Restorative Neurology and Neuroscience - Volume 29, issue 2

Authors: Sturm, Walter | Schnitker, Ralph | Grande, Marion | Huber, Walter | Willmes, Klaus

Article Type: Research Article

Abstract: Purpose: In an fMRI study the functional networks involved in auditory selective attention for sounds and words were investigated. Methods: 24 healthy volunteers (12 male, 12 female) had to respond to a category of targets (animal sounds vs. musical instruments, spoken names of instruments vs. animals; 6 targets, 12 nontargets) presented via headphones. Results: Under both the sound and word condition besides left superior and middle temporal lobe activation there was bilateral activity in the superior frontal (including the anterior cingulate cortex ACC), middle and inferior frontal and inferior parietal lobes. Under both conditions we also found cerebellar activity. In …general there was a high overlap of the related attention networks for both conditions. Conclusions: The activation patterns revealed a high overlap across stimulus conditions with only slight modulation caused by the quality of the auditory material. For rehabilitation of attention deficits after brain damage this implicates that a single training procedure might address a common network for selective attention deficits under different stimulus conditions. Show more

Keywords: Selective attention, auditory stimulation, sounds, words, fMRI, attention therapy

DOI: 10.3233/RNN-2011-0569

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 73-83, 2011

Authors: Buttkus, Franziska | Baur, Volker | Jabusch, Hans-Christian | de la Cruz Gomez-Pellin, Maria | Paulus, Walter | Nitsche, Michael A. | Altenmüller, Eckart

Article Type: Research Article

Abstract: Background: Focal dystonia in musicians (MD) is a task-specific movement disorder with a loss of voluntary motor control during instrumental playing. Defective inhibition on different levels of the central nervous system is involved in the pathophysiology. Sensorimotor retraining is a therapeutic approach to MD and aims to establish non-dystonic movements. Transcranial direct current stimulation (tDCS) modulates cortical excitability and alters motor performance. In this study, tDCS of the motor cortex was expected to assist retraining at the instrument. Methods: Nine professional pianists suffering from MD were included in a placebo-controlled double-blinded study. Retraining consisted of slow, voluntarily controlled movements on …the piano and was combined with tDCS. Patients were treated with three stimulation protocols: anodal tDCS, cathodal tDCS and placebo stimulation. Results: No beneficial effects of single-session tDCS-supported sensorimotor retraining on fine motor control in pianists with MD were found in all three conditions. Conclusions: The main cause of the negative result of this study may be the short intervention time. One retraining session with a duration of 20 min seems not sufficient to improve symptoms of MD. Additionally, a single tDCS session might not be sufficient to modify sensorimotor learning of a highly skilled task in musicians with dystonia. Show more

Keywords: Focal dystonia, motor control, neuronal plasticity, transcranial direct current stimulation, retraining

DOI: 10.3233/RNN-2011-0582

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 85-90, 2011

Authors: Dai, Haining | MacArthur, Linda | McAtee, Marietta | Hockenbury, Nicole | Das, Paramita | Bregman, Barbara S.

Article Type: Research Article

Abstract: Purpose: The effect of activity based therapies on restoring forelimb function in rats was evaluated when initiated one month after a cervical spinal cord injury. Methods: Adult rats received a unilateral over-hemisection of the spinal cord at C4/5, which interrupts the right side of the spinal cord and the dorsal columns bilaterally, resulting in severe impairments in forelimb function with greater impairment on the right side. One month after injury rats were housed in enriched housing and received daily training in reaching, gridwalk, and CatWalk. A subset of rats received rolipram for 10 days to promote axonal plasticity. Rats were …tested weekly for six weeks for reaching, elevated gridwalk, CatWalk, and forelimb use during vertical exploration. Results: Rats exposed to enriched housing and daily training significantly increased the number of left reaches and pellets grasped and eaten, reduced the number of right forelimb errors on the gridwalk, increased right forelimb use during vertical exploration, recovered more normal step cycles, and reduced their hindlimb base of support on the CatWalk compared to rats in standard cages without daily training. Conclusions: Delayed rehabilitation with enriched housing and daily forelimb training significantly improved skilled, sensorimotor, and automatic forelimb function together after cervical spinal cord injury. Show more

Keywords: Spinal cord injury, forelimb function, functional recovery, rehabilitation

DOI: 10.3233/RNN-2011-0583

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 91-103, 2011

Authors: Borich, Michael | Furlong, Mary | Holsman, Dennis | Kimberley, Teresa Jacobson

