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PubMed2004

Event-related potentials associated with sound discrimination versus novelty detection in children.

In children, deviant sounds in an oddball paradigm elicit a mismatch negativity (MMN) indexing discrimination of sound change and late difference negativity (LDN) with unknown functional significance. Salient sounds elicit an ERP index if orienting, P3a, and a late negative component, Nc. We compared children's responses elicited by moderate sound changes and novel sounds to examine the relationships between MMN and LDN, and LDN and Nc. Two components of the Nc, the Nc1 and Nc2, were identified. The scalp topography of LDN differed from those of the MMN and Nc1. Children's early P3a appeared mature but late P3a lacked frontal predominance. The findings suggested that LDN is not linked with either the sensory or attentional processing. It might reflect cognitive, albeit preattentive, processing of sound change. The Nc1 appears to reflect cognitive attentive processing of salient stimuli and the Nc2 might reflect reorienting after distraction.

Adolescent↗
PubMed2004

The application of jackknife-based onset detection of lateralized readiness potential in correlative approaches.

The onset of the lateralized readiness potential (LRP) represents an interesting parameter within mental chronometry. According to Miller, Patterson, and Ulrich (1998), reliability increases when LRP onsets are detected in jackknifed LRP waveforms. Until now, jackknifed LRP onsets could be analyzed in factorial designs only. The aim of the present study was to extend the application of jackknifing to correlative approaches (e.g., in personality research). Using different onset scoring techniques, in several simulations run on realistic LRP data jackknifing and single-subject procedures were compared regarding their estimates of a simulated true correlation. For all scoring techniques but regression, jackknifed coefficients were on average higher than the respective single-subject coefficients, and statistical power was higher. Overall, combining jackknifing with a 50%-relative onset criterion is recommended.

Algorithms↗
PubMed2004

Current-source density analysis of slow brain potentials during time estimation.

Two event-related potential studies were conducted to investigate differential brain correlates of temporal processing of intervals below and above 3-4 s. In the first experiment, 24 participants were presented with auditorily marked target durations of 2, 4, and 6 s that had to be reproduced. Timing accuracy was similar for all three target durations. As revealed by current-source density analysis, slow-wave components during both presentation and reproduction were independent of target duration. Experiment 2 examined potential modulating effects of type of interval (filled and empty) and presentation mode (randomized and blocked presentation of target durations). Behavioral and slow-wave findings were consistent with those of Experiment 1. Thus, the present findings support the notion of a general timing mechanism irrespective of interval duration as proposed by scalar timing theory and pacemaker-counter models of time estimation.

Acoustic Stimulation↗
PubMed2005

Age differences in attentional control: an event-related potential approach.

We examined age differences in event-related potentials (ERPs) associated with attentional control of task-set selection and response interference by means of a cue-based switching paradigm in which participants performed the color or word Stroop task. The results of ERPs in the cue interval indicated that P3 latencies were slowed for older adults, suggesting age-related slowing in updating currently relevant task sets. Older adults also showed a larger CNV under switching than nonswitching conditions, indicating age differences in maintaining task sets over longer periods of time. The results of target-locked ERPs revealed a negativity to incompatible Stroop trials (Ni) that was prolonged for older adults, suggesting age differences in early conflict processing. Response-locked ERPs showed a negative deflection to incompatible Stroop trials (CRN) only for younger adults, suggesting age differences also in response-related conflict processing.

Adult↗
PubMed2005

Are the anterior negativities to grammatical violations indexing working memory?

Anterior negativities obtained when a grammatical rule is violated may reflect highly automatic first-pass parsing processes, the detection of a morphosyntactic mismatch, and/or the inability to assign the incoming word to the current phrase structure. However, for some theorists these negativities rather reflect some aspect of working memory processes. Event-related brain potentials (ERPs) obtained for word category and morphosyntactic violations were directly compared with effects obtained when working memory is particularly demanded (embedding subject- or object-relative clauses), yielding a significant dissociation in terms of topography. Even though, the anterior negativities for grammatical violations vanished when relative clauses were embedded, suggesting that the processes reflected by anterior negativities related to grammatical violations and those related to working memory manipulations, even if different, are placing demands on a common pool of limited resources.

Adolescent↗
PubMed2005

The late Nd reflects a memory trace containing amodal spatial information.

The early Nd reflects the analysis of simple features of selectively attended auditory stimuli, but the precise nature of the more complex processing reflected by the late Nd is unclear. The late but not the early Nd is sensitive to interference from a concurrently presented visual spatial attention switching task. This experiment investigated whether the late Nd is also sensitive to deeper visual attention switching. Twenty-one subjects performed a dichotic listening task concurrently with either visual spatial or visual letter matching attention switching tasks. Late Nd amplitude was reduced by the spatial but not the letter matching task, indicating insensitivity to deeper attention switching. P300 amplitude was reduced by both tasks. Reductions in N100 and P200 were uncorrelated. We propose that, in part, the late Nd reflects an amodal memory trace containing spatial information, possibly involving a "where" rather than a "what" auditory pathway.

