Electrical stimulation of the pedunculopontine tegmental nucleus in freely moving awake rats: time- and site-specific effects on two-way active avoidance conditioning

The pedunculopontine tegmental nucleus (PPTg) is involved in the regulation of thalamocortical transmission and of several functions related to ventral and dorsal striatal circuits. Stimulation of the PPTg in anesthetized animals increases cortical arousal, cortical acetylcholine release, bursting activity of mesopontine dopaminergic cells, and striatal dopamine release. It was hypothetized that PPTg stimulation could improve learning by enhancing cortical arousal and optimizing the activity of striatal circuits. We tested whether electrical stimulation (ES) of the PPTg, applied to freely-moving awake rats previously implanted with a chronic electrode, would improve the acquisition and/or the retention of two-way active avoidance conditioning, and whether this effect would depend on the specific PPTg region stimulated (anterior vs posterior) and on the time of ES: just before (pre-training) or after (post-training) each of three training sessions. The treatment consisted of 20 min of ES (0.2 ms pulses at 100 Hz; current intensity: 40-80 microA). The results showed that (1) this stimulation did not induce either any signs of distress nor abnormal behaviors, apart from some motor stereotyped behaviors that disappeared when current intensity was lowered; (2) pre-training ES applied to the anterior PPTg improved the acquisition of two-way active avoidance, (3) no learning improvement was found after either post-training ES of the anterior PPTg, or pre- and post-training ES of the posterior PPTg. The results give support to a role of PPTg in learning-related processes, and point to the existence of functional PPTg regions.     

Neuronal unit activity in the abducens nucleus during classical conditioning of the nictitating membrane response in the rabbit (Oryctolagus cuniculus).

Neuronal unit activity was recorded from the abducens (6th nerve) nucleus, the "final common path," during classical conditioning of the nictitating membrane (NM) response in the rabbit, with the use of a tone conditioned stimulus, an air puff unconditioned stimulus (UCS), 250-msec interstimulus interval, and 60-sec intertrial interval. Animals were given 2 days of conditioning training (104 trials in eight blocks per day) and 1 day of extinction. Control animals were given comparable periods of stimulus presentations, explicitly unpaired. Activity of small clusters of units--"multiple unit" recording--was compared with the amplitude-time course of the NM response. Between-blocks comparisons of neural and behavioral responses indicated an essentially perfect correlation during acquisition of the conditioned response (Day 1, r = .99; Day 2, r = .98) and a slightly lower correlation during extinction (r = .93) for the conditioning animals. Within-blocks comparisons indicated a close correspondence between the histograms of unit activity and the amplitude-time course of the NM response for the conditioning animals in all phase of training and for the control animals in the UCS trial blocks.     

组织中的高质量联结

组织中的高质量联结(HQC)指工作中短期的积极互动关系。它能使交往双方体验到活力、积极关照与相互交融, 并具有高情感承载力、关系张力与联结力三个特征。目前, HQC已成为积极组织行为学关注的热点问题之一, 它不仅对个体生理健康、工作态度、学习行为具有积极影响, 还能通过组织过程、高管团队的决策与张力、团队创新力作用于组织。而认知、情感和行为机制是构建与强化HQC的重要方法。未来HQC研究需要对其影响因素、构建与强化机制间关系做进一步讨论。     

An efficient one- and two-way avoidance apparatus capable of producing identical one- and two-way avoidance performance

A platformed one- and two-way avoidance apparatus is described in which the need for handling the subjects in the one-way task is eliminated and the two-way task is very quickly learned. The acquisition curves obtained for these two tasks are indistinguishable.     

Reevaluating evaluative conditioning: a nonassociative explanation of conditioning effects in the visual evaluative conditioning paradigm.

In 2 studies, the authors investigated whether evaluative conditioning (EC) is an associative phenomenon. Experiment 1 compared a standard EC paradigm with nonpaired and no-treatment control conditions. EC effects were obtained only when the conditioned stimulus (CS) and unconditioned stimulus (UCS) were rated as perceptually similar. However, similar EC effects were obtained in both control groups. An earlier failure to obtain EC effects was reanalyzed in Experiment 2. Conditioning-like effects were found when comparing a CS with the most perceptually similar UCSs used in the procedure but not when analyzing a CS rating with respect to the UCS with which it was paired during conditioning. The implications are that EC effects found in many studies are not due to associative learning and that the special characteristics of EC (conditioning without awareness and resistance to extinction) are probably nonassociative artifacts of the EC paradigm.     

