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  • devidasbhonde
    Sir, I am from India. I wish to build the EEG biofeedback HW & SW. (I am an electronics engineer) Does it allow the user to try to increase his perticular
    Message 1 of 7 , Jun 15, 2003
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      Sir,

      I am from India.
      I wish to build the EEG biofeedback HW & SW.
      (I am an electronics engineer)
      Does it allow the user to try to increase his perticular
      (predominent) frequencies ? say 13Hz.

      How do I start?
      Please help me.

      Regards,

      Devidas
    • A.Jayaprakash Narayanan
      iam busy right now please remind me after 15 days i will help you please send me your resume thanks ... __________________________________ Do you Yahoo!? SBC
      Message 2 of 7 , Jun 15, 2003
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        iam busy right now
        please remind me after 15 days
        i will help you
        please send me your resume
        thanks

        --- devidasbhonde <devidasbhonde@...> wrote:
        > Sir,
        >
        > I am from India.
        > I wish to build the EEG biofeedback HW & SW.
        > (I am an electronics engineer)
        > Does it allow the user to try to increase his
        > perticular
        > (predominent) frequencies ? say 13Hz.
        >
        > How do I start?
        > Please help me.
        >
        > Regards,
        >
        > Devidas
        >
        >
        >


        __________________________________
        Do you Yahoo!?
        SBC Yahoo! DSL - Now only $29.95 per month!
        http://sbc.yahoo.com
      • Richard Fisher
        Hello, I am right in the middle of a Tom Silver seminar weekend, but I ll get back to you soon! Thanks for contacting me.... The machine simply shows the
        Message 3 of 7 , Jun 15, 2003
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          Hello,
          I am right in the middle of a Tom Silver seminar weekend, but I'll get back to you soon! Thanks for contacting me....
          The machine simply shows the user's brainwave activity in Hz.
          So from the deepest hypnotic state - 0.1Hz (Delta) right up to 60 Hz - the highest waking state.
          Take a look at
          http://www.advanced-hypnosis.co.uk and click on the name Tom Silver.
          Look at the top picture on the right.
          I'll send you more details and I attach a picture
          Regards
          Richard Fisher

          devidasbhonde wrote:

           Sir,

          I am from India.
          I wish to build the EEG biofeedback HW & SW.
          (I am an electronics engineer)
          Does it allow the user to try to increase his perticular
          (predominent) frequencies ? say 13Hz.

          How do I start?
          Please help me.

          Regards,

          Devidas
           
           


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        • Joerg Hansmann
          ... First thing: subscribe to openeeg-list this group here has moved to : http://lists.sourceforge.net/lists/listinfo/openeeg-list Regards, Joerg
          Message 4 of 7 , Jun 16, 2003
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            devidasbhonde wrote:
            > Sir,
            >
            > I am from India.
            > I wish to build the EEG biofeedback HW & SW.
            > (I am an electronics engineer)
            > Does it allow the user to try to increase his perticular
            > (predominent) frequencies ? say 13Hz.
            >
            > How do I start?
            > Please help me.


            First thing: subscribe to openeeg-list

            this group here has moved to :

            http://lists.sourceforge.net/lists/listinfo/openeeg-list

            Regards,

            Joerg
          • Richard Fisher
            Hi again, The machine has a band that goes around the head. There are 3 metal contact sensors that touch the forehead. These are fed to a small transmitter
            Message 5 of 7 , Jun 17, 2003
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              Hi again,
              The machine has a band that goes around the head.
              There are 3 metal contact sensors that touch the forehead.
              These are fed to a small transmitter that transmits to a receiver that
              is plugged into the computer.
              It shows the activity of the brainwaves from 0 Hz up to 30 or even 60
              Hz.
              When the only active brainwaves are the 0 - 4 Hz, then we know that the
              subject is in deep hypnosis.
              I had an idea today.
              As the sensors are picking up the activity, would it be possible to
              record that acitivity, and then transmit the recording to a wide-awake
              subject to induce hypnosis artificially?
              If you are able to make this machine, then we could do some very good
              business....!
              Best regards,
              Richard
              The Advanced Hypnosis Institute.
              44 (0)1225 443020
            • A.Jayaprakash Narayanan
              Hey thanks can you mail the circuit for the EEG you have used i want to build my own with off the shelf parts please help me __________________________________
              Message 6 of 7 , Jun 17, 2003
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                Hey
                thanks
                can you mail the circuit for the EEG you have used
                i want to build my own with off the shelf parts
                please help me


                __________________________________
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                SBC Yahoo! DSL - Now only $29.95 per month!
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              • hrebesh ms
                BRAIN TURNS CHAOTIC Introduction: Chaos as oxford dictionary states “utter confusion” however from an analytical point of view of a researcher chaos is how
                Message 7 of 7 , Jun 26, 2003
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                  BRAIN TURNS CHAOTIC

                   

                  Introduction:

                   

                  Chaos as oxford dictionary states “utter confusion” however from an analytical point of view of a researcher chaos is how something evolves over time, space or distance. Chaos is sustained and disorderly looking longterm evolution that satisfies certain mathematical criteria and which occurs in a deterministic nonlinear system.

