P300 and Recall in an Incidental Memory Paradigm

In previous research Karis, Fabiani, and Donchin (1984) found a relationship between the amplitude of the P300s elicited by words and subsequent recall performance. Words later recalled elicited larger P300s than words later not recalled. However, this relationship was dependent on the mnemonic strategies used by the subjects. There was a strong relationship between P300 amplitude and recall when rote rehearsal strategies were used, but when subjects used elaborative strategies the relationship between P300 amplitude and recall was not evident. In the present experiment we employed an incidental memory paradigm to reduce the use of rehearsal strategies. An “oddball’ task consisting of a series of names was presented, and subjects were required to count either the male or the female names. Event-related brain potentials were recorded to the presentation of each name. Following the oddball task, subjects were asked, unexpectedly, to recall as many names as possible. The names that were recalled had elicited, on their initial presentation, larger P300s than names not recalled. Thus, these results confirm our hypothesis: when elaborative rehearsal strategies are not used, the relationship between P300 and memory emerges more consistently. Our data provide support for a “context updating’ hypothesis of the functional significance of the P300.     

面孔表情的ERP研究进展

情绪 (emotion)是情感的外部表现 ,是人们适应性的一种表现 ,也构成了一个基本的动机系统。面孔是人类表达、认知情感的重要工具和途径 ,正确的表达和识别面部表情是人类生存的一项重要的技能。人们运用各种手段研究面孔、情绪、大脑及其与其他认知方面的关系 ,本文总结了前人利用事件相关电位 (ERP)技术研究面孔和情绪的方法、结果、影响因素并且对面孔及情绪的ERP研究提出问题并做出了展望。     

Interhemispheric Difference for Upright and Inverted Face Perception in Humans: An Event-Related Potential Study

We recorded event-related potentials (ERPs) to investigate the interhemispheric difference of the N170 component for upright and inverted face perception in detail in fifteen healthy subjects. This is the first ERP study focusing on interhemispheric differences for face perception by showing faces in the hemifield. The face inversion effect, the prolonged latency and enhanced amplitude were found in both hemispheres. We found that the peak latency of the N170 following both upright and inverted face stimulation showed no significant difference between each hemisphere, though the N170 latency for the inverted face in the left hemisphere was shorter than that in the right hemisphere. The N170 recorded from the hemisphere ipsilateral to the stimulated hemifield showed unique findings. The interhemispheric time difference of the N170 between the right and the left hemispheres when the inverted face was presented in the left hemifield was significantly shorter than in the other three conditions. This unique finding may indicate that the conduction time from the right to the left for inverted face perception is faster than the other conditions, or that the left hemisphere specifically processed the inverted face very rapidly after receiving signals from the right hemisphere. If the N170 was generated by some, at least two, temporally overlapping activities, the different style of a summation of these activities may cause the unique findings found in this study. In conclusion, by presenting face stimuli in the hemifields, we could identify several new findings regarding the N170 component related to the face inversion effect.     

The utility of brief,spectrally rich,dynamic sounds in the passive oddball paradigm

Experiments investigating auditory processing often utilize spectrally rich, dynamic stimuli to simulate an ecologically valid auditory environment in the laboratory. Often, however, these stimuli do not allow for a strict control of the timing of auditory sensory information which may be distributed over the whole duration of a given sound. In the present study, brief (20 ms long), dynamic, spectrally rich sounds were presented in the context of a passive oddball paradigm to young adults. The short duration made certain that the sensory information was delivered entirely within a 20 ms interval. Two sounds were presented as standards (45–45% probability), other two as deviants (5–5% probability) in random sequences, with a stimulus onset asynchrony (SOA) of 1500 ms. Deviants elicited the mismatch negativity and late difference negativity (LDN) event-related potential components. No N1-effect was produced by deviants, which suggests that the acoustic energy is spread over many different features due to the dynamic spectral properties, which, combined with the brief duration, causes insignificant refractoriness-effects at the present SOA. These results support the usefulness of brief natural sounds in auditory research. The elicitation of LDN in an adult group was an unexpected finding, because LDN is mostly found in children, but not in adults. This result might indicate that LDN elicitation depends on stimulation complexity: stimulus settings in which an LDN is registered in children but not in adults may be perceived as more complex by children than by adults.     

