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 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 switching over in unrestrained dogs

Conditioned switching-over was studied in unrestrained animals by means of instrumental alimentary conditioned reflexes of pressing the pedal. A complex of auditory and spatial factors (start-ground) served as conditioned alimentary signal. Backward connections were stable and were manifested in the teturning of the animal to the start-ground after feeding. It has been confirmed that the observed working readiness is a conditioned reflex of a tonic type.     

Features of differential inhibition in choice between alimentary and defensive response

Instrumental defensive (avoidance/escape) and alimentary responses (reinforced with palatable food) in dogs were conditioned by the same stimulus (6-Hz light flashes). Differential inhibition for these responses (0.6-Hz flashes) was formed in unalterable series. Later on, alternative experiments with choice between reinforcements were carried out. In both of experimental series, the degree of alimentary excitability (hunger, satiation) was changed. Numbers of responses to differential and positive conditioned stimuli and their latencies were calculated. Under condition of choice (electrodes on a leg and a pedal in front of a dog) the response depended on a dominant motivation. The dogs differed in the degree of motivation dominance. Differential inhibition was less perfect in unalterable experimental series with dominant motivation. Under conditions of choice between alimentary and defensive reinforcements, the response to the differential stimuli depended on the balance between these motivations: two days of hunger increased the number of alimentary responses, defensive responses prevailed after satiation.     

Probability analysis of elements of rat behavior after sudden and signalled interruption of food reinforcement

Probability analysis was carried out of the appearance of single elements of rats behaviour in the process of extinction of a conditioned alimentary motor reflex. The dynamics of effector behavioural components at a sudden cessation of reinforcement (usual schedule of extinction) was compared with cessation of reinforcement signalled by a previously differentiated signal and with reinforcement cessation preceded by a stimulus initially unknown to the animal. If the reinforcement cessation is signalled by a previously differentiated (negative) stimulus, in response to its action the animals "loose the aim", what is revealed in a rapid complete reduction of all elements of the goal-directed alimentary behaviour. Obviously differentiation signal actualises the memory trace of "nonreinforcement" which was formed in the previous negative experience of the animal; this is revealed in accelerated inhibition of the alimentary motor reflex under extinction.     

Changes in the cholinosensitivity of sensomotor cortex neurons during conditioned reflex extinction]

Characteristics of neuronal responses of the sensorimotor cortex to ionophoretically administered neuromediators (acetylcholine, L-glutamate) were studied in rabbit in the course of extinction of conditioned defensive reflex. In the majority of neurones the extinction of the conditioned reflex is accompanied by a drop of cholinosensitivity. In a number of neurones the extinction of reflexes either does not change the reaction to acetylcholine, or enhances it. The analysis of these reactions permits to assume the existence of a group of neurones directly involved in the formation, fixation and storage of the temporary connection.     

Electrophysiologic study of the cerebral control of swallowing

Swallowing dominant, created by serial pouring of water into rabbit's mouth cavity was tested in after-action from water supply. As a result of summation in the dominant focus of excitations elicited by stimuli of various modalities, swallowing took place. The study of swallowing dominant revealed by its stimulus which elicits its own unconditioned reflex (blinking), has shown that temporary feedback is characteristic for the dominant as well as for the conditioned reflex. Summation in the swallowing center during dominant testing by stimulation of the eye cornea takes place without conjugated inhibition of the blinking center. During discrete pouring of water into the animal's mouth, evoked potentials appear in the cortical-subcortical structures of the swallowing center. Identical potentials appear in corresponding structures before the summation swallowing. Appearance of these potentials in the electric activity of the dominant focus testifies to its readiness for summation.     

Effect of a dominant focus created in the center of the wink reflex on the local defense reflex in the rabbit

The paper deals with conjugated inhibition of rabbit's defensive limb reflex at formation of a dominant focus in the center of the eye-lid reflex. In the initial period of dominant focus formation, when the dominant comes through the stage of summation reflex, electrocutaneous limb stimulation induced, along with successive summation, temporary inhibition of the forming dominant focus. The dominant focus formed in the eye-lid center did not induce conjugated inhibition of the limb defensive reflex. In the study of the influence of the eye-lid reflex on the motor defensive one it was found that formation of temporary connection of summation reflex type, led to circulatory interaction between the centers.     

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.     

Importance of traces of a preceding unreinforced stimulus to the formation of inhibitory conditioned reflexes in the rat

The results of experiments with the inhibitory signal presented to rats after the positive one, showed the significance of the negative signal memory trace which interrupted alimentary behaviour and considerably accelerated its full extinction in response to the previously positive signal. Its significance is shown in experiments with amnesia produced by electroshock. According to the suggested concept negative conditioned reflexes are a result of formation of a temporary connection between memory traces of the negative conditioned signal and the non-reinforcement of this signal.     

EEG-correlates of alimentary behavior in rabbits with different levels of hunger and satiety]

The electrical activity of the rabbit brain at different stages of hunger and satiation was correlated with the animal's behavioral reactions. It has been found that alimentary reactions are attended with the appearance of complex high-amplitude and high-frequency electrical potentials in the lateral hypothalamic area, which increased with the longer duration of the animal's hunger, as well as during search, in response to natural and conditioned alimentary stimuli, and when feeding. As satiation sets in, they fade and disappear after food refusal. It is assumed that this form of activity is an EEG expression of alimentary motivational excitation. Its constituent rhythms reflect the different components of alimentary excitation.     

