Learning in the intact cockroach (Periplaneta americana) when placed in a punishment situation.

Examined whether 40 intact cockroaches, Periplaneta americana, in a yoked-control punishment paradigm exhibit escape or avoidance learning, or both. Evidence for avoidance learning was unequivocal. Escape learning was not found. Asymptotic avoidance learning was found by 1.5 min. of training. The advantages of defining learning by experimental-control differences developing during training are discussed. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Aversive conditioning in neonatal kittens.

Trained 45 kittens less than 10 days of age to crawl over a barrier in a 1-way shuttle box either to escape or avoid pressurized air. Both instrumental escape and avoidance learning occurred. Escape performance was an increasing negatively accelerated function of air pressure. Avoidance behavior was not as stable or of the same form as that previously observed in infant dogs. (15 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioning and extinction of avoidance and escape behavior in neonatal dogs.

Ran 16 neonatal purebred beagles for 6.5 days in a 1-way shuttle box with cold air as the aversive stimulus. 8 Ss started at 1 day of age and 4 each started at 2 and 3 days of age. 8 Ss received escape conditioning and 8 received avoidance conditioning. Following this training, both groups were given a series of extinction trials. Both escape and avoidance conditioning and extinction were obtained. Findings are comparable to previous avoidance findings in neonatal dogs and superior to findings on neonatal mice and kittens. Results display quantitative properties found in studies of adult rats and especially adult dogs. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Species differences in ontogeny of memory: Indirect support for neural maturation as a determinant of forgetting.

Studied the development of long-term memory in 150 Sprague-Dawley rats and 80 male Hartley guinea pigs as a function of age, using active escape and passive avoidance tasks. Memory increased with age in the rats but did not change in the guinea pigs. It is concluded that neurological maturity at the time of original learning appears to be a major determinant of long-term memory. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Schizophrenic discrimination learning as a function of aversive social and physical reinforcement.

60 schizophrenics comparable in important psychopathological variables (e.g., Inpatient Multidimensional Psychiatric Rating Scale and the Premorbid History-Phillips Prognostic Rating Scale) to Ss in other similar studies were compared on a discrimination learning task with noxious physical reinforcement (intense white noise at 91–94 db) under experimenter (E)-present conditions with motivational instructions and E-absent conditions with neutral instructions. Aversive reinforcement was delivered on a response contingent basis for avoidance and escape training under both social conditions. Long-term effects were evaluated 3 consecutive learning tasks: before, during, and following the 6 reinforcement conditions. Results provide strong confirmation that social factors in the E–S relationship determine the speed of learning throughout. Regardless of physical punishment or the reinforcement paradigm (avoidance or escape), Ss learned significantly faster in the E's presence with motivational instructions both during and after the reinforcement phase. The theoretical implications of what is called biological motivation were found to be insufficient grounds for ordering the data. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny and interdependence of genetically selected behaviors in rats: Avoidance response and open field.

Investigated in 2 experiments, ontogeny and interdependence of genetically selected avoidance and open-field behaviors in 6 genetic lines (e.g., MNR/Har/Lu, RCA/Lu), involving 1,018 rats, and 3 developmental models (longitudinal, cross-sectional, and generational). In selected lines, behaviors varied with age (either 21-, 35-, 70-, or 100 days of age), depending upon the genetic selection; in the control (random bred) line, no such effects were found. Between the lines selected for high (RHA) and low (RLA) rates of 2-way active avoidance, ontogenetic differences in the selected behavior emerged as Ss grew older, whereas between the lines selected for high (MR) and low (MNR) frequency of open-field defecation, the differences in the selected behavior were present at all stages of development. In Ss' unconditioned escape response to footshock, the differences were present at all stages. The relationship between avoidance response and open-field defecation (emotional reactivity) was not linear but suggestive of a curvilinear inverted-–U function. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The opioid/nonopioid nature of stress-induced analgesia and learned helplessness.