Single Trial Analysis of Neurophysiological Correlates of the Recognition of Complex Objects and Facial Expressions of Emotion

In an earlier experiment, we have used the BTi twin MAGNES system (2 × 37 channels) to record the evoked magnetic field from five healthy right-handed male volunteers using two tasks: visual recognition of complex objects including faces and facial expressions of emotion. We have repeated the experiment with one of the five subjects using the BTi whole head system (148 channels). Magnetic field tomography (MFT) was used to extract 3D estimates of brain activity millisecond by millisecond from the recorded magnetoencephalographic (MEG) signals. Results from the MFT analysis of the average signals of the five subjects have been reported elsewhere (Streit et al. 1997; Streit et al. 1999). In this paper, we present results of the detailed single trial analysis for the subject recorded from the whole head system. We found activations in areas extending from the occipital pole to anterior areas. Regions of interest (ROIs) were defined entirely on functional criteria and confirmed independently by the location of the maximum activity on the MRI. Activation curves for each ROI were computed and objective statistical measures (Kolmogorov-Smirnov test) were then used to identify time segments for which the ROI activity showed significant differences both within the same and across different object/emotion categories. Emphasis is placed on the quantification of the activity from two ROIs, fusiform gyrus (FG) and amygdala (AM), which have been best studied in the context of processing of faces and facial expressions of emotion, respectively. We found no face-specific area as such, but instead areas like the FG was activated by all complex objects at roughly similar latencies and varying strengths. The amygdala activity was significantly different between 150 and 180 ms for fearful expression, and even earlier for happy expression.     

The effects of response sharing and stimulus presentation frequency on event‐related potentials in an auditory oddball paradigm

An experimental model for investigating the processes involved in reacting to unpredictable events is the oddball paradigm. We investigated how the commonality or independence of response options (i.e., many‐to‐one vs. one‐to‐one stimulus‐response mappings) influences processing in an auditory oddball paradigm. Participants performed a discrimination task with two one‐to‐one and one two‐to‐one mappings. The pattern of conflict‐ and oddball‐related N2 event‐related potentials suggest that information that would allow correct responding is represented at the latency of the N2. Integration of this information takes place only by the latency of P3b, and longer reaction times to rare stimuli are probably due to processes preventing the utilization of this information. We also suggest that, in the given task context, conflict‐related N2 may reflect the number of alternative stimuli leading to alternative response options.     

面部表情识别的影响因素:面部特征及观察者特性

面部表情识别受到了交流双方的多种因素的影响。本文首先从表情发出者的角度,介绍了面部本身的特性(包括特定部位和整体的特征信息)对面部表情识别的影响;接着从信息接收者的角度,介绍了观察者自身的特性(如所处的情绪状态、内部思维线索、性别、年龄、文化背景等)对面部表情识别的影响;最后,对未来研究中如何改进实验设计、扩展研究问题提出了建议。     

Spatio-temporal Modeling of Evoked Brain Activity During Memory Encoding and Target Comparison in Visual Tasks

In this paper, the temporal pattern of activity and approximate locations of brain areas related to selective attention and visual working memory processes were studied with event related potential (ERP) recordings in healthy humans. Three experimental series included pairs of the following conditions: Face comparison (familiar faces), Pattern comparison (abstract dot patterns), and Passive viewing. Participants compared pairs of consecutive targets presented in composite images on a computer screen. Spatio-temporal multiple dipole models were developed for 128-channel ERPs. Keeping dipole locations and orientations constant, we compared the source activities for ERPs recorded (1) in different tasks for task-specificity of activations, (2) after the first and second stimuli in the pair, i.e. on the encoding and comparison stages of the task, and (3) after the first stimulus in different series to compare encoding in different conditions. Sources located in the inferotemporal brain areas, especially in the left hemisphere, showed increased activity after 200 ms from the first stimulus onset that may indicate encoding into visual working memory. The anterior sources, located near midline and showing activity around or after 300 ms, presumably reflect non-specific memory processes and attentional control. Major task-specific differences were observed in the temporo-parieto-occipital region in 250–500 ms.     