                   

                  "Physicists like to think that all you have to do is say, these are the conditions, now what happens next?"

                   

                  The only systems to be examined in the past were those that were governed by the principles of  linearity for eg. Linear algebra, Linear accelerator, Linear functions i.e those systems which follow predictable patterns and arrangement. These have been mastered by humans for centuries but the problem arises that we exist in a nonlinear world, which is undergoing random and rapid evolution every second. Virtually anything that evolves over time can be chaotic. Epidemics, Population, Droughts, Rainfall rates and so on. The human brain is also susceptible to this bizarre yet realistic concept of chaos. In this paper certain nonlinear techniques have been analyzed keeping in mind the final goal to analyze the “Black Box” (Human Brain) through EEG analysis. This will enable us to understand the interdependencies in the cortical areas while performing cognitive tasks. Understanding chaos will enable us to solve the unsolved mysteries of life as Stephen Hawking once said, "If we find the answer to that (the universe), it would be the ultimate triumph of human reason-for then we would know the mind of God.

                   

                   

                   

                  CAUSES OF CHAOS:

                   

                  There have not been any concrete evidences to explain the occurrence of chaos in nature however three possible causes have been proposed.

                   

                  Ø      An  increase in a control factor beyond a critical value 

                                   sets  chaos eg. Iterations of various sorts, Rayleigh Benard experiment, Belousov      

                                   Zhabotinsky experiment.

                                

                  Ø      The nonlinear interaction of two or more separate

                                    physical operations.

                   

                  Ø      The presence of noise on otherwise regular motion.

                   

                   

                  BENEFITS OF ANALYSING CHAOS:

                   

                  Ø      Analyzing data for chaos will enable us to segregate whether  haphazard looking fluctuation actually represent an orderly system.

                   

                  Ø      It gives greater accuracy for short term predictions eg.Weather  forecasts.

                   

                  Ø      Chaos analysis enables us to detect the limit (critical point)Beyond which the results become futile.

                   

                  Ø      Recognising chaos makes modeling easier.

                   

                  The benefits of analyzing chaos are infinite. It will give a new dimension to the present world. Diseases would be predicted before their onset, the future could be predicted before the present.

                   

                   

                   

                  NONLINEAR TECHNIQUES:

                  LOGISTIC  MAPS:

                   

                  These consist of simple difference equations which give a large amount of information about the behaviour that is common to an entire class of real dynamical systems. The logistic map difference equation is of the form:

                   

                  Xn+1=lambda*Xn*(1-Xn) – Eq1

                   

                   

                  Here lambda is the control parameter which can be adjusted. Let us start off with an initial condition X0 putting it in RHS we get X1 as the output now repeatedly iterating by treating X1 as the new input and placing it on RHS we get X2 as the output and so on.

                  Logistic map is a discrete version of corresponding continuous differential equation introduced by PF Verhulst to model population growth subjected to limited resources. If we start with an initial value of Xn between 0 and 1 the final value also lies in the same unit interval. Since Xn+1 is obtained from previous value Xn by multiplying it by lambda*(1-Xn) therefore it is obvious that for lambda*(1-Xn) greater than 1, the successive values grow bigger and bigger. The constant lambda governs the steepness and height of parabola above the absicca.

                   

                  Low Parameter Values.

                   

                  First let lambda=0.5 then Eq1 becomes Xn+1=0.5*Xn*(1-Xn).

                  Let us assume Xn=0.01 then inserting this arbitary value into the logistic equation the first solution of the equation yields Xn+1=0.5*(0.01)*(1-0.01)=0.00495 for second iteration we give 0.00495 as the new input and we get X2=0.00246 and thus proceeding we get 0.00122,0.00612,0.00306 and so on. The values converge to 0.It is remarkably evident that with lambda=0.5 and any other Xn the value still converges to zero. The point zero attracts all computed points. It is therefore called an attractor.

                   

                   

                  Intermediate Parameter Values 

                   

                  Now if we repeat the iteration with a different value of lambda say 1.5 and Xn=0.01 then let’s see what happens. The values converge to a single point located at X~0.333.It turns out that for our chosen value of lambda the point of convergence is 0.333 disregardless of  Xn as long as Xn is not equal to zero.