Investigated whether the same factors that activate the processes that produce escape interference might also activate processes leading to opioid stress-induced analgesia (SIA). Exposure to a variety of stressors produces a subsequent analgesic reaction that is sometimes opioid in nature (reversed by opiate antagonists and cross-tolerant with morphine) and sometimes nonopioid. In Exp I, 40 male albino rats were subjected to 20 min of intermittent footshock, 3 min of continuous footshock, tailshock on a VI schedule, or confinement only. Ss were given escape/avoidance training 24 hrs later. In Exp II, 36 Ss received SIA with a tail-flick apparatus. In Exp III, 40 Ss received inescapable tailshocks or confinement only. In Exp IV, 24 Ss received 2 sessions of footshock before tail-flick was assessed. Both of the opioids SIA procedures produced a learned helplessness effect as assessed by shuttlebox escape acquisition and an analgesia that was reinstatable 24 hrs later. The nonopioid procedures produced neither a learned helplessness effect nor a reinstatable analgesia. These data implicate the learning of uncontrollability in the activation of opioid systems. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Undernutrition by rearing in large litters delays the development of reflexive, locomotor, and memory processes in mice.

In 3 experiments with a total of 512 Swiss-Webster mice, the effects of early postnatal undernutrition on the ontogeny of several behavioral capacities of varying complexity were investigated. After birth, mouse pups in all experiments were reared in either normally nourished or undernourished conditions by maintaining litter sizes at 6 or 16, respectively. Exps I and II examined the development of adultlike patterns of swimming behaviors and spontaneous locomotor activity, respectively, as a function of litter size. The maturation of both behavior patterns was delayed by about 2 days in the 16-litter mice. In Exp III, normally-nourished and undernourished Ss received 25 trials in a shock–escape T-maze at 9, 11, and 13 days of age, followed by similar retention tests 24 hrs later. Although litter size had little effect on correct turns at each age during training, Ss reared in litters of 6 showed significant retention of prior training by 12 days of age, whereas comparable retention was not noted for the large litter mice until 14 days of age. Results suggest that nutritional deficits, imposed by rearing in large litters during the postnatal period of rapid CNS maturation, retard the development of behavioral capacities involving both unlearned and learned responses. (40 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory of rats with amygdala lesions induced 30 days after footshock-motivated escape training reflects degree of original training.

This experiment was conducted to determine whether the amount of preoperative training influences the effects, on retention, of amygdala lesions induced 30 days after escape training. Rats received 1 or 10 footshock-motivated escape training trials; 30 days later, sham or neurotoxic amygdala lesions were induced. Results of an inhibitory avoidance test performed 4 days after surgery indicated that amygdala lesions impaired retention performance; however, increased preoperative training partially attenuated the retention deficit. Increased preoperative training also attenuated the impairing effects of the lesions on retention assessed in a continuous multiple-trial inhibitory avoidance task given 36 days after the original escape training. The finding that amygdala-lesioned rats remembered the escape training suggests that the amygdala is not a critical locus of the changes underlying the long-term retention of footshock-motivated escape training. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Resympathectomy for palmar and axillary hyperhidrosis

BACKGROUND: The aim was to analyse patterns of failure or symptom recurrence after primary sympathectomy for palmar or axillary hyperhidrosis, and to carry out tactical problem-solving for resympathectomy and review the operative findings. METHODS: Over a 2-year period, 20 patients (six men and 14 women) underwent resympathectomy for palmar hyperhidrosis (13 patients, 20 sides) or axillary hyperhidrosis (seven patients, ten sides). T2-3 sympathectomy for palmar hyperhidrosis or T4-5 sympathectomy for axillary hyperhidrosis was performed during the repeat procedure. Criteria for evaluation by means of patient questionnaire included good (more than 80 per cent), fair (50-80 per cent) and poor (less than 50 per cent) improvement. RESULTS: Operative findings included inadequate sympathectomy on 19 sides, nerve regeneration on eight sides and no evidence of previous sympathectomy on three sides. One patient had Kuntz fibre in addition to inadequate sympathectomy. In the palmar hyperhidrosis group, good results were obtained in all 13 patients on all 20 sides after resympathectomy. In the axillary hyperhidrosis group, six of seven patients, or eight of ten sides, showed good results after resympathectomy. CONCLUSION: The main cause of primary sympathectomy failure was inadequate surgery, and recurrence of palmar or axillary hyperhidrosis was seldom caused by nerve regeneration. The key factor for preventing failed sympathectomy or recurrent palmar or axillary hyperhidrosis is a first-time sympathectomy that is both accurate and adequate. Most patients with recurrent symptoms can be cured by resympathectomy.     

