On neurotransmitter mechanisms of reinforcement and internal inhibition

Experiments reported in this study have been performed in order to investigate cholinergic and GABA-ergic neurotransmitter systems and substance P in the realization of internal inhibition and pain reinforcement. This was accomplished during the elaboration of inhibitory and defensive conditioned reflexes to light flashes in alert, nonimmobilized rabbits. Present results together with a review of past research indicate that the cholinergic system is directly involved in transmitting the effects of pain reinforcement to neocortical neurons. Substance P, a neuropeptide, reduces the background activity of neocortical and hippocampol neurons and the response of cortical neurons to pain and positive conditioned stimuli. The cholinergic system and substance P exert a modulating effect on the elaboration of internal inhibition. Phenybut, a GABA derivative capable of penetrating the blood-brain barrier, enhances inhibitory hyperpolarization in the cerebral cortex and improves discrimination between the inhibitory and reinforcing light flashes. It appears, therefore, that the GABA-ergic system plays a leading part in the elaboration of internal inhibition. Neuronal activity and slow potential changes in response to positive conditioned and pain stimuli occur in the same direction after administering the preparations, and the dynamics of these changes is different from that in responses to inhibitory stimuli. It may be supposed on these grounds that the neurotransmitter and neuromodulator systems studied possess a considerable degree of plasticity.     

Forebrain mechanisms related to internal inhibition and sleep

In experiments performed on cats and monkeys over the past nine years a “forebrain inhibitory system” has been investigated through recording of neurophysiologic, behavioral, reflexive and intracellular parameters. This forebrain system is capable of expressing its inhibitory influences widely throughout the body, and on both somatic and visceral mechanisms. Electrical stimulation within this system has been shown to: a) suppress ongoing behavior, synchronize the EEG and induce the initial stages of sleep. These behavioral effects could be conditioned to indifferent stimuli. Other studies have shown that lesions within this system result in marked alterations in sleep patterns and in behavioral hyperactivity,b) Inhibit remarkably monosynaptic and polysynaptic reflexes in the brain stem and at cervical and lumbosacral levels of the spinal cord.c) Induce hyperpolarizing potentials within motoneurons of the final common path. Cl infusion caused the hyperpolarization to change to depolarization. Studies of the “forebrain inhibitory system” indicate that at least in part it is a descending system involving both multisynaptic (loop) pathways and direct pathways. It is felt that descending circuits from the forebrain to inhibitory centers in the medulla are responsible for the effects observed at the final common paths from stimulation in the forebrain. It has been found that behaviorally, reflexively and intracellularly, the “forebrain inhibitory system” acts generally in opposition to the reticular activating system of the brain stem, and that the achievement of an organism’s overt behavioral patterns depends on the functional state of both systems.     

弗洛伊德心理学的神经生理学模式

将研究人类大脑的神经科学与研究人类心智的精神分析相结合的设想,源于精神分析心理学的创始人弗洛伊德,精神分析理论中一直隐含和贯穿着一种神经学或神经生理学的模式.弗洛伊德提出的这个神经学模式包括神经元和能量或数量两个元素,其工作原理是神经元的惯性原理.     

信任的心理和神经生理机制

信任是建立在对他人的意向或行为的积极预期基础上而敢于托付（愿意承受风险）的一种心理状态。心理学家以及组织管理学家通过对信任发展的研究提出了信任发展的二元互动模型、理性选择模型、动机归因模型和可信赖程度--合作双螺旋模型。背叛行为会对信任关系的建立与发展带来永久性的伤害。已有的关于信任的神经生理机制的研究表明：人们所表现出的信任行为与其催产素水平密切相关,而且信任与背纹状体、前脑岛以及处理奖赏信息相关的脑区--伏隔核、尾状核、腹内侧额叶/前额脑区底部和侧前扣带皮层--的活动相关联。尽管目前关于信任的研究已经取得了很大进展,但是要解开信任的心理机制及其神经生理机制之谜,还需要进一步的研究。     

Neurophysiologic findings in chronic alcohol abuse

Neurophysiological examinations of 100 long term alcohol dependent patients who were having neuropsychiatric treatment, showed symptoms of polytopic damage of the peripheral and central nervous system. The results show that for recognition of the damage an extensive diagnostic programme must be used.     

