Recognition memory for emotional faces in amnestic mild cognitive impairment: An event-related potential study

ABSTRACT

This study examined the temporal course of emotional face recognition in amnestic mild cognitive impairment (aMCI). Patients and healthy controls (HC) performed a face recognition task, giving old/new responses to previously studied and novel faces displaying a negative or neutral expression. In aMCI patients, recognition accuracy was preserved for negative faces. Event-related potentials (ERPs) revealed disease-related changes in early perceptual components but not in ERP indices of explicit recognition. Specifically, aMCI patients showed impaired recognition effects for negative faces on the amplitudes of N170 and P2, suggesting deficient memory-related processing of negative faces at the stage of structural encoding and during an early recognition stage at which faces are individuated, respectively. Moreover, while a right-lateralized emotion effect specifically observed for correctly recognized faces on the amplitude of N170 was absent in aMCI, a similar emotion effect for successfully recognized faces on P2 was preserved in the patients, albeit with a different distribution. This suggests that in aMCI facilitated processing of successfully recognized emotional faces starts later in the processing sequence. Nonetheless, an early frontal old/new effect confined to negative faces and a parietal old/new effect unaffected by facial emotion were observed in both groups. This indicates that familiarity and conceptual priming processes may specifically contribute to recognition of negative faces in older adults and that aMCI patients can recruit the same retrieval mechanisms as controls, despite disease-related changes on early perceptual ERP components.     

The functional anatomy of inspection time: a pilot fMRI study

Seven healthy subjects underwent functional magnetic resonance imaging (fMRI) of the brain while performing an inspection time task. Employing a block-type design, the task had three difficulty levels: a control condition, an easy (200 ms stimulus duration), and a more difficult (40 ms) discrimination. Based on group results, there were widespread significant areas of difference in brain activation and deactivation when pairwise comparisons were conducted among the three task conditions. When the difficult condition was compared with the easy condition, there was relative activation in areas of the following brain regions: cingulate gyrus and some frontal and parietal lobe areas. Areas within the following regions showed relative deactivation (greater blood oxygenation level-dependent, BOLD, signal in the easy condition): frontal, temporal, and parietal lobe. There were overlaps between these areas and those found to be active while performing higher cognitive tasks in other functional brain imaging studies. These pilot data encourage future studies of the functional anatomy of inspection time and its relevance to psychometric intelligence.     

时间知觉的注意调节：一项ERP研究

采用双任务实验范式探讨时间知觉注意调节的动态过程。通过指导语使被试按照比例将注意分配到声音刺激的时间属性与音调属性上,形成对时间因素不同注意程度的五种注意条件,同时记录反应时、错误率和事件相关电位数据。对峰值分析发现,P2注意条件主效应不显著,但多重比较时T（只注意时间）与P（只注意音调）条件差异显著;对CNV平均波幅分析,发现注意条件主效应显著,随着分配在时间属性上的注意的减少,其波幅逐渐降低;对T与P条件的差异波地形图分析发现,波幅最大的区域位于额叶、中央区和顶叶;该差异波的偶极子定位于辅助运动区（额上回、额中回）和顶下小叶。以上结果表明,P2阶段存在时间信息加工;CNV反映时间知觉的注意调节,时间知觉中存在控制加工应该以CNV的出现为指标;辅助运动区可能为时间知觉的核心成分,具有跨通道效应;顶下小叶也与对时间的注意有关,但并不是特异性的。本研究不支持Lewis提出的 “自动”与“认知控制”计时系统理论中 “秒”为两系统分界点以及辅助运动区只属于“自动计时系统”的观点     

The extent of active processing of a long-duration stimulus modulates the scalp-recorded sustained potential

