工作记忆与情景记忆的相互作用

虽然Baddeley的工作记忆模型得到大量实验研究的支持,但是有关工作记忆和长时记忆之间的关系未能得到详细阐述。来自神经心理学的证据表明,工作记忆与情景长时记忆任务均诱发了前额区的激活,但同时发现前额区存在不同的功能分区,可能在工作记忆与情景记忆过程中具有独立的执行功能。工作记忆与情景记忆的相互作用是当前记忆研究关注的问题。已有研究发现,在情景记忆对工作记忆的作用过程中,时间进程与头皮分布均显示了年龄效应与材料加工特点。而工作记忆对情景记忆的作用中,则发现工作记忆早期加工可能对情景记忆的成功形成有更大促进作用。今后的研究应在理论模型支持下,利用多种技术手段探讨两种记忆相互作用的神经加工机制     

The role of visual experience on the representation and updating of novel haptic scenes

We investigated the role of visual experience on the spatial representation and updating of haptic scenes by comparing recognition performance across sighted, congenitally and late blind participants. We first established that spatial updating occurs in sighted individuals to haptic scenes of novel objects. All participants were required to recognise a previously learned haptic scene of novel objects presented across the same or different orientation as learning whilst they either remained in the same position to moved to a new position relative to the scene. Scene rotation incurred a cost in recognition performance in all groups. However, overall haptic scene recognition performance was worse in the congenitally blind group. Moreover, unlike the late blind or sighted groups, the congenitally blind group were unable to compensate for the cost in scene rotation with observer motion. Our results suggest that vision plays an important role in representing and updating spatial information encoded through touch and have important implications for the role of vision in the development of neuronal areas involved in spatial cognition.     

Top-down predictions in the cognitive brain

The human brain is not a passive organ simply waiting to be activated by external stimuli. Instead, we propose that the brain continuously employs memory of past experiences to interpret sensory information and predict the immediately relevant future. The basic elements of this proposal include analogical mapping, associative representations and the generation of predictions. This review concentrates on visual recognition as the model system for developing and testing ideas about the role and mechanisms of top-down predictions in the brain. We cover relevant behavioral, computational and neural aspects, explore links to emotion and action preparation, and consider clinical implications for schizophrenia and dyslexia. We then discuss the extension of the general principles of this proposal to other cognitive domains.     

急性生理应激对大鼠的行为及脑神经颗粒素磷酸化水平的影响

突触特异性蛋白质在应激所致行为效应的中枢机制中的可能角色日益受到关注。神经颗粒素（Neurogranin,NG）是一种新发现的突触特异性蛋白质,主要分布在前额叶、杏仁核和海马区域,参与突触结构和功能可塑性机制,可能涉及到应激所致行为效应中枢机制。但是,关于NG、应激和行为之间的关系国内外尚缺乏系统的研究报道。本研究主要是探讨急性生理应激对大鼠行为和NG的作用,以及NG的变化与应激性行为效应之间的相互关系。以急性强迫性冷水游泳应激,建立生理应激动物模型。将40只雄性SD大鼠随机分为游泳应激组1（SS1,接受游泳应激和行为测试）、游泳应激组2（SS2,接受游泳应激而不接受行为测试）、正常对照组1（C1,接受行为测试）和正常对照组（C2,不给予任何处理）（n=10）。以旷场行为和高架十字迷宫任务来评定大鼠应激后的行为变化,Western blotting方法测定海马和前脑皮层中的NG含量和磷酸化水平。结果表明：应激后SS1组的呆滞行为增加,与C1组比较,差异有显著性, P<0.01; SS1组海马的NG含量和NG磷酸化水平增高,与C1和C2组相比,差异有显著性,均为P<0.05; SS1组皮层的NG含量增高,与C1和C2组相比,差异有显著性,均为P<0.01;SS1组皮层的NG磷酸化水平增高,与C1组相比,差异具有显著性,P<0.01;前脑皮层的NG磷酸化水平与呆滞行为之间的相关达显著水平。提示该应激源能诱发动物明显的恐惧反应,呆滞行为是反映急性生理应激导致行为障碍的敏感的行为学指标,海马和前脑皮层均是对急性生理应激反应敏感的脑区。NG的磷酸化水平可能是反映急性生理应激所致行为障碍的一项新的生物学指标     

前额叶在双语词汇通达中的抑制作用——对一例前额叶损伤双语病人的研究

先前研究表明,双语词汇产生和双语词汇理解过程中存在着抑制机制。本实验以一例前额叶损伤中-英双语病人为研究对象,通过让其完成系统的语言测试任务和认知实验任务,考察了双语词汇通达过程中抑制机制的神经基础。总的实验结果初步表明,前额叶在双语词汇通达过程中发挥着重要的抑制作用。     

Differential involvement of left prefrontal cortex in inductive and deductive reasoning

