Stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with neuromuscular electrical stimulation (NMES) where active cortical participation in rehabilitation procedures may be facilitated by driving NMES with electromyogram (EMG), electrooculogram (EOG), and electroencephalogram (EEG) derived biopotentials, that represent simultaneous volitional effort and task engagement. During the visuomotor standing balance task, we propose that gaze-interaction (e.g., fixation duration, pupil diameter, blink rate) with the visual stimuli can be a measure of task engagement which can be used to adapt task difficulty to facilitate post-stroke residual visuomotor function. Here, the elapsed time between the last visual fixation to the target and the initiation of the motor response, known as the quiet eye (QE) period, has emerged as a characteristic of higher levels of performance. In this article, we discuss this novel interactive therapy paradigm consisting of a low-cost static posturography system combined with engagement-sensitive volitionally driven NMES for post-stroke balance rehabilitation.
{"title":"Engagement-sensitive interactive neuromuscular electrical therapy system for post-stroke balance rehabilitation - a concept study","authors":"Deepesh Kumar, Gorish Aggarwal, Rishabh Sehgal, Abhijit Das, U. Lahiri, Anirban Dutta","doi":"10.1109/NER.2015.7146592","DOIUrl":"https://doi.org/10.1109/NER.2015.7146592","url":null,"abstract":"Stroke is caused when an artery carrying blood from heart to an area in the brain bursts or a clot obstructs the blood flow thereby preventing delivery of oxygen and nutrients. About half of the stroke survivors are left with some degree of disability. Neuroplasticity is involved in post-stroke functional disturbances, but also in rehabilitation. Beneficial neuroplastic changes may be facilitated with neuromuscular electrical stimulation (NMES) where active cortical participation in rehabilitation procedures may be facilitated by driving NMES with electromyogram (EMG), electrooculogram (EOG), and electroencephalogram (EEG) derived biopotentials, that represent simultaneous volitional effort and task engagement. During the visuomotor standing balance task, we propose that gaze-interaction (e.g., fixation duration, pupil diameter, blink rate) with the visual stimuli can be a measure of task engagement which can be used to adapt task difficulty to facilitate post-stroke residual visuomotor function. Here, the elapsed time between the last visual fixation to the target and the initiation of the motor response, known as the quiet eye (QE) period, has emerged as a characteristic of higher levels of performance. In this article, we discuss this novel interactive therapy paradigm consisting of a low-cost static posturography system combined with engagement-sensitive volitionally driven NMES for post-stroke balance rehabilitation.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127944056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146634
R. Roy, S. Bonnet, S. Charbonnier, A. Campagne
Mental state monitoring is a topical issue in neuroengineering, more particularly for passive brain-computer interface (pBCI) applications. One of the mental states that are currently under focus is mental workload. The level of workload can be estimated from electroencephalographic activity (EEG) and markers derived from this signal. In active BCI applications, a well-known neurophysiological marker, the event-related potential (ERP), is commonly enhanced using a spatial filtering step. In this study, we evaluated how a spatial filtering method such as the xDAWN algorithm could improve mental workload classification performance. Twenty participants performed a Sternberg memory task for 18 minutes with pseudorandomized trials of low vs. high workload (2/6 digits to memorize). Three signal processing chains were compared on their performance to estimate mental workload from the single-trial ERPs of the test item (i.e. present/absent in the memorized list). All 3 included an FLDA classifier with a shrinkage covariance estimation and a 10-fold cross-validation. One chain used the ERPs of a relevant electrode for workload estimation (Cz) and the 2 others used the ERPs of the 32 electrodes and an xDAWN spatial filtering step with either 1 or 2 virtual electrodes kept for classification. Statistical analyses revealed that spatial filtering significantly improved mental workload estimation, with up to 98% of correct classification using the xDAWN algorithm and 2 virtual electrodes.
