A comparison of neuronal reactions during classical and instrumental conditioning under similar conditions

During the elaboration of an instrumental reflex, it is not obligatory to use a conditioned stimulus, which signals the necessity to generate an instrumental reaction in order to receive reinforcement. However, the presence of a conditioned stimulus simplifies analysis of instrumental reaction, which in this case is the response to the conditioned stimulus. On the other hand, it is necessary to distinguish between instrumental and classical conditioning, since in both cases the response to a conditioned stimulus increases. We studied neuronal analogs of classical and instrumental conditioning in the identified neurons responsible for the defensive closure of the pneumostome in the Helix mollusk under the same conditions. During classical conditioning, a mollusk received punishment after a tactile stimulus. During instrumental conditioning, a mollusk received punishment when an identified neuron did not generate an action potential in response to a tactile stimulus. The appearance of a painful stimulus did not depend on the generation or failure of a spike in the related control neuron. Another tactile stimulus, which was never paired with an unconditioned stimulus, was used as a discriminated stimulus. We also compared the behavior of such identified neurons during pseudoconditioning. The experiments were carried out in a semi-intact preparation. We examined how responses to the tactile and painful stimuli changed during different forms of training. It was shown that the dynamics of neuronal responses to a conditioned tactile stimulus were much more complex during instrumental conditioning and consisted of several phases. Throughout a learning session, neural system consecutively acquired information as to which kind of learning was presented, whether a reaction of the neural system must be generated or inhibited and which instrumental reaction is correct. We have demonstrated that response to a painful stimulus during classical conditioning decreases after short-term initial increase. However, during instrumental learning, the neurons controlling instrumental action remained highly sensitive to the unconditioned stimulus. Meanwhile, foreign neurons decreased their responses to the unconditioned stimulus. We may tentatively conclude that classical and instrumental paradigms are fundamentally different at the cellular level.     

Concomitant changes in classically conditioned heart rate and corneoretinal potential discrimination in the rabbit (Oryctolagus cuniculus)

Corneoretinal Potential (CRP) and heart rate changes were measured in a series of differential classical conditioning experiments in which the directionality of the heart rate response was related to (a) CRP acquisition, and (b) the certainty or uncertainty of the stimulus situation. The results suggested that heart rate decelerations were associated with stimuli that predict upcoming aversive events, while heart rate accelerations were associated with asymptotic CRP responding late in conditioning. These findings were interpreted in terms of (a) changes in general somatic activity, and (b) the cue properties associated with CSs which predict aversive events.     

Autonomic conditioning to monetary and social stimuli and aggression in children

Poor conditioning to punishment, such as loud tones or electric shock, has been proposed as an important factor involved in the etiology of aggressive and psychopathic behavior. However, it is not known whether the association holds when monetary or social stimulus is used as the unconditioned stimulus, and if aggressive individuals also have impaired conditioning to rewards. In this study, skin conductance responses in a conditioning task involving both monetary/social reward and punishment as unconditioned stimuli were assessed in 340 male and female 8‐ to 9‐year‐old children from the community. Children reported their reactive and proactive aggression using the Reactive and Proactive Aggression Questionnaire (RPQ; Raine et al., 2006). Results showed that monetary/social reward and punishment were effective in eliciting physiological classical conditioning in children, and that reduced reward conditioning was associated with high levels of proactive aggression in particular. Findings highlight the importance of distinguishing between reactive and proactive aggression when examining antisocial behavior in children, and suggest that reward‐oriented treatment programs may not be effective for children with more proactive, instrumental aggressive behavior.

     

奖惩对注意缺陷多动障碍儿童情感决策的影响

采用简化版儿童赌博任务,其中操纵了奖励和惩罚的强度,探察两种亚型（注意缺陷型和混合型）ADHD儿童的情感决策能力,同时采集儿童在任务中的皮肤电活动以探析ADHD儿童在情感决策中的生理机制。结果发现,在不同的奖惩强度下,ADHD儿童情感决策模式不同,在即刻奖励条件下,ADHD儿童情感决策的能力明显弱于正常对照组儿童,倾向于不利选择,所产生的预测性皮电振幅也明显低于正常对照组;在即刻惩罚条件下,ADHD儿童的情感决策能力未见异常。两种亚型ADHD儿童的表现模式相似。上述结果证明,ADHD儿童仅存在对奖励的异常敏感性,并确实影响了其决策能力,而其回避惩罚的能力正常。两种亚型ADHD儿童存在的问题相似     

Unconditional stimulus characteristics in rabbit eyelid conditioning.

