Browsing by Author "Nishimura, Yukio"
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Item Influence of trans-spinal magnetic stimulation in electrophysiological recordings for closed-loop rehabilitative systems(Institute of Electrical and Electronics Engineers Inc., 2017-09-13) Insausti-Delgado, Ainhoa; Lopez-Larraz, Eduardo; Bibian, Carlos; Nishimura, Yukio; Birbaumer, Niels; Ramos-Murguialday, Ander; Medical TechnologiesRecent studies have shown the feasibility of spinal cord stimulation (SCS) for motor rehabilitation. Currently, there is an increasing interest in developing closed-loop systems employing SCS for lower-limb recovery. These closed-loop systems are based on the use of neurophysiological signals to modulate the stimulation. It is known that electromagnetic stimulation can introduce undesirable noise to the electrophysiological recordings. However, there is little evidence about how electroencephalographic (EEG) or electromyographic (EMG) activities are corrupted when a trans-spinal magnetic stimulation is applied. This paper studies the effects of magnetic SCS in EEG and EMG activity. Furthermore, a median filter is proposed to ameliorate the effects of the artifacts, and to preserve the neural activity. Our results show that SCS can affect both EEG and EMG, and that, while the median filter works well to clean the EEG activity, it did not improve the contaminations of the EMG activity. The obtained results underline the need of cleaning EMG and EEG signals contaminated by SCS, which is essential for optimal closed-loop rehabilitation.Item Non-invasive brain-spine interface: Continuous control of trans-spinal magnetic stimulation using EEG(2022-10-31) Insausti-Delgado, Ainhoa; López-Larraz, Eduardo; Nishimura, Yukio; Ziemann, Ulf; Ramos-Murguialday, Ander; Medical TechnologiesBrain-controlled neuromodulation has emerged as a promising tool to promote functional recovery in patients with motor disorders. Brain-machine interfaces exploit this neuromodulatory strategy and could be used for restoring voluntary control of lower limbs. In this work, we propose a non-invasive brain-spine interface (BSI) that processes electroencephalographic (EEG) activity to volitionally control trans-spinal magnetic stimulation (ts-MS), as an approach for lower-limb neurorehabilitation. This novel platform allows to contingently connect motor cortical activation during leg motor imagery with the activation of leg muscles via ts-MS. We tested this closed-loop system in 10 healthy participants using different stimulation conditions. This BSI efficiently removed stimulation artifacts from EEG regardless of ts-MS intensity used, allowing continuous monitoring of cortical activity and real-time closed-loop control of ts-MS. Our BSI induced afferent and efferent evoked responses, being this activation ts-MS intensity-dependent. We demonstrated the feasibility, safety and usability of this non-invasive BSI. The presented system represents a novel non-invasive means of brain-controlled neuromodulation and opens the door towards its integration as a therapeutic tool for lower-limb rehabilitation.Item Quantifying the effect of trans-spinal magnetic stimulation on spinal excitability(IEEE Computer Society, 2019-05-16) Insausti-Delgado, Ainhoa; Lopez-Larraz, Eduardo; Nishimura, Yukio; Birbaumer, Niels; Ziemann, Ulf; Ramos-Murguialday, Ander; Medical TechnologiesDuring the last decades, spinal cord stimulation (SCS) has attracted much attention due to its capability to modulate the motor and sensory networks. The potential of this technique has been proved, and several investigations have focused on applying it for restoring lower limb function. The majority of SCS approaches are based on electrical stimulation, and few studies have explored magnetic fields for non-invasive SCS. This paper presents a trans-spinal magnetic stimulation (ts-MS) protocol and studies its effects on spinal circuits with seven healthy subjects, considering central and peripheral nervous systems. Motor evoked potentials (MEP) and trans-spinal motor evoked potentials (ts-MEP) were assessed before and after the ts-MS intervention to characterize excitatory responses. After the intervention, we found an increase of almost 30% (not statistically significant) in MEP amplitude, but no changes in ts-MEP amplitude. Further research is required to confirm, in a larger population of subjects, the potential of this technology, which could be used to improve rehabilitation therapies for patients with motor disabilities.