WO2000056212A1 - Real-time brain wave analysis system and method using fast fourier transform - Google Patents

Real-time brain wave analysis system and method using fast fourier transform Download PDF

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Publication number
WO2000056212A1
WO2000056212A1 PCT/KR2000/000074 KR0000074W WO0056212A1 WO 2000056212 A1 WO2000056212 A1 WO 2000056212A1 KR 0000074 W KR0000074 W KR 0000074W WO 0056212 A1 WO0056212 A1 WO 0056212A1
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WO
WIPO (PCT)
Prior art keywords
brain wave
time
wave data
real
multigraph
Prior art date
Application number
PCT/KR2000/000074
Other languages
French (fr)
Inventor
Pyong Woon Park
Hyeong Seok Kim
Original Assignee
Korea Research Institute Of Jungshin Science
Changse Co., Ltd.
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Publication date
Application filed by Korea Research Institute Of Jungshin Science, Changse Co., Ltd. filed Critical Korea Research Institute Of Jungshin Science
Priority to AU24635/00A priority Critical patent/AU2463500A/en
Publication of WO2000056212A1 publication Critical patent/WO2000056212A1/en

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/72—Signal processing specially adapted for physiological signals or for diagnostic purposes
    • A61B5/7235—Details of waveform analysis
    • A61B5/7253—Details of waveform analysis characterised by using transforms
    • A61B5/7257—Details of waveform analysis characterised by using transforms using Fourier transforms
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/369—Electroencephalography [EEG]
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/24—Detecting, measuring or recording bioelectric or biomagnetic signals of the body or parts thereof
    • A61B5/316—Modalities, i.e. specific diagnostic methods
    • A61B5/369—Electroencephalography [EEG]
    • A61B5/372—Analysis of electroencephalograms
    • A61B5/374—Detecting the frequency distribution of signals, e.g. detecting delta, theta, alpha, beta or gamma waves
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/74—Details of notification to user or communication with user or patient ; user input means
    • A61B5/742—Details of notification to user or communication with user or patient ; user input means using visual displays
    • A61B5/743—Displaying an image simultaneously with additional graphical information, e.g. symbols, charts, function plots

Definitions

  • the present invention relates to a brain wave analysis system and method, and more particularly, to a real-time brain wave analysis system and method for analyzing real-time brain wave data measured by a brain wave measuring device in real time and providing the analyzed brain wave data to a user.
  • a brain wave which is measured at the scalp, is a wave having a potential difference of dozens of micro volts and a frequency of 30 Hz or less.
  • the brain wave is a oh ⁇ sica! value ref!ectin ⁇ a state of human consciousness.
  • the brain wave is divided into an alpha wave, a beta wave, a theta wave and a delta wave.
  • the beta wave has a frequency of at least 13 Hz and is related to usual action in which the five senses are functioning.
  • the alpha wave has a frequency of 8-13 Hz and is related to a relaxed creative state.
  • the theta wave has a frequency of 4-8 Hz and is often detected in adolescents having learning disorder.
  • the delta wave has a frequency of 0.5-4 Hz and typically appears in a normal sleeping state.
  • Brain waves can be read in a time domain or a frequency domain. Reading of brain waves in a time domain requires a lot of experience and skill and it is very difficult to discriminate slight differences.
  • For the method of analyzing the brain wave in the frequency domain it is desired to process a measured signal such that the state of a subject can be easily read in real time.
