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.     

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。     

Abnormalities of auditory event-related potentials in students with high scores on the Schizotypal Personality Questionnaire

Some auditory event-related potential (ERP) abnormalities characterize both patients with schizophrenia and subjects with schizotypal personality disorder. It was therefore hypothesized that subjects from the community with schizotypal traits might also present ERP abnormalities. In this study, we compared auditory ERP latencies and amplitudes in 13 subjects with high (H-SPQ) and 12 subjects with low (L-SPQ) scores on the Schizotypal Personality Questionnaire (SPQ), selected from 198 Tunisian students. Auditory ERPs were recorded at Fz, Cz, and Pz, with a standard oddball paradigm. Smaller P300 amplitudes and delayed P300 latencies were found in H-SPQ compared with L-SPQ participants. Confirming previous reports, our results suggest that reduced P300 amplitudes and delayed P300 latencies may be considered as vulnerability markers of the schizophrenia spectrum in nonclinical subjects from the community.     

有暴力行为青少年事件相关电位N400的对照研究

目的：探讨有暴力行为青少年和正常青少年语言认知功能神经电生理的特点。方法：对我市未成年犯管教所服教的有暴力犯罪行为记录的51例男性青少年（暴力组）和40名既往无暴力犯罪行为记录的普通中学生（正常对照组）分别进行脑诱发电位N400的测定。结果：与对照组比较,暴力组N400Fz、Cz、Pz潜伏期明显延长（F=6.59、6.51、7.16,P均=0.00）,波幅显著降低（F=4.49、4.14、2.15,P〈0.05或P〈0.01）。结论：有暴力行为的男性青少年语言认知功能N400异常,提示可能存在语言认知功能的受损。     

P300 event-related potential in epileptic children and adolescents

P300 is a manifestation of activity in a limited capacity system "whose use in the service of different tasks is under relative control by instruction". It is accepted as an objective correlate of mental processing involved in the allocation of attentional resources when immediate memory is engaged. The aim of this study was to evaluate cognitive function in epileptic children and adolescents. We applied the "auditory oddball" paradigm to elicit event-related potentials (ERPs) according to the IFCN recommendation standards. ERPs were studied in fifteen patients with generalized epileptic seizures at matched age (8-18 years) (mean 13.8 +/- 2.4 y). 50 neurologically normal children were used as a control group. ERP were averaged with a Multiliner (Toennies, Germany) equipment. The method included two different tones for frequent and for rare stimuli generated at random. The tones were presented binaurally through headphones. ERPs were recorded at Fz, Cz and Pz according to the International 10-20 system. ERPs for target and non-target stimuli were averaged separately. The major positive peak between 250 and 500 ms for the rare tones was regarded as the cognitive evoked potential (P300). Latency values were obtained from the intersection of extrapolated lines from the ascending and descending slopes of each peak. The latencies of the N1, P2, N2 and P300 waves were determined for each subject, as well as peak to peak amplitudes of N1-P2, P2-N2, N2-P300. Auditory event related potential may be helpful procedures used in objective evaluation of cognitive function in patients with epilepsy.     

Flunitrazepam-induced changes in neurophysiological,behavioural, and subjective measures used to assess sedation

