Avoidance Decrement Research Articles

The role of learning and stress in predator avoidance of hatchery-reared coho salmon ( Oncorhynchus kisutch) juveniles

The possibility of conditioning hatchery-reared coho salmon ( Oncorhynchus kisutch) juveniles to avoid predation, and the role of learning and stress in predator avoidance was investigated under controlled laboratory conditions. When coho that had survived predation (experienced) by lingcod ( Ophiodon elongatus) were mixed with equal numbers of naive coho and exposed to predation, experienced fish consistently survived in greater numbers than did naive ones. When examined separately, experienced coho were able to avoid predation longer than naive coho. Coho exposed to stimuli associated with predation for two, 15-min bouts were better able to avoid capture by lingcod than naive fish, demonstrating that learning may play a major role in the development of predator avoidance. Salmon raised in the psychosensory-deprived environment of hatcheries appear to suffer from a decrement in predator avoidance which may be readily improved with conditioning. Coho stressed by handling showed a decreased ability to avoid predators, but recovered from this effect in 90 min.

Developmental effects of early postnatal treatment of rats with prochlorperazine

This study examined effects of neonatal prochlorperazine in rats tested as adults in a variety of behaviors. The drug exposure impaired open field behavior during treatment neonatally. However, no differences in open field behavior were observed in adulthood. Adult females that had received drug were less efficient in obtaining food reinforcement in a conditioned maze performance than were respective controls and showed a slight increase in motor activity during accommodation. d-Amphetamine-induced motor activity was greater in both treated males and females relative to respective controls. Spaced trials in shuttle-box avoidance uncovered an avoidance decrement in the treated females only. This drug treatment appears to cause subtle changes in brain development in the rat.

The actions of dopaminergic and noradrenergic antagonists on conditioned avoidance responses in intact and 6-hydroxydopamine-treated rats.

The actions of various doses of haloperidol, pimozide, clozapine, and phenoxybenzamine were assessed on a conditioned-avoidance response (CAR) in control and 6-hydroxydopamine-treated rats, using a pole-climbing device. Haloperidol proved to be the most potent in disrupting the CAR. Pimozide was about 1.6 times less potent, and clozapine and phenoxybenzamine were approximately 52 and 155 times less potent than haloperidol, respectively. Prior treatment with 6-hydroxydopamine slightly enhanced the sensitivity to some of the doses of the DA and NE antagonists. Significantly lower levels of responding, however, were observed only after the highest dose of primozide. Clonidine was not only ineffective in reverting avoidance decrements, but also induced a further decline of the CAR. Apomorphine produced a partial, but significant, reversal of the haloperidol and pimozide-induced depression of conditioned responses. Regarding the clozapine-pretreated animals, a significant antagonism was observed only with the smaller dose of apomorphine. The highest dose induced a further decline of the CAR. The DA agonist was also ineffective in the phenoxybenzamine-injected rats. Amphetamine was effective in antagonizing the avoidance decrements produced by all the CA antagonists. Our results support the suggestion that CAR depends on both DA and NE mechanisms. DA seems to be more significant that NE, however, since the CAR was more depressed when receptors depending on the former neurotransmitter were blocked.

Retention of Avoidance: Time since Original Training or Time since Shock

4 groups of 9 Holtzman rats were run on a brightness discrimination task in a T-maze under the conditions of shock-train-shock-retest or transfer. Under like manipulation intervals of 1 hr. or 24 hr. between shock-train and shock-retest or transfer and with constant 24-hr. intervals between train-shock, there was no decrement in avoidance for the 1-hr. retest group nor an increment for the 24-hr. transfer group. This supports memory retrieval rather than behavioral inhibition.

Differential effects of intraventricular administration of 6-hydroxydopamine on behavior of rats in approach and avoidance procedures: Reversal of avoidance decrements by diazepam

The administration of 6-hydroxydopamine (6-HD) and pargyline to rats produced similar selective in responding during the conditioned stimulus (CS) on a discriminated avoidance test where the unconditioned stimulus (US) was shock and on an analogous conditioned approach test where the US was water. Approach behavior during the CS generally recovered, however, while avoidance decrements in the same rats remained for the duration of testing. This suggested that 6-HD-induced avoidance decrement was a result of two independent but interacting processes: (1) a decrease in conditioned behavior as reflected by the similar decrease in responding on both tests; and (2) a hyper-reaction to aversive stimuli that resulted in a tendency to selectively suppress avoidance behavior after the animal received shock. In support of this hypothesis, it was found that 6-HD-induced avoidance decrements could be reversed (1) by treatment with diazepam, a drug that releases suppressed responses; or (2) by delaying avoidance testing until conditioned responding had recovered, thus minimizing the interaction of the two processes.

