Reliability of the task-related component (P3b) of P3 event-related potentials

Abstract Within session and between session reliabilities of the task-related component (P3b) of the P3 measures (amplitude, area and latency) and their habituation across eight sessions separated by 7–10 days, except for an interval of 1 month between the 6th and 7th sessions, were studied based on the difference waves, which were obtained by subtracting the ignored infrequent event-related potentials (ERP) from the target ERP elicited by a standard auditory oddball paradigm with eyes-open or eyes-closed conditions in 10 normal subjects. The within session reliabilities represented as Pearson correlation coefficients ( r ) were 0.57-0.66 for the three measures except for those for the latency and amplitude under the eyes-closed condition. The between session reliabilities expressed as intraclass correlation coefficients ( R ) ranged from 0.54 to 0.60 except for that for latency under eyes-closed conditions. Long-term habituation occurred within the first six sessions for the P3b amplitude and area, and dishabituation took place in the 7th session after an interval of 1 month, whereas no such phenomenon was observed for the P3b latency. Implications of the present results are discussed in terms of the clinical application of the P3 measures.     

P300 component of the auditory event-related potentials and dyslexia

Ten normal children (mean age = 9 years) and 12 dyslexic children (mean age = 8.1 years) were compared for latency, amplitude and topographic distribution of both parameters of P300. We found a significant increase in P300 latency in the dyslexic group. Noteworthy is the increase in amplitude in the central parietal area in the control group. These facts and their incidence are discussed in the present study.     

The effects of aging on the P3 component of the visual event-related potential

Visual stimuli were used to elicit ERPs in 108 normal subjects ranging in age from 8 to 90 years. Age-related differences were found for both P3 latency and amplitude. Children and elderly adults were found to have the latest P3s. The earliest P3s were found in subjects in their twenties. A curvilinear function best described the P3 latency/age relationship. Also, small but significant differences were observed between males and females in P3 latency. The relationship between P3 amplitude and age was strongly influenced by scalp location. P3 was largest at posterior electrode sites, but was not visible at frontal sites in young children. With increasing age P3 decreased in amplitude at the posterior sites and increased in amplitude at more frontal locations.     

The P300 component of event-related potentials in schizophrenic patients

In a pilot study, the P300 component of the ERP subsequent to competitive visual stimulation was examined in 12 schizophrenic patients (paranoid hallucinatory schizophrenia in partial remission, neuroleptic medication). In the competitive stimulation with a varying information content of the non-target stimuli, healthy probands showed a distinct increase in the amplitude of the P300 components according to a in the frequency of the non-target stimuli. The P300 components during these changing stimulatory conditions remained constant in the schizophrenic patients. This reduction in the reactivity of the P300 component subsequent to an increasing information content of the non-target stimuli can be interpreted as a disturbance in the selective information processing. The ability to adequately react to the information content of irrelevant stimuli appears to be reduced in the schizophrenic patients we examined.     

Cholinergic modulation of human P3 event-related potentials

A paradigm for studying relations between behavioral, neurochemical, and electrophysiologic processes is presented. Scopolamine, a centrally acting anticholinergic agent, abolished the human auditory P3 event-related potential, but had no measurable effect on the pattern reversal visual evoked potential or alpha rhythm. Recent memory was significantly impaired, but assessment of digit span, reaction time, and distant memory showed no impairment. Physostigmine, an anticholinesterase, restored the P3 and reversed the recent memory impairment. These results strongly suggest a cholinergic role in generation of P3 potential and support the concept that P3 generation is related to memory processes.     

Delayed P3 event-related potentials (ERPs) in thalamic hemorrhage.

Delayed P3 ERPs were recorded with an acoustic oddball paradigm in 5 patients affected by unilateral thalamic hemorrhage. P3 latencies in these 5 patients were above the normal mean latency of age-matched controls +2/+3 S.D.s. The P3 delay was persistent in serial follow-ups at 6 months from stroke. Normal P3 latencies were instead recorded in 4 patients with paramedian hemorrhage not involving or only partially involving the thalamus.     

