健康人脑空间工作记忆的脑功能磁共振研究

目的 通过功能磁共振成像(unctional magnetic resonance imaging, fMRI)技术研究健康人脑空间工作记忆的功能脑区.方法 10名右利手健康志愿者进行空间工作记忆任务的同时进行fMRI扫描,实验采用组块设计和SPM99软件进行数据分析和脑功能区定位.结果 大脑皮质所激活的主要脑区有双侧顶叶(BA7/40,BA:Brodmann area,布鲁德曼分区),双侧额叶(BA6/9/47),双侧枕颞交界处(BA19/37);被激活的大脑皮质下结构有右侧尾状核、左侧丘脑和左侧中脑黑质;双侧小脑也均被显著激活(P<0.001).结论 人脑处理空间工作记忆信息是由大脑皮质下结构及小脑与大脑皮质共同完成的.     

汉语单字词音、义加工的脑激活模式

目的:研究汉字音、义加工的脑机制.方法:采用汉字单字词为实验材料,通过功能磁共振成像扫描执行语音和语义两种认知任务的脑区.结果:语音任务激活的脑区有,左侧顶叶下部和颞上回(BA 40/39/22,BA:Brodmann Area,即布鲁德曼分区,下同),左侧枕中回(BA 18/19),右侧枕下回(BA 18/19),以及左中央前回(BA6).语义任务激活的脑区有,左侧顶叶下部(BA 40/39)和左侧颞上回(BA 22),左侧额下回(BA 10/47),右侧额中回和额上回(BA 10/11),以及左侧额中回(BA 11).语义任务减去语音任务激活的脑区有,左侧额下回(BA47),左侧海马(BA 36)和右侧海马旁回(BA 36).语音任务减去语义任务没有发现任何脑区的显著激活.结论:在语义任务中与语音有关的脑区得到激活;而在语音任务中与语义有关的脑区没有激活.     

汉语单字词音、义加工的脑激活模式

目的：研究汉字音、义加工的脑机制。方法：采用汉字单字词为实验材料，通过功能磁共振成像扫描执行语音和语义两种认知任务的脑区。结果：语音任务激活的脑区有，左侧顶叶下部和颞上回(BA 40／39／22，BA：Brodmann Area，即布鲁德曼分区，下同)，左侧枕中回(BA18／19)，右侧枕下回(BA18／19)，以及左中央前回(BA6)。语义任务激活的脑区有，左侧顶叶下部(BA40／39)和左侧颞上回(BA22)，左侧额下回(BA10／47)，右侧额中回和额上回(BA10／11)，以及左侧额中回(BA11)。语义任务减去语音任务激活的脑区有，左侧额下回(BA47)，左侧海马(BA36)和右侧海马旁回(BA36)。语音任务减去语义任务没有发现任何脑区的显著激活。结论：在语义任务中与语音有关的脑区得到激活；而在语音任务中与语义有关的脑区没有激活。     

语义记忆脑功能区偏侧化的功能磁共振成像研究

目的 通过功能磁共振成像(fMRI)技术检测健康人脑语义记忆功能区的分布特点.方法 14名右利手健康志愿者进行配对词语联想学习记忆任务时行fMRI扫描,该任务可有代表性地反映受试者的语义记忆.实验采用组块设计并选用SPM99软件行数据分析和脑功能区定位,记录各激活脑区的像素值并计算偏侧化指数LI值.结果 经单样本t检验,阈值设为P＜0.005时,记忆编码时主要激活脑区为左枕叶和左额上中回,提取时主要激活左顶叶、左枕叶和左额中下回;而右半球在两阶段均较少激活.编码和提取激活脑区像素值LI值分别为0.81和0.73.结论 语义记忆的脑功能区有显著的左半球优势;记忆编码和提取阶段所激活的脑区有所差别,但均主要分布于左外侧裂语言区的周围.     

