Escape Response Latency Research Articles

A Computational Model of the Escape Response Latency in the Giant Fiber System of Drosophila melanogaster.

The giant fiber system (GFS) is a multi-component neuronal pathway mediating rapid escape response in the adult fruit-fly Drosophila melanogaster, usually in the face of a threatening visual stimulus. Two branches of the circuit promote the response by stimulating an escape jump followed by flight initiation. A recent work demonstrated an age-associated decline in the speed of signal propagation through the circuit, measured as the stimulus-to-muscle depolarization response latency. The decline is likely due to the diminishing number of inter-neuronal gap junctions in the GFS of ageing flies. In this work, we presented a realistic conductance-based, computational model of the GFS that recapitulates the experimental results and identifies some of the critical anatomical and physiological components governing the circuit’s response latency. According to our model, anatomical properties of the GFS neurons have a stronger impact on the transmission than neuronal membrane conductance densities. The model provides testable predictions for the effect of experimental interventions on the circuit’s performance in young and ageing flies.

Influence of dog presence on the tolerance and evaluation of aversive stimulation

This study aimed to investigate the effects of the presence of a domestic dog in the evaluation and tolerance of auditory aversive stimulation. Eighteen undergraduate college students participated. We analysed the latency of escape response from the aversive sounds and evaluation of the session through a semantic differential in three conditions: no distractors, a book of paintings as a distractor, and a dog as a distractor. Latency of escape response was significantly higher in the presence of a dog and participants also evaluated the session more positively, suggesting that dogs can positively affect the perception of an aversive stimulation.

Maternal diet and larval diet influence survival skills of larval red drum Sciaenops ocellatus.

Larval red drum Sciaenops ocellatus survival, turning rate, routine swimming speed, escape response latency and escape response distance were significantly correlated with essential fatty-acid (EFA) concentrations in eggs. Of the five traits that varied with egg EFA content, two (escape response latency and routine swimming speed) were significantly different when larvae were fed enriched diets compared with the low fatty-acid diet, indicating that the larval diet can compensate for some imbalances in egg composition. Turning rate during routine swimming and escape response distance, however, did not change when larvae predicted to have low performance (based on egg composition) were fed an enriched diet, indicating that these effects of egg composition may be irreversible. Escape response distances and survival rates of larvae predicted to perform well (based on egg composition) and fed highly enriched diets were lower than expected, suggesting that high levels of EFA intake can be detrimental. Altogether, these results suggest that both maternal diet, which is responsible for egg EFA composition, and larval diet may play a role in larval survivorship and recruitment.

Repeatability of escape response performance in the queen scallop (Aequipecten opercularis)

In order for natural selection to operate, physiological and behavioural traits must exhibit both inter-individual variability and intra-individual consistency (i.e. repeatability) in performance. In this study, we describe individual variation and temporal repeatability in the escape responses of the queen scallop, Aequipecten opercularis, and determine whether individuals exhibited consistently high or low rankings in different aspects of the escape response. Five measures of individual performance were recorded on four occasions (days 0, 2, 7 and 28), providing proxies for sensory acuity (response latency), immediate and sustained swimming performance (burst and average clap rates), and swimming endurance (total number of claps and total time spent clapping). All components of the escape response exhibited significant inter-individual variability (all P<0.0001). Escape response latency, burst clap rate, total number of claps and total duration spent clapping maintained significant repeatability over 28 days (all P<0.016). Average clap rate was repeatable in the short term (2 days, P<0.0001) but repeatability declined by 28 days (P=0.097). Concordance analysis indicated that individuals maintained the same performance rankings over time for each component of the escape response (all P<0.001). In addition, some individuals ranked as consistently high or low performers across response latency, burst and average clap rate, and total number of claps. An individual's ability to evade predators through the provision of an escape response of an appropriate magnitude, subject to physiological, behavioural and organismal constraints, will have clear fitness-related consequences.

Maturation of escape circuit function during the early adulthood of cockroaches Periplaneta americana.