Three experiments employed aversive or positive subcortical electrical stimulation in an unconditional stimulus (US) role in rabbit eyelid conditioning. Conditional response (CR) development to a tonal conditional stimulus (CS) was examined when the intracranial stimulation was combined with a conventional cheek-shock US (Experiment 1) or with a lightflash US (Experiment 2). Our findings were consistent with previus observations that the affective impact of the US is important in the development of an overt motor CR. The complex pattern of our results, however, implies that intracranial stimulation has multiple effects on conditioning and argues against any unidimensional interpretation of these outcomes. Our analysis of CR-contingent intracranial stimulation presentation in Experiment 3 indicated that such stimulation does not act as a Thorndikian reward or punishment in rabbit eyelid conditioning.     

Negative reinforcement as shock-frequency reduction

Is a conditioned aversive stimulus necessary in avoidance conditioning? Or is a reduction in the rate of aversive stimulation alone sufficient to generate and maintain an avoidance response? Rats were subjected to an avoidance procedure in which shocks occurred randomly in time, but a response could reduce the overall rate of shock. Fifteen acquisition curves, obtained from 16 animals, showed both immediate and delayed, rapid and gradual increases in response rate; there was no representative acquisition curve. Response rates were directly related to the amount by which the response reduced shock frequency. In extinction, when shock rates were not affected by responding, the response total was inversely related to the amount by which the response had reduced shock frequency during prior conditioning, with as many as 20,000 extinction responses when the shock frequency reduction had been relatively small. Responding on this procedure shows that avoidance conditioning can occur without benefit of either classical exteroceptive stimuli or covert stimuli inferred from the temporal constancies of a procedure. It also shows that reduction in shock rate is alone sufficient to maintain avoidance.     

Expectancy-learning and evaluative learning in human classical conditioning: affective priming as an indirect and unobtrusive measure of conditioned stimulus valence

It has been argued that in classical conditioning two processes might be operative. First, one may learn that the conditioned stimulus (CS+) is a valid predictor for the occurrence of the biologically negative or positive event (US; expectancy-learning). Second, one may learn to perceive the conditioned stimulus itself as a negative or positive stimulus, depending on the valence of the event it has been associated with (evaluative learning). Until the present, however, both forms of learning have been investigated using rather different conditioning procedures. Using a differential aversive conditioning preparation with pictures of human faces as CSs and an electrocutaneous stimulus as US, we were able to demonstrate that both forms of learning can co-occur. Moreover, the extent of evaluative learning in this aversive conditioning procedure did not significantly differ from the amount of evaluative learning in an evaluative conditioning procedure with positive and negative adjectives as USs, which was administered to the same participants. In the present study evaluative learning was not only indexed by direct evaluative ratings, but we introduced affective priming as an indirect and unobtrusive, reaction time based measure of stimulus valence. Finally, imagery instructions during acquisition did not facilitate expectancy-learning nor evaluative learning.     

Differentiation between vicarious instigation and classical conditioning of electrodermal responses

In past research of vicarious conditioning when a conditioned stimulus (CS) was repeatedly presented both to a model and an observer, the observer's reaction to the CS may have been the result of a vicariously conditioned reaction to the CS, as well as a vicariously instigated reaction to the inferred emotional state of the model who anticipates the reception of a noxious stimulus when the CS is presented. In order to partial out these two reactions, the present experiment employed 32 subjects of both sexes who took part in a two-group study of differential, vicarious classical conditioning of skin conductance responses. In one of the group, the tones serving as CS+ and CS- and which preceded the aversive and non aversive events to the mode, were presented over earphones to both the confederate model and the observer subject. In the second group, only the subjects had earphones on and were led to believe that the model was not aware of the CS presentations. This eliminated the possibility of vicariously instigated reactions. Although the conditioning effects produced in the present study were somewhat weak, results clearly showed equal levels of vicarious instigation and conditioning in the two groups. These results indicate that the potential confounding of these two reactions studies has not significantly affected result or conclusions from previous studies.     

