Effects of septal lesions on factors of mouse emotionality.

60 mice from 2 emotionally divergent inbred strains, BALB/Alb and C57BL/10Alb, were assigned to 1 of 3 experimental groups: septal surgery, control surgery, and intact. All Ss were then administered a battery of 5 tasks that yielded 19 measures of emotionality. Factor scores wre computed on 6 invariant factors obtained previously from these measures. Each factor was assessed by an ANOVA design with main effects for Strain, Sex, Lesion, and Days of Testing. Strain and Lesion main effects were found on the Motor Discharge and Autonomic Balance factors, Strain by Lesion interaction effects on Motor Discharge and Tunneling 1, and a Lesion by Sex interaction effect on Territorial Marking. Results suggest that the septum affects distinct processes modulating Autonomic Balance and Motor Discharge factors. (49 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of different types of organizers on students' learning from text.

Prior to reading a text about computer crime and prevention, eighth graders read one of four types of operationally defined organizers: concept, analogy, outline, or dummy. While reading the text, students matched paragraphs of the text to numbered sections in the organizer, leaving a trace that was scored to reflect their actual use of the organizer while reading the text. Multiple regression analyses of multiple-choice and short answer achievement measures showed no main effects of type of organizer. However, students in true advance organizer groups (concept and analogy) who were able to use the organizers effectively, as indicated by higher trace scores, outperformed students in the outline and dummy groups. Analysis of trace scores revealed that students had difficulty connecting information in the concept and analogy organizers to the text. These findings indicate that simply presenting a genuine advance organizer does not guarantee that students will use it effectively. However, when students did use an advance organizer effectively, achievement increased slightly. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Opposite effects of lateral septal LTP and lateral septal lesions on contextual fear conditioning in mice.

The effect of fimbrial high-frequency stimulation (HFS)-induced long-term potentiation (LTP) in the lateral septum (LS) on contextual fear conditioning was studied in mice. Mice were conditioned for fear toward a novel context through the use of footshocks. The 1st experiment showed that pretraining HFS reduced significantly conditional freezing to contextual stimuli. The 2nd experiment was designed to determine whether the reduction of freezing produced by fimbrial HFS resulted from LTP in the LS rather than from LTP in other brain structures. Accordingly, mice with lesions of the LS were used and submitted to the same protocol as in the 1st experiment. Results showed that LS lesions completely abolished the impairing effect of fimbrial HFS and, as a whole, potentiated the freezing response. These data suggest that contextual fear conditioning is strongly modulated by the level of hippocampal–LS synaptic neurotransmission. (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)     

Differential effects of posterior septal lesions on dispositional and representational memory.

[Correction Notice: An erratum for this article was reported in Vol 101(1) of Behavioral Neuroscience (see record 2008-10683-001). A phrase was erroneously deleted from the text. In the seventh paragraph on p. 713, the second sentence should read as follows: Early in training individual differences were great, but by the end of adaptation training, individual differences were quite small and all rats responded at close to asymptotic speeds.] A distinction between 2 classes of memory has been made in terms of the sensory availability of cues at the time of making discriminations that are influenced by past experience. Three tasks objectively defining this distinction were learned in a T-maze by 36 male Long-Evans rats in 3 groups: (a) a delayed non-matching-to-sample (DNMTS) that depended on representational memory; (b) a simple sensory discrimination (SD) that depended on dispositional memory; and (c) a more difficult discrimination that also depended on dispositional memory, called the simultaneous conditional discrimination (SCD). The DNMTS and SD tasks were acquired quickly; the SCD task took many more trials. Posterior septal lesions impaired DNMTS performance but had no effect on retention of tasks that depended on dispositional memory. Results indicate that dispositional and representational memory systems have at least partially distinct anatomical substrates in the brain and that it is the representational and not the conditional aspects of the DNMTS task that are impaired by the septal lesions. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decisional analysis of the effects of limbic lesions on learning in monkeys.