The role of trace excitatory processes in the formation of conditioned reflexes to time]

I. P. Pavlov's hypothesis on the role of trace excitation in conditioning to time was verified by mathematical methods proceeding from experimental data on elaborating in rabbits a motor alimentary conditioned reflex to a four-minute interval of time. A connection has been established between the experimental characteristics of formation of a reflex to time and some parameters of the presumed dynamics of trace excitation. The analysis helped to establish the shortest and longest intervals to which a reflex to time can be elaborated by the mechanism of trace reflex, as well as the optimal interval to which it is elaborated more easily. The experimental results so obtained are a significant corroboration to the correctness of the Pavlov hypothesis.     

The influence of systemically administered selective dopamine antagonists of D1 and D2/D3 types on alimentary and escape conditioned placing reactions in cats

Systemic administration of the specific antagonists of D1 (SCH23390, 0.005-0.1 mg/kg) and D2/D3 (raclopride, 0.1-0.25 mg/kg) dopamine receptors leeds to dose-dependent increase of the reaction time and decrease of conditined reflex probability up to full blocking (in the case of SCH23390) of alimentary and escape conditioned placing reaction in cats. The action of both antagonists was far more suppressive regarding conditioned escape reflex. The action of SCH23390 was far more effective than that of raclopride concerning both types of conditioned reflexes.     

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.     

Tonic component of the conditioned reflex process and its functional role

Tonic background activity of 266 neurones in the hippocampus and different neocortical areas was studied in freely moving rabbits in the process of defensive and food instrumental conditioned performance and during switching-over of instrumental and classical food and defensive reflexes. Associations of CS and reinforcement evoke background activity changes in most of recorded cortical neurones preceding the development of other conditioned manifestations. Conditioned reflex was performed only after reaching the background firing rate of almost every examined neurone optimal for its realization. The performance of different conditioned reflexes was associated with different background activity levels of cortical neurones. The above mentioned data form the experimental basis for the identification of the tonic component in conditioned process which reflects tonic character of temporary connection formation and function.     

Neurophysiologic analysis of the critical period of delay of a reinforcing stimulus in the dog

At interval of less than 100 ms between indifferent sound and unconditioned electrocutaneous stimulation, classical defensive conditioned reflex is not elaborated in dogs, in full correspondence with literature data. But intracortical temporary connection is established; this fact is shown by electrographic phenomena, the most specific and demonstrative among them is "conditioned evoked potential". The absence of behavioural (peripheral) and presence of electrographic (central) manifestations allow to assume that for the formation of the conditioned reflex of full value the involvement is necessary of additional activational (motivational) mechanisms, connected with reticular and (or) limbic subcortical structures which do not react to the conditioned stimulus at time deficit in conditions of microdelay.     

Emotional stress during conditioned reflex transformation of heterogeneous instrumental reflexes

The factors leading to pronounced emotional stress accompanied by changes in electrical activity of hippocampus were studied in four dogs during elaboration of conditioned switching-over of heterogeneous instrumental reflexes. Objectively recorded signs of emotional stress were observed in two cases: when the animal was not accurate enough in discerning defensive and alimentary situations and throughout the improvement of instrumental defensive reflex. Pronouncement of hippocampal theta-rhythm increased at those stages of switching-over elaboration where the probability of successful avoiding pain stimulation was relatively low. The data obtained permit the conclussion that theta-rhythm is the correlate of the degree of the emotional stress and not only a manifestation of general arousal reaction depending on the level of sensory input.     

The role of the lateral and medial hypothalamus in reproducing a motor reaction as the signal during the acquisition of classical conditioned reflexes]

In experiments on three dogs there was shown that testing electrostimulation of the lateral hypothalamus reproduced the motor reaction which is a signal stimulus at elaboration of classic alimentary conditioned reflexes (CRs) and did not reproduce it at elaboration of classic defensive CR. Testing electrostimulation of medial parts of the hypothalamus reproduced, as LH electrostimulation the "signal" motor reaction, but in less percentage of cases, during elaboration of classic alimentary CRs and did not reproduce it at elaboration of classic defensive CRs. The reproduction of the signal motor reaction at LH electrostimulation is connected with activation of backward conditioned connection from motivation structures of the hypothalamus to representation of the signal stimulus in the motor cortex.     

Transformation of conditioned responses of the tonic type

A reversal of signal meaning of stimuli signalling experimental situation was performed on dogs with conditioned defensive motor reflexes to clicks: clicks and electro-cutaneous stimulation were stopped, and the animals were started to be given food in the same experimental situation. Reversal of conditioned defensive tonic stimuli to alimentary ones led to a complex of behavioral and electrographic reactions. Isolated click tests showed that signals of experimental situation considerably affect a fully-elaborated defensive motor reflex. At the same time the preparatory role of certain situational elements may be specialized with regard to the components of the conditioned reflex, in particular to the local flexor reaction.     

Conjugate inhibition in the presence of an eyelid reflex dominant in the rabbit

Conjugated inhibition was studied of the swallowing reflex during formation of dominant focus in the centre of the eye-lid reflex. In the initial period of the dominant focus formation when the dominant passed through the stage of summating reflex, the swallowing reflex was not inhibited. When the dominant turned to optimal stage, i. e. when it was reinforced by stimuli of various modalities, the swallowing reflex was conjugately inhibited. When the dominant turned to pessimal state, summation was not observed in the dominant focus, and conjugated inhibition went on. In the study of the influence of the eye-lid reflex on the swallowing one, it was found that during formation of temporary connection of the type of summating reflex a circular interaction between the centres took place.