Principal Component Analyses and Scalp Distribution of the Auditory P150–250 and N250–550 to Speech Contrasts in Mexican and American Infants

We report a Principal Component Analysis (PCA) and the scalp distribution of the normalized peak amplitude values for speech-related auditory Event-related Potentials (ERP) P150–250 and N250–550 in 7-, 11-, and 20-month-old American infants learning English and in 10–13-month-old Mexican infants learning Spanish. After assessing the infant auditory ERP P-N complex using PCA, we evaluated the topographic distribution of each of the discriminatory phases to native and non-native CV-syllabic contrasts used in Spanish and English. We found that the first two Principal Components for each contrast type across ages showing a maximization of differences between the P150–250 and the N250–550 waves, explain more than 70% of the variance. The scalp distributions of the P150–250 and N250–550 components also differed, the P150–250 showing a frontal and anterior temporal distribution, and the N250–550 a more posterior distribution. The older infants showed a broader distribution of responses, particularly for the N250–550. There were no differences in the topographies of the components between same-aged Mexican and American infants. We discuss the perceptual/linguistic functions that each component may reflect during development and across the two cultures.     

Intermodal selective attention: Evidence for processing in tonotopic auditory fields

Auditory event-related brain potentials (ERPs) were recorded for 250- and 4,000-Hz tone bursts in an intermodal selective attention task. Tonotopic changes were evident in the scalp distribution of the rising phase of the auditory N1 (mean peak latency 116 ms); the N1 was more frontally distributed following the 4,000-Hz than following the 250-Hz tone bursts, and it included a contralateral P90 component that was absent following 250-Hz tones. ERPs related to intermodal selective attention were isolated as negative and positive auditory difference waves (Nd_a and Pd_as). Neither the Nd_a nor the Pd_a showed changes in distribution with tone frequency, but both showed Ear × Frequency changes in distribution. ERPs for deviant tones included mismatch negativities (MMNs) and, in attend auditory conditions, N2b and P3 components. These components did not change in scalp distribution with tone frequency. One possible explanation is that tonotopic displacements of ERP distributions on the scalp surface depend on angular displacements in generator fields on gyral convexities. The results are consistent with the possibility that auditory processing radiates outward with increasing latency from tonotopic fields on Heschl's gyri to more gyrus-free regions of the planun temporale and anterior superior temporal plane.     

Auditory recognition memory in 2-month-old infants as assessed by event-related potentials

Previous studies of auditory recognition memory in sleeping newborns reported 2 event-related potential (ERP) components, P2 and negative slow wave (NSW), reflecting voice discrimination and detection of novelty, respectively. In the present study, using high-density recording arrays, ERPs were acquired from 26 2-month-old awake infants as they were presented with a familiar and unfamiliar voice (i.e., mother and stranger) with equal probability. In addition to P2 and NSW, we observed a positive slow wave (PSW) over the right temporo-parietal scalp, indicating memory updating. Our study suggests that infants appear to have the capacity to encode novel stimuli as early as 2 months of age.     

Auditory Recognition Memory in 2-Month-Old Infants as Assessed by Event-Related Potentials

Previous studies of auditory recognition memory in sleeping newborns reported 2 event-related potential (ERP) components, P2 and negative slow wave (NSW), reflecting voice discrimination and detection of novelty, respectively. In the present study, using high-density recording arrays, ERPs were acquired from 26 2-month-old awake infants as they were presented with a familiar and unfamiliar voice (i.e., mother and stranger) with equal probability. In addition to P2 and NSW, we observed a positive slow wave (PSW) over the right temporo-parietal scalp, indicating memory updating. Our study suggests that infants appear to have the capacity to encode novel stimuli as early as 2 months of age.     

Scalp topography of the auditory evoked K-complex in stage 2 and slow wave sleep

During NREM sleep a very large amplitude wave-form, known as the K-complex, may be elicited upon presentation of an external stimulus. The present study compared the scalp distribution of a prominent negative wave peaking at about 550 ms and a later positive wave peaking between 900 and 1300 ms in stage 2 and slow wave sleep (SWS). Nine subjects spent a single night in the laboratory. They were presented with an 80 dB SPL 2000 Hz auditory tone pip every 15 s. The EEG was recorded from 29 electrode sites and referenced to the nose. A K-complex was elicited on 34% of trials in stage 2 and on 46% of trials in SWS. A negative wave peaking at 330 ms was larger on trials in which the K-complex was elicited than on trials in which it was not. The large amplitude N550 was readily observable on trials in which the K-complex was elicited but could not be observed on trials in which it was not. The N550 was bilaterally symmetrical and was maximum over fronto-central areas of the scalp in both stage 2 and SWS. It inverted in polarity at the mastoid and inferior parietal regions. The scalp distribution of N550 significantly differed between stage 2 and SWS. It showed a sharper decline in amplitude over parietal and posterior-inferior areas of the scalp in stage 2 compared to SWS. A later P900 was maximum over centro-frontal areas of the scalp and was also bilaterally symmetrical. It showed a significantly sharper decline in amplitude over widespread inferior areas during SWS. Because the scalp maps of the N550 and P900 are different in stage 2 and SWS, their intracranial sources must also be different.     

