- Email: [email protected]
13. Desynchronisation of neuronal network activity in traumatic brain injury
Society Proceedings / Clinical Neurophysiology 120 (2009) e9–e88
e11
11. The impact of stimulus properties on low- and high-frequency median nerve SEPs—R. Gobbelé, A. Dieckhöfer, H. Buchner, T.D. Waberski (Universitätsklinik Aachen, Neurologie, Aachen, Germany)
with our hypothesis. These findings suggest that this interventional strategy in combination with customary rehabilitative treatments could significantly improve the outcome of neurorehabilitation in the chronic stage after stroke.
Questioning whether the stimulation properties in median nerve SEPs show interactions, multichannel recordings were performed in a three-factorial repeated measures design with the parameters (i) eyes opened vs. eyes closed, (ii) stimulation intensity above motor threshold (MT) vs. intensity sub MT, (iii) stimulation rate 0,5Hz vs. 9Hz, resulting in SEPs recorded during eight different conditions. Varying the stimulation intensity revealed an impact on the amplitude and the latency of the N20 source activity and on the amplitude, the duration and the number of peaks of the high-frequency oscillatory (HFO) sources. Modifying the stimulation rate led to an effect on the amplitude and latency of the N20 and on the amplitude of the HFO sources. The condition opened/closed eyes had an impact on the duration and number of HFO sources. No relevant interactions between the stimulation properties were found. In consequence varying one stimulus parameter leads to a saturation of the low- as well as high-frequency SEP components. Thus, the careful choice of stimulation parameters is a condition precedent for reasonable data interpretation.
doi:10.1016/j.clinph.2008.07.015
doi:10.1016/j.clinph.2008.07.014
12. Levodopa improves procedural motor learning in chronic stroke patients—N. Rösser, A. Flöel (Universitätsklinikum Münster, Klinik und Poliklinik für Neurologie, Münster, Germany) Objective: Stroke is a leading cause of motor disability. Recovery of motor function after stroke often remains incomplete despite physiotherapy. This study was designed to test the hypothesis that administration of dopamine (DA) precursor levodopa improves procedural motor learning in patients with residual motor deficits in the chronic phase after stroke ( one year after stroke). Procedural motor learning is defined as the ability to acquire novel movement patterns gradually through practice. Design: A double-blind, placebo-controlled, randomized crossover design was used. Setting: Department of Neurology, University of Muenster, Germany. Patients: Eighteen stroke patients (age range: 53–78 years, five female). Interventions: Patients received three doses of levodopa (100 mg levodopa + 25 mg carbidopa) or placebo prior to one session of procedural motor learning. Main outcome measures: Procedural motor learning using the paretic hand was assessed by a modified version of the serial reaction time (SRT) task with a probabilistic sequence. Primary outcome measure was the difference in reaction times (RTs) between random and sequential elements. Results: Levodopa significantly improved our primary outcome measure, procedural motor learning, compared to placebo (p < 0.05). Reaction times to random elements, analysis of error rates, psychophysical assessments, as well as performance in a simple motor task were comparable between conditions, indicating that better learning under levodopa was not due to the differences in response styles, arousal, mood, or motor reaction time, but was due to levodopa, which modulated learning. Conclusions: Our results demonstrate that levodopa may improve procedural motor learning in chronic stroke patients, in line
