Androgens and the organization of sex differences in active avoidance behavior in the rat.

Performed 3 experiments to clarify the role of androgens in the development of sex differences in the acquisition of active avoidance behavior in a total of 248 male and 231 female Holtzman albino rats. Gonadectomy in adulthood did not affect the performance of either sex regardless of the length of the postoperative recovery interval. Neonatal castration also failed to improve the avoidance performance of males, but prenatal exposure to the antiandrogen cyproterone acetate combined with neonatal gonadectomy produced males whose avoidance acquisition and open field activity scores were indistinguishable from those of control females. Prenatal exposure to endogenous androgens was sufficient to organize the avoidance behavior characteristic of normal males, but there is no compelling evidence that exposure to androgens during the prenatal period was critical to this effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemical sympathectomy and avoidance learning in the rat.

Reports results of 5 experiments with male Wistar rats (N = 108). Depletion of peripheral sympathetic noradrenaline induced by administration of 6-hydroxydopamine, ip, led to significant decrements in escape and avoidance responding when the required response was difficult, but not when it was relatively easy to acquire. Results are similar to previous findings obtained with adrenal-demedullated Ss. Findings clarify the role of the sympathetic nervous system in the motivation of behavior elicited by aversive stimulation. Implications for 2-process theory and the "Kamin effect," or "learned helplessness," are discussed. (40 ref.) (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)     

Effects of punishing active avoidance in young and adult rats.

Examined whether age-related differences in suppression occur when a learned response is punished. 8 groups of weanling and adult male Holtzman rats (N = 96) received active-avoidance training and subsequent punishment for that response. Following active avoidance, Ss were assigned to a regular extinction group or to 1 of 3 punishment-delay (0-, 2-, or 10-sec.) groups, which received shock in the goal box. Although weanlings and adults were equivalent in active-avoidance acquisition, under the immediate punishment condition immature Ss required significantly more trials to learn passive avoidance. A delay-of-punishment gradient was obtained in adults but not in weanlings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved avoidance performance following exploratory movement.

Acquisition of 1-way active avoidance is improved by about 40% by (a) exploration in the avoidance apparatus immediately before training; (b) exploration in an irrelevant, empty box immediately before training; (c) a single ECS 24 hr. before training; and (d) a combination of a and c. Exploration in the avoidance apparatus 24 hr. before training did not improve avoidance acquisition. Ss were 69 naive male hooded rats. It is suggested that the effect of exploration on active avoidance performance is due to a "warm-up" of diencephalic-limbic mechanisms concerned with the control of motor activity. (French summary) (17 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interhemispheric transfer of extinction of the active avoidance reaction in rats.

Employed cortical spreading depression (CSD) in 38 hooded Druckrey rats to study the lateralization of extinction of a jumping avoidance reaction. Under unilateral CSD, 181 nonreinforced trials were needed to extinguish the avoidance reaction acquired in 3 100-trial sessions of intact-brain training. During a 2nd extinction session, either with the same or with the contralateral hemisphere depressed, the mean number of trials to the extinction criterion (9 avoidance reactions in 10 consecutive trials) was 39 or 186, respectively. 5 extinction trials performed with the brain intact 1 hr before extinction with contralateral CSD decreased the number of trials to extinction to 98. Thus, extinction of active avoidance can be lateralized and interhemispherically transferred in the same way as acquisition of this habit. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chemical sympathectomy and two-way escape and avoidance learning in the rat.

Reports 6 studies with male hooded Wistar rats on the effects of 2,4,5-trihydroxyphenylethylamine (6-hydroxydopamine) on 2-way escape and avoidance learning. Ss were tested on either escape or avoidance learning at 80 days of age after chemical sympathectomy at birth or 40 or 80 days of age. Neonatal and chronic sympathectomy (at 40 days), but not acute sympathectomy (at 80 days), resulted in depressed escape learning. Avoidance learning was affected by neonatal sympathectomy and partially by acute sympathectomy. Results have implications for the role of the autonomic nervous system in escape-avoidance learning. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Methylphenidate: diurnal effects on locomotor and stereotypic behavior in the rat

The Usher syndromes (US) are a group of inherited disorders that feature autosomal recessive neurosensory hearing loss or deafness with retinitis pigmentosa (RP). Moderate to severe non-progressive high frequency hearing loss with RP and normal vestibular function describes Usher syndrome type IIa, which has been localized to 1q41. Severe retinal degeneration in the inbred mouse strain RBF/DnJ is caused by rd3, a recessive gene located on mouse chromosome 1 distal to akp1 in a region which is orthologous to human 1q32-q42. We evaluated rd3 as a candidate for orthology with USH2A by first reducing and refining the relatively broad region in which rd3 is thought to reside. DNA of offspring from an RBF/DnJ x MOLF/Ei backcross was genotyped with PCR markers closely flanking the predicted location of rd3. Our haplotype analysis re-positioned rd3 to a 3.6 cM region between markers D1Mit273 (cen) and D1Mit209 (tel), consistent with the expected position of an USH2A murine orthologue. Consequently, rd3 is a positional candidate for Usher type IIa. Next we assessed the rd3/rd3 audiological phenotype to see how closely it paralleled that of Usher IIa. Audiological evaluation of mice at various ages revealed evidence of high frequency progressive hearing loss, previously unreported in the RBF/DnJ strain. However, this newly discovered hearing deficit was observed to be inherited independently of rd3, establishing that a completely different gene is responsible.     

