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)     

Immediate effect of septal area damage on DRL performance in the rat.

Investigated the immediate and long-term effects of septal area lesions on performance on a differential reinforcement of low rates (DRL) 10-sec schedule. Ss were 43 male albino rats. Septal area lesions produced immediate disruption of DRL responding in unanesthetized Ss, but cingulate area lesions or sham treatments did not. The induction of septal seizures without lesions produced only minimal disruption. For the first few testing sessions, Ss tested 7 days after receiving septal area lesions were indistinguishable in DRL performance from those tested immediately; the former, however, showed poorer recovery. It is concluded that neural or other changes requiring time to develop postoperatively are not essential to the disruption of DRL performance, but they may impede behavioral recovery. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Collateral behaviors and the DRL deficit of rats with septal lesions.

Trained a total of 31 male Long-Evans hooded normal and septally-lesioned rats to lever press for food on a DRL 20-sec schedule in either a conventional operant chamber or 1 containing wood blocks and cardboard strips. The DRL behavior of normals trained in modified chambers was most efficient, and that of Ss with septal lesions trained in conventional chambers was least efficient. After 35 hr. of training, normals tested in conventional chambers and Ss with septal lesions tested in modified chambers did not differ significantly. Ss chewed the blocks and cardboard, and prevention of these collateral behaviors reduced DRL efficiency. Results show that colalteral behaviors facilitate the development of efficient DRL behavior and indicate that the DRL deficit of rats with septal lesions can be modified. (17 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)     

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)     

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)     

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)     

Cued DRL training: Effects on the permanence of lesion-induced overresponding.

Attempted to determine the degree to which lesions in the septum and anatomically related structures result in the presence and/or permanence of overresponding on a DRL 20-sec schedule. Male Long-Evans hooded rats were given 15 days of training to determine the presence or absence of overresponding. Ss that overresponded were divided into 2 groups, with one receiving 15 days of cued DRL training and the other receiving 15 days of regular DRL training. Overresponding occurred in 60 Ss following lesions in septum, hippocampus, medialis dorsalis, and ventral thalamus pars dorsalis. While in effect, cued DRL facilitated performance in 8 controls and in operated Ss but did not facilitate performance when removed in septals. Exposure to the cued DRL allowed hippocampals to reduce responding and increase the frequency of obtained reinforcements. Lesions in medialis dorsalis and ventral thalamus led to an overresponding that disappeared with prolonged regular DRL training. Cued DRL training actually functioned as a time-out from DRL training. Variations in the permanence of the overresponding symptom according to lesion locus preclude identification of the lesion-induced dysfunction based solely on the presence or absence of overresponding. (18 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)     

Classical differential and operant conditioning in rabbits (Oryctolagus cuniculus) with septal lesions.

12 normal New Zealand white rabbits and 12 with septal lesions received classical differential conditioning of the nictitating membrane response (NMR), followed by auditory generalization tests run in extinction. Although rate of acquisition and asymptotic responding to positive conditioned stimuli did not differ, septals responded more than normals to nonreinforced stimuli. Resultant decrements in differential conditioning could not be attributed to changes in auditory or shock thresholds or to increased spontaneous NMRs. Septals also responded at higher rates in both operant conditioning (barpresses reinforced with food pellets on a variable interval schedule) and extinction sessions. No difference in suppression in a passive avoidance task was found. Results are discussed in relation to R. A. McCleary's (1966) response disinhibition analysis of septal function, and an habituation hypothesis is considered. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Septal lesions and incentive expectancies in rats.

