One-way avoidance behavior and septal lesions in the rat.

Compared 73 male Holtzman rats with septal lesions with 36 sham-operated and 41 unoperated controls on the acquisition of a 1-way avoidance response under several different stimulus and procedural conditions. Ss with septal damage were deficient in acquiring the avoidance response under several 1-way avoidance conditions involving an auditory CS, could not be distinguished from the controls in 2 experiments not involving auditory cues, and were superior to them in both a 2-way avoidance task and a conflictful 1-way avoidance task. (25 ref) (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)     

Free-operant avoidance behavior in rats with lateral septal lesions: Effect of shock intensity

The purpose of experiment 1 was to examine the relationship between shock intensity and normal rats' free-operant (Sidman) avoidance performance on a 3-component, multiple schedule. The results showed an inverted U-shaped relation between response rate and shock intensity, but no consistent relation between shock rate and shock intensity was found. Experiment 2 showed that lateral sptal lesions produced a bidirectional change in reactivity to electric shock. An increased reactivity was observed in the initial sessions starting on the 11th day after the surgery, while a reduced reactivity was observed in the final sessions when stable performance had been reacquired. These changes were not a function of the waning of general hyperreactivity with post-operative recovery: the septal lesions in this study did not produce any "sham rage". From 40 to 80% of the variance in response rates was accounted for by this bidirectional change in the reactivity to shock.     

Lowered response to postingestive cues following septal lesions in rats.

Conducted 3 experiments with a total of 36 male albino Sprague-Dawley rats and 54 male albino Carworth CFE rats. Ss with septal lesions were tested in a variety of consummatory situations (e.g., solution intake, direct stomach loads preceding pellet intake, and stomach preloads preceding glucose intake). The lesions resulted in exaggerated responding to taste factors and a decrease in responsivity to postingestive cues relative to control Ss. Results support the view that the septum is an important link in the feeding circuit. (15 ref) (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)     

Hippocampal lesions impair retention of discriminative responding based on energy state cues.

The present research investigated the hypothesis that the hippocampus is involved with the control of appetitive behavior by interoceptive “hunger” and “satiety” signals. Rats were trained to solve a food deprivation intensity discrimination problem in which stimuli produced by 0-hr and 24-hr food deprivation served as discriminative cues for the delivery of sucrose pellets. For Group 0+, sucrose pellets were delivered at the conclusion of each 4-min session that took place under 0-hr food deprivation, whereas no pellets were delivered during sessions that took place when the rats had been food deprived for 24 hr. Group 24+ received the reverse discriminative contingency (i.e., they received sucrose pellets under 24-hr but not under 0-hr food deprivation). When asymptotic discrimination performance was achieved (indexed by greater incidence of food magazine approach behavior on reinforced compared with nonreinforced sessions), half of the rats in each group received hippocampal lesions, and the remaining rats in each group were designated as sham- or nonlesioned controls. Following recovery from surgery, food deprivation discrimination performance was compared for lesioned and control rats in both Groups 0+ and 24+. Discriminative responding was impaired for rats with hippocampal lesions relative to their controls. This impairment was based largely on elevated responding to nonreinforced food deprivation cues. In addition, hippocampal damage was associated with increased body weight under conditions of ad libitum feeding. The results suggest that the inhibition of appetitive behavior by energy state signals may depend, in part, on the hippocampus. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactive effects of training condition and septal lesions on perseverative responding in the rat.

In a study with 30 male Wistar rats, Ss that had received septal lesions either prior to acquisition of a position habit (Group SAR) or immediately after position habit acquisition (Group SR) were tested on 2 reversals of the task. Compared with control-operated Ss, both groups of Ss with septal lesions exhibited position-habit reversal deficits. The 2 groups with septal lesions could not be distinguished in terms of the total number of errors made during reversal learning, but could be distinguished on the basis of the type of error committed. Compared with Group SR, Group SAR made significantly more perseverative errors on the 1st reversal and significantly fewer perseverative errors on the 2nd reversal. Group SR made significantly more nonperseverative errors than Group SAR on both reversals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of pituitary-adrenocortical system in mediating avoidance behavior of rats with septal lesions.

