Event-related brain potentials and subjective probability in a learning task

In a paired associate learning task, subjects responded to each presentation of a nonsense syllable by typing both a three-letter associate and a rating of their confidence that this response was correct or incorrect. Average event-related potentials (ERPs) elicited by the subsequent presentation of the actual paired syllable varied with the interaction of confidence and trial outcome. A larger amplitude P300 was elicited by syllables that informed subjects that they were correct when they thought they were incorrect or that they were incorrect when they thought they were correct than by syllables that confirmed subjects expectations. That this average ERP result was indeed an effect on P300 amplitude, and not an artifact of single-trial variability in P30O latency, was confirmed with a trial-by-trial latency adjustment procedure. Consistent with findings from other tasks, P300 amplitude varied inversely with the subj ective probability of the ERP-eliciting events.     

Memory with and without awareness: performance and electrophysiological evidence of savings.

Event-related potentials (ERPs) recorded on the scalp were shown to be sensitive indicators of the strength of a memory trace on both implicit and explicit tests of memory. In explicit recognition tests, the amplitude of a positive potential identified as P300 was larger for "old" than for "new" words regardless of whether the subject categorized the items correctly. This effect, however, was statistically reliable only when the recognition memory (d') was relatively high. In contrast to ERPs, the reaction times in explicit recognition were sensitive to accuracy but not to repetition. In implicit tests, lexical decisions to repeated words were faster than to newly presented words. The magnitude of the repetition effect varied neither with elapsed time since the last repetition nor with the number of previous repetitions. In contrast, the P300 elicited by the same words were sensitive to both lag and recency of repetition, suggesting that they were influenced by the episodic memory strength of the items.     

Frontal deficits in alcoholism: an ERP study

Alcoholism is a major health problem afflicting people all over the world. Understanding the neural substrates of this addictive disorder may provide the basis for effective interventions. So-called "executive processes" play a role in cognitive functions like attention and working memory, and appear to be disrupted in alcoholism (Noel et al., 2001). Event related potentials (ERPs) provide an excellent, minimally invasive technique for exploring these neural deficits. The current study used the P300 in number sequencing task (modified version of the Petries & Milner, 1982) requiring working memory to compare a group of patients with alcoholism and frontal lobe lesions to patients with subcortical lesions and normal controls to assess the relationship of alcoholism to frontal lobe damage. The ERP paradigm was a Number Sequencing task. Electrophysiological results indicate that the frontal lesion group had significant P300 amplitude reduction and a similar trend for alcohol dependent group but not the subcortical group compared to the normal controls.     

Reconsolidation of declarative memory in humans

The reconsolidation hypothesis states that a consolidated memory could again become unstable and susceptible to facilitation or impairment for a discrete period of time after a reminder presentation. The phenomenon has been demonstrated in very diverse species and types of memory, including the human procedural memory of a motor skill task but not the human declarative one. Here we provide evidence for both consolidation and reconsolidation in a paired-associate learning (i.e., learning an association between a cue syllable and the respective response syllable). Subjects were given two training sessions with a 24-h interval on distinct verbal material, and afterward, they received at testing two successive retrievals corresponding to the first and second learning, respectively. Two main results are noted. First, the first acquired memory was impaired when a reminder was presented 5 min before the second training (reconsolidation), and also when the second training was given 5 min instead of 24 h after the first one (consolidation). Second, the first retrieval proved to influence negatively on the later one (the retrieval-induced forgetting [RIF] effect), and we used the absence of this RIF effect as a very indicator of the target memory impairment. We consider the demonstration of reconsolidation in human declarative memory as backing the universality of this phenomenon and having potential clinical relevance. On the other hand, we discuss the possibility of using the human declarative memory as a model to address several key topics of the reconsolidation hypothesis.     

认知事件相关电位P300与儿童青少年工作记忆的发展

研究采用ERP技术对59名儿童工作记忆水平与事件相关电位进行比较分析,以说明工作记忆发展的神经电生理基础及年龄特征。实验仪器为美国NICOLET公司生产的COMPACT FOUR脑诱发电位仪。结果发现:(1)儿童工作记忆水平与P300各成分潜伏期呈负相关,与P300各成分的振幅呈正相关。(2)儿童P300的各潜伏期随年龄增长而下降,振幅随年龄增长而增大。(3)不同性别儿童P300各成分均无显著性差异。     

