Fast stimulus sequences improve the efficiency of event-related potential P300 recordings

The P300 is an easily recorded component of the event-related potential (ERP). Yet, it is desirable to reduce the recording duration, for instance in patient examinations. A limiting factor is the time between stimuli that is necessary for the ERP to return to baseline. We explored whether this time could be reduced, despite an overlap of responses to successive stimuli, by presenting visual stimuli at a fast rate of 4.7s(-1)using a standard oddball paradigm. Rare stimuli occurred at a probability of 14%. The P300 was isolated by subtracting the responses to the frequent stimuli from those to the rare stimuli, thereby eliminating the influence of response overlap. We compared the efficiency of fast stimulation to that of conventionally slow stimulation by assessing the signal-to-noise ratio of the P300 amplitude. Two presentation durations of individual stimuli, namely 53ms and 93ms, were tested. Not unexpectedly, P300 amplitudes were smaller for the fast sequence. However, the signal-to-noise ratio improved significantly by more than 50% due to the larger number of trials within a given time interval. When targeting a given signal-to-noise ratio, fast stimulation allows for a reduction in recording time of around 35%. Median peak times were 16-56ms shorter for the fast stimulus sequence. Topography was comparable for fast and slow stimulation, suggesting a similar functional composition of the respective responses. Fast stimulation may thus be used to replace less efficient slow stimulation schemes in clinical diagnosis and for certain experimental questions.     

老年期焦虑抑郁患者事件相关电位P300特征

目的：探讨老年期焦虑抑郁共病患者认知功能的事件相关电位P300特征。方法：对60例老年抑郁症患者（以伴有焦虑者为共病组25例,单纯抑郁症者为抑郁症组35例）及60名性别、年龄匹配的正常老年人（对照组）进行听觉诱发的事件相关电位P300检测。同时应用汉密尔顿抑郁量表（HAMD）、汉密尔顿焦虑量表（HAMA）及老年认知功能量表（SECF）分别评价患者组抑郁、焦虑情绪及认知功能。结果：患者组P2、N2、P3潜伏期及反应时间比对照组明显延长,P2、P3波幅明显降低;共病组N2、P3波幅比抑郁症组明显降低,P3潜伏期明显延长。患者组HAMD、HAMA总分与P300各指标无相关,而SECF总分与N2、P2、P3潜伏期呈显著负相关。结论：P300对老年期抑郁症早期认知功能损害评定具有一定的价值,共病组患者认知功能损害程度大于抑郁症组。     

The P300 wave of the human event-related potential.

The P300 wave is a positive deflection in the human event-related potential. It is most commonly elicited in an "oddball" paradigm when a subject detects an occasional "target" stimulus in a regular train of standard stimuli. The P300 wave only occurs if the subject is actively engaged in the task of detecting the targets. Its amplitude varies with the improbability of the targets. Its latency varies with the difficulty of discriminating the target stimulus from the standard stimuli. A typical peak latency when a young adult subject makes a simple discrimination is 300 ms. In patients with decreased cognitive ability, the P300 is smaller and later than in age-matched normal subjects. The intracerebral origin of the P300 wave is not known and its role in cognition not clearly understood. The P300 may have multiple intracerebral generators, with the hippocampus and various association areas of the neocortex all contributing to the scalp-recorded potential. The P300 wave may represent the transfer of information to consciousness, a process that involves many different regions of the brain.     

Inhibition, response mode, and stimulus probability: a comparative event-related potential study.

