@article{HortobagyiUematsuSandersetal.2018, author = {Hortobagyi, Tibor and Uematsu, Azusa and Sanders, Lianne and Kliegl, Reinhold and Tollar, Jozsef and Moraes, Renato and Granacher, Urs}, title = {Beam Walking to Assess Dynamic Balance in Health and Disease}, series = {Gerontology}, volume = {65}, journal = {Gerontology}, number = {4}, publisher = {Karger}, address = {Basel}, issn = {0304-324X}, doi = {10.1159/000493360}, pages = {332 -- 339}, year = {2018}, abstract = {Background: Dynamic balance keeps the vertical projection of the center of mass within the base of support while walking. Dynamic balance tests are used to predict the risks of falls and eventual falls. The psychometric properties of most dynamic balance tests are unsatisfactory and do not comprise an actual loss of balance while walking. Objectives: Using beam walking distance as a measure of dynamic balance, the BEAM consortium will determine the psychometric properties, lifespan and patient reference values, the relationship with selected "dynamic balance tests," and the accuracy of beam walking distance to predict falls. Methods: This cross-sectional observational study will examine healthy adults in 7 decades (n = 432) at 4 centers. Center 5 will examine patients (n = 100) diagnosed with Parkinson's disease, multiple sclerosis, stroke, and balance disorders. In test 1, all participants will be measured for demographics, medical history, muscle strength, gait, static balance, dynamic balance using beam walking under single (beam walking only) and dual task conditions (beam walking while concurrently performing an arithmetic task), and several cognitive functions. Patients and healthy participants age 50 years or older will be additionally measured for fear of falling, history of falls, miniBESTest, functional reach on a force platform, timed up and go, and reactive balance. All participants age 50 years or older will be recalled to report fear of falling and fall history 6 and 12 months after test 1. In test 2, seven to ten days after test 1, healthy young adults and age 50 years or older (n = 40) will be retested for reliability of beam walking performance. Conclusion: We expect to find that beam walking performance vis-{\`a}-vis the traditionally used balance outcomes predicts more accurately fall risks and falls. Clinical Trial Registration Number: NCT03532984.}, language = {en} } @article{HeinzelLorenzQuynhLamDuongetal.2017, author = {Heinzel, Stephan and Lorenz, Robert C. and Quynh-Lam Duong, and Rapp, Michael A. and Deserno, Lorenz}, title = {Prefrontal-parietal effective connectivity during working memory in older adults}, series = {Neurobiology of Aging}, volume = {57}, journal = {Neurobiology of Aging}, publisher = {Elsevier}, address = {New York}, issn = {0197-4580}, doi = {10.1016/j.neurobiolaging.2017.05.005}, pages = {18 -- 27}, year = {2017}, abstract = {Theoretical models and preceding studies have described age-related alterations in neuronal activation of frontoparietal regions in a working memory (WM)load-dependent manner. However, to date, underlying neuronal mechanisms of these WM load-dependent activation changes in aging remain poorly understood. The aim of this study was to investigate these mechanisms in terms of effective connectivity by application of dynamic causal modeling with Bayesian Model Selection. Eighteen healthy younger (age: 20-32 years) and 32 older (60-75 years) participants performed an n-back task with 3 WM load levels during functional magnetic resonance imaging (fMRI). Behavioral and conventional fMRI results replicated age group by WM load interactions. Importantly, the analysis of effective connectivity derived from dynamic causal modeling, indicated an age-and performance-related reduction in WM load-dependent modulation of connectivity from dorsolateral prefrontal cortex to inferior parietal lobule. This finding provides evidence for the proposal that age-related WM decline manifests as deficient WM load-dependent modulation of neuronal top-down control and can integrate implications from theoretical models and previous studies of functional changes in the aging brain.}, language = {en} } @article{BeijersbergenHortobagyiBeurskensetal.2016, author = {Beijersbergen, Chantal M. I. and Hortobagyi, Tibor and Beurskens, Rainer and Lenzen-Grossimlinghaus, Romana and Gabler, Martijn and Granacher, Urs}, title = {Effects of Power Training on Mobility and Gait Biomechanics in Old Adults with Moderate Mobility Disability: Protocol and Design of the Potsdam Gait Study (POGS)}, series = {Gerontology}, volume = {62}, journal = {Gerontology}, publisher = {Karger}, address = {Basel}, issn = {0304-324X}, doi = {10.1159/000444752}, pages = {597 -- 603}, year = {2016}, abstract = {Background: Walking speed decreases in old age. Even though old adults regularly participate in exercise interventions, we do not know how the intervention-induced changes in physical abilities produce faster walking. The Potsdam Gait Study (POGS) will