  • a method for analyzing brain wave data in real time includes the steps of receiving brain wave data and storing it in a memory of a computer, fast Fourier transforming the brain wave data which is stored in the memory of the computer, obtaining mean values of the fast Fourier transformed brain wave in the time and frequency domains, and generating a real-time graph using the time and frequency domain mean values
  • a system for analyzing brain wave data in real time includes a brain wave data receiver for receiving brain wave data which is measured and coded by an external brain wave measu ⁇ nq device a brain wave data transformer for decoding the coded brain wave data which is received by the brain wave data receiver and fast Fourier transforming the decoded brain wave data, a statistic data generator for obtaining time domain mean values and frequency domain mean values with respect to the fast Fourier transformed brain wave data, a multigraph generator for generating a real-time multigraph using the fast Fourier transformed brain wave data, the time domain mean values and the frequency ⁇ omain mean values, ana a muitigraph output for outputting the real-time multigraph to a display screen
  • FIG 1 is a conceptional diagram showing an environment under which a real-time brain wave analysis system according to the present invention is used
  • FIG 2 is a block diagram showing the structure of an embodiment of a brain wave measuring device for measuring brain wave data which is used in a real-time brain wave analysis system according to the present invention
  • FIG 3 is a diagram showing the structure of a headband which is used in the brain wave measuring device
  • FIG 4 is a diagram for explaining a coding procedure performed by the brain wave measuring device
  • FIG 5 is a block diagram showing the hardware structure of a real-time brain wave analysis system according to an embodiment of the present invention
  • FIG 6 is a block diagram showing the functional structure of a real-time brain wave analysis system according to an embodiment of the present invention
  • FIG 7 shows an example of a multigraph which is displayed on a monitor of a real-time brain wave analysis system according to the present invention
  • FIG 8 shows another example of a multigraph which is displayed on a monitor of a real-time brain wave analysis system according to the present invention
  • FIG 9 shows brain wave signals in the time domain, which are generated by a multigraph generator of FIG 6,
  • FIG 10 is a bar graph based in the frequency domain, which is gs ⁇ erateu by a muitigrapi i generator o ⁇ no. o,
  • FIG. 11 is a three-dimensional graph of brain wave amplitude in the time and frequency domains, which is generated by a multigraph generator of FIG 6; and
  • FIG 12 is a two-dimensional graph of brain wave mean values in the frequency domain during a predetermined period of time, which is generated by a multigraph generator of FIG. 6
  • a subject wears a headband 1 to which electrodes are attached, or cup electrodes 2 are attached on the subject's scalp Both the head band 1 and the cup electrodes 2 may be used together
  • An interface 3 which is connected to the electrodes via a cable, then amplifies voltage of dozens of micro volts on the scalp up to voltage of several volts and converts the voltage into digital values
  • a brain wave analysis system 4 encodes the digital values to be readable through a serial port The brain wave analysis system 4 performs a fast Fourier transform on brain wave signals and obtains the strength of the brain wave in each frequency band
  • FIG 2 shows a brain wave measuring device for measuring brain wave data, which is used in a brain wave analysis system according to the present invention
  • the brain wave measuring device includes a brain wave sensor 20, an interface 30 and a serial port connector 40
  • the brain wave sensor 20 senses brain wave signals of four channels at predetermined portions on a subject's scalp using a plurality of electrodes
  • the brain wave sensor 20 includes a headband having two channels and cup electrodes providing two channels
  • the headband having two channels are used to conveniently measure the brain wave at the frontal lobe
  • the cup electrodes providing two channels are used to selectively measure the brain wave at portions other than the frontal lobe, that is, the parietal lobe, the temporal lobe and the occipital lobe
  • the interface 30 is connected to the brain wave sensor 20 via a cable Preferably, a shielded line is used to prevent noise
  • the interface 30 includes an amplifier 31 , an a ⁇ aiog-to-digitai convener 32, a encoder 33 and a computer interface 34
  • the amplifier 31 amplifies the amplitude of weak brain wave signals which are sensed by the brain wave sensor 20 after filtering the brain wave signals for removing noise
  • the brain wave signals are amplified by about 50,000
