Influence of emotional stimuli on behavior and respiration of rabbits with various locomotor activity in the "open field"

Different behavioral reactivity of rabbit groups differentiated by locomotor activity in the "open field" was revealed during exposure to emotional stimuli (rustle, loud sound, pressuring on back of the neck, vibroacoustic tactile stimulation of an ear). In passive rabbits, the active locomotor reactions were induced harder and freezing was obtained easier than in active animals. During exposure to sound stimuli, passive rabbits increased their locomotion more rarely than active animals, pressing on back of the neck produced longer freezing, a threshold of defensive ear shaking in response to a vibroacoustic stimulus in passive animals was highest. Training to mild immobilization increased the threshold of defensive responses in active rabbits and animals of the intermediate type. Changes in respiratory parameters were correlated with behavioral reactions to emotional stimuli. The duration of exhalation and respiratory cycle increased during freezing and increased during enhanced locomotion. The duration of inhalation decreased in response to emotional stimuli irrespective of a behavioral reaction. The respiratory reactions to emotional stimuli differed in rabbits of different groups. The respiratory rate more frequently changed in passive rabbits than in animals of other groups. Passive animals reacted mainly by exhalation, active rabbits and animals from the intermediate group predominantly responded by inhalation.     

Changes in the level of oxygen tension in different brain structures of rats in positive and negative emotional states

Changes of oxygen tension (pO2) level in various brain structures were studied in rats in positive and negative emotional states. It is established that pO2 level changes depend on the character of behavioural reactions: "active" type of behaviour (emotionally positive orienting-investigatory, actively defensive) is accompanied by pO2 level increase, and "passive" type of behaviour ("freezing" reaction)--by a decrease of pO2 level. Changes of oxidative brain metabolism observed at "active" and "passive" types of behaviour indicate, respectively, adaptive and nonadaptive character of these behavioural reactions.     

Dependence of behavioral responses form during shake-off conditional reflex on laterality of the neocortex

Pattern of discharges and interhemispheric interaction of parietal neurons (somatosensory presentation of the ear) were compared in interstimulus intervals before active shake-off and passive freezing reactions at stimuli after elaboration defensive avoid reflex. Before passive reactions in contrast to active right-side influences on left-side neurons were reinforced with delay to 100 ms, it result in appearence of asymmetry in interhemispheric interaction with right-side dominance. Before passive reactions intensity of delta-frequencies was increased in impulsation of single neurons and in interaction of cells pair. On this evidence the pattern of interhemispheric asymmetry before stimuli can be one of a number of factors, determinant active or passive form of behavioral reactions and also reflective of activation level of neocortex.     

Effect of GABA receptor agonist phenibut on behavior and respiration of rabbits in the negative emotional situation

The influence of systemic injection of GABA-receptor agonist--phenibut (40 mg/kg, s/c) on open field behavior, behavioral reactivity and changes in respiratory parameters after exposure of negative emotional stimuli was studied in three rabbit groups differentiated by locomotor activity in open field (active, passive and medium-active animals). The injection of phenibut results in decrease of rabbits horizontal locomotor activity and some components of research behavior in open field and also decrease of behavioral reactivity on emotional stimuli. At the same time the probability of both an active orienting exploratory or defensive reactions and passive reactions (freezing) were decreased. The influence of phenibut depended on typological features of rabbits: the most potent effect occurred upon behavior of active rabbits, less on passive animals and practically none on medium-active rabbits. The phenibut injection results in increase of duration of inhalation during exposure to emotional stimuli, whereas it decreased in normal.     

