The long and the short of it: influence of interstimulus interval on auditory P300 abnormalities in schizophrenia.

Event-related brain potentials were recorded from 10 patients with DSM-IV schizophrenia (9 men) and 10 healthy control subjects (9 men) during the performance of two auditory oddball tasks, one using a 1.5 second interstimulus interval (ISI), the other using an 8 second ISI. P300 amplitude to target tones (.20 probability) and standard tones (.80 probability) were measured from midline electrodes Fz, Cz, and Pz. Results showed different effects of ISI in the two groups. Controls showed a slight decrease in P300 amplitude to targets but a marked increase in P300 to standards with the increase in ISI. In contrast, schizophrenic patients showed no change in the P300 to targets and a relatively small increase in P300 to standards with the ISI increase. Moreover, relative to the controls, P300 amplitude to targets was reduced in the schizophrenic patients at the short but not the long ISI. Implications for the cognitive significance of the P300 and its reduction in schizophrenia are discussed.     

Influence of reference electrodes, stimulation characteristics and task paradigms on auditory P50

Abstract To clarify the nature of auditory P50, middle latency auditory evoked potentials were recorded by using different conditions of reference electrodes (linked earlobes, LE; balanced non-cephalic, BN), stimulation characteristics (tone burst, human voice) and tasks (counting, simple reaction) in 10 right-handed males (aged 21–36 years). EEG was recorded from Fz, Cz, Pz, C3, C4, T3 and T4 according to the 10–20 system. Two groups of electrode sites were made for the statistical analysis: a midline group, Fz, Cz and Pz; and a lateral group, T3, C3, Cz, C4 and T4. The results were that the P50 amplitudes with BN electrodes were significantly higher than those with LE in both groups (midline, P < 0.01; lateral, P < 0.01); the P50 amplitudes by voice stimulation were significantly higher than those by tone stimulation in the lateral group ( P < 0.05), and the P50 latencies under a simple reaction paradigm were significantly shorter than those under a counting task in both groups (midline, P < 0.05; lateral, P < 0.05). These results suggest that various factors including motor response affect the P50 amplitudes and latencies.     

Long-term olanzapine treatment and p300 parameters in schizophrenia

The well-known amplitude reduction of the P300 appears to be unaffected by the treatment with classical antipsychotics in schizophrenia, whereas the effects of atypical neuroleptics on this event-related potential are less understood. The study of these changes could help in deciding whether the P300 amplitude reduction in schizophrenia is a trait or state marker of that illness and in better describing the effect of atypical antipsychotics on altered cognitive functions. We present a prospective longitudinal study of P300 amplitude and latency before and after 6 months' treatment with olanzapine in 11 patients with schizophrenia. A healthy control group (n = 30) was also studied. Overall, no significant changes, either in amplitude or in latency as measured at Pz and Fz electrodes, were found when comparing the pre- and postolanzapine conditions, despite the overall improvement in positive and negative symptoms. Nevertheless a direct specific association was observed between a P300 amplitude increase with olanzapine and the improvement in negative symptoms. These data would suggest that P300 amplitude reduction in schizophrenia may be relatively independent from clinical state and treatment, thus constituting a trait marker of schizophrenia. Our data also suggest that, in addition to this, some further changes in P300 amplitude might depend on the clinical state of the patients.     

精神分裂症患者事件相关电位研究

目的 :研究以阴性、阳性症状为主的精神分裂症患者的事件相关电位 (ERPs)。　方法 :将 2 2例阴性、 2 7例阳性未服药的精神分裂症患者和 17例正常对照组 ,进行 N1 0 0 、 P2 0 0 、 N2 0 0 、 P30 0 测查。　结果 :阴性组在 Fz,Cz,Pz,T7,T85个点的 P30 0 波幅显著低于和潜伏期明显长于正常对照组 ;阳性组在 Cz,Pz点的 P30 0 波幅低于正常对照组 (P<0 .0 5 )。 P30 0 的波幅与潜伏期在两组患者之间差异有显著性 (P<0 .0 5 ) ;阴性患者 N1 0 0 、N2 0 0 的波幅低于正常对照组 ;相关分析发现 ,阴性分量表分与 Fz的 P30 0波幅显著负相关 (r=— 0 .31,P<0 .0 5 ) ,与 T7、 T8点的潜伏期呈显著正相关 (r=0 .33,r=0 .35 ,P<0 .0 5 )。　结论 :以阳性、阴性症状为主的精神分裂症可能有不同的神经生物学基础。     