During postembryonic development of insects, sensorimotor pathways, which generate specific behaviors, undergo maturational changes. It is less clear whether such pathways are typically stable, or undergo further maturation, during the adult stage. In the present study, we have examined this issue by multilevel analysis of a simple model system, the escape behavior of the cockroach, from identified synapses to behavior. We show that the escape system is highly responsive immediately after the molt to adulthood, but that the latency of escape responses was not at its typical value immediately after the molt to adult. The latency of escape behavior increased over the first 30 days of adult life, perhaps indicating maturational adjustments of the escape sensorimotor pathway. The first station in the escape circuitry is the synaptic connections between the cercal wind receptors and the giant interneurons. We measured unitary excitatory synaptic potentials between single sensory neurons and an identified giant interneuron (GI(2)). We found a decrease in the synaptic strength between identified cercal hairs from a single column and GI(2) over the first month after the adult molt. Consequently, the latency and the number of action potentials of GI(2) in response to natural stimuli increased and decreased respectively during this time. Thus, we show that both behavioral performance and the wind sensitivity of GI(2) decreased over the first month after molt. We conclude that the cockroach escape system undergoes further sensorimotor maturation over a period of 1 month, and that cellular changes correlate with, or predict, some changes in behavioral performance.

Pharmacological profiles of a novel opioid receptor-like1 (ORL(1)) receptor antagonist, JTC-801.

Pharmacological effects of a novel opioid receptor-like1 (ORL(1)) receptor antagonist, [N-(4-amino-2-methylquinolin-6-yl)-2-(4-ethylphenoxymethyl) benzamide monohydrochloride] (JTC-801), were examined in in vitro and in vivo. JTC-801 inhibited the binding of [(3)H]-nociceptin to human ORL(1) receptors expressed in HeLa cells with a K(i) value of 44.5 nM. JTC-801 completely antagonized the suppression of nociceptin on forskolin-induced accumulation of cyclic AMP (IC(50) : 2.58 microM) using ORL(1) receptor expressing HeLa cells in vitro. In in vivo, when given intravenously at dosages of 0.01 mg kg(-1) and above, or orally at dosages 1 mg kg(-1) and above, JTC-801 antagonized the nociceptin-induced allodynia in mice. Effects of JTC-801 on various nociceptive models were examined. In mouse hot-plate test, JTC-801 prolonged escape response latency (ERL) to exposed heat stimulus with minimum effective doses (MED) of 0.01 mg kg(-1) by i.v. or 1 mg kg(-1) by p.o. In the rat formalin test, JTC-801 reduced both the first and second phases of the nociceptive response with MED of 0.01 mg kg(-1) by i.v. administration or 1 mg kg(-1) by p.o. administration. This anti-nociceptive action of JTC-801 was not inhibited by naloxone (10 mg kg(-1), s.c.). We have demonstrated that JTC-801 antagonizes the ORL(1) receptor response, and that JTC-801 has efficacious and potent anti-nociceptive effects in acute pain animal models not only by intravenous injection but also oral administration. These results suggest that JTC-801 may represent a new class of analgesics.

Effects of systemic morphine on escape latency and a hindlimb reflex response in the rat

The present study uses focal electrical stimulation of myelinated nociceptors to simultaneously assess behavioral responses that are organized at spinal and supraspinal sites in the rat. Hindlimb reflex amplitude and the latency to operant escape responses by a forelimb were recorded for each stimulus presentation to a hindlimb across a wide range of intensities. This paradigm provided a tool whereby effects of morphine on conscious escape responses could be delineated from effects on a segmental flexion reflex over a range of doses. Administration of morphine (3 mg/kg and 10 mg/kg, subcutaneously) increased the latency of escape responses and decreased the amplitude of reflex responses in a dose-dependent manner. However, morphine produced a greater suppression of reflex responses compared with the increase in effects on escape latencies. The effects of morphine on escape latency were not expressed at the highest stimulus intensities (0.6 to 0.8 mA), whereas reflex responses were attenuated at all suprathreshold stimulus intensities. Thus, electrically evoked, spinal-mediated responses of rats are not affected by morphine in the same manner as electrically evoked supraspinal-mediated nociceptive behaviors. However, both measures confirm evidence that responses elicited by activation of myelinated afferents are less powerfully affected by morphine than responses to input from unmyelinated nociceptors.

