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Inter-limb transfer of both simple and complex motor skills is maintained in elderly adults
Abstracts / Brain Stimulation 8 (2015) 360e377
group, but not the ST+sham group. No main effects were reported for the a-tDCS group (all p > 0.05). Discussion: The addition of a-tDCS to the iM1 during unilateral strength training prolongs the benefits of cross-education, which may have significant implications for enhancing rehabilitation outcomes following single limb injury or impairment.
179 NIH Pediatric Auditory Brainstem Implant Clinical Trial: Initial Surgical and Audiological Results Eric P. Wilkinson M.D. a, Laurie S. Eisenberg Ph.D. b, Marc S. Schwartz M.D. a, Mark D. Krieger M.D. c, Laurel K. Fisher Ph.D. b, Robert V. Shannon Ph.D. b for the Los Angeles Pediatric ABI Team a House Clinic and Huntington Medical Research Institutes b University of Southern California c Children’s Hospital Los Angeles Introduction: Pediatric auditory brainstem implantation is in its early stages in the United States. US FDA investigational device exemption (IDE) trials are underway. The National Institutes of Health/National Institute on Deafness and Other Communication Disorders (NIDCD) are sponsoring a trial of the auditory brainstem implant in children to assess surgical safety and audiological outcomes. Objective: The Los Angeles Pediatric ABI Team has enrolled patients for the study with cochlear nerve hypoplasia/absence, cochlear aplasia/severe malformation. Three patients are planned to have been implanted in the first study year, and two patients are planned to have been implanted in the second study year. Methods: Five patients in the first two years of the study who meet inclusion criteria for the study have undergone extensive audiological, medical, and radiological assessment. Patients with anatomy suitable for cochlear implantation have undergone cochlear implantation prior to ABI to assess for response to sustained neural stimulation with a cochlear implant prior to proceeding to ABI. Surgical protocols have been developed and modified during the trial to develop a proper standardized technique for pediatric ABI implantation, emphasizing surgical safety as well as maximize audiological outcome. Results: The results of the first five patients from the study will be presented. Surgical safety and initial audiological results will be presented. Conclusion: An NIDCD/NIH pediatric ABI study is underway that hopes to elucidate proper surgical protocols and obtain audiological results in a select group of patients who are suitable candidates for ABI surgery. In patients who have suitable anatomy, a cochlear implant will be undertaken as a first step prior to salvage ABI.
180 Effects of anodal tDCS on corticomotor excitability during acute hypoxia Clare E. Turner a, Winston D. Byblow b, Nicholas Gant a a Exercise Neurometabolism Laboratory b Movement Neuroscience Laboratory, Centre for Brain Research, The University of Auckland, New Zealand Neurons have a limited capacity to store energy and rely on a constant supply of oxygen to support their high energy demands. Hypoxic stress reduces neural energy availability and challenges brain function. Anodal transcranial direct current stimulation (atDCS) of the primary motor cortex can increase global energy uptake (1) and alter corticomotor excitability at rest. This study
363
assessed the effect of a-tDCS on corticomotor excitability during acute hypoxia. Healthy volunteers participated in a double-blind a-tDCS protocol during hypoxia, within a placebo-controlled study of creatine monohydrate supplementation. Neural excitability of the primary motor cortex was assessed using transcranial magnetic stimulation to elicit motor evoked potentials (MEPs) in right first dorsal interosseous (FDI) before and during hypoxia (10% O2; 90 min). Anodal or sham tDCS (1 mA; 12 min) was delivered during hypoxia (anode over left hemisphere FDI hotspot, cathode over right orbit). MEPs were again acquired immediately following a-tDCS. Stimulus-response curves were constructed from normalised MEP amplitudes. The area under the stimulus-response curves was calculated for the normoxic and hypoxic conditions to generate a single SMEP value to define net corticomotor excitability at each timepoint. The change in SMEP was calculated relative to baseline under normoxic conditions for each stimulation condition. SMEP increased under hypoxia relative to baseline (p¼0.01). However, no such increase was observed when a-tDCS was applied compared to sham stimulation (p<0.01). Hypoxic stress compromises the maintenance of resting membrane potentials, increasing corticomotor excitability. This impairment may be offset by a-tDCS via the enhanced global energy uptake that is observed following tDCS (1).
