Brain electricaL activity mapping
First Claim
1. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprisinga plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient,stimulus means for repeatedly providing a sensory stimulus for activating the brain to produce EP responses to said transducers,response averaging means connected to be responsive to said transducers, to produce average responses for each transducer,processing means connected to be responsive to said averaging means for processing said average responses to generate a time sequence of matrices,display means connected to be responsive to said processing means, for displaying said matrices as a time sequence of topographic maps of the skull, said matrice having elements defining discrete points of said maps,said display means including means for displaying said topographic maps at a variable frame rate, said maps corresponding to different portions of said average responses being displayed respectively at different selected frame rates.
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Accused Products
Abstract
Topographic displays of brain electrical activity are produced from matrices of data derived from evoked potential (EP) and steady-state responses of skull transducers. In different aspects, EP responses are displayed at a variable frame rate, the rate of data sampling is sufficient to capture rapid transient events, difference matrices are derived as the difference between matrices corresponding to two different brain conditions, the baseline of the EP responses is zeroed based on the average prestimulus response, and the steady-state response is analyzed by Fourier transforms. In other aspects, statistical comparison matrices representing statistical differences between corresponding elements in two matrices are generated, a coefficient-of-variance matrix is generated, additional display matrices are temporally interpolated, response waveforms are previewed and tagged for elimination from further processing, the topographic maps are displayed on a video monitor with appropriate scaling of the data to the tones of the display, and additional display points are interpolated between the measured data points for display.
116 Citations
82 Claims
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1. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, stimulus means for repeatedly providing a sensory stimulus for activating the brain to produce EP responses to said transducers, response averaging means connected to be responsive to said transducers, to produce average responses for each transducer, processing means connected to be responsive to said averaging means for processing said average responses to generate a time sequence of matrices, display means connected to be responsive to said processing means, for displaying said matrices as a time sequence of topographic maps of the skull, said matrice having elements defining discrete points of said maps, said display means including means for displaying said topographic maps at a variable frame rate, said maps corresponding to different portions of said average responses being displayed respectively at different selected frame rates.
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4. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus including
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull, processing means connected to be responsive to said transducers, for processing responses of said transducers to generate a time sequence of matrices, each of said matrices having elements representing the instantaneous amplitudes of said responses at various locations on the skull and there being a sufficient number of said matrices for a selected time period of actual brain activity for capturing onset of a transient event that occurs with a rapidity on the order of that of an epileptic spike, said processing means including means to generate from said time sequence of matrices a running-average matrix which at any given time represents the current matrix averaged with a selected number of the matrices preceding it in time, display means connected to be responsive to said processing means, for displaying said matrices as a time sequence of topographic maps of the skull, said elements defining discrete points of said matrice having maps, said display means including means for displaying said topographic maps at a variable frame rate and for selectably slowing said frame rate to permit observation of said transient event.
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6. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, storage means connected to be responsive to said transducers for storing responses of said transducers during first and second time periods, processing means connected to be responsive to said transducers, for processing said responses to generate first and second matrices each having elements representing brain activity at different skull locations, said first matrix representing information on brain activity during said first period, and said second matrix representing information on brain activity during said second period, different means connected to be responsive to said processing means, for forming a difference matrix having elements each corresponding to the difference between corresponding elements of said first and second matrices, display means connected to be responsive to said different means, for displaying said different matrix as a topographic map of the skull, said matrix elements each forming a discrete point of said topographic map.
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8. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, stimulus means for repeatedly generating a sensory stimulus for the brain, to produce at said transducers repeated segments of data, each said segment having a pre-stimulus response and a post-stimulus response, response averaging means connected to be responsive to said transducers, for averaging said segments to produce average pre-stimulus and average post-stimulus responses for each transducer, baseline means connected to be responsive to said responsive averaging means, for determining a zero baseline for said average segments from the mean level of at least a portion of the respective average pre-stimulus response, and subtraction means connected to be responsive to said baseline means, for generating zeroed average segments by subtracting from each average segment the zero baseline determined by said baseline means, processing means connected to be responsive to said subtraction means, for processing said zeroed average segments to generate one or more matrices, each said matrix having element representing information on the electrical activity of the brain at one location on the skull, display means connected to be responsive to said processing means, for displaying said one or more matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps.