6-hydroxydopamine and avoidance: Possible role of response suppression

The intraventricular administration of 6-HD to rats pretreated with pargyline resulted in sever, long-lasting decreases in avoidance responding with little or no effect on escape responding. Despite the fact that the rats failed to avoid, they appeared to be able to discriminate the CS, as was evident from freezing behavior and other symptoms of an apparent fear reaction during the CS. The increase in freezing, a response that was incompatible with avoidance was seen during the first few test sessions after 6-HD treatment and seemed to be largely responsible for a gradual decline in avoidance responding during this same period. The role of CA depletion in the animal's response to aversive stimuli thus appears to be a significant aspect of the avoidance decrement that follows 6-HD administration.

Modification of avoidance behavior in 6-hydroxydopamine-treated rats by stimulation of central noradrenergic and dopaminergic receptors

Rats showing reliable decrements in conditioned avoidance behavior after the intraventricular administration of 6-hydroxydopamine (6-HD) with pargyline pretreatment were given various dopaminergic and noradrenergic agonists. Intraventricular injections of DA or L-NE or intraperitoneal injections of apomorphine or L-DOPA reversed the avoidance decrements, often restoring performance to pre-6-HD-treatment levels. Furthermore, these agonists all produced behavior characteristic of activity in dopaminergic neurons. Clonidine, a noradrenergic agonist, also reversed avoidance decrements, but did not produce behavior characteristic of stimulation of dopaminergic neurons in the brain. Pretreatment with spiroperidol, a dopaminergic receptor blocker, prevented the recovery induced by all agonists, although clonidine-induced recovery was affected least. The results are discussed in terms of possible separate roles for dopaminergic and noradrenergic neurons in the brain in avoidance behavior.

The effects of Δ9-tetrahydrocannabinol upon fear-motivated behavior in squirrel monkeys

The present study investigated the effects of three doses (4.0, 8.0, 12.0 mg/kg) of Δ9-tetrahydrocannabinol (THC) upon the behavior of six squirrel monkeys subjected to a Sidman nondiscriminated avoidance schedule that superimposed conditioned stimuli (CS)—unavoidable shock pairings upon the ongoing avoidance behavior. All the animals demonstrated facilitated avoidance response rates and general motor activity during the aversive CS. Oral administration of THC produced avoidance decrements with a consequent increase in the number of shocks received only under the highest dosage (i.e., 12.0 mg/kg). All doses of THC reduced the facilitation of avoidance response rates normally noted during the aversive CS and severely reduced general motor activity. These results were interpreted to suggest that THC may reduce the level of fear normally generated during the presentation of an aversive CS previously associated with unavoidable shock.

Avoidance decrement as a function of training-test interval: Single cycle or multiphasic?

Y-maze avoidance performance was assessed in independent groups of rats during a 50-trial test session which followed a 30-trial training session by 15 min, 1, 6, 12, 18, 24 or 30 hr. While a decrement in avoidance performance was present at the 1 hr interval, there was no evidence for a difference among the other groups. The number of correct discriminations was unaffected by training-test interval.

An analysis of d-amphetamine produced facilitation of avoidance acquisition in rats and performance changes subsequent to drug termination

In Experiment I rats were trained on a discriminated Y-maze active avoidance task following administration of saline or one of three dosages (.75, 1.50 or 3.0 mg/kg) of d-amphetamine. The six measures recorded simultaneously during each session indicated that the avoidance facilitation produced by d-amphetamine was due to attenuation of shock-induced behavioral suppression resulting in a behavioral baseline more compatible with the animal's associating running with shock avoidance. Results from Experiment II showed that the avoidance decrement following drug termination is dependent on training dosage and whether the drug is abruptly or gradually withdrawn. This experiment further suggested that the disruption is due to dissociation between the drug and non-drug states and could be attenuated by gradually withdrawing the drug over training sessions.

Permanent facilitation of avoidance behavior by d-amphetamine and scopolamine.

Scopolamine (0.3, 0.6, 1.2, 2.4, 4.8 mg/kg) or d-amphetamine (0.25, 0.50, 1.00, 2.00, 4.00 mg/kg) was administered daily to independent groups of rats 30 min prior to training in a discriminated, Y-maze avoidance task. A dose-dependent relationship was found between amount of avoidance facilitation and drug dosage. Discontinuation of the drug following asymptotic performance resulted in a decrement in avoidance which varied as a function of the acquisition dosage. Results from a second experiment using the same task indicated that gradually reducing the dosage on consecutive training days rather than abruptly discontinuing the drug was more effective in producing permanent avoidance facilitation in the non-drug condition.

