Evaluation of a non-auditory neurocognitive test battery in hearing-impaired according to age.

PURPOSE: Due to the demographic shift, the number of older people suffering from hearing loss and from cognitive impairment increases. Both are closely related and hard to differentiate as most standard cognitive test batteries are auditory-based and hearing-impaired individuals perform worse also in non-auditory test batteries. Therefore, reference data for hearing-impaired are mandatory. METHODS: The computer-based battery ALAcog assesses multiple cognitive domains, such as attention, (delayed) memory, working memory, inhibition, processing speed, mental flexibility and verbal fluency. A data set of 201 bilaterally hearing-impaired subjects aged ≥ 50 (mean 66.6 (SD 9.07)) was analysed. The LMS method, estimated curves for the 10th, 25th, 50th, 75th and 90th percentile were calculated, and classified according to age, starting from the age of 50. RESULTS: Cognitive function shows a decline in all subtests as people age, except for verbal fluency, which remains almost stable over age. The greatest declines were seen in recall and delayed recall and in mental flexibility. Age and hearing ability did not correlate (p = 0.68). However, as people age, inter-subject variability of cognitive test results increases. This was especially the case for inhibition. Cognitive function was not correlated with hearing ability (each p ≥ 0.13). CONCLUSION: The present results make an approach to establish reference data for a comprehensive non-auditory test battery in a large sample of elderly hearing-impaired people which can be used as a simple tool to better contextualise cognitive performance beyond mean and median scores.

ERP indices for response inhibition are related to anxiety-related personality traits.

Anxiety is often associated with impaired cognitive control and avoidance behaviour. The aim of this study was to investigate the effect of anxiety-related personality traits, such as anxiety sensitivity and trait anxiety, on event-related potentials of response inhibition in a standard Go/Nogo-paradigm. We focused on the Nogo-N2 and Nogo-P3 components, which probably represent different sub-processes of response inhibition. The Nogo-N2 was mainly influenced by trait anxiety, while it was slightly affected by anxiety sensitivity. In contrast, the Nogo-P3 was significantly associated with anxiety sensitivity, but was less affected by trait anxiety. Thus, anxious subjects seem to maintain a higher level of cognitive control to prepare and to monitor the outcome of their actions, which is differentially reflected in Nogo-N2 and Nogo-P3 potentials. Our results show that anxiety-related personality traits modulate electrophysiological responses related to cognitive control processes and should be taken into consideration in studies investigating response inhibition.

Paradoxical association of the brain-derived-neurotrophic-factor val66met genotype with response inhibition.

Response inhibition is a basic executive function which is dysfunctional in various basal ganglia diseases. The brain-derived-neurotrophic-factor (BDNF) plays an important pathophysiological role in these diseases. In the current study we examined the functional relevance of the BDNF val66met polymorphism for response inhibition processes in 57 healthy human subjects using event-related potentials (ERPs), i.e. the Nogo-N2 and Nogo-P3, which likely reflect different aspects of inhibition. Our results support the pre-motor inhibition theory of the Nogo-N2. We show that the BDNF val66met polymorphism selectively modulates the Nogo-N2. Response inhibition was better in the val/met-met/met group, since this group committed fewer false alarms, and their Nogo-N2 was larger, compared to the val/val group. This is the first study showing that met alleles of the BDNF val66met polymorphism confer an advantage for a specific cognitive function. We propose a neuronal model how this advantage gets manifest on a neuronal level.

[Cognitive competence of older workers]. / Kognitive Leistungsfähigkeit älterer Arbeitnehmer.

The article provides a short overview on cognitive strengths and weaknesses of older workers. The older people who are under the age of 65 years already exhibit changes in performance and neurophysiological measures in laboratory tasks that test fluid intelligence. Apart from deficits, the physiological data of the older people show clear evidence for compensatory strategies. Cognitive performance on the current job is usually less impaired. This can be explained by practice, learning, and selection, which are, however, often linked with higher effort. The cognitive competence of older employees varies exorbitantly, which is due to the influence of various factors like education, lifestyle, and in particular the type of work. Thus, the cognitive competence of older employees can be preserved and possibly even enhanced by changes in the work situation as well as by individual training procedures such as cognitive training.

Error processing in normal aging and in basal ganglia disorders.

