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Results for “Escape Reaction”

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At least 217 records · Page 12Linked to original sources
PubMed1985

Effects of hypothalamic lesions on central gray stimulation induced escape behavior and on withdrawal reactions in the rat.

The effects of unilateral--medial or lateral--hypothalamic lesions were studied with regard to both switch-off (i.e., escape) responding induced by central gray (CG) stimulation and responsiveness of the same animals to peripherally-applied electrical or thermal stimulation. Medial hypothalamic (MH) lesions were found to reduce--but not abolish--the efficiency of CG stimulations applied on the side of the MH lesion, while the efficiency of contralaterally applied CG stimulations remained unchanged. Furthermore, such lesions enhanced the responsiveness to peripheral nociceptive stimuli on whatever body side they were applied. Lateral hypothalamic lesions were found to only slightly--or not at all--affect the efficiency of CG stimulations, while they enhanced the responsiveness to peripheral nociceptive stimuli on either side of the body. These results suggest that the hypothalamus does not exert a univocal control over both centrally induced escape behavior and peripherally induced withdrawal reactions.

Animals↗
PubMed1993

The periaqueductal gray and defensive behavior: functional representation and neuronal organization.

Recent findings suggest that the periaqueductal gray (PAG) can be subdivided on the basis of its anatomical connections and functional representation of cardiovascular and behavioral functions. This new scheme of subdivision postulates the existence of 4 major longitudinal columns located dorsomedial, dorsolateral, lateral and ventrolateral to the aqueduct. Attention has focussed on the lateral and ventrolateral columns, because they contain topographically distinct groups of neurons whose activation results in different forms of defensive or protective reactions. Reactions evoked from the lateral PAG column are associated with somatomotor and autonomic activation and are characteristic of an organism's response to superficial or cutaneous noxious stimuli, whereas reactions evoked from the ventrolateral PAG column are associated with somatomotor and autonomic inhibition and appear to correspond to an organism's response to deep or visceral noxious stimuli. Furthermore, the neurons of these two columns possess some degree of somatotopic and viscerotopic organization and send axon collaterals to multiple targets in the medulla. This model of PAG neuronal organization outlines the basic architectural features of a network involved in the coordinated expression of certain types of defensive/protective reactions.

Animals↗
PubMedDate not supplied

Effect of lesions of the ventral noradrenergic bundle on the two-way avoidance behavior in rats.

Bilateral electrolytic lesions of the ventral noradrenergic bundle (VB) were performed in Wistar male rats. Seven to eight days after the surgery animals were trained for two-way avoidance behavior (10 days, 15 trials per day). Lesions of the VB facilitated avoidance acquisition and slightly increased intertial responses. The latency of avoidance reaction as well as latency of escape was unchanged in VB-lesioned animals. The possible role of VB in mechanism of learning is discussed. It is pointed out that VB may play an opposite role to the dorsal noradrenergic bundle which is known to facilitate learning.

Animals↗
PubMed2005

Cognitive paralysis in an emergency: the role of the supervisory attentional system.

Many witnesses attest that victims of a disaster often perish because they 'freeze' in the face of danger. It has been proposed that this cognitive paralysis occurs due to temporal and cognitive constraints on survival response times while leaving open the question of which cognitive component is implicated in this behavior. This paper proposes, firstly, that the temporal constraints which occur during an emergency inhibit the functioning of the supervisory attentional system (SAS), which leads to the victim showing: (1) an appropriate response, if trained; (2) stereotypical or otherwise irrational behavior, if untrained; or (3) cognitive paralysis. Secondly, that the main role of the SAS is to operate as a temporal buffer, enabling a survival response to be prepared prior to facing a life-threatening event and not as a real-time immediate responder. It is argued that the initial cognitive paralysis differs at the cognitive and neurological levels from the more prolonged hypoactive behavior commonly seen in victims rescued from disasters and which is considered to be a form of disassociative reaction.

Cognition↗
PubMed1996

[Anti-infective defence strategies and methods of escape from entomologic pathogens under immunologic control of insects].

Insect immunity comprises a complex of several distinct systems, both haemocytic and humoral in nature, that cooperate together in a more or less coordinated way to provide protection of the body cavity from invading microorganisms. Insects can respond to infections by a selective synthesis of haemolymph immune proteins that are responsible for antibacterial immunity. Antibacterial activity of insect blood is attributable to innate compounds such as lysozome, and to induced polypeptides or small basic proteins absent in non-immunized insects. The cecropins and attacins in Lepidoptera, and diptericins in Diptera are the inducible antibacterial immune proteins well defined biochemically. Bacterial pathogens and some parasites of insects, preferably entomogenous rhabditid nematodes, have developed the mechanism by which they may counteract insect immunity. This phenomenon is realized either by escaping immune reactions or by degrading antimicrobial factors of haemolymph in an active process. Passive resistance of parasites to insect immunity is a result of a strong evolutionary pressure on parasites to develop mechanisms to escape insect immune reactions or to minimize their effectiveness through changes in the parasite itself. Active resistance to the insect non-self response system involves a partial or total destruction of immune proteins by extracellular proteinases released during parasitism.

Animals↗
PubMed2006

Picrotoxin blocks the anxiolytic- and panicolytic-like effects of sodium valproate in the rat elevated T-maze.

