Electrophysiology in neuropsychiatric research: a network perspective

A growing number of anatomic and physiologic studies have shown that parallel sensory and motor information processing occurs in multiple cortical areas. These findings challenge the traditional model of brain processing, which states that the brain is a collection of physically discrete processing modules that pass information to each other by neuronal impulses in a stepwise manner. New concepts based on neural network models suggest that the brain is a dynamically shifting collection of interpenetrating, distributed, and transient neural networks. Neither of these models is necessarily mutually exclusive, but each gives different perspectives on the brain that might be complementary. Each model has its own research methodology, with functional magnetic resonance imaging supporting notions of modular processing, and electrophysiology (eg, electroencephalography) emphasizing the network model. These two technologies might be combined fruitfully in the near future to provide us with a better understanding of the brain. However, this common enterprise can succeed only when the inherent limitations and advantages of both models and technologies are known. After a general introduction about electrophysiology as a research tool and its relation to the network model, several practical examples are given on the generation of pathophysiologic models and disease classification, intermediate phenotyping for genetic investigations, and pharmacodynamic modeling. Finally, proposals are made about how to integrate electrophysiology and neuroimaging methods.     

Psychophysiologic chronometry: detection of facilitating and inhibiting processes in information processing using electroencephalographic and electromyographic data]

The objective of the present research was to tally the potential usefulness of psychophysiological measures in the systematic analysis of human information processing. Different context conditions were established in two cued choice-reaction time experiments. The context could either facilitate or inhibit the processing of an imperative stimulus. Event-related brain potentials (EEG-ERP) and event-related electromyograms (EMG-ERP) were recorded and from these biosignals latencies and duration times for different aspects of stimulus evaluation and movement execution were derived. The EEG-ERP provided measures for the time of primary stimulus categorization (N2), the time necessary to test actual stimulus information against stimulus expectancies (P3b), and the time necessary to check the decision about the stimulus-response mapping (pSW). From the EMG-ERP, processing times were derived which are related to the initiation of a motor program and to distinct sections of the movement trajectory. Results show that these latency measures react differently to different context manipulations. EEG-ERP measures, for example, reflected differences during stimulus evaluation which were not detectable in response- or EMG-derived movement times. The parallel analysis of EEG-ERPs and EMG-ERPs allowed delineation of processing modules which are responsible for particular context-dependent facilitation and inhibition effects. Moreover, the data revealed substantial overlap of evaluation times and movement times. This finding seems to be more compatible with a parallel processing model than with a strictly sequential model.     

Information processing speed deficits may be better correlated with the extent of white matter sclerotic lesions in multiple sclerosis than previously suspected

Despite frequent use of the Paced Auditory Serial Addition Test (PASAT; Gronwall, 1977) for examining information processing speed (IPS) deficits in multiple sclerosis (MS), prior literature on the relationship between PASAT performance and severity of brain disease has been contradictory. In the present study, we found that PASAT performance is moderately well correlated with the total area of sclerotic brain lesions in MS patients only if a modified scoring method (mean "dyad" score; Snyder et al., 1993), but not the standard scoring method, is applied. We conclude that the PASAT remains a useful measure of IPS in MS, if a flaw in the typical scoring technique for this test is corrected. In our sample of 41 MS patients, for every one point decrease in mean dyad score, total lesion area increased by 364.08 mm2 on average, after controlling for age, sex, and education. IPS deficits are more severe for patients with greater brain disease, due to increased disruption of the white matter pathways that likely support the parallel distributed processing of complex information by geographically distant brain regions.     

