J. Ibanez - Academia.edu (original) (raw)
Papers by J. Ibanez
Journal of Neurophysiology, 2014
Tremor in essential tremor (ET) is generated by pathological oscillations at 4 to 12 Hz, 33 likel... more Tremor in essential tremor (ET) is generated by pathological oscillations at 4 to 12 Hz, 33 likely originating at cerebello-thalamo-cortical pathways. However, the way in which 34 tremor is represented in the output of the spinal cord circuitries is largely unknown 35 because of the difficulties in identifying the behavior of individual motor units from 36 tremulous muscles. By using novel methods for the decomposition of multichannel 37 surface EMG, we provide a systematic analysis of the discharge properties of motor 38 units in 9 ET patients, with concurrent recordings of EEG activity. This analysis 39 allowed inferring the contribution of common synaptic inputs to motor neurons in ET. 40 Motor unit short-term synchronization was significantly greater in ET patients than in 41 healthy subjects. Further, the strong association between the degree of synchronization 42 and the peak in coherence between motor unit spike trains at the tremor frequency 43 indicated that the high synchronization levels were generated mainly by common 44 synaptic inputs specifically at the tremor frequency. The coherence between EEG and 45 motor unit spike trains demonstrated the presence of common cortical input to the motor 46 neurons at the tremor frequency. Nonetheless, the strength of this input was 47 uncorrelated to the net common synaptic input at the tremor frequency, suggesting a 48 contribution of spinal afferents or secondary supraspinal pathways in projecting 49 common input at the tremor frequency. These results provide the first systematic 50 analysis of the neural drive to the muscle in ET and elucidate some of its characteristics 51 that determine the pathological tremulous muscle activity. 52 53
2011 IEEE International Conference on Robotics and Automation, 2011
Tremor constitutes the most common motor disorder, and poses a functional problem to a large numb... more Tremor constitutes the most common motor disorder, and poses a functional problem to a large number of patients. Despite of the considerable experience in tremor management, current treatment based on drugs or surgery does not attain an effective attenuation in 25 % of patients, motivating the need for research in new therapeutic alternatives. In this context, this paper presents the concept design, development, and preliminary validation of a soft wearable robot for tremor assessment and suppression. The TREMOR neurorobot comprises a Brain Neural Computer Interface that monitors the whole neuromusculoskeletal system, aiming at characterizing both voluntary movement and tremor, and a Functional Electrical Stimulation system that compensates for tremulous movements without impeding the user perform functional tasks. First results demonstrate the performance of the TREMOR neurorobot as a novel means of assessing and attenuating pathological tremors.
PLoS ONE, 2014
Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4-12 Hz... more Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4-12 Hz. Previous studies suggest that the tremor activity originates in the cerebello-thalamocortical pathways. Alprazolam is a short-acting benzodiazepine that attenuates tremors in ET. The mechanisms that mediate the therapeutic action of alprazolam are unknown; however, in healthy subjects, benzodiazepines increase cortical beta activity. In this study, we investigated the effect of alprazolam both on beta and tremor-related cortical activity and on alterations in tremor presentation in ET patients. Therefore, we characterised the dynamics of tremor and cortical activity in ET patients after alprazolam intake. We recorded hand tremors and contralateral cortical activity in four recordings before and after a single dose of alprazolam. We then computed the changes in tremors, cortico-muscular coherence, and cortical activity at the tremor frequency and in the beta band. Alprazolam significantly attenuated tremors (EMG: 76.2 ± 22.68%), decreased cortical activity in the tremor frequency range and increased cortical beta activity in all patients (P<0.05). At the same time, the cortico-muscular coherence at the tremor frequency became non-significant (P<0.05). We also found a significant correlation (r = 0.757, P<0.001) between the reduction in tremor severity and the increased ratio of cortical activity in the beta band to the activity observed in the tremor frequency range. This study provides the first quantitative analysis of tremor reduction following alprazolam intake. We observed that the tremor severity decreased in association with an increased ratio of beta to tremor-related cortical activity. We hypothesise that the increase in cortical beta activity may act as a blocking mechanism and may dampen the pathological oscillatory activity, which in turn attenuates the observed tremor.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2010
Tremor constitutes the most common movement disorder; in fact 14.5% of population between 50 to 8... more Tremor constitutes the most common movement disorder; in fact 14.5% of population between 50 to 89 years old suffers from it. Moreover, 65% of patients with upper limb tremor report disability when performing their activities of daily living (ADL). Unfortunately, 25% of patients do not respond to drugs or neurosurgery. In this regard, TREMOR project proposes functional compensation of upper limb tremors with a soft wearable robot that applies biomechanical loads through functional electrical stimulation (FES) of muscles. This wearable robot is driven by a Brain Neural Computer Interface (BNCI). This paper presents a multimodal BCI to assess generation, transmission and execution of both volitional and tremorous movements based on electroencephalography (EEG), electromyography (EMG) and inertial sensors (IMUs). These signals are combined to obtain: 1) the intention to perform a voluntary movement from cortical activity (EEG), 2) tremor onset, and an estimation of tremor frequency fro...
IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews), 2000
Tremor is the most prevalent movement disorder, and its incidence is increasing with aging. In sp... more Tremor is the most prevalent movement disorder, and its incidence is increasing with aging. In spite of the numerous therapeutic solutions available, 65 % of those suffering from upper limb tremor report serious difficulties during their daily living. This gives rise to research on different treatment alternatives, amongst which wearable robots that apply selective mechanical loads constitute an appealing approach. In this context, the current work presents a multimodal Human-Robot Interface to drive a neuroprosthesis for tremor management. Our approach relies on the precise characterization of the tremor to modulate a functional electrical stimulation system that compensates for it. The neuroprosthesis is triggered by the detection of the intention to move derived from the analysis of electroencephalographic activity, which provides a natural interface with the user. When a prediction is delivered, surface electromyography serves to detect the actual onset of the tremor in the presence of volitional activity. This information in turn triggers the stimulation, which relies on tremor parameters amplitude and frequency derived from a pair of inertial sensors that record the kinematics of the affected joint. Surface electromyography also yields a first characterization of the tremor, together with precise information on the preferred stimulation site. Apart from allowing for an optimized performance of the system, our multimodal approach permits implementing redundant methods to both enhance the reliability of the system, and adapt to the specific needs of different users. Results with a representative group of patients illustrate the performance of the interface here presented and demonstrate its feasibility.
Biomedical Signal Processing and Control, 2013
Patients with tremor can benefit from wearable robots managing their tremor during daily living. ... more Patients with tremor can benefit from wearable robots managing their tremor during daily living. To achieve this, the interfaces controlling such robotic systems must be able to estimate the user's intention to move and to distinguish it from the undesired tremor. In this context, analysis of electroencephalographic activity is of special interest, since it provides information on the planning and execution of voluntary movements. This paper proposes an adaptive and asynchronous EEG-based system for online detection of the intention to move in patients with tremor. An experimental protocol with separated self-paced wrist extensions was used to test the ability of the system to detect the intervals preceding voluntary movements. Six healthy subjects and four essential tremor patients took part in the experiments. The system predicted 60±10 % of the movements with the control subjects and 42±27 % of the movements with the patients.
Journal of Neurophysiology, 2014
Tremor in essential tremor (ET) is generated by pathological oscillations at 4 to 12 Hz, 33 likel... more Tremor in essential tremor (ET) is generated by pathological oscillations at 4 to 12 Hz, 33 likely originating at cerebello-thalamo-cortical pathways. However, the way in which 34 tremor is represented in the output of the spinal cord circuitries is largely unknown 35 because of the difficulties in identifying the behavior of individual motor units from 36 tremulous muscles. By using novel methods for the decomposition of multichannel 37 surface EMG, we provide a systematic analysis of the discharge properties of motor 38 units in 9 ET patients, with concurrent recordings of EEG activity. This analysis 39 allowed inferring the contribution of common synaptic inputs to motor neurons in ET. 40 Motor unit short-term synchronization was significantly greater in ET patients than in 41 healthy subjects. Further, the strong association between the degree of synchronization 42 and the peak in coherence between motor unit spike trains at the tremor frequency 43 indicated that the high synchronization levels were generated mainly by common 44 synaptic inputs specifically at the tremor frequency. The coherence between EEG and 45 motor unit spike trains demonstrated the presence of common cortical input to the motor 46 neurons at the tremor frequency. Nonetheless, the strength of this input was 47 uncorrelated to the net common synaptic input at the tremor frequency, suggesting a 48 contribution of spinal afferents or secondary supraspinal pathways in projecting 49 common input at the tremor frequency. These results provide the first systematic 50 analysis of the neural drive to the muscle in ET and elucidate some of its characteristics 51 that determine the pathological tremulous muscle activity. 52 53
2011 IEEE International Conference on Robotics and Automation, 2011
Tremor constitutes the most common motor disorder, and poses a functional problem to a large numb... more Tremor constitutes the most common motor disorder, and poses a functional problem to a large number of patients. Despite of the considerable experience in tremor management, current treatment based on drugs or surgery does not attain an effective attenuation in 25 % of patients, motivating the need for research in new therapeutic alternatives. In this context, this paper presents the concept design, development, and preliminary validation of a soft wearable robot for tremor assessment and suppression. The TREMOR neurorobot comprises a Brain Neural Computer Interface that monitors the whole neuromusculoskeletal system, aiming at characterizing both voluntary movement and tremor, and a Functional Electrical Stimulation system that compensates for tremulous movements without impeding the user perform functional tasks. First results demonstrate the performance of the TREMOR neurorobot as a novel means of assessing and attenuating pathological tremors.
