Joachim Hohnsbein

ERP components on reaction errors and their functional significance: a tutorial.

Some years ago we described a negative (Ne) and a later positive (Pe) deflection in the event-related brain potentials (ERPs) of incorrect choice reactions [Falkenstein, M., Hohnsbein, J., Hoormann, J., Blanke, L., 1990. In: Brunia, C.H.M., Gaillard, A.W.K., Kok, A. (Eds.), Psychophysiological Brain Research. Tilburg Univesity Press, Tilburg, pp. 192-195. Falkenstein, M., Hohnsbein, J., Hoormann, J., 1991. Electroencephalography and Clinical Neurophysiology, 78, 447-455]. Originally we assumed the Ne to represent a correlate of error detection in the sense of a mismatch signal when representations of the actual response and the required response are compared. This hypothesis was supported by the results of a variety of experiments from our own laboratory and that of Coles [Gehring, W. J., Goss, B., Coles, M.G.H., Meyer, D.E., Donchin, E., 1993. Psychological Science 4, 385-390. Bernstein, P.S., Scheffers, M.K., Coles, M.G.H., 1995. Journal of Experimental Psychology: Human Perception and Performance 21, 1312-1322. Scheffers, M.K., Coles, M. G.H., Bernstein, P., Gehring, W.J., Donchin, E., 1996. Psychophysiology 33, 42-54]. However, new data from our laboratory and that of Vidal et al. [Vidal, F., Hasbroucq, T., Bonnet, M., 1999. Biological Psychology, 2000] revealed a small negativity similar to the Ne also after correct responses. Since the above mentioned comparison process is also required after correct responses it is conceivable that the Ne reflects this comparison process itself rather than its outcome. As to the Pe, our results suggest that this is a further error-specific component, which is independent of the Ne, and hence associated with a later aspect of error processing or post-error processing. Our new results with different age groups argue against the hypotheses that the Pe reflects conscious error processing or the post-error adjustment of response strategies. Further research is necessary to specify the functional significance of the Pe.

Action monitoring, error detection, and the basal ganglia : an ERP study

The error negativity (Ne or ERN) is an event-related brain potential component, which is assumed to reflect error detection. Recently it has been hypothesized that the basal ganglia are assumed to play a crucial role in error detection. In the present study we ask whether the Ne is altered in patients with Parkinsons disease (PD), who have an impaired function of the basal ganglia. We recorded the Ne in patients and in matched controls, while they performed different tasks that require a relatively high cognitive control, which is supposed to pose particular problems on PD. The Ne was in fact smaller in the patients than in the controls in all tasks. Our results suggest an impairment of error detection in PD for different types of demanding tasks. This supports the hypothesis that the basal ganglia do play an important role for error detection in action monitoring.

Late ERP components in visual and auditory Go/Nogo tasks

In an audio-visual Go/Nogo paradigm we studied whether the Go/Nogo difference, usually found in the time range of the visual N2, is also present after auditory stimuli, which bears on the common response inhibition hypothesis of this N2 effect. Moreover the possible presence and variation of P300 subcomponents were studied with the goal of clarifying the reasons for the commonly observed P300 topography changes between Go and Nogo trials. To disentangle possible P300 subcomponents we applied a crossmodal divided attention (DA) condition, in which the subcomponents are known to be separated after auditory stimuli in choice tasks. An N2 effect was found after visual but not after auditory stimuli, which is evidence against the response-inhibition hypothesis. After visual stimuli a positive complex (P400) was seen, whereas after auditory stimuli two dissociated components (P400 and P507) were found instead. The P507 had a parietal maximum for both Go and Nogo trials. It was larger and it peaked later in Go than in Nogo trials. The P400 showed topographic differences between Go and Nogo trials, which could be explained by the overlap of the two subcomponents. We assume that (i) both subcomponents have a stable topography across response type, and (ii) the first subcomponent is invariant with response type, whereas the second (which overlaps the first one) is larger and peaks later on Go than on Nogo trials.

Inhibition-Related ERP Components: Variation with Modality, Age, and Time-on-Task

Abstract In Go/Nogo tasks, the ERP after Nogo stimuli generally reveals a negativity (Nogo-)N2 and a subsequent positivity (Nogo-)P3 over fronto-central scalp regions. These components are probably related to different subprocesses serving response inhibition, namely, modality-specific and general inhibition, respectively. In the present study we investigate whether aging or prolonged work (“time-on-task”) have an effect on N2 and P3. Twelve young and 12 elderly subjects performed simple Go/Nogo tasks to visual or auditory letter stimuli. Reaction times were longer after visual than after auditory stimuli, and longer in the elderly than in the young. The ERP results reveal a slight impairment of modality-specific inhibition (N2) in the elderly after visual, but not after auditory, stimuli. General inhibition (P3) was delayed in the elderly for both modalities, as was Go-P3 and RT. Hence, it appears that the response slowing of the elderly is the result of a slowing of the decision process whether to respo...

Parallel systems of error processing in the brain.

