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ABSTRACT: This paper proposes an implementation of automatic classification of respiratory signals using a field programmable gate array (FPGA). It has been shown for this type of respiratory signal that second order autoregressive modeling (AR) combined with a modified zero-crossing algorithm results in close to 100% consistency between manual and automatic classification methods. This algorithm was improved by adding calibration procedures and adjusted to run on an FPGA. Altera's development tools and intellectual property (IP) mega-core functions were utilized to implement a "soft-core" processor capable of running compiled C algorithms inside the Stratii FPGA chip. In addition, the high density and flexibility of the FPGA allowed for coupling of the soft-core processor with other hardware modules to form a fast interface between off-chip devices. The external SRAM, flash memory, and an LCD were interfaced with the NIOS II soft-core processor through a system on a programmable chip (SOPC) design.
Bioengineering Conference, 2005. Proceedings of the IEEE 31st Annual Northeast; 05/2005
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ABSTRACT: The purpose of this study was to examine the interrelationship between hippocampal sub fields CA1 and dentate gyrus using magnitude square coherence analysis of freely moving rats during REM sleep. Our preliminary results from 90-day old animals showed strong coherence between CA1 and dentate gyrus at 7 Hz. This finding agrees with previously published work, and provides us with an appropriate measure of these interrelationships in infant rats during the pre-weaning stage of development.
Bioengineering Conference, 2003 IEEE 29th Annual, Proceedings of; 04/2003
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ABSTRACT: A real-time biomedical signal analysis system based on SHARC
ADSP-21062 EZ-LAB board was examined in this paper. Installed as an
embedded system on a PC workstation, the DSP board was tested for
real-time performance in extracting features from respiration signals
and classification among different respiration episodes, including
apnea. Test results show that high performance DSP boards may be easily
setup in a typical biomedical laboratory to perform and to be used
effectively in heavy computation for a real-time application
Bioengineering Conference, 2002. Proceedings of the IEEE 28th Annual Northeast; 02/2002
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ABSTRACT: This paper presents a cross-bispectral analysis of the ontogeny of
the hippocampal EEG recorded from the dentate gyrus and CA1. The effects
of nonlinear quadratic phase coupling between hippocampal EEG at CA1 and
the dentate gyrus was examined using the cross-bicoherence index.
Results of cross-bispectral analysis of the hippocampal EEG during REM
sleep shows the shift to higher θ frequency as animals mature
from 15 to 90 days of age
Bioengineering Conference, 2002. Proceedings of the IEEE 28th Annual Northeast; 02/2002
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T. Ning
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ABSTRACT: A multi-channel autoregressive (MAR) modeling algorithm is introduced. The new method treats MAR modeling as a vector orthogonal projection, where the optimal MAR coefficient matrices lead to prediction error vectors whose linear dependency upon available measurement vectors is minimized. The standard Gram-Schmidt orthogonal transform was extended to multi-channel time series and utilized to calculate the MAR coefficient matrices. Simulation results show that multi-channel power spectra thus derived from the orthogonal projection method exhibit good frequency resolution, without line splitting and frequency bias, and the coherence was also accurately estimated
Signal Processing Proceedings, 2000. WCCC-ICSP 2000. 5th International Conference on; 02/2000
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ABSTRACT: This paper presents the bispectral analysis of the ontogeny of the hippocampal EEG recorded from the dentate gyrus and CA1, the primary sites that generate theta (theta) rhythm. The hippocampal EEG was collected during the vigilance state of rapid eye movement (REM) sleep of freely moving rats at 15, 30 and 90 days of age. In previous studies we demonstrated through bispectral analysis that significant quadratic phase coupling (QPC) of the EEG exists in the hippocampal formation of CA1 and the dentate gyrus during REM sleep, primarily in the theta (4-11 Hz) frequency range. In the present study we have examined whether QPC can be used as an effective measure of development, i.e., maturation of the hippocampal subfields CA1 and the dentate gyrus. We found that as animals mature from the age of 15 to 90 days, the occurrence of nonlinear QPC activities moves from (6.25 Hz, 6 Hz) to (7 Hz, 7 Hz) at CA1 and (6 Hz, 6 Hz) to (7.5 Hz, 7.5 Hz) at the dentate gyrus, respectively. The results indicate that bispectral analysis provides an additional and important description of the frequency characteristics of the hippocampal EEG and that the QPC measure is also a useful index to quantify the shift in the hippocampal theta frequency as animals mature.