While inductive and deductive reasoning are considered distinct logical and psychological processes, little is known about their respective neural basis. To address this issue we scanned 16 subjects with fMRI, using an event-related design, while they engaged in inductive and deductive reasoning tasks. Both types of reasoning were characterized by activation of left lateral prefrontal and bilateral dorsal frontal, parietal, and occipital cortices. Neural responses unique to each type of reasoning determined from the Reasoning Type (deduction and induction) by Task (reasoning and baseline) interaction indicated greater involvement of left inferior frontal gyrus (BA 44) in deduction than induction, while left dorsolateral (BA 8/9) prefrontal gyrus showed greater activity during induction than deduction. This pattern suggests a dissociation within prefrontal cortex for deductive and inductive reasoning.     

Magnetic stimulation studies of foveal representation

The right and left visual fields each project to the contralateral cerebral hemispheres, but the extent of the functional overlap of the two hemifields along the vertical meridian is still under debate. After presenting the spatial, temporal, and functional specifications of Transcranial Magnetic Stimulation (TMS), we show that TMS is particularly suitable to study the question of foveal representation as it allows one to study the effects of selective disruption of left or right hemisphere functions on the processing of centrally presented stimuli. Future strategies for the use of TMS in further tests of visual word recognition are suggested.     

Hot and Cool Aspects of Cognitive Control in Children with ADHD: Decision-Making and Inhibition

This study investigated hot and cool aspects of cognitive control in children with Attention Deficit Hyperactivity Disorder (ADHD). The study aimed to: (1) replicate the postulated response inhibition deficit of children with ADHD; (2) explore whether children with ADHD choose disadvantageously in a decision-making task and to explore the mechanisms underlying the expected response pattern; and (3) study whether performance on a combination of hot and cool executive control measures has predictive value for an ADHD diagnosis. The sample consisted of 20 children with ADHD and 22 normal developing children (NC, 8 to 12 years) matched on age, FSIQ, and gender. Two paradigms have been applied: (1) the stop signal paradigm, and (2) the adapted children's version of the IOWA Gambling task. There were no group differences for both paradigms. Both groups chose in a reward-oriented manner and seemed to develop the ability to take future consequences into account in making decisions. Moreover, feedback resulted in direct behavioral changes. Children with ADHD did not have a specific response inhibition deficit or a decision-making deficit.     

Taking control of reflexive social attention

Attention is shifted reflexively to where other people are looking. It has been argued by a number of investigators that this social attention effect reflects the obligatory bottom-up activation of domain-specific modules within the inferior temporal (IT) cortex that are specialized for processing face and gaze information. However, it is also the case that top-down factors may modulate the activation of IT cells. Here we examined behaviorally whether reflexive social orienting is purely automatic or sensitive to top-down modulation. Participants were shown an ambiguous stimulus that could be perceived either as representing EYES or a CAR. In we demonstrated between groups that an automatic shift of attention, equivalent to that triggered by a schematic FACE, occurred only when the stimulus was referred to as possessing EYES. In all participants received the EYES and CAR conditions. When the stimulus was first referred to as a CAR and then as EYES, an attentional shift was only present for the EYES condition. However, when the stimulus was first referred to as possessing EYES, and then later as a CAR, attentional shifts were observed for both conditions. These data indicate that the emergence of a reflexive social attention effect is influenced by top-down mechanisms but in an asymmetrical manner. Top-down processes appear to be effective for triggering IT involvement, that is, for perceiving a stimulus as a face, which produces the social attention effect. But top-down mechanisms are ineffective once IT involvement has been triggered. That is, once a stimulus has been seen as having eyes, it continues to be seen that way, and accordingly, the social attention effect persists.     

Neuronal substrates of relapse to cocaine-seeking behavior: role of prefrontal cortex

The return to drug seeking, even after prolonged periods of abstinence, is a defining feature of cocaine addiction. The neural circuitry underlying relapse has been identified in neuropharmacological studies of experimental animals, typically rats, and supported in brain imaging studies of human addicts. Although the nucleus accumbens (NAcc), which has long been implicated in goal-directed behavior, plays a critical role in this circuit, the prefrontal cortex (PFC) appears to process the events that directly trigger relapse: exposure to acute stress, cues previously associated with the drug, and the drug itself. In this paper, we review animal models of relapse and what they have revealed about the mechanisms underlying the involvement of the NAcc and PFC in cocaine-seeking behavior. We also present electrophysiological data from PFC illustrating how the hedonic, motor, motivational, and reinforcing effects of cocaine can be analyzed at the neuronal level. Our preliminary findings suggest a role for PFC in processing information related to cocaine seeking but not the hedonic effects of the drug. Further use of this recording technology can help dissect the functions of PFC and other components of the neural circuitry underlying relapse.