Reference 1. Binkofski F , et al. Brain energy consumption induced by electrical stimulation promotes systemic glucose uptake. Biol. Psychiatry 2011;70:690e5.
181 Inter-limb transfer of both simple and complex motor skills is maintained in elderly adults Daina S.E. Dickins a, Martin V. Sale a, Jason B. Mattingley a,b, Marc R. Kamke a a The Queensland Brain Institute, The University of Queensland, Australia b The School of Psychology, The University of Queensland, Australia Inter-limb transfer refers to the phenomenon whereby unilateral motor-skill training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that older adults exhibit a reduction in the capacity for inter-limb transfer following training on a simple ballistic movement task, but not after training on a complex task. Evidence also suggests that age-related over-activity in bilateral motor cortices may underlie the differential inter-limb transfer evident after simple and complex tasks in elderly adults. To explore this possibility, we directly compared inter-limb transfer in young (18-35 years) and elderly adults (65+ years) after training on a simple (repeated ballistic thumb abduction) and complex (sequential finger-thumb opposition) task. Behavioural performance was used to quantify inter-limb transfer between the dominant (trained) and non-dominant (untrained) hands. The amplitude of motorevoked potentials induced by transcranial magnetic stimulation was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after motor-skill training with simple and complex tasks. Transcranial magnetic stimulation revealed that performance gains in both groups were accompanied by bilateral increases in cortical excitability. Our findings suggest that advancing age does not influence the capacity of elderly adults to exhibit inter-limb transfer after training with the dominant hand. Furthermore, this capacity is not modulated by task complexity.
group, but not the ST+sham group. No main effects were reported for the a-tDCS group (all p > 0.05). Discussion: The addition of a-tDCS to the iM1 during unilateral strength training prolongs the benefits of cross-education, which may have significant implications for enhancing rehabilitation outcomes following single limb injury or impairment.
179 NIH Pediatric Auditory Brainstem Implant Clinical Trial: Initial Surgical and Audiological Results Eric P. Wilkinson M.D. a, Laurie S. Eisenberg Ph.D. b, Marc S. Schwartz M.D. a, Mark D. Krieger M.D. c, Laurel K. Fisher Ph.D. b, Robert V. Shannon Ph.D. b for the Los Angeles Pediatric ABI Team a House Clinic and Huntington Medical Research Institutes b University of Southern California c Children’s Hospital Los Angeles Introduction: Pediatric auditory brainstem implantation is in its early stages in the United States. US FDA investigational device exemption (IDE) trials are underway. The National Institutes of Health/National Institute on Deafness and Other Communication Disorders (NIDCD) are sponsoring a trial of the auditory brainstem implant in children to assess surgical safety and audiological outcomes. Objective: The Los Angeles Pediatric ABI Team has enrolled patients for the study with cochlear nerve hypoplasia/absence, cochlear aplasia/severe malformation. Three patients are planned to have been implanted in the first study year, and two patients are planned to have been implanted in the second study year. Methods: Five patients in the first two years of the study who meet inclusion criteria for the study have undergone extensive audiological, medical, and radiological assessment. Patients with anatomy suitable for cochlear implantation have undergone cochlear implantation prior to ABI to assess for response to sustained neural stimulation with a cochlear implant prior to proceeding to ABI. Surgical protocols have been developed and modified during the trial to develop a proper standardized technique for pediatric ABI implantation, emphasizing surgical safety as well as maximize audiological outcome. Results: The results of the first five patients from the study will be presented. Surgical safety and initial audiological results will be presented. Conclusion: An NIDCD/NIH pediatric ABI study is underway that hopes to elucidate proper surgical protocols and obtain audiological results in a select group of patients who are suitable candidates for ABI surgery. In patients who have suitable anatomy, a cochlear implant will be undertaken as a first step prior to salvage ABI.
