Summation of reinforcement rates when conditioned stimuli are presented in compound

Three experiments used delay conditioning of magazine approach in rats to examine the summation of responding when two conditioned stimuli (CSs) are presented together as a compound. The duration of each CS varied randomly from trial-to-trial around a mean that differed between the CSs. This meant that the rats' response rate to each CS was systematically related to the reinforcement rate of that CS, but remained steady as time elapsed during the CS (Harris & Carpenter, 2011; Harris, Gharaei, & Pincham, 2011). When the rats were presented with a compound of two CSs that had been conditioned separately, they responded more during the compound than during either of the CSs individually. More significantly, however, in all three experiments, the rats responded to the compound at the same rate as they responded to a third CS that had been reinforced at a rate equal to the sum of the reinforcement rates of the two CSs in compound. We discuss the implications of this finding for associative models (e.g., Rescorla & Wagner, 1972) and rate-based models (Gallistel & Gibbon, 2000) of conditioning.     

Unequal associative changes when excitors and neutral stimuli are conditioned in compound

In four experiments a compound of a previously conditioned excitor and a neutral stimulus was either reinforced with food or nonreinforced. Two experiments used a magazine approach procedure in rats, and two used an autoshaping procedure in pigeons. All experiments employed a novel compound test procedure, which permitted evaluation of the size of the associative change that took place for the excitatory and neutral stimuli. Reinforcement of the compound resulted in greater increments in the associative strength of the neutral stimulus than of the excitor. Nonreinforcement of the compound resulted in greater decrements in the associative strength of the excitor than of the neutral stimulus. These results agree with earlier experiments with compounds of excitors and inhibitors and provide an additional challenge to contemporary error-correction models of conditioning.     

Blocking of inhibitory conditioning within a serial conditioned stimulus-conditioned inhibitor compound: Maintenance of acquired behavior without an unconditioned stimulus

Well-trained classically conditioned stimuli, presented unreinforced, were protected from extinction when they were followed by a signal of the omission of the reinforcer (conditioned inhibitor Konorskian type) in eight cats. An aversive classical conditioning paradigm with shock as the reinforcer was used. Of several behavioral (leg flexion, vocalization) and organismic arousal (heart rate, respiration rate, respiration amplitude) measures of conditioned responses, the respiration amplitude changes were found to be most informative for the continuous assessment of elicited arousal of low and medium intensity. In all subjects conditioned stimuli presented during extinction in serial compound with the conditioned inhibitor elicited larger responses than did conditioned stimuli presented alone during extinction. The mechanism of protection from extinction in a paradigm in which the elicitor of learned behavior occurs prior to the conditioned inhibitor provides the organism with the mechanism for the maintenance of learned behavior in the absence of a reinforcer.     

Blockade of GABAA receptors in the interpositus nucleus modulates expression of conditioned excitation but not conditioned inhibition of the eyeblink response

The cerebellum and related brainstem structures are essential for excitatory eyeblink conditioning. Recent evidence indicates that the cerebellar interpositus and lateral pontine nuclei may also play critical roles in conditioned inhibition (CI) of the eyeblink response. The current study examined the role of GABAergic inhibition of the interpositus nucleus in retention of CI. Male Long-Evans rats were implanted with a cannula positioned just above or in the anterior interpositus nucleus before training. The rats were trained with two different tones and a light as conditioned stimuli, and a periorbital shock as the unconditioned stimulus. CI training consisted of four phases: 1) excitatory conditioning (8 kHz tone paired with shock); 2) feature-negative discrimination (2 kHz tone paired with shock or 2 kHz tone concurrent with light); 3) summation test (8 kHz tone or 8 kHz tone concurrent with light); and 4) retardation test (light paired with shock) After reaching a criterion level of performance on the feature-negative discrimination (40% discrimination), 0.5 μl picrotoxin (a GABA_A receptor antagonist) was infused at one of four concentrations, each concentration infused during separte test sessions. Picrotoxin transiently impaired conditioned responses during trials with the excitatory stimulus (tone) in a dose-dependent manner, but did not significantly impact responding to the inhibitory compound stimulus (tone-light). The results suggest that expression of conditioned inhibition of the eyeblink conditioned response does not require GABAergic inhibition of neurons in the anterior interpositus nucleus.     

