Reaction to punishment, reflectivity, and passive avoidance learning in extraverts

Passive avoidance learning occupies a central role in accounts of disinhibited behavior, ranging from psychopaths' persistent criminality (Hare 1970) to extraverts' gregariousness (Gray, 1972). To explore the mechanism underlying passive avoidance deficits, we assessed the relation of extraversion, neuroticism, and response latency after punishment to passive avoidance learning by using two successive go/no go discrimination tasks. The tasks were designed to examine two aspects of subjects' reactions to punishment: response speed on trials immediately following punishment (Experiment 1) and time to terminate punishment feedback between successive trials (i.e., reflectivity; Experiment 2). Consistent with previous findings, the results of Experiment 1 showed that extraverts commit more passive avoidance errors than introverts do (Newman, Widom, & Nathan, 1985) and fail to pause following punished errors (Nichols & Newman, 1986). In Experiment 2, only neurotic extraverts displayed this pattern of performance differences. In both experiments, longer pausing following punishment predicted better learning from punishment for both introverts and extraverts. These results suggest that, in the presence of salient cues for reward, extraverts' characteristic reaction to punishment interferes with processing punished errors and may contribute to their more general propensity for impulsive, nonreflective action.     

Calcium channel antagonists enhance retention of passive avoidance and maze learning in mice

Although a number of studies have shown that treatment with calcium channel antagonists (CCAs) can ameliorate impairments in learning and memory in aged animals, evidence for a general nootropic effect of CCAs in neurologically normal young adult animals is ambiguous. This study attempts to resolve some of this ambiguity by comparing the effects of several CCAs on retention of passive avoidance learning and acquisition and retention of appetitively motivated spatial discrimination learning in young adult mice. Animals were trained in a step through passive avoidance apparatus and, immediately after training, injected subcutaneously with different doses of nimodipine, nifedipine, amlodipine, flunarazine, diltiazem, or verapamil. Retention was tested 24 h after training. In the maze-learning task mice were treated with the same doses of the aforementioned CCAs immediately after a brief training session in a linear maze and retention was tested 24 h after training. The most effective dose of each agent in the maze-retention experiment was administered to additional groups of animals 1 h prior to training to determine the effects of CCAs on acquisition processes. The effects of central administration of CCAs were examined by intracerebroventricular injection of different doses of amlodipine immediately after passive avoidance training. Results showed (1) all peripherally administered drugs except verapamil facilitated retention of passive avoidance training in a dose-dependent manner, (2) all drugs dose dependently facilitated retention of linear maze learning, (3) all doses of the drugs (except verapamil) which facilitated maze retention also facilitated maze learning, and (4) central administration of the dihydropyridine amlodipine produced a dose-dependent facilitation of the retention of passive avoidance learning. These data indicate that drugs which block calcium channels can enhance retention of two different types of learning in mice.     

Reduced lateralization in verbal dichotic listening in adolescent psychopaths

One possible explanation for previous findings of abnormal linguistic processing in psychopaths is that they are less lateralized for verbal processes. This study tests the hypothesis that adolescent psychopaths show evidence of reduced lateralization on a verbal dichotic listening task. Four self-report and behavioral measures of psychopathy were used to define psychopathy using cluster analytic techniques in 40 juvenile offenders aged 13 to 18 years. Psychopaths were found to have reduced ear asymmetries relative to nonpsychopaths, a result indicating reduced lateralization for verbal material. The effect does not appear to be mediated by group differences in age, ethnic background, IQ, overall performance, left-handedness, selective attention to one ear, or interhemispheric transfer deficits. This result suggests that the previous finding by Hare and McPherson is robust, provides some preliminary validity for the assessment of psychopathy before age 18, and indicates initial support for the utility of cluster analytic techniques in the assessment of psychopathy.     

Reversible disconnection of the hippocampal-prelimbic cortical circuit impairs spatial learning but not passive avoidance learning in rats

Wistar rats, treated with the GABA(A) receptor agonist muscimol, were used to investigate the role of the hippocampal-prelimbic cortical (Hip-PLC) circuit in spatial learning in the Morris water maze task, and in passive avoidance learning in the step-through task. In the water maze task, animals were trained for three consecutive days and tested 24 h after the end of training. In the step-through task, the animals were trained once and tested 24h after training. On the training days, daily infusion of muscimol (0.5 microg/0.25 microl) was given (1) bilaterally to the ventral hippocampus (vHip), (2) bilaterally to the prelimbic cortex (PLC), (3) to the unilateral vHip and the ipsilateral PLC, or (4) for disconnecting the Hip-PLC circuit, to both the unilateral vHip and the contralateral PLC 30 min before training. The results showed that inhibition of the vHip resulted in disruption of performance in both tasks. Inhibition of the PLC produced impaired water maze performance, but had no effect on the step-through task. Disconnection of the Hip-PLC circuit produced similar effects to PLC inhibition. However, simultaneous inhibition of the unilateral vHip and the ipsilateral PLC had little effect on performance of the water maze task. The results suggested that spatial learning depends on the Hip-PLC circuit, whereas passive avoidance learning is independent of this circuit.     

