Ergonomic Optimization of Assembly Workstations: Effects on Productivity and Mental Workload

Event Abstract Back to Event Older brains are not all alike: Individual differences in brain activation patterns during working memory performance Ulman Lindenberger1* 1 Max Planck Institute for Human Development, Germany Individual differences in cognitive performance increase from early to late adulthood. In this talk, I will examine this heterogeneity at genetic and neural levels of analysis. First, I will present the hypothesis that losses in neurochemical and anatomical brain resources in normal aging modulate the effects of common genetic variations on cognitive functioning. This hypothesis is based on the assumption that the function relating brain resources to cognition is nonlinear, so that genetic differences exert increasingly large effects on cognition as resources recede from high to medium levels in the course of aging. I will present empirical support for this hypothesis involving the effects of the COMT and BDNF genes on working memory and episodic memory. Second, I will note that performance heterogeneity generally has been largely neglected in fMRI aging studies of working memory. As a result, age differences in activation patterns are often confounded with individual differences in performance level. I will report data from two studies addressing this issue by comparing younger and older adults whose working memory performance is either low or high. In the first study (Nagel et al., 2009), 30 younger (20-30 years) and 30 older (60-70 years) healthy adults were tested on a spatial WM task with three load levels. In both age groups, a region-of-interest (ROI) analysis revealed marked differences in the activation patterns between high and low performers. Critically, among the older adults, a more “youth-like” load-dependent modulation of the BOLD signal was associated with higher levels of spatial WM performance. In the second study (Nagel et al., submitted), 30 younger adults (21-31) and 30 older adults (60-71) were tested in a parametric letter n-back task, again with three load levels. Across age groups, individual differences in the WM network’s responsivity to increasing task difficulty were related to individual differences in WM performance, with a more responsive BOLD signal predicting greater WM proficiency. Furthermore, individuals with higher WM performance showed greater change in connectivity between left dorsolateral prefrontal cortex and left premotor cortex with load. The results of both studies underscore the need of taking performance level into account when studying adult age differences in functional brain activation patterns. Our results suggest that a more responsive and connectivity-modulated WM network contributes to higher WM performance, regardless of adult age.

Impulsivity is common in bipolar disorder, especially during mania. Understanding the functional neuroanatomy of response inhibition, one component of impulsivity, might clarify the neural substrate of bipolar disorder. Sixteen DSM-IV first-episode, manic bipolar patients and 16 matched healthy subjects were examined during a first manic episode using functional magnetic resonance imaging while performing a response inhibition task. All subjects were studied using a 4.0 Tesla Varian Unity INOVA Whole Body MRI/MRS system. The response inhibition task was presented using non-ferromagnetic goggles, and task performance was recorded during scan acquisition. Imaging data were analysed using analysis of functional neuroimages. Group contrasts were made for the specific response inhibition measure. The groups performed the task similarly, although both demonstrated relatively poor rates of target response, but high rates of successful 'stops'. Despite similar behavioural results, the groups showed significantly different patterns of functional magnetic resonance imaging brain activation. Specifically, during response inhibition, the healthy subjects exhibited significantly greater activation in anterior and posterior cingulate, medial dorsal thalamus, middle temporal gyrus, and precuneus. The bipolar patients exhibited prefrontal activation (BA 10) that was not observed in healthy subjects. Bipolar and healthy subjects exhibit different patterns of brain activation to response inhibition; these differences may reflect different functional neuroanatomic approaches to response inhibition between the two groups.

Athlete or athletic? Limited differential brain activation in person descriptions using nouns or adjectives

In this study we attempted to differentiate distinct components of the saccade network, namely cortical ocular motor centers and parieto-occipital brain regions, by means of a "minimal design" approach. Using a blocked design fMRI paradigm we evaluated the BOLD changes in a 2 x 2 factorial design experiment which was performed in complete darkness: while looking straight ahead with eyes open (OPEN) or closed (CLOSED) as well as during the execution of self-initiated horizontal to-and-fro saccades with the eyes open (SACCopen) or closed (SACCclosed). Eye movements were monitored outside the scanner via electro-oculography and during scanning using video-oculography. Unintentional eye-drifts did not differ during OPEN and CLOSED and saccade frequencies, and amplitudes did not vary significantly between the two saccade conditions. The main findings of the functional imaging study were as follows: (1) Saccades with eyes open or closed in complete darkness lead to distinct differences in brain activation patterns. (2) A parieto-occipital brain region including the precuneus, superior parietal lobule, posterior part of the intraparietal sulcus (IPS), and cuneus was relatively deactivated during saccades performed with eyes closed but not during saccades with eyes open or when looking straight ahead. This could indicate a preparatory state for updating spatial information, which is active during saccades with eyes open even without actual visual input. The preparatory state is suppressed when the eyes are closed during the saccades. (3) Selected ocular motor areas, not including the parietal eye field (PEF), show a stronger activation during SACCclosed than during SACCopen. The increased effort involved in performing saccades with eyes closed, perhaps due to the unusualness of the task, may be the cause of this increased activation.

