Tonic immobility in the blue crab (Callinectes sapidus, Rathbun): Its relation to threat of predation.

Investigated the tonic immobility response in the blue crab in a series of 7 experiments, using a total of 209 blue crabs. Although reported to be a powerful variable in other species, preinduction electric shock produced inconsistent increases in the duration of tonic immobility with the Ss. Manipulations that were more directly relevant to the fear of predation had considerably greater effects than shock. Physical damage to the chelipeds, mirror image stimulation, and immobilization beneath artificial glass eyes all produced significant prolongation of the immobility episode. Ss immobilized on a bed of sand rather than on a hard surface showed shorter immobility durations, suggesting that opportunity for escape is an important variable affecting the immobility reaction. Results support the contention that threat of predation is the organizing principle behind tonic immobility. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cholinergic modulation of tonic immobility in the rabbit (Oryctolagus cuniculus).

Conducted a study with 13 adult Dutch Belt rabbits to determine the effects of the anticholinergic agent scopolamine and the cholinergic agent physostigmine on tonic immobility in rabbits. Recordings of the EEG activity from cortex and hippocampus were also made before, during, and after each test session. Scopolamine significantly prolonged the response and produced large amplitude slow wave activity in the EEG of both cortex and hippocampus. Physostigmine significantly shortened the duration of immobility and increased rhythmic slow activity in the frequency range of 5.5-9.1 Hz in the hippocampus while producing a desynchronized cortical rhythm. It is suggested that the cortex and hippocampus play a role in modulating tonic immobility duration by inhibiting the brain-stem structures thought to control this response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dopaminergic and cholinergic influences on motor behavior in chickens.

Examined the effects and interactions of apomorphine (AP; 0–4.0 mg/kg, ip), haloperidol (HAL; 0–2.0 mg/kg, ip), scopolamine (SCO; 0–2.0 mg/kg, ip), and pilocarpine (PIL; 0–50 mg/kg, ip) on stabilimeter activity and tonic immobility in White Leghorn?×?Black Australorp male chickens. The dopamine receptor agonist AP enhanced motor activity and decreased the duration of tonic immobility behavior in a dose-dependent manner. HAL, a dopamine receptor antagonist, increased the duration of tonic immobility and attenuated AP-induced increase in activity. Motor activity could also be increased by the cholinergic antagonist SCO. In addition SCO decreased the duration of tonic immobility. On the other hand, the cholinergic agonist PIL increased tonic immobility behavior and decreased SCO's effect on motor activity. Studies of the interaction of dopaminergic and cholinergic systems showed that HAL could attenuate the activity-stimulating effects of SCO, whereas PIL had a similar, but lesser, effect on AP-induced activity. Results support the suggestion that in birds, as in mammals, the dopaminergic and cholinergic systems are intimately involved in the expression of motor behavior. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal ablation prolongs immobility response in rabbits (Oryctolagus cuniculus).

Hypothesized that damage to the hippocampus would reduce tonic immobility in rabbits. 2 measures were used with 14 implanted and 6 control Dutch Belt rabbits: the number of successful inductions of tonic immobility in a test session and the duration of each successful immobilization. Both of these measures increased in Ss with hippocampal lesions rather than decreased as expected. It is suggested that the hippocampus may act to suppress any ongoing dominant or prepotent response, whether the response involves movement or cessation of movement. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tonic immobility in chickens: Possible involvement of monoamines.

In 4 experiments with a total of 259 Production Red chickens, it was found that tonic immobility was affected by a variety of drugs that act on monoaminergic systems. Compounds that enhanced the duration of tonic immobility were dextro-LSD, 2-bromo-dextro-lysergic acid (BOL-148), pargyline, and iproniazid; no effect was found when Ss were given 5-hydroxytryptophan, para-chlorophenylalanine, or atropine. Injections of serotonin depressed response duration. A suggestive parallel was noted between the results of the present study and those of previous work reporting drug-induced suppression of raphe electrical activity. The data implicate monoamines, especially serotonin, in the mediation of behavioral activation and suppression. (48 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

p-Chloroamphetamine: Effects on tonic immobility, activity, and temperature in chickens.

The effects of parachloroamphetamine (PCA) on tonic immobility (TI) duration, activity, and temperature in 216 Production Red chickens were examined in 6 experiments. 10 or 15 mg/kg PCA ip produced a significant attenuation of TI duration. Involvement of norepinephrine or dopamine in this effect was considered questionable, since catecholamine synthesis inhibition with alpha-methylparatyrosine did not alter PCA attenuation of TI duration. However, serotonin synthesis inhibition with parachlorophenylalanine produced a blockade of the PCA effect on TI when Ss were tested 60 min after PCA. A competing response interpretation of the PCA effect in terms of enhanced motor activity was ruled out, since, in contrast to the hyperactivity observed in mammals, PCA produced a decrease in both open-field and stabilimeter activity. A PCA-induced decreased in core temperature was observed in Exp VI. Together with previous findings, results suggest a mammalian–avian reversal in drug effects. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Internal inclusions in brown eggs: relationships with fearfulness and stress