{"title":"Enhancing single-trial mental workload estimation through xDAWN spatial filtering","authors":"R. Roy, S. Bonnet, S. Charbonnier, A. Campagne","doi":"10.1109/NER.2015.7146634","DOIUrl":"https://doi.org/10.1109/NER.2015.7146634","url":null,"abstract":"Mental state monitoring is a topical issue in neuroengineering, more particularly for passive brain-computer interface (pBCI) applications. One of the mental states that are currently under focus is mental workload. The level of workload can be estimated from electroencephalographic activity (EEG) and markers derived from this signal. In active BCI applications, a well-known neurophysiological marker, the event-related potential (ERP), is commonly enhanced using a spatial filtering step. In this study, we evaluated how a spatial filtering method such as the xDAWN algorithm could improve mental workload classification performance. Twenty participants performed a Sternberg memory task for 18 minutes with pseudorandomized trials of low vs. high workload (2/6 digits to memorize). Three signal processing chains were compared on their performance to estimate mental workload from the single-trial ERPs of the test item (i.e. present/absent in the memorized list). All 3 included an FLDA classifier with a shrinkage covariance estimation and a 10-fold cross-validation. One chain used the ERPs of a relevant electrode for workload estimation (Cz) and the 2 others used the ERPs of the 32 electrodes and an xDAWN spatial filtering step with either 1 or 2 virtual electrodes kept for classification. Statistical analyses revealed that spatial filtering significantly improved mental workload estimation, with up to 98% of correct classification using the xDAWN algorithm and 2 virtual electrodes.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131379794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146593
B. Edelman, Bryan S. Baxter, B. He
Current EEG based brain computer interface (BCI) systems have achieved successful control in up to 3 dimensions; however, the current sensor-based paradigm is not well suited for many rehabilitative and recreational applications that require motor imagination (MI) tasks of fine motor movements to be recognized. Therefore there is a great need to find complex MI tasks that are intuitive for BCI users to perform and that can be classified with high accuracy. In this paper we present our results on classifying four MI tasks of the right hand, flexion, extension, supination and pronation using a novel EEG source imaging approach. Using this approach we were able to improve the four-class classification of the four tasks by nearly 10% as compared to traditional sensor-based techniques.
{"title":"Decoding and mapping of right hand motor imagery tasks using EEG source imaging","authors":"B. Edelman, Bryan S. Baxter, B. He","doi":"10.1109/NER.2015.7146593","DOIUrl":"https://doi.org/10.1109/NER.2015.7146593","url":null,"abstract":"Current EEG based brain computer interface (BCI) systems have achieved successful control in up to 3 dimensions; however, the current sensor-based paradigm is not well suited for many rehabilitative and recreational applications that require motor imagination (MI) tasks of fine motor movements to be recognized. Therefore there is a great need to find complex MI tasks that are intuitive for BCI users to perform and that can be classified with high accuracy. In this paper we present our results on classifying four MI tasks of the right hand, flexion, extension, supination and pronation using a novel EEG source imaging approach. Using this approach we were able to improve the four-class classification of the four tasks by nearly 10% as compared to traditional sensor-based techniques.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131925538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146702
Agamemnon Krasoulis, S. Vijayakumar, K. Nazarpour
The reconstruction of finger movement activity from surface electromyography (sEMG) has been proposed for the proportional and simultaneous myoelectric control of multiple degrees-of-freedom (DOFs). In this paper, we propose a framework for assessing decoding performance on novel movements, that is movements not included in the training dataset. We then use our proposed framework to compare the performance of linear and kernel ridge regression for the reconstruction of finger movement from sEMG and accelerometry. Our findings provide evidence that, although the performance of the non-linear method is superior for movements seen by the decoder during the training phase, the performance of the two algorithms is comparable when generalizing to novel movements.
{"title":"Evaluation of regression methods for the continuous decoding of finger movement from surface EMG and accelerometry","authors":"Agamemnon Krasoulis, S. Vijayakumar, K. Nazarpour","doi":"10.1109/NER.2015.7146702","DOIUrl":"https://doi.org/10.1109/NER.2015.7146702","url":null,"abstract":"The reconstruction of finger movement activity from surface electromyography (sEMG) has been proposed for the proportional and simultaneous myoelectric control of multiple degrees-of-freedom (DOFs). In this paper, we propose a framework for assessing decoding performance on novel movements, that is movements not included in the training dataset. We then use our proposed framework to compare the performance of linear and kernel ridge regression for the reconstruction of finger movement from sEMG and accelerometry. Our findings provide evidence that, although the performance of the non-linear method is superior for movements seen by the decoder during the training phase, the performance of the two algorithms is comparable when generalizing to novel movements.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"124 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132367778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146642
K. Ng, A. Cutrone, S. Bossi, S. Nag, Ignacio Delgado-Martínez, Swathi Sheshadri, Claire A. Poulard, Y. Xu, S. Yen, N. Thakor
Thin-film longitudinal intrafascicular electrodes (tf-LIFE) are widely used for peripheral nerve recordings. tf-LIFEs are also promising electrodes for neural signal acquisition in future peripheral nerve prostheses. However, common mode signal interference, and electrical artifacts originating from long wire leads and wire movement are known problems encountered when using such electrodes, which lead to degradation in the recording quality. Here, we report an active tf-LIFE electrode implemented by integrating a neural amplifier chip die in close proximity to a tf-LIFE electrode. Consuming only 1mW and measuring 37 mm×7.2 mm×2.4 mm, this active tf-LIFE electrode creates a reliable connection and considerably shortens the distance between the electrode site and neural amplifier. This active electrode has demonstrated repeatable in-vivo recordings of compound action potentials from the rat sciatic nerve. Our results show that this electrode is suitable for repeated in-vivo recordings of compound action potentials from nerves in applications such as peripheral and visceral nerve interfaces that require low-noise stable nerve recordings.