Effects of daily administration of methamphetamine on multiple active/passive avoidance performance in rats

The effects of daily methamphetamine (M-Amp) treatment with (2 mg/kg/day, i.p.) were examined on multiple active/passive avoidance performance (MAP) in rats. After avoidance training, the animals were given M-Amp every day; on the days of learning sessions, which were on alternate days, the drug was administered at 15 min before the session. Daily administration of M-Amp produced enhancement of the number of respondings (running) as an excitatory dimension of behavior, disruption of immobilities as an inhibitory dimension, and impairment of successes as a discriminatory dimension, when compared with saline-treated rats. Following M-Amp withdrawal, recovery from these damages of learned behavior was observed, except the deterioration in the discriminative dimension. In conclusion, the MAP paradigm is good for assessing the behavioral effects of M-Amp treatment, making it easy to distinct the behavioral effects of M-Amp into excitatory-inhibitory and discriminative dimensions. It is important to distinguish the behavioral components induced by M-Amp, since the damage of learned avoidance performance consists of different dimensions in the M-Amp-treated rats. Impairment of discriminative behavior appears to demonstrate an attentional deficit, which may explain the behavioral disorderliness in M-Amp abusers who display no disturbance of apparent consciousness. These results are discussed with association of brain monoamine alterations.     

Cholinergic blockade, septal lesions, and DRL performance in the rat.

Reports 4 experiments with a total of 20 male Long-Evans hooded rats describing the effects of cholinergic blockade produced by systemic injection of either atropine sulfate or atropine methyl nitrate on Ss' differential reinforcement of low rate (DRL) responding. It was shown that atropine sulfate injected either chronically or at high dosages suppressed DRL responding. Injected acutely, atropine sulfate produced disinhibitory effects. When atropine was injected either chronically or acutely into Ss with septal lesions, there was suppression of responding. It is suggested that the specific behavioral outcome resulting from cholinergic blockade depends on the balance resulting from the competing peripheral and central effects of such blockade. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Enhanced discriminated bar-press avoidance in the rat through appetitive preconditioning.

In 2 experiments with 57 male albino rats, an appetitive preconditioning procedure produced superior performance on a discriminated bar-press avoidance task. The technique was designed to minimize the number of shocks received early in training and consisted primarily of rewarding Ss with food pellets for an avoidance response in addition to terminating the warning stimulus. Ss so preconditioned were found to achieve sustained, high levels of avoidance. (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)     

Instrumental avoidance conditioning in the spinal rat

Spinal rats exposed to an instrumental avoidance routine in a counterbalanced Horridge paradigm were able to achieve successively higher criteria. Both experimental and yoked control animals were capable of instrumental avoidance conditioning to incremental criteria; experimental animals exhibited retention of the task when tested. During acquisition, naive experimental animals were superior in performance to previous control animals. Due to the use of a counterbalanced Horridge paradigm, the effectsof sensitization and response variability are probably not sufficient to explain all of the results of this experiment. The data suggest that both graded acquisition and retention occur at the spinal level.     

Response initiation and directionality as factors influencing avoidance performance.

Conducted 3 experiments with a total of 234 male Holtzman rats. Results indicate that permitting Ss to run in either of 2 directions to avoid shock (any-way training) resulted in performance superior to that of 1-way or 2-way avoidance. In the any-way condition, Ss often selected a bidirectional mode of responding. Exposure to signaled inescapable shock enhanced avoidance in all avoidance modes. Any-way training enhanced subsequent 2-way avoidance to a greater extent than did 1-way training. Results are interpreted in terms of the need to learn directional responses in avoidance training, role of response initiation in modifying avoidance behavior, and the effectiveness of running responses in determining avoidance performance. (18 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)     

Septal lesions and reasoning performance in the rat.

Conducted 3 experiments in which septal lesions in 14 male Long-Evans hooded rats produced a performance deficit on a task involving the integration of isolated sensory experiences. Neither cingulate nor midline thalamic lesions (N = 7 Ss) had a comparable effect. The deficit in performance by Ss with septal lesions could not be accounted for in terms of an increase in perseverative tendencies. Preoperative experience, although not facilitating reasoning performance in septal Ss, did affect the kinds of errors on the task. 2 possible bases for the observed reasoning deficit are suggested: a failure to attend to relevant stimulus aspects resulting from heightened exploratory tendencies or a loss of recent memory. (30 ref.) (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)     

Domestication, sophistication, and avoidance in Norway rats.

Administered successive 1-way and 2-way avoidance tasks which included treatments of postweaning handling to docility, prior learning sophistication, and differential shock intensity. In this 2-stage paradigm, with 32 wild and 32 hooded Long-Evans rats, escape and avoidance behaviors of wild and laboratory Ss were indistinguishable. Sophistication in laboratory-learning experience and high shock contributed significantly to the performance of both wild and domestic Ss in 1-way, but not 2-way, avoidance. In contrast, effects of handling were apparently negligible. Findings do not support the notion of degeneracy of learning ability in the domesticated rat. (23 ref) (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)     

Transdermal Methylphenidate, Behavioral, and Combined Treatment for Children With ADHD.

Stimulant medication and behavioral treatments are evidence-based for children with attention-deficit/hyperactivity disorder, but the combination of the 2 treatments has been understudied. In this investigation, methylphenidate (MPH) was crossed with 2 levels of behavior modification (BMOD) in a summer treatment program. Twenty-seven children with attention-deficit/hyperactivity disorder, aged 6-12, participated. Children received placebo and 3 doses of transdermal MPH (12.5 cm2, 25.0 cm2, and 37.5 cm2). BMOD was implemented on alternating weeks. Both treatments produced large and significant effects. Combined treatment was superior to either treatment alone. The effects of transdermal MPH were comparable to those found in this setting in previous studies with multiple stimulant medications and formulations. Consistent with other research, low doses of MPH--even lower than in previous studies--yielded enhanced effects in combination with behavior modification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)