Comparative characteristics of psychoemotional patterns in Albino and Wistar rats

Analysis of psychoemotional behavioral component in Albino and Wistar rats during solving a cognitive task showed that intra-population differences were determined by the relationship between passive and active forms of unconditioned reactions. Quick-learning rats from both populations were characterized by the dominance of active forms of psychoemotional reactions over the course of training. The learning process in slow-learning rats was accompanied mainly by passive emotional manifestations, whereas active reactions dominated at the stage of habit realization. Passive forms of manifestations prevailed over active forms over the course of training in both Albino and Wistar rats which failed to solve the task. The interpopulational psychoemotional differences were quantitative and depended only on the learning styles. Wistar strain was characterized by a decreased percent of animals which were able to solve a cognitive task (40% versus 80% in Albino rats), affective flatness and decreased tolerance to information loadings.     

Changes in the oxygen tension level in different brain structures of rats in the waking-sleep cycle

Changes of oxygen tension level (pO2) in the visual cortex, dorsal hippocampus, lateral hypothalamus and central grey substance were studied during wake-sleep cycle in rats. The dependence was established of pO2 level changes on the character of behavioural reactions and on the accompanying hippocampal EEG activity: during orienting-investigatory and active defensive behaviour and also during paradoxical sleep, accompanied by hippocampal theta rhythm, pO2 level increased; during passive-defensive behaviour "freezing" reaction accompanied by desynchronization of the hippocampal rhythmic, the level of pO2 decreased. The obtained data confirm Routtenberg hypothesis about two relatively independent systems of ascending activation with different types of hippocampal EEG activity and supplement it with a thesis that the activity of these systems is accompanied by different shifts of brain oxidative metabolism.     

Individual propensity to active or passive behavior during exposure to emotional stress in individuals with various blood cortisol levels

Effects of baseline and reactive blood cortisol on operator's performance were studied in subjects with active of passive behavioral reactions under exposure to stress. The type of behavioral reaction to stress (shift in the rates of omissions or false alarms) was found to be associated with the baseline blood cortisol and its levels averaged in the course of the experiment. Subjects with active reaction (stress produces an increase in the rate of errors of the false-alarm type) were characterized by the low cortisol level, whereas its high level was observed in subjects with passive reaction (stress produces an increase in the rate of errors of the omission type). Individuals with high baseline cortisol level and those with the passive reaction to stress exhibited enhanced cardiovascular reactivity during performance in normal conditions and its reduction during the performance under exposure to stress.     

Domestication-related behavior as a factor for the long-term adaptation of the sheep hypothalamic-pituitary-adrenocortical system to social isolation

The reaction of the hypothalamic-pituitary-adrenocortical axis (HPA) to social isolation from the herd was studied in 45 ewes of the Altaian breed at the age of 12, 16, and 27 months. The animals belonged to either "wild" or "domesticated" phenotypes which contrasted in the character of feeding and defensive responses to a human. The basal corticoid level in animals of both behavioral phenotypes was similar. The corticosteroid reaction was absent in animals with the "domesticated" type of behavior, while it was significantly pronounced in animals with a clear-cut behavioral reaction of withdrawal from a human ("wild" phenotype) at different ages. Sheep of the "wild" type of behavior were not uniform in the rate of the age-dependent decrease in withdrawal and stress reactions: these reactions were stable in individuals of "conservative" phenotypes. Thus, the ontogenetic formation of the long-term adaptation of the HPA axis of sheep to isolation depends on genetically determined behavior and factors, which control correlated changes in feeding and defensive reactions in animals of the "wild" phenotype.     

Interhemispheric asymmetry of neocortex and hippocampus in orienting exploratory behavior of rabbits