睡眠剥夺影响数字记忆的功能磁共振成像研究

研究背景长时间连续作业易导致大脑疲劳,已有证据显示脑疲劳对作业者认知功能和行为反应能力具有严重损害作用,因此揭示连续作业和睡眠剥夺对认知功能影响的机制,有助于对抗连续作业所致疲劳,提高连续作业能力。本研究通过分析睡眠剥夺前后功能磁共振成像(fMRI)特点,探讨睡眠剥夺影响学习记忆的神经机制。方法共6例健康男性志愿者接受48h睡眠剥夺,采用组块设计方法评价睡眠剥夺前后数字记忆功能变化,fMRI比较数字记忆编码、维持和提取阶段各脑区的激活特点。结果睡眠剥夺48h,受试者对4～7个0～9数字记忆的错误率并未增加(均P>0.05);对4～6个0～9数字记忆的反应时间与睡眠剥夺前无明显差异(均P>0.05),仅7个0～9数字记忆的反应时间增加(P=0.005)。睡眠剥夺后激活减弱的脑区在数字记忆试验编码阶段为左侧海马旁回Brodmann30区、颞上回Brodmann42区、岛叶Brodmann41区和额叶Brodmann6区;在维持阶段分别为左侧颞上回Brodmann38区、颞中回Brodmann21区、海马旁回和杏仁核Brodmann30区、额中回Brodmann47区、豆状核和丘脑,以及右侧豆状核、左侧扣带后回Brodmann30区、右侧扣带后回Brodmann30区、双侧扣带回Brodmann24区、双侧额中回和额内侧回Brodmann6区;提取阶段包括双侧海马、右侧杏仁核和顶下小叶Brodmann40区、左侧楔前叶Brodmann19区和丘脑。结论在数字记忆的不同阶段,机体通过激活不同的脑区来维持清醒状态,48h睡眠剥夺后参与数字记忆的大脑皮质及皮质下结构广泛受损。     

反社会人格障碍患者的脑灰质结构研究

目的 研究反社会人格障碍(APD)患者与正常人大脑灰质结构的异同.方法 对17例APD患者(APD组)和19名与APD组的年龄、性别、智商及文化程度匹配的正常对照者(正常对照组)进行脑部T1加权像及3维结构像扫描,并使用基于体素的形态学分析法进行数据分析.结果 APD组左额上回(BA8)、右楔前叶、左眶额回、双侧额中同、右额内侧同、右侧顶下小叶、左梭状回、双侧颞上回及双侧小脑的灰质密度低于正常对照组,而左额上回(BA38)及左海马旁回的密度高于正常对照组(P<0.005).结论 APD患者存在脑结构的异常,主要包括前额叶、眶额回、楔前叶、颞叶及双侧小脑.     

反社会人格障碍患者的脑灰质结构研究

目的 研究反社会人格障碍(APD)患者与正常人大脑灰质结构的异同.方法 对17例APD患者(APD组)和19名与APD组的年龄、性别、智商及文化程度匹配的正常对照者(正常对照组)进行脑部T1加权像及3维结构像扫描,并使用基于体素的形态学分析法进行数据分析.结果 APD组左额上回(BA8)、右楔前叶、左眶额回、双侧额中同、右额内侧同、右侧顶下小叶、左梭状回、双侧颞上回及双侧小脑的灰质密度低于正常对照组,而左额上回(BA38)及左海马旁回的密度高于正常对照组(P<0.005).结论 APD患者存在脑结构的异常,主要包括前额叶、眶额回、楔前叶、颞叶及双侧小脑.     

反社会人格障碍患者的脑灰质结构研究

目的 研究反社会人格障碍(APD)患者与正常人大脑灰质结构的异同.方法 对17例APD患者(APD组)和19名与APD组的年龄、性别、智商及文化程度匹配的正常对照者(正常对照组)进行脑部T1加权像及3维结构像扫描,并使用基于体素的形态学分析法进行数据分析.结果 APD组左额上回(BA8)、右楔前叶、左眶额回、双侧额中同、右额内侧同、右侧顶下小叶、左梭状回、双侧颞上回及双侧小脑的灰质密度低于正常对照组,而左额上回(BA38)及左海马旁回的密度高于正常对照组(P<0.005).结论 APD患者存在脑结构的异常,主要包括前额叶、眶额回、楔前叶、颞叶及双侧小脑.     