人声加工的神经机制

人声是人类听觉环境中最熟知和重要的声音, 传递着大量社会相关信息。与视觉人脸加工类似, 大脑对人声也有着特异性加工。研究者使用电生理、脑成像等手段找到了对人声有特异性反应的脑区, 即颞叶人声加工区(TVA), 并发现非人类动物也有类似的特异性加工区域。人声加工主要涉及言语、情绪和身份信息的加工, 分别对应于三条既相互独立又相互作用的神经通路。研究者提出了双通路模型、多阶段模型和整合模型分别对人声的言语、情绪和身份加工进行解释。未来研究需要进一步讨论人声加工的特异性能否由特定声学特征的选择性加工来解释, 并深入探究特殊人群(如自闭症和精神分裂症患者)的人声加工的神经机制。     

局部表象产生中行为性别差异的神经基础

行为研究发现女性具有更好的局部表象产生能力, 但其神经基础尚不清楚。研究采用事件相关电位技术以及小世界网络分析方法, 探索局部表象产生中性别差异的大脑信息加工基础。结果显示在局部表象产生中, 女性行为反应较男性更快, 表象产生诱发的P300-650平均波幅更小, 且大脑功能网络的平均路径长度更短。深入分析发现, 反应时与脑网络的平均路径长度之间成正相关。该结果意味着低耗高效的大脑信息加工模式是女性具有更好的局部表象能力的神经基础。     

基于神经元群选择理论的脑信息处理模型研究

从认识论的角度,分析了国内外脑机能模型的研究概况。总结脑信息处理的三个特性:选择性、适应性及协同性,并论述了涵盖此三个特性的神经元群选择理论。基于神经元群选择理论,提出神经元群的三种类型,并据此建立脑信息处理的模型。     

Symbolic distance affects two processing loci in the number comparison task

A dual-task procedure was used to investigate the attentional requirements of number processing. The results show that (1) numeric information in Task 2 can be retrieved in parallel with capacity-demanding processing in Task 1 but (2) comparing two quantities requires central capacity, which is depleted by switching from one task to another. This finding resolves an apparent discrepancy in the literature, in which digit magnitude information has not been retrieved in parallel with a second task (Logan & Schulkind, 2000), despite repeated demonstrations that this information is retrieved autonomously, even when it is deleterious to performance (Henik & Tzelgov, 1982). A model is proposed to reconcile existing findings with the new ones revealed in the present investigation.     

The source of dual-task limitations: Serial or parallel processing of multiple response selections?

Although it is generally recognized that the concurrent performance of two tasks incurs costs, the sources of these dual-task costs remain controversial. The serial bottleneck model suggests that serial postponement of task performance in dual-task conditions results from a central stage of response selection that can only process one task at a time. Cognitive-control models, by contrast, propose that multiple response selections can proceed in parallel, but that serial processing of task performance is predominantly adopted because its processing efficiency is higher than that of parallel processing. In the present study, we empirically tested this proposition by examining whether parallel processing would occur when it was more efficient and financially rewarded. The results indicated that even when parallel processing was more efficient and was incentivized by financial reward, participants still failed to process tasks in parallel. We conclude that central information processing is limited by a serial bottleneck.     

Segregated processing of facial identity and emotion in the human brain: A pet study

Abstract

The brain is organized into segregated areas of relative functional autonomy and specialization. This basic principle of cerebral organization is well documented for cognitive functions that differ drastically from one another, but less so for functions that belong to the same domain, such as face processing. Yet several sources of evidence point to a functional and structural dissociation of various aspects of face processing, as suggested by (1) an analysis of the perceptual and cognitive demands made by the processing of diverse properties conveyed by facial configurations, (2) selective impairment of aspects of face processing in brain-damaged patients, and (3) different localizations of face cells responsive to properties conveyed by faces such as identity and emotion in the monkey's brain. This study used positron emission tomography (PET) and magnetic resonance imaging (MRI) to delineate better the neurofunctional organization of face processing in the human brain, by measuring cerebral blood flow while subjects performed tasks involving the recognition of faces or the recognition of emotions expressed by faces. The results showed segregated processing of facial identity and facial emotion, with the former being performed predominantly in the ventro-mesial region of the right hemisphere including the limbic system, whereas the latter was carried out predominantly in the latter part of the right hemisphere and the dorsal region of the limbic system. This structural organization allows the parallel processing of different information contained in physiognomies and underlies the high efficiency with which humans process faces.     