FMRI-studies are mostly based on a group study approach, either analyzing one group or comparing multiple groups, or on approaches that correlate brain activation with clinically relevant criteria or behavioral measures. In this study we investigate the potential of fMRI-techniques focusing on individual differences in brain activation within a test-retest reliability context. We employ a single-case analysis approach, which contrasts dyscalculic children with a control group of typically developing children. In a second step, a support-vector machine analysis and cluster analysis techniques served to investigate similarities in multivariate brain activation patterns. Children were confronted with a non-symbolic number comparison and a non-symbolic exact calculation task during fMRI acquisition. Conventional second level group comparison analysis only showed small differences around the angular gyrus bilaterally and the left parieto-occipital sulcus. Analyses based on single-case statistical procedures revealed that developmental dyscalculia is characterized by individual differences predominantly in visual processing areas. Dyscalculic children seemed to compensate for relative under-activation in the primary visual cortex through an upregulation in higher visual areas. However, overlap in deviant activation was low for the dyscalculic children, indicating that developmental dyscalculia is a disorder characterized by heterogeneous brain activation differences. Using support vector machine analysis and cluster analysis, we tried to group dyscalculic and typically developing children according to brain activation. Fronto-parietal systems seem to qualify for a distinction between the two groups. However, this was only effective when reliable brain activations of both tasks were employed simultaneously. Results suggest that deficits in number representation in the visual-parietal cortex get compensated for through finger related aspects of number representation in fronto-parietal cortex. We conclude that dyscalculic children show large individual differences in brain activation patterns. Nonetheless, the majority of dyscalculic children can be differentiated from controls employing brain activation patterns when appropriate methods are used.

On Altered Patterns of Brain Activation in At-Risk Adolescents and Young Adults

The present study utilized functional near infrared spectroscopy (fNIRS) to detect neural activation differences in the orbitofrontal brain region between individuals with multiple sclerosis (MS) and healthy controls (HCs) during a working memory (WM) task. Thirteen individuals with MS and 12 HCs underwent fNIRS recording while performing the n-back WM task with four levels of difficulty (0-, 1-, 2-, and 3-back). Subjects were fitted with the fNIRS cap consisting of 30 'optodes' positioned over the forehead. The results revealed different patterns of brain activation in MS and HCs. The MS group showed an increase in brain activation, as measured by the concentration of oxygenated hemoglobin (oxyHb), in the left superior frontal gyrus (LSFG) at lower task difficulty levels (i.e. 1-back), followed by a decrease at higher task difficulty (2- and 3-back) as compared with the HC group. HC group achieved higher accuracy than the MS group on the lower task loads (i.e. 0- and 1-back), however there were no performance differences between the groups at the higher task loads (i.e. 2- and 3-back). Taken together, the results suggest that individuals with MS experience a task with the lower cognitive load as more difficult than the HC group, and the brain activation patterns observed during the task confirm some of the previous findings from functional magnetic resonance imaging (fMRI) studies. This study is the first to investigate brain activation by utilizing the method of fNIRS in MS during the performance of a cognitive task.

Different patterns of brain activity are observed in various subjects across a wide functional domain. However, these individual differences, which are often neglected through the group average, are not yet completely understood. Based on the fundamental assumption that human behavior is rooted in the underlying brain function, we speculated that the individual differences in brain activity are reflected in the individual differences in behavior. Adopting 98 behavioral measures and assessing the brain activity induced at seven task functional magnetic resonance imaging states, we demonstrated that the individual differences in brain activity can be used to predict behavioral measures of individual subjects with high accuracy using the partial least square regression model. In addition, we revealed that behavior-relevant individual differences in brain activity transferred between different task states and can be used to reconstruct individual brain activity. Reconstructed individual brain activity retained certain individual differences which were lost in the group average and could serve as an individual functional localizer. Therefore, our results suggest that the individual differences in brain activity contain behavior-relevant information and should be included in group averaging. Moreover, reconstructed individual brain activity shows a potential use in precise and personalized medicine.