反社会人格障碍患者的脑灰质结构研究

目的 研究反社会人格障碍(APD)患者与正常人大脑灰质结构的异同.方法 对17例APD患者(APD组)和19名与APD组的年龄、性别、智商及文化程度匹配的正常对照者(正常对照组)进行脑部T1加权像及3维结构像扫描,并使用基于体素的形态学分析法进行数据分析.结果 APD组左额上回(BA8)、右楔前叶、左眶额回、双侧额中同、右额内侧同、右侧顶下小叶、左梭状回、双侧颞上回及双侧小脑的灰质密度低于正常对照组,而左额上回(BA38)及左海马旁回的密度高于正常对照组(P<0.005).结论 APD患者存在脑结构的异常,主要包括前额叶、眶额回、楔前叶、颞叶及双侧小脑.     

反社会人格障碍患者的脑灰质结构研究

目的 研究反社会人格障碍(APD)患者与正常人大脑灰质结构的异同.方法 对17例APD患者(APD组)和19名与APD组的年龄、性别、智商及文化程度匹配的正常对照者(正常对照组)进行脑部T1加权像及3维结构像扫描,并使用基于体素的形态学分析法进行数据分析.结果 APD组左额上回(BA8)、右楔前叶、左眶额回、双侧额中同、右额内侧同、右侧顶下小叶、左梭状回、双侧颞上回及双侧小脑的灰质密度低于正常对照组,而左额上回(BA38)及左海马旁回的密度高于正常对照组(P<0.005).结论 APD患者存在脑结构的异常,主要包括前额叶、眶额回、楔前叶、颞叶及双侧小脑.     

Memory for the September 11, 2001, terrorist attacks one year later in patients with Alzheimer's disease, patients with mild cognitive impairment, and healthy older adults

Although there are many opportunities to study memory in patients with Alzheimer's disease (AD) in the laboratory, there are few opportunities to study memory for real world events in these patients. The September 11, 2001 terrorist attacks provided one such opportunity. Patients with AD, patients with mild cognitive impairment (MCI), and healthy older adults were given a telephone questionnaire in the initial weeks after the event, again three to four months later, and finally one year afterwards to evaluate their memory for the September 11, 2001 terrorist attacks. We were particularly interested in using the attacks as an opportunity to examine the decline of episodic memory in patients with AD, patients with MCI, and older adult controls over a period of months. We found that compared to healthy older adults, patients with AD and MCI showed impaired memory at the initial time point, more rapid forgetting from the initial to the three-month time point, and very similar changes in memory from the three-month to the one-year time point. We speculated that these findings were consistent with patients with AD and MCI showing initial impaired encoding and a more rapid rate of forgetting compared with healthy older adults, but that once the memories had been consolidated, their decay rate became similar to that of healthy older adults. Lastly, although memory distortions were common among all groups, they were greatest in the patients with AD.     

Selective neurotoxic damage to the hippocampal formation impairs performance of the transverse patterning and location memory tasks in rhesus macaques

Monkeys with neurotoxic (ibotenic acid) damage to the hippocampal formation and unoperated controls were trained on two sets of transverse patterning problems (A+/B-, B+/C-, C+/A-, and D+/E-, E+/F-, F+/D-) and a delayed nonmatching-to-location paradigm (DNML) with delays of 10s, 30s, 120s, and 600s. Hippocampal lesions produced a size- and area-dependent impairment on transverse patterning. Damage largely limited to the right hippocampus in one subject had no effect on performance on the task. Of the remaining four subjects, two with hippocampal damage greater than 40% bilaterally were unable to solve the two transverse patterning sets, but could solve the linear set of discriminations (A+/B-, B+/C-, C+/X-). The two remaining operated animals were impaired in acquisition of both sets, but were eventually able to solve one of the two transverse patterning discrimination sets. All five operated monkeys were impaired relative to normal controls on DNML, but not on the standard delayed nonmatching-to-sample (DNMS) version with trial-unique objects. The results confirm our previous findings (Alvarado et al., Hippocampus 12:421-433, 2002) using aspiration lesions of the hippocampal formation and strengthen the view that the hippocampal formation is critical for object and spatial relational memory.     

