整体运动知觉老化伴随颞中回静息态功能改变

以个体整体运动一致性阈值为指标, 探讨老年人整体运动敏感性(GMS)下降和静息态下兴趣脑区功能活动的关系。发现与阈值负相关且老年人低于青年人的指标主要有：MT/V5区的ReHo和ALFF值, 各网络拓扑属性; 与阈值正相关且老年人显著高于青年人的有：MT/V5区与前运动皮层之间的、各兴趣脑区之间的功能连接。结果用“去分化”等观点进行了解释, 提示老年人GMS的下降可能不仅与安静状态下MT/V5区的功能改变有关, 还可能与全脑更广泛区域的功能改变有关。     

现代舞训练与弦乐训练对脑灰质体积的差异影响

目前舞蹈与音乐两种训练对脑灰质结构影响的差异尚不明确。本研究利用基于体素的形态学分析方法(voxel-based morphometry, VBM), 比较现代舞训练被试、弦乐训练被试与对照组被试的脑结构磁共振数据。结果表明现代舞训练组在涉及感觉运动控制的皮层、皮层下结构及小脑多个区域出现灰质体积的显著增加与减少; 弦乐训练组则在与音乐训练直接相关的听-动-读皮层出现灰质体积的显著增加。这一发现提示现代舞训练可能系统性地影响广泛脑区的灰质结构, 弦乐训练可能局部地改变了具体功能脑区的灰质结构, 两种训练对脑灰质结构的影响模式存在差异。     

想象膨胀范式下错误记忆的老化效应

通过2个实验探究想象膨胀范式下老年人的错误记忆特点及其认知机制。实验1采用经典想象膨胀实验范式, 考察老年人是否会产生比年轻人更大的想象膨胀错误记忆效应; 实验2引入情景特异性诱导技术, 进一步考察老年人的想象膨胀错误记忆可能的认知机制。研究结果表明：(1)老年人与年轻人均表现出显著的想象膨胀错误记忆, 但老年人并没有比年轻人产生更多的错误记忆; (2)当通过情景特异性诱导技术有效增加了老年人在事件想象过程中的内在细节数量后, 老年人的错误记忆显著上升。该结果揭示对事件情景的想象过程是想象膨胀错误记忆发生的关键环节, 老年人没有表现出明显的老化效应, 主要是由于该群体随年龄增长表现出在回忆/想象情景事件时内部细节缺乏这一特征所致。研究结果支持了建构性情景模拟假说和激活/监测理论。     

锂盐对大鼠脑单胺类和氨基酸类神经介质含量的影响

本文以111只大鼠为材料,研究了锂盐重度中毒、血清锂达2.67±0.9meq/升,小脑锂达2.05±0.92meq/kg时,脑及各脑区六种单胺类和氨基酸,类物质含量的改变。结果表明,与正常动物相比,脑多巴胺(DA)和谷氨酸(GA)含量显著下降,5-羟色胺(5-HT),5-羟吲哚醋酸,(5-HIAA)和γ-氨基丁酸(GABA)显著增高,去甲基肾上腺素(NE)虽有下降却未达显著水平。就各脑区而言,端脑DA和GA含量显著下降,5-HIAA和GABA显著升高;间脑的NE显著下降,5-HT和GABA显著升高;脑干中除GABA增高外,其他五种测定物未发生显著改变。 这一结果似乎支持了情感活动和情感性精神病的单胺假说;但它并不是锂盐作用的唯一的和特异性机制,它也引起包括脑干在内的各脑区的GABA含量的增高。     

羽毛球运动重塑成年早期的大脑灰质和白质结构

以往研究发现, 球类运动员视知觉脑区的结构不同于非运动员, 但这些脑区结构的差异是训练经历引起还是天生结构不同所导致的, 尚未可知。本研究拟采用纵向设计, 以处于成年早期的成人非运动员为被试(23~27岁), 随机分成实验组和对照组, 实验组参加12周的羽毛球运动训练, 对照组在此期间不进行任何有规律的运动训练, 采集干预实验前后所有被试的结构像和弥散张量成像数据。结果发现, 实验组训练后左下枕叶、颞中回、颞下回灰质体积增加, 双侧内囊后肢、上放射冠各向异性分数(FA)增加, 进一步分析发现, FA增加的原因是径向扩散系数(RD)下降。提示羽毛球运动可增加成人与视运动知觉有关脑区的灰质容量, 增加纤维束的髓鞘厚度。     