Carryover effects associated with the single-trial passive avoidance learning task in the young chick

The single-trial passive avoidance task is a useful procedure for examining learning and memory in the young chick. However, it has recently been suggested that discrepant results reported by different laboratories are due to differences in training procedure. The present study investigated a number of parameters surrounding the passive avoidance task, using day-old White Leghorn, Black Australorp cockerels. The results suggested that presentation of a water-dipped bead immediately after the aversive bead significantly altered retention levels. In addition, when the water-dipped bead was presented after the aversive bead, chicks failed to discriminate between beads for a period of 10 min following exposure to the aversant experience. A novel variant of the passive avoidance procedure, involving pretraining with a water-dipped red bead, training with an aversant-coated red bead, and testing with a dry red bead, was evaluated. A measure of avoidance was calculated using all three trials. It is suggested that the use of a single bead, measured both before and after the training experience and using both aversant- and water-trained controls, results in the most concise characterization of memory-related phenomena in the chick which is not contaminated by a carryover effect from the aversive training experience to the nonaversive bead.     

Reward dominance among children with disruptive behavior disorders

Investigated was a deficit in avoidance learning in situations of competing rewards and punishments in boys with behavior disorders. This learning style has been found to differentiate adults with psychopathy and controls and has been labeled reward dominance. The present study investigated the reward dominance paradigm in a group of 9- to 13-year-old boys with disruptive behavior disorders (N=21) and a normal control group (N=22). Subjects played four computer games programmed to provide the subject with a steadily decreasing ratio of rewards to punishments. Although the groups did not differ initially on the number of trials played, significant group differences emerged when measures of anxiety were included in the analysis. That is, boys with disruptive behavior disorders played more trials (reward dominance) only when the effect of anxiety was controlled. These findings are consistent with Gray's biobehavioral theory of personality and are also consistent with research indicating that anxiety is an important marker for a distinct subgroup of children with behavior problems.     

Stimulus selection in passive avoidance learning and retention: weanling, periadolescent, and young adult rats

Periadolescent rats exhibit a number of behavioral differences in comparison with younger or older animals. For instance, periadolescents tend to show enhanced acquisition of simple active avoidance tasks, but impaired acquisition of more complex appetitive and aversive discriminations. In this experiment, rats were trained on a simple passive avoidance task at one of three ages, as weanlings (25 days), periadolescents (35 days), or young adults (45 days). Training occurred in the presence of both a redundant discriminative stimulus and a specified, redundant contextual stimulus. The periadolescents did not differ from either younger or older rats in rate of learning the passive avoidance task. The retention performance of these animals was then tested following a change in either, neither, or both of the redundant cues. When a measure of performance that controls for baseline activity was used, it was observed that periadolescents were not disrupted by a change in the redundant discriminative stimulus, a cue change that clearly disrupted performance in 25- and 45-day-old animals, and tended to be more disrupted by the contextual change than younger or older rats. It is hypothesized that the alterations in performance exhibited by periadolescents may be related to an ontogenetic alteration in stimulus selection modulated by the catecholaminergic systems.     

Comparability of a single-trial passive avoidance learning task in the young chick across different laboratories

The discrepant results noted by the La Trobe/Monash, Sussex, Open, and Berkeley University memory research groups employing the passive avoidance task (PAT) with the chick indicate that some of these differences may be due to differences in training procedures between the various groups. The procedures employed by each group were replicated as closely as possible and compared using the same strain of chick. Higher levels of pecking and lower training latencies were observed in the La Trobe/Monash chicks. Improved training latency was observed following a change in the day of experimentation with Sussex chicks, and in white light in Open chicks. A powerful reinforcing effect was observed when pretraining was conducted with a wet lure across multiple pretraining trials, indicating the importance of this difference between groups. The observed impact on chick performance of these variables indicates that differences between PAT procedures may have important interactive effects with aversive learning. The results of data gathered using different procedures may only be superficially comparable, and further investigation of the effects of these variables is indicated.     

Temperament, executive functions, and the allocation of attention to punishment feedback in passive avoidance learning

Several theories have been proposed to account for the apparent non-responsiveness to punishment cues or aversive events demonstrated by members of some disinhibited groups. Included among these theories are those that emphasize individual differences in temperament, temperament-related biases associated with the allocation of attentional resources, and impairments in executive functions. This study examined the relative contribution of each of these variables to the prediction of passive avoidance errors (PAEs, or failures to inhibit responding to punishment cues) during a computerized go/no-go task. Variations in temperament, attentional allocation to punishment feedback, and executive functions were found to independently and additively contribute to the prediction of PAEs in a mixed sample of men and women recruited at a university campus (n=145). Results from this study, therefore, support multiple theoretical perspectives on PAEs as assessed by the go/no-go experimental paradigm.     

