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)     

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)     

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)     

Tryptophan and tonic immobility in chickens: Effects of dietary and systemic manipulations.

Consistent with a serotonergic-midbrain raphe model of tonic immobility, 4 experiments designed to evoke changes in serum tryptophan produced reliable effects on the duration of the response in a total of 114 Production Red chickens. Systemic injections of tryptophan, the dietary precursor of serotonin, led to a dose-dependent increase in immobility, with optimal effects observed within 30 min after injection. Dietary depletion of endogenous tryptophan attenuated the duration of immobility, and a diet completely free of tryptophan, but supplemented with niacin, practically abolished the reaction. Dietary replacement of tryptophan reinstated the response. In a 5th experiment with 20 Ss, tryptamine, an alternative metabolic by-product of tryptophan, had no effect on immobility. Data are discussed in light of evidence showing serotonergic involvement in tonic immobility. (22 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)     

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)     

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)     

Induction of eating in newly hatched chicks.

Conducted 3 experiments to investigate stimulus factors in the induction of eating and pecking in 128 newly hatched chickens. In Exp I, a combination of preexposure to a pecking-induction stimulus and the movement of that stimulus had eating-inducing properties equivalent to those of exposure to a flock of free-feeding birds. Exp II confirmed and refined that result, but also demonstrated that the placement and direction of the inducer stimulus was of considerable importance. Exp III showed that food reinforcement was not a necessary condition for the induction and maintenance of pecking. It is concluded that (a) the presence of appropriate stimulation is a partial explanation of social facilitation effects in eating and (b) pecking induction can be considered a distinct behavioral phenomenon. (37 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Rat (Rattus norvegicus) defensive behavior in total darkness: Risk-assessment function of defensive burying.

Although rats (Rattus norvegicus) spend much of their lives in the darkness of burrows, defensive behavior in the dark has rarely been studied. We compared rats' reactions to aversive stimuli in dark and lighted 2-alley, burrowlike environments. Exp 1 assessed reactions to an unsignaled airblast; Exp 2 assessed neophobic reactions to an unfamiliar steel ball. Half of the rats were tested in light and half, in total darkness. In both experiments rats directed defensive burying and stretched approach toward the aversive stimulus. Darkness increased airblast-induced burying behavior but not burying behavior toward the unfamiliar object; it had no effect on stretched-approach behavior in either experiment. Because the location and nature of the aversive stimulus was ambiguous in Exp 1 but not in Exp 2, these results support the hypothesis that risk assessment is one function of defensive-burying behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fear and affiliation in domesticated male rats.

Male rats actively seek the opportunity to interact with other male rats. Three experiments with 208 Long-Evans males examined the hypothesis that the presence of conspecifics can reduce the behavioral signs of fear and that this capacity provides part of the attraction to conspecifics. In Exp I, the immobility response was measured following exposure to a stressful noise. Ss that were observed in groups exhibited shorter durations of immobility than those observed alone. The "group" effect was sufficiently powerful to nullify different housing conditions and different degrees of familiarity among the Ss. Exp II compared social and nonsocial stimuli and found that only the former effectively reduced the immobility response. In Exp III, stressed Ss were more likely to choose to interact with a conspecific in a T-maze than were nonstressed Ss. Again, rearing conditions made little difference; both individually and group housed Ss were highly attracted to a conspecific. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste avoidance, but not aversion, learning in rats lacking gustatory cortex.

Control rats rapidly learned to avoid drinking either a sucrose solution (Exp 1) or an NaCl solution (Exp 2) when the taste was paired with illness. These rats also produced aversive reactivity to each of these solutions in a taste reactivity test. Rats that lacked gustatory cortex (GC) learned to avoid drinking sucrose and NaCl, albeit at a slower rate than control rats. GC rats failed to display aversive reactivity to these tastes. The GC rats did show normal aversive reactivity to a strong quinine HCl solution during additional tests. It is suggested that the avoidance developed by GC rats did not entail a palatability shift of the conditional stimulus as it did in control rats. This altered learning strategy may account for the consistent learning deficits found in GC rats trained to avoid tastes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serological and bacteriological observations on experimental infection with Salmonella hadar in chickens

Over the past 3 years the frequency of Salmonella hadar infections has increased in Belgium in both poultry and humans. Therefore, the course of infection with S. hadar in poultry was investigated. One day-old and 4 week-old specific pathogen-free chickens were orally infected with one of two S. hadar strains, SH1 or SH2. Mortality was 6% (SH1) and 17% (SH2) in birds infected at 1 day-old. Chickens infected at 1 day-old with SH2 showed a mild diarrhoea. The S. hadar faecal excretion in birds infected at 1 day-old remained high throughout the experiment until 12 weeks post-inoculation (pi). Faecal excretion was lower in older birds. Antibodies to S. hadar were observed from 2 weeks pi (SH2, infected at 1 day-old) or 4 weeks pi (SH1, both groups; SH2, chickens infected at 4 weeks of age). The percentage of chickens with antibodies was higher after infection at 1 day-old than after infection at 4 weeks of age. In a second experiment 1 day-old chicks were infected with SH1 and autopsied at regular intervals until 42 days pi. SH1 was isolated from the caeca from 3 h pi onwards and from the liver and spleen from 18 h until 14 days pi. Serous typhlitis and omphalitis were the main lesions. The number of macrophages in the lamina propria of the caecal tonsils was slightly increased from 18 h until 2 weeks pi. In the liver, inflammation was observed in the portal triads and in the sinusoids. This study indicates that infections with S. hadar lead to intense colonisation of the gut and extensive faecal shedding. It may also cause invasive infections in 1 day-old chickens.     

The parabrachial nucleus is essential for acquisition of a conditioned odor aversion in rats.