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22. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient or measure the EEG response at said locations, sampling means connected to be responsive to said transducers, for sampling said EEG responses during time intervals shorter than the anticipated interval between interruptions in the state of brain activity, spectral processing means connected to be responsive to said sampling means, for computing, for each of said transducers, the Fourier transforms of the sampled EEG responses and for computing from said Fourier transforms, for each of said transducers, the spectral energy contained in selected frequency bands, processing means connected to be responsive to said spectral processing means, for processing the output of said spectral processing means to generate a plurality of matrices, one said matrix for each selected frequency band, each said matrix having elements each of which represents the spectral energy within the respective frequency band at one location on the skull, display means connected to be responsive to said processing means, for displaying said matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps.
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36. Apparatus for generating a topographic display of information of the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, processing means connected to be responsive to said transducers, for processing electrical responses measured at said transducers, said processing means including means for generating one or more matrices, each matrix containing a plurality of elements, said elements representing information on the electrical activity of the brain at particular skull locations, statistical processing means connected to be responsive to said processing means, for processing at least two said matrices to generate a statistical comparison matrix having elements, each element being representative of a statistical difference between the corresponding elements in said two matrices, display means connected to be responsive to said statistical processing means, for displaying said statistical comparison matrix as a topographic map of the skull, said matrix element forming discrete points of said map.
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45. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, statistical processing means connected to be responsive to said transducers, for processing responses at said electrical-activity transducers to generate a coefficient-of-variance matrix, said matri having element each of which represents the normalized standard deviation of the responses at one skull location, the normalized standard deviation being the standard deviation divided by the mean, display means connected to be responsive to said statistical processing means, for displaying said coefficient-of-variance matrix as a topographic map of the skull, thereby providing a map of the level of variation in brain activity.
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46. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, processing means connected to be responsive to said transducers, for generating from responses measured at said transducers a time sequence of first matrices, each said first matrices having display elements representing the instantaneous response at various locations on said skull, temporal interpolation means connected to be responsive to said processing means, for generating by interpolation second matrices interspersed in said sequence of first matrices, said second matrices having elements representing the approximate response at instants of time intermediate the instants of time associated with said first matrices, display means connected to be responsive to said processing means, for displaying said first matrices and said interspersed second matrices as a time sequence of topographic maps of the skull, said matrix elements forming discrete points of said maps, said second matrices enhancing the visual smoothness of the transitions over time between said first matrices.
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47. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, processing means connected to be responsive to said transducers, for generating one or more matrices from the responses measured at said transducers, each matrix having elements representing information on electrical activity of the brain at one location on the skull, display means connected to be responsive to said processing means, for displaying said matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps, waveform quality control means for previewing said transducer responses or processed versions thereof, said quality control means including at least two of the following means means for tagging a response with information on its waveform quality, including an indication of whether the response should be used in later processing, means at the discretion of the operator for eliminating a response from further processing, means for automatically eliminating a response from further processing if a portion thereof exceeds a predetermined threshold, means for smoothing a response to eliminate undesired high frequency components, means for adjusting a zero baseline of a response, said zero baseline having been previously set automatically, means for eliminating selected portions of a response from further processing, and means for displaying in numerical form the value of a response at a point in time selected by the operator.
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48. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, means connected to be responsive to said transducers, for sampling responses measured at said transducers and storing the sampled responses as a series of data matrices, one matrix for each sampling time, means connected to be responsive to said means for sampling, for selectively viewing the sampled responses corresponding to a single transducer as a plot of transducer output versus time, quality control means for adjusting portions of said selectively viewed responses or eliminating said responses from further processing, processing means connected to be responsive to said means for sampling, for processing said data matrices to generate one or more processed matrices, said processed matrices having elements each corresponding to one transducer location, interpolation means connected to be responsive to said processing means, for generating expanded matrices by expanding the number of elements in said processed matrices to provide elements corresponding to skull locations intermediate said transducer locations, display means connected to be responsive to said interpolation means, including a video monitor capable of generating a matrix of grey tones for displaying said expanded matrices as topographic maps of the skull, said expanded matrices having elements defining the grey tones of discrete points on said maps.
