral composition of the hippocampal theta-rhythm in the dog during switching-over of heterogeneous instrumental reflexes

In two dogs with electrodes chronically implanted in the hippocampus, hippocampal electrical activity and the heart rate were recorded in the process of elaboration of a conditioned switch-over of operant alimentary and defensive responses. Averaged computerized spectral characteristics of hippocampal theta-rhythm were essentially different between the alimentary and defensive situations in intersignal period as well as during the action of triggering conditioned stimulus. Individual differences in the dominant frequency of bioelectrical activity were observed. The animal with a higher theta-rhythm frequency elaborated conditioned switch-over of heterogeneous operant responses sooner and more successfully.     

Effect of successive lesions of the hippocampus and amygdaloid body on conditioned-reflex alimentary reactions in rabbits

Bilateral electrolytic lesions of the dorsal hippocamp and basolateral amygdalar complex impede the differential and extinctive inhibition. The damage of the corticomedial amygdala against a background of the dorsal hippocamp deficiency facilitates differentiation and extinction of alimentary reflexes induced by a decrease of the alimentary motivation and by weakening of alimentary conditioned reflexes. Lesions of the dorsal hippocamp after the corticomedial amygdala damage facilitates the training of positive alimentary reflexes, but weakens inhibitory conditioned reflexes.     

The possibility of elaborating conditioned reflexes on the basis of emotional reactions evoked by electrical stimulation of limbic structures]

In experiments on cats with chronically implanted electrodes a conditioned stimulus (200 c/s tone) was paired with electrical stimulation of limbic structures, which produces pronounced emotional behaviour: defensive, aggressive, alimentary or drinking reactions. It has been shown that conditioned reactions are not elaborated on the basis of electrical stimulation, which activates alimentary, drinking or aggressive behaviour. Neither is a conditioned reflex formed to the combination of sound and stimulation of the brain structures, which inhibits alimentary behaviour. A distinct conditioned fear reaction sets in as a result of combination of sound and electrical stimulation of brain structures, which evoke defensive behaviour. The data obtained are analyzed in the light of the significance of natural requirements of the organism for the elaboration of conditioned reflexes.     

Conditioned reflex and electrical activities of the hippocampus during the random use of heterogeneous triggering stimuli

In dogs with electrodes chronically implanted in the hippocampus, the conditioned activity, heart rate frequency and spectral characteristics of the hippocampal theta-rhythm were studied in conditions of irregular presentation after a preparatory stimulus now of alimentary and now of defensive triggering conditioned stimuli. It is shown that uncertainty of alimentary or defensive reinforcement is a stronger emotiogenic factor than the action of the triggering defensive conditioned stimulus. Changes in electrical hippocampal activity and autonomous activity depend, along with other factors, on forecasted volume of the forthcoming motor activity. The speed of instrumental conditioned reflexes formation correlates with the hippocampal theta-rhythm frequency, typical for the given animal.     

Fluorescence of dopaminergic terminals during elaboration of alimentary conditioned reflexes in the cat

A decrease of intensity of fluorescence of dopaminergic terminals in the nigrostriate and mesolimbic systems of rats was revealed under alimentary deprivation and during conditioned alimentary reaction. This decrease detected against the background of catecholamines synthesis blockade (alpha-methyl-para-thyrosine 40 and 80 mg/kg intraperitoneally) testifies to an activation of dopaminergic terminals and participation of nigrostriate and mesolimbic systems in conditioned alimentary reaction.     

The role of the lateral and medial hypothalamus in reproducing food and escape instrumental reactions]

In experiments on two dogs it has been found that testing electric stimulation of the lateral hypothalamus reproduces instrumental movement in case of elaborated alimentary instrumental conditioned reflexes (CR) to a tone and does not reproduce it at elaborated acid-defensive instrumental CR. Under testing electric stimulation of the medial hypothalamus the instrumental movement practically is not reproduced neither in alimentary nor in defensive situation. Appearance of instrumental movement at LH electro-stimulation in alimentary situation is connected with activation of backward conditioned connection from motivation "alimentary" LH centre to representation of this movement in the motor cortex.     