{"title":"An intrafascicular electrode with integrated amplifiers for peripheral nerve recording","authors":"K. Ng, A. Cutrone, S. Bossi, S. Nag, Ignacio Delgado-Martínez, Swathi Sheshadri, Claire A. Poulard, Y. Xu, S. Yen, N. Thakor","doi":"10.1109/NER.2015.7146642","DOIUrl":"https://doi.org/10.1109/NER.2015.7146642","url":null,"abstract":"Thin-film longitudinal intrafascicular electrodes (tf-LIFE) are widely used for peripheral nerve recordings. tf-LIFEs are also promising electrodes for neural signal acquisition in future peripheral nerve prostheses. However, common mode signal interference, and electrical artifacts originating from long wire leads and wire movement are known problems encountered when using such electrodes, which lead to degradation in the recording quality. Here, we report an active tf-LIFE electrode implemented by integrating a neural amplifier chip die in close proximity to a tf-LIFE electrode. Consuming only 1mW and measuring 37 mm×7.2 mm×2.4 mm, this active tf-LIFE electrode creates a reliable connection and considerably shortens the distance between the electrode site and neural amplifier. This active electrode has demonstrated repeatable in-vivo recordings of compound action potentials from the rat sciatic nerve. Our results show that this electrode is suitable for repeated in-vivo recordings of compound action potentials from nerves in applications such as peripheral and visceral nerve interfaces that require low-noise stable nerve recordings.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132540803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146662
P. Troyk, Samuel D. Bredeson, S. Cogan, M. Romero-Ortega, Sungjae Suh, Zhe Hu, A. Kanneganti, Rafael Granja-Vazquez, J. Seifert, M. Bak
Wireless stimulation of neural tissue could enable many emerging neural prosthesis designs, and eliminate problems associated with percutaneous wires and connectors. Our laboratory has developed a 16-channel wireless floating microelectrode array (WFMA) for chronic implantation. Here, we report on its first use within in-vivo experiments, using a rat sciatic nerve model. Stimulus currents and associated muscular movements were determined for electrodes of two WFMA devices implanted into four animal subjects.
{"title":"In-vivo tests of a 16-channel implantable wireless neural stimulator","authors":"P. Troyk, Samuel D. Bredeson, S. Cogan, M. Romero-Ortega, Sungjae Suh, Zhe Hu, A. Kanneganti, Rafael Granja-Vazquez, J. Seifert, M. Bak","doi":"10.1109/NER.2015.7146662","DOIUrl":"https://doi.org/10.1109/NER.2015.7146662","url":null,"abstract":"Wireless stimulation of neural tissue could enable many emerging neural prosthesis designs, and eliminate problems associated with percutaneous wires and connectors. Our laboratory has developed a 16-channel wireless floating microelectrode array (WFMA) for chronic implantation. Here, we report on its first use within in-vivo experiments, using a rat sciatic nerve model. Stimulus currents and associated muscular movements were determined for electrodes of two WFMA devices implanted into four animal subjects.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"48 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130161764","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146652
Hirokazu Takahashi, T. I. Shiramatsu, Kazusa Takahashi, T. Noda, R. Kanzaki, H. Nakahara
Simultaneous characterization of layer-specific activation in the cortex and topographically organized activation in the thalamus brings substantial benefits to advance the understanding of the sensory/motor functions. We designed a silicon-probe microelectrode array to simultaneously characterize the primary auditory cortex (A1) and thalamus (medial geniculate body; MGB), which are aligned in the dosro-lateral to ventro-medial axis perpendicular to the cortical surface of A1. The array had 3 shanks with 6-mm length. On each shank, 15 recording sites were made at the tip for MGB and 17 sites were made at the bottom for A1. A laser displacement meter was proved useful to make appropriate insertion of the array probe at a right angle with respect to the cortical surface. Our experiments in vivo demonstrated the capability of the designed array to investigate the thalamo-cortical interaction between tonotopically organized activities in the thalamus and layer-specific activities in the cortex.