An action sequence held in memory can interfere with response selection of a target stimulus,but does not interfere with response activation of noise stimuli

Withholding an action plan in memory for later execution can delay execution of another action if the actions share a similar (compatible) action feature (e.g., response hand). We investigated whether this phenomenon, termed compatibility interference (CI), occurs for responses associated with a target as well as responses associated with distractors in a visual selection task. Participants planned and withheld a sequence of keypress responses (with their right or left hand), according to the identity of a stimulus (A), and then immediately executed a keypress response (with their right or left hand) to a second stimulus (B), according to the identity of a target letter appearing alone or among distractor letters. Distractor letters were either response compatible or incompatible with the target and appeared either simultaneously with the target (Experiments 1A and 2) or 100 msec before the target (Experiment 1B). Also, stimulus-response mapping was either 1:1 (Experiment 1) or 2:1 (Experiment 2). Results showed that the response to the Stimulus B target was delayed when it required the same response hand as Stimulus A, as opposed to a different hand. Also, the target reaction time for Stimulus B was greater when the target was flanked by incompatible distractors than when it was flanked by compatible distractors. Moreover, the degree of CI was consistent across the compatible-, incompatible-, and no-distractor conditions, indicating that CI generalizes to responses associated with a target, but not to those associated with distractors. Thus, CI occurs at a response selection, not at a response activation stage. Implications for the code occupation account for CI (e.g., Stoet & Hommel, 1999, 2002) and an alternative account for CI are discussed.     

Amnesia produced by anisomycin in an appetitive task is not due to conditioned aversion

Two experiments investigated the effects of lithium chloride (LiCl) and anisomycin (ANI) in a water reward Y-maze task. In Experiment 1, male CD-1 mice given weak or strong training were injected post-training with either saline or LiCl (150 mg/kg), which has been reported to produce conditioned aversion in mice. One day after training, both LiCl groups avoided the rewarded arm of the maze and drank less water than saline-injected controls. Two days after training, the strongly trained LiCl mice showed avoidance, while both LiCl groups drank less water. In Experiment 2, weakly trained mice given pre- and post-training ANI (30 mg/kg) were amnesic on the second test day compared to mice that received post-trial saline. However, water consumption was increased on the test day for both groups. LiCl produced a different pattern of results than ANI in this task. On the basis of these results, it is suggested that amnesia produced by ANI is due to impaired memory formation and not to conditioned aversion.     

Rho-associated kinase in the gustatory cortex is involved in conditioned taste aversion memory formation but not in memory retrieval or relearning

Rho-associated kinase (ROCK) is intimately involved in cortical neuronal morphogenesis. The present study explores the roles of ROCK in conditioned taste aversion (CTA) memory formation in gustatory cortex (GC) in adult rat. Microinjection of the ROCK inhibitor Y-27632 into the GC 30 min before CTA training or 10 min after the conditioned stimulus (CS) impaired long-term CTA memory (LTM) formation. ROCK inhibitor had no effect on taste aversion when injected before the first LTM test day and did not alter taste aversion on subsequent test days. Microinjection of ROCK inhibitor into GC 30 min before preexposure to the taste CS had no effect on latent inhibition of CTA learning suggesting that ROCK is involved in CS-US association rather than taste learning per se. Cumulatively, these results show that ROCK is needed for normal CTA memory formation but not retrieval, relearning or incidental taste learning.     

The antiemetic drug ondansetron interferes with lithium-induced conditioned rejection reactions, but not lithium-induced taste avoidance in rats

Conditioned rejection reactions displayed in the taste reactivity test are exclusively produced by treatments that elicit nausea. The present experiments demonstrate that pretreatment with the antinausea agent ondansetron interferes with both the establishment and the expression of conditioned rejection reactions. Ondansetron did not interfere with lithium-induced taste avoidance in either a 1-bottle or a 2-bottle test. In fact, when rejection reactions were measured during a consumption test, ondansetron selectively attenuated rejection reactions, with only a slight modification of consumption. These results suggest that conditioned rejection reactions, but not conditioned taste avoidance, reflect nausea in rats that can be attenuated by ondansetron pretreatment.     

Long-term potentiation in the dentate gyrus in freely moving rats is reinforced by intraventricular application of norepinephrine, but not oxotremorine

Growing evidence suggests that processes of synaptic plasticity, such as long-term potentiation (LTP) occurring in one synaptic population, can be modulated by consolidating afferents from other brain structures. We have previously shown that an early-LTP lasting less than 4 h (E-LTP) in the dentate gyrus can be prolonged by stimulating the basolateral amygdala, the septum or the locus coeruleus within a specific time window. Pharmacological experiments have suggested that noradregeneric (NE) and/or cholinergic systems might be involved in these effects. We have therefore investigated whether the direct intraventricular application of agonists for NE- or muscarinic receptors is able to modulate synaptic plasticity. E-LTP was induced at the dentate gyrus of freely moving rats using a mild tetanization protocol that induces only an E-LTP. NE or oxotremorine (OXO) were applied icv 10 min after the tetanus. Results show that low doses of NE (1.5 and 5 nM) effectively prolong LTP. A higher dose (50 nM) was not effective. None of the OXO doses employed (5, 25, and 50 nM) showed similar effects. These results stress the importance of transmitter-specific modulatory influences on the time course of synaptic plasticity, in particular NE whose application mimics the reinforcing effect of directly stimulating limbic structures on LTP.     

