P300 Latency Correlates with Digit Span

P300 latency from a simple auditory discrimination counting task was obtained along with a digit span memory task for a large group of neurologically normal subjects. Moderate significant negative correlations between the peak latency of the P3a and P3b subcomponents and total memory score were found, although no relationship was observed for other waveform component latencies and memory score. The data suggest that the P300 component of the event-related brain potential may index individual variations in memory ability.     

Event-Related Potentials and Recognition Memory For Pictures and Words: The Effects of Intentional and Incidental Learning

Event-related potentials were recorded under conditions of intentional or incidental learning of pictures and words, and during the subsequent recognition memory test for these stimuli. Intentionally learned pictures were remembered better than incidentally learned pictures and intentionally learned words, which, in turn, were remembered better than incidentally learned words. In comparison to pictures that were ignored, the pictures that were attended were characterized by greater positive amplitude frontally at 250 ms and centro-parietally at 350 ms and by greater negativity at 450 ms at parietal and occipital sites. There were no effects of attention on the waveforms elicited by words. These results support the view that processing becomes automatic for words, whereas the processing of pictures involves additional effort or allocation of attentional resources. The N450 amplitude was greater for words than for pictures during both acquisition (intentional items) and recognition phases (hit and correct rejection categories for intentional items, hit category for incidental items). Because pictures are better remembered than words, the greater late positive wave (600 ms) elicited by the pictures than the words during the acquisition phase is also consistent with the association between P300 and better memory that has been reported.     

On the Dependence of P300 Latency on Stimulus Evaluation Processes

McCarthy and Donchin (1981) found that the latency of a late positive component of the event-related potential (ERP) was influenced by the presence of noise in a stimulus matrix but not by the compatibility between the stimulus presented and the response required. They concluded that this component is a P300 and that its latency was influenced by stimulus evaluation but not by response selection processes. The present experiments were designed to confirm that the component identified by McCarthy and Donchin was indeed a P300 and to determine if its latency varies systematically with increases in stimulus evaluation time produced by graded changes in noise level. In Experiment 1, subjects performed a standard oddball task in which they were required to count the rarer of two stimuli (the words RIGHT or LEFT) which were, or were not, embedded in a noise matrix (characters from the alphabet). The positive component of the ERP, whose amplitude was larger for rare target stimuli, was labeled a P300, and the latency of this component was longer when the stimuli were embedded in noise. In Experiment 2, subjects performed a choice reaction time task. Following the procedures used by McCarthy and Donchin, stimulus words RIGHT and LEFT required right or left hand responses depending on the presence of a cue word SAME or OPPOSITE which preceded the stimulus. Stimulus words were presented in four different degrees of noise, the levels of which were manipulated by varying the set size of the alphabetic characters which could surround the stimulus words. Reaction time increased both with noise (by 325 ms) and as a function of stimulus-response incompatibility (by 127 ms). In contrast, P300 latency increased substantially with noise (by 200 ms) but, to a much lesser extent (by 14 ms), with response incompatibility. These results indicate that the P300 is sensitive to the ease with which a target stimulus can be discriminated from noise. They confirm that P300 latency can be used as a measure of the timing of stimulus evaluation processes that is relatively independent of response selection and execution.     

认知事件相关诱发电位P300的研究进展

目的 探讨认知事件相关诱发电位（ERP）P300的研究进展。方法 在万方数据、Pubmed等数据库查阅与认知ERP P300研究相关的文献,进行汇总分析。结果 ERP P300反映了大脑认知的加工过程,可对痴呆、脑血管疾病、脑外伤、癫痫、精神疾病等多种疾病进行早期认知减退的检测、认知功能和损害程度的评估以及认知功能的定量分析,具有较广泛的临床应用价值。但P300的临床应用存在没有业内公认的评定标准值、实际检测中影响因素较多等问题,其具体机制及相关问题的解决还有待于进一步更深入地探讨。结论 P300可以检测大脑神经细胞的动态认知过程,具有可靠、有效、客观、无创伤等特点,是其他脑影像技术所不能取代的一种检测方法。未来还需在P300及其亚波的产生定位及临床诊断的统一化标准化等方面做进一步的深入探索和研究。     

P300 Latency and Digit Span

The relationship betweeen P300 latency and digit span reported by Polich, Howard, and Starr (1983) is re-examined. Evidence is presented which shows that these authors' use of partial correlation to correct for age differences in their sample of subjects is erroneous because the assumption of linear regression is clearly not satisfied. This finding seriously questions Polich et al.'s conclusion that P300 latency and digit span covary irrespective of any relationship of the variables to age.     

