Effects of tryptophan depletion on brain potential correlates of episodic memory retrieval

RATIONALE: Neuropsychological impairments in depressive illness may be secondary to proposed serotonergic abnormalities. Acute tryptophan depletion (ATD) in healthy subjects impairs episodic memory, but the mechanism of this is unclear. OBJECTIVES: To examine the effects of ATD on the neural correlates of episodic memory retrieval in healthy subjects. METHODS: Fourteen healthy men were given an amino acid cocktail drink with or without tryptophan, in a double blind, crossover design. Event related potentials (ERPs) were recorded during a well-validated episodic memory task performed 5 h after drink ingestion. Subjects listened to words spoken in a male or female voice. At test, old and new words were presented visually; subjects judged whether words were old or new, and if old, the gender of the voice at study. RESULTS: ATD led to an 84+/-5% reduction in plasma free tryptophan concentrations, and significantly impaired episodic memory recall. ERP recordings demonstrated previously reported left parietal and right frontal "old/new" differences for ERPs to items associated with accurate episodic memory retrieval versus correctly rejected new items. ATD increased ERP voltage between 500 and 1400 ms post-stimulus particularly over posterior regions of the scalp, but there was no interaction with item type. Topographical analysis of the old/new difference revealed no significant treatment by site interaction. CONCLUSIONS: ATD impairs episodic memory recall with no effect on the magnitude or topography of the neural correlates of retrieval in healthy subjects. This suggests that the effects of ATD on recall may reflect an impairment of memory encoding and/or consolidation.     

Inappropriate association of semantics and context to novel stimuli can give rise to the false recognition of unfamiliar people

This paper reports further experiments with a patient (MR) who has a tendency to claim that unfamous people are familiar together with good ability at identifying truly famous people. The first experiment examines the role that the typicality of stimuli plays in his false recognition. Although, typicality may have some influence over false recognition (as it does for normal controls) there is little evidence to suggest that MR is over-reliant on such information. It is unlikely that perceptual fluency can entirely explain his deficit. This is bolstered by a further study using morphed images of famous and unfamous faces, suggesting that false recognition is associated with inappropriate retrieval of semantic-biographical information. It is argued that MR's judgement of 'fame' is subjectively appropriate, given the information that he retrieves. This information is thought to derive from currently activated, or recently activated, contextual information which becomes inappropriately bound to the novel stimulus, giving rise to a false sense of familiarity. These findings underscore the importance of viewing memory as an attributional process, whereby current mental constructions/processes are attributed to some event(s) in the past.     

Perception of emotions from faces and voices following unilateral brain damage

The importance of the right hemisphere in emotion perception in general has been well documented but its precise role is disputed. We compared the performance of 30 right hemisphere damaged (RHD) patients, 30 left hemisphere damaged (LHD) patients, and 50 healthy controls on both facial and vocal affect perception tasks of specific emotions. Brain damaged subjects had a single episode cerebrovascular accident localised to one hemisphere. The results showed that right hemisphere patients were markedly impaired relative to left hemisphere and healthy controls on test performance: labelling and recognition of facial expressions and recognition of emotions conveyed by prosody. This pertained at the level of individual basic emotions, positive versus negative, and emotional expressions in general. The impairment remained highly significant despite covarying for the group's poorer accuracy on a neutral facial perception test and identification of neutral vocal expressions. The LHD group were only impaired relative to controls on facial emotion tasks when their performance was summed over all the emotion categories and before age and other cognitive factors were taken into account. However, on the prosody test the LHD patients showed significant impairment, performing mid-way between the right hemisphere patients and healthy comparison group. Recognition of positive emotional expressions was better than negative in all subjects, and was not relatively poorer in the LHD patients. Recognition of individual emotions in one modality correlated weakly with recognition in another, in all three groups. These data confirm the primacy of the right hemisphere in processing all emotional expressions across modalities--both positive and negative--but suggest that left hemisphere emotion processing is modality specific. It is possible that the left hemisphere has a particular role in the perception of emotion conveyed through meaningful speech.     