  • the analog-to-digital converter 32 samples the amplified brain wave signals of multiple channels 120 times per second and converts the brain wave signals into digital values
  • the encoder 33 sequentially codes an identifier of each channel and a one byte digital value of each channel in real time
  • the computer interface 34 transmits the digital signals which have been coded by the encoder 33 to a serial port of a computer
  • the serial port connector 40 is connected to the interface 30 via a cable
  • the serial port connector 40 may be a 9-p ⁇ n connector or a 25-p ⁇ n connector according to an RS232-C mode for connection to the serial port of the computer
  • FIG 3 shows the structure of a headband which is used in the brain wave measuring device
  • the center electrode is a ground electrode
  • the left two electrodes are used for measuring the brain wave of the frontal lobe of the left brain
  • the right two electrodes are used for measuring the brain wave of the frontal lobe of the right brain
  • Five wires which are connected to the electrodes are connected to the amplifier 31
  • the amplifier 31 amplifies the potential difference between the left two electrodes to calculate a brain wave signal of one channel and amplifies the potential difference between the right two electrodes to calculate a brain wave signal of the other channel
  • FIG 4 is a diagram for explaining a coding procedure by the brain wave measuring device After a character "A”, one byte of data of a channel 1 is located After a character "B”, one byte of data of a channel 2 is located After a character "C”, one byte of data of a channel 3 is located After a character "D”, one byte of data of a channel 4 is located
  • the characters are respective identifiers of the four channels Tl ⁇ e identifiers of the channels are used for minimizing a transmission error
  • a receiving terminal discards data in which an identifier of each channel is not identified
  • the brain wave signal which is coded in such format is transmitted 120 times per second so that a plurality of brain wave channels can be transmitted to the one serial port of the computer in real time
  • a brain wave analysis system may be implemented by computer software in the form of computer-readable program code, which is executed in a common computer such as a computer 4 as shown in FIG 5
  • a keyboard 50 and a mouse 51 are connected to a bidirectional system bus 60
  • the keyboard 50 and the mouse 51 are used to introduce user input into the computer system and transmit the user input to a central processing unit (CPU) 53
  • CPU central processing unit
  • Other proper input devices may be additionally used or substituted for the mouse 51 and the keyboard 50
  • An input/output (I/O) device 58 which is connected to the bidirectional system bus 60 represents an input/output element such as a serial/parallel port
  • the computer 4 includes a video memory 54, a main memory 55 and a mass storage unit 52 which are connected to the bidirectional system bus 60 along with the keyboard 50, the mouse 51 and the CPU 53
  • the mass storage unit 52 may include a removable medium such as a magnetic, optical or optical magnetic storage system, or other usable mass storage technology
  • the bus 60 may include, for example
  • the CPU 53 is a microprocessor, for example, the 680x0 made by Motorola, the 80x86 or Pentium processor made by Intel or the SPARC made by Sun Microsystems
  • the main memory 55 is implemented by a dynamic random access memory (DRAM)
  • the video memory ⁇ is a uusi port ranuom access memory U ⁇ port of the video memory 54 is connected to a video amplifier 56
  • the video amplifier 56 is very well known in the field of computer technology and can be easily implemented by any other appropriate device
  • the video amplifier 56 converts pixel data stored in the video memory 54 into a raster signal suitable for a monitor 57
  • the monitor 57 can be implemented by any monitor which is suitable for displaying graphic images
  • a real-time brain wave analysis system includes a brain wave data receiver 61 , a brain wave data transformer 62, a statistic data generator 63, a multigraph generator 64 and a multigraph output 65
  • the brain wave data receiver 61 receives brain wave data which has been measured and coded by the brain wave measuring device as shown in FIG 2
  • the brain wave data receiver 61 is implemented by an RS232-C mode serial input/output device
  • the brain wave data which is received by the brain wave data receiver 61 is temporarily stored in the main memory 55 of a computer and buffered
  • the brain wave data transformer 62 decodes the coded brain wave data, which is received by the brain wave data receiver 61 , and performs a fast Fourier transform on the decoded brain wave data