{"title":"Simultaneous microelectrode recording of layered structure of cortex and tonotopic structure of thalamus in the auditory pathway","authors":"Hirokazu Takahashi, T. I. Shiramatsu, Kazusa Takahashi, T. Noda, R. Kanzaki, H. Nakahara","doi":"10.1109/NER.2015.7146652","DOIUrl":"https://doi.org/10.1109/NER.2015.7146652","url":null,"abstract":"Simultaneous characterization of layer-specific activation in the cortex and topographically organized activation in the thalamus brings substantial benefits to advance the understanding of the sensory/motor functions. We designed a silicon-probe microelectrode array to simultaneously characterize the primary auditory cortex (A1) and thalamus (medial geniculate body; MGB), which are aligned in the dosro-lateral to ventro-medial axis perpendicular to the cortical surface of A1. The array had 3 shanks with 6-mm length. On each shank, 15 recording sites were made at the tip for MGB and 17 sites were made at the bottom for A1. A laser displacement meter was proved useful to make appropriate insertion of the array probe at a right angle with respect to the cortical surface. Our experiments in vivo demonstrated the capability of the designed array to investigate the thalamo-cortical interaction between tonotopically organized activities in the thalamus and layer-specific activities in the cortex.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"112 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134410698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146608
M. Im, S. Fried
Retinal prosthetics consistently demonstrate the ability to restore limited visual perception to those blinded from outer retinal degenerative diseases. However, the performance of retinal implants is highly inconsistent and high-density arrays have proven only marginally better than much sparser ones suggesting that improving the overall quality of elicited vision may require more than just a high density electrode array. Existing devices are also implanted subretinally and epiretinally raising the possibility that electrode location also contributes to percept quality. Here, we compared the responses to stimulation from subretinal and epiretinal electrodes in the same cell. Use of a 4×4 subretinal electrode array allowed us to also compare responses to different numbers of electrodes activated simultaneously. Surprisingly, responses showed minimal dependence of both the electrode position (epiretinal vs. subretinal) as well as on electrode size (one vs. up to nine electrodes). However, when charge density considerations are implemented, such as those that are necessary during clinical use, the responses arising from smaller electrodes were less effective. This finding may help to explain the inconsistency between theoretical visual acuity and achievement in clinical testing with the high density implanted arrays.
{"title":"Spatial properties of network-mediated response of retinal ganglion cells to electric stimulation","authors":"M. Im, S. Fried","doi":"10.1109/NER.2015.7146608","DOIUrl":"https://doi.org/10.1109/NER.2015.7146608","url":null,"abstract":"Retinal prosthetics consistently demonstrate the ability to restore limited visual perception to those blinded from outer retinal degenerative diseases. However, the performance of retinal implants is highly inconsistent and high-density arrays have proven only marginally better than much sparser ones suggesting that improving the overall quality of elicited vision may require more than just a high density electrode array. Existing devices are also implanted subretinally and epiretinally raising the possibility that electrode location also contributes to percept quality. Here, we compared the responses to stimulation from subretinal and epiretinal electrodes in the same cell. Use of a 4×4 subretinal electrode array allowed us to also compare responses to different numbers of electrodes activated simultaneously. Surprisingly, responses showed minimal dependence of both the electrode position (epiretinal vs. subretinal) as well as on electrode size (one vs. up to nine electrodes). However, when charge density considerations are implemented, such as those that are necessary during clinical use, the responses arising from smaller electrodes were less effective. This finding may help to explain the inconsistency between theoretical visual acuity and achievement in clinical testing with the high density implanted arrays.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132866834","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146628
G. Newman, M. Fifer, H. Benz, N. Crone, N. Thakor
Connectivity measures provide a quantification of information flow across electrodes in human subject electrocorticography (ECoG). They do not, however, lend themselves to direct interpretation due to the combinatorial size increase of the feature space. We utilize time-varying dynamic Bayesian networks (TV-DBN) as a model of the individual ECoG electrode activity based on the activation of the electrode array. Using the high gamma power TV-DBN connectivity matrices, we determine if eigenvector centrality can objectively highlight the important interactions between electrodes. The statistically thresholded centrality measure reveals task-related differences in the significant electrode subsets during distinct task phases (p<;0.05; 13 significant electrodes overall: 2 exclusive to the cue processing phase, 3 exclusive to the motor output phase). These results suggest that TV-DBN and centrality analysis can be used in an online brain-mapping system to show regions of the brain relevant to real-time task performance.