Article Type: Research Article

Abstract: Purpose: The time course and neural substrates of motor skill learning are not well-understood in healthy or neurologic patient populations. Certain motor skills undergo off-line skill enhancement following training and the primary motor cortex (M1) may be involved. It is unknown if goal-directed visuomotor skill undergoes off-line enhancement or if M1 is associated with that enhancement. Methods: 32 right-handed, healthy subjects were randomly assigned to two groups: real repetitive transcranial magnetic stimulation (rTMS) or sham rTMS applied to the contralateral M1 immediately following one 20-minute finger tracking training session. Tracking performance and cortical excitability were assessed before and after training, …following rTMS and 24 hours post-training. Results: Results demonstrate that skill performance continues to develop for at least 30 minutes after training completion, is maintained for 24 hours post-training, and is not affected by inhibitory rTMS applied to M1. Level of skill improvement was associated with the degree of intracortical inhibition increase. Conclusions: These results suggest dispersed information processing for goal-directed visuomotor skill learning following training and a relationship between cortical excitability and skill development in healthy individuals. These findings invite further investigation of the neural mechanisms underlying motor skill learning and may have rehabilitation implications for patients with neurologic injury. Show more

Keywords: Motor skill, learning, memory, rTMS, enhancement, primary motor cortex

DOI: 10.3233/RNN-2011-0584

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 105-113, 2011

Authors: Castro, Elena Redondo | Udina, Esther | Verdú, Enrique | Navarro, Xavier

Article Type: Research Article

Abstract: Purpose: The main objectives of this work were to evaluate the development of neuropathic pain after spinal cord injuries of different severities, and to assess changes in central excitability and plasticity by means of wind-up responses and withdrawal reflexes. Methods: Two groups of rats were subjected to spinal cord contusion with forces of 100 or 200 kdyn applied at T8. Measurements of thermal and mechanical pain thresholds as well as wind-up measurements were performed weekly during two months after injury. Withdrawal reflexes were also assessed electrophysiologically. Results: We found that animals with contusion of different severities showed a similar reduction …in nociceptive thresholds. All contused animals showed increased wind-up responses compared to intact animals during the first 2 to 6 weeks post injury. The mean increase of wind-up was higher in rats with stronger spinal cord contusion. Results from the withdrawal reflexes did not correlate with nociceptive behaviors nor wind-up responses, highlighting the plasticity of spinal circuits modulation after SCI. Conclusion: These results indicate that the graded-force spinal cord contusion model is suitable for studying central neuropathic pain, and for assessing changes in wind-up responses. Wind-up measurements can be used as a non-invasive technique to detect changes in central excitability after SCI of different severities. Show more

Keywords: Spinal cord contusion, wind-up, below-level neuropathic pain, plasticity

DOI: 10.3233/RNN-2011-0585

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 115-126, 2011

Authors: Chiwitt, Carolin | Prokosch, Verena | Seeger, Johannes | Thanos, Solon

Article Type: Research Article

Abstract: Purpose: Adult retinal ganglion cells (RGCs) can regenerate their cut axons within peripheral nerve grafts used to replace the distal optic nerve stump. We examined the long-term stabilization of RGCs by guiding their regenerating axons into different termination areas. Methods: The optic nerve (ON) of adult rats was completely cut intraorbitally and its ocular stump was connected with different visual target areas (cortex, midbrain) or with non-visual areas (e.g. muscle). Control groups consisted of blind ending graft and ON cut without graft. The function of the retina was regularly examined by electroretinography. At one, six and nine months postsurgery RGCs …were retrogradely labelled with 4-(4-(didecylamino)styryl)-N-methylpyridinium iodide and examined morphometrically. Regenerating RGCs were categorized into three major classes representing the morphological types I, II and III. Results: Our data show that regenerating RGCs remain stable up to nine months after grafting at the ON, although the numbers of axons are low, that is less than 1%, and this number is not significantly effected by reconnection with targets. However, there are significant quantitatively and morphometrically assessable differences between the experimental groups depending on the tissue the RGCs are connected with visual targets. Regenerating RGCs show the highest stability in morphology if reconnected with visual target tissue. Conclusions: Adult RGCs of the rat can be reconnected with visual centers using a peripheral nerve graft. This reconnection stabilizes the cells at morphological and the retina at functional levels for a long period of time, although it does not significantly increase cell survival. Show more

Keywords: Retina, optic nerve injury, grafting, regeneration, fluorescent dyes

DOI: 10.3233/RNN-2011-0586

Citation: Restorative Neurology and Neuroscience, vol. 29, no. 2, pp. 127-139, 2011