  • the statistic data generator 63 calculates mean values of the fast Fourier transformed brain wave data in the time and frequency domain, respectively
  • the multigraph generator 64 generates a real-time multigraph using the fast Fourier transformed brain wave data, the mean values in the time domain and the mean values in the frequency domain
  • FIGS 7 and 8 show the multigraph which is generated by the multigraph generator 64
  • a graph 5 of FIG 7 shows a brain wave signal in the time domain and is separately illustrated in FIG 9
  • the graph of FIG 9 shows the change in the amplitude of the brain wave with respect to time, based on the brain wave data decoded by the brain wave data transformer 62
  • the X-axis indicates time and the Y-axis indicates the amplitude of the brain wave
  • a graph 6 of FIG 7 is a bar graph in the frequency domain and is separately illustrated in FIG 10
  • brain wave amplitude values, accumulative mean values or mean values of respective samples in respective frequency bands of a delta wave, a theta wave, an alpha wave, a beta low wave and a beta high wave are represented by the heights of colored bars, using the mean values in the time domain and the mean values in the frequency domain which are obtained by the statistic data generator 63
  • An instantaneous value may be displayed at each measuring time or an accumulative mean value for a predetermined period
  • the multigraph generator 64 has the following characteristics 1 A unit of each graph is independently given in a separate window so that a user can selectively open or close each window displaying a graph 2 A mode of a maximum of 4 channels is supported so that measured rsin wSvc values of the channels can be compared and analyzed in real tune
  • Contents displayed on a screen are output or stored in a common format, which is independent from a device, such as a text file ( txt), a bit mapped file ( BMP) and a hexadecimal file (HEX), so that the contents can be reproduced by a usual editor or a graphic tool
  • the embodiments of the brain wave data transformer 62, the statistic data generator 63 and the multigraph generator 64 which construct a brain wave analysis system of a personal computer according to the present invention each can be made into a program which can be executed in a computer system
  • the programs can be read from a computer-readable medium and executed by a general purpose digital computer system
  • the computer-readable medium covers a storage medium such as a magnetic storage medium (e g , ROM, a floppy disk or a hard disk), an optical readable medium (e g , CD-ROM or DVD) or carrier wave (e g , transmission through internet)
  • Functional programs, code and code segments for the implementation of the present invention can be easily inferred by the programmers in the art of the present invention
  • the brain wave is simultaneously shown in the forms of a frequency/time/brain wave three-dimensional graph, a frequency band- based mean value/time two-dimensional graph, and a frequency band-based bar graph, thereby allowing the characteristics of the brain wave to be easily understood in real time

Abstract

A real-time brain wave analysis system and method are provided for analyzing real-time brain wave data measured by a brain wave measuring device in real time and providing the analyzed brain wave data to a user. The real-time brain wave analysis system includes a brain wave data receiver for receiving brain wave data which is measured and coded by an external brain wave measuring device, a brain wave data transformer for decoding the coded brain wave data which is received by the brain wave data receiver and fast Fourier transforming the decoded brain wave data, a statistic data generator for obtaining time domain mean values and frequency domain mean values with respect to the fast Fourier transformed brain wave data, a multigraph generator for generating a real-time multigraph using the fast Fourier transformed brain wave data, the time domain mean values and the frequency domain mean values, and a multigraph output for outputting the real-time multigraph to a display screen. Through frequency analysis and calculation of frequency band-based mean values as well as time-based analysis of a brain wave, the brain wave is simultaneously shown in the forms of a frequency/time/brain wave three-dimensional graph, a frequency band-based mean value/time two-dimensional graph, and a frequency band-based bar graph, thereby allowing the characteristics of the brain wave to be easily understood in real time.

Description

REAL-TIME BRAIN WAVE ANALYSIS SYSTEM AND METHOD USING FAST FOURIER TRANSFORM
Technical Field The present invention relates to a brain wave analysis system and method, and more particularly, to a real-time brain wave analysis system and method for analyzing real-time brain wave data measured by a brain wave measuring device in real time and providing the analyzed brain wave data to a user.