A long-duration stimulus will elicit a negative sustained potential (SP) that is maximum in amplitude over fronto-central areas of the scalp. This study examines how the duration of active attentional processing of the stimulus might also elicit a nonsensory contingent negative variation (CNV) that overlaps and summates to the SP. Subjects were presented with either a low- or high-pitched 1.4s duration stimulus. In different conditions, a 20 ms gap occurred either 300 or 1300 ms after stimulus onset in half the stimuli. The subject's task was to button press upon detection of the gap in the low-pitched stimulus. The subject was not required to respond to the gap occurring in the high-pitched tone. In a separate Ignore condition, subjects ignored all stimuli and read a book. In the Ignore condition, a SP was apparent to the long-duration stimuli. In the Attend condition, a large amplitude slow wave, probably the CNV, overlapped and summated with the SP. The extent of the overlapping CNV was dependent on whether the gap occurred early or late. The CNV was not apparent following presentation of the high-pitched tone, when the gap did not need to be detected. Consistent with previous studies, a SP was thus elicited even when active processing of the stimulus was not required. The morphology of the scalp-recorded SP was, nevertheless, much modified by an overlapping and summating CNV, depending on the extent to which active processing of the long-duration stimulus was required.     

What is perseverated in schizophrenia? Evidence of abnormal response plasticity in the saccadic system

Although perseveration is sometimes attributed to defective set switching, the authors have recently shown that set-switching is normal in schizophrenia. In this article, the authors tested for persistent states of the saccadic response system, rather than set perseveration. Schizophrenic and healthy subjects performed antisaccades and prosaccades. The authors analyzed for 3 carry-over effects. First, whereas the latency of the current saccade correlated with that of the prior saccade in both groups, the correlations under mixed-task conditions declined in healthy but not in schizophrenic subjects. Second, antisaccades in penultimate trials delayed upcoming saccades in schizophrenic but not in healthy subjects. Third, schizophrenic subjects were more likely to erroneously perseverate the direction of a prior antisaccade but not a prior prosaccade. The authors concluded that, in schizophrenia, the effects of correct antisaccades are persistent not weak. Saccades in schizophrenia are characterized by perseveration of antisaccade-induced changes in the saccadic response system rather than failures to switch task set.     

Affective valence and P300 when stimulus arousal level is controlled

Visual stimuli from the International Affective Picture System (IAPS) were employed in a modified oddball paradigm to elicit the P300 event-related brain potential (ERP) in young adult females (N=12). The pictures varied on valence (negative, neutral, positive) ratings but had the same medium arousal level ratings. The images were presented as targets with a standard stimulus composed of red/white triangles designed to mimic the spatial frequency of the pictures. P300 amplitude from negative relative to neutral stimuli was smaller over frontal areas, whereas amplitude from positive relative to neutral stimuli did not differ. P300 amplitude differences among valence categories were consistent across the midline electrodes, and did not change over the parietal area where arousal effects are typically observed. The findings suggest that valence affects P300 frontal amplitude, and arousal level should be controlled when using emotional stimuli to elicit ERPs. Theoretical implications are discussed.     

Individual differences in the effect of smoking on frontal-central distribution of the CNV: Some observations on smokers' control of attentional behaviour

A previous investigation of individual differences in cortical activation during smoking reported differential development of vertex CNV ‘O’ and ‘E’ wave components in introverted and extraverted smokers. In the present paper the frontal CNV recorded from 12 extraverted and 12 introverted smokers was analysed under simple and choice foreperiod conditions during sham and real smoking. Smokers were matched for age, sex and neuroticism. Analysis of variance revealed significant group by smoking session effects for the later ‘E’ wave component but not for the early ‘O’ wave component. ‘O’ wave negativity though more prominent in frontal regions particularly in extraverts tended to be more affected by foreperiod conditions than smoking sessions. In general smoking produced an increase in central negativity in extraverts, and a decrease in parietal positivity in introverts. These results challenge the stimulus-related/response-related separation of smoking effects made previously to account for early and late CNV component differences. It is suggested that a distinction of CNV components in terms of input (sensory) and output (motor) aspects may anyway be inappropriate.An attempt is made to relate CNV negativity/positivity topography differences to a motor model of attentional strategies differentially deployed during smoking. Extraverted smoker strategies may aim to relieve boredom, enhance readiness to act and so increase central negativity. Introverts may smoke to inhibit distraction, maintain a complex attentional set, and so these affect parietal positivity.It is further suggested that the pharmacological effects of nicotine are those of a generalized mild stressor which supplement the motor aspects of smoking in inducing more motivated performance. Some further predictions concerning the effect of smoking on cortical activity are discussed.     

