- Email: [email protected]
Clinical overview of upper limb dysfunction in hemiparetic stroke
e44
Abstracts / Neuroscience Research 68S (2010) e4–e52
S3-6-2-3 Task-dependent V1 responses in adult human retinal degeneration patients Yoichiro Masuda Dept Ophthalmol, Jikei Univ Sch of Med, Tokyo After the critical period, plasticity in visual cortex is reduced and stability becomes dominant. In people with healthy visual systems, large-scale features of neural circuits – such as the white matter projection zones do not change significantly after the critical period. However, there is still uncertainty about neural circuit reorganization in disease conditions. An important question is whether primary visual cortex (V1) reorganizes due to re-activated plasticity if the retina is damaged after the critical period. Some fMRI studies reported large-scale reorganization in human macular degeneration (MD) patients whereas others did not. We investigated regions of human V1 deprived of input by a retinal lesion (lesion projection zone, or LPZ) in subjects with MD and retinitis pigmentosa. BOLD responses in the V1 LPZ can be elicited by task demands even in regions deprived of feed-forward input. In experiments analyzing these responses, we find that the population receptive field (pRF) sizes of these task-dependent LPZ responses are unusually large compared with the pRF sizes in healthy V1. Our hypothesis is that task-dependent BOLD responses in the LPZ of subjects with retinal dysfunction arise because (a) in the healthy brain there are signals from the LGN to V1 that gate the entry of extrastriate signals, and (b) these gating signals are eliminated by the retinal disease. This model explains response differences between controls and subjects with retinal dysfunction by the loss of the feed-forward gating signal caused by the disease; the model does not appeal to a large-scale cortical reorganization. We speculate on the implications of this hypothesis for visual therapy designed to replace the missing V1 LPZ inputs and restore vision.
modify biological destiny of severely impaired motor function after extensive brain lesion.In terms of rehabilitative intervention, one of the major determinants of rehabilitation outcome is augmented dose of practice and thereby dose of opportunity for motor drive from the motor related areas either by constraint-induced movement therapy, man-to-man taskoriented therapy or robot-assisted therapy. To enhance gains of practice after the same dose of intervention, principles of motor learning such as knowledge of results and rewards are clinically essential. Additionally neuromodulations via neuro-pharmacological intervention, brain-stimulation, and brain–machine interface are promising strategies. However unbiased monitoring of long-term effect, real-world outcome, and possibility for maladaptation is required. References Miyai et al., 2000. Neurorehab Neural Repair 14, 141–147. Yagura et al., 2003. Arch Phys Med Rehab 84, 1687–91. Hatakenaka et al. 2007. NeuroImage 34, 33–39. Hatakenaka et al., 2007. Neurology 69, 348–355. doi:10.1016/j.neures.2010.07.440
S3-7-1-2 A functional threshold for long-term use of hand and arm function can be determined: Predictions from a computational model and supporting data from the extremity constraint-induced therapy evaluation (EXCITE) trial Nicolas Schweighofer 1 , Cheol E. Han 2 , Steven L. Wolf 3 , Michael A. Arbib 2,3 , Carolee J. Winstein 1,3 1
doi:10.1016/j.neures.2010.07.438
S3-6-2-4 Sequence learning by neuronal ensemble in primary visual cortex Yang Dan Dept Molecular and Cell Biology, UC Berkeley, CA Experience-dependent plasticity in adult visual cortex plays importantroles in visual processing and perceptual learning. Repeated visualstimulation can modify cortical responses on a variety of time scales, andthese modifications have been well characterized at the level of singleneuron receptive field (RF) properties. However, visual perception dependson the ensemble activity of large neuronal networks with emergent dynamicsnot well predicted by individual RF properties. How spatiotemporalpatterns of ensemble activity are modified by visual experience remainspoorly understood. In this study, we found that repeated stimulation witha moving object enhances sequential firing of cortical neurons thatrepresents the stimulus trajectory. Multielectrode recording in the visualcortex of both anesthetized and awake head-fixed rats showed that a movingstimulus evoked sequential firing of the neurons whose RFs fall along themotion path. After repeated motion stimulation (conditioning), a teststimulus consisting of a single flash at the starting point of the motionpath evoked more sequential spiking of the neurons similar to that evokedby the motion stimulus. This recall effect was found only for teststimulus at the starting point of the motion path, and it persisted for ∼5 min after 100 repeats of motion conditioning. Interestingly, expression ofthis plasticity in awake animals depended on the brain state:conditioning-induced increase in sequential firing was observed during asynchronized (rowsy) state with large-amplitude, low-frequency corticalactivity, but not in the desynchronized (lert) state with high-frequency activity. Such brain state-dependent enhancement ofsequential neuronal spiking may contribute to short-term memory of visualstimulus sequence and perceptual inference based on recent experience. doi:10.1016/j.neures.2010.07.439