13. Desynchronisation of neuronal network activity in traumatic brain injury—F. Otto 1, J. Opatz 1, R. Hartmann 2, D. Willbold 2, E. Donauer 3, M. Siebler 1 (1 Universitätsklinik Düsseldorf, Neurologie, Düsseldorf, Germany, 2 Forschungszentrum, Jülich, Germany, 3 MediClin, Plau am See, Germany) Traumatic brain injury (TBI) is the main cause for mortality and long-time disability in young adults. Apart from structural lesions, release of neuroactive substances has been considered to cause functional neuronal disturbances. The composition of cerebrospinal fluid (CSF) from patients with TBI is often modified, but the functional impact of this modified CSF is still not fully investigated. We therefore tested the functional impact of physiologic and modified CSF on the electrophysiological parameters of neuronal networks. Cryopreserved embryonic rat cortex neurons were thawed and plated on multielectrode arrays. Spontaneous extracellular network activity was sampled simultaneously from 60 planar microelectrodes. CSF was obtained for diagnostic purpose from patients with TBI by external ventricular drain or from control subjects with other neurologic disease (OND) by lumbar puncture. Surplus CSF that was no longer required for standard diagnostics was centrifuged, aliquoted and stored at 35 °C. Within three weeks, cryopreserved embryonic neurons formed a neuritic network with a stable and synchronous spontaneous network activity in artificial CSF (ACSF in mM: NaCl 150, KCl 3,CaCl2 1, MgCl2 1, HEPES 10, Glucose 10, pH 7.4). Application of pure human CSF is well tolerated by cryopreserved rat neurons. In comparison to ACSF, OND–CSF (pH 7.4–7.5) significantly enhanced network activity by increasing the spike rate per minute and burst rate per minute threefold without affecting the synchronicity. TBI–CSF (ph 7.4–7.5) modulated network activity by means of inhibition and desynchronisation. This effect could partly be reversed with the application of NMDA-antagonist APV, indicating a relevant glutamatergic impact of TBI–CSF. TBI– CSF and OND–CSF differed in NMR-spectroscopy in several spectra as well as in concentration of total protein and lactate, but not in the concentration of electrolytes (sodium, calcium, magnesium and potassium). Our study indicates that TBI–CSF contains several neuroactive substances rather than one acitve substance. Detailed analysis will determine the origin of these factors and might help in preventing and treating functional neuronal disturbances in TBI. doi:10.1016/j.clinph.2008.07.016
15. Reward facilitates tactile judgments and modulates hemodynamic responses in human primary somatosensory cortex—B. Pleger 1, F. Blankenburg 1, C. Ruff 2, J. Driver 2, R. Dolan 1 (1 Institute of Neurology, UCL, Wellcome Trust Centre for Neuroimaging, London, UK, 2 UCL Institute of Cognitive Neuroscience, London, UK) Effects of reward on action are well established, but possible effects on sensory function are less well explored. Here we assessed
e11
11. The impact of stimulus properties on low- and high-frequency median nerve SEPs—R. Gobbelé, A. Dieckhöfer, H. Buchner, T.D. Waberski (Universitätsklinik Aachen, Neurologie, Aachen, Germany)
with our hypothesis. These findings suggest that this interventional strategy in combination with customary rehabilitative treatments could significantly improve the outcome of neurorehabilitation in the chronic stage after stroke.
Questioning whether the stimulation properties in median nerve SEPs show interactions, multichannel recordings were performed in a three-factorial repeated measures design with the parameters (i) eyes opened vs. eyes closed, (ii) stimulation intensity above motor threshold (MT) vs. intensity sub MT, (iii) stimulation rate 0,5Hz vs. 9Hz, resulting in SEPs recorded during eight different conditions. Varying the stimulation intensity revealed an impact on the amplitude and the latency of the N20 source activity and on the amplitude, the duration and the number of peaks of the high-frequency oscillatory (HFO) sources. Modifying the stimulation rate led to an effect on the amplitude and latency of the N20 and on the amplitude of the HFO sources. The condition opened/closed eyes had an impact on the duration and number of HFO sources. No relevant interactions between the stimulation properties were found. In consequence varying one stimulus parameter leads to a saturation of the low- as well as high-frequency SEP components. Thus, the careful choice of stimulation parameters is a condition precedent for reasonable data interpretation.