A strong test of the dual-mode hypothesis

One account of facial cognition, the dual-mode hypothesis, maintains that there are two sources of information in a human face, featural and configural, and that these sources are processed simultaneously and independently of one another. According to the hypothesis, the processing and identification of upright faces relies primarily on configural information, and this information is disrupted to such an extent upon inversion as to result in a reliance on featural information for identifying inverted faces (e.g., Searcy & Bartlett, 1996). When considered in terms of the general characteristics of human information processing, the foundational assumptions of the dual-mode hypothesis are as follows: Facial information processing is accomplished by a parallel self-terminating architecture with unlimited capacity to supercapacity and a preservation of independence between the rates of processing of featural and configural information. Although a number of studies have provided evidence consistent with the dual-mode hypothesis, until now there have been no direct tests of the foundational assumptions of the hypothesis. The present study provides that direct test, providing strong support for three of the assumptions (parallel self-terminating processing with unlimited capacity to supercapacity) while contradicting a fourth (independence in rates).     

The Lower Visual Search Efficiency For Conjunctions Is Due To Noise and Not Serial Attentional Processing

Models of human visual processing start with an initial stage with parallel independent processing of different physical attributes or features (e.g. color, orientation, motion). A second stage in these models is a temporally serial mechanism (visual attention) that combines or binds information across feature dimensions. Evidence for this serial mechanism is based on experimental results for visual search. I conducted a study of visual search accuracy that carefully controlled for low-level effects: physical similarity of target and distractor, element eccentricity, and eye movements. The larger set-size effects in visual search accuracy for briefly flashed conjunction displays, compared with feature displays, are quantitatively predicted by a simple model in which each feature dimension is processed independently with inherent neural noise and information is combined linearly across feature dimensions. The data are not predicted by a temporally serial mechanism or by a hybrid model with temporally serial and noisy processing. The results do not support the idea that a temporally serial mechanism, visual attention, binds information across feature dimensions and show that the conjunction-feature dichotomy is due to the noisy independent processing of features in the human visual system.     

Race-Based Parsing and Syntactic Disambiguation

We present a processing model that integrates same important psychological claims about the human sentence-parsing mechanism: namely, that processing is influenced by limitations an working memory and by various syntactic preferences. The model uses time-constraint information to resolve conflicting preferences in a psychologically plausible way. The starting paint far this proposal is the Sausage Machine model (Fodor & Frazier, 1980: Frazier & Fodor, 1978). From there, we attempt to overcome the original model's dependence an ad hoc aspects of its grammar, and its omission of verb-frame preferences. We also add mechanisms far lexical disambiguation and semantic processing in parallel with syntactic processing.     

从个体关系的角度看文化对社会脑功能的塑造

摘 要 尽管社会认知的内容丰富多样,但其核心在于人们对“自我”、“他人”及两者关系的理解。文化作为一种独特的社会现象,对社会认知有着广泛影响,这一点集中体现在文化对“自我” 与“他人” 信息加工及其大脑机制的影响上。文化神经科学的研究表明：文化显著影响自我相关记忆、自我表征、自我觉知等自我认知过程。这可能主要来源于不同文化人群自我建构方式的不同。上述差异的神经机制主要体现为不同文化人群自我相关加工时,其内侧前额叶功能性变化的不同。与此相对应的是,文化同样显著影响人们对他人,尤其是对他人情绪的认知。这一点集中表现为表情认知的文化优势效应及共情过程的文化差异。在神经机制上这一差异主要体现为杏仁核功能的文化可塑性。文化神经科学的未来研究,可继续探讨主流文化、区域文化、宗教文化等各种形式的文化差异：1）对自我认知与情绪认知相互作用的影响与神经基础;2）对共情（empathy）、社会比较（social comparison）、心理理论（theory of mind）与协同行为（joint action）等多种社会认知过程的影响及其神经机制。 关键词 自我建构 文化神经科学 情绪认知 自我表征 共情     

Parallel processing of auditory and phonetic information in speech discrimination

