Persistence of runway performance after septal lesions in rats.

Assigned 32 male Wistar albino rats to groups receiving bilateral septal lesions or control operations. Septal lesions prevented the partial reinforcement extinction effect after 48 acquisition trials. Septal Ss showed increased resistance to extinction following continuous reinforcement but decreased resistance to extinction following partial reinforcement. Analysis of the acquisition data indicated that the lesions retarded the development of approach-avoidance conflicts associated with reward and nonreward. In a 2nd study, 16 septal and 16 control Ss received 96 acquisition trials. Extended training allowed the development of conflict responses under partial reinforcement, and the Ss with lesions were indistinguishable from controls during extinction. Following continuous reinforcement, septal lesions produced slower extinction of response. It is concluded that the lesions interfered with the development of feedback from frustration, approach-avoidance conflicts, and frustration tolerance. (21 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)     

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)     

Differential effects of septal, preoptic, and habenula ablations on thirst-motivated behaviors in rats.

Two experiments used a total of 59 male Sprague-Dawley rats. Bilateral septal lesions dramatically enhanced barpressing rates generated under progressive ratio schedules of reinforcement. This increased barpressing was dependent on deprivation level but independent of the type of deprivation (i.e., food or water). Equivalent effects on barpressing were observed in Ss with bilateral medial forebrain bundle lesions at the level of the lateral preoptic area. Septal lesions, medial forebrain bundle lesions, and habenula lesions did not result in a hyperreactivity to bitter quinine solutions. Hyperreactivity to quinine was observed only in Ss with medial preoptic lesions. This medial preoptic lesion also impaired operant responding for water on a progressive ratio schedule of reinforcement. It is suggested that the medial preoptic lesion produced a deficit in thirst-motivated behavior. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

DRL performance, extinction, and secondary reinforcement: Role of appetitive value of food in mice with septal lesions.

Conducted 5 experiments with a total of 116 B6D2F-sub-1/J mice. Normal Ss and Ss with septal lesions were trained on a DRL 8-sec schedule for food reinforcement varying in incentive value. Dilution of diet increased the number of reinforcements received by Ss with septal lesions. In Exps II and III the effects of septal lesions on resistance to extinction after continuous reinforcement training and the strength of secondary reinforcement were investigated. Changes in reinforcement value modified the septal lesion effects in both cases. All 3 experiments demonstrated the alteration of the septal lesion effect through a change in the appetitive value of the reinforcement. Results suggest that one of the mechanisms by which septal lesions impair DRL performance is an enhancement of reinforcing properties of food. (25 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)     

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)     

Paleostriatal lesions in the pigeon (Columba livia) potentiate classical conditioning: Evidence from fixed-interval responding, free operant go–no-go discrimination, and alternation.

Explored the existence of behavioral deficits in the paleostriatum augmentatum in 4 experiments in which pigeons were given bilateral electrolytic lesions. Exp I, conducted with 16 Ss, investigated the effects of lesions on keypecking for reinforcement on a 1-min FI schedule. The lesions increased total response rates, but response timing was not disrupted in paleostriatal Ss. In Exp II, 17 naive Ss were given VI baseline training and, in contrast to the results of Exp I, paleostriatal lesions did not increase responding. Go–no-go discrimination, which followed baseline training, revealed enhanced positive behavioral contrast in paleostriatal Ss, which was explained in terms of additivity theory. The results of Exps I and II suggest that potentiated classical conditioning occurred in paleostriatal Ss. In Exp III, 16 naive Ss were given spatial alternation training, and performance was temporarily impaired following paleostriatal lesions. The same paleostriatal Ss showed superior differentiation performance in Exp IV with a classical go–no-go alternation procedure (which also suggested potentiated classical conditioning). It is argued that disruption of (irrelevant) response-produced information may account for paleostriatal superiority. (55 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)     

Limbic lesions and the energizing, aversive, and inhibitory effects of non-reward in rats.

Tested 30 male albino Wistar rats with bilateral lesions in the amygdala, septum, hippocampus, stria terminalis, and fornix on a multiple reinforcement schedule in which barpressing in one component was associated with VI reinforcement (S+) and the other with extinction (S–). Responses on a 2nd lever turned off S– for 5-sec periods during the extinction component. All groups, with the exception of Ss with amygdaloid lesions exhibited behavioral contrast. Ss with hippocampal or fornical lesions showed greater resistance to extinction. Response rates on the lever that turned off S– were higher after stria terminalis and septal lesions, whereas lower rates were obtained from Ss with amygdaloid lesions. It is concluded that amygdaloid lesions attenuate the energizing and aversive effects of nonreward, septal and stria terminalis lesions increase the aversive effects, and hippocampal and fornical lesions interfere with the inhibitory effects of nonreward. (French summary) (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preference for mode of obtaining reinforcement in rats with lesions in septal or ventromedial hypothalamic area.

Assigned 54 female Holtzman albino rats to groups receiving sham operations, septal lesions, or ventromedial hypothalamic lesions. In a choice situation where food could be obtained free or by working, lesioned Ss obtained significantly more reinforcement by bar pressing than by not working. This preference for obtaining reinforcement by bar pressing was evident in normal and operated Ss even when different amounts of effort (fixed ratios of l, 3, ll) were required to obtain reinforcement. When adulterated pellets were substituted for regular pellets, operated Ss continued to obtain significantly more reinforcement by bar pressing than normal Ss. Findings indicate the limitation of the explanation that rats with lesions in the ventromedial hypothalamus have reduced appetitive motivation or a general motivational deficit. (21 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesions of the amygdala, but not of the cerebellum or red nucleus, block conditioned fear as measured with the potentiated startle paradigm.