3 experiments with a total of 186 male Sprague-Dawley rats examined the hypothesis that the effects of septal lesions and systemic injections of scopolamine on avoidance acquisition could be attributed to the effects of either of these treatments on ACTH secretion. Septal lesions and scopolamine facilitated 2-way conditioned avoidance response acquisition, and the lesions retarded passive avoidance acquisition. However, neither the injections of dexamethasone, a synthetic glucocorticoid which inhibited ACTH secretion as did septal lesions, nor injections of ACTH which mimicked the facilitatory effects of scopolamine on basal ACTH secretion, affected avoidance in these paradigms. Thus, the main hypothesis was not supported. The finding that scopolamine did not affect passive avoidance indicates that a cholinergic system may not be involved in mediating the suppressive effects of punishment. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Suppressive and enhancing effects of footshock on food-reinforced operant responding following septal lesions in rats.

Measured effect of septal lesions on suppression of an intermittently food-reinforced lever press by contingent and noncontingent footshock, using a total of 48 experimentally naive male hooded Lister rats in 2 experiments. Ss with septal damage maintained higher response rates than did intact Ss under both contingent and noncontingent shock. Furthermore, the difference in suppression produced by the contingent and noncontingent conditions was approximately the same for the experimental Ss and controls. In Exp II performance was measured during counter-conditioning in which the correlation between contingent shock and positive reinforcement was varied. Ss with septal lesions responded at higher rates than did controls. When only reinforced responses were punished, this lesion-induced elevation represented an increase above baseline performance without punishment. This finding suggests that the effect of septal damage on appetitive instrumental performance cannot be due solely to a deficit in response inhibition. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differentiation of escape and avoidance responding in rats.

Examined escape and avoidance performance in 144 female Holtzman albino rats by factorially arranging immediate or postponed CS and UCS termination with shuttle or bar-press escape and avoidance responses. High levels of avoidance responding occurred only when the shuttle response (running) was both the escape and avoidance response, perhaps reflecting that rats are prepared to run but contraprepared to bar press when threatened by aversive stimulation. In addition, postponed UCS termination reduced avoidance performance drastically while CS termination conditions were without effect. Measures of UCS duration and clock terminations also indicated that immediate UCS termination was superior to postponed termination but additionally showed that this was so because postponed termination seriously impaired escape behavior. Results have particular relevance for how escape responses become anticipatory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feedback stimuli and the extinction of avoidance responding in rats.

Trained 24 female Wistar rats to avoid electric shock in a 2-way shuttlebox with a feedback stimulus contingent upon each avoidance response in order to investigate extinction of the avoidance response. Shock presentations were then discontinued. Results indicate that the temporal relationship of the avoidance response and feedback was disrupted by continuously presenting the feedback stimulus or by random presentations of the stimulus. These procedures prolonged extinction relative to complete withdrawal of the feedback, but enhanced extinction relative to response contingent presentations of the feedback. Parallels between patterns of extinction found with these procedures and those found with appetitive reinforcers are discussed. (French abstract) (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Time course of effects of septal lesions on avoidance, response suppression, and reactivity to shock.

Conducted 4 experiments with a total of 99 male albino Sprague-Dawley rats with septal lesions and 76 sham-operated controls. Ss tested 5 or 10 days, but not 2 days, after septal lesions acquired a 2-way conditioned avoidance response faster than controls. Punishment in a passive-avoidance test was least effective in suppressing milk-licking 2 days after septal lesions, and increased in effectiveness as a function of time after surgery. All experimental Ss were significantly more reactive to footshock than controls in a jump-flinch test. Results support the hypothesis that different aversively-controlled behaviors are mediated by different mechanisms within the septum. (31 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitation and nonfacilitation of active avoidance behavior of rats with septal lesions in the shuttle box and running wheel.

Hypothesized that facilitation of avoidance performance of rats with septal lesions occurs only in tasks that punish responses having the same topography as the avoidance response, such as intertrial responses, or tasks that have aversive consequences for making the avoidance response, such as a brightly illuminated safe compartment. 28 male Sprague-Dawley rats (Exp I) were trained in 2 shuttle box tasks, and 24 (Exp II) were trained in 2 running-wheel avoidance tasks under conditions of punishment or nonpunishment of intertrial responses. Ss with septal lesions performed better than controls in both the shuttle box and the wheel tasks when intertrial responses were punished. When intertrial responding was not punished, experimental and control groups did not differ in avoidance performance. Avoidance performances of punished and unpunished Ss with septal lesions did not differ from each other or from unpunished controls in either wheel or shuttle box tasks. Results are discussed in the context of the species-specific defense reaction (SSDR) avoidance theory of R. C. Bolles (see record 1970-04813-001). It is suggested that septal lesions interfere with the suppression of ineffective SSDRs. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term effects of leucine-enkephalin on active avoidance responding in mice.