Capsaicin or feeding with red peppers during gestation changes the thermonociceptive response of rat offspring

Capsaicin is responsible for the pungent sensation produced by red peppers on the body's mucous membranes. This substance is found naturally in the gender Capsicum, widely used in the diet of different cultures in America, Asia, and Africa. In this paper we used the hot plate model (53 ± 0.5° C) to study the effect of acute thermonociceptive stimulus on escape response latency in the offspring of rats that were treated during gestation, either with an aqueous red pepper solution ( Capsicum frutescens, approximately 2.75 mg of capsaicin in 1 ml/day, by gavage during the second week), or with capsaicin (0.5 mg/day SC, during the second week). These groups were compared with their respective controls. We found that the difference between the manipulated control group and the one given the aqueous red pepper solution was 41.33%, and between the vehicle control and the one treated with capsaicin was 30.59%. These increments on the escape response latency were statistically significant. Our results show that both treatments, the aqueous red pepper extract and low doses of capsaicin on pregnant rats, produce an increment on escape response latency due to a thermonociceptive stimulus.

A lever-release version of the conditioned avoidance response paradigm: Effects of haloperidol, clozapine, sulpiride, and BMY-14802

Rats trained on a lever-release version of the conditioned avoidance response (CAR) task were used to test the behavioral effects of established and putative antipsychotic drugs. Baseline CAR latencies decreased as the conditioned-unconditioned stimulus interval was shortend from 500 to 250 ms. Haloperidol, clozapine, and BMY-14802 decreased successful avoidance responses and increased avoidance latencies in a dose-dependent manner without affecting the latency of escape responses. In contrast, sulpiride failed to affect either successful avoidance response rates or avoidance latency. Sulpiride, however, significantly attenuated d-amphetamine-induced locomotion and rearing compared to vehicle-treated controls. Similar effects of these antipsychotics have been reported on shuttlebox avoidance, and these results now are confirmed in a CAR paradigm that achieves greater control over behavior. Because this paradigm elicits a discrete forelimb response without activating numerous muscle groups, it is potentially useful as a tool for examining neuronal mechanisms underlying the behavioral effects of antipsychotic drugs.

Habenula as a Relay in the Descending Pathway from Nucleus Accumbens to Periaqueductal Grey Subserving Antinociception

This study explored the possibility of a relay at habenula for the descending neural pathway of antinociception. The latency of the escape response elicited by radiant heat on the snout of the rabbit was taken as index of nociception. (1) Microinjection of 20 micrograms of morphine into nucleus accumbens resulted in a one-fold increase in nociceptive threshold 20-40 min after the injection. This effect of morphine was markedly attenuated by naloxone or met-enkephalin antiserum administered to the nucleus habenula, suggesting that the release of met-enkephalin in habenula is essential for the antinociception induced by morphine injected into nucleus accumbens. (2) Injection of 10 micrograms of morphine into habenula produced a significant increase in escape response latency 20-40 min after the injection. This antinociceptive effect of morphine was attenuated by naloxone or muscimol, and enhanced by bicuculline methochloride administered to periaqueductal grey, suggesting that morphine may act on habenula to activate a descending neural pathway extending to periaqueductal grey to induce an antinociceptive effect, which seems to utilize endogenous opioid peptides and gamma-aminobutyric acid as its mediators. Taking together, the results suggest that habenula is an important relay in the descending neural pathway from nucleus accumbens to periaqueductal grey subserving antinociception.

Sensitivity to painful and nonpainful electrocutaneous stimuli in monkeys: effects of anterolateral chordotomy