A componential analysis of the ERP elicited by novel events using a dense electrode array.

In this study, we examined the relationship between the novelty P3 and the P300 components of the brain event-related potential (ERP). Fifteen subjects responded manually to the rare stimuli embedded either in a classical auditory oddball series or in a series in which "novel" stimuli were inserted. The electroencephalogram (EEG) was recorded with a dense array of 129 electrodes. The data were analyzed by using spatial Principal Components Analysis (PCA) to identify a set of orthogonal scalp distributions, "virtual electrodes" that account for the spatial variance. The data were then expressed as ERPs measured at each of the virtual electrodes. These ERPs were analyzed using temporal PCA, yielding a set of "virtual epochs." Most of the temporal variance of the rare events was associated with a virtual electrode with a posterior topography, that is, with a classical P300, which was active during the virtual epoch associated with the P300. The novel stimuli were found to elicit both a classical P300 and a component focused on a virtual electrode with a frontal topography. We propose that the term Novelty P3 should be restricted to this frontal component.     

Sequential processing of interaural timing differences for sound source segregation and spatial localization: evidence from event-related cortical potentials

Cortical processing of interaural timing differences (ITDs) was investigated with event-related potential (ERP) measurements in 16 human participants who were required in separate tasks to detect or to spatially localize dichotically embedded pitches. ITDs elicited three ERP components labeled ORN, N2, and P400. The ORN occurred at a latency of 150-250 ms and was elicited by ITDs regardless of location or task. In contrast, the N2 response (250-350 ms) was strongly modulated by location and showed larger amplitudes for the localization task than for the detection task. Finally, ITDs in the detection task elicited a P400 at a latency of 400-500 ms, but this response was entirely absent from ERPs elicited by identical stimuli in the localization task. These results are consistent with a sequential model of auditory perception in which segregation of concurrent sounds is followed by domain-specific processing of object location and identity.     

EEG frequency PCA in EEG‐ERP dynamics

Principal components analysis (PCA) has long been used to decompose the ERP into components, and these mathematical entities are increasingly accepted as meaningful and useful representatives of the electrophysiological components constituting the ERP. A similar expansion appears to be beginning in regard to decomposition of the EEG amplitude spectrum into frequency components via frequency PCA. However, to date, there has been no exploration of the brain's dynamic EEG‐ERP linkages using PCA decomposition to assess components in each measure. Here, we recorded intrinsic EEG in both eyes‐closed and eyes‐open resting conditions, followed by an equiprobable go/no‐go task. Frequency PCA of the EEG, including the nontask resting and within‐task prestimulus periods, found seven frequency components within the delta to beta range. These differentially predicted PCA‐derived go and no‐go N1 and P3 ERP components. This demonstration suggests that it may be beneficial in future brain dynamics studies to implement PCA for the derivation of data‐driven components from both the ERP and EEG.     

The effect of age on event-related potentials (ERP) associated with face naming and with the tip-of-the-tongue (TOT) state

This study examined the effects of aging on the ERP components associated with the different processing stages in a face naming task. Two hundred photographs were presented to 13 young and 10 elderly adults, who had to press a button and then to say the name aloud (KNOW condition), or “Can’t remember” if they were experiencing a tip-of-the-tongue state (TOT condition). Young adults showed larger ERP amplitudes in KNOW than in TOT in the 550-750 and 1550-2000 ms intervals, but the older adults did not show any such differences. The older adults showed a specific lengthening in ERP latencies from 250 ms onwards, and smaller mean amplitudes in the 550-750 ms interval in the KNOW category and in the 750-1000 ms interval in both categories, and a wider and more frontalized scalp topographical distribution of the ERP amplitudes than the young adults. The results may indicate activation of compensatory mechanisms in elderly adults.     