Correlation of discharges of cortical neurons in symmetrical points of the visual and parietal cortices and left and right hippocampal CA1 neurons was studied in freely moving rabbits during exposure to emotional stimuli. Crosscorrelation histograms were plotted. As compared to the initial state, during an active orienting exploratory reaction to stimuli, the left-side influence on right-hemispheric cortical neurons with a delay about 100 ms increased, which led to asymmetry in interhemispheric interaction with the left-side dominance. During freezing, the left-side influence became weaker, and the effects of the right hemisphere prevailed. Hippocampal asymmetry in neuronal activity was in reciprocal relationship with neocortical asymmetry. In the hippocampus, the right-side influence with a delay about 200 ms increased during the active exploratory reactions resulting in the right-side dominance. Freezing was accompanied by strengthening of the left-side influence (the left-side dominance). During the active locomotion, neuronal interaction in the hippocampus was predominantly realized in the theta-range frequency, whereas freezing was characterized by the delta-range correlation. It was concluded that the active or passive nature of a behavioral reaction to emotional stimuli was correlated with changes in asymmetry in the interhemispheric neuronal interactions at the cortical and hippocampal levels.     

Seeing what the mouse sees with its vibrissae: a matter of behavioral state

The behavioral state of an animal is accompanied by ongoing brain activity that primes neuronal circuitry to sensory inputs. While it should come as no surprise that the pattern of cortical activation is tied to behavioral states, only now has this dependence been imaged. In this issue of Neuron, Ferezou, Bolea, and Petersen show that the level and spatial extent of activation of vibrissa sensory cortex critically depend on behavioral context and mode of stimulation, i.e., passive versus active contact.     

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.     

Domesticated behavior in sheep. Role of behavioral polymorphism in the regulation of stress reactions in sheep]

The relationship between behavioral polymorphism and the variation for the function of the hypothalamic-pituitary-adrenocortical axis (HPAA) was studied in the meat-and-wool (n = 447) and Altaian fine-fleece (n = 45) sheep breeds under production farm conditions. The behavior studied included negatively associated reactions: feeding reactions and defensive reactions in relation to human. In sheep, the intrapopulation variation for the stress level of corticosteroids depended on the effect of behavior, the type of stimulus, and the interaction between these two factors and correlated with the behavior phenotype (r varied from -0.551 to -0.226). In the stress responses to either 24-h starvation or lamb weaning, hormonal reactions were similar in wild-type sheep that have clearly marked defensive reactions and in the sheep of the domestic phenotype that was contrasted to the wild type. In the stress responses to isolation from the herd, transportation, and competition for food, hormonal reactions were stronger in the wild type than in the domestic phenotype; alternatively, in the stress response to being kept in cages in pairs, hormonal reaction was stronger in the domestic phenotype than in the wild type. In the sheep that were placed in cages, a single playing of tape-recorded anxiety signals caused the motivational or emotional stress that was characterized by an unusually long latent period of the progressive HPAA reaction and its subsequent chronic course (up to 9 days). Animals of contrasted behavioral phenotypes differed in the course of the HPAA reaction. Heritable behavioral polymorphism and interaction between behavior and the type of stimulus are the regulation factors in the expression and variability of stimulus-specific reactions of HPAA. Behavior can serve as the genetic marker for individual features of HPAA functioning in the stress response of sheep.     

The role of brain serotonin in the expression of genetically determined defensive behavior

The review summarizes the results of long-term studies on the role of the brain mediator serotonin and genetic predisposition to various types of defensive behavior. The involvement of the serotonergic brain system in the mechanisms of genetic control of both active and passive defensive responses has been established using silver foxes, Norway rats of S40 selection for low and high aggressiveness to humans, aggressive mice with genetic knockout of monoaminoxidase A, and S40 rats selected for predisposition to passive defensive response of freezing (catalepsy). The changes in the serotonergic 5-HT1A-brain receptors of rats genetically predisposed to different strategies of defensive behavior were similar. However, the activity of the key enzyme of serotonin biosynthesis and the brain structures, in which serotonin metabolism was altered, significantly differed with regard to the preferred strategy. The conclusion was drawn that the 5-HT1A-receptors and enzymes of serotonin metabolism in the brain are involved in implementing genetic control of defensive behavior. Expression of the 5-HT1A-brain receptors was suggested to determine the levels of fear and anxiety and, consequently, the predisposition to defensive behavior, whereas the preferred strategy of defensive response (active or passive defensive) depends on genetically determined features of serotonin metabolism in the brain structures.     