Tonic immobility reaction and heterophil: lymphocyte ratio (indices of fearfulness and stress, respectively) were studied in hens laying eggs with or without internal inclusions (blood and meat spots). Two brown egg Spanish breed of chickens were used. There were no significant differences between groups in terms of tonic immobility duration. Birds of the group with internal inclusions appeared to be less fearful when defined by the number of inductions to achieve tonic immobility (1.4+/-0.1 vs 1.1+/-0.1; P < 0.01). Tonic immobility duration was significantly shorter in the group of hens with internal inclusions, when only those laying the abnormal egg the day before measurement of tonic immobility were included in this group (264+/-33 vs 395+/-30 s; P < 0.01). There was a significant difference in the heterophil:lymphocyte ratio between the two groups of hens (P < 0.01), mean value being significantly higher in the group with internal inclusions (0.43+/-0.02) than in the control group (0.33+/-0.02). Hens that laid eggs with internal inclusions had significant heterophilia (P < 0.01). Differences were consistent across the breeds. The incidence of internal inclusions was significantly greater (P < 0.001) in eggs with pink shells (an abnormality associated with the effect of stress). The results suggest that the laying of eggs with internal inclusions involves changes in fearfulness and stressfulness of hens.     

Effect of administration of adrenalin on immobility reaction in domestic fowl.

Results of 2 experiments with White Leghorn chicks (N = 49) lend support to the hypothesis that tonic immobility is mediated by fear. In Exp. I, Ss injected subcutaneously with adrenalin remained immobile for a significantly greater duration than Ss injected subcutaneously with physiological saline. In Exp. II, it was found that a subcutaneous injection of adrenalin both facilitated the onset and maintained the duration of the immobility reaction in nonsusceptible Ss which previously showed no immobility. An injection of physiological saline neither facilitated nor maintained the immobility reaction in a control group of nonsusceptible Ss. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Immobility and supination in garter snakes (Thamnophis elegans) following handling by human predators.

A common response of animals to physical restraint is tonic immobility. The authors observed the behavior of garter snakes, Thamnophis elegans, in the field to determine the frequency of immobility as a response to handling. Most snakes fled after release, but the remainder remained immobile, sometimes on their backs (supination), for up to 10 min. Immobility was seen most often in pregnant snakes, which also were more likely than other snakes not to have moved before capture. Failure to move, either before or after capture, might be a consequence of the limited locomotory ability of gravid snakes. However, the lack of observations of interactions between snakes and their natural predators impedes researchers' understanding of the antipredator value, if any, of tonic immobility. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Habituation and tonic immobility in domestic chickens

The habituation of tonic immobility in chickens was examined in six studies. It was shown that repeated elicitation of immobility, and not just handling, was responsible for reduced response durations after multiple exposures to manual restraint. Habituation was a function of the number of stimulus presentations and, in addition, proved surprisingly durable, with diminished reactions using lasting at least 2.5 mo. Strain differences were found in the number of trials required to reach a criteria of habituation, and habituation proceeded faster when immobility termination was self-paced as opposed to experimenter induced. Also, massed trials produced robust sensitization effects rather than diminished responsiveness.     

Rearing influences on tonic immobility in three-day-old chicks (Gallus gallus).

Subjected 86 3-day-old White Leghorn chicks, reared either socially or in isolation in large or small boxes, to tonic immobility by a ventral restraint induction procedure. Test boxes were identical to rearing boxes or differed only in size. Incidence and duration of immobility were reliably enhanced by social and high-density rearing, but similarity of test and rearing boxes had no effect. A high negative correlation between vocalization rate and duration of eye closure was obtained. Results are discussed in terms of the optimizing induction procedure in relation to early righting behavior. Qualitatively different stages of immobility are defined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of conditioned fear on tonic immobility in domestic chickens.

Conducted 2 conditioned fear experiments with 36 and 14 Production Red chickens. Ss given brief exposure to a compound stimulus which had been previously paired with intense electric shock remained immobile significantly longer following manual restraint than Ss which received either shock only or the compound stimulus only during training. The administration of a tranquilizer (metoserpate hydrochloride, pacitran) reduced the effect of conditioned fear on the resulting duration of immobility. Results provide strong support for the notion that fear underlies the tonic immobility reaction in domestic fowl. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Strain differences among chickens in tonic immobility: evidence for an emotionality component

Substantial strain differences in tonic immobility were found between different breeds of chickens. Crossbreeding between strains showing different immobility durations yielded hybrids that exhibited intermediate reactions. For purpose of relating the strain differences in tonic immobility to more conventional measures of emotionality, data were collected on open-field activity, defecation, and adrenal weight. Overall, the results implicated strain-specific differences in emotionality as being the basis for the observed differences in immobility. Latency to defecate in an open field, however, was highly correlated with latency to ambulate. It was argued that defecation, rather than being an absolute measure of fear or emotionality, may in fact be an intermediate response to gradual fear reduction.     

"Scared Stiff": Catatonia as an Evolutionary-Based Fear Response.

