Stimulus presentation rate dissociates sequential effects in event‐related potentials and reaction times

This study investigated the effect of variable interstimulus intervals (ISIs) on behavioral reaction time (RT) and on the latency and amplitude of the auditory P300 using an auditory continuous performance task (ACPT) paradigm. Twenty subjects were instructed to respond to common stimuli and ignore a rare stimulus. Common stimuli were 1000-, 1500-, and 2000-Hz pure tones. The rare stimulus was a 250-Hz pure tone. ISIs of 1, 2, and 4 seconds were used for this investigation. A significant correlation between ISI, reaction time, P300 latency, correct rejections, and false alarm rates was found. A significant correlation between P300 latency, P300 amplitude, correct rejections, and false alarm rates was also observed. Likewise, a statistically significant increase in reaction time (RT) was observed as ISI increased. The ACPT paradigm in conjunction with the auditory P300 response can measure both behavioral and electrophysiologic changes that occur during active auditory attention and auditory cognitive processing tasks.

The temporal selectivity of additive factor effects on the reaction process revealed in ERP component latencies

SummaryThe neural responses that distinguish novel from familiar items in recognition memory tasks are remarkably fast in both humans and nonhuman primates. In humans, the earliest onsets of neural novelty effects emerge at about ∼150–200 ms after stimulus onset [1–5]. However, in recognition memory studies with nonhuman primates, novelty effects can arise at as early as 70–80 ms [6, 7]. Here, we address the possibility that this large species difference in onset latencies is caused experimentally by the necessity of using reward reinforcement to motivate the detection of novel or familiar items in nonhuman primates but not in humans. Via magnetoencephalography in humans, we show in two experiments that the onset of neural novelty signals is accelerated from ∼200 ms to ∼85 ms if correct recognition memory for either novel or familiar items is rewarded. Importantly, this acceleration is independent of whether the detection of the novel or the familiar scenes is rewarded. Furthermore, this early novelty effect contributed to memory retrieval because neural reward responses, which were contingent upon novelty detection, followed ∼100 ms later. Thus, under the contextual influence of reward motivation, behaviorally relevant novelty signals emerge much faster than previously held possible in humans.

Auditory P300 event related potentials and serotonin reuptake inhibitor treatment in patients with fibromyalgia

Age differences in P3-reaction time associations

Objective: The aim of this study was to investigate changes in P3 amplitude and latency to emotional stimuli with different arousal and valence levels after a mindfulness-based intervention in oncological patients. Methods: P3 amplitude and latency at Fz, Cz, and Pz to emotional salient stimuli differing in valence (positive vs. negative) and arousal (low vs. high) levels were measured in 17 oncological patients (Mage = 51 years, SD = 9.17, females = 11) before and after a mindfulness-based intervention in a waitlist-controlled clinical trial. Group sessions were held 2x/week over a period of 5 weeks. Results: Arousal and valence levels of emotional salient stimuli were significant modulators of P3 amplitudes (P = .050; P = .006, respectively). P3 amplitudes at Fz decreased significantly from pre-waitlist to post-intervention (P = .002). P3 latency for negatively valenced stimuli decreased from pre- to post-intervention with trending significance (P = .080). P3 latency at Pz showed a trend of being shorter than P3 latency at Cz (P = .066). Depressive symptoms showed a decreasing trend from pre- to post-treatment (P = .075). Conclusions: We could show that arousal and valence levels of emotional salient stimuli are important modulators of P3 amplitudes and latencies in oncological patients. P3 amplitudes at Fz decreased significantly from pre-waitlist until after mindfulness-based intervention, decreases from pre-to post-intervention were linear, but not significant. In oncological patients the mindfulness-based intervention seems to have its strongest effect on the frontal electrode Fz, not the electrode Pz where its amplitude was largest. Depressive symptoms could be reduced.