Annals of Biomedical Engineering 06/1998; 26(4):688-93. · 2.37 Impact Factor
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ABSTRACT: One of the major goals of the authors' laboratory has been the
development of a specific measure of neuronal brain development that can
be used to evaluate the impact of insults to the brain. Here, they
report on preliminary studies of using the bicoherence index as a
measure of the developing neuronal interactions that take place between
hippocampal subfields CA1 and the dentate gyrus-the primary generators
of hippocampal theta rhythm
Engineering in Medicine and Biology Society, 1995., IEEE 17th Annual Conference; 10/1995
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ABSTRACT: The paper discusses the use of nonlinear bispectral analysis in examining the hippocampal EEG collected at subfields of CA1 and the dentate gyrus during the vigilance state of REM sleep. The cross-bispectrum and its unique capabilities of detecting and quantifying quadratic nonlinear interactions occurring between these two hippocampal subfields are explained and demonstrated with simulation examples and EEG data. It was found in this study that quadratic nonlinear interactions exist between CA1 and the dentate gyrus in the 6-8 frequency band which dominates the theta (theta) rhythm observed in the hippocampal EEG during REM sleep. As a result, energy components around the frequency band of the second-order harmonics of theta rhythm are not totally spontaneous, but generated largely due to quadratic nonlinear interactions.
IEEE Transactions on Biomedical Engineering 10/1993; 40(9):870-6. · 2.28 Impact Factor
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ABSTRACT: The two sidebands generated around the carrier frequency by amplitude modulation (AM) can be treated as the result of quadratic phase coupling (QPC) between the frequency of the information bearing signal and the frequency of the carrier. Although the bispectrum is useful for detecting QPC, it will generate ambiguity. To avoid the ambiguity observed in the bispectrum, a simple fix of the existing bispectrum estimator, which allows the detection of amplitude modulation and distinguishes spontaneous frequencies from those due to nonlinear coupling, is proposed. A simulation example is provided to illustrate the effectiveness of the approach, followed by discussion of its possible use
Acoustics, Speech, and Signal Processing, 1992. ICASSP-92., 1992 IEEE International Conference on; 04/1992
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ABSTRACT: Three algorithms are developed to reproduce uniformly spaced
correlation measurements for power spectrum estimation. Some general
relations between the randomly spaced correlation samples and the power
spectrum are derived. The details of the three algorithms that can be
used to reproduce uniformly spaced correlation measurements are
included. Simulation examples using sinusoidal signals are given to
examine the adverse effects due to the correlation randomness as well as
to demonstrate improvements achieved by the suggested algorithms
IEEE Transactions on Acoustics Speech and Signal Processing 07/1990;
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ABSTRACT: A spike separation system utilizing the waveform descriptors, activity (power) and mobility (slope spread), originally described by B. Hjorth (1970) is presented. Comparisons are made with the reduced feature matching technique of peak-to-peak amplitude and duration in order to illustrate the versatility of the activity and mobility measures. The effects of varying sample sizes used to capture individual spikes from a multiunit record are discussed. The results demonstrate that activity and mobility are useful measures and appropriate for online, real-time separation of spikelike bioelectric events
Bioengineering Conference, 1990., Proceedings of the 1990 Sixteenth Annual Northeast; 04/1990
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ABSTRACT: Some basic properties of autoregressive (AR) modeling and bispectral analysis are reviewed, and examples of their application in electroencephalography (EEG) research are provided. A second-order AR model was used to score cortical EEGs in order. In tests performed on five adult rats to distinguish between different vigilance states such a quiet-waking (QW), rapid-eye-movement (REM), and slow-wave sleep (SWS), SWS activity was correctly identified over 96% of the time, and a 95% agreement rate was achieved in recognizing the REM sleep stage. In a bispectral analysis of the rat EEG, third-order cumulant (TOC) sequences of 32 epochs belonging to the same vigilance state were estimated and then averaged. Preliminary results have shown that bispectra of hippocampal EEGs during REM Sleep exhibit significant quadratic phase couplings between frequencies in the 6-8-Hz range, associated with the theta rhythm.