Neural correlates of adaptation to voice identity

Apart from speech content, the human voice also carries paralinguistic information about speaker identity. Voice identification and its neural correlates have received little scientific attention up to now. Here we use event-related potentials (ERPs) in an adaptation paradigm, in order to investigate the neural representation and the time course of vocal identity processing. Participants adapted to repeated utterances of vowel-consonant-vowel (VCV) of one personally familiar speaker (either A or B), before classifying a subsequent test voice varying on an identity continuum between these two speakers. Following adaptation to speaker A, test voices were more likely perceived as speaker B and vice versa, and these contrastive voice identity aftereffects (VIAEs) were much more pronounced when the same syllable, rather than a different syllable, was used as adaptor. Adaptation induced amplitude reductions of the frontocentral N1-P2 complex and a prominent reduction of the parietal P3 component, for test voices preceded by identity-corresponding adaptors. Importantly, only the P3 modulation remained clear for across-syllable combinations of adaptor and test stimuli. Our results suggest that voice identity is contrastively processed by specialized neurons in auditory cortex within ～250 ms after stimulus onset, with identity processing becoming less dependent on speech content after ～300 ms.     

Disorder in sequential speech perception: a case study on pure word deafness

We described disorders of a patient which were uniquely restricted to speech perception of syllable sequences after brain damage. The results of series of experiments using syllable sequences showed "negative recency effect," in which the subject's repetition performance at the latter syllable position was remarkably poor. Experimental analyses suggested that the "negative recency effect" could be due to dual factors: the lower rate of processing of speech sounds and the memory load of holding processes of preceding syllables imposed on the succeeding phonological processing. The results also suggested that the holding processes which imposed the memory load on the succeeding auditory phonological coding processing were modality nonspecific.     

P300 and probability in children

The P300 event-related brain potential (ERP) was elicited in three groups of 12 children each, ages 5-9, 10-14, and 15-19 years. A simple auditory task was employed in which subjects indicated with a finger movement when a randomly occurring target tone (high pitch) was presented in a series of standard (low pitch) tones. The probability of the target tone was varied across conditions at 0.10, 0.30, or 0.50 to determine if P300 amplitude would respond similarly across age groups. Immediate memory capacity was measured with forward and reverse digit spans. P300 amplitude increased with decreases in target stimulus probability for each age group and also tended to become larger with age. P300 latency decreased in the same fashion across probability levels as age increased. Digit span demonstrated the usual increase with age. The results suggest that cognitive development is indexed by decreases in P300 latency, and that P300 amplitude changes from the probability of the target stimulus are similar across age groups. The implications for the theoretical interpretation of the P300 and application of ERPs for evaluating cognitive development are discussed.     

Does P3 Reflect Attentional or Memory Performances,or Cognition more Generally?

The study evaluated the off-line relationship of attention, memory and other cognitive performances with the auditory event-related potentials P3 (P300) and N2. The sample comprised 200 middle-aged construction workers. Verbal, visuomotor and memory tests were administered. Attentional domains were examined using CogniSpeed software. Slowed reaction times in the test of sustained attention (vigilance) were associated with delayed P3 latency (p < 0.001) and decreased P3 amplitude (p = 0.005), as well as with delayed N2 latency (p < 0.001). Visuomotor slowing in Digit Symbol was also related to delayed P3 latency (p = 0.030) and decreased P3 amplitude (p = 0.014). In contrast, mild cognitive impairment, short- and long-term memory, and concentrating or sharing attention with high working memory demands were not related to P3. The results suggest that P3 is linked to attentional performance with low working memory demands rather than to effortful working memory updating, retrieval from memory stores, or mild cognitive impairment.     

P300 stimulus sequence effects in children and adults

Immediate memory capability for 12 children (8 years) and 12 adults (21 years) was assessed electrophysiologically by using P300 event-related brain potential (ERP) stimulus sequences. These were derived from an auditory discrimination paradigm in which participants detected target stimuli in a series of target (T) and standard (S) tones that were varied by randomly presenting one of four sequence patterns (SSSS, TTTT, TTTS, SSST). Short-term memory capability was assessed behaviorally by recall performance of a 20-word list. Children and adults showed virtually identical P300 amplitude sequence patterns, such that for both groups component size increased systematically as the discrepancy between standard and target stimuli increased across sequence patterns. P300 latency evinced similar, albeit weaker, stimulus sequence effects, with children having longer component peak latencies. Memory recall performance was substantially weaker for the children than for adult participants, especially for recency effects. The findings suggest that immediate memory for stimulus sequences is fully developed in young children, although long-term memory is not.     

