Restorative Neurology and Neuroscience - Volume 34, issue 5

Authors: Fernández-del-Olmo, Miguel

Article Type: Letter

DOI: 10.3233/RNN-160648

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 691-692, 2016

Authors: Arcolin, Ilaria | Pisano, Fabrizio | Delconte, Carmen | Godi, Marco | Schieppati, Marco | Mezzani, Alessandro | Picco, Daniele | Grasso, Margherita | Nardone, Antonio

Article Type: Letter

DOI: 10.3233/RNN-169001

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 693-695, 2016

Authors: Maniglia, Marcello | Pavan, Andrea | Sato, Giovanni | Contemori, Giulio | Montemurro, Sonia | Battaglini, Luca | Casco, Clara

Article Type: Research Article

Abstract: Background: Macular Degeneration (MD), a visual disease that produces central vision loss, is one of the main causes of visual disability in western countries. Patients with MD are forced to use a peripheral retinal locus (PRL) as a substitute of the fovea. However, the poor sensitivity of this region renders basic everyday tasks very hard for MD patients. Objective: We investigated whether perceptual learning (PL) with lateral masking in the PRL of MD patients, improved their residual visual functions. Method: Observers were trained with two distinct contrast detection tasks: (i) a Yes/No task with no …feedback (MD: N = 3; controls: N = 3), and (ii) a temporal two-alternative forced choice task with feedback on incorrect trials (i.e., temporal-2AFC; MD: N = 4; controls: N = 3). Observers had to detect a Gabor patch (target) flanked above and below by two high contrast patches (i.e., lateral masking). Stimulus presentation was monocular with durations varying between 133 and 250 ms. Participants underwent 24– 27 training sessions in total. Results: Both PL procedures produced significant improvements in the trained task and learning transferred to visual acuity. Besides, the amount of transfer was greater for the temporal-2AFC task that induced a significant improvement of the contrast sensitivity for untrained spatial frequencies. Most importantly, follow-up tests on MD patients trained with the temporal-2AFC task showed that PL effects were retained between four and six months, suggesting long-term neural plasticity changes in the visual cortex. Conclusion: The results show for the first time that PL with a lateral masking configuration has strong, non-invasive and long lasting rehabilitative potential to improve residual vision in the PRL of patients with central vision loss. Show more

Keywords: Macular degeneration (MD), perceptual learning, neural plasticity, visual rehabilitation

DOI: 10.3233/RNN-150575

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 697-720, 2016

Authors: Franz, Elizabeth A. | Fu, Yan | Moore, Matthew | Winter, Taylor | Mayne, Terence | Debnath, Ranjan | Stringer, Catherine

Article Type: Research Article

Abstract: Background: Mirror therapy (MT) is an increasingly employed method aimed at reducing phantom pain and other negative sensations following loss of a limb or damage to sensorimotor systems. However, the brain processes associated with the perception of limb ownership, a key correlate of MT, are unknown. Objective: To examine whether transient perceptions of limb ownership together with associated neural activity can be elucidated using a purpose-developed mirror reflection task combined with electrophysiological (EEG) measures and cutting-edge analyses. Methods: Brain activity was measured online using EEG in 20 healthy controls while they produced opening-closing movements of …one hand in control conditions or while viewing the mirror reflection of the movements. The key experimental condition required participants to make a foot pedal response whenever a change in perception of ownership (of a mirror-reflected limb) occurred (Mirror condition). Control conditions and a strict epoching regime were employed using standard subtractive logic to isolate the perception of limb ownership (which was further verified by self-reports). Results: Data from 15 participants were suitable for complete analysis; the remaining reported no experience of ownership. Significant spectral power increases were found in central-parietal regions in association with perceptions of ownership, with the most prominent effect specific to the alpha frequency band (8–13 Hz) measured at the right parietal area. Source localization analyses further identified brain networks associated with the mirror reflection condition in the alpha frequency (parietal lobe) and the beta frequency (middle temporal areas). These were distinct from localized networks associated with the foot pedal response. Conclusion: Transient perceptions of ownership can be captured experimentally, and are associated with localized sites of neural activation. This is an initial step toward eventual development of therapeutic targets for interventions including brain computer interfaces (BCIs) aimed at ameliorating the negative effects associated with impaired or missing limbs. Show more

Keywords: Neurorehabilitation, amputation, phantom limb, mirror, perception of ownership, bimanual

DOI: 10.3233/RNN-150622

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 721-732, 2016

Authors: Jones, Paul W. | Borich, Michael R. | Vavsour, Irene | Mackay, Alex | Boyd, Lara A.