The n-back as a dual-task: P300 morphology under divided attention

The n-back task was hypothesized to be a dual task, permitting the imposition of parametrically increasing attentional and working memory demands, while keeping constant the demands of an embedded matching subtask. Visual targets were presented for 200 ms every 2.2 s at pseudorandomly varying positions on a computer screen. Participants were required to remember the most recent 0, 1, 2, or 3 positions and responded with a choice button push to whether the current target position matched the position presented n items previously. P300 peak latency was constant across n-back tasks, reflecting constant perceptual and cognitive demands of the matching subtask. P300 peak amplitude decreased with increasing memory load, reflecting reallocation of attention and processing capacity away from the matching subtask to working memory activity. These data support a dual-task nature of the n-back, which should be considered when employing this paradigm.     

Taking Attention to Task: P300, Task Response Probability, and Within-Category Deviation Detection

Previously, we reported enhanced P3 amplitudes to between-category deviations among high and low probability events. Here, we tested the effects of a within-category difference. Subjects performed a go/no-go button press task as they viewed repeated, randomly-ordered presentations of nine double-digit numbers. Eight numbers fell within a prescribed range (42-49, standards); prior to testing, subjects selected one standard number for later recall. A ninth, out-of-range (91, deviant) number was also included. Subjects were tested under two conditions, in which they responded either to one (low response probability) or to seven (high response probability) standard nonselected numbers, designated as targets. Relatively larger P3s were consistently apparent only when the deviant nontarget was associated with a low probability response to a nontarget. There was a selective effect of nontarget response probability on P3 amplitude to the deviant nontarget. Our results indicate that within-category deviation detection is facilitated by "controlled" attention to the structure of the stimulus field.     

Functional Differences Between Members of the P300 Complex: P3e and P3b

The main findings of this study bear upon differences in the functional roles of P3b and a shorter latency, more centrally distributed endogenous positive component denoted as P3e. At the present writing, we have observed P3e only in conjunction with P3b. As in the case of P3b, P3e is fully endogenous in that it can be- elicited by omission of a stimulus if stimulus omission conveys relevant information to the subject. It was found that P3e and P3b relate differently to information delivery. Information delivery was manipulated by varying event probabilities and the discriminability of the events. The well known properties of P3b, namely that its amplitude is large when elicited by low probability (high information content) events and is reduced by perceptual difficulty (information loss-equivocation), were replicated in the current study. In contrast to P3b, variation of event probability had no effect upon P3e amplitude, but increased perceptual difficulty markedly reduced P3e amplitude. In addition, two CNV-type negativities were observed in the epochs prior to presentation of the informative signal event: 1) A negativity that was maximal over central scalp related to the subject's prediction that a rare or frequent event would be presented; 2) A negativity that was maximal over occipital scalp related to a stimulus that informed the subject whether the subsequent discrimination of the signal would be easy or difficult. Finally, there was a serendipitous Hading of an apparently new short duration component, tentatively labeled Px, which is elicited by presentation of the signal that informs the subject whether the subsequent discrimination will be easy or difficult.     

Second Thoughts: Multiple P300s Elicited by a Single Stimulus

In a previous report (Johnson & Donchin, 1978), we manipulated the discriminability of tone pairs that delivered feedback information in a time-estimation paradigm. As in other experiments using feedback stimuli, the event-related potentials elicited by these stimuli did not return to baseline in the 800-ms poststimulus interval. Since we were interested in this “Slow Wave'’activity, the poststimulus interval was lengthened to 1500 ms. Averages revealed that a second positive peak was present for some of the individual subjects. To investigate this activity further, the filtered singletrial waveforms were inspected visually. These data were characterized by the presence of one, and occasionally two, positive peaks, with highly variable latencies, following the P300. These peaks were indistinguishable in frequency and general appearance from the P300s elicited by the feedback stimuli. After latency adjusting the waveforms on the peak of the second positive wave, amplitude and latency were quantified. Whereas P300 amplitude was directly related to stimulus discriminability and positive feedback elicited larger P300s than negative feedback, the amplitude of the second positive wave was constant across levels of discriminability and the same for both types of feedback. In contrast, the latencies of both waves were inversely related to stimulus discriminability and shorter following positive feedback than negative feedback. Evidence is presented to support our contention that these additional positive peaks represent P300 activity. The data are discussed in terms of what these multiple P300s reveal about human information processing.     