多源评价的特点与内在机制

多源评价在国外企业中的运用已日益成熟, 但在我国还停留在探索与发展阶段。基于已有的研究发现, 围绕评价过程、评价源及被评价者三方面对多源评价的特点及内在机制进行了探讨与分析。从评价过程看, 其评价目的具有多重性, 评价形式注重匿名性, 且评价结果的合理应用非常重要; 从评价源看, 不同评价源间的评价一致性较低, 且易造成晕轮效应和宽大效应; 从被评价者来看, 个体对多源评价结果的反应, 受到个性特征、反馈信号及自我-他人评价间差距等因素影响。研究也发现, 多源评价所带来的绩效改进结果具有不稳定性。基于此, 如何提高多源评价过程的有效性与准确性, 改善评价者对评价结果的反应, 以及如何对多源评价结果进行有效汇总等是未来值得研究的重要内容。     

The neurophysiological validation of the hyperpolarization theory of internal inhibition

The experiments in conscious non-immobilized rabbits showed that cessation of the reactions without reinforcement (elaboration of the internal inhibition) is accompanied by an enhanced phasic state, by alternation of activation and inhibition of neuron firing, and by the corresponding slow potential oscillation (SPO). These changes can be either localized, predominantly in the structures of conditioned stimulus, or, under enhancement of the inhibitory state, generalized in the brain structures. On the basis of our experience and published data, it is concluded that the above event results from relative enhancement of the inhibitory hyperpolarizing processes due to increase in reactivity of the inhibitory systems to stimulus, which acquires inhibitory properties during learning. Changes in the excitability and reactivity of neuron populations appearing during enhancement of the hyperpolarizing inhibition, and differing in the various brain structures, play an active role in the execution of the main function of the internal inhibition: limitation of excitation transmission to the effectors. An inhibitory mediator gamma aminobutyric acid (GABA) is of great importance in inhibiting the excitation in response to the stimulus which lost its biological significance. These experimental data and their interpretation in the light of published data give the basis for the development of the hyperpolarization theory of internal inhibition.     

视觉搜索中注意模板促进搜索的内在机制

生物的视觉搜索能力对适应外部复杂环境具有非常重要的生存意义。注意模板可以在搜索任务的过程中增强相关信息和抑制无关信息,从而快速找到目标。总结近期研究结果主要有以下发现：在建立注意模板的过程中并不能明确是基于语义信息还是视觉特征信息;注意模板不仅可以存储在工作记忆中,也可以存储在长时记忆中;不同类型注意模板的神经机制存在差异。未来的研究应关注注意模板在建立过程中内部信息如何传递,并关注不同人群注意模板的神经机制,以及解决拒绝模板抑制机制的理论争议。     

Changing internal constraints on action: the role of backward inhibition

Flexible control of action requires the ability to disengage from previous goals or task sets. The authors tested the hypothesis that disengagement during intentional shifts between task sets is accompanied by inhibition of the previous task set ("backward inhibition"). As an expression of backward inhibition the authors predicted increased response times when shifting to a task set that had to be abandoned recently and, thus, suffers residual inhibition. The critical backward inhibition effect on the level of abstractly defined perceptual task sets was obtained across 6 different experiments. In addition, it was shown that backward inhibition can be differentiated from negative priming (Experiment 2), that it is tied to top-down sequential control (Experiment 3), that it can account at least partially for "residual shift costs" in set-shifting experiments (Experiment 4), and that it occurs even in the context of preplanned sequences of task sets (Experiment 5).     

饮酒对反应抑制的影响及其神经机制

反应抑制是指个体抑制不合适、不安全、或不需要的行为的能力,是重要的执行控制功能,在成瘾行为的作用下易受到损害。目前众多研究发现饮酒行为与个体反应抑制功能的表现关系密切,即便在个体戒断后也有长时间影响,且对饮酒者后代的抑制能力形成破坏,提高了后代出现成瘾行为的风险。随后从脑结构和神经递质两方面探讨饮酒影响反应抑制功能的机制,并整理了近些年基于双重加工模型提出的反应抑制训练及其在临床干预饮酒行为上的作用。未来研究仍有不少问题值得探索,同时考虑遗传和环境因素是相关研究的关键。     

Contextual control of inhibition with reinforcement: adaptation and timing mechanisms

Four experiments with rats studied the effects of switching the context after Pavlovian conditioning. In three conditioned suppression experiments, a large number of conditioning trials created "inhibition with reinforcement" (IWR), in which fear of the conditional stimulus (CS) reached a maximum and then declined despite continued CS-unconditional stimulus pairings. When IWR occurred, a context switch augmented fear of the CS; IWR and augmentation were highly correlated. Neither IWR nor augmentation resulted from inhibition of delay (IOD): In conditioned suppression, IWR and augmentation occurred without IOD (Experiment 3), and in appetitive conditioning (Experiment 4), IOD occurred without IWR or augmentation. IWR may occur in conditioned suppression because the animal adapts to fear of the CS in a context-specific manner. The authors discuss several implications.     