{"title":"Eigenvector centrality reveals the time course of task-specific electrode connectivity in human ECoG","authors":"G. Newman, M. Fifer, H. Benz, N. Crone, N. Thakor","doi":"10.1109/NER.2015.7146628","DOIUrl":"https://doi.org/10.1109/NER.2015.7146628","url":null,"abstract":"Connectivity measures provide a quantification of information flow across electrodes in human subject electrocorticography (ECoG). They do not, however, lend themselves to direct interpretation due to the combinatorial size increase of the feature space. We utilize time-varying dynamic Bayesian networks (TV-DBN) as a model of the individual ECoG electrode activity based on the activation of the electrode array. Using the high gamma power TV-DBN connectivity matrices, we determine if eigenvector centrality can objectively highlight the important interactions between electrodes. The statistically thresholded centrality measure reveals task-related differences in the significant electrode subsets during distinct task phases (p<;0.05; 13 significant electrodes overall: 2 exclusive to the cue processing phase, 3 exclusive to the motor output phase). These results suggest that TV-DBN and centrality analysis can be used in an online brain-mapping system to show regions of the brain relevant to real-time task performance.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114826505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2015-04-22DOI: 10.1109/NER.2015.7146744
K. Adhikari, S. Tatinati, K. Veluvolu, K. Nazarpour
Physiological tremor is an involuntary and rhythmic movement of the body specially the hands. The vibrations in hand-held surgical instruments caused by physiological tremor can cause unacceptable imprecision in microsurgery. To rectify this problem, many adaptive filtering-based methods have been developed to model the tremor to remove it from the tip of microsurgery devices. The existing tremor modeling algorithms such as the weighted Fourier Linear Combiner (wFLC) algorithm and its extensions operate on the x, y, and z dimensions of the tremor signals independently. These algorithms are blind to the dynamic couplings between the three dimensions. We hypothesized that a system that takes these coupling information into account can model the tremor with more accuracy compared to the existing methods. Tremor data was recorded from five novice subjects and modeled with a novel quaternion weighted Fourier Linear Combiner (QwFLC). We compared the modeling performance of the proposed QwFLC with that of the conventional wFLC algorithm. Results showed that QwFLC improves the modeling performance by about 20% at the cost of higher computational complexity.
{"title":"Modeling 3D tremor signals with a quaternion weighted Fourier Linear Combiner","authors":"K. Adhikari, S. Tatinati, K. Veluvolu, K. Nazarpour","doi":"10.1109/NER.2015.7146744","DOIUrl":"https://doi.org/10.1109/NER.2015.7146744","url":null,"abstract":"Physiological tremor is an involuntary and rhythmic movement of the body specially the hands. The vibrations in hand-held surgical instruments caused by physiological tremor can cause unacceptable imprecision in microsurgery. To rectify this problem, many adaptive filtering-based methods have been developed to model the tremor to remove it from the tip of microsurgery devices. The existing tremor modeling algorithms such as the weighted Fourier Linear Combiner (wFLC) algorithm and its extensions operate on the x, y, and z dimensions of the tremor signals independently. These algorithms are blind to the dynamic couplings between the three dimensions. We hypothesized that a system that takes these coupling information into account can model the tremor with more accuracy compared to the existing methods. Tremor data was recorded from five novice subjects and modeled with a novel quaternion weighted Fourier Linear Combiner (QwFLC). We compared the modeling performance of the proposed QwFLC with that of the conventional wFLC algorithm. Results showed that QwFLC improves the modeling performance by about 20% at the cost of higher computational complexity.","PeriodicalId":137451,"journal":{"name":"2015 7th International IEEE/EMBS Conference on Neural Engineering (NER)","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121940818","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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