Adolescent↗
PubMed2005

Electrophysiological correlates of anticipatory task-switching processes.

Recent studies show a differential switch-related positivity emerging before a switch trial and reflecting anticipatory task-set reconfiguration processes. In this study, the switch-related positivity was examined in a cued task-switching paradigm. Cue-stimulus and response-stimulus intervals were independently manipulated to dissociate between the effects of anticipatory preparation and passive dissipation of task-set interference. Reaction time switch cost declined with increasing cue-stimulus and response-stimulus intervals, suggesting a contribution from both active preparation and passive interference processes. In cue-related difference waveforms, a switch positivity peaked around 350-400 ms and is interpreted as reflecting differential activation of task-set reconfiguration. In stimulus-related difference waveforms, a switch-related negativity is believed to indicate the role of S-R priming and response interference in task-switching.

Adolescent↗
PubMed1995

Low dose of ethanol suppresses mismatch negativity of auditory event-related potentials.

The acute effect of a low dose of ethanol (0.5 g/kg) on attention and auditory event-related potentials (ERPs) was investigated in 10 social drinkers using a single-blind, placebo-controlled cross-over design. A dichotic listening task, in which the subjects were instructed to attend selectively to stimuli to one ear while ignoring stimuli to the other, was used. The amplitudes of N1, P2, and the mismatch negativity (MMN) were significantly diminished by alcohol. The latencies of the MMN and N2b were also significantly increased after alcohol ingestion. The novel finding of the significant (> 60% reduction in amplitude) suppression of the MMN can be interpreted as indicating disturbed preconscious detection of acoustic changes outside the scope of attention. Because this is a prerequisite to an attentional shift, the MMN suppression may be related to increased risk for accidents after alcohol ingestion. The same dose of alcohol that suppressed the MMN left intact selective attention and conscious "target" detection, as reflected by the processing negativity and P3 deflections, thus suggesting that the automatic functions of human information processing are more sensitive to alcohol than the controlled, attentional functions.

Adult↗
PubMed1998

Mismatch negativity in young children of alcoholics from high-density families.

The mismatch negativity (MMN) component of event-related potentials was recorded from a group of young children of alcoholics (n = 19, 8 females) with a high-density family history of alcoholism and from a control group (n = 23, 12 females), between 8 and 15 years of age. A dichotic listening task was used, and subjects had to pay attention to an oddball paradigm in one ear and ignore the stimuli in the other ear. The event-related potentials elicited by the standard unattended tones were subtracted from those elicited by the infrequent deviant unattended tones, and the MMN was measured at 10 frontal and central electrodes. No group differences were observed in peak latency, peak amplitude, and mean amplitude of the MMN. These results indicated that preattentive mechanisms of mismatch detection were not impaired in young subjects at high risk for alcoholism. Results are discussed in relation to differences in electrophysiological indexes of automatic versus controlled information processing and in relation to the characteristics of the sample.

Adolescent↗
PubMed1995

Auditory event-related magnetic fields in a tone-duration discrimination task. Source localization for the mismatch field and for a new component M2".

Auditory event related magnetic fields were measured using an odd-ball paradigm in which the rare event was a tone of short duration, D2, and the frequent one a tone of longer duration, D1. The subjects were required to attend to and count the number of rare stimuli. In the average across target stimuli a mismatch field (MMF) occurs and the dependence of the MMF, especially its latency, on the tone duration D2 is examined in detail. The location of an equivalent current dipole for the MMF-source is found and turns out to be at variance with earlier results. In addition to the MMF we propose a new component, here called M2", which in time overlaps the magnetic equivalent of the P200 signal and which has a source location (equivalent current dipole) lying rather close to the MMF-source. The two sources are, however, active at latencies differing by a time equal to D2. We speculate that M2" indicates the onset of the process: "evaluation of tone-duration" while the MMF indicates the end of this process.

Acoustic Stimulation↗
PubMed1998

Bereitschaftspotential in amyotrophic lateral sclerosis (ALS): lower amplitudes in patients with hyperreflexia (spasticity).

In a pilot study the Bereitschaftspotential (BP) was investigated in 16 patients suffering from amyotrophic lateral sclerosis (mean age 58.6, mean severity of the illness according to Norris ALS score 76.4 points). Comparing the total ALS group (n=16) with matched controls no significant differences in the BP amplitude parameters were found. However, a subgroup of 7 ALS patients with signs of pronounced spasticity (hyperreflexia) differed significantly at the central midline from matched controls and significantly in addition from patients with a lower degree of spasticity. Controls as well as patients with a lower degree of spasticity had significantly higher BP amplitudes at the midline (electrode positions Cz and Pz, P<0.05, H-test). The correlation coefficient between the hyperreflexia Norris score and the various BP parameters for the total ALS sample (n=16) revealed a significant correlation especially over the midline. Stronger signs of spasticity (hyperreflexia) are associated with lower amplitudes of the BP.

Adolescent↗