Genetic differences in avoidance learning by Rattus norvegicus: Escape/avoidance responding, sensitivity to electric shock, discrimination learning, and open-field behavior.

Studied the behaviors of Long-Evans rats selectively bred for either good (SHA line) or poor (SLA line) shuttle box avoidance learning. The results of Exp I indicated that the phenotypic difference in avoidance learning was not associated with differences in speed of escape or avoidance responding. Differences between the lines in frequency of intertrial responses (ITRs), which appeared during training but not during pretest, suggest that ITRs in Ss of the low-avoidance SLA line were more suppressed by electric shock than in Ss of the high-avoidance SHA line. This result suggests that SLA Ss may be more emotionally responsive than SHA Ss. Exp II demonstrated that the Ss of the 2 lines did not differ in absolute sensitivity to electric shock, and Exp III showed that the poor performance of the SLA line was not due to an inability to learn. Ss also provided evidence that the poor avoidance learning by SLA Ss was due to their emotional reactivity. Observations of open-field behavior in Exp IV were consistent with this hypothesis. It is concluded that the major consistent correlate of the phenotypic difference in avoidance learning was greater emotionality or emotional reactivity in SLA than in SHA Ss. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects on avoidance performance of vagal stimulation during previous fear conditioning in rats.

Attempted to determine, from experiments on 5 groups of 10 male albino rats each, whether parasympathetic stimulation given coincidentally with electric shock in a fear-conditioning situation would alter later performance on an avoidance conditioning task. 10 Ss were implanted with a small chronic electrode around the cervical vagus. During preconditioning, consisting of 8 trials of tone followed by inescapable shock, 1 group of Ss received stimulation of the vagus at the time foot shock was delivered. During subsequent avoidance conditioning, these Ss performed the avoidance task significantly better than Ss that received the same preconditioning without vagal stimulation and as well as Ss that had received no preconditioning shock trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of olfactory bulbectomy and DSP4 treatment in avoidance learning in the rat.

In 3 experiments with 101 male Sprague-Dawley rats, olfactory bulbectomized Ss and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4)-treated Ss were studied on a 2-way active avoidance task as well as on step-down passive avoidance and fear conditioning and retention tasks. The DSP4-treated, but not olfactory bulbectomized, Ss were impaired in acquiring 2-way avoidance; bulbectomized, but not DSP4-treated, Ss showed notable passive avoidance and fear retention deficits. Bulbectomized Ss treated with DSP4 did not show passive avoidance and fear retention deficits, nor did these Ss evidence the 2-way avoidance impairment of the DSP4-treated Ss. No alteration of dopamine-beta-hydroxylase activity in the frontal cortex and hippocampus as a result of the bulbectomy operation was indicated. The double dissociation between bulbectomized and DSP4-treated Ss is discussed in terms of opponent behavioral processes, influenced by olfactory bulbectomy and DSP4, which may permit insights into experimental investigations of stress, anxiety, and depression. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of graduated exposure with feedback of exposure times on snake phobias.

In an experiment with 17 female and 3 male snake-phobic Ss (selected from a group of 900 applicants using interview data and results of the Fear Survey Schedule III and the Snake Fear Questionnaire), the S-controlled graduated exposure of a snake with feedback of exposure times resulted in significantly less avoidance behaviors for snake-phobic Ss than for control snake-phobic Ss who did not receive therapy. The therapy did not result in significantly less reported feelings of fear immediately after therapy for the therapy Ss. Both avoidance behaviors and self-reports of fear were significantly less for the therapy Ss than for control Ss when the Ss were given generalization tests 1 mo after the termination of therapy in 1 nonlaboratory situation (a zoo) and 4 laboratory situations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Running-wheel avoidance behavior following septal area lesions in rats.