Separability of Different Negative Components of the Event-Related Potential Associated with Auditory Stimulus Processing

The lateral scalp distribution of the early negative selective-attention effect on auditory eventrelated potentials (ERPs) was compared to the distribution of the midline-negative N1 component inverting in polarity at the scalp area below the Sylvian fissure. No such polarity inversion was observed for the selective-attention effect at the N1 latency. This result supports the proposal that another component, the processing negativity (PN), overlaps (summates to) the exogenous N1 in the ERPs to attended stimuli. A subsequent experiment demonstrated that the mismatch negativity (MMN: peaking at 150–200 ms), an ERP component automatically elicited by deviant stimuli presented among homogenous repetitive stimuli, had opposite polarities above and below the Sylvian fissure. Thus, the MMN at least partly emanates from a cerebral generator which considerably overlaps that of the N1. The results are discussed in terms of separability of the brain mechanisms involved in the voluntary and involuntary processing of auditory stimuli reflected by the PN and MMN, respectively.     

Developmental Evidence for Modality-Dependent P300 Generators: A Normative Study

The behavior of the early and late components of the event-related brain potential (ERP) elicited by auditory and visual stimuli was studied in 40 normal females between the ages of 7 and 20. The ERPs were collected using two different tasks (i.e.,count and reaction time) in an oddball paradigm. Analysis of the early component (i.e., N1, P2, N2) latencies revealed small but significant decreases with age in the visual modality but no change in the auditory modality. Except for the visual N1, early component amplitudes did not change significantly over this age range. The results showed that auditory and visual P300 latencies, but not amplitudes, changed at significantly different rates over this age range. P300 latencies in the auditory modality showed a relatively abrupt change around age 12, after which P300 latencies changed little and were essentially at their adult levels. The latencies of visual P300s showed a much smaller and more steady decrease with age. Thus visual P300 latencies were shorter than auditory P300s in young children but longer than auditory P300s in older children. Significantly different scalp distributions were found for auditory and visual P300s. Although all P300 activity was maximal over parietal scalp, visual P300s were significantly larger than auditory P300s over central and frontal scalp. The developmental differences, combined with the presence of significantly different scalp topographies for auditory and visual P300s, provide convergent evidence that P300 activity is not independent of the modality of the eliciting stimulus.     

Using principal components analysis to examine resting state EEG in relation to task performance

Brain dynamics research has highlighted the significance of the ongoing EEG in ERP genesis and cognitive functioning. Few studies, however, have assessed the contributions of the intrinsic resting state EEG to these stimulus‐response processes and behavioral outcomes. Principal components analysis (PCA) has increasingly been used to obtain more objective, data‐driven estimates of the EEG and ERPs. PCA was used here to reassess resting state EEG and go/no‐go task ERP data from a previous study (Karamacoska et al., 2017) and the relationships between these measures. Twenty adults had EEG recorded with eyes closed (EC) and eyes open (EO), and as they completed an auditory go/no‐go task. Separate EEG and ERP PCAs were conducted on each resting condition and stimulus type. For each state, seven EEG components were identified within the delta‐beta frequency range, and six ERP components were obtained for go and no‐go stimuli. Within the task, mean reaction time (RT) correlated positively with go P2 amplitude and negatively with P3b positivity. Regressions revealed that greater EC delta‐1 amplitude predicted shorter mean RT, and larger alpha‐3 amplitude predicted go P3b enhancement. These findings demonstrate the immediate P2 and P3b involvement in decision making and response control and the intrinsic EC delta‐1 and alpha‐3 amplitudes that underpin these processes.     

Effects of Age and Sex on the Endogenous Brain Potential Components During Two Continuous Performance Tasks

Event-related potentials (ERPs) were recorded during two versions of the continuous performance test (CPT) from 74 adolescents grouped into 6 yearly age intervals (12–17) in a cross-sectional study of the effects of age and sex on the cognitive ERPs. The two CPTs differed in their processing complexity, with Task B requiring an additional stage of information processing not needed for performance on Task A. The effects of Stimulus (Signal/Non-Signal), Task (A/B), and Electrode Location (F_Z/C_Z/P_Z/O_Z) were highly similar to those reported by Friedman, Vaughan, and Erlen-meyer-Kimling (1981) for a subsample (N = 30) of this group of subjects. New findings were highlighted by the analyses of the effects of age and sex on the six electrophysiological events (N150, P240, P350, P450, P550, Slow Wave) recorded during these CPTs. Principal Components Analysis (PCA) was used in an attempt to reduce overlap among components, with the factor scores compared to the baseline to peak measures. Modest age effects were found for P450 (classical P300), with the pattern of findings suggestive of differences in processing strategies between the older and younger adolescents. PCA performed on the first 408 ms of the ERP epoch yielded a component corresponding to an early-onset endogenous negativity which showed a decrease in amplitude with increments in chronological age. Effects of sex were found for P550 and Slow Wave. While the pattern of results may indicate differences between males and females in cognitive processing mode, the design of these CPTs does not allow a functional association between these components and the modes of processing that have been reported to differentiate males and females. The data highlight the importance of including age and sex as variables whenever investigations of cognitive ERPs are undertaken.     