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51. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, processing means connected to be responsive to said transducers, for processing responses measured at said transducers to generate one or more matrices, each matrix having elements representing information on brain activity at different skull locations, display means connected to be responsive to said processing means, for displaying said one or more matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps, said display means including a video monitor which generates a visible grey tone at each said discrete point, said tone being variable from a maximum tone to a minimum tone, and scaling means connected to be responsive to said processing means, for scaling said matrix elements to the available tones.
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59. Apparatus for generating a topographic display of information on the electrical activity of the brain, said apparatus comprising
a plurality of electrical-activity transducers adapted to be placed at spaced apart locations on the skull of a patient, processing means connected to be responsive to said transducers, for processing responses measured at said transducers to generate one or more matrices, each matrix having elements representing information on brain activity at different skull locations, display means connected to be responsive to said processing means, for displaying said one or more matrices as a topographic map of the skull, said matrix elements forming discrete points of said map, said display means including a video monitor which generates a tone at each said discrete point, said tone varying from a maximum tone to a minimum tone, normalizing means connected to be responsive to said processing means, for normalizing said matrix elements to a selected value, and scaling means connected to be responsive to said processing means, for scaling said matrix elements to the available tones, said scaling means including means for assigning a selected tone to said selected normalization value.
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69. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, storing responses of said transducers during first and second time periods, processing said responses to generate first and second matrices each having elements representing brain activity at different skull locations, said first matrix representing information on brain activity during said first period, and said second matrix representing information on brain activity during said second period, forming a difference matrix having elements each corresponding to the difference between corresponding elements of said first and second matrices, and displaying said difference matrix as a topographic map of the skull, said matrix elements each forming a discrete point of said topographic map.
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71. A method of generating a topographic display of information on the EP response of the brain, said method comprising the steps of:
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placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, repeatedly providing a sensory stimulus for the brain so as to produce at said transducers repeated segments of data, each segment including a pre-stimulus response and a post-stimulus response, averaging the repeated segments to produce an average segment for each transducer, determining a zero baseline for each average segment from the mean level of at least a portion of the average pre-stimulus response, subtracting the zero baselines from the respective average segments to produce zeroed average segments, processing the zeroed average segments to generate one or more matrices of elements, with each matrix element representing information on the EP response at one location on the skull, and displaying said one or more matrices as topographic maps of the skull, with each display point forming a discrete point on said maps.
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72. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, repeatedly providing a sensory stimulus for activating the brain to produce EP responses at said transducers, averaging said responses to produce average responses for each transducer, processing said average responses to generate a time sequence of matrices, displaying said matrices as a time sequence of topographic maps of the skull, said matrices having elements defining discrete points of said maps, and displaying said topographic maps at a variable frame rate, maps corresponding to different portions of said average responses being displayed respectively at different selected frame rates.
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73. A method for generating a topographic display of information on the electrical activity of the brain, said method including the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull, processing responses of said transducers to generate a time sequence of matrices, each said matrix having elements representing the instantaneous amplitudes of said responses at various locations on the skull and there being a sufficient number of said matrices for a selected time period of actual brain activity for capturing onset of a transient event that occurs with a rapidity on the order of that of an epileptic spike, generating from said time sequence of matrices a running-average matrix which at any given time represents the current matrix averaged with a selected number of the matrices preceding it in time, displaying said matrices as a time sequence of topographic maps of the skull at a variable frame rate, each running-average matrix having elements defining discrete points of said maps, and selectably slowing the frame rate at which said topographic maps are displayed so as to permit observation of said transient event.