Studied acquisition of a running-wheel avoidance response in 52 male Wistar rats with (a) septal lesions, (b) septal and postcommissural fornix lesions, or (c) septal, postcommissural fornix, and anterior thalamic damage. Ss with lesions confined to the septum were deficient in acquiring the avoidance response compared with both normal Ss and Ss with the more posterior lesions. Ss sustaining combined septal-fornical and septal-fornical-thalamic lesions did not differ from normal Ss or from each other in their acquisition scores. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Faster acquisition of discriminated lever-press avoidance by hippocampectomized rats.

Reports that 10 male albino rats with bilateral hippocampal destruction produced by aspiration acquired a discriminated lever-press avoidance task faster than, and exhibited avoidance levels consistently superior to 10 unoperated Ss and 10 Ss with neocortical destruction. Destruction of the hippocampus in Ss with extensive previous experience on the task resulted in improved avoidance performance, but the improvement was not significantly superior to the performance of controls. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some behavioral effects of olfactory bulb damage in the rat.

Conducted 5 experiments in which male Holtzman rats (N = 50) with either olfactory bulb or septal lesions were tested on position-habit reversal, nonappetitive passive-avoidance, 1-way avoidance, and 2-way avoidance tasks. Ss with septal damage exhibited the expected behavioral abnormalities on all tasks. Ss with bulbar damage were deficient on 1-way avoidance, were facilitated on 2-way avoidance, and could not be distinguished from the normal Ss on the other 2 tasks. (20 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of hippocampal lesions on the rat's reaction to a cat.

Confronted 20 male albino rats with a cat in a circular runway. Ss with hippocampal lesions displayed lower levels of freezing than did operated controls. When avoidance or escape was possible, Ss with lesions showed superior cat avoidance and less freezing in the intervals between cat approaches. The similarity of reactions to a cat and to conditioned threat stimuli in Ss with hippocampal damage suggests that the effects of hippocampal damage in aversive conditioning tasks may be largely mediated by an alteration of innate freezing reactions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Group training in goldfish (Carasius auratus): Effects on acquisition and retention.

2 experiments with a total of 656 goldfish investigated the effects of group training on acquisition and retention. Ss in groups acquired an active avoidance task more readily than individually trained Ss. Unreinforced retention testing showed that individual Ss had in fact acquired the avoidance response. The addition of trained "leader" Ss to groups did not enhance acquisition performance but somewhat impeded it. It is proposed that it is the presence per se of other fish that in some manner facilitates acquisition in groups of fish and that leader-follower interactions do not account for the observed effect. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrabox and extrabox cues in avoidance responding: Effect of septal lesions.

Reports an experiment with 126 male albino rats, 48 of whom received bilateral septal lesions. A combination of conflicting intrabox and extrabox cues was necessary to produce deficient acquisition of 2-way avoidance responding relative to 1-way responding in normal Ss. Septal lesions impaired 1-way avoidance acquisition by delaying the 1st avoidance response. In 2-way acquisition, the faster acquisition of septal Ss may be attributable either to an inability to inhibit responding or to an inability to utilize certain types of cues. Until the effects of septal lesions upon the ability to process olfactory and spatial information have been determined, disinhibitory interpretations of changes in avoidance responding must be held in question. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Corticosterone levels during avoidance learning in rats with cingulate lesions suggest an instrumental reinforcement deficit.

Studied changes in fear or arousal during 2-way avoidance learning in male Moll-Wistar rats with cingulate lesions. The 12 Ss with lesions restricted to the cingulum bundle and rostral one-third to one-half of the cingulate cortex exhibited no deficit compared with the 15 operated control Ss in the acquisition of 2-way active avoidance. However, the cingulate-lesioned Ss did not exhibit the increase in intertrial sniffing and grooming or the decline in plasma corticosterone levels to the degree observed in control Ss in the course of acquisition and stabilization of the avoidance response. The primary effect of this lesion may therefore be less effective reinforcement of the instrumental response. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Fornix lesions, plasma ACTH levels, and shuttle box avoidance in rats.