Article Type: Research Article

Abstract: Background: Hemiparesis is one of the most prevalent chronic disabilities after stroke. Biochemical and structural magnetic resonance imaging approaches may be employed to study the neural substrates underpinning upper-extremity (UE) recovery after chronic stroke. Objective: The purposes of this study were to 1) quantify anatomical and metabolic differences in the precentral gyrus, and 2) test the relationships between anatomical and metabolic differences, and hemiparetic arm function in individuals in the chronic stage of stroke recovery. Our hypotheses were: 1) the Stroke group would exhibit reduced precentral gyrus cortical thickness and lower concentrations of total N-acetylaspartate (tNAA) and …glutamate+glutamine (Glx) in the ipsilesional motor cortex; and 2) that each of these measures would be associated with UE motor function after stroke. Methods: Seventeen individuals with chronic (>6 months) subcortical ischemic stroke and eleven neurologically healthy controls were recruited. Single voxel proton magnetic resonance spectroscopy (H1 MRS) was performed to measure metabolite concentrations of tNAA and Glx in the precentral gyrus in both ipsilesional and contralesional hemispheres. Surface-based cortical morphometry was used to quantify precentral gyral thickness. Upper-extremity motor function was assessed using the Wolf Motor Function Test (WMFT). Results: Results demonstrated significantly lower ipsilesional tNAA and Glx concentrations and precentral gyrus thickness in the Stroke group. Ipsilesional tNAA and Glx concentration and precentral gyrus thickness was significantly lower in the ipsilesional hemisphere in the Stroke group. Parametric correlation analyses revealed a significant positive relationship between precentral gyrus thickness and tNAA concentration bilaterally. Multivariate regression analyses revealed that ipsilesional concentrations of tNAA and Glx predicted the largest amount of variance in WMFT scores. Cortical thickness measures alone did not predict a significant amount of variance in WMFT scores. Conclusion: While stroke impairs both structure and biochemistry in the ipsilesional hemisphere our data suggest that tNAA has the strongest relationship with motor function. Show more

Keywords: Stroke, human, metabolite, motor function, cortical thickness

DOI: 10.3233/RNN-150623

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 733-746, 2016

Authors: Chang, Won Hyuk | Uhm, Kyeong Eun | Shin, Yong-Il | Pascual-Leone, Alvaro | Kim, Yun-Hee

Article Type: Research Article

Abstract: Background and Purpose: High-frequency repetitive transcranial magnetic stimulation (rTMS) aids motor recovery in patients with subacute stroke. However, the response to high-frequency rTMS is highly variable between patients. The aim of this study was to identify the factors associated with improved motor function in response to high-frequency rTMS in subacute stroke patients with moderate to severe upper extremity motor involvement. Methods: Sixty-two patients with subacute stroke were enrolled. rTMS was applied over the primary motor cortex of the affected hemisphere at 10 Hz with 1,000 pulses/day for 10 days. Upper limb motor function was scored with the upper …limb of Fugl-Meyer Assessment (FMA-UL) score before intervention and immediately after intervention. All FMA-UL changes greater than or equal to 5 points were considered clinically significant. Potential influencing factors considered included patient characteristics, motor function, corticospinal tract (CST) integrity assessments, and genetics. Multivariate logistic regression analysis was used to identify the significance of each of these factors. Results: We found that the two factors with the greatest impact on the improvement in FMA-UL score were: 1) the functional integrity of the CST, and 2) the brain-derived neurotrophic factor (BDNF) genotype (p  < 0.05). Age tended to influence clinically significant changes in the FMA-UL score, although this effect was not significant. Conclusion: Our findings suggest that high-frequency rTMS interventions aimed at improving upper extremity motor function in patients with subacute stroke with moderate to severe motor involvement should be individually tailored according to functional CST status and BDNF genotype. Show more