Background Art
A brain wave, which is measured at the scalp, is a wave having a potential difference of dozens of micro volts and a frequency of 30 Hz or less. The brain wave is a oh^sica! value ref!ectinπ a state of human consciousness. The brain wave is divided into an alpha wave, a beta wave, a theta wave and a delta wave. The beta wave has a frequency of at least 13 Hz and is related to usual action in which the five senses are functioning. The alpha wave has a frequency of 8-13 Hz and is related to a relaxed creative state. The theta wave has a frequency of 4-8 Hz and is often detected in adolescents having learning disorder. The delta wave has a frequency of 0.5-4 Hz and typically appears in a normal sleeping state. A lot of studies on the brain wave have been performed until now, but information contained in the brain wave is not sufficiently interpreted so that reading the brain wave is still a difficult problem.
Brain waves can be read in a time domain or a frequency domain. Reading of brain waves in a time domain requires a lot of experience and skill and it is very difficult to discriminate slight differences. For the method of analyzing the brain wave in the frequency domain, it is desired to process a measured signal such that the state of a subject can be easily read in real time.
Disclosure of the Invention
To solve the above problems, it is an objective of the present invention to provide a real-time brain wave analysis system and method for presenting various graphs which allow a user to easily read brain wave data which is measured by a brain wave measuring device
Accordingly, to achieve the above objective, there is provided a method for analyzing brain wave data in real time The method includes the steps of receiving brain wave data and storing it in a memory of a computer, fast Fourier transforming the brain wave data which is stored in the memory of the computer, obtaining mean values of the fast Fourier transformed brain wave in the time and frequency domains, and generating a real-time graph using the time and frequency domain mean values
In another aspect of the present invention, there is provided a system for analyzing brain wave data in real time The system includes a brain wave data receiver for receiving brain wave data which is measured and coded by an external brain wave measuπnq device a brain wave data transformer for decoding the coded brain wave data which is received by the brain wave data receiver and fast Fourier transforming the decoded brain wave data, a statistic data generator for obtaining time domain mean values and frequency domain mean values with respect to the fast Fourier transformed brain wave data, a multigraph generator for generating a real-time multigraph using the fast Fourier transformed brain wave data, the time domain mean values and the frequency αomain mean values, ana a muitigraph output for outputting the real-time multigraph to a display screen
Brief Description of the Drawings The above objective and advantages of the present invention will become more apparent by describing in detail preferred embodiments thereof with reference to the attached drawings in which
FIG 1 is a conceptional diagram showing an environment under which a real-time brain wave analysis system according to the present invention is used,
FIG 2 is a block diagram showing the structure of an embodiment of a brain wave measuring device for measuring brain wave data which is used in a real-time brain wave analysis system according to the present invention,
FIG 3 is a diagram showing the structure of a headband which is used in the brain wave measuring device,
FIG 4 is a diagram for explaining a coding procedure performed by the brain wave measuring device,
FIG 5 is a block diagram showing the hardware structure of a real-time brain wave analysis system according to an embodiment of the present invention,
FIG 6 is a block diagram showing the functional structure of a real-time brain wave analysis system according to an embodiment of the present invention,
FIG 7 shows an example of a multigraph which is displayed on a monitor of a real-time brain wave analysis system according to the present invention, FIG 8 shows another example of a multigraph which is displayed on a monitor of a real-time brain wave analysis system according to the present invention,
FIG 9 shows brain wave signals in the time domain, which are generated by a multigraph generator of FIG 6, FIG 10 is a bar graph based in the frequency domain, which is gsπerateu by a muitigrapi i generator oι no. o,
FIG. 11 is a three-dimensional graph of brain wave amplitude in the time and frequency domains, which is generated by a multigraph generator of FIG 6; and FIG 12 is a two-dimensional graph of brain wave mean values in the frequency domain during a predetermined period of time, which is generated by a multigraph generator of FIG. 6