Detecting violations of temporal regularities in waking and sleeping two-month-old infants

Correctly processing rapid sequences of sounds is essential for developmental milestones, such as language acquisition. We investigated the sensitivity of two-month-old infants to violations of a temporal regularity, by recording event-related brain potentials (ERPs) in an auditory oddball paradigm from 36 waking and 40 sleeping infants. Standard tones were presented at a regular 300 ms inter-stimulus interval (ISI). One deviant, otherwise identical to the standard, was preceded by a 100 ms ISI. Two other deviants, presented with the standard ISI, differed from the standard in their spectral makeup. We found significant differences between ERP responses elicited by the standard and each of the deviant sounds. The results suggest that the ability to extract both temporal and spectral regularities from a sound sequence is already functional within the first few months of life. The scalp distribution of all three deviant-stimulus responses was influenced by the infants’ state of alertness.     

Effects of anxiety on the processing of fearful and happy faces: an event-related potential study

This study investigated the influence of trait anxiety on event-related potentials (ERPs) to fearful, happy, and neutral faces. Fearful faces, relative to neutral, elicited a range of effects in the low-trait anxiety (LTA) group: an enhanced visual P1 component, an early posterior negativity (EPN), and a sustained fronto-central positivity. Emotional expression effects were generally weaker for happy faces. The enhanced fronto-central positivity and EPN triggered by fearful stimuli in LTA participants were less pronounced in the high-trait anxiety (HTA) group, while the enhancement of the visual P1 seen in the LTA group was further augmented in the HTA group. This represents a clear dissociation across anxiety groups between rapid attentional processing as reflected by the visual P1 and later strategic processing as reflected by fronto-central and EPN components. These effects of high-trait anxiety in potentiating initial threat evaluation but attenuating later cognitive processing are discussed in the context of the possible roles of neural systems underlying threat evaluation, cognitive avoidance, and differentiated affective responses.     

正常成人在面孔识别过程中的脑事件相关电位特征

目的:应用脑事件相关电位(ERP)技术对于人的面孔识别机制进行研究,为评价早期认知功能障碍提供依据。方法:对30名正常志愿者进行面孔识别ERP实验,使用E-Prime软件进行面孔和房子等刺激目标的程序编辑,采用64导Neuroscan脑电信号采集系统进行脑电信号采集,并用Curry 7软件进行离线数据分析,应用SPSS17.0统计软件包统计学分析。结果:P100波幅的性别主效应显著(F=9.529,P0.01),刺激类型主效应显著(F=7.365,P0.01)。P100的潜伏期性别主效应显著(F=6.967,P0.01),刺激类型主效应显著(F=13.270,P0.01)。N170潜伏期的性别主效应显著(F=48.356,P0.01),波幅和潜伏期的刺激类型主效应也均显著(F=36.782,38.309;P0.01),其中面孔刺激的波幅和潜伏期均大于房子(-8.847±4.453、-6.787±4.730μv,162.356±13.834、148.352±16.917ms;F=74.243,75.140;P0.01),倒立面孔波幅和潜伏期均大于正立面孔(P=0.010,0.020),但倒立房子的波幅和潜伏期与正立房子均无显著差异(P0.05)。VPP波幅的刺激类型主效应显著(F=58.104,P0.01),电极部位主效应显著(F=9.136,P0.01)。N300波幅的性别主效应显著(F=10.936,P0.01),刺激类型主效应显著(F=4.595,P0.01),电极部位主效应也显著(F=6.396,P0.01)。结论:给予面孔视觉刺激后,首先同时在两侧大脑枕叶产生同等强度,没有面孔翻转效应的P100电位;随后同时在两侧大脑颞枕部产生具有明显右侧大脑优势和面孔翻转效应的特异性N170;最后,在额中央区产生晚期对于面孔进行分析加工的N300成分。     

Impact of visual learning on facial expressions of physical distress: a study on voluntary and evoked expressions of pain in congenitally blind and sighted individuals