Effect of neurotizing exposures on conditioned reflex activity in the late postresuscitation period in rats

In white rats resuscitated after 10-minutes stop of the blood circulation, conditioned switching over was elaborated on the basis of alimentary and defensive instrumental reflexes and the effect was studied of neurotizing influences. Single application of electrocutaneous pain stimulus in alimentary situation ("collision") led to more expressed disturbances of conditioned activity in resuscitated rats than in intact ones. Differentiation of a signal different from the positive conditioned stimulus only by the height of the tone, was practically not elaborated in resuscitated rats, and the disturbance of the conditioned alimentary reflex to the reinforced signal appearing during differentiation elaboration, was manifest in them to a greater degree. The obtained data testify that even a short-time brain ischemia, accompanied by a fast and full restoration of the neurological status, leads to functional defects of the CNS appearing at subsequent neurotic influences.     

The characteristics of a change in the congenital and acquired forms of behavior in rats with genetic catalepsy

In two groups of rats--outbred control rats and GC line ones the behaviour in the open field was studied, as well as alimentary situational instrumental conditioned reflex was elaborated. Rats of GC line were less mobile in the open field as compared with the control ones; their investigating reflex was low; several parameters showed a higher level of agitation and fear. Handling of rats of GC line improves these behavioural parameters and brings them closer to the norm. Elaboration of alimentary situational conditioned reflex in rats of GC line is delayed as compared with the control ones. Passive-defensive reflex expressed in the form of cataleptic stupor, is of dominant character and significantly prevails over cognitive and alimentary reflexes.     

The influence of electrocoagulation of the septum and section of the entorhinal cortex on general behaviour and memory in cats

In chronic experiments on cats it was shown that the lesion of the medial part of the septum does not result in the "septal syndrome"; the ratio of the different sleep-wakefulness cycle phases remains within the baseline values; the acquisition, retrieval and extinction of instrumental alimentary conditioned reflexes proceed normally; the delayed conditioned reflexes are impaired. Massive septal lesion, including its lateral part, leads to the development of the "septal syndrome"; there are changes in the structure and percentage of the different sleep-wakefulness cycle phases; the acquisition and extinction of instrumental alimentary reflexes with the sound discrimination are markedly retarded; the performance of delayed conditioned reflexes is completely destroyed. The section of the entorhinal cortex produces an increase in the number of repeated errors and perseverative movements during performance of instrumental alimentary reflexes, the deceleration of the acquisition and extinction of instrumental alimentary reflexes, complete disturbance of the delayed conditioned reflexes and does not affect the sleep-wakefulness cycle. The problems of the role of the hippocampus and its main inputs in the regulation of the short-term operative memory in the "pure form" as well as the significance of the descending influence of the hippocampus on the regulation of general animal behavior were also discussed.     

Conditioned reflex activity of pigeons as affected by an infra-low frequency alternating magnetic field

In experiments on 35 pigeons formation and realization was studied of alimentary motor conditioned reflexes under the influence of alternating magnetic field (AMF) with a frequency of 5 and 8 Hz and induction 5100 nTl. It has been found that under the action of such AMF, the percent of adequate responses lowers and the time of motor reaction during execution of motor alimentary conditioned reflexes and of delayed reactions increases. Realization of delayed reactions is disturbed more significantly than that of the present conditioned reflexes. AMF with a frequency of 8 Hz influences more expressively the pigeons conditioned activity in comparison with 5 Hz frequency.     

A comparison of the effects of single and chronic microinjections of GABA and picrotoxin into the caudate nucleus on the conditioned reflexes of dogs

The effects on Pavlovian alimentary conditioned reflexes realization of two methods of intrastriatal microinjections--acute (separate) and long-term (chronic) one--are compared in experiments on dogs. Bilateral acute administration and the first week of chronic injection of 45 mcg of GABA into the caudate nuclei produced in dogs a manifest improvement of parameters of the conditioned differentiation inhibition, but only in the next period of chronic treatment an improvement of the positive Pavlovian alimentary conditioned reflex was obtained. The both ways of picrotoxin treatment impaired conditioned behaviour, and this effect was observed after the end of injection. No withdrawal effects were recorded. The data obtained give ground for discussion of the role of striatal GABAergic system in the positive modulation of adaptive alimentary behaviour. The application of novel psychopharmacological method in experimental and clinical fields of investigation is discussed.     

