Attention and spatial selection: electrophysiological evidence for modulation by perceptual load

Behavioral data have suggested that perceptual load can modulate spatial selection by influencing the allocation of attentional resources at perceptual-level processing stages (Lavie & Tsal, 1994). To directly test this hypothesis, event-related potentials (ERPs) were recorded for both low- and high-perceptual-load targets in a probabilistic spatial cuing paradigm. The results from three experiments showed that, as measured by the lateral occipital P1 and N1 ERP components, the magnitude of spatially selective processing in extrastriate visual cortex increased with perceptual load. Furthermore, these effects on spatial selection were found in the P1 at lower levels of perceptual load than in the N1. The ERP data thus provide direct electrophysiological support for proposals that link perceptual load to early spatial selection in visual processing. However, our findings suggest a relatively broader model--where perceptual load is but one of many factors mediating early selection.     

网络成瘾者工作记忆水平受影响的机制:来自ERP的证据

本研究采用事件相关电位技术(ERP),以N-back范式为实验任务,考察20名网络成瘾大学生和23名对照组大学生的工作记忆水平,结果发现:对照组的工作记忆具有一定加工优势的趋势,正确率高于成瘾组,反应时低于成瘾组,但均未达到显著差异。网络成瘾组与对照组工作记忆加工时,网络成瘾组P2波幅更高,N2波幅更低,N2潜伏期更长,说明与网络成瘾组相比,对照组工作记忆水平更高。     

Detection and recognition: Concurrent processes in perception

In two experiments, event-related brain potentials (ERPs) were recorded while subjects performed a simultaneous detection and recognition task. Ten subjects listened to pure tones in noise and reported both whether a target tone had occurred (using a four-category confidence rating scale) and whether the target was one of two (Experiment 1) or four (Experiment 2) tones differing in frequency. The amplitudes of three ERP components were found to be differentially related to detection and recognition performance. The early N100 component varied with processing related only to detection, while the late P300 varied with both detection and recognition, and a later slow positive shift varied only with recognition and not with detection. While the latenciee of both N100 and P300 increased for less confident target detections, there were no differences in the latencies of these ERP components between correctly and incorrectly identiffed targets. Recognition performance was above the level expected by chance even when subjects reported that no target had been presented. The results indicate that brain potential components can be used to disclose temporal features of the processing of a stimulus by the nervous system and support the view that detection and recognition are partially independent, concurrent processes in perception.     

Young adults with severe congenital hypothyroidism: cognitive event related potentials (ERPs) and the significance of an early start of thyroxine treatment

Congenital hypothyroidism (CH) has devastating effects upon brain development if left untreated. Despite early start of thyroxine treatment, patients still show subtle cognitive deficits compared to controls. We aimed to study auditory event related potentials (ERPs) in young CH adults (N = 12) to verify previous reports of normal attention functions measured by P3 in CH children. We also include ERP components (P1, N1, P2) allowing assessment of a wider range of auditory processing functions. No significant change in P3 latency or amplitude was found in the CH group, but a more subtle change in amplitude topography. A later start of thyroxine treatment was related to increased P3 latency and reduced amplitude. Group differences were found in early ERP components tapping sensory processing, sensory gating and selective attention. The results suggest persisting abnormalities in auditory processing and selective attention that may have influenced cognitive development.     

儿童与成人对社会和非社会正性情绪刺激脑电反应特征比较

采用事件相关电位技术探究不同年龄群体社会与非社会正性情绪刺激加工是否具有差异。研究发现：在P2成分上,成人在情绪刺激下诱发的波幅大于儿童;N2成分上,儿童在三种情绪刺激条件下波幅无显著差异。成人在社会性情绪刺激条件下诱发的脑电波幅大于在中性情绪刺激条件和非社会情绪刺激条件下诱发波幅;在LPP早、中、晚时间窗中,儿童的LPP波幅大于成人。由此,儿童与成人在社会和非社会正性情绪刺激加工上存在明显差异。     

The neurophysiological correlates of face processing in adults and children with Asperger's syndrome

Past research has found evidence for face and emotional expression processing differences between individuals with Asperger's syndrome (AS) and neurotypical (NT) controls at both the neurological and behavioural levels. The aim of the present study was to examine the neurophysiological basis of emotional expression processing in children and adults with AS relative to age- and gender-matched NT controls. High-density event-related potentials were recorded during explicit processing of happy, sad, angry, scared, and neutral faces. Adults with AS were found to exhibit delayed P1 and N170 latencies and smaller N170 amplitudes in comparison to control subjects for all expressions. This may reflect impaired holistic and configural processing of faces in AS adults. However, these differences were not observed between AS and control children. This may result from incomplete development of the neuronal generators of these ERP components and/or early intervention.     