The effect of sleep altering environments upon the acquisition and retention of a conditioned avoidance response in the rat

The presence of severely restricted environmental conditions reported to produce marked alterations in sleep patterns, most notably REM sleep, had no effect upon the acquisition and the consolidation of a conditioned avoidance response in rats. However, those subjects who learned the response in the severely restricted environment showed a marked decrement in avoidance responding when retested from normal conditions. The reestablishment of the severely restricted environment was a sufficient condition for the return of performance during retest situations. Other environments produced no such effects. The correlation between changes in sleep behavior and performance was greater than the correlation between environment and performance. There is some factor (or factors) present in such environmental situations that manifests itself in two ways: external changes in sleep patterns and the development of a factor performance coupling. It is not known whether both phenomena share a common origin or whether they are independent events. The development of an environmental state dependency provides one possible explanation for some of the behavioral alterations seen following sleep-cycle disruption. The utilization of other techniques capable of influencing sleep is necessary to determine the factors relevant, in this environment, to the production of the changes noted.

The group desensitization of children's snake phobias using vicarious and contact desensitization procedures

The effectiveness of vicarious and contact desensitization procedures for the group treatment of snake-avoidant children was investigated. Forty-four pre-adolescent boys and girls served as Ss. Vicarious desensitization children observed E and five peer models engage in gradually bolder interactions with a tame 4 ft Gopher snake. Contact desensitization subjects not only observed E and peers perform as in the foregoing conditions but also had opportunities for physical contact with model-therapists and the phobic object. Treatment consisted of two 35 min sessions for both conditions. Performance on a behavioral avoidance test was used to measure treatment effects. The following predicted results were obtained: (a) contact desensitization yielded significantly greater reductions in avoidance than did vicarious desensitization; (b) both desensitization groups demonstrated significantly larger avoidance decrements than did non-treated controls. During post-testing, 80 per cent of the children receiving contact desensitization, 53.3 per cent of those in the vicarious desensitization condition and none of the control children successfully completed the stringent terminal task of the avoidance test.

Discriminated Sidman avoidance behavior by guinea pigs

Three guinea pigs learned to postpone signalled electric shocks by pressing a bar. Although bar holding served to postpone shocks, the animals, unlike rats, did not bar-hold indefinitely. There was evidence of “avoidance decrement” in that shock densities increased with training, but this was not accompanied by a comparable decrease in response rate.

Avoidance learning in fish after fear conditioning under chloretone

Goldfish were paralyzed with chloretone during fear conditioning in an attempt to eliminate the development of responses which would be incompatible with shuttling during later avoidance training. This group showed no decrement in avoidance responding while a group which was fear conditioned without chloretone showed the expected decrement. The data would seem to support the incompatible response hypothesis.

Two Failures to Prevent Avoidance Decrement

Two experiments were performed in attempts to prevent avoidance decrement (disappearance of an initially learned avoidance response with continued acquisition training). In Exp. 1, widely distributed practice appeared to lower initial performance but did not otherwise prevent the decrement. In Exp. 2, the decrement was found with weak shock, strong shock, and with pulsed strong shock.

Role of freezing and fear in avoidance decrements following mammillothalamic tractotomy in cat: I. Two-way avoidance behavior

In experiment 1, six cats were trained in a two-way conditioned avoidance response (CAR) and then received lesions aimed at the mammillothalamic tracts (MTT). Avoidance decrements following MTT lesions were not related to changes in freezing behavior. In experiment 2, four cats were trained in the CAR and then given intensive fear conditioning (pairing of buzzer and unavoidable foot shock). On subsequent CAR test sessions, avoidance latencies for trials on which the buzzer was added were significantly (p <.01) shorter than on trials without the buzzer. Thus, a stimulus (the buzzer) capable of eliciting fear and freezing much stronger than that seen following MTT lesions actually facilitated the CAR (reduced avoidance latencies). This and the results of experiment 1 do not support the hypothesis that avoidance decrements following MTT lesions are attributable to increased fear or freezing.

Role of freezing and fear in avoidance decrements following mammillothalamic tractotomy in cat: II. Appetitively motivated behavior

Although previous work (Krieckhaus, 1964a; Krieckhaus & Chi, 1966) suggests that it is unlikely that the avoidance decrements following lesions of the mammillothalamic tract (MTT) are attributable to increased freezing behavior, in each case evaluation of freezing was confounded with concomitant changes in avoidance behavior. In the present experiment, freezing following MTT lesions was evaluated independently of avoidance behavior by using either the conditioned emotional response (CER) or an appetitively motivated visual discrimination in which the incorrect response was punished. In neither case was there any indication of increases in freezing or other signs of fear following lesions of the MTT. We thus conclude that the reported increases in freezing behavior following MTT lesions are a result of rather than a cause of a primary decrement in avoidance behavior.

Effects of punishment on avoidance decrement.

Effects of punishment on avoidance decrement.

Strain differences in avoidance learning

Twenty-four Tryon rats, 14 S1 and 10 S3, were given 100 trials in a wheel turn avoidance apparatus. In addition, 3 Ss of each strain were run for 9 more days. The S1 strain showed significantly superior avoidance performance initially and maintained this superiority on subsequent sessions. No evidence of avoidance decrement was found for either strain. These results were interpreted as being consistent with both a CER and a neural perseveration-consolidation explanation.