不同时距加工机制的比较:来自ERP的证据(Ⅰ)

采用事件相关电位的方法分析了不同时距加工机制的差异。实验采用时间两分任务,要求被试形成短(400ms)和长(1600ms)的时间判断标准,然后对7个刺激系列进行短、长的判断。结果表明时间知觉过程可以诱发出一种类似于CNV的慢性负波。对于400ms的短时距加工存在显著的半球效应,右半球的波幅显著高于左半球。1600ms的时距加工没有表现出明显的半球效应。不同时距的加工存在显著的差异。1600ms比400ms加工诱发出更大的CNV波幅。     

ERP study of pre-attentive auditory processing in treatment-refractory schizophrenia

Event-related potential (ERP) studies have demonstrated impaired auditory sensory processing in patients with schizophrenia, as reflected in abnormal mismatch negativity (MMN). We sought to extend this finding by evaluating MMN in 13 treatment-refractory patients with schizophrenia, and 14 age- and gender-matched healthy controls. Subjects responded to infrequent visual stimulation while ignoring binaurally presented auditory tones. The amplitude and topographical pattern of the MMN were analyzed. The control group presented the expected reduction in the amplitude of the MMN from frontal to central and parietal locations. In comparison, the MMN amplitude was not reduced in the treatment-refractory patients, and was largest at the central-posterior electrode location. In addition, patients displayed larger negativities at left frontal, and left- and right-temporal electrode locations than the control subjects. These findings are consistent with pre-attentive abnormalities in treatment-refractory patients with schizophrenia.     

A quantitative near-infrared spectroscopy study: a decrease in cerebral hemoglobin oxygenation in Alzheimer's disease and mild cognitive impairment

A newly developed quantitative near-infrared spectroscopy (NIRS) system was used to measure changes in cortical hemoglobin oxygenation during the Verbal Fluency Task in 32 healthy controls, 15 subjects with mild cognitive impairment (MCI), and 15 patients with Alzheimer's disease (AD). The amplitude of changes in the waveform, which was quantitatively calculated by a signal processing method, was significantly lower in the frontal, and the bilateral parietal areas in the AD group, whereas that in the MCI group was significantly lower only in the right parietal area. The NIRS system may be a potential tool for the primary screening of AD.     

Delusions and hallucinations of cocaine abusers and paranoid schizophrenics: a comparative study

We compared delusions and hallucinations of 100 cocaine abusers and 100 paranoid schizophrenic subjects admitted to an East Texas state psychiatric hospital. Subjects in both groups feared that individuals or organized groups might harm them in some way, but delusions of the paranoid schizophrenic subjects were more often bizarre than those of the cocaine abuse subjects. "Cocaine bugs" (parasitosis) were more often found in the cocaine abuse subjects. Command hallucinations were found in both groups, but the commands of the schizophrenic group more often related to harming or killing others. Cocaine abusers had a greater frequency of visual hallucinations (47 to 7), distinguished by shadows, flashing lights ("snow lights"), objects moving and bugs crawling on the arm. Finally, the most distinguishing characteristics were identity delusions, possession delusions, grandiose delusions (other than identities and possessions), and delusions that their families were imposters (Capgras Syndrome) reported by paranoid schizophrenics. No such delusions were reported by the cocaine abusers.     

An event-related brain potential substrate of disturbed response monitoring in paranoid schizophrenic patients.

Response monitoring in schizophrenic patients and healthy controls was assessed by measuring performance and event-related brain potentials in the flanker priming task. Three visual-context conditions were construed: Flankers and targets pointed either into the same direction or into different directions. Stimuli without any response assignment were used as flankers in the neutral context condition. The schizophrenic patients were further subdivided into paranoid (n = 19) and nonparanoid (n = 10) patients and compared with healthy controls (n = 18). Performance scores revealed that the flankers induced a similar degree of distraction by visual context in all 3 groups. Although the schizophrenic patients showed normal error correction performance, the error negativity (NE) was significantly reduced in paranoid schizophrenic patients. The attenuation of the NE possibly reflects disturbed response monitoring in these patients.     