P300 deficits are present in young first-episode patients with schizophrenia and not in their healthy young siblings

ObjectiveTo evaluated P300 (P3b) abnormalities in young first episode patients with schizophrenia and their healthy young siblings.MethodsAn auditory oddball paradigm was used to assess P300 in 53 patients, 27 unaffected siblings and 28 healthy controls. Amplitude and latency of the three midline sites (Fz, Cz, and Pz) were compared between patients, siblings, and controls by a mixed-effects regression model.ResultsP300 amplitude was significantly reduced in patients with schizophrenia but not in healthy siblings, when compared to healthy controls. P300 latency did not significantly differ between the three groups.ConclusionsP300 amplitude but not latency was found to be affected in young patients with recent onset schizophrenia. However, P300 amplitude and latency were found not to be affected in healthy unaffected young siblings and, therefore, did not qualify as an endophenotype for schizophrenia.SignificanceThe failure to find the P300 (P3b) abnormality in healthy siblings of patients with schizophrenia is an important finding and should be added to P300 literature.     

不同症状的精神分裂症患者事件相关电位研究

目的研究以不同症状为主的精神分裂症患者的事件相关电位。方法对16例阴性症状为主、19例阳性症状为主、21例混合型未服药的精神分裂症患者和15例正常对照组，进行ERPsN200、P300测查。结果三组精神分裂症患者中P300波幅与正常对照组相比均明显下降，差畀具有显著性（P〈0．05），只有阴性组P300的潜伏期与正常对照组相比明显延长（P〈0．05）；三组精神分裂症患者中T3点P300波幅与T4相比下降更明显（P〈0．05）；相关分析发现，阴性量表分与Fz的P300潜伏期显著正相关（r=0．33，P〈0．05）。结论不同症状为主的精神分裂症可能有不同的神经生物学基础。     

Low frequency subthalamic stimulation and event-related potentials in Parkinson disease

BackgroundHigh frequency (130 Hz) subthalamic Deep-Brain-Stimulation (STN-DBS) optimally improves cardinal motor symptoms in Parkinson disease (PD). Low stimulation frequencies (60–80 Hz) improve axial symptoms in some patients and, according to preliminary evidences, may also have a beneficial effect on the cognitive component of motor planning.ObjectiveTo analyze the configuration of the P300 component of cortical event-related auditory potentials (ERPs), a reliable index of attentive cognitive functions, at different stimulation frequencies in STN-DBS in PD patients.Methods12 PD patients underwent ERPs recordings using a standard oddball auditory paradigm with STN-DBS at 60 Hz, 80 Hz, 130 Hz, and OFF-stimulation, applied in a randomized double-blind sequence. ERPs analysis considered the peak amplitude and latency of the P300 components at midline electrode positions (Fz, Cz, Pz).ResultsP300 latency over Cz and Pz electrodes significantly increased with STN-DBS at 130 Hz compared to OFF-stimulation. P300 latency was also significantly increased, though to a lesser degree, over Pz electrode with stimulation at 80 Hz. No significant P300 latency modifications were detected at 60 Hz stimulation compared to OFF-stimulation condition. P300 amplitude did not change significantly for any of the stimulation conditions tested.ConclusionsLow frequency STN-DBS is associated with minor modifications of P300 latency compared to conventional stimulation at 130 Hz, possibly suggesting that 60 and 80 Hz may have less interference with attentive and cognitive processes in PD patients.     

Button-pressing affects P300 amplitude and scalp topography.

