Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Escape Reaction”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 127 records · Page 7Linked to original sources
PubMed1983

Excitatory and inhibitory effects of repetitive stimulation of group I and II extensor afferents on homonymous motoneurons.

The repetitive firing of functionally isolated 143 extensor alpha motoneurons in response to homonymous group I and II tetanizations was studied in decerebrate cats. Of a total sample of 92 group I activated motoneuronal units, 76 motoneurons (82.6%) discharged phasically and 16 motoneurons (17.4%) discharged tonically at threshold or just suprathreshold tetanizations. Only 6 of the phasic motoneurons fired tonically when the stimulus strength was increased within the group I range. The firing rate of 8 phasic motoneurons increased at group I and II stimulations, but they retained their phasic discharge characteristics. The remaining 46 group I activated phasic motoneurons (60.1%) delivered tonic discharges when group II afferents were stimulated. Another group of 16 phasic motoneurons (21.1%) became tonic at group II tetanus, but their tonic discharge was usually interrupted by an inhibitory period, which coincided with an escape reaction of the animal. Out of 38 group II activated motoneuronal units, only 8 (21.1%) motoneurons discharged tonically at threshold or just suprathreshold tetanizations. The repetitive activity of these motoneurons was usually interrupted by an inhibitory period, which coincided with an escape reaction of the animal. This inhibition disappeared after procain application to the GS nerve, and was attributed to dominant inhibitory action of group II afferents mediating the sensation of pain. The remaining 30 (78,9%) motoneurons discharged phasically. Six of them remained phasic even at high threshold group II tetanus. The others gave tonic discharges when the stimulus strength was increased within the group II range. A great percentage of motoneurons discharged regularly with a fixed decoding ratio reflecting monosynaptic excitation. Some motoneurons discharged in multiple bands of impulse intervals due to a variable decoding ratio, which can be attributed to both monosynaptic and polysynaptic reflex discharge elicited by group I and/or II tetanizations. There were 6 motoneurons (4.2%), which discharged repetitively at stimulations of the GS, DP, and SUR nervers. These motoneurons were referred to "common motoneurons", which may participate in multiple motor actions such as fixation of a limb or as a part of the flexor reflex. SOL motoneurons usually discharged tonically at tetanizations within the group I range. The firing rate of these motoneurons usually decreased at tetanizations of the group II afferents of MG nerve. Conversely, tetanization of the group II afferents of SOL nerve usually exerted facilitatory effects on group II activated MG motoneurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1990

Treadmill locomotion and aversive effects induced by electrical stimulation of the mesencephalic locomotor region in the rat.

The effects of electrical stimulation of the "mesencephalic locomotor region" and adjacent dorsolateral tegmentum were assessed and compared in the same rats in freely moving conditions or when lightly anesthetized and suspended over a moving treadmill. In freely moving conditions, electrical brain stimulation (EBS) of this part of the mesencephalon elicited mainly aversive effects (escape reactions: violent running and explosive jumps), but also ipsiversive circling and "gnawing." On the treadmill, EBS induced flexions of hindlimbs followed by locomotion (stepping) or flexions only. In addition, it was found that locomotion and flexions on the treadmill were almost exclusively elicited by EBS of sites positive for escape reactions in freely moving conditions.

Animals↗
PubMed1990

Thermodynamic study of protein dynamic structure in the oxygen binding reaction of myoglobin.

We examined the flash photolysis of oxy complexes of sperm whale myoglobin (Mb) on the nanosecond time scale at ambient temperatures. In this time range, we can observe the geminate reaction of Mb with the O2 ligand existing in the protein matrix after the photodissociation from the heme iron. We found that the fraction of the geminate component to the total O2 photodissociation exhibited temperature dependences. The geminate fraction decreased with rising temperature, indicating that the protein fluctuation is enhanced at high temperature because of thermal agitation. However, the temperature-dependent behavior showed a break at 20 degrees C. Concerning the geminate O2 escaping reaction from the protein matrix to the solvent region, the activation energy above 20 degrees C (0.4 +/- 0.4 kcal/mol) is significantly lower than that below 20 degrees C (5.1 +/- 0.4 kcal/mol). Thermodynamic analysis on the basis of the transition state theory indicated that the O2 escaping reaction above 20 degrees C is entropy dominated whereas that below 20 degrees C is enthalpy dominated. The results were qualitatively compatible with the theoretical prediction by J. Kottalam and D. A. Case [1988) J. Am. Chem. Soc. 110, 7690-7697). Comparing the kinetic and thermodynamic process of the O2 geminate reaction among several Mbs, we concluded that the geminate O2 reaction with Mb is governed by the dynamic motion of the protein which is sensitively controlled by the static interaction of the heme moiety with the surroundings.

