Neural correlates of subliminally presented visual sexual stimuli

In the context of forensic psychiatry, it is crucial that diagnoses of deviant sexual interests are resistant to manipulation. In a first attempt to promote the development of such tools, the current fMRI study focusses on the examination of hemodynamic responses to preferred, in contrast to non-preferred, sexual stimuli with and without explicit sexual features in 24 healthy heterosexual subjects. The subliminal stimulus presentation of sexual stimuli could be a new approach to reduce vulnerability to manipulation. Meaningful images and scrambled images were applied as masks. Recognition performance was low, but interestingly, sexual preference and explicitness modulated stimulus visibility, suggesting interactions between networks of sexual arousal and consciousness. With scrambled masks, higher activations for sexually preferred images and for explicit images were found in areas associated with sexual arousal (Stoleru, Fonteille, Cornelis, Joyal, & Moulier, 2012). We conclude that masked sexual stimuli can evoke activations in areas associated with supraliminal induced sexual arousal.     

损毁大鼠双侧内嗅皮质对束缚应激反应的影响

采用大鼠急性束缚应激动物模型,用鹅羔氨酸损毁大鼠双侧内嗅皮质来建立内嗅皮质损伤模型,观察束缚应激1小时后下丘脑室旁核快反应基因c-Fos表达情况以及应激后血浆促肾上腺皮质激素含量的动态变化,并与对照组相比较,探讨内嗅皮质与束缚应激反应的关系。结果表明,损毁内嗅皮质,明显抑制了应激诱导的下丘脑室旁核c-Fos的表达和血浆促肾上腺皮质激素含量的上升。结果提示,内嗅皮质参与调节束缚应激反应时HPA轴功能。     

工作记忆负荷对反馈加工过程的影响:来自脑电研究的证据

个体对行为后反馈结果的加工在学习和环境适应方面有重要意义,工作记忆负荷(working memory load,WM load)如何影响反馈加工过程尚不清楚。采用双任务范式,设置基线、低WM load、高WM load三种条件,结合ERP技术对这一问题进行探究。发现RewP (reward positivity,奖赏正波)对效价敏感,而不受WM load条件影响;Theta震荡的正、负反馈差异波在高WMload条件下比在低WM load条件下小。结果支持等级强化学习-前扣带回理论(HRL-ACC, hierarchical reinforcement learning theory of anterior cingulate cortex)对于RewP和theta震荡的观点:RewP反映了反馈效价评估功能, theta震荡反映了认知控制功能,并且WM load选择性影响了ACC的认知控制功能而不是反馈效价评估功能。     

激活右腹外侧前额叶提高抑郁症患者对社会疼痛的情绪调节能力：一项TMS研究

负性人际交往经历和负性社会事件是抑郁症的重要诱导因素, 而社会功能受损是抑郁症患者的重要特征之一, 患者通常表现出对社会疼痛的情绪失调。为了提高抑郁症患者在负性社交情境中或面对负性社会事件时的情绪调节能力, 本研究采用经颅磁刺激技术(transcranial magnetic stimulation, TMS), 考察抑郁症患者在腹外侧前额叶(the ventrolateral prefrontal cortex, VLPFC)被激活后其情绪调节能力的改变。结果表明, 当右侧VLPFC被TMS激活且患者采用认知重评策略调节情绪时, 实验组患者(n = 64)比对照组患者(n = 63)在社会排斥情境下报告了更弱的负性情绪体验, 这说明激活右侧VLPFC可以有效提高患者对社会疼痛的外显性情绪调节能力。本研究是采用TMS提高抑郁症患者情绪调节能力的首次尝试, 实验发现不但支持了VLPFC与认知重评策略的因果关系, 还为临床改善抑郁症等社会功能障碍患者的情绪调节能力提供了明确的神经治疗靶点。后续研究还需探讨多疗程TMS刺激方案、改变社会疼痛的诱发方式、对比左右侧VLPFC的治疗效果、尝试使用其他的情绪调节策略, 进一步验证本研究的结论, 优化TMS治疗方案。     

Noninvasive brain stimulation over M1 and DLPFC cortex enhances the learning of bimanual isometric force control

Motor learning plays an important role in upper-limb function and the recovery of lost functionality. This study aimed to investigate the relative impact of transcranial direct current stimulation (tDCS) on learning in relation to the left primary motor cortex (M1) and left dorsolateral prefrontal cortex (DLPFC) during bimanual isometric force-control tasks performed with both hands under different task constraints. In a single-blind cross-over design, 20 right-handed participants were randomly assigned to either the M1 group (n = 10; mean age, 22.90 ± 1.66 years, mean ± standard deviation) or the DLPFC group (n = 10; mean age, 23.20 ± 1.54 years). Each participant received 30 min of tDCS (anodal or sham, applied randomly in two experiments) while performing the bimanual force control tasks. Anodal tDCS of the M1 improved the accuracy of maintenance and rhythmic alteration of force tasks, while anodal tDCS of the DLPFC improved only the maintenance of the force control tasks compared with sham tDCS. Hence, tDCS over the left M1 and DLPFC has a beneficial effect on the learning of bimanual force control.     

Neuronal changes in normal human aging and Alzheimer's disease

This article discusses age-related changes in brain weight, total number of cortical neurons, cortical dendrites, spine, and synapse density. The conclusion is that the present outlook is less grim than it was 30 years ago. Age-related reduction appears to be specific to brain region and cortical layer rather than a general feature. In addition, we describe a different pattern of changes that occur in Alzheimer's disease patients. This review concludes that the association cortices in particular are affected in aging and Alzheimer's disease and that the primary visual and somatosensory cortices are relatively spared.     

Regulation of glutamate synapses by nicotinic acetylcholine receptors in auditory cortex

Acetylcholine plays an important role in regulating the processing of sensory stimuli, and understanding its specific cellular actions is critical to understanding how sensory cortex develops and functions in different behavioral states. Here we review recent work on the cellular effects of nicotinic receptor activation in auditory cortex and describe how these actions could affect systems-level auditory function. In particular, we describe a novel function of nicotinic acetylcholine receptors to regulate glutamate synapses containing N-methyl-D-aspartate receptors during early postnatal development. The transient regulation of developing glutamate synapses also defines a window of vulnerability during which exposure to exogenous nicotine disrupts synapse development. Thus, it appears that nicotinic regulation of glutamate synapses is a critical feature of auditory cortex development.     

Functional recovery of skilled forelimb use in rats obliged to use the impaired limb after grafting of the frontal cortex lesion with homotopic fetal cortex

The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.     

A Note on (K)Nots: Response to Robert W. Kentridge''s Commentary

GY, an extensively studied human hemianope, is aware of salient visual events in his cortically blind field but does not call this "vision." To learn whether he has low-level conscious visual sensations or whether instead he has gained conscious knowledge about, or access to, visual information that does not produce a conscious phenomenal sensation, we attempted to image process a stimulus s presented to the impaired field so that when the transformed stimulus T(s) was presented to the normal hemifield it would cause a sensation similar to that caused by s in the impaired field. While degradation of contrast, spatio-temporal filtering, contrast reversal, and addition of smear and random blobs all failed to match the response to a flashed bar s(f), moving textures of low contrast were accepted to match the response to a moving contrast-defined bar, s(m). Orientation and motion direction discrimination of the perceptually matched stimuli [s(m) and T(s(m))] was closely similar. We suggest that the existence of a satisfactory match indicates that GY has phenomenal vision.