Effect of spatial inhibition on saccade trajectory depends on location-based mechanisms

Abstract:  Saccade trajectory often curves away from a previously attended, inhibited location. A recent study of curved saccades showed that an inhibitory effect prevents ineffective reexamination during serial visual search. The time course of this effect differs from that of a similar inhibitory effect, known as inhibition of return (IOR). In the present study, we examined whether this saccade-related inhibitory effect can operate in an object-based manner (similar to IOR). Using a spatial cueing paradigm, we demonstrated that if a cue is presented on a placeholder that is then shifted from its original location, the saccade trajectory curves away from the original (cued) location (Experiment 1), yet the IOR effect is observed on the cued placeholder (Experiment 2). The inhibitory mechanism that causes curved saccades appears to operate in a location-based manner, whereas the mechanism underlying IOR appears to operate in an object-based manner. We propose that these inhibitory mechanisms work in a complementary fashion to guide eye movements efficiently under conditions of a dynamic visual environment.     

The role of internal inhibition and the frontal lobes in child development

The theory that children show a predominance of excitation over internal inhibition and that this is due to inadequate development of the frontal lobes is explored and extended. Experimental results show that children resemble leucotomised monkeys in their difficulty in overcoming an initial preference in discrimination tasks.     

Scene-based and object-centered inhibition of return: evidence for dual orienting mechanisms

We investigated whether inhibition of return (IOR) could be observed in location-based, scene-based, and object-centered frames of reference. IOR was found to move both with a separate cued object (scene-based) and with a location within a single rotating object (object-centered). Importantly, however, IOR was also associated with the environmental location cued when cuing was of a separate object (scene-based), whereas facilitation of the cued location was found when cuing was of a component within an object. These results suggest that location is of central importance to scene-based representations of separate objects, which appear to be encoded in viewer-centered coordinates, whereas environmental locus is of little relevance when attention orients within a single object. The results also provide further evidence for the coexistence of both excitation and inhibition associated with uninformative exogenous cues.     

Generalization as a behavioral window to the neural mechanisms of learning internal models

In generating motor commands, the brain seems to rely on internal models that predict physical dynamics of the limb and the external world. How does the brain compute an internal model? Which neural structures are involved? We consider a task where a force field is applied to the hand, altering the physical dynamics of reaching. Behavioral measures suggest that as the brain adapts to the field, it maps desired sensory states of the arm into estimates of force. If this neural computation is performed via a population code, i.e., via a set of bases, then activity fields of the bases dictate a generalization function that uses errors experienced in a given state to influence performance in any other state. The patterns of generalization suggest that the bases have activity fields that are directionally tuned, but directional tuning may be bimodal. Limb positions as well as contextual cues multiplicatively modulate the gain of tuning. These properties are consistent with the activity fields of cells in the motor cortex and the cerebellum. We suggest that activity fields of cells in these motor regions dictate the way we represent internal models of limb dynamics.     

Neurophysiologic evaluation of early cognitive development in high-risk infants and toddlers

New knowledge of the perceptual, discriminative, and memory capabilities of very young infants has opened the door to further evaluation of these abilities in infants who have risk factors for cognitive impairments. A neurophysiologic technique that has been very useful in this regard is the recording of event-related potentials (ERPs). The event-related potential (ERP) technique is widely used by cognitive neuroscientists to study cognitive abilities such as discrimination, attention, and memory. This method has many attractive attributes for use in infants and children as it is relatively inexpensive, does not require sedation, has excellent temporal resolution, and can be used to evaluate early cognitive development in preverbal infants with limited behavioral repertories. In healthy infants and children, ERPs have been used to gain a further understanding of early cognitive development and the effect of experience on brain function. Recently, ERPs have been used to elucidate atypical memory development in infants of diabetic mothers, difficulties with perception and discrimination of speech sounds in infants at risk for dyslexia, and multiple areas of cognitive differences in extremely premature infants. Atypical findings seen in high-risk infants have correlated with later cognitive outcomes, but the sensitivity and specificity of the technique has not been studied, and thus evaluation of individual infants is not possible at this time. With further research, this technique may be very useful in identifying children with cognitive deficits during infancy. Because even young infants can be examined with ERPs, this technique is likely to be helpful in the development of focused early intervention programs used to improve cognitive function in high-risk infants and toddlers.     

Developmental emergence of self-referential and inhibition mechanisms of body movements underling felicitous behaviors

In young infants, activation or inhibition of body movements on perception of environmental events is important to enable them to act on the world or understand the world. To reveal the development of this ability, we observed movement patterns in all four limbs under the two experimental conditions. Infants assigned to the interaction condition were provided a connection between their arm and a toy, which allowed movements of the critical arm to produce movements in the overhead mobile. Infants assigned to the stimulation condition were presented with similar movements of the toy emulated by the experimenter. In 3-month-old infants, the arm movements increased under the interaction condition, whereas they decreased under the stimulation condition. Such condition-dependent behavior dissociation was not observed in 2-month-old infants. These results suggest that the distinct behavior of an "observer" of environmental events was differentiated from that of a "player" interacting with the surroundings between 2 and 3 months of age. The emergence of differentiation of behaviors points toward the development of self-referential and inhibition mechanisms in the perceptual-motor and attention/evaluation system in the cortico-subcortical network.