OBJECTIVES: In the present study, effects of response mode (finger movement or counting) and stimulus probability on inhibitory processes were studied.METHODS: Electroencephalographic activity was registered in a visual go/nogo paradigm. Subjects either responded manually to go stimuli or counted silently the occurrence of each go stimulus in different conditions. In both response mode conditions, response probability was varied.RESULTS: For finger movement and counting, similar N2 and P3 go/nogo effects were found. The amplitude of the nogo N2 and nogo P3 varied as a negative function of nogo stimulus probability. The go P3 varied as a negative function of go stimulus probability. In the manual condition, however, the descending flank of the go N2 at anterior electrode sites was more negative in the 0.50go and 0.75go probability trials than in the 0.25go probability trials.CONCLUSIONS: The results of the present study confirm the hypothesis that differences between go and nogo event-related potentials are not dependent on overt movement-related potentials. It could be speculated that the probability effect on the N2 amplitude in go trials in the manual condition has to be explained in terms of a modulation of the strength of motoric preparation processes varying as a positive function of the probability of the go stimulus.     

P300 event-related brain potential and personality in depression.

P300 is an event-related brain potential (ERP) particularly interesting to the study of cognitive processes in normal subjects and in psychopathology. P300 has been applied in depression with controversial results. A major source for these controversial results could result from the diversity of depressed patients included in the different studies. Supporting this assumption, impulsivity, blunted affect, suicidal behavior and psychotic features significantly influence P300 amplitude. However, no data are available on the possible influences of the personality of depressed patients on P300. Since personality is related to P300 in normal subjects, the aim of the present study is to investigate the relationship between ERPs (P200, N200, and P300) and the Temperament and Character Inventory (TCI) in 54 depressed patients. The main results of the study concern the absence of major correlations between personality dimensions as assessed by the TCI and ERP parameters among depressed patients. Only weak partial positive correlations relate N200 latency with harm avoidance, and P300 amplitude (Pz) with the self-directedness dimension. N200 amplitude is also negatively correlated to persistence. However, the preliminary nature of the presented results with respect to the weak statistical significance should be underlined.     

老年期抑郁症患者事件相关电位P300特征

目的：探讨有无自杀行为的老年期抑郁症患者认知功能的事件相关电位P300特征。方法：对60例老年期抑郁症患者（有自杀行为者20例,无自杀行为者40例）及60例性别、年龄匹配的正常老年人为对照,进行听觉诱发的事件相关电位P300检测。同时应用汉密尔顿抑郁量表（HAND）及老年认知功能量表（SECF）分别评价抑郁症组抑郁情绪及认知功能。结果：抑郁症组与对照组相比,P2、N2、P3潜伏期明显延长,P2、P3波幅明显降低;有自杀行为组N2、P3波幅比无自杀行为组明显降低。抑郁症组HAMD总分与P300各指标无相关,SECF总分与N2、P2、P3潜伏期显著负相关。结论：P300对老年期抑郁症患者早期认知功能损害评定具有一定价值,有、无自杀行为的老年期抑郁症患者认知功能损害不同。     

精神分裂症患者事件相关电位相关性研究

目的：探讨精神分裂症患者事件相关电位P300的特点及事件相关电位与阴性、阳性症状的相关性。方法：对28例精神分裂症患者及21名健康志愿者进行事件相关电位P300的检测。结果：两组靶刺激时P300的N2、P3潜伏期和P2、P3波幅有显著差异。结论：提示事件相关电位P300在协助精神分裂症的诊断、分型及推测预后方面有一定意义。     

Effects of etizolam and ethyl loflazepate on the P300 event-related potential in healthy subjects

Background

Benzodiazepines carry the risk of inducing cognitive impairments, which may go unnoticed while profoundly disturbing social activity. Furthermore, these impairments are partly associated with the elimination half-life (EH) of the substance from the body. The object of the present study was to examine the effects of etizolam and ethyl loflazepate, with EHs of 6 h and 122 h, respectively, on information processing in healthy subjects.

Methods

Healthy people were administered etizolam and ethyl loflazepate acutely and subchronically (14 days). The auditory P300 event-related potential and the neuropsychological batteries described below were employed to assess the effects of drugs on cognition. The P300 event-related potential was recorded before and after drug treatments. The digit symbol test, trail making test, digit span test and verbal paired associates test were administered to examine mental slowing and memory functioning.

