Sergei A. Schapkin

Effects of aging and job demands on cognitive flexibility assessed by task switching.

In a cross-sectional, electrophysiological study 91 workers of a big car factory performed a series of switch tasks to assess their cognitive control functions. Four groups of workers participated in the study: 23 young and 23 middle aged assembly line employees and 22 young and 23 middle aged employees with flexible job demands like service and maintenance. Participants performed three digit categorisation tasks. In addition to single task blocks, a cue-based (externally guided) and a memory-based (internally guided) task switch block was administered. Compared to young participants, older ones showed the typical RT-decline. No differences between younger and older participants regarding the local switch costs could be detected despite the source of the current task information. In contrast, whereas the groups did not differ in mixing costs in the cued condition, clear performance decrements in the memory-based mixing block were observed in the group of older employees with repetitive work demands. These findings were corroborated by a number of electrophysiological results showing a reduced CNV suggesting an impairment of task specific preparation, an attenuated P3b suggesting reduced working memory capacity and a decreased Ne suggesting deficits in error monitoring in older participants with repetitive job demands. The results are compatible with the assumption that long lasting, unchallenging job demands may induce several neurocognitive impairments which are already evident in the early fifties. Longitudinal studies are needed to confirm this assumption.

PRACTICE-RELATED EFFECTS IN A GO-NOGO TASK '

Comparison of an incoming stimulus with a memory template and the inhibition of an irrelevant response representation assumes these are separable processes differently affected by practice. Practice effects were studied in a visual Go-Nogo task which contained stimuli either compatible or incompatible with a response. Eight participants (19–28 years old, M = 23.3, SD = 3.6) performed the task with simultaneous EEG recording every morning during three consecutive weeks except weekends. Short-term, long-term, as well as weekday effects were analyzed. As a short-term effect, the false alarm rate became smaller; this was accompanied by an enhancement of the frontal N2 component of the event-related potential (ERP). As a long-term effect, the shortening of reaction time to incompatible stimuli and increase of the blink rate for Go trials was observed. Within the N2 two subcomponents, the early (N2e) and late (N2l) could be distinguished. N2e and N2l varied differently with the experimental manipulations. First, they showed different effects of stimulus compatibility. Second, the N2e was enhanced with practice irrespective of trial type, while the practice-related increase of the N2l was obtained for Nogo trials only. Third, the practice-related effects on components differed in scalp topography. The results suggest N2e reflects the comparison process and N2l the inhibition of an irrelevant response representation. Both processes improved with practice.

Noise Aftereffects and Brain Processes Mediating Role of Achievement Motivation

Abstract. Aftereffects of noise-induced sleep disturbance on executive functions were investigated with motivational traits as mediating variables. Thirty-two healthy young subjects performed a visual Go/Nogo task with simultaneous EEG recording after a quiet night and after 3 nights with railway noise at different noise levels. As motivational traits, the “hope of success” (HS) and “fear of failure” (FF) were assessed. Subjective sleep rating worsened with increased noise level, but, noise-induced sleep disturbances did not affect performance immediately following sleep. However, in the event-related potential (ERP) an attenuation of the N2 and P3 amplitude as well as an increase in N2 latency in Noise conditions were found. Only subjects who scored low in HS showed a reduction of the N2 after Noise, while subjects who scored high in HS did not. The N2 and P3 were larger in high HS than in low HS subjects in Nogo trials only. Similarly, low FF subjects had larger N2 and P3 than high FF subjects in Nogo t...

Impaired Error Processing and Semantic Processing During Multitasking

Neuronal mechanisms of error processing under multitasking and their impact on the processing of a concurrent task were examined. Twenty-one younger and twenty older healthy adults performed a visual-motor flanker task or an auditory-vocal semantic task or both tasks simultaneously. During task performance the electroencephalogram (EEG) was continuously recorded. The event-related potential (ERP) was derived from the EEG, and ERP components associated with error processing (Ne and Pe) and semantic processing (N400) were analyzed. Older participants responded more slowly than younger ones in the flanker task regardless of the multitasking condition, while accuracy was equal in both groups. In the flanker task, multitasking led to an increase of error rates, a reduction of reaction times, and a disappearance of post-error slowing (PES). Error detection (Ne) was delayed and error awareness (Pe) attenuated in the single flanker task relative to the multitasking condition. In the semantic task, multitasking led to an increase of reaction times and a delay of the N400 in particular when an error in the flanker task occurred. First, these results indicate that multitasking impaired error processing, in particular conscious error perception (Pe) and abolished post-error adjustments of performance (PES) which may have resulted in a more risky response tendency in the flanker task. Second, multitasking impaired semantic processing, in particular after an error in the concurrent flanker task. Hence, multitasking compromised error processing and error prevention in one of the tasks, and semantic processing in the other task. Consequently, multitasking should be avoided at workplaces with error-prone job assignments or where poor understanding of communication may have serious consequences.

Stress and managers performance: age-related changes in psychophysiological reactions to cognitive load

Work ability of elderly managers may decrease probably due to decreased cognitive flexibility. Moreover, cardiovascular reactivity to changing task demands might be less efficient in elderly. Younger (36-45) and elderly (49-60) German managers had to perform a switching task when they had to switch continuously between different rules of information processing or to use the same rule. Although the performance did not differ between groups, the SBP was higher and the HRV was lower in elderly. In addition, elderly showed an increased rigidity of cardiovascular functioning against changing task demands.

Neuronal Mechanisms of Working Memory Performance in Younger and Older Employees

As working memory WM is compromised with advancing age, older people may have performance deficits in WM tasks. This is probably due to a great number of WM operations which should be performed for extended periods of time. The reduction of a number of these operations was expected to reduce WM load and age-related deficits in WM performance. Fifty younger 29±3 years and 49 older 55±3 years healthy employees had to perform a visual 0-back oddball task and a 2-back task. Within the 2-back task, the short 3 or 4 items, low WM load and long 5 or 6 items, high WM load target-to-target sub-sequences were analysed separately. Older workers performed worse than younger ones at higher WM loads, except for the oddball condition and low WM load condition. The N2 latency of the event-related potentials ERPs increased with WM load and was generally longer in older than younger adults. In addition, the N2 latency decreased with WM load in younger adults but did not change in older ones. Older workers also showed a delayed P3a as well as a delayed and reduced P3b. By contrast, age-related enhancements of the occipital N1 and frontal P2 components under WM load were observed. The parietal slow positive wave SPW increased under high WM load but did not vary with age. The results indicate that older adults are able to compensate for age-related WM impairments when the amount of WM operations required does not exceed the limits of their WM capacity. The allocation of cognitive resources to stimulus encoding N1 and memory retrieval P2 are putative neuronal mechanisms for these WM improvements. However, older adults have maintenance problems at higher WM loads. This is associated with deficits in neuronal processes relating to response selection N2, detection of changes in WM representations P3a and WM updating P3b. These results provide a basis for the development of work load criteria and training opportunities for older workers who have to do complex work requiring working memory.

Test battery for assessment of cognitive function in older employees: performance, brain processes, and cardiovascular "costs"

Declines in cognitive function with advancing age may cause performance decrements and stress in older workers who have to do complex work. We aimed to develop a system for complex assessment of cognitive load in older employees with parallel registration of behavioural, neuronal and cardiovascular activity. We present the test battery that can provide reliable data on age-related cognitive deficits. Using this test battery, EEG and cardiovascular indexes were found which are stable over time, sensitive to ageing and cognitive load. The test battery and physiological indexes are suitable for the development of a computational model describing heart-brain interactions during work performance. The model may be further implemented into mobile devices using for the online assessment of cognitive load.