: The current study evaluated the relationship between reaction time performance and the visual target-evoked P3 event-related potential (ERP) using a dynamic rapid serial visual presentation (RSVP) task. Electroencephalography (EEG) and reaction time measures were obtained while observers monitored an RSVP stream of short videos for infrequent targets presented among frequent nontarget distractors. Observers reaction time quartiles were used as ERP binning parameters for target- and response-locked EEG epochs. This procedure allowed us to assess neural activity related to perceptual and response processing across different levels of overt performance. P3 amplitude and latency were evaluated for both stimulus and response-locked averages. The results showed that the peak latency of the stimulus-locked P3 was maximal over central parietal electrode Pz and was significantly different between each quartile; however, these latency differences were absent when P3 latency was measured in the response-locked data. The P3 amplitude analysis revealed no significant differences between stimulus and response-locked averages within each quartile. Overall, the results suggest the peak latency of the P3 obtained in the current study reflects processes more associated with motor planning and response execution.

The P3 amplitude is augmented by decrements in target-probability, increments in the number of nontargets preceding the target, and extensions of the interstimulus interval (ISI). Each of these changes prolongs the target-to-target interval (TTI) and, consequently, results attributed to these factors might, at least partially, be accounted for by the TTI. Recent research also indicates that the P3s elicited by targets in one-, two-, and three-stimuli tasks (in which the TTI remains invariant) are similar. However, the TTI has not been examined systematically in previous research. The present study had subjects listen to a randomized ISI (0.5, 1, 2, or 4 s) version of the auditory oddball task in which targets occurred after one, two, three, four, or five nontargets. Event-related potentials were analyzed based on ISI, sequential structure, and TTI. The study examined sequence and ISI effects independent of TTI effects and demonstrated that extensions of ISI affected N1 but not P3 amplitude, extensions of TTI enhanced P3 amplitude independent of sequential structure, and sequential structure failed to influence P3 amplitude when TTI was controlled.

Visual event-related potentials (ERPs) were examined in 16 children (aged 5-14 y) with phenylketonuria (PKU) and 16 age- and sex-matched controls. Lifetime median measures of phenylalanine (Phe) were 230-460 micromol/l. The most recent Phe levels were 56-624 micromol/l. ERPs were recorded whilst the children performed a discrimination task. All stimuli were square wave gratings degree, which appeared for 33 ms. A response to an infrequent grating that differed in orientation or spatial frequency was required. The older children with PKU had a delay in the first peak (P1) of the ERP, and age-related changes in the amplitude of P1. There was attenuation of the second peak across age groups in PKU. There was no evidence of reduced response accuracy or longer reaction times in children with PKU. Latencies of the cognitive P3 were not delayed in PKU. The delayed early peaks are consistent with previous studies that have shown delayed visual evoked potentials in PKU. The lack of differences in reaction time and P3 may be due to relatively good Phe control in children with PKU, or to the simplicity of the task. Suggestions are made for future ERP studies of PKU.

Second language (L2) learners experience challenges when word meanings differ across L1 and L2, and often display crosslinguistic influence (CLI) in speech production. In contrast, studies of online comprehension show more mixed results. Therefore, this study explored how L2 learners process fine-grained L2 verb semantics in the domain of caused motion (placement) and specifically the impact of having similar vs. non-similar semantics in the L1 and L2. Specifically, we examined English (20) and German (21) L2 learners of Swedish and native Swedish speakers (16) and their online neurophysiological processing and offline appropriateness ratings of three Swedish placement verbs obligatory for placement supported from below: sätta “set,” ställa “stand,” and lägga “lay.” The learners’ L1s differed from Swedish in that their placement verbs either shared or did not share semantic characteristics with the target language. English has a general placement verb put, whereas German has specific verbs similar but not identical to Swedish, stellen “set/stand” and legen “lay.” Event-related potentials (ERPs) were recorded while participants watched still frames (images) of objects being placed on a table and listened to sentences describing the event with verbs that either matched the image or not. Participants also performed an offline appropriateness rating task. Both tasks suggested CLI. English learners’ appropriateness ratings of atypical verb use differed from those of both native Swedish speakers’ and German learners, with no difference in the latter pair. Similarly, German learners’ ERP effects were more similar to those of the native Swedish speakers (increased lateral negativity to atypical verb use) than to those of the English learners (increased positivity to atypical verb use). The results of this explorative study thus suggest CLI both offline and online with similarity between L1 and L2 indicating more similar processing and judgments, in line with previous production findings, but in contrast to previous ERP work on semantic L2 processing.