In Exp I, 97 male Sprague-Dawley albino rats were given 10 light–shock pairings on 2 successive days. At 24–48 hrs following training, groups of Ss received bilateral transection of the cerebellar peduncles, bilateral lesions of the red nucleus (which receives most of the cerebellar efferents), or bilateral lesions of the central nucleus of the amygdala. Controls were sham operated. At 3–4 days after surgery, Ss were tested for potentiated startle (PS [increased acoustic startle in the presence of the light previously paired with shock]). PS was blocked by lesions of the central nucleus of the amygdala but not by transection of the cerebellar peduncles or lesions of the red nucleus. Exp II, in which a visual prepulse test was used with 14 Ss, indicated that the blockade of PS observed in Ss with amygdala lesions could not be attributed to optic tract damage. Exp III, with 20 Ss, demonstrated that the absence of potentiation in Ss with amygdala lesions was not simply due to a lowered startle level ceiling, because these Ss could show increased startle with increased stimulus intensity and with administration of intraperitoneal strychnine, (0.75 mg/kg), a drug that increases startle. Results are consistent with the hypothesis that the amygdala is involved in fear conditioning. (64 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of hippocampal lesions and intertrial interval on single-alternation performance in the rat.

Trained 7 unoperated male Long-Evans hooded rats and 14 Ss with bilateral hippocampal or cortical lesions made by aspiration on a go, no-go task in which bar presses were reinforced on alternate trials. Performance was evaluated with both latency ratios (latency to 1st response on go trials/latency to 1st response on no-go trials) and response ratios (total responses on no-go trials/total responses on go trials). Ss were trained to criterion at successively increasing durations of ITI (10, 20, 40, and 80 sec.). While Ss with hippocampal lesions acquired the task more rapidly than controls with the initial 10-sec ITI, they were severely impaired when tested with the longer ITIs. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of simultaneous and successive septal and amygdaloid lesions on social behavior of the rat.

Tested the social cohesiveness in an open field of 96 male hooded Long-Evans rats which had been subjected to either simultaneous or successive septal and amygdaloid lesions. Both the increased cohesiveness of Ss with septal lesions and the decreased cohesiveness of Ss with amygdaloid lesions were attenuated by the addition of the 2nd lesion. Ss with simultaneous lesions did not differ from controls. The 2 structures also were demonstrated to be reciprocally involved in mediating activity levels. (16 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)     

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 septal lesions on inter- and intraspecies aggression in rats.

Conducted 3 experiments with septally lesioned and sham-operated male Sprague-Dawley albino rats (n = 97). Septal lesions affected shock-induced fighting, mouse killing, and fighting in a dominance situation differentially, depending on situational and temporal variables. Immediately following the lesion, preoperatively dominant Ss became submissive in a food competition test, displayed increased fighting in response to electric shock, and killed mice. 15 days after surgery, these effects on fighting behavior were no longer present. If tested for the 1st time 10-15 days after the lesion, septal Ss maintained their dominance in the food competition test, did not show an increase in shock-elicited fighting, and did not turn into "killer" rats. The effects on the muricide response were not reversible once they had been induced. (32 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Proactive behavioral effects of theta-driving septal stimulation on conditioned suppression and punishment in the rat.

In 2 experiments, a treatment phase of septal stimulation preceded the acquisition of free operant leverpressing on a random-interval 64-sec reinforcement schedule. 32 male Sprague-Dawley rats were chronically implanted with a bilateral septal stimulating electrode and a unilateral bipolar hippocampal recording electrode. Ss received (a) low-frequency (7.7 Hz) stimulation, which drove the hippocampal theta rhythm; (b) random-pulse stimulation (average frequency 7.7 Hz), which produced only nonregular waveforms in the hippocampus; or (c) no stimulation. After 12 days of leverpress acquisition, Ss were presented while leverpressing with an auditory signal associated with a particular schedule of shock delivery: In Exp I, shocks occurred despite the S's response strategy; in Exp II, shocks were delivered only if the S pressed the lever. In both experiments, leverpressing was suppressed by the auditory stimulus. Theta-driving but not random-pulse septal stimulation proactively increased behavioral tolerance to the effects of electric shock. Results support the idea that proactive behavioral effects of septal stimulation are a consequence of the production of the hippocampal theta rhythm. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of the frustration effect and the partial reinforcement extinction effect after limbic lesions in rats.

20 male albino Wistar rats with control operations, 20 with lesions in the amygdala, and 20 with lesions in the septal area were tested in a double runway. Results show that after omission of reward in the 1st goal box on 50% of the trials, control and septal Ss showed a frustration effect. Lesions in the amygdala eliminated this effect. Subsequent tests of extinction behavior indicated that Ss with control operations and Ss with damage in the amygdala showed a partial reinforcement extinction effect whereas Ss with septal lesions did not. It is concluded that frustration effects and extinction effects have independent neural substrates. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental aspects of recovery of function following septal lesions in the infant rat.

In an experiment with 4 litters of Long-Evans hooded rats (14 pups/litter), 1/2 of each litter received septal lesions at the age of 7 days, and the remaining 1/2 received control operations (incision). Septal lesions in infant Ss resulted in hyperemotionality and altered open-field behaviors at the ages of 21, 42, 63, and 90 days. When Ss reached 90 days of age, their behavior was compared with that of normal adult rats and rats that had received septal lesions in adulthood. Measures of active avoidance, fixed-ratio responding, and social facilitation were collected for all groups. Results show that septal lesions in infancy or adulthood enhanced avoidance responding, fixed-ratio responding, and social behavior when compared with infant or adult controls. Failure to observe recovery of function was interpreted in terms of phylogeny and hierarchical cerebral organization. (26 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)