发展性阅读障碍的注意缺陷研究现状

近年来,发展性阅读障碍的注意缺陷研究逐渐受到重视.行为实验发现,阅读障碍者有多种注意缺陷现象,主要表现为“视野不对称性”和“注意转换延迟”.脑电研究表明,阅读障碍的注意缺陷与大脑后顶叶皮层功能异常有关.大细胞通路假设认为,阅读障碍的视知觉缺陷来源于视觉大细胞受损,大细胞通路所加工的信息主要投射到靠近颞枕顶联合区的V5MT区,这个脑区为后顶叶皮层提供大量投射.因此,阅读障碍的注意缺陷与大细胞通路受损存在一定关系.     

不同刺激条件下视听觉整合的年老化研究

研究操纵刺激通道（视觉、听觉、视听觉）与年龄（年轻人、老年人）两个自变量,要求被试对目标刺激完成检测任务,通过3个实验考察不同刺激条件对老年人视听觉整合的影响。结果发现,在静态简单刺激条件下（实验1）,老年人和年轻人的视听觉整合没有显著差异;在动态手持工具（实验2）和动态语音刺激条件下（实验3）,老年人的视听觉整合显著大于年轻人。通过对刺激条件的比较发现,年轻人和老年人在识别动态手持工具时诱发的视听觉整合最大,而且老年人的整合时间窗口会随着不同刺激条件发生改变。结果表明,视听觉整合具有很强的刺激依赖性,老年人的视听觉整合受到刺激条件的调节。     

早老性痴呆病人早期记忆损害的检测方法

采用词语延迟回忆、记忆广度和双任务工作记忆测验,研究可能用于检测(Alzheimer’s disease,AD)早期记忆损害的方法。共有4组被试：两个正常年轻人组、一个正常老年人组、一个很可能患早老性痴呆病人(Probable AD,PAD)组。结果表明：(1)正常年轻人和正常老年人的词语延迟回忆保持率没有显著差异,而PAD患者表现出明显受损;(2)两个正常年轻人组的双任务工作记忆成绩也没有显著不同,与之相比,正常老年人组有一定程度的降低,而PAD患者表现出更大程度的损害;(3)4组被试的记忆广度都不相同。这些结果提示,词语延迟回忆和双任务工作记忆测验可能能够用于检测AD早期的记忆损害。     

海洛因成瘾者的脑灰质密度下降

本研究对海洛因成瘾者（n=34）和无毒品依赖的正常被试（n=34）进行磁共振脑结构扫描,用基于体素的形态学测量（VBM）方法分析被试间灰质密度的差异,并考察了海洛因成瘾者用药时间与灰质密度之间的关系。结果表明,同正常对照组相比,海洛因成瘾者其额叶和颞叶下部的灰质密度显著下降。进一步分析显示,用药时间短于5年的成瘾者其灰质密度下降不明显,而用药时间5年以上的患者其灰质密度下降非常显著。本文讨论了上述结果的潜在临床价值和理论意义。     

老年人视听觉整合的影响因素及其神经机制

老年人的视听觉整合能力强于还是弱于年轻人, 目前尚存在很大争议。对老年人视听觉整合脑机制的研究, 将为老年人脑保健提供一种科学的跨通道整合方案。基于已有研究成果从两方面进行论述：1)影响老年人视听觉整合的因素, 包括刺激的物理属性、刺激呈现的时空关系以及刺激得到的注意资源。2)老年人视听觉整合效应。研究表明, 一方面, 老年人表现出更高的功能连接性、网络效率和较强的视听觉整合效应, 如：老年人在后顶叶、内侧前额叶和左前额叶等脑区有较强的激活, 额中央区的P2振幅表现出超加性; 老年人比年轻人的视听觉整合发生较早并有较长的延伸。另一方面, 老年人有较长的反应时和较弱的整合促进, 以及对视听觉刺激进行反应时颞上回脑区的振幅弱于年轻人。简单刺激诱发的老年人视听觉整合为进一步揭示整合机制提供了可靠的基础, 但是对于复杂情景下的视听觉信息整合加工机制仍待探究。     