Recently it has been shown that effects of aging and pathologically induced changes of basal ganglia structures may have quite similar effects on cognitive functions mediated by the medial prefrontal cortex. The question appears, if this pattern may be assignable to other cognitive functions that are mediated via the basal ganglia and medial prefrontal brain areas. Error processing is a component of executive functions that also depends on these areas and especially on the anterior cingulate cortex (ACC). Hence we ask, if error processing functions are differentially modulated by normal aging and basal ganglia diseases. Error processing mechanisms in these groups were investigated using a cognitive event-related potential (ERP), the error negativity. Enrolling an extended sample of young and elderly controls, as well as patients with Parkinson's and Huntington's disease, we show that modulations of error processing differ between aging, different basal ganglia diseases. Despite that the examined basal ganglia disorder groups (Parkinson's and Huntington's disease) differ in their age they show similar modulations in error processing, suggesting that aging effects are overridden by pathogenic effects. The study shows that it may be valuable to compare aging not only to different forms of basal ganglia disorders in order to gain knowledge about age- and disease-related mechanisms and the effects of these on cognitive functions. Diseases of the basal ganglia may impact error processing above and beyond the effects of normal aging. Although many aging, Parkinson's disease and Huntington's disease studies on error processing functions have already been published, this study ties together several related observations across all of these groups in one experiment.

Error processing in patients with Parkinson's disease: the influence of medication state.

One of the hallmarks of Parkinson's disease (PD) is a depletion of dopamine. Error processing, as reflected in a component of the event-related potential, the so-called error (related) negativity (Ne or ERN) is likely dependent on the midbrain dopaminergic system. In case of an unfavourable event such as an error, this system is assumed to send an error signal to the mediofrontal cortex, which elicits the Ne. Hence, the Ne should be altered in patients with PD. In fact, we earlier found a reduction of the Ne in medicated patients with PD in different tasks while another group found no such reduction in "off-medication" patients in a flanker task. In the present study, we reinvestigated this issue by measuring the Ne in a large group of treated PD patients in the "on"- and "off"-parkinsonian medication state and in matched control subjects in a flanker task. The Ne was found to be the same in the "on-medication" and "off-medication" state, while the motor score in the Unified Parkinson's Disease Rating Scale was different. In both medication states the Ne was smaller in the patients than in the controls. The results show that the Ne reduction found earlier is unaffected by short-term differences in parkinsonian medication. The question remains open whether the long-term medication could have contributed to the Ne reduction.

Response inhibition in borderline personality disorder: event-related potentials in a Go/Nogo task.

Borderline personality disorder (BPD) has been related to a dysfunction of anterior cingulate cortex, amygdala, and prefrontal cortex and has been associated clinically with impulsivity, affective instability, and significant interpersonal distress. We examined 17 patients with BPD and 17 age-, sex-, and education matched control participants with no history of Axis I or II psychopathology using event-related potentials (ERPs). Participants performed a hybrid flanker-Go/Nogo task while multichannel EEG was recorded. Our study focused on two ERP components: the Nogo-N2 and the Nogo-P3, which have been discussed in the context of response inhibition and response conflict. ERPs were computed on correct Go trials (button press) and correct Nogo trials (no button press), separately. Groups did not differ with regard to the Nogo-N2. However, BPD patients showed reduced Nogo-P3 amplitudes. For the entire group (n = 34) we found a negative correlation with the Barratt Impulsiveness Scale (BIS-10) and Becks's depression inventory (BDI). The present study is the first to examine Nogo-N2 and Nogo-P3 in BPD and provides further evidence for impaired response inhibition in BPD patients.

Executive control in obsessive-compulsive disorder: event-related potentials in a Go/Nogo task.

Obsessive-compulsive disorder (OCD) has been related to a hyperactive cortico-striatal-pallidal-thalamic circuitry resulting clinically in an impaired inhibition of repetitive thoughts and behaviors. We examined thirteen patients with OCD and thirteen age-, sex-, and education matched healthy controls using event-related potentials (ERPs). Participants performed a hybrid flanker-Go/Nogo task while multichannel EEG was recorded. Our study focused on two ERP components: the Nogo-N2 and the Nogo-P3, which have been discussed in the context of response inhibition and response conflict. Artifact-free EEG-segments were used to compute ERPs on correct Go trials (button press) and correct Nogo trials (no button press), separately. Patients with OCD showed enhanced (more negative) Nogo-N2 amplitudes than controls, and a significant difference in amplitudes between Nogo-N2 and Go-N2 trials (more negative for Nogo trials) at central midline electrode positions. However, groups did not differ with regard to the Nogo-P3 and Go-P3. The present study replicates and extends previous findings of altered executive control processes in OCD patients.