Best mode for carrying out the Invention Referring to FIG 1 , a subject wears a headband 1 to which electrodes are attached, or cup electrodes 2 are attached on the subject's scalp Both the head band 1 and the cup electrodes 2 may be used together An interface 3 which is connected to the electrodes via a cable, then amplifies voltage of dozens of micro volts on the scalp up to voltage of several volts and converts the voltage into digital values A brain wave analysis system 4 encodes the digital values to be readable through a serial port The brain wave analysis system 4 performs a fast Fourier transform on brain wave signals and obtains the strength of the brain wave in each frequency band
FIG 2 shows a brain wave measuring device for measuring brain wave data, which is used in a brain wave analysis system according to the present invention Referring to FIG 2, the brain wave measuring device includes a brain wave sensor 20, an interface 30 and a serial port connector 40
The brain wave sensor 20 senses brain wave signals of four channels at predetermined portions on a subject's scalp using a plurality of electrodes In an embodiment of the present invention, the brain wave sensor 20 includes a headband having two channels and cup electrodes providing two channels The headband having two channels are used to conveniently measure the brain wave at the frontal lobe The cup electrodes providing two channels are used to selectively measure the brain wave at portions other than the frontal lobe, that is, the parietal lobe, the temporal lobe and the occipital lobe
The interface 30 is connected to the brain wave sensor 20 via a cable Preferably, a shielded line is used to prevent noise The interface 30 includes an amplifier 31 , an aπaiog-to-digitai convener 32, a encoder 33 and a computer interface 34 The amplifier 31 amplifies the amplitude of weak brain wave signals which are sensed by the brain wave sensor 20 after filtering the brain wave signals for removing noise The brain wave signals are amplified by about 50,000 The analog-to-digital converter 32 samples the amplified brain wave signals of multiple channels 120 times per second and converts the brain wave signals into digital values The encoder 33 sequentially codes an identifier of each channel and a one byte digital value of each channel in real time The computer interface 34 transmits the digital signals which have been coded by the encoder 33 to a serial port of a computer
The serial port connector 40 is connected to the interface 30 via a cable The serial port connector 40 may be a 9-pιn connector or a 25-pιn connector according to an RS232-C mode for connection to the serial port of the computer
FIG 3 shows the structure of a headband which is used in the brain wave measuring device When a subject wears the headband, five gold- plated electrodes which are attached to the band are stuck to the forehead (corresponding to the frontal lobe) Among the five electrodes, the center electrode is a ground electrode, the left two electrodes are used for measuring the brain wave of the frontal lobe of the left brain, and the right two electrodes are used for measuring the brain wave of the frontal lobe of the right brain Five wires which are connected to the electrodes are connected to the amplifier 31 For the five wires shielded lines are used for preventing noise The amplifier 31 amplifies the potential difference between the left two electrodes to calculate a brain wave signal of one channel and amplifies the potential difference between the right two electrodes to calculate a brain wave signal of the other channel
FIG 4 is a diagram for explaining a coding procedure by the brain wave measuring device After a character "A", one byte of data of a channel 1 is located After a character "B", one byte of data of a channel 2 is located After a character "C", one byte of data of a channel 3 is located After a character "D", one byte of data of a channel 4 is located The characters are respective identifiers of the four channels Tl ιe identifiers of the channels are used for minimizing a transmission error A receiving terminal discards data in which an identifier of each channel is not identified The brain wave signal which is coded in such format is transmitted 120 times per second so that a plurality of brain wave channels can be transmitted to the one serial port of the computer in real time