Results

Acute administration of drugs caused prolongation in P300 latency and reduction in P300 amplitude. Etizolam caused a statistically significant prolongation in P300 latency compared to ethyl loflazepate. Furthermore, subchronic administration of etizolam, but not ethyl loflazepate, still caused a weak prolongation in P300 latency. In contrast, neuropsychological tests showed no difference.

Conclusions

The results indicate that acute administration of ethyl loflazepate induces less effect on P300 latency than etizolam.     

Cerebral networks linked to the event-related potential P300

P300 is an event-related potential that is elicited by an oddball paradigm. In several neuropsychiatric diseases, differences in latencies and amplitude compared to healthy subjects have been reported. Because of its clinical significance, several investigations have tried to elucidate the intracranial origins of the P300 component. In the present study we could demonstrate a network of P300 generators. Investigated were 15 healthy subjects with an acoustical oddball paradigm within a fMRI block design, which enabled us to exclude attention or acoustical processing effects. The inferior and middle frontal, superior temporal, lower parietal cortex, the insula and the anterior cingulum were significantly activated symmetrical in both hemispheres.     

Effects of simulated high altitude on event-related potential (P300) and auditory brain-stem responses.

OBJECTIVE: This study investigated the effect of hyobaric hypoxia on cognitive function. METHODS: We recorded the auditory brain-stem response (ABR) and auditory-evoked event-related potentials (ERP) in 7 male subjects during a rapid ascent to a simulated 4500 m altitude from their acclimatized altitude of 610 m. The amplitude and latency of each component of ABR and of ERP were assessed. RESULTS: Compared with the values at 610 m, at 4500 m the latencies of both waves I and V of ABR significantly increased, with no change in I-V interpeak latency; and the amplitude of wave I decreased, with no change in the amplitude of wave V. The increase in altitude affected neither the amplitude nor the latency of N100. The P300 latency was prolonged significantly after exposure to hypobaric-hypoxic conditions for 2h, with no significant change in amplitude. At 4500 m, the P300 latency returned to the baseline value after oxygen was inhaled. CONCLUSIONS: Our results suggest it is possible to boost cognitive processing by supplying oxygen even when auditory stimulus intensity decreases under hypobaric and hypoxic conditions, and that P300 latency is affected by hypoxic more than hypobaric conditions. SIGNIFICANCE: This study demonstrated that each component of ABR and the latency of both N100 and P300 are important to record when the effects of hypobaric hypoxia on cognitive function are investigated.     

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.     

Alcoholism risk, tobacco smoking, and P300 event-related potential.

OBJECTIVE: The P300 event-related potential (ERP) is sometimes larger for individuals at low- compared to high-risk for alcoholism. These effects are inconsistent, and how P300 is affected by tobacco smoking in the context of alcoholism risk is unknown. The present study used P300 to examine the inter-relationship between alcoholism heritability and smoking status. METHODS: P300 was elicited with a visual discrimination task from young adults at low- and high-risk for alcoholism. Half of the subjects in each risk category reported that they did not smoke cigarettes, and the other half reported that they smoked regularly, with equal numbers of male and female subjects assessed. ERPs were recorded, and subjects were instructed to respond only to an infrequently presented target stimulus that occurred in a series of standard and distracter stimuli. RESULTS: P300 amplitude from the target stimuli was larger for the low-risk compared to high-risk subjects overall. However, smoking status demonstrated even stronger effects, with non-smokers producing consistently larger component amplitudes than smokers and accounting for more variance than alcoholism risk. These group factors also significantly affected P300 scalp topography. No reliable alcoholism risk or smoking group effects were obtained for the ERPs from the other stimuli. CONCLUSIONS: The findings suggest that P300 measures of alcoholism risk in young adults are moderated by smoking status. Theoretical implications are discussed.     