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74. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient to measure the EEG response at said locations, sampling the EEG responses during time intervals shorter than the anticipated interval between interruptions in the state of brain activity, computing, for each of said transducers, the Fourier transforms of the sampled EEG responses and computing from said Fourier transforms, for each of said transducers, the spectral energy contained in selected frequency bands, processing said computed spectral energy of said selected frequency bands to generate a plurality of matrices, one said matrix for each selected frequency band, said matrices having elements representing the spectral energy within the respective frequency band at one location on the skull, and displaying said matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps.
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75. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, processing electrical responses measured at said transducers, said processing means including means for generating one or more matrices, each matrix containing a plurality of elements, said elements representing information on the electrical activity of the brain at particular skull locations, processing at least two said matrices to generate a statistical comparison matrix said statistical comparison matrix having elements each of which representative of a statistical difference between the corresponding elements in said two matrices, and displaying said statistical comparison matrix as a topographic map of the skull, said matrix elements forming discrete points of said map.
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76. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, statistically processing responses at said electrical-activity transducers to generate a coefficient-of-variance matrix, said matrix having elements each of which represents the normalized standard deviation of the responses at one skull location, the normalized standard deviation being the standard deviation divided by the mean, displaying said coefficient-of-variance matrix as a topographic map of the skull, thereby providing a map of the level of variation in brain activity.
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77. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers for placement at spaced apart locations on the skull of a patient, generating from responses measured at said transducers a time sequence of first matrices, each said first matrix having display elements representing the instantaneous response at various locations on said skull, generating by interpolation second matrices interspersed in said sequence of first matrices, said second matrices having elements representing the approximate response at instants of time intermediate the instants of time associated with said first matrices, displaying said first matrices and said interspersed second matrices as a time sequence of topographic maps of the skull, said matrix elements forming discrete points of said maps, said second matrices enhancing the visual smoothness of the transitions over time between said first matrices.
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78. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, generating one or more matrices from responses measured at said transducers, each matrix having elements representing information on the electrical activity of the brain at one location on the skull, displaying said one or more matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps, previewing said transducer responses or processed versions thereof, said previewing including at least two of the following steps tagging a response with information on its waveform quality, including an indication of whether the response should be used in later processing, eliminating a response from further processing at the discretion of the operator, automatically eliminating a response from further processing if a portion thereof exceeds a predeterminedthreshold, smoothing a response to eliminate undesired high frequency components, adjusting a zero baseline of a response, said zero baseline having been previously set automatically eliminating selected portions of a response from further processing, and displaying in numerical form the value of a response at a point in time selected by the operator.
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79. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, sampling responses measured at said transducers and storing the sampled data as a series of data matrices, one matrix for each sampling time, selectively viewing the sampled data corresponding to a single transducer as a plot of transducer output versus time, adjusting portions of said selectively viewed data or eliminating said data from further processing, processing said data matrices to generate one or more processed matrices said one or more processed matrices having elements each corresponding to one transducer location, expanding the number of elements in said one or more processed matrices to provide elements corresponding to skull locations intermediate said transducer locations, providing a video monitor capable of generating a matrix of grey tones for displaying said expanded matrices as topographic maps of the skull, said expanded matrix elements defining the grey tones of discrete points on said maps.
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80. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, processing responses measured at said transducers to generate one or more matrices, each matrix having elements representing information on brain activity at different skull locations, displaying one or more said matrices as topographic maps of the skull, said matrix elements forming discrete points of said maps, providing a video monitor which generates a visible grey tone at each said discrete point, said tone being variable from a maximum tone to a minimum tone, and scaling said matrix elements to the available tones.
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82. A method for generating a topographic display of information on the electrical activity of the brain, said method comprising the steps of
placing a plurality of electrical-activity transducers at spaced apart locations on the skull of a patient, processing responses measured at said transducers to generate one or more matrices, each matrix having elements representing information on brain activity at different skull locations, displaying said one or more matrices as a topographic map of the skull, said matrix elements forming discrete points of said map, providing a video monitor which generates a tone at each said discrete point, said tone varying from a maximum tone to a minimum tone, normalizing said matrix elements to a selected value, and scaling said matrix elements to the available tones, said scaling means including means for assigning a selected tone to said selected normalization value.
Specification