Four Macaca nemestrina monkeys were trained to pull a manipulandum to escape electrocutaneous stimulation (ES) applied to either leg. The intensities of stimulation which the monkeys chose to escape were those that humans identify as painful. The duration of escape trials was inversely related to stimulus intensity, and the force of escape responses was directly related to ES intensity. Reflexive responses were elicited by stimulus intensities below and above the escape threshold, and the force of the flexion reflexes was a negatively accelerating function of stimulus magnitude. The monkeys were also trained to respond, for water reinforcement, to cued, low-intensity ES. The stimulus intensities detected for water reinforcement were 50-100 X less than the escape thresholds. Following unilateral, anterolateral chordotomy, all monkeys demonstrated a large reduction in percentage of escape responding to stimulation of the contralateral leg. When the animals did escape contralateral stimulation, the latencies to respond were longer than preoperatively. The percentage and latency of escape responses to stimulation of the ipsilateral leg were not changed following chordotomy. Despite the depression of contralateral pain reactivity, the animals continued to respond to low levels of stimulation on the detection task, demonstrating that anterolateral chordotomy reduced the painfulness of strong stimulation without eliminating sensibility for low levels of stimulation. However, postoperative detection thresholds were consistently higher contralaterally than ipsilaterally. This effect resulted from slight contralateral decreases and significant ipsilateral increases in sensitivity to low levels of ES (relative to preoperative values). Thus, contralateral axons in the anterolateral column contribute to detection of light cutaneous stimulation, and chordotomy appears to disinhibit inputs from large myelinated afferent fibers to ipsilateral neurons in the spinal gray matter caudal to the lesion. The strictly contralateral slowing and reduction in percentage of pain reactivity by chordotomy correlated with reports from human patients. However, reflexive measures did not suffice as indicants of pain sensitivity. The chordotomies produced bilateral attenuations of reflexive amplitudes. Also, the force of operant escape responses was reduced with stimulation of either side. Thus, the disfacilitation of motoric reactions extended both rostral and caudal to the spinal lesions that interrupted propriospinal axons in the vicinity of the ventral horns.

Met-Enkephalin-Arg 6-Phe 7-like immunoreactive substances mediate electroacupuncture analgesia in the periaqueductal gray of the rabbit

The present study was undertaken to investigate whether the C-terminal extended Met-enkephalin heptapeptide (Met-enkephalin-Arg 6-Phe 7, MEAP) played a role in mediating the analgesic effect of electroacupuncture in rabbits. MEAP and its degrading enzyme inhibitor captopril as well as antiserum against MEAP were injected into the periaqueductal gray (PAG) via a previously implanted cannula. Their effects on nociception were tested by the escape response latency (ERL) elicited by radiant heat applied on the skin of the snout. (1) Microinjection of MEAP (30–240 nmol) into PAG produced a dose-dependent analgesic effect which was 2.5 times more potent than Met-enkephalin (MEK) and 3 times less potent than morphine. The complete reversal of the analgesia elicited by 240 nmol of MEAP by a small dose of naloxone (0.1 mg/kg, i.v.) indicates that the effect of MEAP is mediated by naloxone sensitive opioid receptors. (2) In rabbits, a dose-dependent analgesia was elicited by an intra-PAG injection of captopril (60–240 nmol). A single dose of 240 nmol captopril increased ERL by more than 100%. This effect could be reversed by 30 nmol of naloxone injected into the same site, or by antiserum recognizing MEAP (1 μL, titer 1:1500) but not by antiserum recognizing MEK (1 μl, 1:8000) suggesting that captopril was able to protect MEAP from degradation. (3) Intra-PAG injection of 60 nmol of captopril significantly potentiated the after effect of electroacupuncture (EA) induced analgesia. This effect could be blocked either by 30 nmol (but not 7.5 nmol) of naloxone, or by 1 μl (but not 0.1 μl) of MEAP antiserum. These results suggest that MEAP may cause analgesia by acting in PAG, and could be operative in EA analgesia.

The bed nucleus of the stria terminalis and immobilization-stress: Unit activity, escape behaviour, and gastric pathology in rats

Multiple unit-activity in the bed nucleus of the stria terminalis was increased or decreased, relative to baselines, during physical restraint in rats. Changes in unit-activity were also obtained by presenting an auditory stimulus that had been paired with the immobilization treatment. The animals escaped from that stimulus in behavioural tests, and bilateral lesions in the bed nucleus reduced the latencies of escape responses. The lesion also increased the severity of restraint-induced mucosal erosions. The latter effect was most pronounced when the damage was in the lateral portion of the bed nucleus. It was concluded that the bed nucleus of the stria terminalis is part of a coping system which responds when the organism is placed in a stressful situation.