Catatonia, long viewed as a motor disorder, may be better understood as a fear response, akin to the animal defense strategy tonic immobility (after G. G. Gallup & J. D. Maser, 1977). This proposal, consistent with K. L. Kahlbaum's (1874/1973) original conception, is based on similarities between catatonia and tonic immobility ("death feint") as well as evidence that catatonia is associated with anxiety and agitated depression and responds dramatically to benzodiazepines. It is argued that catatonia originally derived from ancestral encounters with carnivores whose predatory instincts were triggered by movement but is now inappropriately expressed in very different modern threat situations. Found in a wide range of psychiatric and serious medical conditions, catatonia may represent a common "end state" response to feelings of imminent doom and can serve as a template to understand other psychiatric disorders. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Animal hypnosis: Factual status of a fictional concept.

Notes that animal hypnosis, or tonic immobility, is an easily induced and readily quantifiable phenomenon found in many different species. Recent findings on the behavioral, ecological, chemical, neurological, genetic, and ontogenetic aspects of animal hypnosis are reviewd in light of current and historical interpretations. The response seems to be quite sensitive to manipulations designed to affect fear. In terms of adaptive significance, the reaction can be modified through selective breeding, and both naturalistic as well as laboratory investigations bolster the thesis that tonic immobility may participate in the ecology of predator-prey relationships. (93 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Conditioned inhibition and tonic immobility: Stimulus control of an innate fear response in the chicken.

Investigated the role of Pavlovian contingencies in modifying the tonic immobility reaction (IR) of Production Red chickens (N = 62) in 2 experiments. In Exp. I, Ss which received a stimulus associated with shock onset (CS1) showed facilitated duration of and increased susceptibility to IR compared with Ss which received a cue paired with shock offset (CS2). However, the lack of difference between Ss receiving CS1 and Ss receiving no stimulation, and the relatively low duration of IR, implied that CS2 training could mask the effects of conditioned fear. Exp. II provided an independent assessment of the relative strengths of CS1 and CS2. The former stimulus was shown to potentiate and the latter to actively inhibit IR. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A central cholinergic inhibitory system as a basis for tonic immobility (animal hypnosis) in chickens.

4 experiments provided support for the hypothesis that tonic immobility (TI) in chickens, which may be analogous to response suppression in the rat, is a result of fear and is mediated by central cholinergic systems. A total of 124 experimental and 54 control, White Leghorn cockerel chicks were the Ss. Exp I established that scopolamine, a central and peripheral acting anticholinergic, will reduce the duration of TI, whereas methylscopolamine, which acts only peripherally, will not. Exp II established a dose-response curve for scopolamine and TI. Exp III demonstrated that scopolamine increased activity and that this increase may be a factor in reducing the duration of TI. Exp IV showed that physostigmine, which blocks acetylcholinesterase and allows longer action of acetylcholine at the synapse, increased the duration of TI. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Posttraining norepinephrine infusion into the central amygdala differentially enhances later retention in Roman high-avoidance and low-avoidance rats.

Memory-enhancement effects of norepinephrine (NE) were investigated by infusing NE into the central amygdala (CEA) of Roman high-avoidance (RHA) and low-avoidance (RLA) rats after training on active and passive behaviors in the defensive-burying paradigm. During acquisition, both lines spent comparable time in burying behavior. RLA rats, but not RHA rats, also displayed substantial immobility. During retention, the CSF-treated RLA rats mostly displayed immobility to the nonelectrified probe, whereas the RHA rats showed neither burying nor immobility. In the RLA rats, high-dose (200 ng), but not low-dose (20 ng), NE infusion enhanced the duration of the passive response (immobility) without affecting the active response. NE given into the CEA of RHA rats caused a selective dose-dependent appearance of the active behavioral component. The results suggest a phenotype-dependent effect of intra-amygdaloid NE on memory processes in the rat. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tonic immobility in chickens (Gallus gallus): Shock-termination thresholds.

Examined the effects of electric shock on the disruption of tonic immobility (TI) in 82 straight-run Production Red chickens in 3 experiments. Shock-termination thresholds were highly consistent, reliable, and easily measured. The intensity of shock needed to terminate TI rarely exceeded 0.5 mA and morphine (1 mg/kg) had no effect on shock termination thresholds. In contrast, electric shock delivered prior to immobility onset reliably raised shock-termination thresholds. It is concluded that shock-termination thresholds may represent a useful means of indexing the depth of an immobility episode. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversiveness of the induction of tonic immobility in chickens (Gallus gallus).

Notes that, because of its sensitivity to various manipulations associated with either increases or decreases in aversive stimulation, tonic immobility seems to qualify as a fear reaction. The present experiments provided an independent assessment of the aversive properties of immobility induction. In Exp I, using 32 Production Red day-old chickens, a cue previously paired with onset of immobility suppressed activity in a stabilimeter. Similarly, in Exp II, with 24 Production Red day-old chickens, response-contingent immobilization produced punishmentlike effects in an instrumental conditioning paradigm. Taken together, results support the notion that the physical restraint involved in immobility induction is an aversive event. (PsycINFO Database Record (c) 2010 APA, all rights reserved)