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Alpha/Theta feedback

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  • Joerg Hansmann
    Hi, since about 5 days I am using the comEEG prototype for Alpha/Theta audio-feedback. Electrode positions for 1 channel are Cz - A2 (A2 should be right ear
    Message 1 of 13 , Sep 2, 2001
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      Hi,

      since about 5 days I am using the comEEG prototype for
      Alpha/Theta audio-feedback. Electrode positions for
      1 channel are Cz - A2
      (A2 should be right ear lobe. Is that right ? My picture with electrode-
      positions is a little bit unclear).

      Audio-feedback is given using two sine-wave oscillators (one lower
      frequency for Theta and one higher frequency to indicate Alpha)
      which amplitudes are controlled by the geometric addition
      (root sum of squares) of the FFT output for each frequency band.

      If a (fixed) threshold of 25uV is met, the feedback sound
      is played at a low volume. A voltage between 25uV and 50uV increases
      the volume and everything above 50uV is played at maximum volume.

      With this setup I have been able to increase Alpha (lying position, eyes
      closed), so that the Alpha-feedback sound is played nearly 100% of time.

      However I have no idea how to get significant Theta.

      What am I doing wrong ?
      Should I train Alpha with higher thresholds first ?

      And what is the great difference in
      inner perception between Alpha and Theta ?


      Regards,

      Joerg
    • yaniv_vi@yahoo.com
      hi is sound great , working with open eeg . how do you feel ? how s alpha feedback feels ? yaniv ... increases ... eyes ... time.
      Message 2 of 13 , Sep 2, 2001
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        hi
        is sound great , working with open eeg .
        how do you feel ? how's alpha feedback feels ?

        yaniv
        --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
        > Hi,
        >
        > since about 5 days I am using the comEEG prototype for
        > Alpha/Theta audio-feedback. Electrode positions for
        > 1 channel are Cz - A2
        > (A2 should be right ear lobe. Is that right ? My picture with electrode-
        > positions is a little bit unclear).
        >
        > Audio-feedback is given using two sine-wave oscillators (one lower
        > frequency for Theta and one higher frequency to indicate Alpha)
        > which amplitudes are controlled by the geometric addition
        > (root sum of squares) of the FFT output for each frequency band.
        >
        > If a (fixed) threshold of 25uV is met, the feedback sound
        > is played at a low volume. A voltage between 25uV and 50uV
        increases
        > the volume and everything above 50uV is played at maximum volume.
        >
        > With this setup I have been able to increase Alpha (lying position,
        eyes
        > closed), so that the Alpha-feedback sound is played nearly 100% of
        time.
        >
        > However I have no idea how to get significant Theta.
        >
        > What am I doing wrong ?
        > Should I train Alpha with higher thresholds first ?
        >
        > And what is the great difference in
        > inner perception between Alpha and Theta ?
        >
        >
        > Regards,
        >
        > Joerg
      • frans smith
        Hi Joerg how are you ?, I i m not sure wheter i understand the question. (is it a technical question or related to medtitation ?) From your writting i get
        Message 3 of 13 , Sep 2, 2001
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          Hi Joerg how are you  ?,
           
          I i'm not sure wheter  i understand the  question.
          (is it a technical question or related to medtitation ?)
          From your writting i get the impression you cannot
          do theta training, that is you don't produce theta ?
           
          1. I thougth the EEG should be adjusted to filter Alpha
          so as to give feedback to the practionar.
          2. If theta is the main goal, then the same for theta.
          3. If you would like to enter these states, then naturally
             (i guess) the first step is to become familliar with re-
             laxation (alpha).  However, from what i know, alpha can
             be improved at different places (front, back).
             If you do first relaxation, then if correct you automaticly
             enter alpha state, that is if you don't let your thougths
             up-set you. (visualize something nice).
             Alpha is if i'm rigth a state before sleeping, but it's easy
             to learn to enter this state and then use the state for
             programming yor-self etc.
          4. Theta goes deeper, one must be good in meditation or
              self-hypnosis. On the other hand, the use of software
              can speed up this process. Theta is seen in hypnosis,
              and sleep. I guess if you want theta, then you must be
              able to meditate. When you close your eyes alpha is
              present, if you just relax alpha is present, but perhaps
              you should learn meditation or mind-control to reach the
              theta state.
          5. Inner perception: If in alpha on must try and "feel" this
              state to learn the different between tension and relax,
              the inner state then in theta is not easy to explain.
              From what i know, some people have evil images, while
              others have visions, i don' t know. It is said one comes
              (or can) come in cntact with the sub-conciousness.
              When i did a course in Silva Mind Control, they used
              a sort of hypnosis to "program" us to reach that state.
              i'm not sure wheter i did. In theta it had to be possible
              to do "arm levitation" that is without normal force, the
              arm would rise due to suggestion. Few claimed they
              could do it, but i'm not sure. it can be done however, but
              you must use kind of protocoll to relax and go deeper
              in trance, EEG only gives information on your progress.
              Inner perception is (i guess) someting you can only
              experience and tell for your self. Try to find a book of
              Silva mind control by Jose Silva.
           