The neural basis of insight problem solving: an event-related potential study

The electrophysiological correlates of successful insight problem solving (Chinese logogriphs) were studied in 18 healthy subjects using high-density event-related potentials (ERPs). A new experimental paradigm (learning-testing model) was adopted in order to make subjects find a solution on their own initiative rather than receive an answer passively. Results showed that Successful guessed logogriphs elicited a more positive ERP deflection (P200-600) than did Unsuccessful guessed logogriphs in the time window from 200 to 600 ms after onset of the stimuli. Subsequently Successful logogriphs elicited a more negative ERP deflection than did Unsuccessful logogriphs in the time windows of 1500-2000 ms (N1500-2000) and 2000-2500 ms (N2000-2500). Maps of the P200-600 showed strong activity in the midline parieto-occipital scalp regions. Dipole analysis localized the generator of P200-600 in the left superior temporal gyrus and parietotemporo-occipital cortex areas. The N1500-2000 and N2000-2500 had a distinct activation over left frontal scalp regions. Dipole analysis localized the generator of the N1500-2000 in the anterior cingulate cortex (ACC) and the N2000-2500 in the posterior cingulate cortex (PCC). This result indicates that the parietotemporo-occipital cortex areas might be involved in forming rich associations in the early stage of successful logogriph solving. Then, the ACC might play an important role in the breaking mental set and the forming of novel associations. At last, "Aha" feeling might activate the PCC.     

理解双人肢体运动表达的友好和敌对意图的ERP证据

已有的意图理解神经成像研究大多关注理解单一个体的中性或负性意图的脑功能定位, 而大脑理解依靠双人肢体运动表达的友好和敌对意图的动态时间过程尚不清楚。本研究记录了20名健康被试完成三种不同意图推理任务时的脑电成分。三种意图分别为：1)友好意图; 2)敌对意图; 3)中性无互动意图。行为结果发现理解敌对意图的反应时最短。电生理学结果表明, 在额中区的N250 (170~270 ms)上, 中性意图比友好和敌对意图均更负, 且友好意图比敌对意图也更负; 在大脑右半球的P300 (270~450 ms)上, 敌对意图比友好和中性意图均更正, 且友好意图比中性意图也更正。对友好和敌对意图的N250和P300进行溯源分析分别定位于额中回(BA10)和脑岛(BA45)。结果表明大脑在多个阶段对双人肢体运动表达的互动意图进行分类理解, 对负性敌对意图表现出较早的理解且晚期持续性的评价加工。     

Dissociation of event-related potentials indexing arousal and semantic cohesion during emotional word encoding

Event-related potential (ERP) studies have shown that emotional stimuli elicit greater amplitude late positive-polarity potentials (LPPs) than neutral stimuli. This effect has been attributed to arousal, but emotional stimuli are also more semantically coherent than uncategorized neutral stimuli. ERPs were recorded during encoding of positive, negative, uncategorized neutral, and categorized neutral words. Differences in LPP amplitude elicited by emotional versus uncategorized neutral stimuli were evident from 450 to 1000 ms. From 450 to 700 ms, LPP effects at midline and right hemisphere frontal electrodes indexed arousal, whereas LPP effects at left hemisphere centro-parietal electrodes indexed semantic cohesion. This dissociation helps specify the processes underlying emotional stimulus encoding, and suggests the need to control for semantic cohesion in emotional information processing studies.     

双特征空间客体捆绑关系的存储机制——来自ERP的证据

利用事件相关电位技术(ERPs),采用延迟匹配任务的实验范式,测查了16名正常被试完成位置客体、方向客体和位置—方向捆绑客体的工作记忆诱发的皮层慢电位。实验发现:在第1个客体呈现后的300ms到600ms之间,在顶叶皮层(CP5、P7、P3),位置客体、方向客体比捆绑客体诱发了一个更负的成分; 在右额(F4、FC6、FC2、F8)、右后颞(TP10)、左颞(T7)、左后颞(TP9)等脑区,捆绑客体比单一特征客体诱发出了一个更正的成分; 在800至1400ms的慢波成分上,位置和方向捆绑客体在F4、FC6和F8三个记录点诱发的波形比单一特征客体的波形波幅更正。右侧前额叶参与了客体整合表征的存储,该结果支持了情景缓冲器的假设。     