BACKGROUND: Scant and equivocal research exists examining the effects of button-pressing on P300. Button-pressing may decrease P300 latency and amplitude. The melding of motor potentials and P300 may also confound studies of P300 topography, such as studies of temporal scalp-area asymmetries in schizophrenia. METHOD: P300 was measured on button-press and silent-count tasks in control subjects. An estimate of motor activity was constructed from a simple reaction time task, with reaction times matched to the button-press task. The motor estimate was subtracted from the button-press P300 to assess Kok's (1988) additive model. Lastly, lateral P300 from schizophrenia patients was compared with each condition's P300. RESULTS: P300 was smaller and its topography different in the button-pressing task relative to silent-counting. The motor-correction procedure generated a P300 with normal topography. Comparison of the button-press P300 in controls to the silent-count P300 in schizophrenia patients reduced a significant lateral asymmetry to trend level. This asymmetry was significant after the correction procedure. CONCLUSIONS: Button-pressing generates smaller P300 than silent-counting. Also, P300 topography in button-pressing tasks is confounded by motor potentials. The distortion can be corrected with a motor potential estimate. Motor potentials can occlude differences in P300 topography between groups.     

CHANGES IN P300 FOLLOWING TWO YOGA-BASED RELAXATION TECHNIQUES

Cyclic meditation (CM) is a technique that combines “stimulating” and “calming” practices, based on a statement in ancient yoga texts suggesting that such a combination may be especially helpful to reach a state of mental equilibrium. The changes in the peak latency and peak amplitude of P300 auditory event–related potentials were studied before and after the practice of cyclic meditation compared to an equal duration of supine rest in 42 volunteers (group mean age ± SD, 27 ± 6.3 years), from Fz, Cz, and Pz electrode sites referenced to linked earlobes. The sessions were one day apart and the order was alternated. There was reduction in the peak latencies of P300 after cyclic meditation at Fz, Cz, and Pz compared to the “pre” values. A similar trend of reduction in P300 peak latencies at Fz, Cz, and Pz was also observed after supine rest, compared to the respective “pre” values, although the magnitude of change in each case was less after supine rest compared to after cyclic meditation. The P300 peak amplitudes after CM were higher at Fz, Cz, and Pz sites compared to the “pre” values. In contrast, no significant changes were observed in the P300 peak amplitudes at Fz, Cz, and Pz after supine rest compared to the respective “pre” state. The present results support the idea that “cyclic” meditation enhances cognitive processes underlying the generation of the P300.     

Changes in p300 following two yoga-based relaxation techniques

Cyclic meditation (CM) is a technique that combines "stimulating" and "calming" practices, based on a statement in ancient yoga texts suggesting that such a combination may be especially helpful to reach a state of mental equilibrium. The changes in the peak latency and peak amplitude of P300 auditory event-related potentials were studied before and after the practice of cyclic meditation compared to an equal duration of supine rest in 42 volunteers (group mean age +/- SD, 27 +/- 6.3 years), from Fz, Cz, and Pz electrode sites referenced to linked earlobes. The sessions were one day apart and the order was alternated. There was reduction in the peak latencies of P300 after cyclic meditation at Fz, Cz, and Pz compared to the "pre" values. A similar trend of reduction in P300 peak latencies at Fz, Cz, and Pz was also observed after supine rest, compared to the respective "pre" values, although the magnitude of change in each case was less after supine rest compared to after cyclic meditation. The P300 peak amplitudes after CM were higher at Fz, Cz, and Pz sites compared to the "pre" values. In contrast, no significant changes were observed in the P300 peak amplitudes at Fz, Cz, and Pz after supine rest compared to the respective "pre" state. The present results support the idea that "cyclic" meditation enhances cognitive processes underlying the generation of the P300.     