Alexithymia is associated with an augmenter profile, but not only: Evidence for anticipation to arousing music

Grynberg, D., Davydov, D. M., Vermeulen, N. & Luminet, O. (2012). Alexithymia is associated with an augmenter profile, but not only: Evidence for anticipation to arousing music. Scandinavian Journal of Psychology 53, 375-381. It has been suggested that high alexithymia scorers have an 'augmenter' profile which amplifies their physiological and subjective responses to highly arousing stimuli. The aim of this study was to test this theory using several physiological measures. Participants listened to musical excerpts either in a 'weak-to-strong' or a 'strong-to-weak' order of arousing levels of stimuli. The results show that alexithymia was associated with an augmenter profile for subjective reports for the most arousing stimulus and with stronger skin conductance level responses in the 'strong-to-weak' order. These results partially support the augmenter profile and reveal that alexithymia may be associated with higher anticipation for the most arousing excerpt.     

Equality in hiring permanent resident foreign nationals in the United States: when loyalty is the question, but not the issue

Permanent resident foreign nationals, who have been legally admitted to the United States, have the right to work. However, when deciding the constitutionality of a state statute that requires citizenship for a public domain job, the rights of permanent residents to seek gainful employment are balanced against the rights of state governments to ensure that important sovereign functions are entrusted only to their citizens. Several important Supreme Court decisions have been 5/4 split decisions because of this tension and dissenting judges have countered that the majority rulings were based on presumptions, and not facts, that citizens are more loyal than permanent residents. The judges have also disagreed about the level, within a civil service hierarchy, below which a citizenship requirement is unconstitutional. This article reviews United States court decisions for relevant issues and solutions, and shows how empirical studies in the area of human resource management can help resolve the issues that have caused the dissent. The analysis will be useful to legal and human resource professionals in the U.S. and other countries affected by surging global migration.     

Circulating fibrinogen but not D-dimer level is associated with vital exhaustion in school teachers

Meta-analyses have established elevated fibrinogen and D-dimer levels in the circulation as biological risk factors for the development and progression of coronary artery disease (CAD). Here, we investigated whether vital exhaustion (VE), a known psychosocial risk factor for CAD, is associated with fibrinogen and D-dimer levels in a sample of apparently healthy school teachers. The teaching profession has been proposed as a potentially high stressful occupation due to enhanced psychosocial stress at the workplace. Plasma fibrinogen and D-dimer levels were measured in 150 middle-aged male and female teachers derived from the first year of the Trier-Teacher-Stress-Study. Log-transformed levels were analyzed using linear regression. Results yielded a significant association between VE and fibrinogen (p = 0.02) but not D-dimer controlling for relevant covariates. Further investigation of possible interaction effects resulted in a significant association between fibrinogen and the interaction term "VE x gender" (p = 0.05). In a secondary analysis, we reran linear regression models for males and females separately. Gender-specific results revealed that the association between fibrinogen and VE remained significant in males but not females. In sum, the present data support the notion that fibrinogen levels are positively related to VE. Elevated fibrinogen might be one biological pathway by which chronic work stress may impact on teachers' cardiovascular health in the long run.     

Blocking in rabbit eyeblink conditioning is not due to learned inattention: Indirect support for an error correction mechanism of blocking

Blocking is a classical conditioning task in which prior training to one cue such as a tone reduces learning about a second cue such as a light, when subsequently trained as a tone-light compound. Blocking has been theorized to come about through a US-modulated error correction mechanism, by Rescorla &; Wagner (1972) as well as through a mechanism of learned inattention as theorized by Mackintosh (1973). In the case of eyeblink conditioning, an error correction mechanism has been hypothesized to take place in the cerebellum while some form of inattention has been hypothesized to take place in the hippocampal region. The hypothesis we., are testing is whether the mechanism of learned inattention is involved in blocking in rabbit eyeblink conditioning. If blocking in eyeblink conditioning is produced by a mechanism of learned inattention, then training to a previously blocked cue should be slower than training to that cue in a naïve animal. Rabbits that had received tone training followed by tone-light training exhibited blocking. Rabbits that had been previously blocked to the light acquired conditioned responses to the light at the same rate as naïve rabbits. This finding failed to support the hypothesis that blocking in rabbit eyeblink conditioning is due to learned inattention, but does support the Rescorla-Wagner mechanism of error correction. The present finding along with previous work on error correction mechanism in the cerebellar-brainstem circuit (Kim et al., 1998) lend support to the theory that blocking, at least in rabbit eyeblink conditioning, seems to be due to an error correction mechanism rather than a learned inattention mechanism.     