180 Effects of anodal tDCS on corticomotor excitability during acute hypoxia Clare E. Turner a, Winston D. Byblow b, Nicholas Gant a a Exercise Neurometabolism Laboratory b Movement Neuroscience Laboratory, Centre for Brain Research, The University of Auckland, New Zealand Neurons have a limited capacity to store energy and rely on a constant supply of oxygen to support their high energy demands. Hypoxic stress reduces neural energy availability and challenges brain function. Anodal transcranial direct current stimulation (atDCS) of the primary motor cortex can increase global energy uptake (1) and alter corticomotor excitability at rest. This study
363
assessed the effect of a-tDCS on corticomotor excitability during acute hypoxia. Healthy volunteers participated in a double-blind a-tDCS protocol during hypoxia, within a placebo-controlled study of creatine monohydrate supplementation. Neural excitability of the primary motor cortex was assessed using transcranial magnetic stimulation to elicit motor evoked potentials (MEPs) in right first dorsal interosseous (FDI) before and during hypoxia (10% O2; 90 min). Anodal or sham tDCS (1 mA; 12 min) was delivered during hypoxia (anode over left hemisphere FDI hotspot, cathode over right orbit). MEPs were again acquired immediately following a-tDCS. Stimulus-response curves were constructed from normalised MEP amplitudes. The area under the stimulus-response curves was calculated for the normoxic and hypoxic conditions to generate a single SMEP value to define net corticomotor excitability at each timepoint. The change in SMEP was calculated relative to baseline under normoxic conditions for each stimulation condition. SMEP increased under hypoxia relative to baseline (p¼0.01). However, no such increase was observed when a-tDCS was applied compared to sham stimulation (p<0.01). Hypoxic stress compromises the maintenance of resting membrane potentials, increasing corticomotor excitability. This impairment may be offset by a-tDCS via the enhanced global energy uptake that is observed following tDCS (1).
Reference 1. Binkofski F , et al. Brain energy consumption induced by electrical stimulation promotes systemic glucose uptake. Biol. Psychiatry 2011;70:690e5.
181 Inter-limb transfer of both simple and complex motor skills is maintained in elderly adults Daina S.E. Dickins a, Martin V. Sale a, Jason B. Mattingley a,b, Marc R. Kamke a a The Queensland Brain Institute, The University of Queensland, Australia b The School of Psychology, The University of Queensland, Australia Inter-limb transfer refers to the phenomenon whereby unilateral motor-skill training induces performance gains in both the trained limb and in the opposite, untrained limb. Evidence indicates that older adults exhibit a reduction in the capacity for inter-limb transfer following training on a simple ballistic movement task, but not after training on a complex task. Evidence also suggests that age-related over-activity in bilateral motor cortices may underlie the differential inter-limb transfer evident after simple and complex tasks in elderly adults. To explore this possibility, we directly compared inter-limb transfer in young (18-35 years) and elderly adults (65+ years) after training on a simple (repeated ballistic thumb abduction) and complex (sequential finger-thumb opposition) task. Behavioural performance was used to quantify inter-limb transfer between the dominant (trained) and non-dominant (untrained) hands. The amplitude of motorevoked potentials induced by transcranial magnetic stimulation was used to investigate excitability changes in bilateral motor cortices. Contrary to predictions, both age groups exhibited performance improvements in both hands after motor-skill training with simple and complex tasks. Transcranial magnetic stimulation revealed that performance gains in both groups were accompanied by bilateral increases in cortical excitability. Our findings suggest that advancing age does not influence the capacity of elderly adults to exhibit inter-limb transfer after training with the dominant hand. Furthermore, this capacity is not modulated by task complexity.