Effects of pretraining compatible and incompatible responses on subsequent one-way and shuttle-avoidance performance in rats.

Conducted 6 experiments with male Holtzman rats. A single noncontingent footshock was found to facilitate subsequent one-way and shuttle avoidance if the CS in preshock and avoidance training was the same. If the to-be-established instrumental response was punished during preshock, or if Ss were required to run toward the CS paired with shock during pretraining, the facilitative effects of preshock were eliminated. Facilitation by a single preshock was not enhanced if shock was escapable, regardless of the CSs, task, or whether escape was immediate or delayed. If Ss received 10 one-way escape trials, the beneficial effects of preshock on one-way and shuttle avoidance were enhanced. In contrast, shuttle-escape training produced no such beneficial effects on avoidance performance. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of one-way and shuttle-avoidance performance of gerbils and rats.

Compared the avoidance probability of 10 male and 10 female Long-Evans rats and an equal number of gerbils in a l-way and in a shuttle task. Rats in the shuttle task, especially males, had lower avoidance probabilities than gerbils possibly reflecting a species difference in the response hierarchy in the shuttle task. It is suggested that the lower avoidance probabilities of rats may be attributable to the displacement of the flight response by other species-specific defense reactions (SSDRs) induced by the impossibility in the shuttle task of physically escaping the site of noxious stimulation. The uniformity of gerbil avoidance probability across sex and task suggests that the impossibility of fleeing the location of noxious stimuli does not alter the hierarchy of SSDRs in the gerbil. (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of variations in stimulus similarity and response requirement during pre-shock upon subsequent one-way active avoidance learning.

Describes 2 experiments with 48 adult male Holtzman albino rats, which examine further the stimulus and response conditions under which prior fear conditioning facilitates 1-way active avoidance acquisition. Fear in both experiments was established during passive avoidance training by administering a single 2-sec shock following a cross-through response from a white to a black compartment. Subsequent active avoidance acquisition was facilitated in Exp. I even though the response requirements of the 2 tasks were incompatible. In Exp. II reversed stimulus-shock arrangements existed in the 2 learning tasks. Facilitation of avoidance acquisition as a function of the prior task was again obtained. (French summary) (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in vulnerability to inescapable shock in rats.

The present study determined whether individual differences in neophobia during an open-field pretest predict vulnerability to inescapable electric shock, as measured by 2 tests of learned helplessness in rats. Shuttle-escape latencies and saccharin finickiness increased across groups that had received increasing numbers of inescapable shocks 24 hr earlier. Dispersion in the test measure as well as the percentage of variance explained by pretest neophobia were greater when no or few shocks were delivered in the interpolated stress phase. Pretest neophobia was positively related to stress vulnerability in both tests under these conditions. Further increments in stressor severity overwhelmed even the most stress-resistant rats, thereby decreasing dispersion in the test measure and eliminating the predictive value of pretest neophobia. This pattern of outcomes was more robust for the shuttle-escape measure of helplessness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Potentiation, overshadowing, and prior exposure to inescapable shock.

Four experiments are reported which explore the possibility that prior exposure to inescapable shock alters the way in which animals process information from responding during subsequent escape training. The stimulus consequences of responding were manipulated in each experiment. Rats received escapable shock, yoked, inescapable shock, or no shock prior to fixed ratio-2 (FR-2) shuttle escape training. A novel change in illumination following each shuttle response had opposite effects on inescapably shocked and control subjects. It dramatically improved the performance of inescapably shocked rats but impaired the performance of restrained subjects. The signal had no effect on escape trained animals. Response-produced auditory cues following each lever press on an FR-3 lever-press escape task were also observed to improve learning in inescapably shocked rats but to impair learning in restrained controls. The relation between lever pressing and the exteroceptive cue was manipulated. The exteroceptive cue enhanced learning in inescapably shocked rats when any two of the three required lever presses produced the cue. In contrast, the performance of restrained animals was impaired whenever the third response of the FR-3 produced the cue. Otherwise performance was unimpaired. The implications of these results are discussed with respect to the phenomena of potentiation and overshadowing, as well as to ways in which prior exposure to inescapable shock might alter information processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitative and disruptive effects of prior exposure to shock on subsequent avoidance performance.