          Regards
          Frans.
          5.
          ----- Original Message -----
          Sent: Sunday, September 02, 2001 1:41 PM
          Subject: [buildcheapeeg] Alpha/Theta feedback

          Hi,

          since about 5 days I am using the comEEG prototype for
          Alpha/Theta audio-feedback. Electrode positions for
          1 channel are Cz - A2
          (A2 should be right ear lobe. Is that right ? My picture with electrode-
          positions is a little bit unclear).

          Audio-feedback is given using two sine-wave oscillators (one lower
          frequency for Theta and one higher frequency to indicate Alpha)
          which amplitudes are controlled by the geometric addition
          (root sum of squares) of the FFT output for each frequency band.

          If a (fixed) threshold of 25uV is met, the feedback sound
          is played at a low volume. A voltage between 25uV and 50uV increases
          the volume and everything above 50uV is played at maximum volume.

          With this setup I have been able to increase Alpha (lying position, eyes
          closed), so that the Alpha-feedback sound is played nearly 100% of time.

          However I have no idea how to get significant Theta.

          What am I doing wrong ?
          Should I train Alpha with higher thresholds first ?

          And what is the great difference in
          inner perception between Alpha and Theta ?


          Regards,

          Joerg  



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          buildcheapeeg-unsubscribe@egroups.com



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        • frans smith
          ... From: Joerg Hansmann To: buildcheapeeg@yahoogroups.com Sent: Sunday, September 02, 2001 1:41 PM Subject: [buildcheapeeg] Alpha/Theta feedback Hi,
          Message 4 of 13 , Sep 2, 2001
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            ----- Original Message -----
            Sent: Sunday, September 02, 2001 1:41 PM
            Subject: [buildcheapeeg] Alpha/Theta feedback

            Hi,

            Alpha/Theta audio-feedback. Electrode positions for
            1 channel are Cz - A2
            (A2 should be right ear lobe. Is that right ? My picture with electrode-
            positions is a little bit unclear).
            **** Peterson wrote once that he would scan a map
                  for finding the correct point.
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          • Joerg Hansmann
            Hi frans , ... From: frans smith To: Sent: Sunday, September 02, 2001 2:55 PM Subject: Re: [buildcheapeeg]
            Message 5 of 13 , Sep 2, 2001
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              Hi frans ,

              ----- Original Message -----
              From: frans smith <f.smith@...>
              To: <buildcheapeeg@yahoogroups.com>
              Sent: Sunday, September 02, 2001 2:55 PM
              Subject: Re: [buildcheapeeg] Alpha/Theta feedback


              >Hi Joerg how are you ?,

              Thanks ;-)

              >I i'm not sure wheter i understand the question.
              >(is it a technical question or related to medtitation ?)

              It is more related to meditation.

              The technical stuff was intended for the feedback-experts
              here to check out, if I have made some obvious mistakes
              in electrode placement or protocol implementation.

              >From your writting i get the impression you cannot
              >do theta training, that is you don't produce theta ?

              That is right.
              The Theta feedback sound occurred very rare and short
              in my Alpha/Theta sessions.

              >
              >1. I thougth the EEG should be adjusted to filter Alpha
              >so as to give feedback to the practionar.
              >2. If theta is the main goal, then the same for theta.

              I have used a combined Alpha/Theta protocol that Elmer and
              Alice Green have presented in the book "Beyond Biofeedback".
              IIRR Peniston has made a similar approach for the EEG-feedback
              part of his protocol.

              With Theta feedback only I have got no better results than with
              Alpha/Theta feedback.


              >3. If you would like to enter these states, then naturally
              > (i guess) the first step is to become familliar with re-
              > laxation (alpha).