Conditioned response-contingent delays of the unconditioned stimulus in human aversive conditioning.

Four groups of subjects were given either 0. 100, 500, or 1,000 msec delays of the unconditioned stimulus (UCS) contingent upon the occurrence of a conditioned response (CR) and were given a UCS 515 msec after conditioned stimulus (CS) onset when a CR did not occur. A fifth group received standard classical conditioning trials with an interstimulus interval of 515 msec. Overall performance decreased as CR-contingent UCS delay increased, with the classical conditioning group approximating the performance of the group receiving the 100-msec delay. The data were analyzed with the two-phase model of conditioning and the following results were obtained: The duration of Phase 1 of the model increased with contingent delay; operator limits associated with CR trials or with combined CR-CR (CR absent) trials decreased as a function of delay; and operator limits associated exclusively with CR trials were unaffected by the delay. Subjects receiving a contingent delay of 0 msec gave the shortest latency responses and exhibited reliable latency decreases across trials, suggesting an attempt to "beat" the UCS. The results were interpreted as contrary to what would be expected from low-of-effect theories which postulate that reinforcement results from a CR-UCS interaction, although they could be subsumed under a drive or an associative strength theory in which the aversive, or CR-supportive, strength of the UCS is assumed to be negatively correlated with contingent UCS delay.     

An automated positive reward method for measuring acoustic sensitivity in fish

A microcomputer-controlled positive reward operant conditioning paradigm was developed to measure auditory sensitivity of the goldfish (Carassius auratus). Although other procedures have been used to measure hearing sensitivity in fish, all earlier studies have been done with some form of aversive conditioning. Goldfish were trained with a positive reinforcement method to determine hearing thresholds at 200, 500, 1000, 1500, and 2000 Hz. The audiogram obtained in this study is in close agreement with thresholds obtained with instrumental avoidance and classical conditioning procedures involving negative reinforcement (shock). The similarity in threshold data validates the effectiveness of the positive reinforcement paradigm described here. The major advantages of the present paradigm are the following: (1) No physical punishment such as electric shock is used, and (2) the versatility of the system allows easy modification for a variety of experiments.     

Salivary conditioning with antennal gustatory unconditioned stimulus in an insect

Classical conditioning of olfactory conditioning stimulus (CS) with gustatory unconditioned stimulus (US) in insects has been used as a pertinent model for elucidation of neural mechanisms underlying learning and memory. However, a conditioning system in which stable intracellular recordings from brain neurons are feasibly obtained while monitoring the conditioning effect has remained to be established. Recently, we found classical conditioning of salivation in cockroaches Periplaneta americana, in which an odor was associated with sucrose solution applied to the mouth, and this conditioning could be monitored by activities of salivary neurons. Application of gustatory US to the mouth, however, leads to feeding movement accompanying a movement of the brain that prevents stable recordings from brain neurons. Here we investigated whether a gustatory stimulus presented to an antenna could serve as an effective US for producing salivary conditioning. Presentation of sucrose or sodium chloride solution to an antenna induced salivation and also increased activities of salivary neurons. A single pairing trial of an odor with antennal presentation of sucrose or sodium chloride solution produced conditioning of salivation or of activities of salivary neurons. Five pairing trials led to a conditioning effect that lasted for one day. Water or tactile stimulus presented to an antenna was not effective for producing conditioning. The results demonstrate that gustatory US presented to an antenna is as effective as that presented to the mouth for producing salivary conditioning. This conditioning system provides a useful model for studying the neural basis of learning at the level of singly identifiable neurons.     

Risk Taking and Sensitivity to Punishment in Children with ADHD,ODD, ADHD+ODD,and Controls