Keywords: Transcranial magnetic stimulation, rTMS, motor recovery, BDNF, cortical excitability, stroke

DOI: 10.3233/RNN-150634

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 747-755, 2016

Authors: Jafari, Zahra | Malayeri, Saeed

Article Type: Research Article

Abstract: Background: Congenital visual deprivation underlies neural plasticity in different brain areas, and provides an outstanding opportunity to study the neuroplastic capabilities of the brain. Objectives: The present study aimed to investigate the effect of congenital blindness on subcortical auditory processing using electrophysiological and behavioral assessments in children. Methods: A total of 47 children aged 8–12 years, including 22 congenitally blind (CB) children and 25 normal-sighted (NS) control, were studied. All children were tested using an auditory brainstem response (ABR) test with both click and speech stimuli. Speech recognition and musical abilities were tested using standard …tools. Results: Significant differences were observed between the two groups in speech ABR wave latencies A, F and O (p ≤0.043), wave amplitude F (p  = 0.039), V–A slope (p  = 0.026), and three spectral magnitudes F0, F1 and HF (p ≤0.002). CB children showed a superior performance compared to NS peers in all the subtests and the total score of musical abilities (p ≤0.003). Moreover, they had significantly higher scores during the nonsense syllable test in noise than the NS children (p  = 0.034). Significant negative correlations were found only in CB children between the total music score and both wave A (p  = 0.039) and wave F (p  = 0.029) latencies, as well as nonsense-syllable test in noise and the wave A latency (p  = 0.041). Conclusion: Our results suggest that neuroplasticity resulting from congenital blindness can be measured subcortically and has a heightened effect on temporal, musical and speech processing abilities. The findings have been discussed based on models of plasticity and the influence of corticofugal modulation in synthesizing complex auditory stimuli. Show more

Keywords: Congenitally-blind, auditory brainstem response, speech, corticofugal modulation

DOI: 10.3233/RNN-160639

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 757-768, 2016

Authors: Kristjánsson, Árni | Moldoveanu, Alin | Jóhannesson, Ómar I. | Balan, Oana | Spagnol, Simone | Valgeirsdóttir, Vigdís Vala | Unnthorsson, Rúnar

Article Type: Research Article

Abstract: An exciting possibility for compensating for loss of sensory function is to augment deficient senses by conveying missing information through an intact sense. Here we present an overview of techniques that have been developed for sensory substitution (SS) for the blind, through both touch and audition, with special emphasis on the importance of training for the use of such devices, while highlighting potential pitfalls in their design. One example of a pitfall is how conveying extra information about the environment risks sensory overload. Related to this, the limits of attentional capacity make it important to focus on key information and …avoid redundancies. Also, differences in processing characteristics and bandwidth between sensory systems severely constrain the information that can be conveyed. Furthermore, perception is a continuous process and does not involve a snapshot of the environment. Design of sensory substitution devices therefore requires assessment of the nature of spatiotemporal continuity for the different senses. Basic psychophysical and neuroscientific research into representations of the environment and the most effective ways of conveying information should lead to better design of sensory substitution systems. Sensory substitution devices should emphasize usability, and should not interfere with other inter- or intramodal perceptual function. Devices should be task-focused since in many cases it may be impractical to convey too many aspects of the environment. Evidence for multisensory integration in the representation of the environment suggests that researchers should not limit themselves to a single modality in their design. Finally, we recommend active training on devices, especially since it allows for externalization, where proximal sensory stimulation is attributed to a distinct exterior object. Show more

Keywords: Sensory substitution, neural plasticity, multisensory perception

DOI: 10.3233/RNN-160647

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 769-787, 2016

Authors: Kawakami, Michiyuki | Fujiwara, Toshiyuki | Ushiba, Junichi | Nishimoto, Atsuko | Abe, Kaoru | Honaga, Kaoru | Nishimura, Atsuko | Mizuno, Katsuhiro | Kodama, Mitsuhiko | Masakado, Yoshihisa | Liu, Meigen