知觉组织影响时序知觉的认知机制:ERP研究的证据

以往研究显示,知觉组织影响时序知觉,采用ERP技术拟探讨知觉组织影响时序知觉的认知机制。采集23名被试完成同时判断任务的脑电数据。行为结果发现,知觉组织影响时序知觉,具体表现为知觉组织条件的同时判断频率显著高于非知觉组织条件。ERPs结果发现,在P1和P2成分上,知觉组织条件与非知觉组织条件引发的波幅没有显著差异; 而在N1成分上,知觉组织条件诱发的N1波幅显著大于非知觉组织条件。这表明,知觉组织对时序知觉的影响可能发生在视觉刺激加工的早期阶段,视觉刺激的知觉组织先于时序信息加工。     

Syntactic processing of Hebrew sentences in normal and dyslexic readers: electrophysiological evidence

The authors examined differences in brain activity as measured by amplitudes and latencies of event-related potential (ERP) components in Hebrew-speaking adult dyslexic and normal readers. The participants were measured while processing words' syntactic functions during reading of sentences with subject-verb-object syntactic order. The results suggested that among dyslexic and normal readers, N100 and P300 ERP components were sensitive to certain constituents of syntactic analysis for target words in accordance with their grammatical roles. The findings further demonstrated significant differences in ERP measures between dyslexic and normal readers. Compared with normal readers, dyslexic readers exhibited consistently higher amplitudes and longer latencies in both ERP components for the subject of the sentence. Significant, though less consistent, ERP variations were observed for other sentence elements. In addition, dyslexic readers differed from normal readers in their processing strategies. For normal readers, the verb-oriented, morphologically based strategy was found to be the most efficient for sentence processing in Hebrew, whereas the dyslexic readers demonstrated a more primitive mode of identification of words' grammatical roles, namely, the word-order strategy. The results support the hypothesis that there is a syntactic processing "weakness" in dyslexics.     

Continuous perception and graded categorization: electrophysiological evidence for a linear relationship between the acoustic signal and perceptual encoding of speech

Speech sounds are highly variable, yet listeners readily extract information from them and transform continuous acoustic signals into meaningful categories during language comprehension. A central question is whether perceptual encoding captures acoustic detail in a one-to-one fashion or whether it is affected by phonological categories. We addressed this question in an event-related potential (ERP) experiment in which listeners categorized spoken words that varied along a continuous acoustic dimension (voice-onset time, or VOT) in an auditory oddball task. We found that VOT effects were present through a late stage of perceptual processing (N1 component, ~100 ms poststimulus) and were independent of categorization. In addition, effects of within-category differences in VOT were present at a postperceptual categorization stage (P3 component, ~450 ms poststimulus). Thus, at perceptual levels, acoustic information is encoded continuously, independently of phonological information. Further, at phonological levels, fine-grained acoustic differences are preserved along with category information.     

Syntactic Processing of Hebrew Sentences in Normal and Dyslexic Readers: Electrophysiological Evidence

The authors examined differences in brain activity as measured by amplitudes and latencies of event-related potential (ERP) components in Hebrew-speaking adult dyslexic and normal readers. The participants were measured while processing words' syntactic functions during reading of sentences with subject-verb-object syntactic order. The results suggested that among dyslexic and normal readers, N100 and P300 ERP components were sensitive to certain constituents of syntactic analysis for target words in accordance with their grammatical roles. The findings further demonstrated significant differences in ERP measures between dyslexic and normal readers. Compared with normal readers, dyslexic readers exhibited consistently higher amplitudes and longer latencies in both ERP components for the subject of the sentence. Significant, though less consistent, ERP variations were observed for other sentence elements. In addition, dyslexic readers differed from normal readers in their processing strategies. For normal readers, the verb-oriented, morphologically based strategy was found to be the most efficient for sentence processing in Hebrew, whereas the dyslexic readers demonstrated a more primitive mode of identification of words' grammatical roles, namely, the word-order strategy. The results support the hypothesis that there is a syntactic processing “weakness” in dyslexics.     

Event-related brain potentials reveal differences in emotional processing in alexithymia

ABSTRACT

The inability to recognise and describe emotions in the self is known as Alexithymia. In the present study we used event-related potentials (ERPs) to examine the locus of processing emotional differences in alexithymia. We tested men, both those scoring high (score?>?61) and controls who scored low (score?<?51) on the Toronto Alexithymia Scale-20 on an emotional face discrimination task. We assessed three ERP components: P1 (an index of early perceptual processing), N170 (an index of early facial processing) and P3 (an index of late attentional suppression). While controls showed a stronger P3 effect for angry faces relative to happy and neutral faces, Alexithymic men showed no significant differences in P3 across emotions. Alexithymic men showed delayed P1 and N170 amplitudes compared to controls. These results suggest that the locus of processing differences between alexithymic men and controls occur both early in perceptual processing and later in conscious processing.     