Children with developmental coordination disorder (DCD) struggle to learn new motor skills, demonstrating more variable performance than typically developing (TD) children. The purpose of this study was to determine whether patterns of brain activity differed between children with and without DCD while performing a motor task. Using functional MRI, we measured brain activation patterns in 7 children with DCD and 7 age-matched peers (aged 8-12 years) during a fine-motor, trail-tracing task. Despite similar levels of behavioral motor performance, different patterns of brain activity were noted between the 2 groups. The group with DCD showed significantly more activation than control subjects in left inferior parietal lobule, right middle frontal gyrus, right supramarginal gyrus, right lingual gyrus, right parahippocampal gyrus, right posterior cingulate gyrus, right precentral gyrus, right superior temporal gyrus, and right cerebellar lobule VI. These results suggest that the group with DCD relied on visuospatial processing to complete the task. The TD group demonstrated significantly more activation than the group with DCD in left precuneus, left superior frontal gyrus, right superior temporal gyrus/insula, left inferior frontal gyrus, and left postcentral gyrus; these regions have been associated with spatial processing, motor control and learning, and error processing. Children with DCD activate different brain regions from typical children when performing the same trail-tracing task. Despite the small sample size, our results contribute to a growing body of literature suggesting that children with DCD exhibit differences in neural networks and patterns of brain activation relative to same-age peers.

The simultaneous performance of multiple tasks is often required in daily life. The dual-task paradigm has been used extensively to evaluate the ability to perform simultaneous behavioral tasks. However, relatively few studies have been carried out to determine the muscle and brain activity underlying dual-task performance. This study determined the influence of single-task and dual-task conditions on muscle and brain activity by measuring ankle dorsiflexion, surface electromyography, and magnetoencephalography. Increased muscle activation and variability in the dorsiflexion interval was observed during dual-task performance compared with single-task performance, whereas brain activity in the contralateral motor and frontal areas was reduced. Incidental movement of the non-task-related ankle (contralateral ankle) showed a different pattern of brain activity during the dual-task performance in another experiment. These findings suggest that the activity decreased in several information-processing areas under dual-task conditions as a result of decentralization of attention. Activity in the right and left motor fields may play a role in the dual-task performance, as indicated by changes in brain activity during dual-task performance in two groups classified according to the activity level of the contralateral ankle.

The differences in brain mechanisms that underlie the switch between involuntary and voluntary attention associated with gender were investigated. We compared reaction time, the number of errors and the electrical activity of the brain during the Emotional Stroop test on the background of visual content that contained affective images when presenting stimuli through a dominant and non-dominant eye in 20 men and 20 women. The model of significant cognitive load was created, when it is quite difficult to correctly respond to the relevant characteristics of the stimulus. Different patterns of brain activity have been found: in women, this task is accompanied by an increase in spectral power in the theta range of the predominantly left hemisphere; in men, the power of alpha rhythm in the parietal-occipital associative cortex decreases with the local increase of theta rhythm in the posterior-frontal areas and beta-rhythm in left prefrontal zone. Under the conditions of high cognitive load created by the distracting visual content and the perception of visual stimuli through the non-dominant eye, the brain mechanisms of voluntary attention provide a more thorough analysis of the relevant stimuli in women that is seen in accurate responses over a longer period in comparison with men.

BackgroundAutism is a neurodevelopmental disorder, and there are certain differences in the brain activation patterns of English language semantic processing among autistic individuals. The research aims to explore the brain activation patterns of autistic groups during English semantic processing thus to enhance their understanding of language development.Subjects and MethodsThe study used functional Magnetic Resonance Imaging (fMRI) technology, combined with the task paradigm of English word meaning processing, to study the brain activation patterns of individuals with autism. By comparing the differences in brain activation patterns between two groups in word meaning processing tasks, researchers attempted to reveal the specific neural mechanisms involved in language processing in autistic groups. At the same time, SPSS23.0 statistical software was used to process the data.ResultsThrough comparative experiments, the Hamilton Anxiety Rating Scale (HAMA) score and Generalized Self-Efficacy Scale (GSES) score of the experimental group were 7.53 and 31.24 respectively; The HAMA and GSES scores of the control group were 10.84 and 25.81, respectively. The results indicate that the processing of English language word meanings has a brain activation effect on people with autism.Conclusions Research can promote the understanding of the cognitive and neural mechanisms of autism, and contribute to improving daily communication and life quality for autistic groups.AcknowledgementThe Education Department of Hainan Province (No. Hnjgzc2022-121); The Education Department of Hainan Province (No. Hnjgw2022-13).

