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- Johansson, Rolf, et al.
(author)
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Adaptation of Multi-Joint Movements during Postural Disturbances.
- 2004
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In: Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference. - 1557-170X. - 0780384393 ; 1, s. 149-152
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Conference paper (peer-reviewed)abstract
- The objective was to investigate the adaptation ofthe multi-segmented body movements induced over time byvibratory proprioceptive stimulation of the calf muscles and by galvanic vestibular stimulation. Twelve normal subjects were with eyes open or eyes closed exposed to vibratory stimulation of two different amplitudes and frequencies, or to simultaneously applied galvanic and vibratory stimulation. Multi-input multi-output system identification methods as well as quantitative analysis were applied to the biomechanical experimental data of anteroposterior and lateral body movements and torques induced towards the ground. The immediate adaptive response to the stimulation onset was that the subjects adopted a more rigid posture with coordinated movements of primarily head-shoulder and headhip body segments. The body-movement amplitudes at allmeasured sites as well as the amplitudes of the ground support forces decreased over time as a result of another, somewhat slower adaptation process. The subjects required more time to adapt to a rigid movement pattern when the subjects were simultaneously exposed to both galvanic and vibratorystimulation. Moreover, the accuracy of the MIMO model andcorrelation analysis between measured torque variance andhead; shoulder; hip and knee movement variance suggests thatforce platform recordings reflect both in anteroposterior and lateral direction the body movements at these sites.
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| 2. |
- Löfgren, N., et al.
(author)
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On evaluation of spectrum estimators for EEG
- 2004
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In: Proceedings Of The 26th Annual International Conference Of The IEEE Engineering In Medicine And Biology Society. - : IEEE. - 0780384393 ; 1, s. 305-9
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Conference paper (peer-reviewed)abstract
- In the search for how neonatal EEG is affected by asphyxia it is of importance to find reliable estimates of EEG power spectra. Several spectral estimation methods do exist, but since the true spectra are unknown it is hard to tell how well the estimators perform. Therefore a model to generate simulated EEG with known spectrum is proposed and the model is used to evaluate performance of several parametric and Fourier based spectral estimators.
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| 3. |
- Nissila, I, et al.
(author)
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Auditory hemodynamic studies of newborn infants using near-infrared spectroscopic imaging
- 2004
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In: IEEE Engineering in Medicine and Biology Society. Conference Proceedings. - 1557-170X. ; 2, s. 1244-1274
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Journal article (peer-reviewed)abstract
- The noninvasive study of tissue blood volume and oxygenation using near-infrared light is a new and actively developing technology. We have used near-infrared spectroscopic imaging (NIRSI) to study hemodynamic responses on the auditory cortices evoked by auditory stimulation. Ten healthy newborn infants were studied. The otoacoustic emission hearing test was performed for each infant. Pulse oximetry was used to monitor the heart rate during the measurement, video recording was used to monitor motion artifacts, and the eye movements were noted in order to determine sleep stage. A 16-channel frequency-domain optical imaging system developed in our laboratory was used for NIRSI measurements. The stimuli were presented in trains of seven 1 kHz beeps with 700-ms inter-stimulus intervals. The stimulus trains were separated by 25-s silent periods in order to allow for the hemodynamic delay. In 3/8 cases, we obtained a clear bilateral increase in [HbO/sub 2/], and in two additional cases, a clear response on one hemisphere. The mean change in [HbO/sub 2/] was +0.9+/-0.9muM and the mean change in [Hb] was -0.3+/-0.4muM for those channels producing the largest response for each subject. No statistically significant response was found in 3/8 cases.
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| 5. |
- Seoane, Fernando, 1976-, et al.
(author)
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Brain electrical impedance at various frequencies : the effect of hypoxia
- 2004
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In: Proceedings of the 26th Annual International Conference of the IEEE EMBS, San Francisco, CA, USA • September 1-5, 2004. - : IEEE Engineering in Medicine and Biology Society. - 0780384393 ; 3, s. 2322-5
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Conference paper (peer-reviewed)abstract
- Non-invasive multi-frequency measurements of transcephalic impedance, both reactance and resistance, can efficiently detect cell swelling of brain tissue and can be used for early detection of threatening brain damage. We have performed experiments on piglets to monitor transcephalic impedance during hypoxia. The obtained results have confirmed the hypothesis that changes in the size of cells modify the tissue impedance. During tissue inflammation after induced hypoxia, cerebral tissue exhibits changes in both reactance and resistance. Those changes are remarkably high, up to 71% over the baseline, and easy to measure especially at certain frequencies. A better understanding of the electrical behaviour of cerebral tissue during cell swelling would lead us to develop effective non-invasive clinical tools and methods for early diagnosis of cerebral edema and brain damage prevention.
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