Correlation between gray/white matter volume and cognition in healthy elderly people

This study applied volumetric analysis and voxel-based morphometry (VBM) of brain magnetic resonance (MR) images to assess whether correlations exist between global and regional gray/white matter volume and the cognitive functions of semantic memory and short-term memory, which are relatively well preserved with aging, using MR image data from 109 community-dwelling healthy elderly individuals. We used the Information and Digit Span subtests of the Wechsler Adult Intelligent Scale-Revised as measures of semantic memory and short-term memory, respectively. We found significant positive correlations between the gray matter ratio, the percentage of gray matter volume in the intracranial volume, and performance on the Digit Span subtest, and between the regional gray matter volumes of the bilateral anterior temporal lobes and performance on the Information subtest. No significant correlations between performance on the cognitive tests and white matter volume were found. Our results suggest that individual variability in specific cognitive functions that are relatively well preserved with aging is accounted for by the variability of gray matter volume in healthy elderly subjects.     

Finding the g-factor in brain structure using the method of correlated vectors

It is unclear whether brain mechanisms underlying human intelligence are distributed throughout the brain or mainly concentrated in the frontal lobes. Data are inconsistent possibly due, at least in part, to the different ways the construct of intelligence is measured. Here we apply the method of correlated vectors to determine how the general factor of intelligence (g) is related to regional gray matter and white matter volumes. This is a re-analysis of an earlier study showing regional gray matter and white matter volume is correlated to Full Scale IQ (FSIQ). However, it is well-known that FSIQ taps several cognitive abilities and skills in addition to g. The results now show that the g factor accounts for several but not all FSIQ/gray matter correlations distributed throughout the brain and these areas may differ for young and older adults.     

Effects of stressful life events on human brain structure: a longitudinal voxel-based morphometry study

Although stressful life events (SLEs) have been associated with an increased risk of illness and mental disorder, their impact on brain anatomy remains poorly understood. Using a longitudinal design, we tested the hypothesis that SLEs are significantly associated with changes in gray matter volume (GMV) in brain regions previously implicated in post-traumatic stress disorder (PTSD) in a group of clinically healthy adults. Magnetic resonance imaging was used to acquire an anatomical scan from 26 subjects (13 males and 13 females; mean age ± SD: 25.2 ± 4.3 years), with no psychiatric diagnosis, at two time points with a 3-month interval. Voxel-based morphometry was used to examine an association between SLEs and gray matter changes during this period. The number of SLEs was associated with a decrease in GMV in the anterior cingulate, hippocampus, and parahippocampal gyrus (p < 0.001). In contrast, there were no areas where the number of SLEs was associated with an increase in GMV. These results provide evidence that, in adults with no formal psychiatric diagnosis, SLEs are associated with GMV decreases in a subset of regions implicated in PTSD, and that these alterations can be observed within a period as short as 3 months.     

Atrophy of the parietal lobe in preclinical dementia

Cortical grey matter atrophy patterns have been reported in healthy ageing and Alzheimer disease (AD), but less consistently in the parietal regions of the brain. We investigated cortical grey matter volume patterns in parietal areas. The grey matter of the somatosensory cortex, superior and inferior parietal lobule was measured in 75 older adults (38 cognitively stable and 37 individuals with cognitive decline after 3 years). Dementia screening 6 years after scanning resulted in nine AD cases from the cognitively stable (n=3) and cognitive decline group (n=6), who were assigned to a third group, the preclinical AD group. When regional differences in cortical volume in the parietal lobe areas were compared between groups, significant differences were found between either the cognitive decline or stable group on the one hand and preclinical AD individuals on the other hand in the inferior parietal lobule. Group membership was best predicted by the grey matter volume of the inferior parietal lobule, compared to the other parietal lobe areas. The parietal lobe was characterised by a differential atrophy pattern based on cognitive status, which is in agreement with the 'last-developed-first-atrophied' principle. Future studies should investigate the surplus value of the inferior parietal lobe as a potential marker for the diagnosis of AD compared to other brain regions, such as the medial temporal lobe and the prefrontal lobe.     

