Brain potential correlates of the “internal features advantage” in face recognition

Whereas some behavioral studies have shown that internal features are crucial for efficient face recognition in healthy adults, compared to external features, the brain mechanisms underlying this “internal features advantage” are still unknown. In the present study, the differential relevance of both subsets of facial features is addressed analyzing N400-like potentials elicited in a face-feature matching task, where external or internal features and complete face targets were displayed consecutively in each trial. Experiment 1 revealed a larger and longer-lasting N400-like effect with the prior presentation of internal features, which suggests more efficient processing of long-term face-related information. An analysis of neural sources in Experiment 2 revealed greater activation of frontal and left temporal brain areas in the processing of mismatching targets when preceded by internal features. Thus, brain electrical correlates of the “internal features advantage” could be verified around 300-400 ms post-stimulus and supported by a face-identity related neural network.     

Voltage-Based Versus Factor Score-Based Source Localization Analyses of Electrophysiological Brain Activity: A Comparison

Summary Though, traditionally, electrophysiological recordings have been limited to provide temporal information on neural activity, the development of mathematical algorithms capable of solving the inverse problem is facilitating, in recent years, the access to spatial information (i.e., on the origin of neural activation). This study explored a new strategy in order to increase the reliability of inverse problem solutions: applying these algorithms on factor scores (and not on voltages), a parameter that can be defined as clean amplitude. Factor scores derive from Principal Component Analysis (PCA) applied to event-related potentials (ERPs). The main advantage of PCA is its capability to extract and quantify ERP components free of the influence of adjacent or subjacent components. The LORETA algorithm for source localization was applied on peak voltage, average voltage and factor scores for the motor potential recorded from 25 subjects, who had to repeatedly press a button with their right hand. The solutions given by LORETA in these three modalities were compared. The motor potential, a negative wave that begins just before any voluntary movement and is centrally distributed in the scalp, is particularly useful to the scope of this study, since its origin is known: contralateral motor cortex. Results show that the three modalities (peak voltage, mean voltage and factor scores) provided the same main focus (left motor cortex), though the cleanest solution (i.e., the main focus was more salient with respect to other secondary, noisy foci) was achieved by the factor scorebased LORETA.     

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.     

Age-related changes in processing faces from detection to identification: ERP evidence

We examined the ability of people 70 to 90 years old to apply global, configural, and featural face-processing strategies. In addition we investigated age-related changes in the ability to categorize faces at basic, subordinate, and individual levels. Using the N170 potential as index of early face processing and the P300 component as index of categorical decision making and effort, we found significant age-related perceptual changes which slowed and somewhat impaired face processing. Specifically, older participants had problems integrating face features into global structures, demonstrating enhanced dependence on distal global information. They did not apply configural computations by default while processing faces which suggests that, unless identification is required, they process faces only at a basic level. These perceptual changes could be the cause for slower and less accurate subordinate categorization, particularly when it is based on details. At the neural levels face processing was not right-lateralized, reflecting excessive involvement of the left hemisphere in perception leading to a more general reduction of interhemispheric asymmetry. In addition we found excessive but nonselective activation of frontal regions adding support to the view that executive control and particularly inhibition of irrelevant input are reduced in the elderly.     

Right N170 modulation in a face discrimination task: an account for categorical perception of familiar faces

Behavioral studies have shown that two different morphed faces belonging to the same identity are harder to discriminate than two faces stemming from two different identities. The temporal course of this categorical perception effect has been explored through event-related potentials. Three kinds of pairs were presented in a matching task: (1) two different morphed faces representing the same identity (within), (2) two other faces representing two different identities (between), and (3) two identical morphed faces (same). Following the second face onset in the pair, the amplitude of the right occipitotemporal negativity (N170) was reduced for within and same pairs as compared with between pairs, suggesting an identity priming effect. We also observed a modulation of the P3b wave, as the amplitude of the responses for within pairs was higher than for between and same pairs, suggesting a higher complexity of the task for within pairs. These results indicate that categorical perception of human faces has a perceptual origin in the right occipitotemporal hemisphere.     