A self-referential default brain state: patterns of coherence,power, and eLORETA sources during eyes-closed rest and Transcendental Meditation practice

Activation of a default mode network (DMN) including frontal and parietal midline structures varies with cognitive load, being more active during low-load tasks and less active during high-load tasks requiring executive control. Meditation practices entail various degrees of cognitive control. Thus, DMN activation patterns could give insight into the nature of meditation practices. This 10-week random assignment study compared theta2, alpha1, alpha2, beta1, beta2 and gamma EEG coherence, power, and eLORETA cortical sources during eyes-closed rest and Transcendental Meditation (TM) practice in 38 male and female college students, average age 23.7 years. Significant brainwave differences were seen between groups. Compared to eyes-closed rest, TM practice led to higher alpha1 frontal log-power, and lower beta1 and gamma frontal and parietal log-power; higher frontal and parietal alpha1 interhemispheric coherence and higher frontal and frontal-central beta2 intrahemispheric coherence. eLORETA analysis identified sources of alpha1 activity in midline cortical regions that overlapped with the DMN. Greater activation in areas that overlap the DMN during TM practice suggests that meditation practice may lead to a foundational or ‘ground’ state of cerebral functioning that may underlie eyes-closed rest and more focused cognitive processes.     

On the relationship between negative affective priming and prefrontal cognitive control mechanisms

Although several studies have examined inhibition of affective stimuli, valence-dependent cognitive control effects remain poorly understood. Behavioural and functional imaging (functional magnetic resonance imaging) data were collected from 17 healthy participants to examine neural correlates of the Negative Affective Priming (NAP) task. We created relative ratio scores considering the reaction times of prime trials in order to assess the amount of interference after the presentation of negative and positive distracter words. Behavioural results showed an attenuated NAP effect for negative distracters compared to neutral stimuli. Furthermore, priming negative distracters generated more interference by reacting to the probe target than positive distracters. Neuroimaging data revealed a stronger prefrontal activation during negative NAP trials compared to positive NAP and neutral control trials, which was reflected in a heightened activation of superior and middle frontal gyrus as well as parietal cortex. The findings show the impact of negative distracters on prefrontal response, contributing to the understanding of NAP effects in healthy subjects.     

Paranoia and Power Anxiety

Several previous studies of paranoid schizophrenia have provided only scattered support for Freud's notion that homosexual wishes and fears are the root of the difficulty. The present study was designed as a partial test of the broader theory that paranoid schizophrenia in men involves severe anxiety over aggression or assertion. The subjects were men and women in three categories: paranoid schizophrenic, nonparanoid schizophrenic, and people without any history of psychiatric trouble. Using a set of TAT cards portraying various situations of anger and aggression, it was found, as predicted, that paranoid schizophrenic men, and only paranoid schizophrenic men, show a defensive response. These findings are discussed in the context of traditional gender roles and other evidence about the paranoid style.     

The role of activation charge in an emotional categorisation task for words: insight from the perspective of a dual process theory of the activation mechanisms

The role of activation (arousal and subjective significance) was investigated for word processing in an explicit emotional judgement task using a 3?×?3 manipulation. We expected to find dissociative effects for both factors. The behavioural results showed that the fraction of words perceived as emotional increases with increasing arousal or subjective significance. The electrophysiological (EEG) results showed that both factors influence ERP amplitudes. General effects of subjective significance were found for early (60–120?ms and 120–250?ms, low subjective significant stimuli evoked higher amplitude than other conditions) and late (350–490?ms, high subjective significant stimuli evoked higher amplitude than other conditions) time ranges. Localised arousal effects were found in 250–350?ms and 350–490?ms time ranges at posterior (amplitude for high arousing stimuli was less positive than for other conditions) and left frontal ROIs (diverse pattern). Localised subjective significance effects were found for the 350–490?ms time range at the posterior ROIs (amplitude for high subjective significant stimuli was more positive than for other conditions). The results of this study suggest that the effects of arousal reported in earlier studies might account for a more complex form of activation that was recently postulated, namely subjective significance.