Brain function monitoring and display system
Inventors
Liley, David Tibor Julian • Delacretaz, Louis Jacques
Assignees
Interested in licensing this patent?
MTEC can help explore whether this patent might be available for licensing for your application.
Publication Number
US-8175696-B2
Publication Date
2012-05-08
Expiration Date
Abstract
A process for analysing an electroencephalogram signal representative of activity of a brain, including: i) generating coefficient data for a signal representation of a portion of the signal; ii) generating pole data representing positions of one or more poles on a complex plane, the positions being generated based on the coefficient data; and iii) generating, based on a mean position of the poles, brain state data representing functional state of the brain.
Core Innovation
An activity display method for a brain obtains an electroencephalogram (EEG) signal and segments the EEG signal into either contiguous or overlapping segments comprised of a sequential number of samples. Each segment is represented as a fixed order autoregressive moving average (ARMA) signal representation with an autoregressive order between 8 and 13 and a moving average order between 5 and 11, and the fixed order ARMA signal representation is rewritten in z-domain notation to obtain a z-domain representation.
For each EEG segment, AR coefficient data and MA coefficient data are generated for the fixed order ARMA signal representation, and poles of the z-domain representation are determined for the segment by substituting the coefficient data into the z-domain representation. A sum of the poles is determined either as the sum of the number of poles determined or as the first autoregressive AR coefficient of the coefficient data, and a mean pole location is determined by dividing the sum of the poles by the number of poles.
An index value representing the activity of the brain is determined by applying a discriminating function to either the sum of the poles or the mean pole location. The index value is displayed on display means, and display refinements include presenting the index value in graphical form and using different colors mapped to predetermined value ranges.
Claims Coverage
The independent claims are clm-00001 and clm-00011. They share a common inventive approach consisting of segmenting EEG, representing each segment with a fixed-order ARMA model with constrained orders, converting to z-domain notation, computing poles and a mean pole location from AR/MA coefficients, applying a discriminating function to pole-derived quantities to obtain a brain activity index, and displaying the index.
Segmented EEG to fixed-order ARMA with constrained orders
Segmenting an electroencephalogram (EEG) signal into either contiguous or overlapping segments comprised of a sequential number of samples and representing the EEG segments as a fixed order autoregressive moving average (ARMA) signal representation with an autoregressive order between 8 and 13 and a moving average order between 5 and 11.
ARMA rewritten into z-domain notation
Rewriting the fixed order ARMA signal representation in z-domain notation to obtain a z-domain representation for said segments of said EEG signal.
Pole determination from z-domain representation using coefficients
Generating AR coefficient data and MA coefficient data for said segments for said fixed order ARMA signal representation and determining the poles of said z-domain representation for said segments by substituting said coefficient data for said segments of said EEG signal into said z-domain representation.
Mean pole location from sum of poles
Determining the sum of said poles for said segments either as the sum of the number of poles determined or as the first autoregressive AR coefficient of said coefficient data, and determining the mean pole location for said segments by dividing the sum of said poles by the number of said poles.
Discriminating function to compute activity index from poles
Determining an index value representing the activity of the brain for said segments by applying a discriminating function to either the sum of the poles or the mean pole location for said segments.
Displaying the brain activity index
Displaying said index value on display means, with the system claim further having display means for displaying said index value.
Across the independent claims, brain activity is computed from segmented EEG by fitting a fixed-order ARMA representation with constrained autoregressive and moving average orders, converting the representation into z-domain notation, computing poles and mean pole location from AR/MA coefficient data, and applying a discriminating function to pole-derived quantities to produce an index value that is displayed.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
Interested in licensing this patent?