Animals↗
PubMed1996

Behavioral changes induced by GABA-receptor agonists in Lymnaea stagnalis L.

1. GABA, the GABAA receptor agonist, muscimol, and the GABAB receptor agonist, baclofen, were tested to study the involvement of the GABA neurotransmitter system in control of behaviour in the freshwater pulmonate snail, Lymnaea stagnalis L. Single injections of GABA (1-10 micrograms/ gbw) into the haemocoel of intact snails elicits a sequence of behavioural changes subsequently affecting feeding, locomotion, escape reactions, male mating behaviour and respiration. 2. Both muscimol and baclofen mimic distinct aspects of GABA action implying that the GABA action is mediated by both types of receptors. 3. The modulatory actions of GABA, muscimol, and baclofen on feeding were manifested as opening of the mouth and triggering of specific radular movements (e.g., protraction, retraction, rasping). 4. Baclofen (1-10 micrograms/gbw) evoked the full erection of the penis for a time long enough for natural copulation, while GABA itself caused only partial eversion of the preputium. Muscimol was less effective than GABA. The latency to penis eversion varied in a dose-dependent manner. The data emphasize the participation of baclofen-sensitive receptors in control of reproduction. 5. GABA and baclofen induced withdrawal of the head and anterior part of the foot accompanied by arrest of locomotion and respiration could be considered to be an escape reaction. 6. Muscimol (1-5 micrograms/gbw) failed to elicit withdrawal reactions but caused the loss of normal orientation and longitudinal contractions of the foot. 7. All the agents tested inhibited locomotion in a dose-dependent manner, for a substantial period of time. A decrease in total locomotor activity lead to the failure of animals to attach to the underlying surface, to have foot contractions and also to diminish locomotor velocity. 8. The majority of animals maintained the stereotyped complex reactions of respiration, but with restricted clockwise turning of the shell after drug treatment. 9. All the substances were shown to shift the background behavioural state characterised by high BSSs to a state similar to "rest" which was awarded a low BSS. It is concluded that the GABA neurotransmitter system can play an important role in activation and coordination of neuronal ensembles underlying behaviour and behaviour selection in Lymnaea stagnalis L.

Animals↗
PubMed1982

Participation of thalamic nuclei in the acquisition of conditioned avoidance reflexes in rats. IX. Lesions of the nucleus reticularis.

Bilateral symmetric lesions of the anterior part of the nucleus reticularis thalami (RET) strongly reduced the preoperatively learnt avoidance responses in Long-Evans hooded rats. A great retention loss, significantly prolonged reaction times and slow incorrect escape reactions in the first postoperative session in a simple runway task were corrected in the relearning period. The relearning of directional change and of a 2:2 alternation schedule in the Y-maze was rather difficult; it delayed and remained on a lower performance level with a not correctable side preference. A great retention loss in the pole-climbing test was not compensated in the relearning period. The experimental data suggest that the RET plays an important role in the inhibition of incorrect responses.

Animals↗
PubMed1982

Cardiovascular reactions from hypothalamic self-stimulation in the rat.

Arterial blood pressure (BP) and heart rate (HR) were continuously recorded during lateral hypothalamic self-stimulation with optimal stimulus parameters in rats. Hyper-hypotensive, hypertensive and hypotensive reactions were observed during separate self-stimulation, and the biphasic type considerably prevailed over other types of reactions. During the single cycles of self-stimulation hyper-hypotensive and hypertensive reactions with different heart rate reactions also occurred. In this case the biphasic type was seen in 75% of all reactions, whereas the hypotensive type occurred in 25% of the cases. The main type of BP reaction (92%) during continuous self-stimulation for 60-240 min was a gradual increase of the mean BP level from 15 to 40 mm Hg against initial values (p less than 0.001), that depended on the duration of self-stimulation. Changes of HR were more variable: tachycardia and bradycardia were seen approximately with the same frequency. Comparative analysis of cardiovascular reactions during hypothalamic SS and escape reactions provoked by ventromedial hypothalamus stimulation revealed some peculiarities of autonomic manifestations during positive and negative emotional reactions. The results of this comparison raises the question of a stress-reaction during self-stimulation behaviour.