Greater sensitivity of the P300 component to bimodal stimulation in an event-related potentials oddball task

ObjectiveStudies that explore neurophysiological correlates of psychiatric disorders have commonly used event-related potentials during a visual or an auditory oddball task with the main results being changes in the P300 component. In the present study, a bimodal oddball design with synchronized pairs of audio–visual stimuli was used to further improve the clinical sensitivity of the P300.MethodsTwo groups of healthy participants, one consisting of students displaying anxious–depressive tendencies and the other of control students, completed visual, auditory and two kinds of audio–visual oddball task (one using emotional stimuli and the other using geometrical figures and simple sounds), in which they had to detect deviant rare stimuli among more frequently presented standard stimuli as quickly as possible. Behavioral performance and P300 data were analyzed.ResultsThe subjects with anxious and depressive tendencies had lower P300 amplitudes than controls, but only in the bimodal tasks.ConclusionsAlthough the two groups differed in their levels of anxiety and depression, only the bimodal tasks were able to identify these differences.SignificancesThese results suggest that a bimodal oddball design should be used in future studies to increase the sensitivity of P300 differences for differentiating between healthy participants and those with clinical symptoms.     

Actively and passively evoked P3 latency of event-related potentials in Parkinson's disease.

Event-related potentials (ERPs) generated during the performance of visual discrimination tasks were studied in 31 patients with Parkinson's disease, 9 patients with Alzheimer's disease, and 37 normal control subjects. Actively and passively evoked P3 components (P3b and P3a) were respectively identified as the components of the P3 response to infrequent target stimuli and infrequent non-target stimuli. Both the P3a and P3b latencies were significantly prolonged by normal aging. Nine of the Parkinson's disease patients showed a P3b latency above the 95% confidence limit of the age-adjusted regression line based on the normal controls, while only on patient had a prolonged P3a latency. In 6 patients with demented Parkinson's disease, the P3b latency was significantly longer than in 15 age-equivalent normal subjects, although no significant difference was found in the P3a latency. On the other hand, patients with Alzheimer's disease showed significant prolongation of both the P3a and P3b latencies compared to the normal controls. Furthermore, there was a significant difference in P3a latency between patients with demented Parkinson's disease and those with Alzheimer's disease. These results suggest that the automatic processing stage associated with P3a may be less impaired than the attention-controlled processing reflected by P3b in patients with Parkinson's disease, and also indicate that there may be some differences in the changes of cognitive processing caused by Parkinson's disease and Alzheimer's disease.     

Delayed P3 event-related potentials (ERPs) in thalamic hemorrhage

Delayed P3 ERPs were recorded with an acoustic oddball paradigm in 5 patients affected by unilateral thalamic hemorrhage. P3 latencies in these 5 patients were above the normal mean latency of age-matched controls +2/ +3 S.D.s. The P3 delay was persistent in serial follow-ups at 6 months from stroke. Normal P3 latencies were instead recorded in 4 patients with paramedian hemorrhage not involving or only partially involving the thalamus.     

Impact of threat relevance on P3 event-related potentials in combat-related post-traumatic stress disorder.

The purpose of this study was to examine electrophysiological response to trauma-relevant stimuli in combat-related post-traumatic stress disorder (PTSD). Study design incorporated comparison of 10 Vietnam War veterans with PTSD diagnosis to 10 Vietnam War veterans with no mental disorder diagnosis on P3 components in a series of two oddball tasks (trauma-relevant threat, trauma-irrelevant threat) counterbalanced for order. Each task included high probability emotionally neutral distractor words and low probability neutral target words, but differed in the content of low probability threat words. Whereas threat words in the trauma-relevant oddball task pertained directly to combat trauma, threat words in the trauma-irrelevant oddball task were socially threatening words. Results revealed that, in comparison to healthy combat veterans, those diagnosed with PTSD demonstrated: (a) attenuated P3 response to neutral target items at selected electrode sites across both oddball tasks; and (b) increased responsivity to trauma-relevant combat stimuli but not to trauma-irrelevant social-threat stimuli at frontal electrode sites (F3, F4). Results are consistent with resource allocation models of PTSD, which suggest that PTSD is characterized by attentional bias to threat stimuli at the expense of attention to emotionally neutral information.     

Warp-averaging event-related potentials.