PLoS ONE, 2014
Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4-12 Hz... more Essential tremor (ET) is characterised by postural and action tremors with a frequency of 4-12 Hz. Previous studies suggest that the tremor activity originates in the cerebello-thalamocortical pathways. Alprazolam is a short-acting benzodiazepine that attenuates tremors in ET. The mechanisms that mediate the therapeutic action of alprazolam are unknown; however, in healthy subjects, benzodiazepines increase cortical beta activity. In this study, we investigated the effect of alprazolam both on beta and tremor-related cortical activity and on alterations in tremor presentation in ET patients. Therefore, we characterised the dynamics of tremor and cortical activity in ET patients after alprazolam intake. We recorded hand tremors and contralateral cortical activity in four recordings before and after a single dose of alprazolam. We then computed the changes in tremors, cortico-muscular coherence, and cortical activity at the tremor frequency and in the beta band. Alprazolam significantly attenuated tremors (EMG: 76.2 ± 22.68%), decreased cortical activity in the tremor frequency range and increased cortical beta activity in all patients (P<0.05). At the same time, the cortico-muscular coherence at the tremor frequency became non-significant (P<0.05). We also found a significant correlation (r = 0.757, P<0.001) between the reduction in tremor severity and the increased ratio of cortical activity in the beta band to the activity observed in the tremor frequency range. This study provides the first quantitative analysis of tremor reduction following alprazolam intake. We observed that the tremor severity decreased in association with an increased ratio of beta to tremor-related cortical activity. We hypothesise that the increase in cortical beta activity may act as a blocking mechanism and may dampen the pathological oscillatory activity, which in turn attenuates the observed tremor.
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference, 2010
Tremor constitutes the most common movement disorder; in fact 14.5% of population between 50 to 8... more Tremor constitutes the most common movement disorder; in fact 14.5% of population between 50 to 89 years old suffers from it. Moreover, 65% of patients with upper limb tremor report disability when performing their activities of daily living (ADL). Unfortunately, 25% of patients do not respond to drugs or neurosurgery. In this regard, TREMOR project proposes functional compensation of upper limb tremors with a soft wearable robot that applies biomechanical loads through functional electrical stimulation (FES) of muscles. This wearable robot is driven by a Brain Neural Computer Interface (BNCI). This paper presents a multimodal BCI to assess generation, transmission and execution of both volitional and tremorous movements based on electroencephalography (EEG), electromyography (EMG) and inertial sensors (IMUs). These signals are combined to obtain: 1) the intention to perform a voluntary movement from cortical activity (EEG), 2) tremor onset, and an estimation of tremor frequency fro...
IEEE Transactions on Systems, Man, and Cybernetics, Part C (Applications and Reviews), 2000
Tremor is the most prevalent movement disorder, and its incidence is increasing with aging. In sp... more Tremor is the most prevalent movement disorder, and its incidence is increasing with aging. In spite of the numerous therapeutic solutions available, 65 % of those suffering from upper limb tremor report serious difficulties during their daily living. This gives rise to research on different treatment alternatives, amongst which wearable robots that apply selective mechanical loads constitute an appealing approach. In this context, the current work presents a multimodal Human-Robot Interface to drive a neuroprosthesis for tremor management. Our approach relies on the precise characterization of the tremor to modulate a functional electrical stimulation system that compensates for it. The neuroprosthesis is triggered by the detection of the intention to move derived from the analysis of electroencephalographic activity, which provides a natural interface with the user. When a prediction is delivered, surface electromyography serves to detect the actual onset of the tremor in the presence of volitional activity. This information in turn triggers the stimulation, which relies on tremor parameters amplitude and frequency derived from a pair of inertial sensors that record the kinematics of the affected joint. Surface electromyography also yields a first characterization of the tremor, together with precise information on the preferred stimulation site. Apart from allowing for an optimized performance of the system, our multimodal approach permits implementing redundant methods to both enhance the reliability of the system, and adapt to the specific needs of different users. Results with a representative group of patients illustrate the performance of the interface here presented and demonstrate its feasibility.
Biomedical Signal Processing and Control, 2013
Patients with tremor can benefit from wearable robots managing their tremor during daily living. ... more Patients with tremor can benefit from wearable robots managing their tremor during daily living. To achieve this, the interfaces controlling such robotic systems must be able to estimate the user's intention to move and to distinguish it from the undesired tremor. In this context, analysis of electroencephalographic activity is of special interest, since it provides information on the planning and execution of voluntary movements. This paper proposes an adaptive and asynchronous EEG-based system for online detection of the intention to move in patients with tremor. An experimental protocol with separated self-paced wrist extensions was used to test the ability of the system to detect the intervals preceding voluntary movements. Six healthy subjects and four essential tremor patients took part in the experiments. The system predicted 60±10 % of the movements with the control subjects and 42±27 % of the movements with the patients.