The category‐sensitive and orientation‐sensitive N170 adaptation in faces revealed by comparison with Chinese characters

By comparing faces with Chinese characters, the category‐sensitive and orientation‐sensitive N170 adaptation effects were examined when the stimuli were adapted by category (within vs. between) and orientation (same vs. different). The category‐sensitive N170 adaptation was present for both faces and characters, supporting the assertion that the perception of faces and characters recruits domain‐specific processing rather than general processing of visual expertise. In addition, the orientation‐sensitive N170 adaptation was present only for faces but not for characters, suggesting that only faces recruit orientation‐specific processing. More importantly, the orientation‐sensitive N170 adaptation was not only present for inverted faces but also for upright faces, indicating that there are distinct neuron populations respectively sensitive to upright and inverted faces.     

Early N400 development and later language acquisition

Recent developmental research on word processing has shown that mechanisms of lexical priming are already present in 12-month-olds whereas mechanisms of semantic integration indexed by the N400 mature a few months later. In a longitudinal setting we investigated whether the occurrence of an N400 at 19 months is associated with the children's language skills later on. To this end children were retrospectively grouped according to their verbal performance in a language test at 30 months. Children with later age-adequate expressive language skills already displayed an N400 at 19 months. In contrast, children with later poor expressive language skills who have an enhanced risk for the development of specific language impairment (SLI) did not show an early N400. The results imply that children who have deficits in their expressive language at the age of 30 months are already impaired in their semantic development about one year earlier.     

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。     

Underlying mechanisms of the P3a task-difficulty effect

In three-stimulus oddball studies, even typical deviant stimuli elicited a large P3a event-related brain potential (ERP) when target/standard discrimination was difficult. To investigate the underlying mechanisms, the effects of task difficulty on early deviant-related ERPs were assessed. Four visual stimuli defined by an orthogonal combination of task-relevant size (nontarget 80%, target 20%) and task-irrelevant luminance (standard 80%, deviant 20%) were presented randomly, where two task difficulties (easy, difficult) were defined by target/nontarget discriminability. An increase in task difficulty enhanced P3a as well as a posterior negativity (change-related negativity) and an anterior positivity (frontal positivity) elicited by deviant nontarget stimuli. These results suggest that attentional modulation of refractoriness-based rareness detection and an attention-triggering process underlie the P3a task-difficulty effect.     

The neural process of hazard perception and evaluation for warning signal words: Evidence from event-related potentials

Warning signs have been widely applied to industrial production. As an important component of warning signs, warning signal words were mostly studied by using questionnaire. This study used event-related potentials (ERPs) to explore neural temporal features during the processing of warning signal words in human brain, and found that there were two stages involved in processing warning signal words, providing an electrophysiological evidence for a previous warning information processing model, the Communication-Human Information Processing Model (C-HIP). Previous behavioral studies indicated that the subjective hazard perception of participants facilitates their attention to the warning sign, and people can get hazard information from warning words. Our results provided direct evidence for these conclusions. The present findings of significant differences in subjective hazard perception for warning words among individuals showed the importance and necessity of training for people to get the similar understanding of these words. Our results implicated that the warning words reflecting the same hazard level used in the warning sign should be somewhat changed, at the same time, convey equally or similarly hazardous information, to avoid desensitization and habituation due to overuse of them.     