Subjected 40 male rats from each of 5 strains to 10 signaled inescapable 1-ma shock presentations. Shock facilitated subsequent 1-way and shuttle-avoidance performance (1-ma shock) in Charles River hooded, Wistar, Holtzman, and Sasco Ss, but did not significantly affect avoidance learning in Sprague-Dawley Ss. A 2nd experiment employing 120 male Holtzman rats indicated that inescapable shock of 1 ma. facilitated subsequent 1-way and shuttle-avoidance performance, while exposure to shock of 2 ma. facilitated 1-way and interfered with shuttle-avoidance performance. Movement ratings recorded during both CS and intershock intervals in pretraining were found to be good predictors of subsequent avoidance performance in preshocked Ss. Results are interpreted in terms of response repertoire changes produced by shock in conjunction with the defense reaction necessary in acquiring the avoidance response. (22 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure to learn to escape in rats previously exposed to inescapable shock depends on nature of escape response.

Results of previous studies show that dogs exposed to inescapable shocks in a Pavlov harness subsequently fail to learn to escape shock in a shuttle box. The present 6 experiments attempted to replicate this finding with male Sprague-Dawley rats (N = 182). In agreement with many previous investigations, Exp I found that Ss exposed to inescapable shock did not fail to learn to escape in a shuttle box. Exp II, III, and IV varied the number, intensity, and temporal interval between inescapable shocks and did not find failure to learn in the shuttle box. An analysis of responding in the shuttle box revealed that Ss shuttled rapidly from the very 1st trial, whereas dogs acquire shuttling more gradually. Exp V and VI revealed that Ss exposed to inescapable shock failed to learn to escape when the escape response was one that was acquired more gradually. Exp V utilized a double crossing of the shuttle box as the escape response and Exp VI utilized a wheel-turn response. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of sensory restriction upon responses to cortical stimulation in rats.

Assigned 43 Long-Evans hooded rats to 7 groups receiving normal, visually restricted, or auditory restricted rearing experience. Ss were then implanted with bipolar pairs of electrodes in the auditory and visual projection areas. Electrical stimulation of the cortex was used as a discriminative stimulus for a lever-pressing response. The ease of using electrical stimulation of visual or auditory cortex as a discriminative stimulus was related to Ss' paranatal sensory experience. Deleterious effects were limited to the restricted cortical projection area, and there were suggestions of facilitated performance in response to stimulation of the nonrestricted cortical areas. These effects were absent when restriction was induced in adulthood. (28 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of naltrexone and signaling inescapable electric shock on nociception and gastric lesions in rats.

Two experiments, with 144 male Long-Evans hooded rats, examined the antinociceptive effects of signaled shock and its physiological underpinnings. In Exp I, Ss were exposed to 1 of 3 shock conditions: no shock, unsignaled shock, and signaled (by a 10-sec, 1,000-Hz tone) shock. In each condition, Ss were tested hourly in the absence of tones for nociception, with vocalization to shock used as the behavioral measure. Ss receiving signaled shocks had stomach ulcer scores intermediate between those of no-shock and unsignaled shock Ss. Signaled-shock Ss also displayed a pronounced vocalization antinociception effect. This suggested that signaled shock may be less aversive. Exp II investigated a possible role of endogenous opiate peptides in these effects. Ss received hourly injections of either the opiate antagonist naltrexone (7 mg/kg, ip) or saline. There were no significant effects of naltrexone on either stomach pathology or nociception scores. The same effects of signaled shock were obtained as in Exp I. It is concluded that the role of endogenous opiates in the effects of signaled shock seen here is minimal. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ventromedial septal lesions in rats reduce the effects of inescapable shock on escape performance and analgesia.

In 2 experiments with 104 male Sprague-Dawley rats, lesions of the ventromedial septum (VMS) reduced or eliminated several effects of exposure to inescapable shock, but lesions of the dorsolateral septum did not. Exp I demonstrated that VMS lesions reduced the loss in body weight produced by inescapable shock and eliminated the subsequent (24 hrs later) interference with escape performance (learned helplessness). Exp II demonstrated that VMS lesions reduced the analgesia that occurs immediately following inescapable shock and the analgesia reinstated by exposure to escapable shock 24 hrs later. Findings indicate that VMS lesions reduce several responses to inescapable shock and suggest the possibility that all of these effects may reflect a unitary deficit. It is hypothesized that VMS lesions reduce these effects of exposure to inescapable shock either by reducing the ability of the rats to learn that their responses and shocks were uncorrelated or by reducing the emotional impact of this lack of correlation. (52 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stress and adenosine: II. Adenosine analogs mimic the effect of inescapable shock on shuttle-escape performance in rats.