Reinforcement versus species-specific defense reactions as determinants of avoidance barpressing.

In three experiments, rats whose escape and avoidance barpresses were reinforced by entering a safe floor in an otherwise shuttle conditioning arrangement (a shuttle barpress task) showed better learning than the rats that did not receive such reinforcement only when the shock intensity was very weak. Barpresses were found to have mostly nonfrontal topography and appeared not to be under the control of escape or avoidance contingency of reinforcement. Preavoidance training in which only frontal barpresses were allowed to terminate shock greatly facilitated avoidance responding and nullified the inverse effect of shock intensity. The findings were interpreted as indicating that innate defensive reactions play a more prominent role in avoidance behavior than reinforcement, but they do not appear to be as fixed and unmodifiable by learning as often suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Infarct topography and hemiparesis profiles with cerebral convexity infarction: the Stroke Data Bank

The development of natural killer (NK) cell activity was assessed in Fischer 344 (F344) rats sympathectomized as neonates with the neurotoxin, 6-hydroxydopamine (6-OHDA). No NK cell activity was detected in sympathectomized or vehicle-injected control animals at 7 days of age. At 10 and 14 days of age, NK cell activity was reduced in spleens from sympathectomized male and female rats. At 21 days of age, a reduction in NK cell activity was detected only in sympathectomized male rats. Sympathectomy did not alter NK cell activity at 28 and 42 days of age in either gender. At 56 days of age, NK cell activity was increased in neonatally sympathectomized females; rats of both genders acutely sympathectomized at 56 days of age also showed enhanced NK cell activity. No differences were observed at 90 days of age in neonatally or acutely sympathectomized males of females. Prior treatment with desipramine, which blocks uptake of 6-OHDA into nerve terminals and prevents the destruction of sympathetic nerve terminals, prevented these 6-OHDA-induced effects, suggesting that sympathectomy, and not direct toxic effects of 6-OHDA treatment of NK cells, accounted for the alterations in NK cell activity. Together, these results indicate that the sympathetic nervous system is an integral component of the developing lymphoid and hematopoietic microenvironment.     

Genetic differences in avoidance learning by Rattus norvegicus: Escape/avoidance responding, sensitivity to electric shock, discrimination learning, and open-field behavior.

Studied the behaviors of Long-Evans rats selectively bred for either good (SHA line) or poor (SLA line) shuttle box avoidance learning. The results of Exp I indicated that the phenotypic difference in avoidance learning was not associated with differences in speed of escape or avoidance responding. Differences between the lines in frequency of intertrial responses (ITRs), which appeared during training but not during pretest, suggest that ITRs in Ss of the low-avoidance SLA line were more suppressed by electric shock than in Ss of the high-avoidance SHA line. This result suggests that SLA Ss may be more emotionally responsive than SHA Ss. Exp II demonstrated that the Ss of the 2 lines did not differ in absolute sensitivity to electric shock, and Exp III showed that the poor performance of the SLA line was not due to an inability to learn. Ss also provided evidence that the poor avoidance learning by SLA Ss was due to their emotional reactivity. Observations of open-field behavior in Exp IV were consistent with this hypothesis. It is concluded that the major consistent correlate of the phenotypic difference in avoidance learning was greater emotionality or emotional reactivity in SLA than in SHA Ss. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of pretraining compatible and incompatible responses on subsequent one-way and shuttle-avoidance performance in rats.

Conducted 6 experiments with male Holtzman rats. A single noncontingent footshock was found to facilitate subsequent one-way and shuttle avoidance if the CS in preshock and avoidance training was the same. If the to-be-established instrumental response was punished during preshock, or if Ss were required to run toward the CS paired with shock during pretraining, the facilitative effects of preshock were eliminated. Facilitation by a single preshock was not enhanced if shock was escapable, regardless of the CSs, task, or whether escape was immediate or delayed. If Ss received 10 one-way escape trials, the beneficial effects of preshock on one-way and shuttle avoidance were enhanced. In contrast, shuttle-escape training produced no such beneficial effects on avoidance performance. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mortality differences between men and women following first myocardial infarction. RESCATE Investigators. Recursos Empleados en el Síndrome Coronario Agudo y Tiempo de Espera