                   

                  Higher Parameter Values

                   

                  When lambda>3.0 the trajectory no longer converges to a single value of X. The trajectory becomes more and more sensitive to lambda. If lambda =3.4 then regardless of our chosen Xn the iterations  converge to two values alternately namely X1=0.452 and X2=0.842.This constitutes two point attractor and similarly increasing the value of lambda to 3.5 gives four point attractors and so on until we reach the critical value of lambda=3.5699………,where the period becomes infinite. The motion has become aperiodic. It never quite repeats itself. This is the onset of Chaos.

                   

                  A simple Matlab program to generate logistic map.

                   

                  Lambda=3.7

                  X(1)=0.01;

                  For i=1:1000

                  X(i+1) =lambda*X(i)* (1-X(i));

                  End

                  Plot(X(1:i),X(2:i+1))

                   

                   

                  COHERENCE:

                   

                  Our brain talks to  itself to decipher the complexity of the world and to make an execute decisions which best suit the situation. Coherence is the EEG measurement of how efficiently brain is able to perform this self task.

                   

                  Brain rapidly connects and disconnects different parts to itself. Excessive coherence measurement in the QEEG indicates two or more areas of the brain are fused together and not able to process or execute the information. Deficient coherence on the other hand implies that the brain is not able to efficiently connect cortical areas to perform the task. Coherence enables us to investigate the degree of interdependencies between different cortical areas while listening to different pieces of music. A simple program can be written to determine the degree of coherence between different channels and thus make a hypothesis as to which are the functional areas of the brain while listening to different types of music.

                   

                   

                   

                   

                  PROGRAM  FOR COHERENCE USING INBUILT MATLAB FUNCTION:

                  To analyse the coherence between two channels of EEG signal.

                   

                  Load trial1.txt

                  Time=trial1(:,1);

                  Fp1=trial1(:,2);

                  Y=fft(fp1);

                   

                  Load trial2.txt

                  Time=trial2(:,1);

                  Fp2=trial2(:,2);

                  Y=fft(fp2);

                  Figure(1),cohere(fp1,fp2)

                   

                  EEG

                   

                  The term Electroencephalogram was introduced by german psychiatrist Hans Berger to denote the recording of variations in potential recorded from the brain. EEG can be recorded with scalp electrodes through the unopened skull or with electrodes on or in the brain. The term electrocorticogram is sometimes used to refer to the record obtained with electrodes on the pial surface of the cortex. EEG records may be bipolar or unipolar. Bipolar records show fluctuations in potential between two cortical electrodes, unipolar records show potential difference between cortical electrode and a theoretically indifferent electrode on some part of the body distant from the cortex.

                   

                  A powerful electronic amplifier increases several hundreds or thousands of times the amplitude of the weak signal (less than a few microvolts) which is generated in this place. A device called galvanometer, writes on the surface of a paper strip, which moves continuously at a fixed speed past it. The result is a wiggly "wave". One pair of electrodes usually make up a  channel. EEG recordings, depending on its use, can have from 8 to 40 channels recorded in parallel. This is called multichannel EEG recording.

                   

                   

                   

                   

                   

                   

                  THE 10-20 SYSTEM OF ELECTRODE PLACEMENT

                   

                  The 10-20 system of electrode placement is a method used to describe the location of scalp electrodes. The electrodes record the electroencephalogram using a machine called as an

                  Electroencephalograph. The signal is a result of the excitation of thousands of neurons in the brain. The pattern of activity changes with the level of a persons arousal. If a person is relaxed then EEG shows many slow waves, if a person is excited, then the EEG shows fast waves. EEG is used for many purpose including the diagnosis of epilepsy.

                   

                  The 10-20 system is based on the relationship between the location of an electrode and the underlying area of cerebral cortex. Each site has a letter to identify the lobe and a number which designates the hemisphere location. F-frontal, T-temporal,C-central, P-parietal, O-occipital. Even numbers denote right hemisphere whereas odd numbers denote left hemisphere. Z refers to the electrode placed at midline. The 10-20 system refers to 10% or 20% interelectrode distance.

                   

                  CONCLUSION

                   

                  Thus one can see that the development of new nonlinear measures has enhanced our capabilities to investigate EEG studies in higher cognitive functions. These methods not only stress the existent of differences between different cortical areas while performing various tasks, but also show promising interdependencies between multiple cortical areas. The results are encouraging and may help us to solve the unsolved mysteries of neuronal disorders.

                   

                   



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