The Relation between Infant Covert Orienting,Sustained Attention and Brain Activity

This study used measures of event-related potentials (ERPs) and cortical source analysis to examine the effect of covert orienting and sustained attention on 3- and 4.5-month-old infants’ brain activity in a spatial cueing paradigm. Cortical source analysis was conducted with current density reconstruction using realistic head models created from age-appropriate infant MRIs. The validity effect was found in the P1 ERP component that was greater for valid than neutral trials in the electrodes contralateral to the visual targets when the stimulus onset asynchrony (SOA) was short. Cortical source analysis revealed greater current density amplitude around the P1 peak latency in the contralateral inferior occipital and ventral temporal regions for valid than neutral and invalid trials. The processing cost effect was found in the N1 ERP component that was greater for neutral than invalid trials in the short SOA condition. This processing cost effect was also shown in the current density amplitude around the N1 peak latency in the contralateral inferior and middle occipital and middle and superior temporal regions. Infant sustained attention was found to modulate infants’ brain responses in covert orienting by enhancing the P1 ERP responses and current density amplitude in their cortical sources during sustained attention. These findings suggest that the neural mechanisms that underpin covert orienting already exist in 3- to 4.5-month-old, and they could be facilitated by infant sustained attention.     

The N550 component of the evoked K-complex: A modality non-specific response?

A large amplitude late negative deflection peaking between 500 and 650 ms is observable in the averaged K-complex wave-form. This peak is thus often labelled the N550. 'N550' appears during stage 2 and is maintained into slow wave sleep but is not apparent during REM. Most studies have employed auditory stimuli to elicit the K-complex. Two experiments were run to examine the effects of stimulus modality on the topographical distribution of the N550. In the first experiment, the K-complexes were elicited in an auditory oddball procedure. In the second experiment, K-complexes were elicited by respiratory occlusions. Twenty-nine channel recordings were used to increase spatial resolution. N550 was substantially larger in the average of trials containing K-complexes than in trials in which a K-complex could not be identified. N550 varied inversely in amplitude with the probability of accordance of the stimulus. The topographic distribution of the N550 was consistent between experiments. It was bilaterally symmetrical and was maximal over fronto-central regions of the scalp. The results indicate that the N550 reflects the activity of a modality non-specific, sleep dependent generator that responds to both interoceptive and external stimulation.     

Effects of aging on event-related brain potentials and reaction times in an auditory oddball task

Auditory event-related potentials (ERPs) were recorded from 71 healthy individuals between 18 and 82 years of age during performance of a disjunctive reaction time task in an auditory oddball paradigm. The effects of aging on reaction times and on the latencies, amplitudes, and distributions of each of the main ERP components were examined. No significant slowing of the reaction times of the elderly subjects was observed in relation to the younger ones. The peak latencies of both the N1 and P2 components elicited by standard tones were slightly but significantly slowed with age. In the ERPs of target tones, the later, endogenous components (N2, P3, and SW) showed linear increases in latency as a function of age; the later the component, the longer the age-related delay. In general, aging was associated with less negativity (both N2 and SW) and more positivity (P3) over the anterior scalp, together with a smaller P3 and a more pronounced N2 over posterior scalp areas. Most of the effects observed in target ERPs were also evident in the difference waves derived from subtraction of the standard from the target ERPs, although the slope of the age-related latency increase of N2 was shallower and that of the P3 was steeper in the difference ERPs. These findings are discussed in relation to previous accounts of ERP changes with aging.     

The development of stop-signal and Go/Nogo response inhibition in children aged 7-12 years: performance and event-related potential indices.