We used the Balloon Analog Risk Task (BART) to examine risk taking and sensitivity to punishment, two relevant aspects of behavioral inhibition, in 203 school-age children with attention-deficit/hyperactivity disorder (ADHD), oppositional defiant disorder (ODD), ADHD+ODD, and controls. Participants earned points on the BART by pumping 30 separate balloons that exploded at variable intervals. No points were earned on a trial when a balloon exploded. The number of pumps across all balloons estimated risk taking and the reduction in pumps following balloon explosions was interpreted as an indicator of sensitivity to negative punishment. We found that all groups significantly differed from one another on risk taking. The ADHD+ODD group pumped the most, followed by the ODD, ADHD, and the control group, respectively. For sensitivity to negative punishment, all groups performed differently, with the ODD group showing the least sensitivity to an exploded balloon, followed by the ADHD, control, and ADHD+ODD groups, respectively. Children with ADHD+ODD demonstrated significantly different patterns of risk taking and sensitivity to negative punishment than children with either ADHD-only or ODD-only. ADHD youth with comorbid ODD had the greatest levels of risk taking, but they were also the most sensitive to negative punishment. The relationship between ADHD and ODD, as well as the nature of comorbidity in constructs related to risk taking and related behaviors, are discussed.     

Effect of unconditioned stimulus magnitude on the emergence of conditioned responding

Although unconditioned stimulus (US) magnitude influences conditioning, no experiment has addressed whether it influences a decision point at which the organism first responds (Gallistel & Gibbon, 2000). Two appetitive conditioning experiments with rats confirmed that the rate of food cup entries and proportion of head jerking were related to the number of pellets (US) provided after the conditioned stimulus. In addition, the onset of responding measured by the number of reinforcers to a criterion or by a quantitatively identified change point also reflected US magnitude. Two aversive conditioning experiments also found that the amount and onset of freezing were related to footshock intensity. All experiments identified a trial at which responding increased abruptly in individual subjects. However, the point where the increase occurred was earlier with larger USs.     

Asymmetrical effects of Pavlovian excitatory and inhibitory aversive transfer on Pavlovian appetitive responding and acquisition

Predictions of a theory of Pavlovian motivational transfer, which incorporates principles of both the theory of reciprocal inhibition and the Rescorla-Wagner model, were tested in several Pavlovian aversive to Pavlovian appetitive transfer tasks. As predicted, the presence of a signal for an aversive event, conditioned stimulus (AV CS+), reliably suppressed performance of appetitive conditioned responses (CRs) whether imposed during acquisition or on independently established responding. Acquisition of appetitive responding to a novel CS reinforced in compound with an AV CS+, however, was enhanced (“superconditioning”). This observation suggests that the effects of a discrepancy between expectation and actual outcome on a conditioning trial are influenced by the affective value of both the expectation and the reinforcer. These transfer effects were not symmetrical for an inhibitory aversive stimulus (AV CS?). An AV CS? did not enhance appetitive responding compared to a random control condition, nor did the AV CS? reduce (i.e., block) appetitive conditioning to a novel CS when appetitive reinforcement occurred in the presence of the AV CS?. Comparison of the two shock-exposed conditions with a naive control condition suggests that previous results that were apparently consistent with inhibitory aversive enhancement and blocking of appetitive conditioning may have been due to aversive context conditioning.     

Transfer of conditioned appetitive stimuli to conditioned aversive excitatory and inhibitory stimuli

The transfer of Pavlovian appetitive stimuli to Pavlovian aversive stimuli was examined in three experiments. In Experiment 1, rats received appetitive (Ap) conditioning designed to establish a flashing-light stimulus as either a CS+, CSo, or CS? for food, or to maintain it as a novel stimulus for US-alone subjects. Then, the stimulus was employed as a signal for weak shock in conditioned-emotional-response (CER) training. Both acquisition and extinction results showed that the ApCS+ facilitated and the ApCS? retarded aversive excitatory conditioning relative to the ApCSo and US-alone controls. Experiment 2 replicated the findings of Experiment 1 with both a moderate and a severe shock in CER training. In Experiment 3, different groups received the same appetitive conditioning as before, but to a flashing-light stimulus which was then employed as a signal for no shock in CER training. The ApCS? facilitated and the ApCS+ retarded aversive inhibitory conditioning relative to ApCSo and US-alone controls. Collectively, these findings establish that, in Pavlovian conditioning, transfer of an appetitive CS to an aversive excitor or inhibitor is facilitated by maintaining the initial conditioning contingency.     

