| 1. |
- Blad, Börje
(författare)
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An electrical impedance model for deep brain stimulation of Parkinson's disease
- 2007
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Ingår i: 13th International Conference on Electrical Bioimpedance and the 8th Conference on Electrical Impedance Tomography. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1680-0737. - 9783540738404 ; 17, s. 60-61
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Konferensbidrag (refereegranskat)abstract
- Deep brain stimulation is an accepted technique for the treatment of Parkinson's disease. Deep brain stimulation affects the electrical functions of neurons and several explanations are available to describe this treatment modality. Such as depolarization blockade, synaptic inhibition, synaptic depression and stimulation induced modulation of pathological network activity. An electrical impedance model of the treatment area around the electrodes in the brain is determined to further increase the understanding of deep brain stimulation. This model shows the contact impedance between the electrodes and the tissue, the extra cellular resistance, the intra cellular resistance of the neurons and the effect of deep brain stimulation on the treated area in the brain, which in this case is stimulation of the sub thalamic nucleus. The generated electrical field near the electrodes is high enough to perform an electropermeabilization of the cell membranes. This is modelled as a cell membrane capacitance in series with a resistance. The resistance is the consequence of electropermeabilization of the cell membranes. Many observed parameters that occur during deep brain stimulation is reduced tremor activity, influence on speech, the same effect as a lesion, increased axon activity downstream, followed by durations of nerve silence.
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| 2. |
- Seoane Martinez, Fernando, 1976, et al.
(författare)
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A Novel Approach for Estimation of Electrical Bioimpedance: Total Least Square
- 2007
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Ingår i: International Federation for Medical and Biological Engineering Proceedings. - 1680-0737. ; 17, s. 190-193, s. 190-193
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Konferensbidrag (refereegranskat)abstract
- There are several methods used for AC-impedance estimation in Electrical Bioimpedance measurements. In this paper we propose a novel method for digital estimation of electrical impedance based in the Total Least Square (TLS) technique and we carry out a performance comparison between the proposed method and the typical Digital Sine Correlation (DSC) method. The TLS method has been implemented using the Singular Value Decomposition approach and the performance of both methods have been compared in terms of robustness against noise and size of the data set. The results indicate that the TLS method shows a better performance for impedance estimation than the DSC with reduced set of measurement samples and high SNR levels, while its performance worsen for increasing number of samples and decreasing SNR. The DSC method exhibits a better robustness against noise, especially for increasing the number of data samples. The main observed advantage of the TLS method is that it suffers from less mathematical constrains than the DSC method, and since the noise levels in bioimpedance applications are not expected to be very high we conclude that the TLS method is a good choice as impedance estimator.
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