CONTEXT: Mortality after acute myocardial infarction is worse in women than in men, even after adjustment for comorbidity and age dissimilarities between sexes. OBJECTIVE: To assess the influence of sex on survival after acute myocardial infarction. DESIGN: Inception cohort obtained in a prospective registry of patients with acute myocardial infarction from 1992 through 1994. SETTING: Four teaching hospitals in northeastern Spain. PATIENTS: All consecutive patients aged 80 years or younger with first acute myocardial infarction. A total of 331 women and 1129 men were included. MAIN OUTCOME MEASURE: Survival at 28 days and mortality or readmission at 6 months. RESULTS: Women were older (mean, 68.6 vs 60.1 years), presented more often with diabetes (52.9% vs 23.3%), hypertension (63.9% vs 42.3%), or previous angina (44.6% vs 37.4%), and developed more severe myocardial infarctions than men (acute pulmonary edema or cardiogenic shock occurred in 24.8% of women and 10.5% of men) (all P<.02). Men were more likely than women to receive thrombolytic therapy (41.3% vs 23.9%; P<.001), but rates of percutaneous transluminal angioplasty and coronary artery bypass graft surgery at 28 days were similar among men and women. The 28-day mortality rate was significantly higher among women (18.5% for women, 8.3% for men; P<.001). Revascularization procedures at 6 months were performed in a similar proportion of women and men. However, women had higher 6-month mortality rates (25.8% in women, 10.8% in men; P<.001) and readmission rates (23.3% for women, 12.2% for men; P<.001). After adjustment, women had greater risk of death than men at 28 days (odds ratio [OR], 1.72; 95% confidence interval [CI], 1.12-2.65) and at 6 months (OR, 1.73; 95% CI, 1.18-2.52). CONCLUSIONS: In this study population, women experienced more lethal and severe first acute myocardial infarction than men, regardless of comorbidity, age, or previous angina.     

Genotype-dependent effects of septal lesions on different types of learning in the mouse.

Tested 80 C57BL/6J, DBA/2J, and SEC/1ReJ mice with septal or control lesions for exploratory behavior, shuttle-box avoidance learning, discriminated avoidance, and maze-learning ability. Control DBA and SEC Ss normally displayed low levels of exploratory behavior and efficient avoidance and maze learning. High exploratory activity and low avoidance and maze learning were characteristically shown by C57 controls. All strains with septal lesions increased levels of exploratory and avoidance behaviors. In contrast, following septal lesions the 3 strains performed more poorly in discriminated-avoidance and maze learning. It is concluded that differences in septal function-e.g., in level of response inhibition-do not substantially account for the learning differences evident between these strains. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related deficits in acquisition of a passive avoidance response.

In Exp. I, 80 male albino rats 10, 15, 20, 30, or 100 days old received a brief inescapable shock contingent upon making a step-off response. Step-off latencies increased for all age groups, but rate of learning was significantly faster in older Ss. Learning appeared to be based primarily upon punishment effects rather than general emotionality, since yoked Ss shocked after being placed directly on the grids did not acquire the avoidance response. Exp. II with 120 Ss employed 3 training conditions with independent groups 12, 15, 18, or 21 days old. The step-off response resulted in shock that was either: (a) escapable; (b) inescapable, 1-sec duration; or (c) inescapable, yoked duration. Younger Ss were again significantly inferior to more mature Ss. Escapable shock improved acquisition at 2 age levels, but the effect appeared to be more related to shock duration than to the response contingency. It is suggested that the requirement of withholding a punished response may represent a category of learning that is especially sensitive to maturational changes. (French summary) (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental model of acute encephalopathy after total body irradiation in the rat: effect of liposome-entrapped Cu/Zn superoxide dismutase