A macaque remembers pictures briefly viewed six months earlier

While there are several studies documenting the enduring nature of memory for acquired discriminatory "habits' or "skills' in animals, comparable data on memory for visual scenes, i.e., "events', are essentially non-existent, and difficult to obtain even in man. An opportunity to assay this question in macaques arose in the early stages of training an animal on a running recognition task. It had previously been trained on trial-unique delayed matching to sample, and its past experience with this visual material was precisely known. When some of these images which had not been seen by the monkey for at least 6 months were intermingled with comparable material during its training on the running recognition task, with a high degree of statistical reliability (P less than 0.005) it distinguished about one-third of the earlier images, many of which had been seen for a total of only 30 s or less. A medical student, who had previously trained the animals and had had more exposure to the material than did this macaque, and certainly had more precise instruction on how to perform, recognized two-thirds of these same images, also after a hiatus of 6 months. It thus appears likely that the permanence of mnemonic storage for briefly encountered scenes is comparable for the central visual systems of macaque and man.     

Human hippocampal‐dependent tasks: Is awareness necessary or sufficient?

The hippocampus has been shown to be required for the acquisition of declarative or explicit memory. Whether all hippocampal-dependent forms of learning and memory are explicit is an open question. Controversy has emerged about the existence of implicit hippocampal-dependent tasks. Two implicit tasks that may involve the hippocampusare a relational eye tracking task (Ryan et al. (2000) Psychol Sci 11:454-461) and transitive inference (Greene et al. (2006) J Cognit Neurosci 18:1156-1173; Greene et al. (2001) Mem Cognit 29:893-902). Recently, it was shown that both of these tasks may depend upon task awareness (Smith et al. (2006) J Neurosci 26:11304-11312; Smith and Squire (2005) J Neurosci 25:10138-10146). It is argued that in both cases, distinct, explicit versions of the tasks were created, which do not disprove the implicit nature of the original tasks.     

Effects of temporal lobe epilepsy on retrograde memory

PURPOSE: In a previous investigation (Lah et al., 2004), we found deficits in retrograde memory in patients who had undergone temporal lobectomy (TL). In this study, we set out to determine whether such deficits are present before surgery in patients with temporal lobe epilepsy (TLE). METHODS: Memory for public and autobiographic facts and events was assessed in patients with focal left-sided (n=15) or right-sided (n=14) TLE and healthy control subjects (n=15). The impact of epilepsy and underlying cognitive deficits on retrograde memory also was examined. RESULTS: Patients with left TLE demonstrated retrograde memory deficits across domains. Patients with right TLE showed defective recall only in the autobiographic domain. Young age at onset (younger than 14 years) was associated with greater difficulties in recall of famous events, and patients receiving polytherapy had significantly reduced recall of autobiographic events compared with those receiving monotherapy. In most cases, deficient memory for the past was associated with impairments in other cognitive skills, especially language abilities. CONCLUSIONS: In unoperated-on patients with TLE, we found deficits in retrograde memory that were similar to those seen after TL, with the pattern of deficits being influenced by side of lesion, anticonvulsant medication, and word-finding deficits. Unlike patients tested after right TL, patients with right TLE did not have difficulty recalling details of famous events, which raises the possibility that right TL results in a decline in this aspect of retrograde memory.     

Dissociating prefrontal contributions during a recency memory task

Neuroimaging studies of normal young adults have consistently found right prefrontal cortex (RPFC) activity during the performance of recency memory tasks. However, it is unclear whether the involvement of RPFC during these tasks reflects retrieval processes or executive processes such as: strategic ordering or monitoring. In the current study, we distinguish between those PFC regions that are more related to retrieval processes, versus strategic ordering processes. An event-related fMRI study was conducted in which eight young subjects were scanned while performing verbal episodic retrieval tasks (recognition and recency memory tasks), and verbal non-memory strategic organizing control tasks (reverse alphabetizing of words). The fMRI results show that young subjects engaged right dorsolateral PFC during recency and reverse alphabetizing control tasks. Left ventral PFC was engaged across all tasks; however, a subset of voxels within this region was more active during retrieval tasks. Left dorsolateral and right ventral PFC activity was more related to the performance of reverse alphabetizing tasks, respectively. We conclude that right dorsolateral PFC activity during recency memory reflects more general strategic organizational or monitoring processes, and is not EM-specific.     