On the locus of the semantic satiation effect: Evidence from event-related brain potentials

The present study sought to determine whether semantic satiation is merely a by-product of adaptation or satiation of upstream, nonsemantic perceptual processes or whether the effect can have a locus in semantic memory. This was done by measuring event-related brain potentials (ERPs) in a semantic word-detection task involving multiple presentations of primes and critical related and unrelated words in three experiments involving visual (Experiment 1) and auditory (Experiments 2A and 2B) stimuli. Primes varied in their type case (Experiment 1) or pitch (Experiment 2B) in order to discourage sensory adaptation. Prime satiation and relatedness of the primes to the critical word had interacting effects on ERP amplitude to critical words, particularly within the time-window of the N400 component. Because numerous studies have indicated a role for the N400 in semantic processing, modulation of the N400 relatedness effect by prime satiation (with little or no contribution from perceptual adaptation) suggests that semantic memory can be directly satiated, rather than the cost to semantic processing necessarily resulting from impoverishment of perceptual inputs.     

Selective attention to color and location: An analysis with event-related brain potentials

Event-related brain potentials (ERPs) were recorded from subjects as they attended to colored bars that were flashed in random order to the left or right of fixation. The task was to detect slightly smaller target bars having a specified color (red or blue) and location (left or right). The ERP elicited by stimuli at an attended location contained a sequence of phasic components (P122/N168/N264) that was highly distinct from the sequence associated with selection on the basis of color (N150-350/P199/P400-500). These findings suggested that spatially focused attention involves a gating or modulation of evoked neural activity in the visual pathways, whereas color selection is manifested by an endogenous ERP complex. When the stimulus locations were widely separated, the ERP signs of color selection were hierarchically dependent upon the prior selection for spatial location. In contrast, when the stimulus locations were adjacent to one another, the ERP signs of color selection predominated over those of location selection. These results are viewed as supporting “early selection” theories of attention that specify the rejection of irrelevant inputs prior to the completion of perceptual processing. The implications of ERP data for theories of multidimensional stimulus processing are considered.     

Deficits in early-stage face perception in excessive internet users

Excessive Internet use is associated with a limited ability to communicate effectively socially, which depends largely on the capacity for perception of the human face. We used a passive visual detection paradigm to compare the early stages of the processing of face-related information in young excessive Internet users (EIUs) and healthy normal subjects by analyzing event-related potentials (ERPs) elicited by faces and by nonface stimuli (tables), each presented in the upright and inverted position. The P1 and N170 components of the spectrum of ERPs elicited at occipital-temporal sites by the viewing of faces were larger and peaked sooner than the same ERP components elicited by tables, and inverted faces significantly enhanced and delayed the N170 component. EIUs had a generally smaller P1 component than did normal subjects, whether elicited by faces or by tables, and the N170 effect, or difference in amplitude of the N170 component for faces versus tables, was significantly smaller in the EIUs than in normal subjects. However, the N170 inversion effect, or difference in amplitude of the N170 component elicited by upright versus inverted faces, was similar in the EIUs and normal subjects. These data indicate that EIUs have deficits in the early stage of face-perception processing but may have intact holistic/configural processing of faces. Whether some deeper processes of face perception, such as face memory and face identification, are affected in EIUs needs to be investigated further with more specific procedures.     

An event-related brain potential investigation of PTSD and PTSD symptoms in abused children

We tested 186 children ranging in age from 6 years, 10 months to 13 years, 7 months; 174 suffered either physical and/or sexual abuse, and 12 were nonabused children. Abused subjects were grouped in four different ways. The primary grouping was based on whether subjects satisfied the DSM III-R criteria for posttraumatic stress disorder (PTSD). Secondary groupings were based upon the three symptom clusters used to make the PTSD diagnosis (arousal, avaidance, and reexperiencing). In each of these groupings three separate subgroups were formed with approximately 25 percent in the high and low symptom count subgroups and the remaining 50 percent in the middle symptom count subgroup. Subjects listened to four different intensity levels (65, 80, 95, and 102 dB) of a 1 KHz tone, pseudo-randomly ordered, while event-related brain potentials (ERPs) were recorded. Two separate blocks were used, one with short intervals (4±1 sec) between tones and the other with longer intervals (17±2 sec). PTSD subjects presented a greater P2-N2 ERP intensity gradient (i.e., a larger increase in the P2-N2 ERP component as tone intensity increased) than did abused subjects without PTSD. Abused subjects with the highest number of reexperiencing symptoms showed a similar P2-N2 augmenting effect when compared to those with the lowest number of reexperiencing symptoms. Subjects with the highest number of arousal symptoms showed a shallower intensity gradient for the N1-P2 ERP component than did those with fewer arousal symptoms. The results are discussed in relation to previous results reported on adults with PTSD and in terms of CNS processing of stimulus intensity information.     