Temporal auditory processing at 17 months of age is associated with preliterate language comprehension and later word reading fluency: An ERP study

Dyslexia is heritable and associated with auditory processing deficits. We investigate whether temporal auditory processing is compromised in young children at-risk for dyslexia and whether it is associated with later language and reading skills. We recorded EEG from 17 months-old children with or without familial risk for dyslexia to investigate whether their auditory system was able to detect a temporal change in a tone pattern. The children were followed longitudinally and performed an intelligence- and language development test at ages 4 and 4.5 years. Literacy related skills were measured at the beginning of second grade, and word- and pseudo-word reading fluency were measured at the end of second grade. The EEG responses showed that control children could detect the temporal change as indicated by a mismatch response (MMR). The MMR was not observed in at-risk children. Furthermore, the fronto-central MMR amplitude correlated with preliterate language comprehension and with later word reading fluency, but not with phonological awareness. We conclude that temporal auditory processing differentiates young children at risk for dyslexia from controls and is a precursor of preliterate language comprehension and reading fluency.     

Dipole Localization and Test-Retest Reliability of Frequency and Duration Mismatch Negativity Generator Processes

The mismatch negativity (MMN) is an event related potential component elicited by changes in duration, frequency or intensity of the stimuli during repetitive series of equal standard stimuli. In the present study we compared duration and frequency MMN using dipole source analysis concerning both the test-retest reliability of MMN-amplitudes and the locations of the potential sources. Furthermore, the influence of attention for test-retest-reliability was studied. Therefore, two groups of healthy subjects were investigated with different attentional manipulations. Twenty-one healthy subjects had to perform a visual attention task during the recording and 21 healthy subjects had no additional task to perform. All subjects were studied twice with a time interval of 3 weeks. Test-retest reliability was sufficiently high for the frequency but slightly lower for the duration MMN. The locations of the frequency and duration MMN-dipoles were in the auditory cortex with a more anterior and caudal location for the frequency MMN-dipoles. The latter finding supports the hypothesis that the frequency and duration MMNs have separate neuronal generators.     

Emotional content modulates response inhibition and perceptual processing

In this study, event‐related potentials were used to investigate the effect of emotion on response inhibition. Participants performed an emotional go/no‐go task that required responses to human faces associated with a “go” valence (i.e., emotional, neutral) and response inhibition to human faces associated with a “no‐go” valence. Emotional content impaired response inhibition, as evidenced by decreased response accuracy and N2 amplitudes in no‐go trials. More importantly, emotional expressions elicited larger N170 amplitudes than neutral expressions, and this effect was larger in no‐go than in go trials, indicating that the perceptual processing of emotional expression had priority in inhibitory trials. In no‐go trials, correlation analysis showed that increased N170 amplitudes were associated with decreased N2 amplitudes. Taken together, our findings suggest that emotional content impairs response inhibition due to the prioritization of emotional content processing.     

Neuroelectric indices of goal maintenance following a single bout of physical activity

Previous event-related brain potential (ERP) investigations have demonstrated that single bouts of physical activity have transient benefits to aspects of cognitive control. However, this line of research has yet to explore goal maintenance. ERPs were collected using a within-participants design with young-adults following 30-min of both moderate walking and a non-exercise control session. Participants completed three conditions of an AX-continuous performance task (AX-CPT) that targeted goal maintenance processes, which were placed under greater cognitive demand when contexts were conflicting, as indexed by modulation of the N2 and P3 components. Following exercise, individuals exhibited increased accuracy for target trials, and P3 amplitude was greater at midline-parietal sites for both target trials and non-target trials. These results suggest that a single bout of aerobic exercise may facilitate goal maintenance processes and enable individuals to better inhibit extraneous neural activity to allocate greater attentional resources towards the updating and revision of goal representations.     

Minding the PS, queues, and PXQs: uniformity of semantic processing across multiple stimulus types

An assumption in the reading literature is that access to semantics is gated by stimulus properties such as orthographic regularity or familiarity. In the electrophysiological domain, this assumption has led to a debate about the features necessary to initiate semantic processing as indexed by the N400 event-related potential (ERP) component. To examine this, we recorded ERPs to sentences with endings that were familiar and legal (words), familiar and illegal (acronyms), or unfamiliar and illegal (consonant or vowel strings). N400 congruency effects (reduced negativity to expected relative to unexpected endings) were observed for words and acronyms; these were identical in size, timing, and scalp distribution. Notably, clear N400 potentials were also elicited by unfamiliar, illegal strings, suggesting that, at least in a verbal context, semantic access may be attempted for any letter string, regardless of familiarity or regularity.     