Tested male albino Wistar rats with bilateral septal lesions on a multiple DRL schedule with large and small rewards. The lesion produced less efficient DRL performance under both conditions. Small rewards produced more efficient DRL responding in controls and brain-damaged Ss. A 2nd study investigated runway conditioning under immediate, delayed, and no reward. Septal lesions increased running speeds with immediate reward, maintained faster speeds during the early delayed-reward trials, but produced no differences during extinction. A 3rd experiment investigated the effects of immediate and delayed rewards on auditory discrimination learning in septal and control Ss. Brain-damaged Ss showed inferior discrimination performance with delayed rewards but not with immediate rewards. Data suggest that septal lesions alter cognitive strategies (i.e., expectancies) based on incentive characteristics. (French abstract) (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of adrenocorticotropic hormone on conditioned avoidance in rats interpreted as state-dependent learning.

140 male Charles River CD rats were given 1 training trial that was followed 2 days later by 1 test trial in a "step-out" passive avoidance task. Each S was injected with either ACTH or placebo before training and before testing. 4 groups of Ss were used, representing the 4 possible training-testing injection combinations: placebo-placebo, placebo-ACTH, ACTH-placebo, and ACTH-ACTH. ACTH given in testing increased avoidance for subjects that had received ACTH in training and decreased avoidance for those that had received placebo in training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attenuation of reversal deficits of mice with septal lesions by shifts in the motivational context.

Response perseveration following septal lesions (SLs), demonstrated on tasks that require change of a learned pattern of responding, depends in part on a relatively constant motivational context. The present experiment examined the effects of concurrent changes in the temperature of the water in a water-escape maze and the reversal of a spatial discrimination in 83 male Binghamton heterogeneous mice that had received either SLs or control surgery. Control and experimental Ss were trained on a spatial discrimination in either 17 or 34°C water. Following acquisition, reversal training was conducted in the maze filled with the same temperature water used during acquisition, or both water temperature and spatial reinforcement contingencies were reversed. When the water temperature remained constant across acquisition and reversal, Ss with SLs showed persistence during reversal training. Changing the water temperature concurrently with the institution of reversal training attenuated the perseverative deficits of Ss with SLs, in contrast to the relative lack of effect in controls. The role of the septal region in attention is discussed. (28 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)     

Performance of rats on the Maier Three-Table Task following septal lesions occurring 24 hours after birth.

Two experiments with 85 Long-Evans hooded rats studied whether behavioral sparing would be demonstrated when septal lesions occurred prior to the age at which the tested behavior first appears in normal rats. Ss given septal lesions at 1 or 7 days after birth performed at approximately chance on the Maier 3-table task when tested at 90 days of age. Ss that had control electrode insertions at the same ages performed at a level similar to normal Ss. Ss given septal lesions at either age explored significantly more than did control Ss. Results are discussed in terms of the constancy over time of the septal contribution to performance on the 3-table task and the involvement of the septum and hippocampus in the processing of spatial information. (50 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pretraining effects on performance of rats with hippocampal lesions.

Investigated the role of pretraining factors in the overresponding observed on differential-reinforcement-of-low-rate (DRL) schedules following hippocampal lesions. 24 Long-Evans hooded rats divided into unoperated Ss and Ss with large or small hippocampal lesions were given 10 or 20 days of continuous reinforcement (CRF) pretraining before exposure to a DRL 20-sec schedule. Either large lesions or extended CRF pretraining resulted in only a transient elevation in response rates, while the unique combination of a large lesion and extended pretraining was required for persistent overresponding on DRL. It is concluded that the overresponding produced by hippocampal damage is not solely a function of loss of hippocampal tissue but depends upon unique training conditions for its appearance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of problem-solving abilities in the neonatal Peking duck.

294 Peking ducklings, aged 1–24 days posthatch, were tested in 3 experiments involving 3 different problem-solving situations: a delayed response task, spatial habit reversal learning, and a detour problem. In the delayed response task, the length of the delay did not improve significantly with increasing age, averaging 1.6 sec on Day 1 and 2.8 sec on Day 14. In the habit reversal learning, Ss were tested longitudinally beginning on Days 1, 2, 3, and 4. In each group, errors decreased rapidly and progressively with successive reversals, with this steady improvement resembling that found in adult birds and mammals. In the detour problem, groups of Ss were tested longitudinally, beginning on Days 1–6. In groups started at each age, learning was rapid, with criterion usually met within the 1st 1 or 2 days of testing. Even when testing began on Day 1, the Ss typically solved the problem on the 1st or 2nd day of testing, requiring a mean of 10.78 trials to criterion. Results suggest that the neonatal Peking duckling is well equipped to deal with its environment and is capable of a high level of adaptive modification in response to externally imposed stimulus contingencies. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of experience in acquisition and loss of tolerance to the effect of delta-9-THC on spaced responding