S3-7-1-1 Clinical overview of upper limb dysfunction in hemiparetic stroke Ichiro Miyai Neurorehabilitation Research Institute, Morinomiya Hospital Basic and clinical studies have suggested that functional recovery of hemiparetic upper limb depends on use-dependent plasticity of the damaged brain after stroke. Although patterns of functional reorganization and their longitudinal changes are influenced by size and location of lesion, integrity of the ipsilesional descending motor pathway appears to be essential to restore dexterity of the paretic hand. It is still challenging to favorably
Biokinesiology, USC 2 Computer Science, University of Southern California, Los Angeles, CA 90089 3 Departments of Rehabilitation Medicine, Medicine and Cell Biology, Emory University School of Medicine, VA Rehabilitation R&D Center, Atlanta, GA 30322 Although spontaneous use of the more-affected arm and hand after stroke is an important determinant of participation and quality of life, a number of patients exhibit decreases in use following rehabilitative therapy. A previous neurocomputational model predicted that if the dose of therapy is sufficient to bring performance above a certain threshold, training can be stopped. The aim of this study was to test the hypothesis that there exists a threshold for function of the paretic arm and hand after therapy. If function is above this threshold, spontaneous use will increase in the months following therapy. In contrast, if function is below this threshold, spontaneous use will decrease. New computer simulations are presented showing that changes in arm use following therapy depend on a performance threshold. This prediction was tested by reanalyzing the data from the extremity constraint-induced therapy evaluation (EXCITE) trial, phase III randomized controlled trial in which participants received constraint-induced movement therapy for 2 weeks and were tested both 1 week and 1 year after therapy. The results demonstrate that arm and hand function measured immediately after therapy predicts, on average, the long-term change of arm use. Above a functional threshold, use improves. Below this threshold, use decreases. This reanalysis of the EXCITE trial data provides a group threshold above which a majority of patients, but not all, see spontaneous improvement in use following therapy. A goal of our current research is to provide the means to assess when patients reach their individual threshold. We present preliminary data on models that are fitted to individual patient data and allow us to estimate such individual thresholds as well as the effect of therapy on the interactions between performance and use. doi:10.1016/j.neures.2010.07.441
S3-7-1-3 Effect of hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy for functional recovery after stroke Toshiyuki Fujiwara Department of Rehabilitation Medicine, Keio University School of Medicine We devised a therapeutic approach to facilitate the use of the paretic UE in daily life by combining integrated volitional control electrical stimulation (IVES) with a wrist splint, the hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy. IVES can automatically change its stimulation intensity in direct proportion to the changes in voluntary generated EMG amplitude recorded with surface electrodes placed on the target muscle. The stimulation was applied to the paretic finger extensors. Using this assistive stimulation combined with a splint, patients with moderate to severe hemiparesis, who cannot extend their paretic fingers voluntarily, could extend
Abstracts / Neuroscience Research 68S (2010) e4–e52
S3-6-2-3 Task-dependent V1 responses in adult human retinal degeneration patients Yoichiro Masuda Dept Ophthalmol, Jikei Univ Sch of Med, Tokyo After the critical period, plasticity in visual cortex is reduced and stability becomes dominant. In people with healthy visual systems, large-scale features of neural circuits – such as the white matter projection zones do not change significantly after the critical period. However, there is still uncertainty about neural circuit reorganization in disease conditions. An important question is whether primary visual cortex (V1) reorganizes due to re-activated plasticity if the retina is damaged after the critical period. Some fMRI studies reported large-scale reorganization in human macular degeneration (MD) patients whereas others did not. We investigated regions of human V1 deprived of input by a retinal lesion (lesion projection zone, or LPZ) in subjects with MD and retinitis pigmentosa. BOLD responses in the V1 LPZ can be elicited by task demands even in regions deprived of feed-forward input. In experiments analyzing these responses, we find that the population receptive field (pRF) sizes of these task-dependent LPZ responses are unusually large compared with the pRF sizes in healthy V1. Our hypothesis is that task-dependent BOLD responses in the LPZ of subjects with retinal dysfunction arise because (a) in the healthy brain there are signals from the LGN to V1 that gate the entry of extrastriate signals, and (b) these gating signals are eliminated by the retinal disease. This model explains response differences between controls and subjects with retinal dysfunction by the loss of the feed-forward gating signal caused by the disease; the model does not appeal to a large-scale cortical reorganization. We speculate on the implications of this hypothesis for visual therapy designed to replace the missing V1 LPZ inputs and restore vision.