人工耳蜗植入和助听器配戴儿童声调识别的对比实验研究

目的探讨人工耳蜗植入儿童和助昕器配戴儿童在声调识别方面是否存在差异；考查人工耳蜗开机时间、入园康复时间，儿童的年龄、性别等因素对声调识别是否有影响。方法采用《言语听觉反应评估》（evaluation of auditory responses to speech，EARS）中的“封闭式声调测试”作为测试材料．对61名3～6岁聋儿（其中人工耳蜗植入儿童31名，助昕器配戴儿童30名）进行声调识别的测试，利用SPSS软件对结果进行统计分析。结果助昕器配戴儿童在声调识别的精确性上优于人工耳蜗植入聋儿；人工耳蜗开机时间对声调测试成绩没有明显的影响；康复时间、聋儿的年龄和声调测试成绩呈正比；聋儿的性别和声调测试成绩无关。结论助昕设备类型、康复时间、年龄等对声调识别的成绩有一定影响，这些因素之间可能存在相互作用，有待进一步探讨。     

The recognition of simple and complex realistic figures in patients with unilateral brain lesion

Summary Forty-one patients with unilateral retro-rolandic brain lesion were examined by means of three experimental tests requiring the recognition of complex realistic figures. In addition, all patients were given two tests for the recogniion of common objects and simple realistic line drawings. A set of control variables included tests for elementary visual functions, non-verbal intelligence and aphasia. Furtheron, the influence of side and hemispheric locus as well as severity of brain lesion was examined.By analyses of variance the following results were obtained: Aphasia did not play a significant role for test performance. In two of the experimental tests, the Street Test and the Hooper Test, the sub-group with right hemispheric lesion and visual field defect (VFD) was particularly impaired. It could be demonstrated, however, that this finding cannot be explained by VFD as a defect in visual function. Rather, the presence of VFD indicates a particular localization of brain lesion which is critical for the visuocognitive performances tested. For the Poppelreuter Test a significant hemispheric difference was found, right brain damaged patients performing poorer. The recognition of simple objects yielded no agnosic errors.This investigation was supported by the Deutsche Forschungsgemeinschaft.     

Task-related activity in prefrontal cortex and its relation to recognition memory performance in young and old adults

Older adults often have more widespread prefrontal cortex (PFC) activation during memory retrieval tasks, compared to young adults, particularly in the left hemisphere. Recruitment of additional frontal activity in older adults has been attributed by some researchers to compensation, perhaps for reduced activity elsewhere in the brain, whereas others have described it as a non-selective response that may be due to a failure to inhibit these PFC regions. To address further the impact of PFC activity on memory in older adults, we used PET to measure brain activity during recognition memory tasks. Both young and old adults showed increased activity during recognition, compared to a control task, in bilateral PFC. Young adults showed greater activation of left hippocampus and lateral temporal cortex during recognition, whereas older adults showed greater activity in the right inferior frontal gyrus. Age differences also were seen in correlations between brain activity and memory performance. There were positive correlations between activity in the right parahippocampal gyrus and recognition performance in young adults, whereas positive correlations between activity in PFC and performance were found only in older adults. These positive correlations included the right inferior PFC region where older adults had greater activation. Activity in this right PFC region was negatively correlated with medial temporal activity in both groups. These results provide further evidence for age-specific patterns of brain activity underlying memory performance and are consistent with the idea that PFC assumes a larger role in supporting successful recognition memory with increasing age. The negative correlation between activity in PFC and medial temporal regions, as well as the age differences in how these regions were related to behavior, suggest that those older individuals who recruit PFC to a greater degree may do so as a compensatory response to reductions in medial temporal regions.     

Visual paired comparison performance is impaired in a patient with selective hippocampal lesions and relatively intact item recognition

In this study, we have examined visual recognition memory in a patient, YR, with discrete hippocampal damage who has shown normal or nearly normal item recognition over a large number of tests. We directly compared her performance as measured using a visual paired comparison task (VPC) with her performance on delayed matching to sample (DMS) tasks. We also investigated the effect of retention interval between familiarisation and test. YR shows good visual recognition with the DMS task up to 10 s after the familiarisation period, but only shows recognition with the VPC task for the shortest retention interval (0 s). Our results are consistent with the view that hippocampal damage disrupts recollection and recall, but not item familiarity memory.     