Examined the hypothesis that behavior during discrimination learning and reversal is under control of 2 competing variables: the patterned cues to be discriminated and the noncontingent schedule of reinforcement. An experiment was conducted with 8 adolescent rhesus monkeys using a modified decision theoretic procedure. Results show that the 2 variables were operative and that noncontingent reinforcement produced a strong position bias against discriminating. This bias was quantitatively more easily overcome by normal Ss than by Ss with hippocampal-amygdala lesions though the strategy and tactics used were the same for both groups. It is concluded that the hippocampus and amygdala influence attention through mechanisms that regulate motivational bias. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparison between the effects of medial septal lesions and entorhinal cortex lesions on performance of nonspatial working memory tasks and reversal learning

Two studies explored the relationship between cognitions and long-term symptoms in adult child sexual abuse (CSA) survivors. In Study 1, an American sample of 43 survivors completed questionnaires assessing attributional style and dysfunctional beliefs in cognitive themes affected by victimization, as well as measures of posttraumatic symptoms. Survivors' attributions of negative events were more internal, stable, and global than those of 29 comparison subjects without a history of CSA. However, only the globality scale was significantly related with severity of long-term symptoms. High correlations between dysfunctional beliefs concerning safety, trust, esteem, or intimacy, and posttrauma symptoms were found. The latter finding was replicated in Study 2 with a German sample of 35 CSA survivors, even when controlling for frequency of abuse.     

Mathematical competencies in children with different types of learning difficulties.

The mathematical performance of 182 third and fourth graders in 8 different areas of mathematics was examined. The children belonged to 4 achievement groups: children with mathematic difficulties (MD only), children with both mathematic and reading difficulties (MD-RD), children with reading difficulties (RD only), and normally achieving children (control group). Both MD groups performed worse than the normally achieving children in all but 1 area, place value knowledge. The MD-only and the MD-RD children performed equally in all areas of mathematics. The RD-only group performed at the same level as the control group on all areas of mathematics. The study provides further evidence that fact retrieval deficits are a cardinal characteristic of children with MD. The MD children's substantial difficulties with mathematic word problem solving can be attributed to several processes involved in problem solving. Besides poor skills in multidigit calculation, arithmetic fact retrieval, and poor understanding of calculation principles, children with MD might have deficits related to specific problem-solving processes such as establishing a problem representation and developing a solution plan. (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)     

Impact of different types of cooperative learning on cross-ethnic and cross-sex relationships.

Hypothesized that the effects of cooperative experiences on cross-ethnic and cross-sex relationships would be strongest for structured class activities, next strongest for unstructured class activities in the broader school environment, and least strong for activities in students' homes. In Study 1, 74 6th graders were randomly assigned to 3 conditions (cooperative controversy, cooperative debate, and individualistic) stratifying for sex, ability level, and ethnic membership. Ss participated in the study for 55 min/day for 11 instructional days. In Study 2, 51 4th graders were randomly assigned to 2 conditions (intergroup cooperation and intergroup competition) stratifying for sex, ability, and ethnic membership. Ss participated in the study for 55 min/day for 10 instructional days. An activity report scale was administered to Ss to determine with whom they interacted in structured class activities, unstructured class activities, school activities outside of class, and activities in the home. Results show that in Study 1, both the cooperative controversy and cooperative debate conditions promoted more positive cross-sex and cross-ethnic relationships than did individualistic learning. In Study 2, intergroup cooperation promoted more positive cross-sex and cross-ethnic relationships than intergroup competition. Relationships formed within cooperative learning situations did not generalize into unstructured class, school, and home activities. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of prefrontal lesions and combined prefrontal and limbic lesions on subsequent learning performance in the cat.

15 cats were given lesions in either the prefrontal cortex alone (n?=?7) or in the prefrontal cortex, anterior thalamus, mamillary bodies, and subiculum (n?=?8) before being tested in the acquisition of visual-reversal, delayed-alternation, and 2-way active-avoidance tasks. Lesioned Ss were compared to 6 unoperated and 4 sham-operated controls. As an extension of E. Irle and H. J. Markowitsch's (see record 1984-19842-001) study, in which triple limbic lesions failed to impair learning behavior of cats, the present study examined the effects of a lesion in the 4th brain structure (in addition to the original triple lesions). Results indicate that, compared with controls, Ss with prefrontal lesions were impaired in the acquisition of the avoidance task. In contrast, Ss with combined lesions were unimpaired in the acquisition of the visual-reversal task, facilitated in the acquisition of the avoidance task, but impaired in the acquisition of the delayed-alternation task. The superior performance Ss with combined lesions is interpreted as due to a lesion-induced functional shift acting on intact brain structures which, prior to massive limbic lesions, remained inhibited. (56 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociations among the anxiolytic effects of septal, hippocampal, and amygdaloid lesions.

Fear reactions of rats given bilateral lesions to the septum, hippocampus, or amygdala were compared with those of rats given sham lesions, in 2 animal models of anxiety: the shock-probe burying test and the elevated plus-maze test. Septal lesions produced anxiolytic effects in both tests (i.e., an increase in open-arm activity and a decrease in burying), whereas hippocampal and amygdaloid lesions produced neither of these effects. On the other hand, hippocampal and amygdaloid lesions impaired rats' passive avoidance of the electrified shock-probe, whereas septal lesions did not. These dissociations suggest that limbic structures such as the septum, amygdala, and hippocampus exert parallel but distinct control over different fear reactions. (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)     

The effects of septal, thalamic, and tegmental lesions on general activity in the hooded rat.