INTRODUCTION: Certain features of event-related potentials (ERPs), electroencephalographic (EEG), and behavioural measures vary with differing states of alertness and/or sedation. PURPOSE: This study was conducted to investigate changes in several measures usually viewed as reflecting states of sedation/sleepiness associated with the use of a range of doses of the hypnotic benzodiazepine (BZD) flunitrazepam (FNZ). METHODS: This was a double blind, independent group design study of the effects of acute oral doses of FNZ in young healthy volunteers. Forty-eight subjects were randomly allocated to one of four groups-FNZ (0.6, 0.8, and 1.0 mg) and placebo (PLAC)-and tested prior to treatment and then in a posttreatment session close to the theoretical peak plasma concentration. ERP latencies and amplitudes were measured at midfrontal (Fz), midcentral (Cz), and midparietal (Pz) using a standard auditory oddball paradigm. EEG changes were assessed at Pz. Behavioural measures included the digit-symbol substitution test (DSST), a cancellation task (CT), and subjective ratings of alertness and attentiveness by the subjects (SUB) and the experimenter (EXP). RESULTS: FNZ led to psychomotor impairments and decreased alertness and attention; these effects were consistent with previous findings. A progressive, dose-related increase in P3 latency occurred in Fz, Cz, and Pz, and there was an increase in N1 (Fz, Cz) and N2 (Fz). N2-P3 amplitude decreased in Fz. EEG power bands beta 1 increased for the two highest doses, but no significant differences were noted in theta, delta, and alpha bands. P3 latencies, experimenter-rated levels of alertness, and DSST scores differentiated all three doses of FNZ from PLAC. CONCLUSION: The most sensitive measures used were P3 latencies of the ERPs (which varied with FNZ dose), DSST, and the experimenter-rated levels of alertness. However, we found no evidence for the assumption that one single phenomenon was reflected in all measures and different mechanisms were probably involved. Further experiments will be needed for more in-depth probing of the finer mechanisms underlying sedation/sleepiness and how they affect behavioural and eletrophysiological measures of the central nervous system (CNS) function.     

The role of event related potentials in evaluation of subclinical cognitive dysfunction in epileptic patients

BACKGROUND/AIM: Cognitive dysfunction in epileptic patients may develop due to the neurophysiological changes related to seizures or antiepileptic drugs. The aim of this study was to evaluate the cognitive dysfunction in epileptic patients under antiepileptic drug therapy by the aid of event related potentials. METHOD: P300 latencies were obtained from Fz, Cz and Pz electrod positions from both epileptic patients (n=40) and age and sex matched control group (n=40). Epileptic patients were classified either idiopathic primary generalized (IPGE) (n=9) or secondary generalized epilepsy (SGE) (n=31) based on the ILAE classification. The effect of epilepsy type, treatment types (monotherapy/polytherapy), daily dosages and serum levels of antiepileptic drugs, age at onset and EEG abnormalities on P300 latencies were studied. RESULTS: P300 latencies were longer in the epileptics when compared to controls (P < 0.05). Besides, our results pointed out that P300 latencies were longer in IPGE when compared to SGE (P < 0.05). No statistically significant difference was determined between ERP parameters neither in monotherapy nor in polytherapy groups (p > 0.05). Antiepileptic drug subgroups revealed variable effects on ERP latencies. CONCLUSION: We believe P300 latencies may have an important role in the evaluation of subclinical cognitive dysfunction in epileptic patients treated with antiepileptic drugs.     

康复期男性海洛因依赖患者认知功能与视觉诱发电位P300的关系

目的 探讨康复期男性海洛因依赖患者(MPHD)神经心理学测验成绩与视觉诱发电位P300(VEP-P300)的关系.方法 采用韦氏记忆量表(WMS)、威斯康星卡片分类测验一改良版(M-WCST),对38例康复期MPHD(MPHD组)及14名健康对照(对照组)进行神经心理学评估,并于1周内检测受试者前额区(Fz)、中央区(Cz)及顶区(Pz)的VEP-P300.结果 (1)M-WCST评分:MPHD组卡片分类正确数、正确分类数、随机错误数均少于对照组(P＜0.01),错误数和持续错误数多于对照组(均P＜0.01).(2)WMS评分:除数字顺序累加因子,MPHD组的记忆商数(MQ)及各因子分均低于对照组(P＜0.05～P＜0.01).(3)VEP-P300检测:MPHD组与对照组各指标的差异无统计学意义(P＞0.05).(4)Pearson相关分析:在Fz点,波幅与WMS数字顺序1-100呈正相关(r=0.321),潜伏期与数字顺序1-100(r=-0.325)、图片回忆呈负相关(r=-0.449),均P＜0.05～0.01.在Cz点,潜伏期与M-WCST分类正确数(r=-0.388)、数字顺序1-100(r=-0.386)呈负相关,与分类错误总数呈正相关(r=0.388),均P＜0.05.在Pz点,波幅与数字顺序1-100(r=0.357)、数字顺序100-1(r=0.374)、触觉记忆(r=0.370)、MQ(r=0.322)呈正相关,均P＜0.05;潜伏期与M-WCST分类正确数(r=-0.377)、图片回忆(r=-0.364)呈负相关,与M-WCST分类错误总数呈正相关(r=0.377),均P＜0.05.结论 康复期的MPHD仍存在明显的认知功能损害,VEP-P300与神经心理学测验成绩存在较为密切的关系.     