Schizophrenia: the broken P300 and beyond.

Many of the social, economic, and political problems facing people with schizophrenia are due to a misconception in the community that schizophrenia is not a biologically based disease but a myth. Because the diagnosis is based on self-reported symptoms, it is difficult for many people to acknowledge that schizophrenia is real. One goal of psychophysiological research has been to anchor both diagnosis and symptoms in biological reality. Reduction of the amplitude of the P300 component of the event-related potential (ERP) is the most replicable biological marker of the disease. Data are presented suggesting that P300 is both a state and a trait marker of the disease and may be sensitive to the progressive/degenerative course of the disease. Although the P300 tracks changes in clinical symptoms, it remains reduced even in patients in relative remission. P300 amplitude reduction is related to enduring negative symptoms, waning of attention, and gray matter volume deficits. ERP components other than P300 can also manifest the biological reality of various symptoms of the disease.     

P300, Probability, and Interstimulus Interval

The relationship between target stimulus probability and interstimulus interval on the P300 (P3) component of the event-related potential was assessed in three experiments. In each study an auditory discrimination paradigm was employed wherein subjects indicated with a finger tap response the occurrence of a randomly presented 2000 Hz target tone embedded in a series of 1,000 Hz tones. Target stimuli were presented with a probability of either .20 or .80 in different conditions which were combined factorially with different interstimulus intervals. Experiment 1 presented stimuli at 2.0, 2.5, or 3.0 second intervals; Experiment 2 presented stimuli at 2.0, 3.0, or 4.0 second intervals; Experiment 3 presented stimuli at 4.0, 6.0, or 10.0 second intervals. P3 amplitude was larger for the .20 relative to the .80 target probability conditions for the shorter interstimulus intervals but not for the longer intervals. P3 latency was consistently longer for the .20 relative to the .80 target probability conditions, with generally little effect observed for interstimulus interval changes. The results suggest that interstimulus interval affects component amplitude by determining the amount of processing resources available when the P3 is produced.     

P300 and Recall in an Incidental Memory Paradigm

In previous research Karis, Fabiani, and Donchin (1984) found a relationship between the amplitude of the P300s elicited by words and subsequent recall performance. Words later recalled elicited larger P300s than words later not recalled. However, this relationship was dependent on the mnemonic strategies used by the subjects. There was a strong relationship between P300 amplitude and recall when rote rehearsal strategies were used, but when subjects used elaborative strategies the relationship between P300 amplitude and recall was not evident. In the present experiment we employed an incidental memory paradigm to reduce the use of rehearsal strategies. An “oddball’ task consisting of a series of names was presented, and subjects were required to count either the male or the female names. Event-related brain potentials were recorded to the presentation of each name. Following the oddball task, subjects were asked, unexpectedly, to recall as many names as possible. The names that were recalled had elicited, on their initial presentation, larger P300s than names not recalled. Thus, these results confirm our hypothesis: when elaborative rehearsal strategies are not used, the relationship between P300 and memory emerges more consistently. Our data provide support for a “context updating’ hypothesis of the functional significance of the P300.     

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.     

P300 and S-R Compatibility: A Reply to Magliero et al.

Some recent papers have been devoted to simultaneous analysis of RT and P300 latency effects with S-R compatibility. This, indeed, can be particularly fruitful since it may provide some insight into response choice, a crucial stage of information processing taking place between stimulus analysis and response production. Apparent contradictions have arisen between these studies because of the different kinds of S-R compatibilities involved. The aim of this reply is to emphasize the discrepancies between experimental designs that use semantic versus spatial compatibilities.     

"...'Twas ten to one; and yet we ventured...": P300 and decision making

In some situations subjects' predictions of future events do not accurately reflect the subjective probability associated with these events. We set up such a situation by manipulating the payoff structure in a prediction paradigm, and found that P300 provides an index of the processes responsible for subjective probability, or expectancy, not obtainable from overt predictions. Sixteen subjects were required to predict, on each trial, whether a 1, 2, or 3 would appear on a display. The numbers appeared randomly with probabilities .45, .10, and .45, respectively. In one condition subjects were given bonuses according to an all-or-none payoff function in which they received one cent if they predicted correctly, and nothing if they were incorrect. In a second condition bonuses were determined by a linear payoff function in which subjects were paid one cent if they predicted correctly, and one-half cent if they were off by one (e.g., predict 1 and 2 appears). After each condition subjects estimated the actual number of stimuli presented. These estimates were the same for both conditions, although predictions differed radically, with 2 predicted much more frequently in the linear condition. P300 area was largest for the rare event (2), and the relationship between P300 and probability was unaffected by payoffs. Our design did introduce differences between conditions in the overall “riskiness’ of predictions, and the strategies adopted by most subjects also resulted in differences in the salience, or task relevance, of the feedback stimuli. These differences resulted in an overall increase in P300 in the all-or-none condition. A relationship also emerged between the subjects' strategies and their ERPs. Subjects who adopted more effective strategies responded differentially to feedback from high and low risk predictions, whereas the others did not.     