A preliminary study of the different memory systems in neurofibromatosis type 1: What is impaired and what is spared?

BackgroundSince 1990's, the cognitive profile of children with a neurofibromatosis type 1 (NF1) has been refined by many different studies. Children with NF1 may exhibit a variety of cognitive dysfunctions. Memory difficulties have been reported, but the results are contradictory and, compared to other cognitive functions, memory has been less evaluated.ObjectiveThe aim of this study was to investigate the memory profile in NF1 with a particular population, children with NF1 without attention deficit hyperactivity disorder (ADHD).MethodsEighteen children with NF1 without ADHD and eighteen typically developing aged from 8 to 12.6 years were compared in terms of both their verbal and visual working memory, anterograde memory, and procedural perceptual-motor memory. We also assessed semantic and autobiographical memory.ResultsOur results indicate the existence of memory difficulties in children with NF1 without ADHD in verbal working and anterograde memory but not in terms of the visual domain. They also experienced difficulties recalling personal memories but these were improved by cueing. However, semantic memory and procedural perceptual-motor memory was preserved.ConclusionsThese results highlight a difference between memory systems in children with NF1 without ADHD and the importance to assess the different memory systems, the nature of information and the processes in long-term memory in NF1 population. However, our results raise questions about the possible links between these difficulties and the executive functions. The specifics of memory profile in children with NF1 must be taken into consideration in these children’s clinical follow-up, in order to understand their learning difficulties and to make adaptations to their care.     

Absolute and relative temporal order memory for performed activities following stroke

Reconstructing the temporal order of events is a crucial part of episodic memory. The temporal dimension, however, is often discarded in clinical settings, and measurements of true temporal aspects of episodic memory are scarce. The present study assessed temporal memory in stroke patients and in age- and education-matched healthy controls. Both groups underwent a standardized neuropsychological examination. We asked participants afterwards to reconstruct the order of tests they had performed, measured in absolute temporal order (event placed on correct moment in sequence) and relative temporal order (event placed correctly relative to directly preceding and following events). The aim of the study was to examine how serial-position curve effects (measuring absolute temporal order anchored in exact time) and how relative temporal order memory (anchored to other events) may differ in a group of cerebral stroke patients. Another aim was to link temporal order memory deficits with established neuropsychological measures of cognitive functioning. Although item identification was comparable in both groups, absolute temporal order memory was impaired in patients: A total of 43% of the patients lacked the expected primacy and recency effects (serial position effect). In addition, relative temporal order memory was affected in this group as well, F(1, 70) = 4.08, p < .05; 25% of the patients were impaired in reconstructing the relative temporal order (p = .019, Fisher’s Exact Test). Both absolute and relative temporal order memory performance related to the domains of executive functioning and memory. Our results suggest that it is important to test both absolute and relative temporal order memory, especially because these types of memory depend on different anchors, either on time or on adjacent events.     

Randomized controlled trial evaluating the temporal effects of high‐intensity exercise on learning,short‐term and long‐term memory,and prospective memory

The broader purpose of this study was to examine the temporal effects of high‐intensity exercise on learning, short‐term and long‐term retrospective memory and prospective memory. Among a sample of 88 young adult participants, 22 were randomized into one of four different groups: exercise before learning, control group, exercise during learning, and exercise after learning. The retrospective assessments (learning, short‐term and long‐term memory) were assessed using the Rey Auditory Verbal Learning Test. Long‐term memory including a 20‐min and 24‐hr follow‐up assessment. Prospective memory was assessed using a time‐based procedure by having participants contact (via phone) the researchers at a follow‐up time period. The exercise stimulus included a 15‐min bout of progressive maximal exertion treadmill exercise. High‐intensity exercise prior to memory encoding (vs. exercise during memory encoding or consolidation) was effective in enhancing long‐term memory (for both 20‐min and 24‐h follow‐up assessments). We did not observe a differential temporal effect of high‐intensity exercise on short‐term memory (immediate post‐memory encoding), learning or prospective memory. The timing of high‐intensity exercise may play an important role in facilitating long‐term memory.