Contribution of auditory P300 test to the diagnosis of mild cognitive impairment in Parkinson’s disease

Abnormalities in auditory P300 test have been observed in patients with Parkinson’s disease (PD). We aimed to investigate whether or not additional electrophysiological tests assist in making the clinical diagnosis of mild cognitive impairment in Parkinson’s disease (PD-MCI), and we evaluated P300 changes in patients with non-demented PD and analyzed the correlation between the cognitive features and P300 changes. Twenty patients with PD who had been diagnosed with mild cognitive impairment (PD-MCI group) according to the Movement Disorder Society (MDS) 2012 PD-MCI level II criteria, 21 patients with PD without cognitive impairment (PD-Normal group), and 20 control subjects (control group) who were neurologically normal were examined by the standard auditory oddball paradigm. The N100, P200, N200, and P300 latencies and N100-P200, P200-N200, and N200-P300 amplitudes were measured and analyzed. P300 latencies recorded from Fz, Cz, and Pz and N200 latency recorded from Fz were significantly longer in the PD-MCI group than in the PD-Normal and the control group (respectively p < 0.001, p = 0.041). P300 amplitude recorded from Fz was significantly lower in PD-MCI group than those in the other groups (p = 0.038). While P300 was obtained in all patients in the PD-Normal and the control group, it was lost in 35% of PD-MCI patients. The results show that P300 provides a diagnostic tool for detecting PDMCI. We suggest that P300 prolongation and loss of P300 potential could be used as supportive parameter in the diagnosis of PD-MCI.     

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。     

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.     

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.     

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。     

EFFECTS OF ESTRADIOL ON COGNITION EVALUATED WITH P300 IN IN VITRO FERTILIZATION PATIENTS

The authors planned to show the effect of high-level estrogen on cognitive functions, using P300 in the in-vitro fertilization (IVF) population. Eighteen IVF patients (mean age 31.39 ± 5.01) without any detectable cognitive disorder were enrolled in this study. The authors measured N100, P200, N200, P300 latencies and amplitudes at Cz and Fz recordings during the lowest and highest blood estradiol levels. P300 amplitudes were significantly reduced during the highest level of estradiol compared to the lowest level both at Fz and Cz recordings. The other subcomponents of P300 were not significantly influenced by blood estradiol levels. The results revealed a decline in the ability of task relevance and state of arousal when the estradiol level was the highest in the IVF patients.     

Effects of estradiol on cognition evaluated with p300 in in vitro fertilization patients

The authors planned to show the effect of high-level estrogen on cognitive functions, using P300 in the in-vitro fertilization (IVF) population. Eighteen IVF patients (mean age 31.39 +/- 5.01) without any detectable cognitive disorder were enrolled in this study. The authors measured N100, P200, N200, P300 latencies and amplitudes at Cz and Fz recordings during the lowest and highest blood estradiol levels. P300 amplitudes were significantly reduced during the highest level of estradiol compared to the lowest level both at Fz and Cz recordings. The other subcomponents of P300 were not significantly influenced by blood estradiol levels. The results revealed a decline in the ability of task relevance and state of arousal when the estradiol level was the highest in the IVF patients.     