In this experiment, which was concerned with reaction times to regularly recurring visual stimuli, four experienced Ss made 21 serial responses at eight interstimulus intervals with eight replications each. The experiment was designed to provide answers to the following questions. With regularly recurring visual stimuli, (a) what is the relationship between foreperiod length and mean reaction time to light at the asymptote of the reaction time practice curve, and (b) what are the differences, for various foreperiod lengths, in the effects of practice on mean reaction time to light? The predicted answers to both questions (a) and (b) were confirmed. First, the relationship between interstimulus time interval and reaction time to regularly recurring visual stimuli is best depicted as an increasing function which reaches an asymptote at a different time interval for each S. In addition, practice results in a greater decrease in reaction time for the 1- and 2-sec. interstimulus intervals, and especially for the former, than for longer intervals; this effect is most pronounced after one experience with the given interstimulus interval.

In synaesthetes, stimulation of one sensory pathway provokes a sensory experience (e.g. a colour concurrent) in a different sensory modality or sub-modality. Results of synaesthetic Stroop and priming tests indicate that the perception of a colour concurrent interferes with the processing of a veridical colour in synaesthetes. We here examined the congruency between a stimulus' colour and the colour concurrent both in grapheme-colour synaesthetes and in non-synaesthetes trained on grapheme-colour associations. Electrophysiological (electroencephalogram) and behavioural measurements were collected during a priming task that included grapheme-grapheme and grapheme-colour patch pairs. To investigate covert bidirectional synaesthesia, an additional inverted colour patch-grapheme condition was included. Both groups of participants showed longer reaction time and more negative-going N300 and N400 event-related potential (ERP) components on incongruent trials. Whereas ERP effects in the non-synaesthetes were largely confined to the late cognitive components N300, P300 and N400, the synaesthetes also showed congruency-dependent modulation of the early sensory component N170. Our results suggest that early cognitive processes distinguish cross-modal synaesthetic perceptions from acquired associations. The involvement of both early- and late-stage cognitive components in bidirectional synaesthesia possibly indicates similar feature-binding mechanisms during processing of opposite flow directions of information, namely grapheme-colour and colour-grapheme.

The cognitive mechanisms underlying deception: An event-related potential study

The present study evaluated the use of slow rates of stimulus presentation on the accuracy of the N1-P2 cortical response in estimating hearing threshold. Long interstimulus intervals (ISI) allow the non-specific component of the N1 response to emerge, believed to reflect widespread cortical arousal that facilitates sensory and motor responses. We examined whether the non-specific N1 would be elicited at intensity levels near threshold. Event-related potentials were recorded to 0.5-, 1.0, and 4.0-kHz tone bursts with a long ISI (8–12 s) while the eleven subjects read a book. The stimulus level varied from -5 to 45 dB nHL. The 1.0-kHz tone burst was also presented with a shorter ISI (1.5–2.5 s), akin to that typically used in the audiological setting. The amplitude of N1-P2 was significantly enhanced in the long compared to short ISI condition, but, importantly, only for the stimuli with a level ≥25 dB nHL. Therefore, the N1-P2 recorded with long ISIs was not more precise in estimating threshold than that recorded with short ISIs, remaining visible to within 10 dB of behavioural threshold.

Slow potential changes and choice reaction time as a function of interstimulus interval