Neurophysiological efficiency in male and female alcoholics

Chronic alcoholics often exhibit impairment in behavioral indicators of cognitive efficiency. However, potential neurophysiological correlates of this deficit are understudied. To examine this function, semantic expectancy was measured by recording the N400 component of the event-related potential (ERP), which is elicited by incongruent semantic information. Abstinent alcoholics, 21-45 days sober (n = 26; 12 males, 14 females), as well as age and education equated community controls (n = 26; 12 males, 14 females), were instructed to read silently 218 sentences ending with either congruent, related/incongruent, or unrelated/incongruent terminal words. Difference waveforms to the terminal word were derived, and amplitude and latency measures of the most negative peak between 300 and 600 ms were obtained. Electrode sites included the midline sites, Fz, Cz, and Pz; the temporal sites T3 and T4; and parietal sites P3 and P4. Significant group effects in amplitude were observed for the difference waveform under the unrelated/incongruent condition at T3, T4, and P4 (P < or = .05). Measures at P3, Pz, Fz, and Cz approached significance (P < or = .15). Although the overall pattern did not change when regression techniques were used to control for age, only the T4 site retained significance (P < or = .05). Across all electrode sites, alcoholics produced reduced N400 amplitudes relative to community controls. Latency was unaffected. There were no group effects for amplitude or latency measures in the related/incongruent condition. These data are consistent with the hypothesis that alcoholics suffer from a subtle deficiency in neurophysiologically based cognitive efficiency which renders them less likely to respond appropriately to irrelevant information.     

Event-related potentials in schizophrenic patients during a degraded stimulus version of the visual continuous performance task

Previous studies of the auditory P300 event-related potential (ERP) have reported smaller amplitudes in chronic schizophrenics but similar consistencies have not been observed with visual P300s. This study examined P300s in symptomatically stable, medicated, chronic schizophrenics (n = 14) and normal controls (n = 14) performing a visual continuous performance task utilizing degraded stimuli to burden encoding processes. Performance analysis found slower response times, fewer target detections and more false alarms in patients than in controls. Analysis of ERPs showed P300 amplitudes of schizophrenics to be significantly smaller than those of controls and, unlike controls, schizophrenics failed to exhibit significant target vs. non-target P300 amplitude differences. Discriminant analysis indicated target and non-target midline (Fz, Cz, Pz) P300 amplitudes together correctly classified all patients and controls. Exploratory topographic analysis indicated that P300 amplitudes were not asymmetrical in patients, as has been observed with auditory P300s, and, unlike the performance measures, the P300s did not correlate with the patient's positive or negative symptom ratings. The implications of these findings are described in relation to attentional disturbances and trait versus state issues in schizophrenics.     

Electrophysiological indices of biased cognitive processing of substance-related cues: a meta-analysis

Several studies indicate that individuals with substance use disorders (SUD) exhibit biases in the cognitive processing of substance-related stimuli. These biases facilitate the detection of substance cues and have been argued to play a causal or perpetuating role in addiction. Two electrophysiological indices of cognitive processing, the P300 and Slow Potential (SP) components of the event-related potential (ERP), are associated with the deployment of attentional resources to motivationally relevant stimuli. In the present meta-analysis P300 (300-800ms) and SP (>800ms) amplitudes are used to investigate whether SUD persons show enhanced cognitive processing of substance cues relative to neutral cues as opposed to control participants. Results indicated the P300 and SP amplitude effect sizes were significantly larger in SUD participants than controls. This result is explained by substance users' motivated attention. Additional stratified moderator analyses revealed that both P300 and SP amplitudes were not moderated by electrode site (Fz vs. Pz), type of substance used (stimulants vs. depressants), substance use status (abstinent vs. non-abstinent), age, gender and task requirements (active vs. passive paradigms).     

The effect of sex differences on event-related potentials in young adults.

Female/male cognitive differences have been studied for some time; however, such differences in Turkish population is unknown. Evoked potentials (EPs) of the brain have been applied as an index of information processing in a wide variety of normal and cognitive impaired subjects. Scalp event-related potentials (ERP) evoked by auditory stimuli were recorded in 20 male and 18 female neurologically and audiologically normal young Turkish subjects of 18-25 years (Av. 20.6) of age. Standard auditory "Oddball" paradigm involving simple discrimination task of concentrating on infrequent (target) stimulus and ignoring frequent (non-target) stimulus was employed. EEG activity was recorded at the Fz, Cz, Pz and Oz electrode sites of the 10-20 system using Ag/AgCl electrodes. Wave forms were collected and averaged off-line by a Pentium 100 computer, which also controlled the stimulus presentation. In general, significant main effects of gender and electrode site on evoked potential components were found. The interpeak amplitudes N1-P2 and N2-P3 were higher in the male subjects than in the female subjects at Cz. N2-P3 were higher in the male subjects than in the female subjects at Oz. The latencies of N1, P2, N2, P3 components were not different between both sex. For both sexes we found that N1-P2 amplitude was higher at Fz and Cz than Pz and Oz. N2-P3 amplitude was higher at Fz than Oz for only female subject. In male subjects, latency of N2 was longer at Fz than Oz. There were no significant differences in the latencies of N1, P2, and P3 components between electrode sites in both sexes. We suggest that ERP components could be affected by sex, electrode site, and cognitive performance.     