The ability to facially communicate physical distress (e.g. pain) can be essential to ensure help, support and clinical treatment for the individual experiencing physical distress. So far, it is not known to which degree this ability represents innate and biologically prepared programs or whether it requires visual learning. Here, we address this question by studying evoked and voluntary facial expressions of pain in congenitally blind (N = 21) and sighted (N = 42) individuals. The repertoire of evoked facial expressions was comparable in congenitally blind and sighted individuals; however, blind individuals were less capable of facially encoding different intensities of experimental pain. Moreover, blind individuals were less capable of voluntarily modulating their pain expression. We conclude that the repertoire of facial muscles being activated during pain is biologically prepared. However, visual learning is a prerequisite in order to encode different intensities of physical distress as well as for up- and down-regulation of one's facial expression.     

Conscious and nonconscious processes: An ERP index of an anticipatory response in a conditioning paradigm using visually masked stimuli

This study investigates the nonconscious elicitation of a previously conditioned response by using a differential conditioning paradigm with visually masked affectively valent facial schematics. Electrodermal (skin conductance response [SCR]) and brain (event-related potential [ERP]) activity were main dependent measures. Following a preconditioning phase in which subjects viewed energy masked pleasant and unpleasant facial schematics, conditioning with an aversive shock was established to unmasked presentations of an unpleasant face in a partial factorial design. A postconditioning phase of masked presentations, when compared with the preconditioning phase, revealed how the conditional effect within awareness might affect the same stimuli when presented outside awareness. An adaptive staircase technique was used to establish individual threshold levels, which represented a methodological advance over procedures typically used in visual masking research. The results revealed that responses to the CS+ (unpleasant face) changed significantly in predicted directions from preconditioning to postconditioning phase when compared with responses to the CS? (pleasant face). The SCR results systematically replicated recent Ohman, Dimberg, and Esteves (1988) findings, with the pattern of responses resembling a resistance to extinction effect. A new finding emerged for the brain responses. For the CS+, distinct slow wave activity occurred just before the point at which the shock had been delivered in the conditioning phase; no such activity was found for the CS?. This slow wave activity is similar to what has been described by others as an expectancy wave. The results indicate that an anticipatory process, as indexed by different physiological systems, can be elicited entirely outside awareness. Implications are discussed in regard to the nature of conscious and nonconscious processes.     

The impact of the stimulus features and task instructions on facial processing in social anxiety: An ERP investigation

Social anxiety has been characterized by an attentional bias towards threatening faces. Electrophysiological studies have demonstrated modulations of cognitive processing from 100 ms after stimulus presentation. However, the impact of the stimulus features and task instructions on facial processing remains unclear. Event-related potentials were recorded while high and low socially anxious individuals performed an adapted Stroop paradigm that included a colour-naming task with non-emotional stimuli, an emotion-naming task (the explicit task) and a colour-naming task (the implicit task) on happy, angry and neutral faces. Whereas the impact of task factors was examined by contrasting an explicit and an implicit emotional task, the effects of perceptual changes on facial processing were explored by including upright and inverted faces. The findings showed an enhanced P1 in social anxiety during the three tasks, without a moderating effect of the type of task or stimulus. These results suggest a global modulation of attentional processing in performance situations.     

Size and contrast have only small effects on the responses to faces of neurons in the cortex of the superior temporal sulcus of the monkey