正常老化对视觉早期注意的影响——来自ERP的证据

选择性注意能够作用于视觉信息加工的不同阶段。各个注意阶段均受到老化过程的影响, 其中注意早期阶段的老化研究对于理解认知老化的发生机制有重要意义。本文系统地梳理了刺激前的注意预期阶段以及刺激后200 ms内的早期感知注意阶段的正常老年人和青年人ERP比较研究, 以探讨正常老化对视觉早期注意的影响。现有证据表明, 相对于青年人, 正常老年人：(1)多个早期ERP注意效应(包括注意预期ADAN, 早期空间注意N1, 以及特征注意SP和SN)在潜伏期上都存在显著延迟; (2)在振幅上, 不同ERP注意效应的老化表现存在差异：某些ERP成分(包括注意预期EDAN, 以及早期空间注意P1)的注意效应没有明显减弱, 而某些ERP成分(包括注意预期alpha, 早期空间注意N1, 以及特征注意SN)的注意效应受到老化调控; (3)一些注意效应(包括特征注意SP成分, 以及客体注意P1和N1成分)的目标增强机制保留, 而干扰抑制机制缺损。目前已有研究在老化对注意效应振幅的调控上还存在不一致, 这可能与研究的信噪比、任务难度、注意机制分离以及老年人的个体差异有关。未来研究应考虑这些因素以更好地探究正常老化对视觉早期注意的影响。     

Event-related potentials and the semantic matching of pictures

Event-related potentials (ERPs) were recorded from one midline and three pairs of lateral electrodes while subjects determined whether pairs of sequentially presented pictures were semantically associated. The ERPs evoked by the second picture of each pair differed as a consequence of whether it was associated with its predecessor, such that ERPs to nonassociated pictures were more negative-going than those to associated items. These differences resulted from the modulation of two ERP components, one frontally distributed and centered on an N300 deflection, the other distributed more widely over the scalp and encompassing an N450 deflection. The modulation of N450 is interpreted as further evidence that the "N400" ERP component is sensitive to semantic relationships between nonverbal stimuli. The earlier N300 effects, which do not appear to occur when ERPs are evoked by semantically primed and unprimed words, could suggest that the semantic processing of pictorial stimuli involves neural systems different from those associated with the semantic processing of words.     

注意促进效应的ERP研究

近期发现,采用目标探测任务作为二级任务时,目标探测条件不仅不会削弱,甚至会提高记忆成绩,产生注意促进效应（ABE）。为进一步探究目标探测的作用机制,研究采用事件相关电位（ERP）技术,对比目标与分心条件在编码和提取过程中所诱发的ERP差异。结果表明,两类条件在再认过程中所诱发的ERP差异不仅表现在早期与知觉加工相关的ERP成份上,并且一直持续到了后期与细节提取相关的ERP成分上。由此推测,ABE不仅体现在编码早期的知觉加工阶段,更会延续到后期的复述与精加工。     

Perceptual organization and schizotypy.

The preattentive visual information processing of hypothetically psychosis-prone college subjects was evaluated using three different paradigms, target detection (n = 57), visual suffix effect (n = 57), and configural superiority effect (n = 68). It was hypothesized that anhedonic subjects would show the same perceptual organization deficits reported in process schizophrenics and that perceptual aberration-magical ideation subjects and depressed subjects would perform similarly to control subjects. In each study, anhedonics performed similarly to each comparison group, even though there was adequate power to detect performance differences if they existed. A framework for understanding the visual information-processing deficits of schizophrenics and high-risk subjects is proposed.     

知觉负载对负性分心面孔的知觉加工和记忆的影响

本研究采用视觉搜索和意外再认记忆任务,结合事件相关电位技术,考察知觉负载对负性分心面孔的知觉加工和记忆的影响。在视觉搜索任务中,行为上恐惧分心面孔在高负载下干扰任务。ERP结果上,恐惧比中性分心面孔诱发更大的N170和N250;在低负载下恐惧比中性分心面孔诱发更大的N700,在高负载下没有差异。在意外再认记忆中,个体对低负载下的恐惧分心面孔表现出记忆。这些结果说明负性分心物在早期是自动化加工;晚期加工受知觉负载的调节,负载越低对负性分心物的过滤越少,存在对负性分心物的记忆偏向。