Clinical and neuropsychological correlates of the P300 in schizophrenia

We investigated the relationship between the P300, neuropsychological test performance and symptomatology in recent-onset schizophrenic patients (n = 45) to gain insight into underlying mechanisms of abnormal P300 in schizophrenia. The P300 was recorded in two sessions with an intermission of five minutes, at the midline frontal, central and parietal electrode site. P300 amplitude and latency were compared with those obtained in 25 controls. Twenty patients were treated with olanzapine and 19 patients with risperidone. P300 amplitude was smaller and latency longer in patients than in controls. In the patient group, parietal P300 amplitude reduction was related to poorer performance on neuropsychological tests of memory. Frontal P300 amplitude reduction was related to impaired selective attention. In patients with negative symptomatology, P300 amplitude was reduced in the second P300 session compared with the first. Patients on risperidone demonstrated a smaller parietal P300 amplitude than patients using olanzapine. Reduced parietal P300 amplitude could signify a dysfunction in the continuous memory updating of current events. Negative symptomatology may be associated with a time dependent decrease in neuronal firing, as indicated by reduced P300 amplitude in the second P300 session.     

草酸艾司西酞普兰对抑郁症患者事件相关电位P300的影响

目的:探讨草酸艾司西酞普兰对抑郁症患者的事件相关电位P300影响。方法:随机将年龄在18～65岁之间符合中国精神障碍分类与诊断标准第3版抑郁症诊断标准患者30例作为研究组,选择30例性别年龄健康者作为对照组。研究组予草酸艾司西酞普兰治疗。两组分别予听觉P300检测,比较P300潜伏期及波幅的差异。结果:研究组Fz、Pz点潜伏期分别为(319±23)ms、(315±20)ms均比对照组分别为(300±22)ms、(299±21)ms延长,研究组Fz、Cz、Pz点分别为(2.5±1.8)μV、(2.6±2.4)μV、(2.5±3.3)μV波幅均比对照组分别为(3.8±2.0)μV、(3.7±1.9)μV、(4.1±3.0)μV降低(P<0.05或P<0.01)。治疗8周后,研究组Fz、Pz点潜伏期分别为(301±19)ms、(305±19)ms]明显缩短,Fz、Cz、Pz点分别为(3.5±1.8)μV、(3.7±2.1)μV、(3.6±3.5)μV波幅明显升高(P<0.05)。结论:抑郁症患者存在P300异常,草酸艾司西酞普兰具有改善这种异常现象的作用。     