modify biological destiny of severely impaired motor function after extensive brain lesion.In terms of rehabilitative intervention, one of the major determinants of rehabilitation outcome is augmented dose of practice and thereby dose of opportunity for motor drive from the motor related areas either by constraint-induced movement therapy, man-to-man taskoriented therapy or robot-assisted therapy. To enhance gains of practice after the same dose of intervention, principles of motor learning such as knowledge of results and rewards are clinically essential. Additionally neuromodulations via neuro-pharmacological intervention, brain-stimulation, and brain–machine interface are promising strategies. However unbiased monitoring of long-term effect, real-world outcome, and possibility for maladaptation is required. References Miyai et al., 2000. Neurorehab Neural Repair 14, 141–147. Yagura et al., 2003. Arch Phys Med Rehab 84, 1687–91. Hatakenaka et al. 2007. NeuroImage 34, 33–39. Hatakenaka et al., 2007. Neurology 69, 348–355. doi:10.1016/j.neures.2010.07.440
S3-7-1-2 A functional threshold for long-term use of hand and arm function can be determined: Predictions from a computational model and supporting data from the extremity constraint-induced therapy evaluation (EXCITE) trial Nicolas Schweighofer 1 , Cheol E. Han 2 , Steven L. Wolf 3 , Michael A. Arbib 2,3 , Carolee J. Winstein 1,3 1
doi:10.1016/j.neures.2010.07.438
S3-6-2-4 Sequence learning by neuronal ensemble in primary visual cortex Yang Dan Dept Molecular and Cell Biology, UC Berkeley, CA Experience-dependent plasticity in adult visual cortex plays importantroles in visual processing and perceptual learning. Repeated visualstimulation can modify cortical responses on a variety of time scales, andthese modifications have been well characterized at the level of singleneuron receptive field (RF) properties. However, visual perception dependson the ensemble activity of large neuronal networks with emergent dynamicsnot well predicted by individual RF properties. How spatiotemporalpatterns of ensemble activity are modified by visual experience remainspoorly understood. In this study, we found that repeated stimulation witha moving object enhances sequential firing of cortical neurons thatrepresents the stimulus trajectory. Multielectrode recording in the visualcortex of both anesthetized and awake head-fixed rats showed that a movingstimulus evoked sequential firing of the neurons whose RFs fall along themotion path. After repeated motion stimulation (conditioning), a teststimulus consisting of a single flash at the starting point of the motionpath evoked more sequential spiking of the neurons similar to that evokedby the motion stimulus. This recall effect was found only for teststimulus at the starting point of the motion path, and it persisted for ∼5 min after 100 repeats of motion conditioning. Interestingly, expression ofthis plasticity in awake animals depended on the brain state:conditioning-induced increase in sequential firing was observed during asynchronized (rowsy) state with large-amplitude, low-frequency corticalactivity, but not in the desynchronized (lert) state with high-frequency activity. Such brain state-dependent enhancement ofsequential neuronal spiking may contribute to short-term memory of visualstimulus sequence and perceptual inference based on recent experience. doi:10.1016/j.neures.2010.07.439
S3-7-1-1 Clinical overview of upper limb dysfunction in hemiparetic stroke Ichiro Miyai Neurorehabilitation Research Institute, Morinomiya Hospital Basic and clinical studies have suggested that functional recovery of hemiparetic upper limb depends on use-dependent plasticity of the damaged brain after stroke. Although patterns of functional reorganization and their longitudinal changes are influenced by size and location of lesion, integrity of the ipsilesional descending motor pathway appears to be essential to restore dexterity of the paretic hand. It is still challenging to favorably
Biokinesiology, USC 2 Computer Science, University of Southern California, Los Angeles, CA 90089 3 Departments of Rehabilitation Medicine, Medicine and Cell Biology, Emory University School of Medicine, VA Rehabilitation R&D Center, Atlanta, GA 30322 Although spontaneous use of the more-affected arm and hand after stroke is an important determinant of participation and quality of life, a number of patients exhibit decreases in use following rehabilitative therapy. A previous neurocomputational model predicted that if the dose of therapy is sufficient to bring performance above a certain threshold, training can be stopped. The aim of this study was to test the hypothesis that there exists a threshold for function of the paretic arm and hand after therapy. If function is above this threshold, spontaneous use will increase in the months following therapy. In contrast, if function is below this threshold, spontaneous use will decrease. New computer simulations are presented showing that changes in arm use following therapy depend on a performance threshold. This prediction was tested by reanalyzing the data from the extremity constraint-induced therapy evaluation (EXCITE) trial, phase III randomized controlled trial in which participants received constraint-induced movement therapy for 2 weeks and were tested both 1 week and 1 year after therapy. The results demonstrate that arm and hand function measured immediately after therapy predicts, on average, the long-term change of arm use. Above a functional threshold, use improves. Below this threshold, use decreases. This reanalysis of the EXCITE trial data provides a group threshold above which a majority of patients, but not all, see spontaneous improvement in use following therapy. A goal of our current research is to provide the means to assess when patients reach their individual threshold. We present preliminary data on models that are fitted to individual patient data and allow us to estimate such individual thresholds as well as the effect of therapy on the interactions between performance and use. doi:10.1016/j.neures.2010.07.441
S3-7-1-3 Effect of hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy for functional recovery after stroke Toshiyuki Fujiwara Department of Rehabilitation Medicine, Keio University School of Medicine We devised a therapeutic approach to facilitate the use of the paretic UE in daily life by combining integrated volitional control electrical stimulation (IVES) with a wrist splint, the hybrid assistive neuromuscular dynamic stimulation (HANDS) therapy. IVES can automatically change its stimulation intensity in direct proportion to the changes in voluntary generated EMG amplitude recorded with surface electrodes placed on the target muscle. The stimulation was applied to the paretic finger extensors. Using this assistive stimulation combined with a splint, patients with moderate to severe hemiparesis, who cannot extend their paretic fingers voluntarily, could extend