The decrement in conditioned fear with increased trials of simultaneous conditioning is not specific to the simultaneous procedure

Three experiments using a conditioned punishment paradigm with rat subjects examined the possibility that the nonmonotonic acquisition function previously found to characterize simultaneous conditioning was due to the noninformative nature of the conditioned stimulus (CS). In Experiment 1 the suppressive effects of a CS previously presented with an unconditioned stimulus (US) in a simultaneous and forward (informative) manner were compared following 20 and an additional 60 conditioning trials. Excitatory conditioning similarly diminished with increased trials for both the simultaneous and forward procedures. Experiment 2 employed a between-groups design. Simultaneous, forward, and trace conditioning procedures were compared following 20 or 100 trials. Each of the three 100-trial groups showed less resistance to extinction than their 20-trial counterparts. Experiment 3 determined that the decrement in excitatory conditioning for the 100-trial groups was not due to the greater number of US presentations, per se, but rather to the number of CS-US pairings. The nonmonotonic acquisition function observed with all three conditioning procedures indicated that informational factors were not responsible for the decrement observed in simultaneous conditioning. The pattern of results suggested that subjects receiving extended conditioning trials were better able to discriminate between training and testing.     

Implicit self-esteem is associated with higher levels of trait gratitude in women but not men

ABSTRACT

Higher levels of trait gratitude have been associated with measures of greater self-reported self-esteem. However, such self-report measures may be influenced by self-report biases. In this study we investigated for the first time whether implicit measures of self-esteem would be associated with greater trait gratitude in a sample of 88 undergraduate students (41 female). We observed that, in women (but not men), higher levels of trait gratitude were associated with higher implicit self-esteem (r = .26, p = .05), even when accounting for depressive symptoms. This finding may be of particular importance, as implicit measures of self-esteem have been more strongly associated with psychological health than explicit measures. Future research should further investigate whether the experience of gratitude affects self-esteem differently in men and women, as this knowledge may be important in informing the design of future gratitude interventions aimed at improving psychological health in men and women.     

Consolidation of vocabulary is associated with sleep in typically developing children,but not in children with dyslexia

Sleep is known to play an active role in consolidating new vocabulary in adults; however, the mechanisms by which sleep promotes vocabulary consolidation in childhood are less well understood. Furthermore, there has been no investigation into whether previously reported differences in sleep architecture might account for variability in vocabulary consolidation in children with dyslexia. Twenty‐three children with dyslexia and 29 age‐matched typically developing peers were exposed to 16 novel spoken words. Typically developing children showed overnight improvements in novel word recall; the size of the improvement correlated positively with slow wave activity, similar to previous findings with adults. Children with dyslexia showed poorer recall of the novel words overall, but nevertheless showed overnight improvements similar to age‐matched peers. However, comparisons with younger children matched on initial levels of novel word recall pointed to reduced consolidation in dyslexics after 1 week. Crucially, there were no significant correlations between overnight consolidation and sleep parameters in the dyslexic group. This suggests a reduced role of sleep in vocabulary consolidation in dyslexia, possibly as a consequence of lower levels of learning prior to sleep, and highlights how models of sleep‐associated memory consolidation can be usefully informed by data from typical and atypical development.     

Secondary psychopathy,but not primary psychopathy,is associated with risky decision-making in noninstitutionalized young adults

Although risky decision-making has been posited to contribute to the maladaptive behavior of individuals with psychopathic tendencies, the performance of psychopathic groups on a common task of risky decision-making, the Iowa Gambling Task (IGT; Bechara, Damasio, Damasio, & Anderson, 1994), has been equivocal. Different aspects of psychopathy (personality traits, antisocial deviance) and/or moderating variables may help to explain these inconsistent findings. In a sample of college students (N = 129, age 18–27), we examined the relationship between primary and secondary psychopathic features and IGT performance. A measure of impulsivity was included to investigate its potential as a moderator. In a joint model including main effects and interactions between primary psychopathy, secondary psychopathy and impulsivity, only secondary psychopathy was significantly related to risky IGT performance, and this effect was not moderated by the other variables. This finding supports the growing literature suggesting that secondary psychopathy is a better predictor of decision-making problems than the primary psychopathic personality traits of lack of empathy and remorselessness.