中等强度情绪性图片的神经机制——一项fMRI研究

采用修订后的中等唤起度的国际情绪图片为刺激材料,以12名女性大学生为被试,考察情绪性图片引起的脑激活模式。结果发现,与中性条件相比,消极情绪图片激活了枕叶、杏仁核、海马旁回和壳核。积极情绪图片引起枕叶、内侧眶额、额中回等脑区的激活,研究结果再次验证了杏仁核与消极情绪的密切关系,同时推测,内侧眶额可能是中等唤起度的趋近性积极情绪的一个脑功能区。     

Re-emergence of extinguished auditory-cued conditioned fear following a sub-conditioning procedure: effects of hippocampal and prefrontal tetanic stimulations

Post-extinction exposure of rats to a sub-conditioning procedure can evoke conditioned fear, which may correspond to fear return and/or fear learning potentiation. The aim of the present study was to clarify this issue and examine the effects of tetanic stimulation of the hippocampus (HPC) and medial prefrontal cortex (mPFC), two brain regions implicated in post-extinction modulation of conditioned fear. Rats were initially submitted to five tone-shock pairings with either a 0.7-mA or 0.1-mA shock. Tone-evoked freezing was observed only with the higher shock intensity, indicating that the 0.1-mA shock corresponded to a sub-conditioning procedure. All conditioned rats underwent fear extinction with 20 tone-alone trials. When retrained with the sub-conditioning procedure, they displayed again tone-evoked freezing, except when the initial tone was unpaired or a new tone was paired with the 0.1-mA shock, demonstrating fear return rather than fear learning potentiation. We also found that HPC and mPFC tetanic stimulations, applied 24h after the sub-conditioning procedure, similarly reduced this fear return. However, mPFC inactivation abolished temporary HPC tetanus effect, whereas HPC inactivation did not interfere with mPFC tetanus effect. These data confirm our previous findings and reveal the nature of HPC-mPFC interactions in post-extinction modulation of conditioned fear.     

Social brain development and the affective consequences of ostracism in adolescence

Recent structural and functional imaging studies have provided evidence for continued development of brain regions involved in social cognition during adolescence. In this paper, we review this rapidly expanding area of neuroscience and describe models of neurocognitive development that have emerged recently. One implication of these models is that neural development underlies commonly observed adolescent phenomena such as susceptibility to peer influence and sensitivity to peer rejection. Experimental behavioural evidence of rejection sensitivity in adolescence is currently sparse. Here, we describe a study that directly compared the affective consequences of an experimental ostracism manipulation (Cyberball) in female adolescents and adults. The ostracism condition led to significantly greater affective consequences in the adolescents compared with adults. This suggests that the ability to regulate distress resulting from ostracism continues to develop between adolescence and adulthood. The results are discussed in the context of models of neurocognitive development.     

The effect of attending to motor overflow on its voluntary inhibition in young and older adults

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force. Overflow was concurrently recorded in the non-task hand. In the first condition, participants were not made aware of their motor overflow. Then participants, though informed of it, were asked to ignore their overflow. Finally, participants were requested to inhibit overflow with, and then without visual feedback, or vice versa. Overflow was exacerbated when older adults were unaware of it, and was reduced once they were informed. For young adults there was no significant difference between these conditions. Both Age Groups could significantly reduce overflow when so requested, independent of visual feedback. Thus motor overflow can be modulated by higher order cognitive control with directed attention.     

对威胁刺激的注意偏向：注意定向加速还是注意解除困难？

对威胁刺激的注意偏向普遍存在。注意定向加速和注意解除困难在不同阶段对注意偏向产生影响。威胁刺激属性、呈现时间以及被试特征是重要的调节因素。以杏仁核为核心的杏仁核?前扣带回网络可能是注意定向加速的神经基础, 而以眶额叶为中心的前额叶皮层可能是注意解除的神经基础。未来还需要就注意定向加速与注意解除困难的关系、注意偏向的调节机制以及其神经基础做更深入的研究。     

大脑视知觉调控的神经机制

大脑的知觉加工并非单纯由外部刺激驱动,而是存在自上而下的知觉调控。尽管这一现象被大量实验研究证实,但其神经机制仍然是认知神经科学研究的重要问题。本研究系统介绍了知觉调控的神经基础、实现形式、研究范式,及其理论模型,分析指出了当前研究面临的主要问题,并对未来的研究进行了展望,以期促进该问题研究的进一步开展。     

早期应激对情绪调节的影响及其神经机制

在个体生命早期遭遇的长期或重大的应激经历会显著增加个体罹患抑郁、焦虑等心理疾患的风险, 而情绪调节能力的损伤是引发这些心理疾患的重要因素之一。以人类为对象的行为实验和调查研究表明, 早期应激不仅会影响日常生活中情绪调节策略的使用, 还会对情绪调节能力造成影响, 其影响方向可能与早期应激的严重程度有关。目前, 大部分研究表明严重的早期应激会损伤情绪调节能力, 但中度的早期应激也可能提高情绪调节能力。更为整合性的研究表明情绪调节能力中介了早期应激和各类疾患之间的关系。进一步, 我们从神经层面上阐述了早期应激对情绪调节相关脑区和神经环路的影响。未来研究应当注意控制无关变量, 进一步探究不同早期应激对于情绪调节的影响。     

前额叶在老年阶段的可塑性及相关机制

大量研究表明, 前额叶的结构和功能更容易受年老化影响; 然而, 近年来的研究发现, 前额叶的结构和功能在老年阶段具有一定的可塑性。对老年人进行认知训练, 能够延缓前额叶皮层厚度的萎缩, 提高白质完整性, 改善神经网络的功能连接和分化, 并可能通过调节多巴胺系统的活动改变前额叶皮质和皮质下结构的功能激活模式。有氧锻炼能够改善心脑血管功能, 保护和促进神经元的存活和生长, 引起前额叶灰质、白质体积的增加及功能激活的变化。认知训练与有氧锻炼等相结合的整合性训练不仅引起前额叶及相关认知功能的改变, 而且具有更好的生态学效度, 使老年人日常认知能力和生活质量得到提高。未来研究应采用多种技术手段, 从多个层面理解老年阶段前额叶的可塑性及相关机制; 加强对与前额叶关系密切的多种认知功能可塑性神经机制的研究; 并重视与整合性训练有关的前额叶可塑性。