The effect of acute sodium valproate administration, an anxiolytic and putative panicolytic drug, was evaluated in rats tested in the elevated T-maze, an animal model that measures two defensive reactions: avoidance (inhibitory avoidance), related to generalized anxiety, and escape (escape from open arms), related to panic. Additionally, the involvement of gamma-aminobutyric acid (GABA) neurotransmission in sodium valproate effects was studied by picrotoxin co-administration. Sodium valproate (300 mg/kg, intraperitoneally, 30 min before the test) impaired both avoidance latency (time to leave the closed arm) and one-way escape (latency to enter the closed arm) indicating anxiolytic and panicolytic effects, respectively. Pre-treatment with picrotoxin (0.5 mg/kg, intraperitoneally, 5 min before sodium valproate administration) blocked the effects of sodium valproate on inhibitory avoidance and one-way escape. No locomotor effect was seen in the open-field. These data suggest that sodium valproate exerts anxiolytic-like and panicolytic-like effects in the elevated T-maze and that these effects were mediated by picrotoxin-sensitive GABA type A receptors.

Animals↗
PubMed2005

Modeling human behaviors and reactions under dangerous environment.

This paper describes the framework of a real-time simulation system to model human behavior and reactions in dangerous environments. The system utilizes the latest 3D computer animation techniques, combined with artificial intelligence, robotics and psychology, to model human behavior, reactions and decision making under expected/unexpected dangers in real-time in virtual environments. The development of the system includes: classification on the conscious/subconscious behaviors and reactions of different people; capturing different motion postures by the Eagle Digital System; establishing 3D character animation models; establishing 3D models for the scene; planning the scenario and the contents; and programming within Virtools Dev. Programming within Virtools Dev is subdivided into modeling dangerous events, modeling character's perceptions, modeling character's decision making, modeling character's movements, modeling character's interaction with environment and setting up the virtual cameras. The real-time simulation of human reactions in hazardous environments is invaluable in military defense, fire escape, rescue operation planning, traffic safety studies, and safety planning in chemical factories, the design of buildings, airplanes, ships and trains. Currently, human motion modeling can be realized through established technology, whereas to integrate perception and intelligence into virtual human's motion is still a huge undertaking. The challenges here are the synchronization of motion and intelligence, the accurate modeling of human's vision, smell, touch and hearing, the diversity and effects of emotion and personality in decision making. There are three types of software platforms which could be employed to realize the motion and intelligence within one system, and their advantages and disadvantages are discussed.

Artificial Intelligence↗
PubMedDate not supplied

Action of 6-hydroxydopamine on two parameters of motor learning.

In rats injected in the cerebral ventricle with 250 micrograms of 6-hydroxydopamine a significant blockade of the improvement of swimming performance due to training occurs. The central injection of 6-OHDA leads to a lengthening of the total latency time (LT) of active conditioned reaction in shuttle box and of the LT of netative escape responses during learning, but not of the positive avoidance responses. 6-OHDA injected after the learing schedule (12 days) has no effect on the LT during relearning and extinction. Therefore a partial destruction of central monoaminergic, and especially of dopaminergic, neurons impairs particularly the acquisition but not the retention of the motor program.

Animals↗
PubMed1983

The effect of instrumentalization of inborn reaction on its transformation into contrary directed escape response in dogs and the problem of reinforcement.

Transformation of inborn reaction of leg flexion into conditioned escape response of leg extension was studied. The model of the so called precise reflex was used. A dog could avoid or escape the shock applied to the paw by placing this paw in a narrow ,,safety zone located at a definite height above the floor. When the shock is applied to the paw located below this zone, the escape response is flexion, i.e., it coincides with the inborn reaction. When the paw is lifted above this zone, the escape response is extension, i.e., it is opposite to the inborn response. Success of such extension response acquisition depended on the sequence of training conditions. The dogs of Group I at the beginning were accustomed to escape from shock by lifting the paw into the ,,safety zone, i.e., inborn reaction was instrumentalized. A subsequent formation of conditioned extension was extremely difficult and it did not became strong in spite of a very long training. Lowering the paw into the ,,safety zone was usually slow. The dogs of group II were trained from the very beginning to escape from shock by leg extension. Contrary to the results obtained on group I this conditioned response was perfectly established. It was formed rapidly, only when active extension was paired regularly with termination (during extension) of the shock. It is suggested that conditioned connection from one functional center to another is formed and becomes stronger if evoked activity of the first center decreases during (or immediately after) the excitation of the second center.

Animals↗
PubMedDate not supplied

[Substance P and the ethanol-evoked changes in the independent motivated behavioral reactions of rabbits].

Ethanol (0.5 g/kg) administered intravenously led to alterations in central mechanisms of feeding and escape, elicited by threshold electrical stimulation either of lateral or of ventromedial hypothalamic centers of the rabbit. Subsequent intravenous injection of substance P (30 mcg/kg) restored the excitability of the ventromedial hypothalamus and facilitatory effects on this motivational center of the midbrain reticular formation. The restoration of both inhibitory influences of the dorsal hippocampus and facilitatory ones of the midbrain reticular formation on the excitability of the lateral hypothalamus was also observed after SP administration. Data obtained suggest that oligopeptides could be used to increase the tolerance to ethanol or to cure the negative acute effects of alcohol in motivated behaviours.

Animals↗
PubMed1988

Defense reaction elicited by microinjection of kainic acid in the medial hypothalamus of the rat.

In order to localize groups of neurons commanding the defense reaction, a subtoxic dose (66 pmol) of kainic acid was microinjected into the medial hypothalamus of the rat. After drug treatment, the animals were placed inside a shuttle-box for 15 min and the number of midline crossings, rearings and forward leaps were recorded. Autonomic changes such as occurrence of micturition and defecation were also measured. Injection of kainic acid significantly increased locomotion, rearing and micturition, indicating that the medial hypothalamus of the rat contains perikarya/dendrites of neurons integrating the defense reaction.

Animals↗