Relation between the level of conditioned reflex activity and concentration of serotonin in the blood of normal and neurotic dogs

Higher nervous activity of dogs was studied using Pavlovian method of alimentary salivary conditioned reflexes. Serotonin (5- hydroxytryptamine) content in the venous blood was defined by means of fluorescent spectrofluorimeter using orthophthalic dialdehyde. A high level of conditioned and unconditioned reflexes was accompanied by a low serotonin blood content, while a low level of reflexes was accompanied by a high serotonin content. Negative correlation is supposed to exist between the degree of activation of nervous processes and blood serotonin content. Blood serotonin content increased in dogs in experimental neurosis with expressed reduction of the level on alimentary conditioned and unconditioned reflexes.     

Inhibitory effect of the amygdala on alimentary-conditioned reflexes in the dog

In experiments on dogs, changes of conditioned alimentary reflexes were studied under stimulation (50-100 mcA, 1, 40, 100 imp/s, 0.5 ms) of the basolateral area of amygdala before and after electrolytic ablation (5 mA, 60 s) of the head of the caudate nucleus. Stimulation of the amygdala, which elicited inhibition of conditioned secretory reflexes and prolongation of latencies in intact dogs leads to opposite - activating - influences after destruction of the caudate nucleus head. A conclusion is made on the participation of neurophysiological and neurochemical mechanisms of the caudate nucleus in transmission of inhibitory effects of the amygdala on alimentary conditioned reflexes.     

The effect of lesions of the dorsomedial thalamic nucleus on alimentary conditioned reflexes and food intake in dogs.

The experiments have been carried out on 6 dogs with type II conditioned alimentary reaction. After achieving the criterion in all animals the dorsomedial thalamic nucleus was destroyed by means of electrocoagulation. After the operation hypophagia developed with a rise in the number of intertrial responses and disinhibition of the alimentary conditioned reaction not exceeding 6 days. The obtained results confirm in part the hypothesis of Brutkowski who regarded this nucleus as belonging to a system controlling feeding behavior.     

The effects of intracerebral injections of kynurenine on conditioned reflex activity and on the serotonin level of the blood in dogs]

Higher nervous activity of dogs was studied by classical Pavlovian method of alimentary salivary conditioned reflexes and serotonin content in blood was measured. Kynurenine sulfate in a dose of 300 + 300 mkg (bilaterally) was injected in the dorsal hippocampus region through chemiotrodes. In most cases the injection of the substance led to changes towards excitation (increase of conditioned and unconditioned alimentary salivation in the day of injection and the next day) and also to a rise of serotonin content in animals blood.     

An EEG-study of participation by the head of the dog caudate nucleus in alimentary conditioned reflex activity]

It was shown during alimentary conditioning in dogs that in the "background" electrocaudatogram there are rhythms typical of the act of eating, which become more clearly pronounced under the action of the conditioned stimulus. The EEG of the caudate nucleus head sharply changed during discordance reactions. It has been assumed that the caudate nucleus head forms a link in the functional system of the alimentary conditioned reflex at stages of afferent synthesis and functioning of the action acceptor.     

Functional differentiation of the theta-rhythm of the hippocampus in the cat

On the model of discriminating alimentary conditioned reflex with spatial separation of the sources of conditioned (CR, light flashes) and unconditioned (feeding trough) stimuli the theta-rhythm of the dorsal hippocampus was evaluated in cats. Two types of the theta-rhythm were observed in the spectrum of the hippocampal electrical activity: low-amplitude, consisting of a slow growing theta-waves (type I) and high-amplitude consisting of rapidly increasing theta-waves (type II). The type I theta-rhythm is sensitive to noradrenaline and correlates with behavioural forms directed immediately to the realization of alimentary motivation, while the type II is sensitive to serotonin and correlates with behavioural forms directed to the source of the conditioned stimulus. Enhancement of the type II theta-rhythm takes place during a delay of the expected conditioned stimulus. It is suggested that type I theta-rhythm reflects a level of activity of the brain structures connected with unconditioned mechanisms, with realization of biological motivations, while type II theta-rhythm is connected with conditioned reinforcing stimuli; it correlates with various forms of conditioned orienting reflexes and reflects the work of the "nervous model of reinforcing stimulus".     

Alimentary conditioned reflexes in the dog after pharmacologic activation and blockade of dopaminergic structures of the caudate nucleus

Bilateral injections of 60 mcg of amphetamine and dopamine into the head of caudate nucleus produced in dogs a manifested impairment of parameters of Pavlovian alimentary conditioned reflexes but did not influence the conditioned differential inhibition. Injections of 10 mcg of haloperidol were ineffective. The most effective were the influences on the dorsal part of the caudate nucleus head.