Summary There is a population of neurons in the cortex in the middle and anterior part of the superior temporal sulcus (STS) of the monkey with responses which are selective for faces. To investigate whether the responses of these neurons show some of the perceptual properties of face recognition such as tolerance to changes in the size and contrast of the face, the effects of alteration of the size and contrast of an effective face stimulus on the responses of these neurons were analysed quantitatively in macaque monkeys. First, it was shown that the majority of these neurons had responses which were relatively invariant with respect to the size of the stimulus. The median size change tolerated with a response of greater than half the maximal response was 12 times. Second, it was found that for a few of these neurons, the size of the face did affect the neuronal response. For most of these neurons, it was found that when the size of the image and its distance were altered, the neuronal response was related to the retinal angle subtended by the image. But for four neurons the absolute size of the image determined the magnitude of the neuronal response, independently of the distance of the image. Thus these four neurons showed size constancy. It is suggested that these neurons would be useful as part of a face recognition system, because only objects in a certain absolute size range should normally be classified as faces. Third, the responses of the neurons were relatively invariant with respect to the contrast of the face. The mean contrast at which the neurons still responded with more than half the maximal response was 0.26. Fourth, the responses of the neurons were relatively invariant with respect to the sign of the contrast of the face, that is the neurons responded to negative as well as to positive images of faces. Fifth, the neurons typically responded to a face when the information in it had been reduced from 3D to a 2D representation in gray on a monitor, with a response which was on average 0.5 that to a real face. These results show that the responses of these neurons have some of the invariant properties with respect to size and contrast alteration shown by face perception, and show that their processing is at a level which would be useful in face recognition. The results also show that the responses of these neurons are not simply to local contour information.     

Cortisol-induced enhancement of emotional face processing in social phobia depends on symptom severity and motivational context

We investigated the effects of cortisol administration on approach and avoidance tendencies in 20 patients with social anxiety disorder (SAD). Event-related brain potentials (ERPs) were measured during a reaction time task, in which patients evaluated the emotional expression of photographs of happy and angry faces by making an approaching (flexion) or avoiding (extension) arm movement. Patients showed significant avoidance tendencies for angry but not for happy faces, both in the placebo and cortisol condition. Moreover, ERP analyses showed a significant interaction of condition by severity of social anxiety on early positive (P150) amplitudes during avoidance compared to approach, indicating that cortisol increases early processing of social stimuli (in particular angry faces) during avoidance. This result replicates previous findings from a non-clinical sample of high anxious individuals and demonstrates their relevance for clinical SAD. Apparently the cortisol-induced increase in processing of angry faces in SAD depends on symptom severity and motivational context.     

Studies of the effects of Vilon and Epithalon on gene expression in mouse heart using DNA-microarray technology

Expression of 15,247 clones from a cDNA library in the heart of mice receiving Vilon and Epithalon was studied by DNA-microarray technology. We revealed 300 clones (1.94% of the total count), whose expression changed more than by 2 times. Vilon changed expression of 36 clones, while Epithalon modulated expression of 98 clones. Combined treatment with Vilon and Epithalon changed expression of 144 clones. Vilon alone or in combination with Epithalon activated expression of 157 clones (maximally by 6.13 times) and inhibited expression of 23 clones (maximally by 2.79 times). Epithalon alone or in combination with Vilon activated expression of 194 clones (maximally by 6.61 times) and inhibited expression of 48 clones (maximally by 2.71 times). Our results demonstrate the specific effects of Epithalon and Vilon on gene expression.     

重组人IL-2在E.coli中的高效表达诱导因素及其纯化的研究

表达人IL-2的E.coli pETI-2/MM294在色氨酸饥饿的培养基中发酵,加入一定量的3—吲哚乙酸诱导其trp启动子,可以使rlL-2的表达量高达总菌体蛋白量的19％。高水平表达的rlL-2以不溶性的包含体形式存在于E.coli的胞浆中。通过破碎细菌、变性抽提和使rlL-2复性后,再经CM-SephadexC-50、DEAE-SephadexA-50、SephadexG-75等一系列层析步骤纯化,最终得到的rlL-2纯度达90％以上,比活性为7.21×10~5μ/mg,总回收率为10.5％。     

人白细胞介素2受体α链cDNA导入哺乳细胞及其克隆与稳定表达的研究

按DNA—磷酸钙共沉淀法将人白细胞介素2受体α链cDNA转染中国仓鼠卵巢细胞(CHOdhfr~-)及小鼠成纤维细胞(L929),获得稳定表达人IL-2Rα链的CHOdhfr~+细胞克隆。经RNA点渍杂交分析、荧光标记IL-2染色法、特异性ELISA和玫瑰花环试验检测证明,哺乳细胞表达的重组IL-2Rα链具有结合IL-2和抗Tac McAb的能力。还报道了T细胞白血病Jukat及Molt-4等细胞系异常表达IL-2R的结果,并作了分析讨论。