PURPOSE: To develop an experimental model of acute encephalopathy following total body irradiation in rats and to define the therapeutic effect of liposome-entrapped Cu/Zn superoxide dismutase. METHODS AND MATERIALS: A total of 120 4-month-old rats received 4.5 Gy total body irradiation (TBI) while 120 rats received sham irradiation. A behavioral study based on a conditioning test of negative reinforcement, the one-way avoidance test, was performed 5 hours before irradiation and repeated the following days. Subcutaneous treatment was started 1 hour after irradiation and repeated daily for 2 weeks. In both the irradiated and sham group, three subgroups were defined according to the treatment received: liposome-entrapped Cu/Zn superoxide dismutase (0.5 mg/kg), liposomes only, normal saline. RESULTS: This work comprised two consecutive studies. In study A (90 rats) the one-way avoidance test was administered daily from day 0 to day 4 with a recall session at day 14. In study B (validation phase in 150 rats) the behavioral test was performed only from day 0 to day 6. Before irradiation, all rats showed a similar behavioral response. Study A (6 groups of 15 rats): Following TBI, irradiated rats treated with liposomes only or saline demonstrated a significant delay in learning the one-way avoidance test in comparison with sham-irradiated rats (0.05 < p <0.001 depending upon the day of evaluation and the subgroup type). In contrast, irradiated rats treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from sham-irradiated rats. Study B (6 groups of 25 rats): The results were the same as those in study A, demonstrating a significant delay in the learning of the test in the liposome and saline-treated irradiated rats in comparison with sham-irradiated rats (0.02 < p < 0.001). The irradiated rats, treated with liposome-entrapped Cu/Zn superoxide dismutase did not differ from the sham-irradiated controls. CONCLUSION: This study indicates that a relatively low dose of total body irradiation induces a substantial acute learning dysfunction in the rat. This effect is prevented by the administration of liposome-entrapped Cu/Zn superoxide dismutase.     

Correlations between paradoxical sleep and shuttle-box conditioning in rats.

Eighteen male Wistar rats were given one daily two-way active avoidance conditioning session followed immediately by 5 hr of sleep recording, for 5 consecutive days. The group of rats that achieved 80% or greater avoidance in some of the 5 training sessions showed significant linear increases of paradoxical sleep (PS), compared with baseline levels, throughout the successive conditioning sessions. Furthermore, (a) the group of rats showing PS increases (more than 1 SD above baseline) after some of the training sessions achieved a significantly higher final number of avoidances than the remaining animals; (b) a high and positive correlation was observed between avoidance increases in the 3rd conditioning session and previous PS; and (c) maximum increases in correct performance often occurred following PS increases. It is concluded that PS increases facilitate the consolidation of learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of surgical sympathectomy on skin blood flow in a rat model of chronic limb ischemia

The role of lumbar sympathectomy in the treatment of limb ischemia secondary to arteriosclerosis obliterans has been controversial. Increased temperature and rubor of the skin, which usually follow sympathectomy, have generally been interpreted as indicative of improved nutritive skin blood flow. However, the existence of a (nonnutritive) thermoregulatory level of skin microcirculation makes such an extrapolation questionable. We investigated the total (mainly thermoregulatory) skin blood flow (TSBF) in the hindlimb of 15 male Lewis rats by means of laser Doppler flowmetry and the nutritive skin blood flow (NSBF) by means of capillary microscopy (red blood cell velocity). Transcutaneous oximetry was used to assess skin oxygenation (SO). Measurements were performed before and 2 and 28 days after ligation of the common iliac and iliolumbar artery. Subsequently, either a surgical resection of the sympathetic chain (L2-L6) was performed or a sham operation. Measurements were repeated 2 and 28 days later. For the group of 15 rats as a whole, TSBF (p < 0.05), NSBF (p < 0.05), and SO (p < 0.05) were found to be drastically reduced at day 2 after litigation compared to preligation values. This reduction partially recovered during the following weeks. TSBF (p < 0.05) and NSBF (p < 0.05), however were still reduced at day 28 after ligation compared to preligation values, whereas the SO at this time tended to be lower (p = 0.11). In the sympathectomy group the TSBF was found to be increased at day 2 (p < 0.05) and day 28 (p < 0.05) after sympathectomy, both compared to values obtained at day 28 after ligation. Sympathectomy did not have an effect on NSFB and SO. The sham procedure had no effect on the TSBF, NSBF, or SO. These results indicate that in case of lower limb ischemia, sympathectomy improves skin blood flow at the thermoregulatory but not the nutritive level of skin microcirculation. This may be related to the fact that the thermoregulatory vessels are mainly sympathetically controlled, whereas the nutritive capillaries are mainly controlled by local (nonneural) factors.