All parts of an item are not equal: Effects of phonological redundancy on immediate recall

The process of redintegration is thought to use top-down knowledge to repair partly damaged memory traces. We explored redintegration in the immediate recall of lists from a limited pool of partly phonologically redundant pseudowords. In Experiment 1, four kinds of stimuli were created by adding the syllable /ne/ to two-syllable pseudowords, either to the middle (/tepa/ vs. /tenepa/) or to the end (/tepane/), or adding a different syllable to each item (/tepalo/, /vuropi/). The repeated syllable was thought to be available for redintegration. Lists of two-syllable pseudowords were recalled best, items with a redundant end were intermediate, and items with a redundant middle-syllable were as hard as nonredundant three-syllable items. In Experiment 2, the last syllable was predictable from context but not shared between all stimuli, reducing phonological similarity between items. Performance did not differ from the situation with identicallast syllables. In Experiment 3, a shared first syllable had a detrimental effecton memory. An error analysis showed that beneficial redundancy effects were accompanied by harmful similarity effects, impairing memory for nonredundant syllables. The balance between the two effects depended on syllable position.     

Differential effects of voluntary expectancies on reaction times and event-related potentials: evidence for automatic and controlled expectancies.

Expectancy has been used to explain the effects of stimulus sequences both on reaction times (RTs) and on the P300 component of the human event-related potential. However, there are conflicting views about the control obtainable over these underlying expectancies. We compared the effects of voluntary expectancies for stimulus changes or repetitions in random tone series on RTs and the P300. Ss responded according to either stimulus identity (Experiment 1) or stimulus sequence (Experiment 2). In both experiments RTs were strongly affected by event expectedness. P300 amplitude, on the other hand, was affected (as a trend) only in Experiment 2. The results suggest that there are at least 2 types of "expectancy", one that is largely automatic and inflexible, reflected in P300 amplitude, and a second, controlled process that is reflected mainly in RT. The latter type of expectancy appears to affect processing stages beyond stimulus evaluation and classification.     

Mutual Interactions Between Speech and Finger Movements

Speech output and finger movements were recorded as right-handed males repeated a syllable while making cyclical finger movements in three experimental conditions: (a) maintaining constant amplitude in both response systems; (b) alternating speech amplitude while attempting to maintain constant finger movement amplitude; and (c) alternating finger movement amplitude while attempting to maintain constant speech amplitude. Observations showed that output of the two response systems was coupled (one syllable was uttered with each finger movement) and entrained in amplitude (the amplitude pattern of the response that the subject attempted to keep constant followed that of the concurrently-active amplitude-modulated response).

These interactions were bidirectional and were present with both left-handed and right-handed finger movements. The interactions are more extensive and subtle than mere interference with one response system by the other, and apparently do not depend on anatomical overlap of the responding neural systems.     

语言熟练度对Stroop效应的影响——不平衡双语者的任务态fMRI研究

目的:探讨语言熟练度对Stroop效应的影响及其背后的脑机制。材料与方法:17位被试参与本研究。被试母语为汉语,第二语言为英语。在被试完成中英文的stroop色字的任务过程中对被试进行fMRI扫描。结果:在色字相一致的条件下,中文任务与英文任务相比,双侧背侧枕叶及右侧背外侧前额叶有更强的激活; 反向比较,双侧腹侧枕叶有更强的激活。在色字不一致的条件下,中文任务与英文任务相比,双侧背外侧前额叶、右侧枕下回有更强的激活; 反向比较,并无显著激活的脑区。此外,中文Stroop效应引起左侧额下回显著的激活。英文Stroop效应中,左侧额下回无显著激活。结论:结合前人研究,我们得出,语言熟练度影响了对注意控制有重要作用的背外侧前额叶以及与反应抑制有关的左侧额下回在Stroop任务中的参与程度,进而影响了Stroop任务的表现     

Mutual interactions between speech and finger movements

Speech output and finger movements were recorded as right-handed males repeated a syllable while making cyclical finger movements in three experimental conditions: (2) maintaining constant amplitude in both response systems; (b) alternating speech amplitude while attempting to maintain constant finger movement amplitude; and (c) alternating finger movement amplitude while attempting to maintain constant speech amplitude. Observations showed that output of the two response systems was coupled (one syllable was uttered with each finger movement) and entrained in amplitude (the amplitude pattern of the response that the subject attempted to keep constant followed that of the concurrently-active amplitude-modulated response). These interactions were bidirectional and were present with both left-handed and right-handed finger movements. The interactions are more extensive and subtle than mere interference wtih one response system by the other, and apparently do not depend on anatomical overlap of the responding neural systems.     