Compared 19 male hooded rats with either septal, medial thalamic, or tegmental reticular formation lesions on 3 measures of spontaneous activity (a brief test in a novel maze and 7-day tests in running wheels or photocell cages). Wheel running was depressed by all the lesions (especially septal and tegmental), whereas cage activity and locomotion in the maze were unaffected. Septal-damaged Ss groomed more than all other groups and reared less than 7 controls in the maze. Rearing in the maze and running in the wheels were positively correlated and both were negatively correlated with grooming in the maze. Results are discussed in terms of competing-response classes and 1-factor hypothesis of the neural control of spontaneous behavior. (French summary) (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Influence of neonatal septal lesions on DRL performance in adulthood.

Reports 2 experiments on the influence of neonatal septal lesions on responding of 75 Long-Evans hooded rats trained on a DRL schedule in adulthood. Rats given septal lesions at 1 or 7 days after birth emitted a significantly higher number of responses and earned fewer reinforcements than did those given control electrode insertions. Thus, the inefficient performance on the DRL schedule, often observed after septal lesions in adulthood, does not depend upon the age of the S at the time of the lesion. Furthermore, operant training given at an early age (25-45 days) to Ss with neonatal septal damage did not facilitate performance when they were retrained in adulthood. In short, septal lesions at any age lead to permanent impairments of performance on a DRL 20-sec schedule. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Double dissociation of effects on learning of medial versus lateral hyperstriatal lesions in pigeons.

Three experiments examined the effects of medial and lateral hyperstriatal lesions in two groups of pigeons. In Experiment 1, both hyperstriatal groups were impaired, relative to unoperated and operated control groups, in postoperative performance of preoperatively acquired serial reversal of both spatial and visual discriminations. The deficits of the two hyperstriatal groups appeared both quantitatively and qualitatively similar. Experiment 2 found that performance of spatial reversals was disrupted in the medial, but not in the lateral, hyperstriatal group by a long intertrial interval. Experiment 3 found that acquisition of simultaneous matching-to-sample was disrupted by lateral, but not by medial, hyperstriatal lesions; the lateral group also showed a lower rate of response to the sample stimulus than any of the other groups. Implications of these findings for current theories of hyperstriatal function are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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)     

Lateral septal lesions enhance conditioned bradycardia in the rabbit.

52 New Zealand albino rabbits received sham lesions or complete, medial, lateral, or posterior septal lesions and were subjected to differential conditioning in which tones of different frequencies served as CSs, and paraorbital electric shock was the UCS. EMG, heart rate (HR), blood pressure (BP) CRs, and hippocampal rhythmic slow wave activity (RSA) were recorded. Lateral or complete septal lesions enhanced the bradycardiac HR CR but had no effect on the BP depressor response. Both unconditioned and conditioned EMG responses occurred infrequently and were unaffected by any lesion. Unconditioned HR responses and somatomotor threshold determinations to unsignaled electric shock were also unaffected by the lesions. Complete septal lesions increased locomotor activity relative to sham or other septal lesions. Little hippocampal RSA was detected in Ss with medial lesions, but the HR CR was unimpaired in these Ss. Data implicate the septo-hippocampal circuit in classical conditioning of cardiovascular changes and further suggest that diencephalic forebrain structures may modulate forebrain processing of sensory stimulation, perhaps in terms of assessing its biological significance. (41 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Long-term effects of selective neonatal temporal lobe lesions on learning and memory in monkeys.

Rhesus monkeys with neonatal damage to either the medial temporal lobe or the inferior temporal cortical area TE, and their normal controls, were reassessed in visual habit formation (24-hour intertrial interval task) and visual recognition (delayed nonmatching to sample [DNMS]) at 4–5 years of age and then tested on tactile and spatial DNMS. Results on the two visual tasks were the same as those obtained when the monkeys were under 1 year of age. Specifically, early medial temporal lesions, like late lesions, left habit formation intact but severely impaired recognition memory. Furthermore, the memory deficit extended to the tactile and spatial modalities. By contrast, early damage to TE, unlike late damage to it, yielded only mild deficits on both visual tasks and had no effect on tactile or spatial DNMS. Compensatory mechanisms that promote substantial and permanent recovery thus appear to be available after neonatal TE lesions but not after neonatal medial temporal lesions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)