Studied the effects of peripherally administered leucine-enkephalin (LE [200 μg/kg]) on the acquisition and retention of active avoidance behavior in 202 male Swiss-Webster mice. Ss received 4 training trials on Day 1, 24 test trials on Day 2, and 10 test trials on Day 5. LE impaired the acquisition of avoidance behavior when administered before testing on Day 2. Impairment of retention was demonstrated on Day 2 and Day 5 when LE was administered immediately after training on Day 1, results indicating the long-term nature of the enkephalin effect. There was no effect of LE when administered just prior to testing on Day 5. The impairing effect was attenuated but not blocked by naloxone (10 mg/kg). Results support the hypothesis that LE impairs both acquisition of learning and memory consolidation. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extinction of avoidance responding in rats: The noise-intensity parameter in noise-facilitation of flooding.

60 female hooded rats were given unsignaled avoidance training in the jump-up apparatus developed by the 1st author (1970) and were given a period of flooding followed by extinction testing. During flooding, 4 groups of 15 Ss each received different intensities of continuous white noise. The noise systematically changed spontaneous behavior during flooding and increased the efficacy of flooding in hastening extinction in a roughly monotonic fashion. The louder the noise during flooding, the greater were these effects. Findings are explained in terms of 3 theoretical frameworks: (1) 2-process fear theory, (2) the notion of adaptation to stress, and (3) a sign-tracking analysis. (French abstract) (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversive schedules with independent probabilities of reinforcement for responding and not responding by rhesus monkeys: III. Recovery of avoidance baseline.

Investigated the effect of prior response history on subsequent avoidance responding. In Exps I and II, using 12 and 10 male rhesus monkeys that had served in previous experiments by the authors (see PA, Vol 53:Issue 6), up to 5 sequences of aversive stimulus presentation schedules provided a range from no responding to complete avoidance response recovery, whether with or without signaled shock. Exp III, with 12 naive rhesus monkeys, demonstrated that the same range of avoidance response recovery could be obtained by the use of only selected schedules rather than a prolonged sequence. These findings provide further support for the power of 2 independent probability variables, governing reinforcement delivery for responding or nonresponding, for generating schedules of reinforcement. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Corticosterone and avoidance in rats with basolateral amygdala lesions.

Produced deficient acquisition of 2-way active and passive avoidance in 15 male Moll-Wistar rats after bilateral electrolytic lesions restricted to the dorsal part of the basolateral nuclei. Other deficits also suggest a general reduction in fear or arousal: less immobility in the open field and during active-avoidance intertrial intervals, and slower escape latencies and less pituitary-adrenal activation during the initial active-avoidance session. Anatomical analysis of the areas producing the greatest deficit suggests that differential involvement of the insula may explain phylogenetic differences between these data from the rat and previous data from the cat, which show only active-avoidance deficiency after basolateral lesions. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The hippocampus and reward: Effects of hippocampal lesions on progressive-ratio responding.

Two experiments investigated the effects of ibotenic-acid lesions of the hippocampus on food-rewarded performance under a progressive-ratio 10 schedule of reinforcement. The results of Experiment 1 indicated that rats with hippocampal lesions showed profound increases in breakpoint and enhancements in the efficiency of responding. In a second experiment the same rats were challenged with prefeeding, increases in the height of the response lever, and the substitution of sucrose-based for grain-based reward pellets. Responding in both groups was similarly reduced by prefeeding and increases in the effortfulness of responding, but lesioned rats were significantly more responsive to the change to sucrose reward. Overall, the results indicated that hippocampal damage increased responding by enhancing the activational or hedonic properties of the delivered food pellets, while not affecting food-motivation or the motor capacity to respond. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in strains of rats during extinction of shuttle box avoidance responding.

In 2 experiments differences between strains of rats in the extinction of shuttle box avoidance responding were examined as a function of the classical conditioned stimulus-unconditioned stimulus (CS-UCS) and instrumental CS termination contingencies. Ss were a total of 68 female albino Fischer, Lewis, and Long-Evans rats. When classical CS-UCS pairings were given on all trials, responding declined somewhat. When this contingency was altered by omitting shock entirely or preventing the pairing of CS and shock, behavior weakened even further. Whereas responding was indistinguishable under both prompt and delayed CS termination during the paired-shock procedure, it was generally higher under prompt CS termination during the no-shock and unpaired-shock procedures. However, the strains differed widely during extinction, with Fischer rats responding more often during the paired and unpaired procedures and Long-Evans rats more often in the no-shock procedure. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)