In Exp I, which used 90 male hooded rats as Ss, the consequences of fornix lesions (FLs) for partial acquisition, and performance at 3 postacquisition time intervals, of shuttlebox avoidance were tested. FL Ss achieved criterion performance more rapidly than controls. The performance of controls was depressed when they were tested 1 hr after acquisition ("Kamin effect"), but the performance of FL Ss was not impaired. The possibility that FLs altered plasma ACTH concentrations at the intervals after avoidance training used in Exp I was examined in Exp II (96 Ss). Plasma ACTH concentrations were elevated in FL Ss compared with unoperated and sham-operated controls, both immediately and 1 hr after avoidance training. Plasma ACTH levels were not elevated in FL Ss following either stress alone or 24 hrs after avoidance training. Results indicate that FLs cause elevated ACTH levels in rats after avoidance training that are responsible for elimination of the Kamin effect. In addition, data support the contention that enhanced acquisition of 2-way active avoidance by rats with FLs or hippocampal damage might be attributable to increased plasma ACTH levels. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interaction of tail-pressure stress and d-amphetamine in disruption of the rat's ability to ignore an irrelevant stimulus.

48 male Sprague-Dawley rats received either 0 or 30 preexposures to a tone that was later used as a warning stimulus in a 2-way active avoidance task. Consistent with previous data, tone preexposure resulted in retarded acquisition of the conditioned avoidance response (CAR) in saline-control Ss and in Ss that received chronic administration of dextroamphetamine (DAM; 1 mg/kg, sc). Ss that received tail-pressure stress prior to stimulus preexposure also showed retarded acquisition of the CAR. However, Ss that received a combination of tail pressure and DAM did not show retarded CAR acquisiton following stimulus preexposure. Results suggest an interaction between environmental stressors and DAM in producing attentional deficits. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian analysis of avoidance conditioning in the goldfish (Carassius auratus).

Conducted 2 experiments in which 144 and 54 goldfish, respectively, were trained in a shuttlebox with light as CS and brief shock as UCS. Performance was measured in terms of "initial response" to the CS (at least 1 crossing of the hurdle on any trial) and-where the CS was not terminated by the initial response-in terms of "multiple response" to the CS (more than 1 crossing on any trial). The level of initial responding was as high in classically conditioned Ss (shocked on every trial) as in avoidance Ss, whether or not the CS was terminated by response, but lower in control Ss, yoked with the avoidance Ss, and lower also in punished Ss (shocked only if they responded). Multiple responding was negligible in avoidance Ss, but common in classically conditioned and in punished Ss. Results can be accounted for in purely Pavlovian terms, no reference to instrumental learning being required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sidman avoidance performance and response suppression in rats with septal lesions.

Ran 10 male Long-Evans hooded rats with septal lesions on 3 Sidman avoidance schedules which differed only in length of response-shock (RS) interval. Of the 5 septal Ss run on postoperative acquisition, all emitted responses at lower rates than the 5 controls, maintained shock rates equivalent to those of controls, and distributed their responses more efficiently than controls. Successive reductions in length of the RS interval produced suppression of avoidance responding in all Ss. However, for septal Ss, more sessions and a shorter RS interval were required to suppress avoidance responding. Performance of 5 Ss given preoperative experience was not changed by septal ablation. Both the lower response rate and the difficulty in suppressing avoidance responding are interpreted in terms of a deficit related to acquisition of stimulus control by conditioned aversive stimuli. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preoperative differential housing and dorsal hippocampal lesions in rats.

The resemblance between the effects of social isolation and of hippocampal lesions (HCLs) in rats led to a study that investigated whether rats socially isolated at weaning rather than grouped counterparts show less behavioral change after sustaining dorsal HCLs when adults. Ss were 8 grouped male Lister rats with HCLs, 8 grouped male controls, 8 isolated male with HCLs, and 8 isolated controls. In socially reared Ss, HCLs produced increased ambulation and object contact in an open field, reduced passive avoidance in a runway task, and produced faster acquisition of active avoidance in a shuttlebox, but there were no such differences in isolation-reared Ss. Ambulation and object contact in isolates were intermediate to those of HCL Ss and intact group-housed Ss, and the behavior of isolates during passive and active avoidance training was generally similar to that of grouped Ss with HCLs. The introduction of a distractor during approach training in an alley reduced running speeds more in Ss with HCLs than in controls. The significant interactions between housing and lesion state suggest that neural pathways associated with the hippocampal formation may mediate some behavioral effects of differential housing. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hormonal dissociation of limbic lesion effects on shuttle box avoidance in rats.