Objective: This study aimed to compare the regulation of brain activity by different kinds of long-term exercises (Tai Chi, treadmill training, and dancing) in healthy older adults and those with PD. Methods: From January 2000 to October 2021, the electronic databases PubMed, Web of Science, and Scopus were searched. All articles were screened throughout the inclusion and exclusion criteria, which was followed by PICOS criteria. Finally, all articles were systematically reviewed with analyses. Results: 29 studies were identified for this review, 24 of which were finally included in a group of healthy older adults, and five of which in a group of people with PD. All studies showed that significant changes were showed on people with PD and healthy older adults' brain activity after three terms of the exercises we chose. An inverse change trend on the functional connectivity in people with PD was observed after treadmill training, whereas increased brain activity, cognitive function, memory, and emotion were noticed in healthy older adults. Conclusion: Our findings suggest that different patterns of brain activity were also observed between healthy older adults and people with PD after treadmill training. However, more robust evidence and comprehensive studies are needed to determine if there is a difference between healthy older adults and people with PD.

BackgroundExecutive function is vital for cognitive health, particularly in older adults, where declines can lead to an increased risk of cognitive impairment. Physical activity (PA) has been linked to improvements in executive function, yet the underlying mechanisms remain poorly understood.MethodsThis cross-sectional study involved 41 Chinese adults (21 young: 23.0 ± 2.12 years; 20 older: 63.30 ± 2.36 years) who were categorized as physically active (≥3000 metabolic equivalent (MET)-min/week) or inactive (<3000 MET-min/week). Participants performed fMRI while completing executive function tasks (Flanker, N-back, Switching). Brain activation patterns were analyzed using Statistical Parametric Mapping (SPM), with significance thresholds set at p < 0.01 (voxel-level) and p < 0.05 (whole-brain corrected).ResultsPhysically active older adults showed significantly better accuracy and faster reaction times on the Flanker task than inactive peers. In young adults, those who were inactive exhibited greater activation in prefrontal regions during executive tasks. No significant differences in brain activation were found in older adults for these tasks. Additionally, activation in the right medial/paracentral cingulate gyrus (BA 6) negatively correlated with working memory reaction times in active young adults (r= −0.804, p < 0.05), whereas cognitive flexibility in active older adults positively correlated with activation in the right dorsolateral frontal gyrus (BA 32; r = 0.589, p < 0.05).ConclusionActive older adults require less brain activation to perform executive function tasks, suggesting enhanced cognitive efficiency. In contrast, young adults showed different patterns of brain activation, indicating potential compensatory mechanisms. These results underscore PA’s role in optimizing age-specific cognitive strategies and underscore the need for longitudinal research to clarify causality.

Background: Theory of mind (ToM) functioning develops during certain phases of childhood. Factors such as language development and educational style seem to influence its development. Some studies that have focused on transcultural aspects of ToM development have found differences between Asian and Western cultures. To date, however, little is known about transcultural differences in neural activation patterns as they relate to ToM functioning. Experimental methods: The aim of our study was to observe ToM functioning and differences in brain activation patterns, as assessed by functional magnetic resonance imaging (fMRI). This study included a sample of 18 healthy Japanese and 15 healthy Caucasian subjects living in Japan. We presented a ToM task depicting geometrical shapes moving in social patterns. We also administered questionnaires to examine empathy abilities and cultural background factors. Results: Behavioral data showed no significant group differences in the subjects' post-scan descriptions of the movies. The imaging results displayed stronger activation in the medial prefrontal cortex (MPFC) in the Caucasian sample during the presentation of ToM videos. Furthermore, the task-associated activation of the MPFC was positively correlated with autistic and alexithymic features in the Japanese sample. Discussion: In summary, our results showed evidence of culturally dependent sociobehavioral trait patterns, which suggests that they have an impact on brain activation patterns during information processing involving ToM.