“P300” and memory: Individual differences in the von Restorff effect

Event-related brain potentials (ERPs) were elicited by words in a free recall paradigm that included a novel item. The P300 component of the ERP is elicited by novel, task-relevant events, and we tested the hypothesis that P300 is a manifestation of the cognitive processing invoked during “context updating.” If the degree to which current representations in working memory need revision is related to P300 amplitude, then the P300 elicited by a given item should be related to the ability to recall that item on a subsequent test. Forty lists were presented to 12 subjects in each of two sessions. The lists were 15 words long, and 1 word, in position 6 through 10, was “isolated” by changing its size. Most subjects recalled these isolated words more often than other words in the same positions (von Restorff effect), and these words also elicited larger P300s than other words. Analysis of variance on the component scores from a principal components analysis revealed that words recalled had a larger amplitude P300 (on initial presentation) than words not recalled. Striking individual differences emerged, and there were strong relationships between the von Restorff effect, overall recall performance, mnemonic strategies, and the association between components of the ERP and recall performance. The overall recall performance of subjects who reported simple (rote) mnemonic strategies was low, but they showed a high von Restorff effect. For these subjects the amplitude of the P300 elicited by words during initial presentation predicted later recall. In contrast, subjects who reported complex mnemonic strategies remembered a high percentage of words and did not show a von Restorff effect. For these subjects P300 did not predict later recall, although a later “slow wave” component of the ERP did. The initial response to isolated items was the same for all subjects (a large P300), and all subjects recognized the isolates faster than other words in a recognition test given at the end of each session. The subjects in whom P300 did not predict recall reported mnemonic strategies that involved organizing the material. These strategies continue long after the time period reflected by P300 (600 msec). Because they were so effective they may have overshadowed the relationship between P300 and recall, which is based on the initial encoding of an event. Our interpretations were further confirmed and clarified from data obtained in a final grand recall and in the recognition test.     

中学生与大学生地震亲历者对威胁性刺激记忆偏向的比较研究

运用事件相关电位(ERPs)技术,采用学习-再认实验任务,考察了不同年龄阶段的地震亲历者(13个大学生、13个中学生)对威胁性刺激(地震相关图片)再认时记忆偏向的差异。结果表明:(1)在额叶-中央区,中学生经历组在旧的地震图片上P300成分的潜伏期显著短于大学生经历组;在顶叶-枕叶,中学生经历组在旧的地震图片上的P300峰值和LPC波幅显著大于大学生经历组。(2)对于经历组,地震图片均比中性图片对经历组诱发了更大的P300和LPC波幅。表明地震图片对中学生经历组的效应比对大学生经历组更大,地震经历组对地震相关图片有记忆偏向。     

Factors modulating the effect of divided attention during retrieval of words

In this study, we examined variables modulating interference effects on episodic memory under divided attention conditions during retrieval for a list of unrelated words. In Experiment 1, we found that distracting tasks that required animacy or syllable decisions to visually presented words, without a memory load, produced large interference on free recall performance. In Experiment 2, a distracting task requiring phonemic decisions about nonsense words produced a far larger interference effect than one that required semantic decisions about pictures. In Experiment 3, we replicated the effect of the nonsense-word distracting task on memory and showed that an equally resource-demanding picture-based task produced significant interference with memory retrieval, although the effect was smaller in magnitude. Taken together, the results suggest that free recall is disrupted by competition for phonological or word-form representations during retrieval and, to a lesser extent, by competition for semantic representations.     

P300和CNV在GKT的延时反应范式中测谎效果的分离

在杀人游戏情境中,设置无反馈和有反馈两个实验组,采用GKT（guilt knowledge test）的延时反应范式,考察P300和CNV两种ERP成分的测谎效果。结果发现：刺激呈现后大约450ms诱发了一个正性ERP成分（P300）,大约800ms诱发了一个负性ERP成分（CNV）。在有、无反馈两种实验范式下,P300和CNV两种测谎指标的变化情况发生了分离——有无反馈不影响P300峰值大小;而在有反馈条件下,“杀手”对于犯罪细节词语（探测刺激）的CNV明显增大。使用Bootstrap波幅差异分析法,分别计算P300和CNV在有、无反馈情况下的检出率,结果发现：两个指标的检出率在有、无反馈两种实验范式下的变化情况也发生了分离。这些结果表明：P300和CNV两个指标具有不同的测谎功能,这可能和它们所反映的不同欺骗心理过程有关。     

语文学习困难儿童汉字记忆编码的神经机制研究

采用事件相关电位方法,探讨语文学习困难儿童汉字记忆编码过程的特点.研究发现:语文学习困难组和对照组在编码过程的300-700ms均存在显著的相继记忆效应.语文学习困难组与对照组的Dm效应存在着显著的时间与空间上的差异.在Dm效应出现前,语文学习困难组加工的P2潜伏期显著晚于对照组.同时还发现,不同能力组加工的N2和LPC差异与Dm效应十分相似,对照组比语文学习困难组更正,与Dm效应不同,不同能力组加工的分离明显大于Dm效应的分离,且持续时间更长,一直持续到1000ms之后,远远晚于Dm效应的分离时间,对照组比语文学习困难组有一个更正的晚正成分.语文学习困难组与对照组在加工程度上存在差异,使编码项目的记忆痕迹呈现出不同特点.