Major neurophysiological principles of performance monitoring are not precisely known. It is a current debate in cognitive neuroscience if an error-detection neural system is involved in behavioral control and adaptation. Such a system should generate error-specific signals, but their existence is questioned by observations that correct and incorrect reactions may elicit similar neuroelectric potentials. A new approach based on a time-frequency decomposition of event-related brain potentials was applied to extract covert sub-components from the classical error-related negativity (Ne) and correct-response-related negativity (Nc) in humans. A unique error-specific sub-component from the delta (1.5-3.5 Hz) frequency band was revealed only for Ne, which was associated with error detection at the level of overall performance monitoring. A sub-component from the theta frequency band (4-8 Hz) was associated with motor response execution, but this sub-component also differentiated error from correct reactions indicating error detection at the level of movement monitoring. It is demonstrated that error-specific signals do exist in the brain. More importantly, error detection may occur in multiple functional systems operating in parallel at different levels of behavioral control.

Short-term mobilization of processing resources is revealed in the event-related potential

This study investigates whether an occasional effortful improvement of performance, as asked for by a precue, is reflected in event-related potential (ERP) changes. To estimate the limits of possible effort-induced behavioral and ERP changes, we manipulated the time between precue and imperative stimulus (IS; precue interval, PCI). The subjects could, in fact, improve their performance in the effort trials, with all but the shortest PCI. The postcue ERP revealed a fronto-central contingent negative variation (CNV), which was preceded by a frontal positive/occipital negative wave (P2/N2). Both the P2/N2 and the CNV were larger for effort than for standard trials for all PCIs. For the shortest PCI (300 ms), the CNV increase was seen after the IS. The CNV increase for PCIs 600 and 300 began at about 400 ms postcue. The results suggest that effortful performance improvement is associated with prior increase of a frontocentral CNV and a preceding P2/N2. The CNV increase is thought to reflect the activity of a frontal executive process by which additional processing resources can be mobilized on a trial-to-trial basis within less than 500 ms.

Flanker interference in young and older participants as reflected in event-related potentials.

The present study investigates behavioural and event-related potential (ERP) differences between young and older participants in two variants of a flanker task. Flankers preceded the target by 100 ms (Experiment 1) or were presented simultaneously with the target (Experiment 2). In both experiments the response times showed an age-related slowing and a compatibility effect, which did not differ significantly across age. The older participants committed only half as many errors as the young ones. The visual ERPs revealed that the speed of visual perception was similar between groups. In addition the processing of the targets, but not of the flankers, appeared to be enhanced in the older participants. Moreover the lateralized readiness potential (LRP) started later and was larger for old vs. young participants, which was most pronounced for the incorrect LRP activation due to the flankers. The LRP amplitude effect is due to an enhanced activation over contralateral motor areas, which appears to be a general finding unrelated to the error rate. In summary, in the present study we could not find evidence for enhanced flanker interference in the performance of older compared to young participants. The reduced error rates for older participants are likely due to enhanced processing of the targets and delayed transmission of flanker information from visual to motor areas.

Dynamic Visual Capture: Apparent Auditory Motion Induced by a Moving Visual Target

Apparent motion of a sound source can be induced by a moving visual target. The direction of the perceived motion of the sound source is the same as that of the visual target, but the subjective velocity of the sound source is 25–50% of that of the visual target measured under the same conditions. Eye tracking of the light target tends to enhance the apparent motion of the sound, but is not a prerequisite for its occurrence. The findings are discussed in connection with the ‘visual capture’ or ‘ventriloquism’ effect.

A new method for the estimation of the onset of the lateralized readiness potential (LRP)

The aim of this work was to develop a new method for the estimation of the onset of the lateralized readiness potential (LRP). In contrast to the known methods that use only restricted data segments for estimation, the proposed segmented regression (SR) method employs the LRP trace from the stimulus onset to the LRP peak. Comparison of the SR with two other methods, done with both simulated and real data, shows that the SR method yields a relatively unbiased absolute onset time that is not affected by different LRP gradients before and after the onset. Moreover, the SR estimator proved to be quite sensitive to subtle onset differences across conditions.

The human frequency-following response (FFR): Normal variability and relation to the click-evoked brainstem response

The frequency-following response (FFR) was recorded from twenty human subjects (11 female and 9 male) over a frequency range of 128-832 Hz in order to study the normal variability of this evoked potential and its dependence on age and sex. Moreover the relation of the FFR to the click-evoked brain stem response (BER) was analyzed in order to contribute to the FFR source discussion. The FFR had a maximum amplitude of about 400 nV and a latency of about 6.4 ms for stimulus frequencies around 350 Hz; the inter-individual variance of the best frequency and of the shape of the frequency function was considerable. Large second harmonics were seen in the FFR to stimuli below about 200 Hz. The FFR amplitude tended to be larger in younger subjects, whereas no such effect was found for the BER. No significant sex effect was found for the FFR amplitude, whereas the BER waves IV and VI were larger for females than for males. There were no correlations between FFR and BER latencies. Significant correlations were found between the amplitudes of the FFR and BER components II, III and IV, but not of waves V and VI. The results support the notion that the FFR and the BER reflect different mechanisms. Moreover the results do not favor the common hypothesis that the inferior colliculus is the major source of the scalp-recorded human FFR, but rather point to lower brainstem levels.