doi:10.1016/j.clinph.2008.07.015
doi:10.1016/j.clinph.2008.07.014
12. Levodopa improves procedural motor learning in chronic stroke patients—N. Rösser, A. Flöel (Universitätsklinikum Münster, Klinik und Poliklinik für Neurologie, Münster, Germany) Objective: Stroke is a leading cause of motor disability. Recovery of motor function after stroke often remains incomplete despite physiotherapy. This study was designed to test the hypothesis that administration of dopamine (DA) precursor levodopa improves procedural motor learning in patients with residual motor deficits in the chronic phase after stroke ( one year after stroke). Procedural motor learning is defined as the ability to acquire novel movement patterns gradually through practice. Design: A double-blind, placebo-controlled, randomized crossover design was used. Setting: Department of Neurology, University of Muenster, Germany. Patients: Eighteen stroke patients (age range: 53–78 years, five female). Interventions: Patients received three doses of levodopa (100 mg levodopa + 25 mg carbidopa) or placebo prior to one session of procedural motor learning. Main outcome measures: Procedural motor learning using the paretic hand was assessed by a modified version of the serial reaction time (SRT) task with a probabilistic sequence. Primary outcome measure was the difference in reaction times (RTs) between random and sequential elements. Results: Levodopa significantly improved our primary outcome measure, procedural motor learning, compared to placebo (p < 0.05). Reaction times to random elements, analysis of error rates, psychophysical assessments, as well as performance in a simple motor task were comparable between conditions, indicating that better learning under levodopa was not due to the differences in response styles, arousal, mood, or motor reaction time, but was due to levodopa, which modulated learning. Conclusions: Our results demonstrate that levodopa may improve procedural motor learning in chronic stroke patients, in line
13. Desynchronisation of neuronal network activity in traumatic brain injury—F. Otto 1, J. Opatz 1, R. Hartmann 2, D. Willbold 2, E. Donauer 3, M. Siebler 1 (1 Universitätsklinik Düsseldorf, Neurologie, Düsseldorf, Germany, 2 Forschungszentrum, Jülich, Germany, 3 MediClin, Plau am See, Germany) Traumatic brain injury (TBI) is the main cause for mortality and long-time disability in young adults. Apart from structural lesions, release of neuroactive substances has been considered to cause functional neuronal disturbances. The composition of cerebrospinal fluid (CSF) from patients with TBI is often modified, but the functional impact of this modified CSF is still not fully investigated. We therefore tested the functional impact of physiologic and modified CSF on the electrophysiological parameters of neuronal networks. Cryopreserved embryonic rat cortex neurons were thawed and plated on multielectrode arrays. Spontaneous extracellular network activity was sampled simultaneously from 60 planar microelectrodes. CSF was obtained for diagnostic purpose from patients with TBI by external ventricular drain or from control subjects with other neurologic disease (OND) by lumbar puncture. Surplus CSF that was no longer required for standard diagnostics was centrifuged, aliquoted and stored at 35 °C. Within three weeks, cryopreserved embryonic neurons formed a neuritic network with a stable and synchronous spontaneous network activity in artificial CSF (ACSF in mM: NaCl 150, KCl 3,CaCl2 1, MgCl2 1, HEPES 10, Glucose 10, pH 7.4). Application of pure human CSF is well tolerated by cryopreserved rat neurons. In comparison to ACSF, OND–CSF (pH 7.4–7.5) significantly enhanced network activity by increasing the spike rate per minute and burst rate per minute threefold without affecting the synchronicity. TBI–CSF (ph 7.4–7.5) modulated network activity by means of inhibition and desynchronisation. This effect could partly be reversed with the application of NMDA-antagonist APV, indicating a relevant glutamatergic impact of TBI–CSF. TBI– CSF and OND–CSF differed in NMR-spectroscopy in several spectra as well as in concentration of total protein and lactate, but not in the concentration of electrolytes (sodium, calcium, magnesium and potassium). Our study indicates that TBI–CSF contains several neuroactive substances rather than one acitve substance. Detailed analysis will determine the origin of these factors and might help in preventing and treating functional neuronal disturbances in TBI. doi:10.1016/j.clinph.2008.07.016
15. Reward facilitates tactile judgments and modulates hemodynamic responses in human primary somatosensory cortex—B. Pleger 1, F. Blankenburg 1, C. Ruff 2, J. Driver 2, R. Dolan 1 (1 Institute of Neurology, UCL, Wellcome Trust Centre for Neuroimaging, London, UK, 2 UCL Institute of Cognitive Neuroscience, London, UK) Effects of reward on action are well established, but possible effects on sensory function are less well explored. Here we assessed