Recent experiments using a variety of techniques have suggested that speech perception involves separate auditory and phonetic levels of processing. Two models of auditory and phonetic processing appear to be consistent with existing data: (a) a strictserial model in which auditory information would be processed at one level, followed by the processing of phonetic information at a subsequent level; and (b) aparallel model in which auditory and phonetic processing could proceed simultaneously. The present experiment attempted to distinguish empirically between these two models. Ss identified either an auditory dimension (fundamental frequency) or a phonetic dimension (place of articulation of the consonant) of synthetic consonant-vowel syllables. When the two dimensions varied in a completely correlated manner, reaction times were significantly shorter than when either dimension varied alone. This “redundancy gain” could not be attributed to speed-accuracy trades, selective serial processing, or differential transfer between conditions. These results allow rejection of a completely serial model, suggesting instead that at least some portion of auditory and phonetic processing can occur in parallel.     

不同强迫倾向个体信息加工方式的特点研究

采用Flanker范式,通过考察高低强迫倾向个体在Flanker任务上的差异,来研究强迫倾向个体信息加工方式的特点。研究结果显示,在Flanker任务中,高强迫倾向个体显示出较慢的反应速度,表现为更多的犹豫不觉的特性;高强迫倾向个体的信息加工方式以集中加工为主;高强迫倾向个体在信息加工的灵活性上存在不足,对情景的变化较不敏感。通过对强迫倾向个体的信息加工方式的研究,有助于丰富和发展强迫症的理论,同时为强迫症的临床治疗提供依据。     

Toward a translational model of Stroop interference

Models of the Stroop effect that postulate single, centralized processing stations are fundamentally incorrect. A translational model is proposed in which parallel processing systems are hypothesized that are linked by a translation mechanism. Each system processes information using its own internal code specifically linked to the type of information the system processes. Information is passed between these systems via the translation mechanism. Evidence supporting this model comes from both the literature and the experiments reported in this article. Of primary importance is the demonstration that the pattern of interference that emerges is dependent upon the cognitive system used to process the information.

     

A comparison of lexical-semantic impairments in left hemisphere stroke and Alzheimer's disease

Patients with aphasia due to left hemisphere stroke and patients with Alzheimer's disease, who were matched for severity of naming impairment, were compared on tests of lexical-semantic processing. The results suggest that the lexical-semantic impairments in both groups are due to a combination of impaired access to, and loss of, lexical-semantic information, but that impaired access is more prominent in stroke patients, whereas Alzheimer's disease patients suffer a greater loss of information. The results are discussed in terms of a brain model of the storage and processing of lexical-semantic information, and with respect to implications for treatment strategies.     

The shape of ears to come: dynamic coding of auditory space

In order to pinpoint the location of a sound source, we make use of a variety of spatial cues that arise from the direction-dependent manner in which sounds interact with the head, torso and external ears. Accurate sound localization relies on the neural discrimination of tiny differences in the values of these cues and requires that the brain circuits involved be calibrated to the cues experienced by each individual. There is growing evidence that the capacity for recalibrating auditory localization continues well into adult life. Many details of how the brain represents auditory space and of how those representations are shaped by learning and experience remain elusive. However, it is becoming increasingly clear that the task of processing auditory spatial information is distributed over different regions of the brain, some working hierarchically, others independently and in parallel, and each apparently using different strategies for encoding sound source location.     

Multiple Cues in Social Perception: The Time Course of Processing Race and Facial Expression

The purpose of the present study was to examine the time course of race and expression processing to determine how these cues influence early perceptual as well as explicit categorization judgments. Despite their importance in social perception, little research has examined how social category information and emotional expression are processed over time. Moreover, although models of face processing suggest that the two cues should be processed independently, this has rarely been directly examined. Event-related brain potentials were recorded as participants made race and emotion categorization judgments of Black and White men posing either happy, angry, or neutral expressions. Our findings support that processing of race and emotion cues occur independently and in parallel, relatively early in processing.