examine the effects of 10 weeks of power training and detraining on leg muscle power and, for the first time, on complete gait biomechanics, including joint kinematics, kinetics, and muscle activation in old adults with moderate mobility disability. Methods/Design: POGS is a randomized controlled trial with two arms, each crossed over, without blinding. Arm 1 starts with a 10-week control period to assess the reliability of the tests and is then crossed over to complete 25-30 training sessions over 10 weeks. Arm 2 completes 25-30 exercise sessions over 10 weeks, followed by a 10-week follow-up (detraining) period. The exercise program is designed to improve lower extremity muscle power. Main outcome measures are: muscle power, gait speed, and gait biomechanics measured at baseline and after 10 weeks of training and 10 weeks of detraining. Discussion: It is expected that power training will increase leg muscle power measured by the weight lifted and by dynamometry, and these increased abilities become expressed in joint powers measured during gait. Such favorably modified powers will underlie the increase in step length, leading ultimately to a faster walking speed. POGS will increase our basic understanding of the biomechanical mechanisms of how power training improves gait speed in old adults with moderate levels of mobility disabilities. (C) 2016 S. Karger AG, Basel}, language = {en} } @article{HeinzelLorenzPelzetal.2016, author = {Heinzel, Stephan and Lorenz, Robert C. and Pelz, Patricia and Heinz, Andreas and Walter, Henrik and Kathmann, Norbert and Rapp, Michael A. and Stelzel, Christine}, title = {Neural correlates of training and transfer effects in working memory in older adults}, series = {NeuroImage : a journal of brain function}, volume = {134}, journal = {NeuroImage : a journal of brain function}, publisher = {Elsevier}, address = {San Diego}, issn = {1053-8119}, doi = {10.1016/j.neuroimage.2016.03.068}, pages = {236 -- 249}, year = {2016}, abstract = {As indicated by previous research, aging is associated with a decline in working memory (WM) functioning, related to alterations in fronto-parietal neural activations. At the same time, previous studies showed that WM training in older adults may improve the performance in the trained task (training effect), and more importantly, also in untrained WM tasks (transfer effects). However, neural correlates of these transfer effects that would improve understanding of its underlying mechanisms, have not been shown in older participants as yet. In this study, we investigated blood-oxygen-level-dependent (BOLD) signal changes during n-back performance and an untrained delayed recognition (Sternberg) task following 12 sessions (45 min each) of adaptive n-back training in older adults. The Sternberg task used in this study allowed to test for neural training effects independent of specific task affordances of the trained task and to separate maintenance from updating processes. Thirty-two healthy older participants (60-75 years) were assigned either to an n-back training or a no-contact control group. Before (t1) and after (t2) training/waiting period, both the n-back task and the Sternberg task were conducted while BOLD signal was measured using functional Magnetic Resonance Imaging (fMRI) in all participants. In addition, neuropsychological tests were performed outside the scanner. WM performance improved with training and behavioral transfer to tests measuring executive functions, processing speed, and fluid intelligence was found. In the training group, BOLD signal in the right lateral middle frontal gyrus/caudal superior frontal sulcus (Brodmann area, BA 6/8) decreased in both the trained n-back and the updating condition of the untrained Sternberg task at t2, compared to the control group. fMRI findings indicate a training-related increase in processing efficiency of WM networks, potentially related to the process of WM updating. Performance gains in untrained tasks suggest that transfer to other cognitive tasks remains possible in aging. (C) 2016 Elsevier Inc. All rights reserved.}, language = {en} } @article{vonderMalsburgKlieglVasishth2015, author = {von der Malsburg, Titus Raban and Kliegl, Reinhold and Vasishth, Shravan}, title = {Determinants of Scanpath Regularity in Reading}, series = {Cognitive science : a multidisciplinary journal of anthropology, artificial intelligence, education, linguistics, neuroscience, philosophy, psychology ; journal of the Cognitive Science Society}, volume = {39}, journal = {Cognitive science : a multidisciplinary journal of anthropology, artificial intelligence, education, linguistics, neuroscience, philosophy, psychology ; journal of the Cognitive Science Society}, number = {7}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {0364-0213}, doi = {10.1111/cogs.12208}, pages = {1675 -- 1703}, year = {2015}, abstract = {Scanpaths have played an important role in classic research on reading behavior. Nevertheless, they have largely