Article Type: Research Article

Abstract: Background: Hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy improved paretic upper extremity motor function in patients with severe to moderate hemiparesis. We hypothesized that brain machine interface (BMI) training would be able to increase paretic finger muscle activity enough to apply HANDS therapy in patients with severe hemiparesis, whose finger extensor was absent. Objective : The aim of this study was to assess the efficacy of BMI training followed by HANDS therapy in patients with severe hemiparesis. Methods : Twenty-nine patients with chronic stroke who could not extend their paretic fingers were participated this study. We applied …BMI training for 10 days at 40 min per day. The BMI detected the patients’ motor imagery of paretic finger extension with event-related desynchronization (ERD) over the affected primary sensorimotor cortex, recorded with electroencephalography. Patients wore a motor-driven orthosis, which extended their paretic fingers and was triggered with ERD. When muscle activity in their paretic fingers was detected with surface electrodes after 10 days of BMI training, we applied HANDS therapy for the following 3 weeks. In HANDS therapy, participants received closed-loop, electromyogram-controlled, neuromuscular electrical stimulation (NMES) combined with a wrist-hand splint for 3 weeks at 8 hours a day. Before BMI training, after BMI training, after HANDS therapy and 3month after HANDS therapy, we assessed Fugl-Meyer Assessment upper extremity motor score (FMA) and the Motor Activity Log14-Amount of Use (MAL-AOU) score. Results : After 10 days of BMI training, finger extensor activity had appeared in 21 patients. Eighteen of 21 patients then participated in 3 weeks of HANDS therapy. We found a statistically significant improvement in the FMA and the MAL-AOU scores after the BMI training, and further improvement was seen after the HANDS therapy. Conclusion : Combining BMI training with HANDS therapy could be an effective therapeutic strategy for severe UE paralysis after stroke. Show more

Keywords: Brain-machine interface, rehabilitation, upper extremity, stroke

DOI: 10.3233/RNN-160652

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 789-797, 2016

Authors: Schambra, Heidi M. | Martinez-Hernandez, Isis E. | Slane, Kevin J. | Boehme, Amelia K. | Marshall, Randolph S. | Lazar, Ronald M.

Article Type: Research Article

Abstract: Background: Reducing inhibitory neurotransmission with pharmacological agents is a potential approach for augmenting plasticity after stroke. Previous work in healthy subjects showed diminished intracortical inhibition after administration of theophylline. Objective: We assessed the effect of single-dose theophylline on intracortical and interhemispheric inhibition in patients with chronic stroke, in a double-blind, placebo-controlled, cross-over study. Methods: Eighteen subjects were randomly administered 300 mg of extended-release theophylline or placebo. Immediately and 5 hours following administration, transcranial magnetic stimulation was used to assess bihemispheric resting motor threshold, short-interval intracortical inhibition, long-interval intracortical inhibition, and interhemispheric inhibition. Adverse effects on cardiovascular, …neurological, and motor performance outcomes were also surveilled. Change between morning and afternoon sessions were compared across conditions. One week later, patients underwent the same assessments after crossing over to the opposite experimental condition. Subjects and investigators were blinded to the experimental condition during data acquisition and analysis. Results: For both hemispheres, changes in intracortical or interhemispheric neurophysiology were comparable under theophylline and placebo conditions. Theophylline induced no adverse neurological, cardiovascular, or motor performance effects. For both conditions and hemipsheres, the baseline level of inhibition inversely correlated with its change between sessions: less baseline inhibition (i.e. disinhibition) was associated with a strengthening in inhibition over the day, and vice versa. Conclusion: A single dose of theophylline is well-tolerated by patients with chronic stroke, but does not alter cortical excitability. The inverse relationship between baseline inhibition and its change suggests the existence of a homeostatic process. The lack of effect on cortical inhibition may be related to an insufficiently long exposure to theophylline, or to differential responsiveness of disinhibited neural circuitry in patients with stroke. Show more

Keywords: Recovery of function, transcranial magnetic stimulation, cerebral infarction, motor cortex, homeostasis

DOI: 10.3233/RNN-160657

Citation: Restorative Neurology and Neuroscience, vol. 34, no. 5, pp. 799-813, 2016