Defensive Aggregation (Huddling) in Rattus Norvegicus toward Predator Odor: Individual Differences,Social Buffering Effects and Neural Correlates

Aggregation is a defensive strategy employed by many prey species in response to predatory threat. Our group has characterized defensive aggregation (huddling) in Rattus norvegicus in response to a ball of cat fur. In this situation some rats huddle less, and approach the threatening cue more than others (active vs. passive responders). The present study explored whether active responding is a stable phenotype associated with behaviors outside direct predatory encounters. The neural substrates of active and passive responding under predatory threat were explored using c-Fos immunohistochemistry. Finally, we examined whether the presence of conspecifics during predatory threat biases behavior towards active responding. Active and passive responding styles were found to be stable in individual rats across consecutive group exposures to cat fur, and were predicted by anxiety-like behavior in an open-field emergence test. Active responders displayed less conditioned fear in an environment associated with predatory threat, and had higher post-exposure intake of a weak sucrose solution (a test of “anhedonia”). Active responding was associated with: greater cat fur-induced activation of the accessory olfactory bulb, reflecting greater olfactory stimulation in rats actively approaching the fur; lowered activation of somatosensory cortex, reflecting reduced huddling with conspecifics; and reduced activation in the lateral septum. Social exposure to cat fur promoted active responding relative to individual exposure, and lowered c-Fos expression in the dorsomedial periaqueductal grey, medial caudate putamen and lateral habenula. We conclude that individual differences in anti-predator behavior appear stable traits with active responders having a more resilient phenotype. Social exposure to predatory threat has an acute buffering effect, subtly changing the neural and behavioral response towards threat and encouraging active responding. An association between active responding and lower c-Fos expression in the lateral septum is consistent with previous studies that highlight this region as an important neurobiological substrate of defensive aggregation.     

Amphetamine-induced aggression is enhanced in rats pre-treated with the anabolic androgenic steroid nandrolone decanoate

Aggression is one of the most commonly reported psychiatric side effects among anabolic-androgenic steroids (AAS) users. Furthermore, anecdotal stories say the aggression is even more profound when a current, or former, AAS-user consumes other drugs of abuse such as amphetamine and alcohol. In the present study, we examined the effect of amphetamine on defensive reactivity and defensive aggression in Sprague-Dawley rats after chronic AAS treatment (daily intramuscular [i.m.] injections with 15 mg/kg nandrolone decanoate [ND] for 14 days). Defensive reactions in rodents occur in response to a real threat, but also to perceived provocation, for example, elicited by innocuous stimuli as reaction towards the experimenter. The defensive reactivity and aggression test employed in this study evaluates each rat's reaction towards four different stimuli (I: approach of a rod; II: startle to an air puff; III: poking with a rod at the flanks, and IV: capturing with a gloved hand) at two different occasions. Immediately following the ND treatment period, no change in the defensive response was found. Nevertheless, an amphetamine challenge given 3 weeks after the last ND or vehicle injection induced a marked increased defensive aggressive response in the ND, compared to vehicle-pre-treated rats. Both ND- and vehicle-pre-treated rats receiving amphetamine were found to be more aggressive than comparable groups receiving a saline injection. It can be concluded that pre-treatment with ND modulates the behavioral response to amphetamine and induces long lasting changes in the behavioral response.     

Selection for the predisposition to catalepsy enhances depressive-like traits in mice

Immobility reaction or catalepsy is a natural passive defensive (lurking) behavioral response to the appearance of a predator. Selection for high predisposition to catalepsy has been performed in a population of (CBA x (CBA x AKR)) backcrosses of the crossing between mouse lines sensitive and resistant to catalepsy (VBA and AKR, respectively). A rapid increase in the number of animals with catalepsy has been observed: from 23% in backcrosses to 71% in the S3 generation. Selection for catalepsy does not affect mouse anxiety in the open field and plus-maze tests. However, S8 and S9 mice are characterized by a decreased motor activity in the open-field test and an increased immobility in the forced swim and tail suspension tests, which is interpreted as an increase in "depressiveness." The results indicate that genetically determined catalepsy is related to depressive-like characteristics of defensive behavior.     