Impulsivity, intelligence and P300 wave: An empirical study

The aim of this study was to analyze the relationships among impulsivity, intelligence and P300, a well-known component of the event-related potential widely studied in personality and intelligence research. Eighty-two males completed the Barratt Impulsiveness Scale and the two-subtest form of the Wechsler Abbreviated Scale of Intelligence. A subsample of 45 participants (mean age=24.4, SD=4.6) performed a visual oddball task, consisting of a two-letter recognition task, during which psychophysiological data were recorded. Although no significant relationships emerged for P300 latency, overall results suggest that the P300 amplitude was positively related to IQ and negatively related to impulsivity. Those who scored high on impulsivity (high impulsives) had lower P300 amplitudes than low impulsives, but this relationship was not significant when controlling for individual differences in mental ability. The results also showed an inverse relationship between mental ability and impulsivity. That is, high impulsives demonstrated reduced cognitive performance on intelligence testing and it is reflected in their reduced P300 amplitude. These findings are likely due to high impulsives' less efficient ability to inhibit task-irrelevant information or to ignore additional information intake. It was suggested that impulsivity exerts a disadvantageous influence on the performance of tasks (such as those used on intelligence tests) in which exclusive concentration and sustained attention are necessary.     

Seasonal photoperiod,gender, and P300

The photoperiod model of seasonal affective disorder (SAD) suggests that SAD is caused by abnormal responses to seasonal changes in day length. Clarifying the utility of event-related brain potentials (ERPs) as diagnostic aids or measures of therapeutic efficacy in SAD requires understanding the range of naturally occurring seasonal patterns of variation in human responses. This investigation studied ERPs from non-patients (402 from men, 415 from women) during the pronounced photoperiod variation of the Alaskan subarctic where light availability ranges from 3.20 h in winter to 21.98 h in summer. ANOVA showed significant (P=0.03) main effect of photoperiod in the amplitude and latency of P300 responses, as well as a main effect of sensory modality (P=0.002). There was neither a main effect of gender, nor any significant gender-interactive effect in ERP responses. In clients with SAD, the ERP variability attributed to seasonal photoperiod remains to be clarified.     

Identification of neural circuits underlying P300 abnormalities in schizophrenia.

Event-related potentials (ERPs) provide a noninvasive method to evaluate neural activation and cognitive processes in schizophrenia. The pathophysiological significance of these findings would be greatly enhanced if scalp-recorded ERP abnormalities could be related to specific neural circuits and/or regions of the brain. Using quantitative approaches in which scalp-recorded ERP components are correlated with underlying neuroanatomy in schizophrenia, we focused on biophysical and statistical procedures (partial least squares) to relate the auditory P300 component to anatomic measures obtained from quantitative magnetic resonance imaging. These findings are consistent with other evidence that temporal lobe structures contribute to the generation of the scalp-recorded P300 component and that P300 amplitude asymmetry over temporal recording sites on the scalp may reflect anatomic asymmetries in the volume of the superior temporal gyrus in schizophrenia.     

On P300 Latency and Correlational Inference

The use of statistical correlations to determine the underlying relationships between P300 latency, memory function, and aging is discussed. Similar correlational patterns obtained over a variety of subject populations can strengthen inferences about the specific associations among these variables. Partial correlation techniques can facilitate such inferences only when all factors are linearly related.     

P300 wave elicited by a stimulus-change paradigm in acutely prepared rats

Presentation of a long sequence of stimuli in one modality followed by infrequent substitution of stimuli in a different modality produced a very large P300 wave in the evoked potential to the infrequent stimulus. The P300 wave was never observed in a repetitive train of stimuli in one modality or to the background stimuli during the stimulus-change procedure. This phenomenon was observed in cortical recordings from anesthetized rats. This P300 wave corresponds in latency to that observed in human cognitive studies, and the use of this paradigm in animal studies could greatly facilitate work to determine the neural basis of the P300 wave.