Rats with bilateral ibotenic acid lesions of the gustatory zone of the parabrachial nuclei (PBN) failed to acquire a conditioned taste aversion (CTA) in Exp 1. They also failed to acquire a conditioned odor aversion (COA) when the olfactory cue was presented on an odor disk in Exp 2 or when it was presented in water in Exp 3. The failure to acquire the COA was not due to an inability to detect or use olfactory stimuli because the lesioned rats displayed neophobia to a novel odor in Exp 3 and used an olfactory cue to predict the availability of an aversive capsaicin solution in Exp 4. Together, the results demonstrate that, as with CTA learning, PBN cell bodies are essential for the establishment of a specific association between an olfactory conditioned stimulus and a lithium chloride unconditioned stimulus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Human blink startle during aversive and nonaversive Pavlovian conditioning.

Potentiation of blink startle during aversive and nonaversive Pavlovian single-cue conditioning was assessed in human Ss. In Exp 1 (N?=?89), the conditioning group received paired presentations of a visual CS and an unconditioned stimulus/stimuli (UCS), whereas the control group was presented with a random sequence. The UCS was an electric shock for half the Ss and a nonaversive reaction time (RT) task for the other half. Electrodermal conditioning was evident regardless of the nature of the UCS, but blink potentiation was found only in the conditioning group that had been trained with the aversive UCS. These results were replicated in Exp 2 (N?=?65), in which a nonaversive UCS of increased motivational significance was used. Thus, only aversive conditioning seems to affect the affective valence of the CS, at least as reflected by changes in a skeletal reflex. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learned aversions to copulatory behaviors in male rats.

Used LiCl for an aversive effect on copulatory behavior in adult experienced and inexperienced male hooded rats (Exp I) and in inexperienced adult male Holtzman rats (Exp II). When males received an injection of LiCl immediately after an encounter with an estrous female, the vigor of subsequent copulatory responding was initially unaffected. After 5–20 such pairings, however, males displayed an aversion to copulatory behaviors; they ceased to copulate entirely. These aversions persisted when Ss were tested in a novel environment and extinguished after 4 nonreinforced trials. This multiple-trial adaptation of the conditioned taste aversion paradigm provides a new approach to the aversive control of sexual behavior. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian aversive context conditioning using carbon dioxide as the unconditional stimulus.

Four experiments were conducted to examine the utility of carbon dioxide (CO?) as an aversive unconditioned stimulus/stimuli (UCS) in a Pavlovian context conditioning paradigm. Exp 1 demonstrated that rats exposed to CO? in a distinctive context showed elevated levels of freezing relative to controls. Exp 2 replicated this basic effect with a modified conditioning procedure and additionally demonstrated conditioned analgesia. Exp 3 demonstrated a positive monotonic relationship between UCS duration and resistance to extinction of freezing behavior as well as conditioned analgesia. Exp 4 demonstrated extinction and an extinction-related phenomenon, renewal. These studies clearly demonstrate the utility of CO? as a Pavlovian UCS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Taste reactivity as a dependent measure of the rapid formation of conditioned taste aversion: A tool for the neural analysis of taste-visceral associations.

Investigated the ability of animals to form taste aversions following neural manipulations. In Exp 1, 10 rats received intraoral infusions of sucrose every 5 min starting immediately after the injection of LiCl. 12 controls were injected with NaCl. Oromotor and somatic taste reactivity behaviors were videotaped and analyzed. Lithium-injected Ss decreased their ingestive taste reactivity over time; aversive behavior increased. Controls maintained high levels of ingestive responding and demonstrated virtually no aversive behavior following sodium injection. Ss were tested several days later for a conditioned taste aversion (CTA). Rats previously injected with lithium demonstrated significantly more aversive behavior than controls. Exp 3 revealed that when similarly treated rats were tested for a CTA while in a lithium-induced state, difference in the ingestive behavior was observed. In Exp 2, naive rats were injected with NaCl or LiCl but did not receive their 1st sucrose infusion for 20 min. Ss also received infusions at 25 and 30 min postinjection. There were no differences in the task reactivity behavior displayed. Rats dramatically changed their oromotor responses to sucrose during the period following LiCl administration, provided the infusions started immediately after injection, a change attributable to associative processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Guilty by mere association: Evaluative conditioning and the spreading attitude effect.

Five experiments investigated the phenomenon that attitude formation is not confined to the co-occurrence of an attitudinal object with an evaluated experience. The pairing of a target with a (dis)liked person not only affects the evaluation of the previously neutral person but spreads to other individuals who are (pre)associated with the target (spreading attitude effect). Exps 1 and 2 provided evidence for the spreading attitude effect in appetitive as well as aversive evaluative conditioning. Exp 3 showed that the spreading attitude effect is a robust phenomenon resistant to extinction. Exp 4 demonstrated that attitude spread can be transferred to 2nd-order conditioning. Finally, Exp 5 supports the notion that the spreading attitude effect is not dependent on cognitive resources. Implications for social as well as applied psychology are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Putting the brakes on prejudice: On the development and operation of cues for control.

A model concerning the establishment and operation of cues for control was developed and tested to understand how control can be exerted over (automatic) prejudiced responses. Cues for control are stimuli that are associated with prejudiced responses and the aversive consequences of those responses (e.g., guilt). In Exp 1 and 2, 3 events critical to the establishment of cues occurred: behavioral inhibition, the experience of guilt, and retrospective reflection. In Exp 3, the presentation of already-established cues for control did, as expected, produce behavioral inhibition. In Exp 4, participants were provided with an experience in which cues could be established. Later presentation of those cues in a different task resulted in behavioral inhibition and less racially biased responses. (PsycINFO Database Record (c) 2010 APA, all rights reserved)