              ACK.

              > However, from what i know, alpha can
              > be improved at different places (front, back).

              So I should reconsider the electrode placement ?

              > If you do first relaxation, then if correct you automaticly
              > enter alpha state, that is if you don't let your thougths
              > up-set you. (visualize something nice).

              Deliberately concentrating on anything (pictures etc.) immediately
              cancels Alpha and lets me fall back to Beta.

              > Alpha is if i'm rigth a state before sleeping, but it's easy
              > to learn to enter this state

              ACK.

              > and then use the state for
              > programming yor-self etc.

              By using inner speech with positive suggestions ? (Like in autogenic training
              or self hypnosis ?)

              >
              >4. Theta goes deeper, one must be good in meditation or
              > self-hypnosis. On the other hand, the use of software
              > can speed up this process.

              I hope so...

              > Theta is seen in hypnosis,
              > and sleep. I guess if you want theta, then you must be
              > able to meditate.

              There are many kinds of meditation. Would Vipassana
              be suitable ?

              > When you close your eyes alpha is
              > present,

              Yes. After a few seconds.

              > if you just relax alpha is present, but perhaps
              > you should learn meditation or mind-control

              Silva mind control with counting into relaxation states ?

              > to reach the
              > theta state.
              >
              >5. Inner perception: If in alpha on must try and "feel" this
              > state to learn the different between tension and relax,

              In my experience tension is the direct result of will and desire.

              > the inner state then in theta is not easy to explain.

              Have you experienced Theta during meditation ?

              > From what i know, some people have evil images, while
              > others have visions, i don' t know.

              Yes. I have read of "interesting" hypnogogic imagery
              similar to those induced by psychedelic drugs like
              LSD or mushrooms.

              >
              > It is said one comes
              > (or can) come in cntact with the sub-conciousness.

              That is why I am especially interested in Theta.

              > When i did a course in Silva Mind Control, they used
              > a sort of hypnosis to "program" us to reach that state.
              > i'm not sure wheter i did. In theta it had to be possible
              > to do "arm levitation" that is without normal force, the
              > arm would rise due to suggestion. Few claimed they
              > could do it, but i'm not sure. it can be done however, but
              > you must use kind of protocoll to relax and go deeper
              > in trance, EEG only gives information on your progress.
              > Inner perception is (i guess) someting you can only
              > experience and tell for your self. Try to find a book of
              > Silva mind control by Jose Silva.

              I have read some books written by Silva. However I did not
              have the impression that the counting technique worked
              very well for me. Also I am not skilled in imagination of
              inner pictures.


              Regards,

              Joerg
            • Joerg Hansmann
              Hi yaniv, ... From: To: Sent: Sunday, September 02, 2001 2:21 PM Subject: [buildcheapeeg] Re: Alpha/Theta
              Message 6 of 13 , Sep 2, 2001
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                Hi yaniv,

                ----- Original Message -----
                From: <yaniv_vi@...>
                To: <buildcheapeeg@yahoogroups.com>
                Sent: Sunday, September 02, 2001 2:21 PM
                Subject: [buildcheapeeg] Re: Alpha/Theta feedback


                > hi
                > is sound great , working with open eeg .
                > how do you feel ? how's alpha feedback feels ?

                When I manage to get the Alpha-feedback sound constant
                with maximum amplitude for a while, my body is in a relaxed
                state with slow breath and enhanced peripheral bloodflow.
                (e.g. warm feeling in hands and feet )

                It is a state with calm emotions without willing or wanting
                and a relaxed focus. (In fact each time I tried to focus
                on different features of the current state, I fell back into Beta)

                Thinking is possible but somehow "light" (opposed to a kind
                of heavyness in the waking state).
                Another observation is that the feeling of myself (the "I") is
                diminished and replaced by some sort of emptiness.

                There were no spontaneous inner pictures or memories.


                Regards,

                Joerg
              • frans smith
                ... From: Joerg Hansmann To: buildcheapeeg@yahoogroups.com Sent: Monday, September 03, 2001 1:07 AM Subject: Re: [buildcheapeeg] Alpha/Theta feedback Hi ...
                Message 7 of 13 , Sep 2, 2001
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                  ----- Original Message -----
                  Sent: Monday, September 03, 2001 1:07 AM
                  Subject: Re: [buildcheapeeg] Alpha/Theta feedback

                  Hi
                   
                  ----- Original Message -----
                  From: frans smith <f.smith@...>
                  To: <buildcheapeeg@yahoogroups.com>
                  Sent: Sunday, September 02, 2001 2:55 PM
                  Subject: Re: [buildcheapeeg] Alpha/Theta feedback



                  The technical stuff was intended for the feedback-experts
                  here to check out, if I have made some obvious mistakes
                  in electrode placement or protocol implementation.
                  **I see.