The present study examined the development of response inhibition during the Stop-signal and Go/Nogo tasks in children using performance and ERP measures. Twenty-four children aged 7 to 12 years completed both tasks, each with an auditory Nogo/Stop-signal presented on 30% of trials. On average, response inhibition was more difficult in the Stop-signal than Go/Nogo task. Response inhibition performance did not develop significantly across the age range, while response execution varied significantly in a task dependent manner (Go/Nogo: increasing accuracy and reducing response variability with age; Stop-signal: reducing Go mean reaction time and response variability with age). The N1, P2, N2 and P3 components showed different scalp distributions, with N1 and P2 peaking earlier, and P3 later, in Nogo compared to Stop stimuli. N2 and P3 amplitude were positively correlated with successful inhibition probability in the Go/Nogo task only. N2 amplitude and latency to both Nogo and successful Stop stimuli decreased linearly with age, but not in the frontal regions. N1 and P3 amplitude in the parietal region increased with age for Stop-signals. An age-related reduction in P3 latency to Nogo stimuli correlated significantly with reduced RT and variability in Go responding, indicating a relationship between efficient Nogo and Go processing. Together the behavioural and ERP results suggest little development of the response inhibition process as measured via the Stop-signal and Go/Nogo tasks across the 7 to 12 year age range, while response execution processes develop substantially.     

ERP components reflecting stimulus identification: contrasting the recognition potential and the early repetition effect (N250r).

The recognition potential component (RP) in the event-related brain potential (ERP) appears during rapid stream stimulation and has been related to the activation of word form or word meaning. The early repetition effect (ERE/N250r) is observed in repetition priming designs and has been linked to the access to stored representations of the structure of familiar faces and names. Because of the apparent similarities in latency, topography and theoretical interpretation we compared the RP and ERE/N250r within the same rapid stream stimulation design and for the same type of stimulus material: names and faces of famous persons and names and pictures of common objects. Contrasting with RP, the ERE/N250r occurred later and differed in both scalp topography and amplitude patterns across stimulus conditions. Therefore, the ERE/N250r seems to reflect a separate and content-specific stage of information processing, following the RP, which appears to reflect domain-general processes of structural analyses.     

The time course of orthography and phonology: ERP correlates of masked priming effects in Spanish

One key issue for computational models of visual-word recognition is the time course of orthographic and phonological information during reading. Previous research, using both behavioral and event related brain potential (ERP) measures, has shown that orthographic codes are activated very early but that phonological activation starts to occur immediately afterward. Here we report an ERP masked priming experiment in Spanish that investigates this issue further by using very strict control conditions. The critical phonological comparison was between two pairs of primes having the same orthographic similarity to the target words but differing in phonological similarity (e.g., conal - CANAL vs. cinal - CANAL vis à vis ponel - PANEL vs. pinel - PANEL ), whereas the critical orthographic contrast was between pairs of primes that had the same phonological similarity to the target but differing in orthographic similarity (e.g., conal - CANAL vs. konal - CANAL ). Orthographic priming was mainly observed in the 150–250-ms time window whereas phonological priming occurred in the 350–550-ms window.     

P300 topography of amplitude/latency correlations

Summary The correlational association from 19 electrode sites between peak amplitude and latency for the P3(00) event-related brain potential (ERP) for n=80 homogeneous subjects was assessed using a simple auditory discrimination task. The correlation strength varied systematically across scalp topography in different ways for the various ERP components. For the target stimuli, P3 amplitude and latency were negatively correlated and most tightly coupled over the frontal-central and right medial/lateral recording sites. In contrast, the N1 produced negative correlations that were strongest over the left and right central/lateral locations; P2 demonstrated a positive correlation that was strongest frontally and centrally; N2 demonstrated a positive correlations that was strongest over the central and parietal sites. ERPs from the standard stimuli produced generally similar patterns for the P3 and P2 components, with only weak or no reliable effects observed for the N1 and N2 potentials. Taken together, the findings suggest that analysis of amplitude/latency correlational relationships can provide information about ERP component generation. Theoretical implications are discussed.Collaborative studies on the Genetics of Alcoholism (H. Begleiter, SUNY HSCB, Principal Investigator, T. Reich, Washington University, Co-Principal Investigator) includes six different centers where data collection takes place. The six sites and Principal Investigator and Co-Investigators are: Indiana University (J. Nurnberger, Jr., P.M. Conneally); University of Iowa (R. Crow, S. Kuperman); University of California, San Diego and The Scripps Research Institute (M. Schuckit, F.E. Bloom); University of Connecticut (V. Hesselbrock); State University of New York, Health Science Center at Brooklyn (H. Begleiter, B. Porjesz); Washington University in St. Louis (T. Reich, C.R. Cloninger). This national collaborative study is supported by the National Institute on Alcohol Abuse and Alcoholism (NIAAAA) by U.S.P.H.S. grant U10AA08402-07, This paper is publication number NP10292 from The Scripps Research Institute.