OBJECTIVE: To align the repeated single trials of the event-related potential (ERP) in order to get an improved estimate of the ERP. METHODS: A new implementation of the dynamic time warping is applied to compute a warp-average of the single trials. The trilinear modeling method is applied to filter the single trials prior to alignment. Alignment is based on normalized signals and their estimated derivatives. These features reduce the misalignment due to aligning the random alpha waves, explaining amplitude differences in latency differences, or the seemingly small amplitudes of some components. RESULTS: Simulations and applications to visually evoked potentials show significant improvement over some commonly used methods. CONCLUSIONS: The new implementation of the dynamic time warping can be used to align the major components (P1, N1, P2, N2, P3) of the repeated single trials. The average of the aligned single trials is an improved estimate of the ERP. This could lead to more accurate results in subsequent analysis.     

Auditory event-related potentials (P300) in epileptic patients.

Auditory event-related potentials (AERPs) were recorded during an auditory oddball paradigm in 108 epileptics and in 32 healthy controls. P300 latency varied in relationship with age only in controls. Symptomatic epileptics had significantly prolonged P300 mean latency compared to those without detectable brain lesion(s) on MR scan. Moreover, these latter patients were compared on the basis of epilepsy duration, type of seizure, seizure frequency and antiepileptic treatment; the application of a multiple regression model showed a significant relationship between P300 latency prolongation and epilepsy duration, seizure frequency and polytherapy.     

A negative component superimposed on event-related potentials during light drowsiness

The present study examined the nature of the negative shift of event-related potential (ERP) recorded during the fully awake state, wakefulness with minor awareness deficit (light drowsiness) and stage 1 of NREM sleep. The cortical responses evoked by two types of auditory stimuli were recorded in nine subjects at the different levels of consciousness described above. A negative component with peak latency of 250-350 msec, N300, was identified in ERP during light drowsiness but not in the fully awake state. In stage 1a (stage 1 without vertex sharp waves), the amplitude of N300 was higher than that in light drowsiness, and it was higher in stage 1b than in stage 1a. The scalp distribution of N300 was predominantly on the vertex. It also confirmed that the vertex sharp wave evoked during stage 1 is maximal on the vertex and its peak latency is approximately 300 msec. Considering the similarity in scalp distribution and peak latency between N300 and vertex sharp wave, it is possible that these electroencephalogram phenomena are generated by an identical synchronizing mechanism in the brain. We assumed that N300 observed during light drowsiness may be an incomplete product of vertex sharp wave.     

Recording of event-related potentials (P300) from human cortex.

Auditory event-related potentials were recorded simultaneously from chronically implanted subdural electrodes and from scalp electrodes in three patients who were being evaluated for surgical treatment of epilepsy. These three cases showed clearly defined scalp-P300 and scalp-N300. A cortex-P300 was recorded from the midtemporal area, and a cortex-N300 was recorded from the inferior frontal area with some reflection at the basal temporal region. There were no potentials from an interhemispheric region. We could not observe any component from the cortex studied corresponding to scalp-recorded N200. Therefore, while the activity generated from the mesial temporal lobe may only make minor contributions to scalp-P300, that generated from the midtemporal area might make a major contribution to the scalp-P300. Additionally, generators of N200, P300, and N300 are different from each other. These findings, together with previous reports regarding the generator source of P300, also suggest that P300 is a complex arising from multifactorial generator sources, including the midtemporal and inferior frontal area.     

The mismatch negativity and the P3a components of the auditory event-related potentials in autistic low-functioning subjects.