                  >  However, from what i know, alpha can
                  >   be improved at different places (front, back).

                  So I should reconsider the electrode placement ?
                   
                  **don't know. all depends (i guess)wheter
                    you are using eeg for altering states.
                    or using eeg for neurofeedback therapy.


                  Deliberately concentrating on anything (pictures etc.) immediately
                  cancels Alpha and lets me fall back to Beta.
                   
                  **strange. when reading a book, or visu-
                  alizing someting nice, like walking in
                  the woods, would normaly bring you into alpha.
                  By concentraing one can activate smr/low beta, could
                  this be the case ?
                   
                  By using inner speech with positive suggestions ? (Like in autogenic training or self hypnosis ?)
                   
                  **yes.

                  There are many kinds of meditation. Would Vipassana be suitable ? 
                   
                  ** i guess so.


                  Have you experienced Theta during meditation ?
                   
                  no, not really. however years ago i did
                  use theta-brain tapes (sound) to reach
                  the theta state.
                  But as i have experienced my-self, one
                  must not do such a thing unless one is
                  mental healthy (no heavy stress, depres-
                  sions etc). For it could make things worse.
                   
                  Yes. I have read of "interesting" hypnogogic imagery
                  similar to those induced by psychedelic drugs like
                  LSD or mushrooms.
                   
                  **some refer to the sub-concious as the
                    main reason for evil experiences. The
                    sub-concious holds your traumatic ex-
                    periences.
                   
                  That is why I am especially interested in Theta.
                   
                  ** In that case you could use braintapes.
                     However, you could use eeg to guide 
                     you, give feedback. I have once post a
                     design from 1970, this design is not
                     for nfb, but i only tells you about
                     the state your are in (alpha, theta).
                     Using the rs232, you don't need to do
                     a combination a waves, but first only
                     alpha training, afther succesfull trai
                     ning you would go further in to theta.
                     Then the eeg should only give feedback
                     on theta-state.
                    
                  I have read some books written by Silva. However I did not
                  have the impression that the counting technique worked
                  very well for me.
                   
                  ** I think autogene training is better,
                     but it takes a long time.
                   
                  Also I am not skilled in imagination of
                  inner pictures.
                   
                  ** I have the same, but it is a skill
                     every body can learn. In fact it's
                     like training a muscle. it a normal
                     ability for everyone, but some need
                     to activate this.


                  Regards,

                  Frans.




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                • Vladimir.K
                  Hi Joerg, ... electrode- ... There is illustrative pictures of electrode placement: http://faculty.washington.edu/chudler/1020.html I hope, this will help you.
                  Message 8 of 13 , Sep 3, 2001
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                    Hi Joerg,

                    --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
                    > Hi,
                    >
                    > since about 5 days I am using the comEEG prototype for
                    > Alpha/Theta audio-feedback. Electrode positions for
                    > 1 channel are Cz - A2
                    > (A2 should be right ear lobe. Is that right ? My picture with
                    electrode-
                    > positions is a little bit unclear).

                    There is illustrative pictures of electrode placement:

                    http://faculty.washington.edu/chudler/1020.html

                    I hope, this will help you.

                    By the way, what variant of analog part EEG are you using ?
                    Do you generate tones by PC sound card ?

                    Regards
                    Vladimir
                  • Joerg Hansmann
                    Hi Vladimir, ... From: Vladimir.K To: Sent: Monday, September 03, 2001 11:08 AM Subject: [buildcheapeeg]
                    Message 9 of 13 , Sep 3, 2001
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                      Hi Vladimir,

                      ----- Original Message -----
                      From: Vladimir.K <gogol101@...>
                      To: <buildcheapeeg@yahoogroups.com>
                      Sent: Monday, September 03, 2001 11:08 AM
                      Subject: [buildcheapeeg] Re: Alpha/Theta feedback


                      ...
                      > There is illustrative pictures of electrode placement:
                      >
                      > http://faculty.washington.edu/chudler/1020.html
                      >
                      > I hope, this will help you.