The role of motion direction selective extrastriate regions in reading: a transcranial magnetic stimulation study

Why reading ability is correlated with motion processing ability is perplexing. Activity in motion direction processing regions (Area V5/MT+) was perturbed by means of repetitive transcranial magnetic stimulation (rTMS) to examine its effect on reading. A functional probe (significant shortening of the motion aftereffect) was used to identify Area V5/MT+. Right-handed participants (8 m, 8 f) received three 7.5 min blocks of rTMS, after which two phonological and one orthographic reading tasks were administered. Application of rTMS to Area V5/MT+ (as compared to a non-rTMS baseline) significantly decreased performance only during non-word naming. The pattern of naming errors and the absence of deficits on the second phonological task were not consistent with a role for Area V5/MT+ in phonological decoding. Instead, its role in reading may be limited to image stabilization and/or letter localization.     

Mapping gray matter development: Implications for typical development and vulnerability to psychopathology

Recent studies with brain magnetic resonance imaging (MRI) have scanned large numbers of children and adolescents repeatedly over time, as their brains develop, tracking volumetric changes in gray and white matter in remarkable detail. Focusing on gray matter changes specifically, here we explain how earlier studies using lobar volumes of specific anatomical regions showed how different lobes of the brain matured at different rates. With the advent of more sophisticated brain mapping methods, it became possible to chart the dynamic trajectory of cortical maturation using detailed 3D and 4D (dynamic) models, showing spreading waves of changes evolving through the cortex. This led to a variety of time-lapse films revealing characteristic deviations from normal development in schizophrenia, bipolar illness, and even in siblings at genetic risk for these disorders. We describe how these methods have helped clarify how cortical development relates to cognitive performance, functional recovery or decline in illness, and ongoing myelination processes. These time-lapse maps have also been used to study effects of genotype and medication on cortical maturation, presenting a powerful framework to study factors that influence the developing brain.     

Aging and Visual Attention

ABSTRACT— Older adults are often slower and less accurate than are younger adults in performing visual-search tasks, suggesting an age-related decline in attentional functioning. Age-related decline in attention, however, is not entirely pervasive. Visual search that is based on the observer's expectations (i.e., top-down attention) is relatively preserved as a function of adult age. Neuroimaging research suggests that age-related decline occurs in the structure and function of brain regions mediating the visual sensory input, whereas activation of regions in the frontal and parietal lobes is often greater for older adults than for younger adults. This increased activation may represent an age-related increase in the role of top-down attention during visual tasks. To obtain a more complete account of age-related decline and preservation of visual attention, current research is beginning to explore the relation of neuroimaging measures of brain structure and function to behavioral measures of visual attention.     

Neuroimaging studies in eating disorders

The understanding of the eating disorders (EDs) anorexia (AN) and bulimia nervosa (BN) has undergone remarkable advancements in the past decade. Most studies that have been done in AN show brain gray and white matter volume loss during the ill state that, at least in part, remit with recovery. Similar patterns occur for brain phospholipids assessed using magnet resonance spectroscopy (MRS). Imaging studies have been used to provide functional information regarding serotonin neuroreceptor dynamics, regional cerebral blood flow, or cerebral glucose metabolism. Such studies have implicated cingulate, frontal, temporal, and parietal regions in AN. Investigators have found that challenges such as food and body image distortions may activate some of these regions, raising the possibility that such studies may shed light on puzzling AN symptoms, such as body image distortions or extremes of appetitive behaviors. Emerging data suggest these disturbances persist after recovery from AN, suggesting the possibility that these are traits that may create a vulnerability to develop an ED. While fewer studies have been done in BN or binge eating disorder, there may be disturbances of serotonin metabolism in similar brain regions. Taken together, these findings give promise for future investigations with the hope of delineating brain pathways that contribute to the etiology of EDs