Examined, in 3 experiments involving 208 male rats, the role of adenosine regulation in escape deficits produced by earlier exposure to inescapable shock in rats (learned helplessness). Adenosine analogs injected before escape testing mimicked the effect of earlier inescapable shock, with the magnitude of the deficit varying with dose and drug specificity for A? adenosine receptors. Agonist-induced and stress-induced escape deficits were eliminated by pretest treatment with the centrally acting adenosine receptor antagonist theophylline but not the peripheral antagonist 8-[p-sulfophenyl]-theophylline. Finally, preexposure to an ineffective number of inescapable shocks interacted in synergy with an ineffective pretest injection of adenosine agonist to maximize deficits in escape performance. These data implicate energy regulation and a central compensatory action by adenosine in the aspects of helplessness related to onservation–withdrawal. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Opiate antagonists and long-term analgesic reaction induced by inescapable shock in rats.

Five experiments with 240 male albino rats examined the influence of opiate antagonists (naltrexone; 1–24 mg/kg, ip) on both the short-term analgesic reaction resulting 30 min after exposure to inescapable shock and the long-term analgesic reaction resulting after reexposure to shock 24 hrs after inescapable shock exposure. Exp I showed that the long-term analgesic reaction could be reduced by administration of naltrexone prior to exposure to inescapable tail shock. Exp II showed that the reduction in the long-term analgesic reaction produced by naltrexone was dose-dependent. Exp III showed that the long-term analgesic reaction could also be reduced by administration of naltrexone prior to reexposure to shock. Exp IV showed that the long-term analgesic reaction could be reduced by administration of a large dose of naloxone prior to reexposure to shock. Exp V showed that the short-term analgesic reaction was reduced by naltrexone administered prior to inescapable shock. Implications for the biochemical substrates of both learned helplessness and stress-induced analgesia are discussed. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Facilitative and disruptive effects of prior exposure to shock on subsequent avoidance performance": Erratum.

Reports an error in "Facilitative and disruptive effects of prior exposure to shock on subsequent avoidance performance" by H. Anisman and T. Waller (Journal of Comparative and Physiological Psychology, 1972[Jan], Vol 78[1], 113-122). On page 114, the sentence beginning on Line 56, Column 2, should read: "Thirty seconds after placement in the compartment one half of the rats were given 10 CS (light and tone) presentations in which the CS was 9 sec. in duration, while the remaining rats received 10 CS-US presentations in which the US was a 1-ma. shock (constant current, ac) 2 sec. in duration." (The following abstract of this article originally appeared in record 1972-22565-001.) Subjected 40 male rats from each of 5 strains to 10 signaled inescapable 1-ma shock presentations. Shock facilitated subsequent 1-way and shuttle-avoidance performance (1-ma shock) in Charles River hooded, Wistar, Holtzman, and Sasco Ss, but did not significantly affect avoidance learning in Sprague-Dawley Ss. A 2nd experiment employing 120 male Holtzman rats indicated that inescapable shock of 1 ma. facilitated subsequent 1-way and shuttle-avoidance performance, while exposure to shock of 2 ma. facilitated 1-way and interfered with shuttle-avoidance performance. Movement ratings recorded during both CS and intershock intervals in pretraining were found to be good predictors of subsequent avoidance performance in preshocked Ss. Results are interpreted in terms of response repertoire changes produced by shock in conjunction with the defense reaction necessary in acquiring the avoidance response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of activity and immobility conditioning upon subsequent heart-rate conditioning in curarized rats.

Assigned 40 female Long-Evans hooded rats to experimental or yoked-control groups receiving activity conditioning in a running wheel or immobility conditioning in a small open field. Following 10 days under these procedures, all Ss were curarized and punished either for the emission of high or low heart rates. The pretraining procedures contributed significantly more to the heart-rate changes observed under curare than did the reinforcement contingencies imposed under this latter condition. Implications are discussed with respect to the specificity of operant cardiovascular conditioning and the general issue of somatocardiovascular relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Catecholamine depletion in mice upon reexposure to stress: Mediation of the escape deficits produced by inescapable shock.

Reports 9 experiments with 372 male Swiss-Webster mice in which, immediately following exposure to 60 inescapable shocks, Ss had significantly reduced hypothalamic norepinephrine (NE). Within 24 hrs NE levels returned to control values. Reexposure to as few as 10 shocks 24 hrs after initial stress exposure resulted in significant decline of NE. At this interval after shock, escape performance was severely disrupted, with a large proportion of Ss exhibiting numerous failures to escape shock. Increasing brain dopamine (DA) and NE by levodopa treatment prior to shock prevented the escape deficits. Conversely, pairing 5 inescapable shocks with NE depletion by FLA-63, or both DA and NE depletion by alpha-methylparatyrosine, disrupted escape performance 24 hrs later. Residual drug effects, state dependence, or sustained amine turnover could not account for the behavioral changes. Data are discussed in terms of catecholamine mediation of escape performance through variations in response maintenance abilities. It is suggested that long-term effects of inescapable shock may be due to sensitization effects or conditioned amine depletion. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of signaling inescapable shock on subsequent escape learning: Implications for theories of coping and "learned helplessness."