                      Thanks. This picture is much more informative than my old one.

                      > By the way, what variant of analog part EEG are you using ?

                      It is the old gameportEEG input stage. Execpt for the higher
                      supply voltage and other OPamp types after the INA114 stage,
                      it is essentially the same analog part as in RS232EEG01.
                      However there could be made some improvements regarding
                      to limiting the the amplifier output voltage to the comADC input
                      range.


                      I have made a schematic that shows how to connect
                      the gamportEEG analog part with comADC02 to get a
                      comEEG.
                      (will be uploaded on my web-site at www.jhansmann.de )

                      The pcb layout is not complete. However I assume, that
                      the one channel comEEG can be built on
                      a single sided half euro-size pcb (100mm x 80mm)

                      > Do you generate tones by PC sound card ?

                      Yes. The waveforms (at the moment simple sine waves, but it could
                      be any waveform) are calculated in real-time and played with some
                      lag (due to DMA-buffer size) via the wave output of the soundcard.
                      Stereo output is supported (could be interesting for generating
                      hemisync signals with the Monroe method)

                      I am using the latest allegro3937 WIP version (multi-platform
                      game-development library for DOS (with DJGPP), WIN9X and DirectX7 or later
                      (with MSVC or MINGW32 - compiler), LINUX, BeOS, MAC OS)


                      Regards,

                      Joerg
                    • peterson@discover-net.net
                      Joerg--Glad to hear you are playing with alpha-theta. Yes. A2 (actually Au2) would be the right earlobe. If your other electrode is at Cz I imagine you could
                      Message 10 of 13 , Sep 4, 2001
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                        Joerg--Glad to hear you are playing with alpha-theta. Yes. A2
                        (actually Au2) would be the right earlobe. If your other electrode
                        is at Cz I imagine you could use your left earlobe (Au1) instead if
                        you wanted to, with no particular difference in effect.

                        Many people--I suppose most--are able to produce stronger alpha than
                        theta. You should set the theta threshold separately, not use the
                        same one as for alpha. You will need to experiment to get the right
                        threshold, but it should be one that provides feedback about 25% of
                        the time for theta. Also as you get better at producing either alpha
                        or theta, you can set the threshold for that band up higher. If
                        you're exceeding an alpha threshold of 25 uV 90% of the time, set it
                        up a few microvolts til you're only exceeding threshold 50 or 60% of
                        the time.

                        Also, traditionally, alpha-theta is usually trained at O1, which is
                        on the back of the head. Both the Greens and Peniston use(d) this
                        site. Find a bony bump at the back of your head about 3 or 4 cm from
                        the top of your neck. This bump is called the inion, and is a
                        beginning-point for locating EEG sites. O1 will be about 2.5 cm up
                        and 2.5 cm to the left of that bony protrusion.

                        Actually, though, since you started training at Cz, there is probably
                        no reason to change now. At least one published alpha-theta study
                        used (if I remember correctly) C3 and got perfectly good results, so
                        probably anywhere from Cz back is OK.

                        If you just want to train alpha, Pz is probably the best site, but
                        again Cz would be OK. Since you apparently aren't getting much
                        feedback on theta, you are probably actually doing alpha training in
                        effect.

                        --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
                        > Hi,
                        >
                        > since about 5 days I am using the comEEG prototype for
                        > Alpha/Theta audio-feedback. Electrode positions for
                        > 1 channel are Cz - A2
                        > (A2 should be right ear lobe. Is that right ? My picture with
                        electrode-
                        > positions is a little bit unclear).
                        >
                        > Audio-feedback is given using two sine-wave oscillators (one lower
                        > frequency for Theta and one higher frequency to indicate Alpha)
                        > which amplitudes are controlled by the geometric addition
                        > (root sum of squares) of the FFT output for each frequency band.
                        >
                        > If a (fixed) threshold of 25uV is met, the feedback sound
                        > is played at a low volume. A voltage between 25uV and 50uV increases
                        > the volume and everything above 50uV is played at maximum volume.
                        >
                        > With this setup I have been able to increase Alpha (lying position,
                        eyes
                        > closed), so that the Alpha-feedback sound is played nearly 100% of
                        time.
                        >
                        > However I have no idea how to get significant Theta.
                        >
                        > What am I doing wrong ?
                        > Should I train Alpha with higher thresholds first ?
                        >
                        > And what is the great difference in
                        > inner perception between Alpha and Theta ?
                        >
                        >
                        > Regards,
                        >
                        > Joerg
                      • yaniv_vi@yahoo.com
                        hey peterson i have a question : what jeoirg described in his experience of 5 days of alpha (alpha/theta) nfb , is decresead sense of self and feeling of
                        Message 11 of 13 , Sep 5, 2001
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                          hey peterson
                          i have a question :
                          what jeoirg described in his experience of 5 days of alpha
                          (alpha/theta) nfb , is decresead sense of self and feeling of
                          emptiness .
                          this ar supposed to be very high realizations in buddhist
                          meditations ,really really high!
                          is this common for such a short time in other ppl also ?