Inhibitory conditioning in honeybees

Honeybees were rewarded with sucrose solution for choosing AX(a grey target, X, labelled with a distinctive stimulus, A) rather than ABX (a grey target labelled both with A and with another distinctive stimulus, B)-AX+/ABX- training. Tests of independent groups made after such training showed a clear preference not only for AX over ABX, but also for ABX over BX, and for X over BX. These experiments, along with some earlier ones to which they bring a new perspective, provide persuasive evidence, previously lacking, of inhibitory conditioning in honeybees.     

Sign-tracking in aversive conditioning

Two experiments were conducted to determine if rats tend to avoid contact with a stimulus that signals the occurrence of shock and contact a stimulus that signals the nonoccurrence of shock. The conditioned stimulus was a 60-sec platform presentation, and the unconditioned stimulus was a 2-sec inescapable shock. In each experiment, the emphasis was on two types of Pavlovian pairings: forward pairing in which each platform presentation was followed by shock, and backward pairing in which each platform presentation was preceded by shock and followed by a lengthy shock-free interval. Experiment 1 showed that in comparison with Random and CS-only procedures, the backward procedure produced a significant increase in approach and contact with the platform, but the forward procedure failed to produce a significant decrease in contact with the platform. Experiment 2, in which all groups were roughly equated for baseline levels of platform preference, demonstrated strong effects of both forward and backward conditioning. The experiments provide evidence for an aversive sign-tracking system in which animals' tendencies to withdraw from or approach and contact a platform CS are determined by the Pavlovian contingencies which render it a reliable signal for the occurrence or nonoccurrence of shock.     

Second-order conditioning in Drosophila

Associative conditioning in Drosophila melanogaster has been well documented for several decades. However, most studies report only simple associations of conditioned stimuli (CS, e.g., odor) with unconditioned stimuli (US, e.g., electric shock) to measure learning or establish memory. Here we describe a straightforward second-order conditioning (SOC) protocol that further demonstrates the flexibility of fly behavior. In SOC, a previously conditioned stimulus (CS1) is used as reinforcement for a second conditioned stimulus (CS2) in associative learning. This higher-order context presents an opportunity for reassessing the roles of known learning and memory genes and neuronal networks in a new behavioral paradigm.     

Effects of contextual conditioning and unconditional stimulus presentation on performance in appetitive conditioning

Four experiments with rat subjects examined the effects of contextual conditioning on conditioned appetitive performance. Experiment 1 compared the effects of contextual conditioning on performance to conditioned stimuli (CSs) with different conditioning histories. Contextual conditioning enhanced performance to the CS if the CS had first been conditioned and then extinguished, but had no effect on performance when the CS had been merely paired or unpaired with food. Experiments 2 and 3 then asked whether the effect on the extinguished CS was due to contextual conditioning acting as a cue for conditioning. In Experiment 2, extinction procedures in which extra unconditioned stimuli (USs) were presented during the intertrial intervals were found to reduce the CS's sensitivity to enhancement by contextual conditioning, but had no effect on spontaneous recovery. In Experiment 3, USs added to conditioning or extinction acquired the ability to cue the corresponding performance. Under some conditions, USs added to conditioning could suppress performance (Experiment 4). The results suggest that contextual conditioning has complex effects that can be better understood by recognizing that contextual conditioning, as well as the USs that create it,Mayacquire discriminative control over conditioned responding.     

Relative novelty of conditioning context influences directionality of glycemic conditioning

Previous experiments in which insulin was administered in a Pavlovian conditioning procedure obtained both hyperglycemic and hypoglycemic conditioned responses (CRs). In the present experiment the relationship of the conditioning context and the housing environment was varied. Two environments, wastebasket (WB) and metal cage (MC), were varied factorially as housing and conditioning contexts. Subgroups were injected with either insulin or saline for 6 days and then, on a test day for conditioning, all animals were administered saline. The results suggested that a hyperglycemic CR could be expected when the conditioning context is different from the housing context, but a hypoglycemic CR could be expected when the conditioning context and housing context are similar. The magnitude and reliability of conditioning were greater when it was conducted in the WB context than when conditioning was conducted in the MC context. These results are discussed in terms of stress arising from relative novelty of the conditioning environment and in terms of the salience of the conditioned stimulus (CS) used in glycemic conditioning studies.