OBJECTIVE: In order to understand better the psychophysiological basis of auditory processing abnormalities in autism, we decided to study two automatic components of the auditory event-related potentials (ERPs): the mismatch negativity (MMN)--a component of the ERP which is recorded when, during repetitive auditory stimulation, rare changes are introduced--and the novelty-related P3a which is recorded as a response to unexpected novel events occurring in a sequence of repetitive stimuli. METHODS: Ten male subjects, mean age 12.3 years (SD 4.95), affected by autism and mental retardation were admitted to this study. All patients were also mentally retarded. Ten normal male subjects, mean age 12.2 years (SD 3.94), were used as controls. Auditory evoked potentials were recorded from 19 scalp electrodes (10-20 system), and stimuli were presented in sequences consisting of 2000 tones (70 dB, ISI=800 ms). Three types of stimuli were presented: (1) standard stimuli (1000 Hz tones, 80% of total stimuli), (2) deviant stimuli (1300 Hz tones, 10% of total stimuli), and (3) novel stimuli (complex and non-monotonal, 10% of total stimuli). To quantify the MMN, the evoked response to the standard tones was subtracted from the corresponding deviant stimulus response and its amplitude and latency at peak were measured over Fz, Cz and Pz; similarly, the P3a component of the ERP was obtained by subtracting the response to the standard tone from that to the novel stimuli and its amplitude and latency at peak were measured over Fz, Cz and Pz. Also, the amplitude and latency at peak for the N1 component of the auditory evoked potential obtained with the standard stimuli were measured over Fz, Cz and Pz. The correlation between age and MMN and P3a amplitude was also analyzed. RESULTS: N1 showed significantly shorter latencies in the autistic groups. MMN elicited by deviant stimuli, but not that elicited by novel stimuli, was found to be significantly larger in autistic children than in normal controls. P3a showed higher amplitude in autistic subjects than in normal controls during childhood; the opposite was observed during young adulthood. DISCUSSION: Our findings indicate that significant changes in ERPs can also be seen in non-cooperative individuals with autism and mental retardation, which might be different from the changes already reported for high-functioning autistic subjects and deserve further insight. These changes show developmental modifications that should be taken into consideration when analyzing data from autistic subjects.     

The effect of aging on auditory components of event-related brain potentials

OBJECTIVE: To describe auditory perceptual, pre-attentive, attention-related and cognitive processes along lifespan in normal people by a simple auditory oddball paradigm easily usable in clinical practice. METHODS: ERPs were recorded in 72 normal subjects. Four blocks of tones were delivered (20% rare 2,000 Hz and 80% frequent 1,000 Hz). In the former two blocks, subjects performed a concomitant distracting visual search task (distracted condition); in the latter two blocks, they had to attend the occurrence of the rare tones (active condition). Latency and amplitude of ERPs were analyzed according to age, gender, educational level and repetition. RESULTS: N100 amplitude was greater in active than in distracted condition. MMN amplitude decreased with age. N2b and P300 latencies increased with age, while their amplitudes decreased. Females produced greater P300 than males. In the elderly, P300 latency was found to be longer in the second block than in the first one. CONCLUSIONS: N100 and MMN were found to be less affected by age than N2b and P300. When repeated, P300 showed increased latency in elderly subjects. SIGNIFICANCE: The protocol detected the higher influence of aging on late cognitive processes than on the perceptual and pre-attentive ones. Age-adjusted normative data were produced.     

健康成人事件相关电位与神经心理学测验的相关性研究

目的 探讨事件相关电位P300的四个主要成分是否反映特定的认知功能。方法 将120名正常受试者按年龄分为三组，即20～34岁组、35～54岁组和55～70岁组，对所有受试者采用全套韦氏成人智力测验(WAIS-RC)等多项神经心理学测验以及P300进行测评，将神经心理学测验结果与P瑚结果进行Spearman等级相关分析。结果 三个年龄组中的N2潜伏期、P2波幅、N2波幅均与反映注意、短时记忆的神经心理学测验存在以下相关：在20～34岁组中，N2潜伏期与即刻视觉再生呈负相关(r=-0．352)，P2波幅与即刻视觉再生呈正相关(r=0．339)，N2波幅与即刻视觉再生呈正相关(r=0．331)。在35～54岁组中，N2潜伏期与数字广度、数字符号、词汇流畅均呈负相关(r分别=-0．357、-0．385、-0．316)；P2波幅与延线测验B呈负相关(r=-0．427)；Nl波幅与即刻逻辑记忆呈正相关(r=0．343)。在55～70岁组中，N2潜伏期与数字符号、词汇流畅呈负相关(r分别=-0．488和-0．321)，与延线测验B呈正相关(r=0．366)；P2波幅与数字符号呈正相关(r=0．314)；N2波幅与词汇流畅呈正相关(r=0．437)。在不同的年龄组中，P300的其他指标与神经心理学测验相关性不一致。结论 P300的四个主要成分可反映一定的认知功能，但不具有特异性，部分P300指标所反映的认知功能受年龄的影响。