Animals↗
PubMedDate not supplied

[Hypothalamic neurons and defensive reflexes].

Identified groups of neurons in positive (the lateral hypothalamic area, the lateral preoptic area) and negative (the ventromedial hypothalamus) emotional regions were examined under the different levels of food motivation and emotionally positive and negative intracranial stimulation. The responses of the neurons in classical and operant conditioning were different. This difference was manifested in tonic (during location of the animal into the chamber) and phasic alterations of neuronal activity and at certain stages of conditioned reflex performance. During classical conditioning were revealed the reciprocal relations in unit activity of the positive and negative emotional structures. During the operant reflex more complicated pattern of reactions was observed being connected with realization of a necessity of removing from the negative influences. During defensive reflex in the cases of classical conditioning and avoidance reaction reinforcement was related with engaging the negative emotional mechanisms while in the course of escape reaction the positive emotional mechanism being engaged.

Animals↗
PubMed2006

Postnatal development of conditioned reflex behavior: comparison of the times of maturation of plastic processes in the rat hippocampus.

The formation of conditioned reflex fear, escape responses, and conditioned avoidance responses during acquisition of a conditioned two-way avoidance reflex was studied in rats of different ages. Rats aged 16-17 days acquired the conditioned reflex but not the escape reaction or the conditioned avoidance response; acquisition efficiency was higher than in adult rats. Escape responses appeared from postnatal day 18. The ability to acquire this type of learning was complete by age 3-4 weeks. Maturation of the mechanisms of the "classical" (the fear phase) and operant (transfer to another sector in response to the unconditioned stimulus) components did not facilitate acquisition of the conditioned two-way avoidance reflex until the middle of postnatal week 4. Learning efficiency in four-week-old rats was lower than in adults. It is suggested that the maturation of different types of memory may be associated with the periods at which plastic processes develop in the hippocampus.

Aging↗
PubMed1985

An assessment of the antinociceptive and aversive effects of stimulating identified sites in the rat brain.

At many sites in the brain electrical stimulation with low current intensity is both aversive and causes antinociception. In view of the well documented antinociception caused by various types of stress and pain it is possible that in some parts of the brain the antinociception is secondary to the stress of the stimulation. At 114 sites in the rat brain the intensity of stimulation required to evoke an aversive response has been compared with the antinociceptive current intensity. Only stimulation in the dorsal hippocampus and pretectal area caused antinociception without significant aversion. Strong aversion resulted from stimulation of 46% of the sites including the central gray and nucleus raphe magnus. Antinociception was significantly correlated with the aversiveness of the stimulation although in 15% of the stimulation sites strong aversion was seen with no antinociception. It is concluded that there can be little justification in assigning a primary antinociceptive role to a brain area which evokes strong escape reactions when stimulated.

Animals↗
PubMed1996

Effects of the blockade of opioid receptor on defensive reactions elicited by electrical stimulation within the deep layers of the superior colliculus and DPAG.

The effects of peripheral administration of naloxone and naltrexone on aversive thresholds (freezing and escape reactions) elicited by electrical stimulation of the midbrain tectum were determined. Naloxone caused a significant increase in the freezing and flight thresholds elicited by electrical stimulation in the deep layers of the superior colliculus and of dorsal regions of the periaqueductal grey matter, as compared with controls. These effects were confirmed by the peripheral administration of naltrexone. These findings suggest that opioid receptors can modulate aversive behaviour elicited by midbrain tectum stimulation.

Animals↗
PubMed1988

Escape behavior in the cockroach: distributed neural processing.