Individual typological features of the dog behavior during the choice between food and avoidance of electrocutaneous stimulation

Two conditioned reflexes (CR) on flash were elaborated in five dogs in three experimental series. In one of them pressing on pedal were constantly reinforced with two pieces of liver, in other--escape or avoidance of skin stimulation with lifting of leg. In a third series, series of reinforcement choice, in front of animal with electrodes, fasting on leg, put the pedal. During of choice series defensive reactions were dominated in two dogs, alimentary reactions--three of them. For restoration alimentary behaviour in dog with great dominating of defensive reactions were many times reinforced with--food "passive" pressing legs on pedal during conditional stimuli, dog with less dominating of these reactions for restoration were enough a few coupling of conditional stimuli with food. With intensification electrocutaneus stimulation of legs or decreasing alimentary reinforcement we a success of diminishing of degree of alimentary reaction domination in one dog and in other ones temporarily changed of these domination on prevalence of defensive reactions. The results were compared with data, obtained in these dogs with technique of choice between probability and value of alimentary reinforcement. This comparison were permitted us of ranging dogs on scale "carefulness-riskiness", revealed of individual typological features of these animals.     

The role of the cerebral ganglia in the organization of feeding behavior in the pteropod mollusk Clione limacina]

The role of cerebral ganglia in switching from free swimming over to hunting behaviour in Clione limacina (Phipps) was studied. The cell bodies of central neurones giving processes to the sensory and motor nerves were mapped by retrograde axonal transport of Co2+ ions, and behavioural reactions under the extracellular electric stimulation of different ganglia areas were investigated. Comparison of morphological and behavioural data suggests main role of cerebral ganglia neurones in switching of behaviour from free swimming over to any of the three possible states: hunting (including food uptake), active or passive defensive behaviour.     

The role of fungicides in the physiology of higher plants: Implications for defense responses

Plants react to pathogen attack through a variety of active and passive defense mechanisms primarily related to the metabolism of phenolic compounds and oxidative metabolism. Thus the activation of defensive reactions is associated with the increased expression of a great number of genes that encode enzymes involved in the biosynthetic pathway of phenolic compounds. Similarly, the activation of oxidative metabolism precedes the expression of defense genes during plant-pathogen interactions, so both metabolic processes must exert a major function in directing the mechanisms to resist disease. Similarly, it has been suggested that certain fungicides used to mitigate or prevent pathogen attack may be involved in activating certain defensive responses of plants. However, the fact that such substances may influence the key steps of the phenolic and oxidative processes has scarcely been studied. Our work confirms the results proposed by other authors, who suggest that certain wide-spectrum fungicides, in addition to their antibiotic action against pathogens, may be involved in the activation of some defensive responses of plants.     

Reactions of hippocampal neurons at different stages of rat avoidance conditioning

The electrophysiological responses of neurons were compared in hippocampal slices from rats acquired and not acquired the passive avoidance reaction after the same conditioning procedure. Associative conditioning was accompanied by a gradual increase in the amplitude of the population spike evoked in CA1 area by stimulation of Schaffer collaterals. However, after reaching the learning criterion, the population spike significantly decreased. These phenomena were observed only at low (not maximal) intensities of test stimuli. After reaching the learning criterion, the paired-pulse facilitation was significantly higher in the slices prepared from the well-learned animals as compared with other groups (those having not reached the learning criterion, passive and active control). The obtained evidence validates the hypothesis that the observed intergroup differences stem from modifications of synaptic efficacy and suggests that after behavioral acquisition, plasticity induced by associative learning was substituted by other mechanisms probably related with declarative memory formation.