Children’s Reward and Punishment Sensitivity Moderates the Association of Negative and Positive Parenting Behaviors in Child ADHD Symptoms

Atypical reward processing, including abnormal reward responsivity and sensitivity to punishment, has long been implicated in the etiology of ADHD. However, little is known about how these facets of behavior interact with positive (e.g., warmth, praise) and negative (e.g., hostility, harsh discipline) parenting behavior in the early expression of ADHD symptoms in young children. Understanding the interplay between children’s reward processing and parenting may be crucial for identifying specific treatment targets in psychosocial interventions for ADHD, especially given that not all children benefit from contingency-based treatments (e.g., parent management training). The study consisted of a sample of kindergarten children (N?=?201, 55% male) and their parents, who completed questionnaires about their parenting practices, their child’s behaviors and participated in an observed parent-child play task in the laboratory. Children’s reward responsivity and sensitivity to punishment were positively associated with child ADHD symptoms. However, children with high reward responsivity had more symptoms of ADHD but only under conditions of low negative parenting (self-reported and observed) and high self-reported positive parenting, compared to children with low reward responsivity. Children with high sensitivity to punishment had more ADHD symptoms relative to children with low sensitivity to punishment, but only under conditions in which observed praise was infrequent. Results provide evidence that individual differences in sensitivity to reward/punishment may be an important of marker of risk for ADHD, but also highlights how children’s responses to positive and negative parenting behavior may vary by children’s sensitivities. Clinical and treatment implications are discussed.     

Analysis of treatments to alleviate forgetting in rats

Two experiments with rats investigated the effectiveness of prior-cuing treatments for alleviating forgetting of aversive conditioning. The aim was to see which retrieval cues would be most effective within different contexts. Experiment 1 examined the contexts of classical fear conditioning and instrumental avoidance training. The results indicated that the response components were sufficient to reinstate avoidance training, whereas the unconditioned stimulus (US) was most effective for classical fear conditioning. In Experiment 1, the reinforcer per se was ineffective in reinstating instrumental avoidance training. Experiment 2 manipulated the training context and found that the US could be made an effective prior-cuing treatment for instrumental training if classical conditioning components were more prevalent during training. These results are interpreted to mean that a "critical context" must be reinstated by the cuing treatment if this treatment is to promote retrieval of the memory.     

Underlying processes in the poor response inhibition of children with Attention-Deficit/Hyperactivity Disorder

This study evaluated the effects of reward, punishment, and reward + punishment on the impulsive responses of ADHD children. The impulsive responses of ADHD and normal control boys (30 per group) were compared during performance of a go/no-go task, administered under reward-only, punishment-only, and reward + punishment conditions. When differences in aggression, anxiety, and IQ between these groups were controlled for, results indicated that the impulsivity levels of the ADHD group were higher than the control group in all three reinforcement conditions. Also, the ADHD group was more impulsive in the reward + punishment condition, compared to the reward-only and punishment-only conditions, and there was no difference between the reward-only and punishment-only conditions. The control groups showed no difference across the three reinforcement conditions. These findings raise the possibility that the poor response inhibition of ADHD children may be related to both a generalized inhibitory deficit and a response modulation deficit.     

Aversive conditioning under conditions of restricted awareness: Effects on spatial cueing

In the literature on aversive conditioning there is still debate on the role of awareness. According to some authors, affective learning can occur with or without contingency learning (dual-process model), whereas others argue that a single process produces both affective responses and contingency knowledge. Although many studies have investigated these models, the results to date are inconclusive. Based on a review of the literature, a new series of experiments was designed to examine aversive conditioning in the absence of contingency awareness. In the present study we examined the effects of subliminal aversive conditioning on a spatial cueing task. Awareness was stringently tested after conditioning. Three kinds of awareness were distinguished: contingency awareness (awareness of the CS?US contingencies, where CS is the conditioned stimulus, and US is the unconditioned stimulus), perceptual awareness (awareness of the perceptual differences between the CSs), and US expectancy (awareness of a threat feeling when confronted with the CS+, but not when confronted with the CS?). The results of three experiments demonstrated that responses on the spatial cueing task were modulated by subliminal aversive conditioning. Importantly, none of the participants was contingency aware or able to perceptually discriminate between the conditioned stimuli. However, in Experiment 3, only those participants showing some level of postconditioning expectancy awareness exhibited conditioning effects. These experiments suggest that subliminal aversive conditioning produces small but significant effects, which may be modulated by expectancy awareness.