One-trial-a-day avoidance learning

A one-trial-a-day discrete-trial avoidance conditioning procedure run for 30 consecutive days was compared with a massed-trial procedure where Ss received 30 consecutive trials within 1 day. The Ss in both groups were equated for time each S spent in the nonshock compartment of the apparatus, number of times the transport box carrying Ss was lifted out of the nonshock compartment, and the number of times each S was handled. The main difference between groups was the intersession trial length of 24 h for the one-trial-a-day Ss. Learning was rapid for both groups. The groups did not differ reliably on six acquisition indices. The methodological advantages of the one-trial-a-day procedure and its theoretical importance were discussed.     

Effects of combined treatment with vitamins C and E on passive avoidance learning and memory in diabetic rats

Learning and memory deficits occur in diabetes mellitus. Although the pathogenesis of cognitive impairment in diabetes has not been fully elucidated, factors such as metabolic impairments, vascular complications and oxidative stress are thought to play possible roles. Here we investigated the effect of chronic treatment with vitamin C (50 mg/kg, p.o), vitamin E (100 mg/kg, p.o) and both together on passive avoidance learning (PAL) and memory in male Wistar control and diabetic rats. Treatments were begun at the onset of hyperglycemia. Passive avoidance learning was assessed 30 days later. Retention was tested 24 h after training. At the end, animals were weighed and blood samples were drawn for plasma glucose measurement. Diabetes caused impairment in acquisition and retrieval processes of PAL and memory. The combination of vitamin C and E improved learning and memory in controls and reversed learning and memory deficits in diabetic rats. Combined treatment also affected the body weight and plasma glucose level of diabetic treated animals compared to untreated diabetic animals. Hypoglycemic effects and antioxidant properties of the vitamins may be involved in the nootropic effect of such treatment. These results show that combined treatment with vitamins C and E improved PAL and memory of control rats. In addition, combined vitamins administration to rats for 30 days from onset of diabetes alleviated the negative influence of diabetes on learning and memory. Therefore, combined vitamins treatment may provide a new potential alternative for prevention of impaired cognitive functions associated with diabetes and may warrant further clinical study.     

Limbic networks and associative learning: II. Entorhinal contributions to spontaneous alternation, passive avoidance, and taste aversion learning

The hippocampus plays an important role in learning and memory, but the precise nature of that involvement remains uncertain. Transection of the perforant path, a primary input pathway to the hippocampus, has been shown to produce changes in reaction to novelty and acquisition of active avoidance; the nature and magnitude of these changes vary with lateral or medial perforant path damage. In a series of experiments on adult rats, the role of these pathways in spontaneous alternation, exploration, acquisition and extinction of conditioned responses, passive avoidance, and conditioned taste aversion was investigated. Lateral transection reduced exploration while medial transection facilitated acquisition of an active avoidance response; no effects were observed on any other measure. Results are discussed in terms of what perforant path damage might reveal regarding the interactions of the hippocampus with other brain regions.     

Limbic networks and associative learning: II. Entorhinal contributions to spontaneous alternation,passive avoidance,and taste aversion learning

The hippocampus plays an important role in learning and memory, but the precise nature of that involvement remains uncertain. Transection of the perforant path, a primary input pathway to the hippocampus, has been shown to produce changes in reaction to novelty and acquisition of active avoidance; the nature and magnitude of these changes vary with lateral or medial perforant path damage. In a series of experiments on adult rats, the role of these pathways in spontaneous alternation, exploration, acquisition and extinction of conditioned responses, passive avoidance, and conditioned taste aversion was investigated. Lateral transection reduced exploration while medial transection facilitated acquisition of an active avoidance response; no effects were observed on any other measure. Results are discussed in terms of what perforant path damage might reveal regarding the interactions of the hippocampus with other brain regions.     

The Self-Report Psychopathy Scale and passive avoidance learning: a validation study of race and gender effects

The reliability and validity of the Self-Report Psychopathy Scale (SRPS) was examined in a noninstitutionalized offender sample of mixed gender and race. Adequate alpha coefficients were obtained for the total sample and across gender and race. The SRPS was compared to measures of trait anxiety and passive avoidance errors. SRPS total, primary, and secondary scores were positively and significantly correlated with trait anxiety and passive avoidance (commission) errors, but not omission errors. Employing hierarchical regression models, no anxiety, gender, or ethnic effects were found. Intelligence confounded the relationship between psychopathic traits and passive avoidance errors. Findings provide tentative support of the SRPS as a valid measure of psychopathy.