been neglected in later research perhaps due to a lack of suitable analytical tools. Recently, von der Malsburg and Vasishth (2011) proposed a new measure for quantifying differences between scanpaths and demonstrated that this measure can recover effects that were missed with the traditional eyetracking measures. However, the sentences used in that study were difficult to process and scanpath effects accordingly strong. The purpose of the present study was to test the validity, sensitivity, and scope of applicability of the scanpath measure, using simple sentences that are typically read from left to right. We derived predictions for the regularity of scanpaths from the literature on oculomotor control, sentence processing, and cognitive aging and tested these predictions using the scanpath measure and a large database of eye movements. All predictions were confirmed: Sentences with short words and syntactically more difficult sentences elicited more irregular scanpaths. Also, older readers produced more irregular scanpaths than younger readers. In addition, we found an effect that was not reported earlier: Syntax had a smaller influence on the eye movements of older readers than on those of young readers. We discuss this interaction of syntactic parsing cost with age in terms of shifts in processing strategies and a decline of executive control as readers age. Overall, our results demonstrate the validity and sensitivity of the scanpath measure and thus establish it as a productive and versatile tool for reading research.}, language = {en} } @article{BeurskensHelmichReinetal.2014, author = {Beurskens, Rainer and Helmich, Ingo and Rein, Robert and Bock, Otmar L.}, title = {Age-related changes in prefrontal activity during walking in dual-task situations: A fNIRS study}, series = {International journal of psychophysiology}, volume = {92}, journal = {International journal of psychophysiology}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0167-8760}, doi = {10.1016/j.ijpsycho.2014.03.005}, pages = {122 -- 128}, year = {2014}, abstract = {Background: Previous studies suggest that the human gait is under control of higher-order cognitive processes, located in the frontal lobes, such that an age-related degradation of cognitive capabilities has a negative impact on gait. Results: Our behavioral data partly confirm previous accounts on higher dual-task costs in stepping parameters (i.e., decreased step duration) in old age, particularly with a visual task and negative dual-task cost (i.e., improved performance) during the verbal task in young adults. Functional imaging data revealed little change of prefrontal activation from single- to dual-task walking in young individuals. In the elderly, however, prefrontal activation substantially decreased during dual-task walking with a complex visual task. Conclusion: We interpret these findings as evidence for a shift of processing resources from the prefrontal cortex to other brain regions when seniors face the challenge of walking and concurrently executing a visually demanding task. (C) 2014 Elsevier B.V. All rights reserved.}, language = {en} } @misc{BeijersbergenGranacherVandervoortetal.2013, author = {Beijersbergen, Chantal M. I. and Granacher, Urs and Vandervoort, A. A. and DeVita, P. and Hortobagyi, Tibor}, title = {The biomechanical mechanism of how strength and power training improves walking speed in old adults remains unknown}, series = {Ageing research reviews : ARR}, volume = {12}, journal = {Ageing research reviews : ARR}, number = {2}, publisher = {Elsevier}, address = {Clare}, issn = {1568-1637}, doi = {10.1016/j.arr.2013.03.001}, pages = {618 -- 627}, year = {2013}, abstract = {Maintaining and increasing walking speed in old age is clinically important because this activity of daily living predicts functional and clinical state. We reviewed evidence for the biomechanical mechanisms of how strength and power training increase gait speed in old adults. A systematic search yielded only four studies that reported changes in selected gait biomechanical variables after an intervention. A secondary analysis of 20 studies revealed an association of r(2) = 0.21 between the 22\% and 12\% increase, respectively, in quadriceps strength and gait velocity in 815 individuals age 72. In 6 studies, there was a correlation of r(2) = 0.16 between the 19\% and 9\% gains in plantarflexion strength and gait speed in 240 old volunteers age 75. In 8 studies, there was zero association between the 35\% and 13\% gains in leg mechanical power and gait speed in 150 old adults age 73. To increase the efficacy of intervention studies designed to improve gait speed and other critical mobility functions in old adults, there is a need for a paradigm shift from conventional (clinical) outcome assessments to more sophisticated biomechanical analyses that examine joint kinematics, kinetics, energetics, muscle-tendon function, and musculoskeletal modeling before and after interventions.}, language = {en} }