首发与复发抑郁症患者识别悲伤面部表情的脑功能差异研究

目的 探讨首发和复发抑郁症患者识别悲伤面部表情时脑区功能的差异.方法 首发、复发重性抑郁症患者各11例,以及性别、年龄、受教育年限与患者匹配的健康对照11例入组,利用功能核磁共振成像检测受试者在识别悲伤及中性面部表情视频时的激活脑区.结果 与正常对照组相比,首发抑郁症患者识别悲伤面部表情(识别悲伤面部表情-识别中性面部表情)时活动增加的脑区有右楔叶、右梭状回、双侧额中回、左颞中回、左海马旁回(K值≥10,P<0.001),而活动降低的脑区有右颞上回、右海马旁回(K值≥10,P<0.001),复发抑郁症患者活动降低的脑区有右额下回、右颞上回(K值≥10,P<0.001),未发现活动增加的脑区;与首发抑郁症患者相比,复发抑郁症患者活动降低的脑区有右额中回、右颞上回、右中央前回、右丘脑、右屏状核(K值≥10,P<0.001),活动增高的脑区有右海马旁回、右屏状核、右岛叶(K值≥10,P<0.001).结论 抑郁症患者特别是首发抑郁症患者悲伤面部表情识别的神经基础与正常人存在差异,表现为更多的脑区参与情绪刺激的识别;复发抑郁症患者与首发抑郁症患者悲伤面部表情识别的神经基础也存在差异,表现为更多情绪识别相关脑区功能下降.     

不同性别大学生手辨识速度的差异

目的 研究旋转角度、左/右、手掌/手背三因素对手映像心理旋转处理速度的影响及其性别差异.方法 40名健康受试者(20名男性,20名女性),以0°和180°的手图片作为刺激,每次随机呈现单张手图片,需要判断呈现的图片是左手还是右手.电脑自动记录正确率和反应时.结果 ①受试者对180°图片的反应慢于0°(P＜0.01);②对O°手背图片的判断,女性反应速度快于男性[左手背:男(1033.16±245.85)ms,女(853.15 ±142.79)ms;P=0.014.右手背:男(973.07±217.11)ms,女(796.28 ±146.67)ms;P=0.016].并且对右手的反应速度快于左手,差异有统计意义(男:P=0.028,女:P=0.038).③女性对0°手背的判断[左:(853.15 ±142.79)ms,右:(796.27±146.67)ms]快于手掌[左:(1002.72±227.91)ms,右:(986.06 ±230.03)Ins],具有显著m性差异(均P＜0.01);而男性却在180°图片判断时对手背反应慢于手掌,具有统计意义(P＜0.001或＜0.01).结论 旋转角度、左/右、手掌/手背对手的心理旋转处理速度有影响,且存在着性别差异,女性反应较快.

Abstract：

Objective To investigate the gender differences and the effect of three factors(the angle of rotation, left/right,palm/back) on hand mental rotation. Methods 40 healthy adults (20 males and 20 females, age; 18～26 years) were enrolled in this study. By simulation of human hand as picture stimuli,participants were instructed to decide as quickly as possible whether the stimulus was a left or right hand. The accuracy rate and reaction time of the behavior task were quantified. Results ① the subjects' reaction speed was far slower at 180° than 0°(P＜0.01). ②On judgment of 0° back picture,females were faster than males(left back: males( 1033. 16 ±245.85) ms,females( 853.15 ± 142.79) ms,P=0.014; right back; males( 973.07 ±217.11) ms;,females (796.28 ±146.67 )ms, P = 0.016). And,the right hand was responded faster than left hand,with statistical significance (males; P = 0.028, females; P=0.038). ③The time of females in judging the 0° hand back ( left (853. 15 ± 142.79) ms,right (796. 27 ± 146. 67 ms) ) was shorter than palm(left ( 1002. 72 ± 227. 91) ms,right ( 986.06 ± 230. 03) ms), reached statistical significance ( both at P ＜ 0. 001). In contrast, males in judging the 180° pictures, the speed of reaction to back(left ( 1252. 70 ±269. 35) ms,right ( 1216. 68 ±293. 54 )ms) was slower than palm with statistical significance (left: P ＜ 0. 01, right: P = 0. 015). Conclusion The three factors (angle of rotation,left/right,and palm/back) all exert effect on the behavior of hand mental rotation. It really has gender difference on hand mental rotation. Females response faster than males.     

傅里叶变换红外光谱结合偏最小二乘模式识别方法应用于藏药麻花秦艽真伪鉴别的研究

目的:采用傅里叶变换红外光谱技术,结合化学模式识别方法,对麻花秦艽及其伪品进行鉴别分析,为麻花秦艽的质量控制提供一种新的方法。方法:采集560个来自5个不同产地的麻花秦艽及其伪品黑秦艽、甘肃丹参的原始红外光谱图,并经过多元散射校正(MSC)和二阶导数(SD)处理后,用偏最小二乘判别分析对其进行整体指纹信息判别。结果:采用的PLSDA判别分析方法,能准确成功地识别麻花秦艽及其伪品黑秦艽、甘肃丹参。结论:该法快速、准确,为客观评价中药材的真伪、产地归属、质量类别等提供了一种新的方法和手段,在中药材质量控制领域具有广阔的应用前景。