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Schaefer R.S.,Radboud University Nijmegen | Schaefer R.S.,Sint Maartenskliniek Research Development and Education | Vlek R.J.,Radboud University Nijmegen | Desain P.,Radboud University Nijmegen
International Journal of Psychophysiology

Previous work has shown that mental imagination of sound generally elicits an increase of alpha band activity (8-12. Hz) in the electroencephalogram (EEG). In addition, alpha activity has been shown to be related to aspects of music processing. In the current study, EEG signatures were investigated for perception and imagery of two different natural musical phrases. The responses are compared between tasks and between stimuli. For all tasks and stimuli, posterior alpha band activity was seen, but differences are shown in the power of this response. As expected, imagery resulted in a significantly stronger alpha activation than perception. The comparison of the averaged responses to the stimuli also showed a difference in alpha power, although this effect is seen in different directions. These results are interpreted to indicate that both the tasks and the stimuli modulate an attentional network, which may relate to the inhibition of non-task relevant cortical areas, as well as engagement with the music. © 2011 Elsevier B.V. Source

Berkelmans R.,Helftheuvelweg 11 | Berkelmans R.,BerkelBike BV | Duysens J.,Catholic University of Leuven | Van Kuppevelt D.,Sint Maartenskliniek Research Development and Education
Assistive Technology Research Series

Purpose: To develop a tricycle with Functional Electrical Stimulation (FES) for the leg muscles of spinal cord injured. It has to give the therapeutical benefits of FES, but also be practical in speed, range and reliability. Methods: We combined voluntary arm cranking with FES leg cycling. Three different models are made. One model is just a front part with one wheel, which can be attached and detached to a wheelchair. Two models can also be used outdoor tricycles and all models can be used as a stationary bike. Results: Compared with FES leg cycling only, the power output and the stamina improved. The combined exercise from arms and legs gives a higher oxygen uptake then separate exercises. Conclusion: A practical outdoor tricycle for people with SCI is developed. The different models are suitable for complete spinal cord injured ranging from C5 to T12. © 2010 The authors and IOS Press. All rights reserved. Source

Ruiter M.B.,Sint Maartenskliniek Research Development and Education | Kolk H.H.J.,Radboud University Nijmegen | Rietveld T.C.M.,Radboud University Nijmegen | Dijkstra N.,Radboud University Nijmegen | Lotgering E.,Radboud University Nijmegen

Background: A well-known test for measuring verbal adequacy (i.e., verbal effectiveness) in mildly impaired aphasic speakers is the Amsterdam-Nijmegen Everyday Language Test (ANELT; Blomert, Koster, & Kean, 1995). Aphasia therapy practitioners score verbal adequacy qualitatively when they administer the ANELT to their aphasic clients in clinical practice. Aims: The current study investigated whether the construct validity of the ANELT could be further improved by substituting the qualitative score by a quantitative one, which takes the number of essential information units into account. The new quantitative measure could have the following advantages: the ability to derive a quantitative score of verbal efficiency, as well as improved sensitivity to detect changes in functional communication over time. Methods & Procedures: The current study systematically compared a new quantitative measure of verbal effectiveness with the current ANELT Comprehensibility scale, which is based on qualitative judgements. A total of 30 speakers of Dutch participated: 20 non-aphasic speakers and 10 aphasic patients with predominantly expressive disturbances. Outcomes & Results: Although our findings need to be replicated in a larger group of aphasic speakers, the main results suggest that the new quantitative measure of verbal effectiveness is more sensitive to detect change in verbal effectiveness over time. What is more, it can be used to derive a measure of verbal efficiency. Conclusions: The fact that both verbal effectiveness and verbal efficiency can be reliably as well as validly measured in the ANELT is of relevance to clinicians. It allows them to obtain a more complete picture of aphasic speakers' functional communication skills. ©2011 Psychology Press. Source

Luites J.W.H.,Sint Maartenskliniek Research Development and Education | Wymenga A.B.,Sint Maartenskliniek | Blankevoort L.,University of Amsterdam | Kooloos J.M.G.,Radboud University Nijmegen | And 2 more authors.
Medical Engineering and Physics

Anterior cruciate ligament reconstruction techniques are evolving with innovations like double-bundle (DB) grafts and computer assistance. The current DB techniques do not appear to make the clinical difference yet. Insight in various techniques may lead to better results. In this study, the anterior laxity of a DB reconstruction with an anteromedial (AM) graft fixated in 90° of flexion and a posterolateral (PL) graft fixated in 20° and computer-assisted anatomically placed femoral attachments was compared to normal values and single-bundle grafts. In 8 fresh-frozen human cadaveric knees, the anterior laxity was tested from 0° to 90° flexion, with a 100. Newton (N) anterior tibial load in joints with (1) intact ACL, (2) torn ACL, (3) single-bundle (SB) graft tensed with 15. N in 20°, (4) anatomic AM graft tensed with 15. N in 90°, (5) anatomic PL graft tensed with 15. N in 20°, and (6) anatomic DB graft (4. +. 5).All reconstructions caused a posterior position of the tibia. Relative to the normal anterior laxity, the single-bundle techniques showed significantly increased laxities: The SB technique in 0° (+1.1. mm) and 15° (+1.7. mm); The AM reconstructions in 45° (+1.6. mm) and 90° (+1.5. mm); The PL reconstructions in all angles (from +1.4 to +2.3. mm), except in 0°. The anatomic DB technique showed no significantly increased laxities and restored normal laxity in all angles. © 2011 IPEM. Source

Nonnekes J.,Radboud University Nijmegen | De Niet M.,Radboud University Nijmegen | Nijhuis L.B.O.,Donders Institute for Brain | De Bot S.T.,Donders Institute for Brain | And 6 more authors.
Journal of Neurology

Hereditary spastic paraplegia (HSP) is characterized by progressive lower extremity spasticity and weakness, due to retrograde axonal degeneration of the corticospinal tract and posterior spinal columns. HSP patients fall frequently. We hypothesized that delayed postural responses contribute to their balance impairments. To distinguish between a delay in afferent and efferent signals, we combined postural responses with a startling acoustic stimulus (SAS). The SAS triggers a postural response directly, bypassing afferent proprioceptive input. We performed two experiments. First, 18 HSP patients and nine healthy controls stood on a balance platform and were instructed to counteract forward and backward balance perturbations, without taking a step or grabbing a handrail. Second, 12 HSP patients and nine controls received backward perturbations, while a SAS accompanied onset of platform motion in 25 % of trials. HSP patients were less successful than controls in maintaining balance following backward and forward perturbations. Furthermore, latencies of postural responses were significantly delayed in HSP-patients, by 34 ms in gastrocnemius following forward, and by 38 ms in tibialis anterior following backward perturbations. A SAS accelerated postural responses in all participants, but more so in HSP patients whose latencies were normalized. Our results suggest that delayed postural responses in HSP patients contribute to their balance problems. Combining balance perturbations with a SAS restored normal latencies, suggesting that conduction of efferent signals (presumably by the reticulospinal tract) is normal. We therefore suggest that the delayed postural responses in HSP are caused by slowed conduction time via the posterior spinal columns. © 2013 Springer-Verlag Berlin Heidelberg. Source

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