Escape reactions are often considered to be among the simplest behaviors. The nerve circuits guiding these reactions are also generally thought to be simple. For instance, in several species a single interneuron is sufficient to trigger normal escape. The evasive response of the cockroach, however, appears to be more complex both behaviorally and physiologically. In this review, several complications of the behavior are pointed out, based on a recent computer-graphic analysis of the leg movements. Next described is the cooperative role of several interneurons--not just one--in evoking an escape turn away from the stimulus. A model of this multicellular code for stimulus direction is then presented that correctly predicts the turning behavior under many different experimental conditions. Finally, an overall scheme of the information processing for escape behavior is presented.

Animals↗
PubMed1993

[A pharmacological analysis of pentagastrin-modulated behavior evoked by stimulation of the ventromedial hypothalamus].

The purpose of the present investigations was to examine the neurochemical mechanisms of modulatory effect of pentagastrin (PG) on escape reaction elicited by the threshold electrical stimulation of the ventromedial hypothalamus (VMH) in rabbits. PG administration (35 mcg/kg intraventricularly) was found to transform escape into feeding. This phenomenon was shown to begin at 20 min and to last to 150 min after PG injection. The animals were treated with various antagonists to some classic neurotransmitters of the central nervous system. Kalipsol (0.25, 0.5 mg/kg intravenously) and ketanserin (0.1 mg/kg intravenously) were found to restore feeding into escape. GABA-ergic antagonist baclofen (0.25, 0.5 mg/kg) was demonstrated to shorten to about 30 min the time of feeding after PG administration. Both inderal-beta-adreno-blocker (0.25, 0.5, 1.0 mg/kg) and M-choline antagonist atropine (0.25, 0.5 mg/kg) were found to be ineffective in escape restoration in response to VMH stimulation. The experimental results suggest the important role of N-cholinergic and serotoninergic brain structures in PG transformation of escape elicited from the VMH into feeding.

Animals↗
PubMed2001

Exploitation of an ancient escape circuit by an avian predator: relationships between taxon-specific prey escape circuits and the sensitivity to visual cues from the predator.

The painted redstart Myioborus pictus uses visual displays to flush, pursue, and then capture an abundance of brachyceran Diptera that are equipped with giant fiber escape circuits. This paper investigates the relationships between features of the giant fiber system, the structure of visual stimuli produced by redstarts and their effectiveness in eliciting escape reactions by flies. The results show that dipterous taxa having large-diameter giant fibers extending short distances from the brain to motor neurons involved in escape are flushed at greater distances than taxa with longer and small-diameter giant fibers. The results of behavioral tests show the importance of angular acceleration of expanding image edges on the compound eye in eliciting escape responses. Lateral motion of stimulus profile edges as well as structured visual profiles additionally contribute to the sensitivity of one or more neural systems that trigger escape. Retinal subtense and angular velocity are known to trigger physiological responses in fly giant fiber circuits, but the contributions of edge length and lateral motion in a looming stimulus suggest that escape pathways might also receive inputs from circuits that are tuned to different types of motion. The present results suggest that these several properties of escape pathways have contributed to the evolution of foraging displays and plumage patterns in flush-pursuing birds.

Animals↗
PubMed1997

Altered excitability of the crayfish lateral giant escape reflex during agonistic encounters.

The excitability of the lateral giant escape reflex of socially dominant and submissive crayfish at rest and during agonistic encounters was studied and compared. During agonistic encounters the excitability of the lateral giant reflex falls, substantially in subordinates and slightly in dominants, whereas at rest excitability seems to be independent of social status. Thus, paradoxically, socially dominant animals are more likely to execute lateral giant escape reactions during interactions than are subordinates. It is suggested that subordinates under threat of attack tend to engage circuitry involved in flexible, nonreflex ("voluntary") types of escape not mediated by giant neurons and therefore inhibit giant neuron-mediated reflex circuitry that produces prompt, but less adaptive, responses. In contrast, dominants go about their business, mainly ignoring their conspecifics and relying on reflex escape to protect them from unexpected attack. Consistent with this view, escape of subordinates during agonistic encounters is mediated by nongiant, not reflex, circuitry. These observations and their interpretation suggest a possible functional role for recently described social status-dependent serotonergic modulation of the lateral giant reflex, which is inhibitory in sign in subordinates and facilitatory in dominants.

Agonistic Behavior↗
PubMed1984

Defeat, learned submissiveness, and analgesia in mice: effect of genotype.