Albino rats were given extensive training in spaced responding, using a DRL 30 sec schedule of food reinforcement (only lever presses more than 30 sec apart were reinforced). All rats then went 12 days without behavioral testing. During this period half the rats received daily intragastric doses of delta-9-tetrahydrocannabinol (THC) and the rest equal volumes of the THC vehicle. On day 13, some rats received THC 3 hr before behavioral testing while others received only vehicle. The former showed a sharp increase in lever press rate over baseline levels, but the vehicle control rats were unaffected. The rats with 12 prior THC doses were no less affected than those with no previous drug history. Continued testing resulted in recovery of baseline performance within 5 sessions, again with no effect of previous drug history. Similar results were obtained with doses of 4 mg/kg and 16 mg/kg, though the drug's effects were more pronounced at the higher dose. These results demonstrate that performance in the drug state can be a far more important determinant of tolerance than mere exposure to THC. Drug administration was then suspended for 1 week. Rats that had become tolerant to 4 mg/kg THC were then redivided into 3 new groups. One group received daily doses of vehicle and DRL sessions, a second received DRL sessions without vehicle, and 1 group received neither vehicle nor DRL sessions for this week. Subsequent DRL testing after THC administration showed that only the groups receiving DRL sessions in the intervening week lost their previously acquired tolerance. Experience thus appears to play an important role in loss of tolerance to THC as well as in acquisition of tolerance.     

Enhancement of conjunctive concept attainment in older adults.

Studied 30 community-dwelling females (mean age, 71.4 yrs) to determine whether older adults' performance on a complex concept identification task could be enhanced through training designed to promote the use of a specific problem-solving strategy. Ss were assigned to 1 of 3 groups (training, practice, or control) and were tested individually on the pretest problem followed by the posttest problem 4 days later, with the relevant dimensions used in these problems counterbalanced. Ss were given detailed instructions on all facets of the task. Stimulus cards were presented one at a time, with as much time as needed for response. Ss in the control condition were given only the pre- and posttest problems. The training and practice groups all received 3 additional sessions. Statistical analysis on transformed trials to criterion showed significant main effects due to treatment. The substantially enhanced performance of the trained Ss indicates that a training procedure combining operant and cumulative learning hierarchy principles effectively promoted elderly Ss' use of an appropriate bidimensional conjunctive concept identification strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Deficient passive and one-way active avoidance acquisition following medial forebrain bundle lesions in rats.

In 3 experiments with 93 Long-Evans male hooded rats, cathodal electrolytic lesions of the medial forebrain bundle (MFB) at posterior hypothalamic levels produced a mild, transient hypodipsia and lowered jump thresholds to footshock. Lesions produced marked deficits in passive avoidance performance in a paradigm that paired discrete, linearly incrementing footshock intensities with contact of a water spout following 48 hrs of water deprivation. Injections of levo-dextro-5-hydroxytryptophan (75 mg g, ip), the immediate metabolic precursor of serotonin, had no effect on the passive avoidance performance of either experimental or operated control Ss. Lesions of the MFB also resulted in deficient acquisition in a 1-trial step-through passive avoidance paradigm not using motivation to drink and caused a severe acquisition deficit in a 1-way active avoidance task. Lesions of the septal nuclei produced lowered jump thresholds but did not affect acquisition in the 1st passive avoidance task. Results are interpreted as indicating a lesion-induced deficiency in fear learning, independent of the serotonergic functions of the MFB. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)