癫痫患者智能状况与事件相关电位P300的研究

目的探讨癫痫患者智能状况、事件相关电位P300(ERP P300)的特点及ERP P300对癫痫患者智能状况的评定价值.方法对40例癫痫患者进行智商及ERP P300测定.结果40例癫痫患者中总智商FIQ≤89者14例,占35%;P300异常者16例,占40%.癫痫智能障碍组的VIQ、PIQ、FIQ、P300 PL分别与智能正常组及正常对照组比较,均具有显著性差异(P<0.01).且癫痫患者P300PL与VIQ、PIQ、FIQ呈负相关.结论癫痫患者易发生智能损害,且智能损害无选择性.智力量表和ERPP300二种检测方法对评判癫痫患者智能障碍具有良好的一致性,而ERP P300能更早期、更客观、快捷、准确地评价癫痫患者智能状况.     

P300 event-related potential and serotonin-1A activity in depression.

The identification of the brain structures and neurotransmitters responsible for the generation and/or modulation of P300 could lead to important clinical implications. Since serotonin disturbances seem to play a critical role in depression, the aim of the study was to assess the possible relationships between the P300 event-related brain potential and serotonergic activity in depression. The study was conducted among 45 major depressive inpatients, and serotonergic activity was assessed by prolactin (PRL) response to flesinoxan (a 5-HT1A agonist). Results showed a significant negative correlation between P300 amplitude and PRL response to flesinoxan (r = -0.40, P = 0.007 at Cz; r = -0.47, P = 0.001 at Pz). In contrast, both P300 latency and reaction time were not related to endocrine response. This study supports a role for serotonin-1A in the neurobiological modulation of P300 amplitude.     

Dipolar source modeling of the P300 event-related potential after somatosensory stimulation.

The cerebral generators of the P300 potential evoked by somatosensory stimuli were investigated. Event-related potentials elicited by an oddball paradigm were recorded in 15 healthy subjects by 19 scalp electrodes. Nontarget and target electric stimuli were delivered on the anterior surface of the left elbow and of the wrist, respectively. Target traces showed an N140 potential followed by a widely distributed P300 response. Dipolar source modeling of target traces resulted in a six-dipole model. In the earlier latency range (up to 200 ms), one dipole in the contralateral perirolandic region and two dipoles in the parasylvian cortex of both hemispheres were activated. Two dipolar sources located bilaterally in the medial temporal region (MTR) showed their maximal activity at the P300 latency. Finally, a dipole in the contralateral frontal lobe was activated both at the latency of the N140 response and after 200 ms. It was found that two symmetrical MTR sources and a frontal dipole contributed to P300 generation.     

P300 event-related potential amplitude and impulsivity in cocaine-dependent subjects

Previous studies report reduced amplitude of the P300 event-related potential in cocaine-dependent individuals. Cocaine dependence is also associated with increased impulsivity, possibly due to deficits in cognitive function that are associated with reduced P300 amplitude. In the current study, the relationship between cocaine dependence, impulsivity, and P300 amplitude were examined. An auditory oddball event-related potential task along with self-report (Barratt Impulsiveness Scale version 11) and behavioral laboratory (Immediate and Delayed Memory Task) measures of impulsivity were assessed in healthy controls (n = 14) and subjects who met DSM-IV criteria for current cocaine dependence (n = 17). P300 amplitude was reduced and self-reported and behavioral laboratory impulsivity scores were elevated among the cocaine-dependent group compared to controls. There was a positive correlation between the questionnaire and behavioral laboratory measures of impulsivity, and a negative correlation between impulsivity measures and P300 amplitude. The correlation between self-reported impulsivity scores and P300 amplitude remained after taking into account the number of childhood conduct disorder symptoms. This study supports the hypothesis that the basic neurophysiology responsible for the P300 amplitude in cocaine-dependent individuals is associated with impulsivity independent of a history of childhood conduct disorder symptoms.     

Interactive effects of hypertension and alcohol dependence on the P300 event-related potential in African-Americans.