Defeat-induced unconditioned and conditioned behaviors of C57BL/6 and DBA/2 mice were assessed in a social-learning paradigm. Upon bites, mice of the DBA strain reacted with significantly more escape reactions, while C57 mice showed more immobility, crouch, and defensive sideways and upright postures. Clear genotype-dependent patterns were also evident from the conditioned responses recorded 24 h after defeat. DBA mice displayed more escape and defensive sideways and upright postures upon contact with a nonaggressive partner mouse; in contrast, C57 mice reacted with more immobility and crouch. With an increasing number of bites the sum of learned responses increased in C57 mice while it decreased in mice of the DBA strain. This decrement was paralleled by an increase in the analgesic response measured on the hot plate in defeated DBA mice. The possible role of endogenous opioids in the genotype-dependent interaction of defeat-induced learned submissiveness and analgesia is discussed.

Aggression↗
PubMed1999

Effects of serotonergic and opioidergic drugs on escape behaviors and social status of male crickets.

We examined the effects of selective serotonin depletion and opioid ligands on social rank and related escape behavior of the cricket Gryllus bimaculatus. Establishment of social rank in a pair of males affected their escape reactions. Losers showed a lower and dominants a higher percentage of jumps in response to tactile cercal stimulation than before a fight. The serotonin-depleting drug alpha-methyltryptophan (AMTP) caused an activation of the escape reactivity in socially naive crickets. AMTP-treated animals also showed a lower ability to become dominants. With an initial 51.6+/- 3.6% of wins in the AMTP group, the percentage decreased to 26+/-1.6% on day 5 after injection. The opiate receptor antagonist naloxone affected fight and escape similarly as AMTP. In contrast to naloxone, the opioid agonist [d-Ala(2), N-Me-Phe(4), Gly(5)-ol]-enkephalin decreased escape responsiveness to cercal stimulation in naive and subordinate crickets. We suggest that serotonergic and opioid systems are involved in the dominance induced depression of escape behavior.

Animals↗
PubMed2005

Gabaergic regulation of the neural organization of fear in the midbrain tectum.

In midbrain tectum (MT) structures, such as the dorsal periaqueductal gray (dPAG), the superior colliculus (SC) and the inferior colliculus (IC) GABAergic neurons exert a tonic control on the neural substrates involved in the expression of defensive reactions. In this review, we summarize behavioral, immunohistochemical (brain Fos distribution) and electrophysiological (auditory evoked potentials) data obtained with the reduction of GABA transmission by local injections of a GABA receptor blocker (bicuculline, BIC) or a glutamic acid decarboxylase inhibitor (semicarbazide, SMC) into the MT. Distinct patterns of Fos distribution were obtained following the freezing and escape reactions induced by MT injections of SMC and BIC, respectively. While only the laterodorsal nucleus of the thalamus was labeled after SMC-induced freezing, a widespread increase in Fos expression in the brain occurred after BIC-induced escape. Also, injections of SMC into the IC increased the auditory evoked potentials recorded from this structure. It is suggested that GABAergic mechanisms of MT are also called into play when sensory gating of the MT is activated during different emotional states.

Animals↗
PubMedDate not supplied

[Effects of intracerebroventricular administration of a caspase-3 inhibitor Z-DEVD-FMK on behavior of rats].

Rats received intracerebroventricular injections of z-DEVD-FMK (caspase-3 inhibitor) or z-FA-FMK (control peptide) in a dose of 3 nmol. Administration of z-DEVD-FMK significantly decreased the number of avoidance reactions in some blocks of trials in active avoidance (shuttle box) learning. However, only slight effect of the caspase inhibitor across the session was found. Z-DEVD-FMK impaired development of some essential components of the two-way active avoidance performance, such as escape reaction, conditioned fear reaction, and inter-trial crossings. Z-DEVD-FMK did not impair working memory in the spontaneous alternation behavior paradigm. Z-DEVD-FMK affected neither emotionality nor locomotor activity in the open-field test. It also did not influence behavior in the light-dark chamber. Measurement of caspase-3 activity in rat brain regions involved in active avoidance learning revealed z-DEVD-FMK-related inhibition of the enzyme activity most pronounced (about 30%) in the fronto-parietal cortex; a similar effect was close to significant in the hippocampus. The results suggest the involvement of brain caspase-3 in selected forms of learning.

Animals↗