事件相关电位诊断动脉瘤性蛛网膜下腔出血后认知功能障碍的研究

目的 评价事件相关电位N200和P300评估动脉瘤性蛛网膜下腔出血（aneurysmal subarachnoid hemorrhage,aSAH）患者早期认知障碍的价值。 方法 连续纳入2013年10月-2014年12月于首都医科大学附属北京天坛医院住院治疗的aSAH患者, 按照入院14±3 d是否存在认知障碍分为aSAH认知障碍组和aSAH无认知障碍组,同时纳入年龄、性 别相匹配的正常人群作为对照组。所有入组患者完成MMSE、MoCA量表评定及脑电图事件相关电位 N200和P300潜伏期的测定[额中线（frontal midline,Fz）、中央中线（central midline,Cz）、顶中线（parietal midline,Pz）三个部位]。比较对照组、aSAH认知障碍组和aSAH无认知障碍组间N200及P300潜伏期的 差异。分析N200和P300诊断aSAH患者认知障碍的敏感性和特异性。另外,通过单因素和多因素分析, 明确aSAH患者发生早期认知障碍的独立危险因素。 结果 共入组62例aSAH患者,存在认知功能障碍者45例（72.6%）,无认知障碍者17例（27.4%）;对 照组30例患者。aSAH无认知障碍组和aSAH认知障碍组Cz、Pz和Fz的P300潜伏期均长于正常对照组, Cz和Pz的N200潜伏期长于正常对照组,aSAH认知障碍组Fz的N200潜伏期长于正常对照组,差异有统 计学意义;与aSAH无认知障碍组相比,aSAH认知障碍组Cz、Pz和Fz的P300及N200潜伏期均延长,差 异有统计学意义。事件相关电位N200潜伏期分界值为257.0～261.0 ms时,诊断认知障碍的敏感度为 67.1%～79.4%,特异度为74.2%～81.5%;事件相关电位P300潜伏期分界值为347.0～349.5 ms时,诊 断认知障碍的敏感度为88.1%～94.0%,特异度为78.9%～82.1%。多因素分析结果显示,低受教育年 限（OR 1.19,95%CI 1.02～2.15,P =0.037）及Hunt-Hess分级3级（OR 1.65,95%CI 1.05～1.92,P =0.013） 是aSAH患者出现早期认知障碍的独立危险因素。 结论 事件相关电位N200和P300可以作为判断aSAH患者早期认知功能障碍的一种有用的、客观的 检查工具。     

Left hemisphere specialization for rapid temporal processing: a study with auditory 40 Hz steady-state responses.

OBJECTIVE: To investigate rapid temporal processing in the auditory cortex by using auditory 40 Hz steady-state responses (SSRs). METHODS: A 40 Hz tone-burst at 500 Hz spectral frequency was presented monaurally to record SSRs in 10 normal subjects. The recording electrodes were placed over C1, C2, C3, C4, C5, C6, T3, T4, Fz, Cz and Pz, referring to an electrode at the 7th cervical spinous process. For comparison, unstimulated SSRs were recorded. A total of 200 responses of 1s epoch were averaged and subjected to discrete fast Fourier transforms to yield the amplitude and phase of the 40 Hz component. The coherence (Coh) values of the 40 Hz component between homologous electrodes were also calculated. RESULTS: At the temporal electrodes contralateral to the stimulated ear, the amplitude was significantly larger and its phase was significantly smaller than those of the ipsilateral side. The interhemispheric Coh between T3 and T4 in response to right ear stimulation was significantly greater than those of left ear stimulation or the unstimulated condition. CONCLUSIONS: Our results suggest that 40 Hz auditory information is predominantly processed in the left auditory cortex, interacting with the right hemisphere. This finding is consistent with the fact that the left auditory cortex plays an important role in rapid temporal processing. SIGNIFICANCE: Auditory 40 Hz SSRs with Coh analysis are useful for investigating the left hemisphere specialization for rapid temporal processing.     

康复期男性海洛因依赖者注意力与听觉P300的研究

目的探讨处于康复期的海洛因依赖者注意力与听觉P300的特点以及二者的关系。方法以数字划销测验（NCT）评估38例康复期的男性海洛因依赖者（MPHD）和14例健康对照的注意力，同时以脑诱发电位仪检测康复期MPHD及健康对照前额区（Fz）、中央区（Cz）及项区（Pz）听觉P300。结果康复期MPHDNCTI阶段、Ⅱ阶段、Ⅲ阶段、V阶段净分及总净分均显著低于对照组（P〈0．05或P〈0．01）；Cz点AEP—P300波幅显著低于健康对照组（P〈0．05）。MPHDFz、Cz点AEP-P300波幅与净分V呈正相关（P〈0．01），在Pz点AEP—P300波幅与净分Ⅲ呈正相关（P〈0．05）；在Cz点AEP—P300潜伏期与净分工及净分Ⅲ呈正相关（P〈0．05）。结论康复期MPHD存在明显的注意力损害与皮质功能的紊乱，AEP—P300可在一定程度上反映海洛因依赖者注意力损害的程度。