IEEE Engineering in Medicine and Biology Magazine 02/1990; 9(1):47-50. · 2.06 Impact Factor
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ABSTRACT: The authors present an automatic classification algorithm which is
used to classify respiratory signals into the following categories: (1)
normal respiration, (2) respiration with artifacts, and (3) apnea. When
the recorded signal is scored as respiration, respiration rate estimates
are computed. Results obtained using pilot data show good agreement with
the classifications obtained by manual scoring methods
Engineering in Medicine and Biology Society, 1989. Images of the Twenty-First Century., Proceedings of the Annual International Conference of the IEEE Engineering in; 12/1989
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ABSTRACT: Bispectra were computed to detect phase coupling in the cortical and hippocampal EEG of the rat during various vigilance states. For EEGs recorded from the hippocampus, significant phase coupling was obtained during rapid-eye-movement sleep between the frequency components (6-8 Hz) associated with theta rhythm. The results indicate that the bispectral analysis of the EEG can reveal extra information not obtainable from the power spectrum and may provide insight regarding the formation of the EEG within different brain structures during various vigilance states.
IEEE Transactions on Biomedical Engineering 05/1989; · 2.28 Impact Factor
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ABSTRACT: The coherence functions between EEGs (electroencephalograms)
collected from the hippocampal subfield CA1 and dentate is reexamined by
conventional (periodogram) and autoregressive (AR) approaches to study
the effects of different data lengths on the performance of these
approaches and the variation of the resultant magnitude squared
coherence (MSC) and phase coherence estimates. The MSC and phase
coherence obtained from the autoregressive method are smoother and
demonstrate lower standard deviation than the results obtained by the
classical approach. In general, the standard deviation of the MSC and
the phase coherence decreases as data length increases, and the standard
deviation of the AR method is less than that of the periodogram. The
results indicate that for applications in which computational speed is
not critical, the multichannel autoregressive model provides a coherence
estimate that is smoother and exhibits lower standard deviation than the
conventional periodogram approach
Bioengineering Conference, 1989., Proceedings of the 1989 Fifteenth Annual Northeast; 04/1989
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ABSTRACT: The multichannel autoregressive model and the periodogram approach
are used to determine coherence and phase measures between the
electrical activity in two distinct brain structures of the rat namely,
the subfields CA1 and dentate gyrus in the hippocampal formation, during
the vigilance states of quiet waking (QW), slow-wave sleep (SWS), and
rapid-eye-movement (REM) sleep. Using both periodogram and multichannel
autoregressive modeling techniques, high coherence and consistent phase
differences were found to exist within the theta range of frequencies
(4-11 Hz) only during REM sleep
Bioengineering Conference, 1988., Proceedings of the 1988 Fourteenth Annual Northeast; 04/1988
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ABSTRACT: Bispectral analyses were utilized to study the rat
electroencephalogram (EEG) to extract information regarding phase
coupling. The results indicate that the EEG recorded from the
hippocampus exhibits a strong phase coupling between frequencies in the
theta band (6-8 Hz) primarily during REM sleep, while the cortical EEG
exhibits a weak coupling between flow frequencies in the delta band (0-3
Hz) during quiet-waking. The degree of phase coupling was further
quantified using the biocoherence function. This study provides data not
available from traditional power-spectral analysis
Bioengineering Conference, 1988., Proceedings of the 1988 Fourteenth Annual Northeast; 04/1988