P300 and alpha event-related desynchronization (ERD)

In the present study we evaluated the relationships between the P300 event-related potential and event-related desynchronization (ERD) of electroencephalographic alpha activity by simultaneously analyzing P300 as well as 7-10- and 10-14-Hz alpha ERD responses from auditory passive and active oddball conditions. We compared the effects of task (target vs. nontarget) and electrode (Fz, Cz, Pz) on P300 and ERD, and correlated P300 amplitude/latency with ERD maximal amplitude/latency across individuals. The major findings were that P300 as well as slow and fast alpha ERD manifested similar task and electrode effects. P300 preceded ERD and predicted individual variance of both slow and fast alpha ERD. The relationships of P300 with alpha ERD were different for the slow and fast alpha frequencies. These findings indicate that P300 and ERD are related such that slow and fast alpha ERDs are specifically guided or modified by the internal event(s) indexed by P300.     

Electrophysiological evidence of facial inversion with rapid serial visual presentation

Using measurements of event-related potentials (ERPs) during a facial recognition task, we aimed to investigate the facial inversion effect and the role of time-based attention in processing upright and inverted faces. We presented upright and inverted faces at the T2 (target 2) position using a rapid serial visual presentation paradigm. Our results indicate that the N170 component shows the usual face inversion effect (FIE), in which inverted faces elicit larger N170 amplitudes and a longer elicit N170 latency. We also found that upright faces elicit larger P1 amplitudes than inverted faces over the left hemisphere. This study indicates that the N170 and P3, but not the P1, components are modulated by time-based attention. In addition, we found that the N170 amplitude was modulated by an attentional blink (AB) based on behavioral data. These results suggest that the disruption of facial configuration processing caused by inverted faces is relatively independent of attentional resources.     

The case of letter rhyming: an ERP study

Previous visual event-related potential (ERP) studies using prime-target pairs of word and pseudoword stimuli have reported a robust rhyming effect such that nonrhyming targets elicit a larger N450 than rhyming targets. However, results of similar studies using simpler linguistic stimuli-single letters-are equivocal. We used lowercase and uppercase letter pairs in a simple ERP prime-target rhyming paradigm to further investigate whether single letters could elicit the typical rhyming effect and, if so, whether the rhyming effect was sensitive to physical orthography (which differed between the case conditions). The typical N450 rhyming effect was observed in both the lowercase and uppercase letter pair conditions, with similar amplitude and latency between conditions. This pattern of results suggests that the N450 rhyming effect is not sensitive to physical (case) orthography and likely primarily indexes phonological processing related to the rhyme task.     

Brain Potentials Related to Stages of Sentence Verification

Subjects were shown the terms of simple sentences in sequence (e.g., “A sparrow / is not / a vehicle”) and manually indicated whether the sentence was true or false. When the sentence form was affirmative (i.e., “X is a Y”), false sentences produced scalp potentials that were significantly more negative than those for true sentences, in the region of about 250 to 450 msec following presentation of the sentence object. In contrast, when the sentence form was negative (i.e., “X is not a Y”), it was the true statements that were associated with the ERP negativity. Since both the false-affirmative and the true-negative sentences consist of “mismatched” subject and object terms (e.g., sparrow / vehicle), it was concluded that the negativity in the potentials reflected a semantic mismatch between terms at a preliminary stage of sentence comprehension, rather than the falseness of the sentence taken as a whole. Similarities between the present effects of semantic mismatches and the N400 associated with incongruous sentences (Kutas & Hillyard, 1980) are discussed. The pattern of response latencies and of ERPs taken together supported a model of sentence comprehension in which negatives are dealt with only after the proposition to be negated is understood.