Effects of stimulus-response compatibility in Parkinson's disease: a psychophysiological analysis.

The present study investigated the mechanisms underlying stimulus-response compatibility effects in Parkinson's disease patients and matched controls. Since basal ganglia are involved in the selection and inhibition of competing responses we examined whether basal ganglia dysfunction in Parkinson's disease leads to greater interference effects compared to the control subjects. Reaction times and lateralized movement-related cortical potentials (lateralized readiness potential: LRP) were recorded in two modified Eriksen flanker tasks. Both groups were influenced by compatibility conditions; interference was seen as enhanced reaction time and error rate, as well as incorrect early LRP and delayed late LRP in incongruent trials. Altogether, behavioral and electrophysiological measures showed the interference to be rather smaller for the patients than for the controls. In contrast, facilitation did not differ among groups. Hence the claim that Parkinson's disease patients are more influenced than controls by interfering directional stimuli appears not always valid.

Auditory distraction in young and middle-aged adults: a behavioural and event-related potential study.

Cognitive tasks involving distraction are associated with an early age-related decline in performance. Involuntary shifts in attention to irrelevant stimulus features and subsequent reorientation were studied in young and middle-aged subjects focussing on behavioural and event-related potential (ERP) measures. Subjects were asked to discriminate between equiprobable short and long auditory stimuli. Irrelevant rare frequency deviations prolonged reaction times (RT's), while an age-related effect on RT's was not observed. In contrast, notably after short deviant tones the error rate was considerably increased in the middle-aged subjects. ERP measures after deviant stimuli elicited a sequence of mismatch negativity (MMN), P3a and reorienting negativity (RON). The latency and amplitude of the MMN did not differ between age groups indicating an unchanged deviance detection. However, the consecutive process of attention orientation (P3a) was delayed and the subsequent reorienting (RON) to the primary task was strongly attenuated in the middle-aged subjects. After short deviants the RON was virtually absent in the middle-aged subjects, which might account for the observed decline of accuracy.

Changes of error-related ERPs with age.

Errors in reaction tasks are followed by a negative component of the event-related brain potential (ERP), the error negativity (Ne), which is thought to be a correlate of error detection. In the present study we show that, in tasks that induce different types of errors, the amplitude of the Ne was reduced in elderly (54-65 years old) compared with young subjects (19-25 years old). This reduction was also seen in single trials, as were computed for one of the visual tasks. Moreover, in this data set, the single-trial Ne was also delayed for the elderly compared with the young. These data suggest an alteration of error detection in the elderly, which is only marginally reflected in performance.

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 Parkinson's 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.

Early attention effects in human auditory-evoked potentials.

A fundamental question in attention theory concerns the earliest processing stages that can be modulated by selective attention. A series of experiments is reported in which very early attention effects are found under specific conditions in the frequency-following potential (FFP), a brain stem response to low-frequency tone stimuli. In two experiments, stimuli of two different modalities were applied, and attention directed to one of the modalities. In two further experiments, only auditory stimuli were presented. In the first of these last two experiments, a dichotic paradigm with sustained attention to one ear was used, in the second a monotic paired-stimuli paradigm was used, in which the first stimulus served as reference for the second one. Only in the last experiment significant attention effects were found in the latency, but not in the amplitude of the FFP. The results show that a very early attention effect on the latency of the FFP can be demonstrated, but only under highly specific conditions. The size and preconditions of the attention effect suggest that it reflects subtle intramodal tuning mechanisms in the cochlea or in the lower brain stem.

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.

Different error types and error processing in spatial stimulus-response-compatibility tasks: behavioural and electrophysiological data.