In a study with a total of 57 male albino Holtzman-derived rats, Ss with septal or hippocampal lesions showed facilitated acquisition of a shuttle box avoidance response compared to normal controls. Ss with septal lesions were also highly resistant to extinction compared with normal Ss. When the same lesion effects were examined in hypophysectomized Ss, the Ss with septal lesions continued to show facilitated performance, and Ss with hippocampal lesions performed no differently than nonoperated controls. These findings are consistent with the hypothesis that the facilitated avoidance performance found in rats with hippocampal lesions is attributable to lesion-induced changes in hypophyseal activity, but similar changes induced by septal lesions are not. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Disruption of passive avoidance learning in the rat by electrical stimulation of the hippocampus.

Five experiments, with 184 male albino rats, examined the effect of electrical stimulation to discrete regions of the dorsal hippocampus on passive avoidance. Ss stepped from a brightly lit, white compartment to a dark compartment. Following footshock in the dark compartment, step-through latencies were recorded 1 min, 24 hrs, and 48 hrs after footshock. When given 20 step-through trials prior to footshock, dentate-stimulated Ss exhibited lack of passive avoidance with particularly short latencies at 1 min, and CA1-stimulated Ss showed reduced latencies compared with latencies of cortical and nonoperated controls. In Exp II, Ss given stimulation in the same regions performed the avoidance task without prior step-through experience. All groups showed less passive avoidance than the control group in Exp I, and there were no significant differences between groups. With a single step-through trial before the footshock trial, longer avoidance latencies were recorded, but again groups did not differ significantly. Dentate-implanted Ss, given 20 prior exposure trials but with stimulation at different stages of the task sequence, demonstrated a passive avoidance deficit at 1 min after footshock. Results are discussed in terms of the generation of expectancy that the black compartment was a safe place and the effects of brain stimulation on the expectancy, with particular reference to O. S. Vinogradova's (1975) theory of hippocampal function. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bait-shyness acquisition is impaired by VMH lesions that produce obesity.

Lesioned Carworth CFE female rats in the area of the ventromedial nucleus of the hypothalamus (VMH) before or after avoidance learning. Prelesioned Ss learned to avoid familiar saccharin-sweetened water associated with apomorphine less rapidly, and during extinction lost the avoidance more rapidly than controls. Ss lesioned after avoidance learning continued to avoid, and during extinction lost the avoidance at the same rate as controls. When given ad-lib food and water, lesioned Ss became obese. 1 tentative interpretation is that VMH-lesioned rats overrespond to environmental stimuli, including their food. This interferes with gustatory-visceral associations needed for satiety and bait-shyness acquisition. Another possibility is that overresponding to environmental stimuli and impaired gustatory-visceral associations are both direct consequences of VMH lesions. (32 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of response restriction during exposure to inescapable shock upon subsequent one-way and shuttle-avoidance performance in rats.

Investigated the effects of signaled inescapable shock on subsequent avoidance performance in 3 experiments with male Holtzman rats (N = 188). Exp I indicated that prior shock exposure (PSE) facilitated 1-way and shuttle avoidance. When Ss were preshocked in a harness so that free mobility was not possible, the facilitative effects of PSE on shuttle, but not 1-way avoidance performance, were largely reduced. Exp II indicated that activity during CS periods following PSE was greater among unrestrained than restrained Ss. Exp III showed that immobilization via injection of succinylcholine chloride did not affect the facilitative effects of PSE relative to that of Ss preshocked in a harness. Results are interpreted in terms of response repertoire changes produced by PSE in conjunction with the response requirement of the avoidance task. (French summary) (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)