A brain wave analysis system according to the present invention may be implemented by computer software in the form of computer-readable program code, which is executed in a common computer such as a computer 4 as shown in FIG 5 A keyboard 50 and a mouse 51 are connected to a bidirectional system bus 60 The keyboard 50 and the mouse 51 are used to introduce user input into the computer system and transmit the user input to a central processing unit (CPU) 53 Other proper input devices may be additionally used or substituted for the mouse 51 and the keyboard 50 An input/output (I/O) device 58 which is connected to the bidirectional system bus 60 represents an input/output element such as a serial/parallel port The computer 4 includes a video memory 54, a main memory 55 and a mass storage unit 52 which are connected to the bidirectional system bus 60 along with the keyboard 50, the mouse 51 and the CPU 53 The mass storage unit 52 may include a removable medium such as a magnetic, optical or optical magnetic storage system, or other usable mass storage technology The bus 60 may include, for example, 32 address lines for addressing the video memory 54 or the main memory 55 The system bus 60 may include, for example, a 32-bιt data bus for transmission of data among elements such as the CPU 53, the main memory 55, the video memory 54 and the mass storage unit 52 Optionally, multiplexed data/address lines may substitute for the individual data lines and the address lines
In the embodiment of the present invention, the CPU 53 is a microprocessor, for example, the 680x0 made by Motorola, the 80x86 or Pentium processor made by Intel or the SPARC made by Sun Microsystems However, any other proper microprocessor or microcomputer can be used The main memory 55 is implemented by a dynamic random access memory (DRAM) The video memory ^ is a uusi port ranuom access memory UΠΘ port of the video memory 54 is connected to a video amplifier 56 The video amplifier 56 is very well known in the field of computer technology and can be easily implemented by any other appropriate device The video amplifier 56 converts pixel data stored in the video memory 54 into a raster signal suitable for a monitor 57 The monitor 57 can be implemented by any monitor which is suitable for displaying graphic images
Referring to FIG 6, a real-time brain wave analysis system according to the present invention includes a brain wave data receiver 61 , a brain wave data transformer 62, a statistic data generator 63, a multigraph generator 64 and a multigraph output 65
The brain wave data receiver 61 receives brain wave data which has been measured and coded by the brain wave measuring device as shown in FIG 2 Preferably, the brain wave data receiver 61 is implemented by an RS232-C mode serial input/output device The brain wave data which is received by the brain wave data receiver 61 is temporarily stored in the main memory 55 of a computer and buffered The brain wave data transformer 62 decodes the coded brain wave data, which is received by the brain wave data receiver 61 , and performs a fast Fourier transform on the decoded brain wave data The statistic data generator 63 calculates mean values of the fast Fourier transformed brain wave data in the time and frequency domain, respectively The multigraph generator 64 generates a real-time multigraph using the fast Fourier transformed brain wave data, the mean values in the time domain and the mean values in the frequency domain
FIGS 7 and 8 show the multigraph which is generated by the multigraph generator 64 A graph 5 of FIG 7 shows a brain wave signal in the time domain and is separately illustrated in FIG 9 The graph of FIG 9 shows the change in the amplitude of the brain wave with respect to time, based on the brain wave data decoded by the brain wave data transformer 62 In the graph, the X-axis indicates time and the Y-axis indicates the amplitude of the brain wave A graph 6 of FIG 7 is a bar graph in the frequency domain and is separately illustrated in FIG 10 According to the graph shown m FiG 10, brain wave amplitude values, accumulative mean values or mean values of respective samples in respective frequency bands of a delta wave, a theta wave, an alpha wave, a beta low wave and a beta high wave, are represented by the heights of colored bars, using the mean values in the time domain and the mean values in the frequency domain which are obtained by the statistic data generator 63 An instantaneous value may be displayed at each measuring time or an accumulative mean value for a predetermined period of time by a user may be displayed A graph 7 of FIG 7 is a three-dimensional graph of brain wave amplitude in the time and frequency domains and separately illustrated in FIG 11 In the graph, the X-axis indicates time, the Y-axis indicates frequency and the Z-axis indicates the amplitude of the brain wave The graph of FIG 11 is updated by the mean values in the time domain and the mean values in the frequency domain obtained by the statistic data generator 63 An updating rate and the number of samples can be adjusted at a user's discretion A graph 8 of FIG 8 is a two-dimensional graph of brain wave mean values in the frequency domain during a predetermined period of time and separately illustrated in FIG 12 In other words, the graph of FIG 12 shows temporal change of a mean value of brain wave amplitude of each frequency band for a period of time predetermined by a user, through a two-dimensional graph The X-axis indicates time and the Y-axis indicates the amplitude of the brainwave The curved lines indicate changes in amplitude of each frequency band Since a mean value of each frequency band is displayed in real time, this graph is advantageous in tracking the change of a brain wave of a particular frequency with respect to time The number and types of frequencies to be displayed through the graph are determined in accordance with the selection by the user