Although hypertension and alcohol dependence have been linked by epidemiological surveys and clinical observations, their interactive effects on brain function have rarely been tested. The present study involved the recording of P300 event related potentials (ERP) from 106 middle-aged African-American adults assigned to one of four groups: normotensive/nondependent (n=56), hypertensive/nondependent (n=11), normotensive/dependent (n=27), and hypertensive/dependent (n=12). The numbers of Nicotine Dependence, Major Depressive Disorder, and Conduct Disorder symptoms were specified as covariates within a 2 by 2 factorial design. ERPs were recorded during separate visual and auditory oddball tasks. The major result was a synergistic effect of hypertension and alcohol dependence on auditory P300 latency: the combination of both factors was associated with greater slowing than the sum of their independent effects. Future studies should continue to examine the potential synergistic effects of alcohol dependence and hypertension with a view toward identifying and reducing neurophysiological decrements and stroke risk among middle-aged patients.     

Study of the P300 event-related potential through brain mapping in phonological dyslexics.

The auditory P300 was studied through brain mapping in 10 phonological dyslexics (7 M and 3 F), who were found to differ significantly from normals in presenting a longer P300 latency and smaller amplitude on the N2-P3 wave. Interesting too was the asymmetry of the P300 distribution between the two hemispheres, with less amplitude on the right. These findings confirm the hypothesis of reduced right hemisphere functioning during the process of information analysis in phonological dyslexics.     

血管源性痴呆的事件相关电位P300研究

目的 评价事件相关电位P300在血管源性痴呆（Vascular dementia,VD)认知功能障碍诊断中的价值。方法 对30例VD和30例正常人,利用磁共振成像（MRI）技术测定额叶,颞叶,顶叶,枕叶和海马结构的体积,采用简明精神状态量表（MMSE）,简易痴呆筛查量表（BSSD）和瑞文标准智力测验量表（RSPM）评定认知功能,记录分析听觉刺激诱发的事件相关电位P300。结果 （1）与正常对照比较,VD患者额叶和颞叶体积显著缩小,而顶叶,枕叶和海马结构的体积无显著差异。（2）VD患者MMSE,BSSD和RSPM3种量表的评分均显著低于正常对照。（3）VD患者MMSE、BSSD评分的降低与额叶,颞叶萎缩程度和局限病灶位于额叶,颞叶相关,（4）VD患者P300峰潜伏时（peak latency,PL)较正常对照明显延长,（5）VD患者P300PL的延长与额叶,颞叶的萎缩程度和局限病灶位于额叶,颞叶相关。（6）VD患者P300PL的延长与认知功能损害的严重程度相关,结论 （1）P300可以作为认知功能评价的额观指标。（2）VD患者额叶和颞叶的萎缩与其认知功能障碍有关。（3）P300PL的延长可反映VD患者脑局部病理改变。（4）P300PL的延长可客观反映VD患者认知功能损害的严重程度。（5）P300在临床上可以作为诊断VD的重要客观指标。     

The effect of the skull on event-related P300.

OBJECTIVES: Event-related potentials (EP) indicate neuronal processes with a high temporal resolution, while functional magnetic resonance imaging (fMRI) has a high spatial distribution. Information from both techniques may complement each other. However, this combination is fraught with difficulty because of a possible interference of the skull or the scalp with scalp-recorded EP. The aim of the present study was to investigate this influence of skull and scalp thicknesses on event-related P300 potentials. METHODS: Thirty healthy controls were examined using an auditory evoked P300 elicited by a standard oddball paradigm. Skull and scalp thicknesses were determined using coronal T2-weighted magnetic resonance imaging (MRI). RESULTS: P3b-amplitudes were significantly correlated with temporo-parietal skull thickness (r=-0.42; P=0.021; regression slope of -1.14 microV/mm skull thickness), whereas scalp had no influence on P300. The amplitude of the more frontal subcomponent P3a was not related to frontal skull thickness. CONCLUSIONS: Therefore, the utility of P300 as a research tool can be enhanced when adjustment for skull thickness is made.