We tested the hypothesis that in spatial stimulus-response-compatibility (SRC) tasks two different error types occur: A noise-induced 'general error' independent of SRC and reaction time and a 'position driven error' in incompatible trials with short RT being driven by the irrelevant stimulus position. A second issue was whether error detection is different for these two types of errors, which should be reflected by differences in the error negativity (Ne), since the Ne is seen as a neural correlate of error detection. To study these issues, we used a Simon- and a spatial Stroop-task. In incompatible (vs. compatible) trials we found more errors and a below chance accuracy in fast responses. Neither the amplitude nor the latency of the Ne were significantly affected by the experimental factors. This pattern of behavioural results supports the above hypothesis of two error types in such tasks. The Ne results indicate that error detection is similar for both types of errors.

ERP components in Go/Nogo tasks and their relation to inhibition.

In visual Go/Nogo tasks the ERP usually shows a frontal negativity after Nogo stimuli ("Nogo-N2"), which possibly reflects an inhibition process. However, the Nogo-N2 appears to be very small after auditory stimuli, which is evidence against the inhibition hypothesis. In the present study we tested this hypothesis by evaluating performance differences between subjects. Assuming that for Ss with a high false alarm rate the inhibition process is weakened and/or delayed, they should reveal a smaller and/or later Nogo-N2 than Ss with a low false alarm rate. This prediction was confirmed, which supports the inhibition hypothesis. However, the Nogo-N2 was again much smaller and had a different topography after auditory than after visual stimuli despite similar performance in both modalities. This modality asymmetry was explained by assuming that the inhibitory mechanism reflected in the Nogo-N2 is located at a pre-motor rather than at the motor level. In the second part of the study we compared the Nogo-N2 with a similar phenomenon, the error negativity (Ne), which occurs in trials with commission errors (false alarms). Earlier work suggests that the Ne is a correlate of error detection or inhibition. This raises the possibility that the Ne is a delayed Nogo-N2, i.e., the Ne may reflect a late and hence unsuccessful attempt to inhibit the response after a nontarget. However, the Ne amplitude showed no difference between performance groups and stimulus modalities, as found for the Nogo-N2. Moreover, Ne and Nogo-N2 had different scalp topographies. This suggests that different mechanisms and generators underlie the Ne and the Nogo-N2.

Performance differences in reaction tasks are reflected in event-related brain potentials (ERPs).

Event-related potentials (ERPs), which can be extracted from the electroencephalogram (EEG), are assumed to reflect distinct cognitive processes in real time. Hence ERP analysis could be used in cognitive ergonomics as a tool to specify, for example, bottlenecks or sources of individual performance differences. Such specific results may be helpful to change the tasks or train the subjects specifically. In the present exploratory study, the authors investigated whether subjects with large spontaneous differences in performance accuracy, as defined by their error rates in a speeded binary choice reaction task, also differ in the structure of their ERPs. The ten subjects were divided post hoc into two groups with relatively low (about 6%) and high (about 20%) error rates. While the reaction times were not significantly different for both groups, the ERPs revealed clear group differences. First, large differences were seen in the late part of the contingent negative variation (late CNV), which is assumed to reflect preparatory processes. Subjects with few errors ('GOOD') had a large late CNV, while subjects with many errors ('POOR') showed virtually no late CNV. Second, the late P300-subcomponent (which is related to response identification) was smaller and delayed for POOR compared to GOOD subjects. Finally, the ERP shows signs of poor movement control in POOR subjects. The high error rate of POOR subjects can hence be explained by: (1) their insufficient preparation for the next trial (small late CNV), which impaired response identification (small and delayed late P300 subcomponent); and (2) their poor movement control. These interpretations have to be regarded as preliminary and should be validated with larger groups of subjects. In conclusion, the main reasons for the profound performance differences between the groups, namely differential preparation and movement control, could be elucidated by ERP analysis. A potential ergonomics application of these results is that they suggest specific strategies (for example, a preparation and motor control training) to improve the performance of POOR subjects in comparable work conditions.

A method to improve the latency estimation of the frequency-following potential (FFP).

If the latency of a noisy frequency-following potential (FFP) is estimated by determining the shift of the (periodical) cross-correlation function (CCF) between the stimulus and the FFP, the result may be unambiguous only within +/-1 or +/-2 periods of the CCF, because the absolute maximum and adjacent local maxima may not be significantly different. Here we present a method to amplify this difference by applying amplitude modulated stimuli. Using this method we first illustrate the effect of the method by a simulation and then demonstrate its usefulness by measuring real FFPs and estimating their latencies.