The multigraph generator 64 has the following characteristics 1 A unit of each graph is independently given in a separate window so that a user can selectively open or close each window displaying a graph 2 A mode of a maximum of 4 channels is supported so that measured rsin wSvc values of the channels can be compared and analyzed in real tune
3 A variety of scale functions are supported so that a user can manipulate a graph to make a form which is easily understood
4 Contents displayed on a screen are output or stored in a common format, which is independent from a device, such as a text file ( txt), a bit mapped file ( BMP) and a hexadecimal file ( HEX), so that the contents can be reproduced by a usual editor or a graphic tool
5 Data is stored and reproduced so that graphs can be repeatedly output The embodiments of the brain wave data transformer 62, the statistic data generator 63 and the multigraph generator 64 which construct a brain wave analysis system of a personal computer according to the present invention, each can be made into a program which can be executed in a computer system The programs can be read from a computer-readable medium and executed by a general purpose digital computer system The computer-readable medium covers a storage medium such as a magnetic storage medium (e g , ROM, a floppy disk or a hard disk), an optical readable medium (e g , CD-ROM or DVD) or carrier wave (e g , transmission through internet) Functional programs, code and code segments for the implementation of the present invention can be easily inferred by the programmers in the art of the present invention
Industrial Applicability
According to the present invention, through frequency analysis and calculation of frequency band-based mean values as well as time-based analysis of a brain wave, the brain wave is simultaneously shown in the forms of a frequency/time/brain wave three-dimensional graph, a frequency band- based mean value/time two-dimensional graph, and a frequency band-based bar graph, thereby allowing the characteristics of the brain wave to be easily understood in real time

Claims

What is claimed is
1 A method of analyzing brain wave data in real time, the method comprising the steps of receiving brain wave data and storing it in a memory of a computer, fast Fourier transforming the brain wave data which is stored in the memory of the computer, obtaining mean values of the fast Fourier transformed brain wave in the time and frequency domains, and generating a real-time graph using the time and frequency domain mean values
2 A system for analyzing brain wave data in real time, the system comprising a brain wave data receiver for receiving brain wave data which is measured and coded by an external brain wave measuring device, a brain wave data transformer for decoding the coded brain wave data which is received by the brain wave data receiver and fast Fourier transforming the decoded brain wave data, a statistic data generator for obtaining time domain mean values and frequency domain mean values with respect to the fast Fourier transformed rain w5v6 data, a multigraph generator for generating a real-time multigraph using the fast Fourier transformed brain wave data, the time domain mean values and the frequency domain mean values, and a multigraph output for outputting the real-time multigraph to a display screen
3 The system of claim 2, wherein the multigraph comprises a frequency/time/brain wave three-dimensional graph in which amplitude of the brain wave is represented by different heights and colors on a frequency/time plane, thereby presenting a three-dimensional representation of the brain wave 4 The system of claim 2, wherein the multigraph comprises a frequency domain mean value/time two-dimensional graph for showing a temporal change of a mean value of brain wave amplitude, and the mean value is obtained in the frequency domain for a period of time predetermined by a user
5 The system of claim 2, wherein the multigraph comprises a bar graph for showing brain wave amplitude of each frequency band in the form of bars
6 The system of claim 2, wherein the brain wave data receiver is a serial input/output device employing a RC232-C mode
PCT/KR2000/000074 1999-03-23 2000-01-29 Real-time brain wave analysis system and method using fast fourier transform WO2000056212A1 (en)

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KR1019990009823A KR20000006606A (en) 1999-03-23 1999-03-23 Real-time brain wave analysis system using FFT and method thereof

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