The present experiments reveal that shuttle-escape performance deficits are eliminated when exteroceptive cues are paired with inescapable shock. Experiment 1 indicated that, as in instrumental control, a signal following inescapable shock eliminated later escape performance deficits. Subsequent experiments revealed that both forward and backward pairings between signals and inescapable shock attenuated performance deficits. However, the data also suggest that the impact of these temporal relations may be modulated by qualitative aspects of the cues because the effects of these relations depended upon whether an increase or decrease in illumination (Experiment 2) or a compound auditory cue (Experiment 4) was used. Preliminary evidence suggests that the ability of illumination cues to block escape learning deficits may be related to their ability to reduce contextual fear (Experiment 3). The implications of these data for conceptions of instrumental control and the role of fear in the etiology of effects of inescapable shock exposure are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of instructor-delivered sequential evaluative feedback upon student's subsequent classroom-related performance and instructor ratings.

128 college students were randomly assigned to 1 of 4 instructor-delivered evaluative feedback conditions (uniformly positive, uniformly negative, negative-to-positive, or positive-to-negative). Expectations for subsequent performance were effectively manipulated by false evaluative feedback. Ss then listened to an audiotaped lecture, after which they took an exam on the lecture (the performance measure). Finally, Ss rated the instructor who gave the audiotaped lecture. The instructor-delivered evaluative feedback manipulation had a significant effect on the Ss' performance and ratings of the instructor, such that performance was better and ratings of the instructor were higher in the uniformly positive condition, followed, respectively, by the negative-to-positive, positive-to-negative, and uniformly negative conditions. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fear conditioned with escapable and inescapable shock: Effects of a feedback stimulus.

Four experiments, with 140 male Fischer rats, compared the level of fear conditioned with escapable and inescapable shock. In Exps I and II, master Ss that had received 50 unsignaled escapable shocks were less afraid of the situation where the shock had occurred than were yoked Ss that had received inescapable shocks. Comparable results were found in Exps III and IV, which used freezing as an index of fear of a discrete CS that had been paired with shock. Control per se was not necessary to produce the low level of fear seen in the master Ss. Yoked groups receiving a feedback signal at the time the master made an escape response showed a low level of fear that was comparable to that of the masters and significantly less than that seen in the yoked Ss without feedback. In addition, there were strong suggestions that control and feedback exert their effects through the same or highly similar mechanisms. Possible explanations for how control and the exteroceptive feedback signal produce this effect are discussed. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure to learn to escape by rats previously exposed to inescapable shock is partly produced by associative interference.

2 experiments demonstrated that the effects of prior exposure to inescapable shock on the subsequent acquisition of an escape response in rats is determined by the nature of the contingency that exists between responding and shock termination during the escape learning task, and not by the amount of effort required to make the response or the amount of shock that the S is forced to receive during each trial. Exp I, using 48 male Simonsen rats, showed that inescapably shocked Ss did not learn to escape shock in a shuttle box if 2 crossings of the shuttle box were required (fixed ratio, FR, -2) to terminate shock, but did learn this FR-2 response if a brief interruption of shock occurs after the 1st crossing of the FR-2. Exp II with 72 Ss showed that inescapably shocked Ss learned a single-crossing escape response as rapidly as did controls, but were severely retarded if a brief delay in shock termination was arranged to follow the response. Results are discussed in terms of the learned helplessness hypothesis, which assumes that prior exposure to inescapable shock results in associative interference. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of prenatal exposure to cocaine on Morris water maze performance in adult rats.

The spatial memory of adult rats prenatally exposed to cocaine and that of control offspring was assessed using the Morris water maze. Offspring were derived from Sprague Dawley dams that received subcutaneous injection of 40 mg/kg/3 cc cocaine hydrochloride (C40) daily on gestational Days 8-20, pair-fed dams injected with saline, or nontreated control dams. After acquisition, the platform was moved to a new location (reversal phase). Probe trials were conducted at the end of acquisition and reversal training. On the 1st acquisition day, adult male and female offspring prenatally exposed to cocaine required significantly more time and traversed a greater distance to find the hidden platform than did control offspring. Despite these initial differences observed in C40 offspring performance, all of the rats were performing at equivalent levels at the time probe trials were conducted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)