Behavioral changes and mercury concentrations in tissues of rats exposed to mercury vapor

The present study was designed to determine critical brain mercury concentrations associated with specific behavioral changes during exposure to mercury vapor. Rats exposed to 3 mg Hg/m 3 for 3 hr, 5 days per week, for 15 to 42 weeks, showed a decline in conditioned avoidance response. The latency of escape response also increased in pole climb shock escape. The time to the onset of effects varied from 12 to 39 weeks among 14 rats exposed to mercury. All rats recovered to preexposure baseline within 12 weeks after the termination of exposure. A significantly poor behavioral performance was noticed in rats with brain mercury concentrations of approximately 20 μg Hg/g. Behavioral recovery was seen when the mercury concentrations decreased to 10 μg Hg/g brain tissue. These results suggest that the critical concentration of inorganic mercury in the brain associated with behavioral changes in the rat ranges from about 10 to 20 ppm. In spite of the high concentrations of mercury, the nervous tissues of rats with mercury vapor intoxication in this experiment were normal.

Aggressive behaviors of paired rodents in an avoidance context.

Although the number of rodents of different species and sexes was somewhat small, the consistency of the results enables a reasonably confident description of the effect of pairing rodents in an avoidance context. Considering first the situation in which both rodents were required to make the same manipulatory response to avoid or escape from electric shock: I. Naive rodents paired in this situation do not learn to avoid the shock by responding after the onset of a warning signal and before the shock. In the same situation, the rodents avoid 75-90 percent of the shocks if trained singly. This deficit is not the result of failing to notice the warning signal nor detecting its significance; the incidence of crouching, squealing and anticipatory foot-stomping indicate that the warning signal had acquired secondary aversive properties. 2. The presence of two rodents in the same avoidance situation does not materially affect their escape behavior when viewed at the molar level of the latency of escape responses. At a more molecular level, however, the escape response was almost invariably executed by the rat judged to be submissive when paired outside the avoidance context. When the shock was not quickly terminated, the dominant rat made distinct threat and aggressive responses such as foot-stomping and aborted attack until the submissive rat turned the wheel. 3. After the termination of the shock, the rodents engaged in various forms of interaction of an aggressive nature, including sparring, muzzling, over-and-under, and actual fighting. The most dramatic form observed was mounting with pelvic thrusting by the dominant rodent, even if it was a sexually naive female in the presence of another non-receptive female. 4. Essentially the same pattern of behavior was observed if either or both of the rodents had been pretrained singly in the apparatus either to escape or to avoid the shock. In the case of laboratory rats, which were observed to remain in close proximity to each other, the disappearance of avoidance behavior was more gradual than in their wild counterparts. In the case of the Florida packrats, which were observed to remain very far apart in the apparatus, avoidance behavior gradually reappeared. 5. The pairing of rodents in an avoidance situation had a dramatic effect upon their subsequent behavior when introduced into the situation singly. Even if they had previously learned the avoidance response individually, very little avoidance behavior was observed after a few sessions paired with another rodent. 6. All of the above observations are specific to the situation in which the same manipulatory response is required of both rodents. If a shuttle avoidance situation is employed,in which the necessity for confrontation in making the response is obviated, then avoidance behavior by both rodents continues when paired essentially at the same level as when run singly.

The effects of exposure to mercury vapor on behavior of rats

The exposure of rats to mercury vapor (17 mg/m 3, 2 hours a day) produces an increase in escape response latency and a decrease in avoidance responding during 30 days of mercury exposure. In addition, there was a marked increase in the duration and severity of reflexive fighting behavior; and spontaneous fighting developed. Histologic changes in the central nervous system, consisting predominantly of perivascular cuffing by lymphocytes in the medulla oblongata, were also observed.

Pressurized air: The negative factor

Normal and impaired-hearing rats were trained with a light CS in a pressurized-air shuttle-avoidance task. No differences were observed between these two groups in emotionality, number of escapes, percent learning, trials to criterion, number of avoidances and escape response latency. Results were interpreted as indicating that the tactual experience of air blast rather than the auditory experience is the primary negative quality of this US.

Effects of Fear Conditioning on Avoidance Learning

Rats were given 0, 8, 50, and 100 fear conditioning trials prior to shuttle-box avoidance learning. The fear conditioning trials resulted in: (a) an increased latency of escape responses during the initial avoidance training, (b) a greater variability of avoidance learning scores, and (c) a slight, but not statistically significant, improvement in avoidance learning. These results are attributed to fear being associated with the buzzer and to the establishing of favorable and incompatible responses to the grid shock.