P300 asymmetry in schizophrenia: a meta-analysis

P300 event-related brain potential (ERP) amplitude is smaller in patients with schizophrenia compared to unaffected controls, but whether left temporal component amplitude is also smaller is debated. The present study employed meta-analytical methods to quantitatively assess previous P300 schizophrenia asymmetry findings. All P300 articles on schizophrenia using an auditory oddball paradigm published before January 2000 were obtained by comprehensive literature searches and cross-referencing for related articles. A total of 19 original articles reporting complete midline electrode data and 11 articles reporting lateral asymmetry electrode data were reviewed, which included different independent conditions that yielded 50 independent data sets. P300 amplitude differences between patients with schizophrenia and control subjects from the midline electrodes yielded effect sizes that differed among recording sites, such that Fz was significantly smaller than Pz, with Cz effect sizes smaller than Pz but larger than Fz. Comparison of P300 amplitude from the lateral data for the T3 and T4 electrodes found no reliable effect size difference when these electrodes were analyzed separately. However, comparison of P300 amplitude effect sizes from the TCP1 was significantly larger than that from the TCP2 when these electrodes were analyzed separately. P300 amplitude is smaller overall in patients with schizophrenia compared to control subjects and differs in its effect size topography across the midline and temporal electrode sites, with the strongest effect sizes obtained for the Pz midline and TCP1 lateral electrodes.     

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。     

Reappraisal of filter effects on P300 voltage and latency.

The selection of which high-pass filter cutoff to use in P300 studies continues to be a serious methodological consideration. To determine whether there was an optimal range of bandpass widths-a range in which P300 voltage and latency would not show statistically significant differences-the authors recorded P300 responses to the auditory "oddball" paradigm from Cz and Pz electrodes in a group of eight healthy males. The authors used high-pass filter cutoffs of 0.01, 0.1, 0.3, and 1.0 Hz with low-pass filter cutoffs of 30 and 100 Hz and measured both P300 peak voltages and P300 integrated mean voltages at 12 bandpass settings. There were statistically significant differences in 7 out of 12 bandpass comparisons for P300 peak voltages and in 7 out of 12 bandwidth comparisons for P300 integrated mean voltages. For P300 latencies, there were statistically significant differences in 9 out of 12 bandwidth comparisons. Based on these results, the best recommendation, therefore, is that the high-pass filter be set no higher than 0.3 Hz.     

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.     

Latency variability of the components of auditory event-related potentials to infrequent stimuli in aging, Alzheimer-type dementia, and depression

Auditory event-related potentials (ERPs) were investigated in 15 demented (12 presumed Alzheimer's, 3 cerebrovascular), 8 depressed, and 15 normal older, and 12 normal young, subjects. Both latencies from conventional averages and latency variability measures from single trials were derived for the N100, P200, N200, and P300 components of the ERP recorded from Fz, Cz and Pz scalp placements in a task requiring detection of an infrequent target tone among a series of frequent non-target tones. The P300 component most consistently separated the groups. Demented subjects had longer P300 latencies and greater P300 latency variability than both control groups and the depressed group. Age differences were observed for P300 latency, but not for P300 latency variability. Amplitudes were not significantly different among the groups. Reaction times (RTs) to the targets were longest for the demented subjects and shortest for the young controls, with the depressed and normal older control groups falling in between. Correlations between RT and P300 latency from single trials did not differentiate the groups. Using regression analysis to evaluate the deviation of P300 latency and latency variability for the patients from the predicted values for normal controls, no misclassifications of depressed patients occurred, but only 27% of the demented individuals were correctly classified using P300 variability, and 13% using P300 latency. These findings indicate that ERP measures using the 'oddball' target detection paradigm were useful in describing group differences, but were not sufficiently sensitive to be used in differentiating demented persons on an individual basis for clinical diagnosis.