                          sincerly yaniv v
                          --- In buildcheapeeg@y..., peterson@d... wrote:
                          > Joerg--Glad to hear you are playing with alpha-theta. Yes. A2
                          > (actually Au2) would be the right earlobe. If your other electrode
                          > is at Cz I imagine you could use your left earlobe (Au1) instead if
                          > you wanted to, with no particular difference in effect.
                          >
                          > Many people--I suppose most--are able to produce stronger alpha
                          than
                          > theta. You should set the theta threshold separately, not use the
                          > same one as for alpha. You will need to experiment to get the
                          right
                          > threshold, but it should be one that provides feedback about 25% of
                          > the time for theta. Also as you get better at producing either
                          alpha
                          > or theta, you can set the threshold for that band up higher. If
                          > you're exceeding an alpha threshold of 25 uV 90% of the time, set
                          it
                          > up a few microvolts til you're only exceeding threshold 50 or 60%
                          of
                          > the time.
                          >
                          > Also, traditionally, alpha-theta is usually trained at O1, which is
                          > on the back of the head. Both the Greens and Peniston use(d) this
                          > site. Find a bony bump at the back of your head about 3 or 4 cm
                          from
                          > the top of your neck. This bump is called the inion, and is a
                          > beginning-point for locating EEG sites. O1 will be about 2.5 cm up
                          > and 2.5 cm to the left of that bony protrusion.
                          >
                          > Actually, though, since you started training at Cz, there is
                          probably
                          > no reason to change now. At least one published alpha-theta study
                          > used (if I remember correctly) C3 and got perfectly good results,
                          so
                          > probably anywhere from Cz back is OK.
                          >
                          > If you just want to train alpha, Pz is probably the best site, but
                          > again Cz would be OK. Since you apparently aren't getting much
                          > feedback on theta, you are probably actually doing alpha training
                          in
                          > effect.
                          >
                          > --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
                          > > Hi,
                          > >
                          > > since about 5 days I am using the comEEG prototype for
                          > > Alpha/Theta audio-feedback. Electrode positions for
                          > > 1 channel are Cz - A2
                          > > (A2 should be right ear lobe. Is that right ? My picture with
                          > electrode-
                          > > positions is a little bit unclear).
                          > >
                          > > Audio-feedback is given using two sine-wave oscillators (one
                          lower
                          > > frequency for Theta and one higher frequency to indicate Alpha)
                          > > which amplitudes are controlled by the geometric addition
                          > > (root sum of squares) of the FFT output for each frequency band.
                          > >
                          > > If a (fixed) threshold of 25uV is met, the feedback sound
                          > > is played at a low volume. A voltage between 25uV and 50uV
                          increases
                          > > the volume and everything above 50uV is played at maximum volume.
                          > >
                          > > With this setup I have been able to increase Alpha (lying
                          position,
                          > eyes
                          > > closed), so that the Alpha-feedback sound is played nearly 100%
                          of
                          > time.
                          > >
                          > > However I have no idea how to get significant Theta.
                          > >
                          > > What am I doing wrong ?
                          > > Should I train Alpha with higher thresholds first ?
                          > >
                          > > And what is the great difference in
                          > > inner perception between Alpha and Theta ?
                          > >
                          > >
                          > > Regards,
                          > >
                          > > Joerg
                        • peterson@discover-net.net
                          Yaniv--I don t know. I think it depends a lot on where one is starting from, in terms of prior meditative experience, etc. --Jim
                          Message 12 of 13 , Sep 6, 2001
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                            Yaniv--I don't know. I think it depends a lot on where one is
                            starting from, in terms of prior meditative experience, etc.
                            --Jim

                            --- In buildcheapeeg@y..., yaniv_vi@y... wrote:
                            > hey peterson
                            > i have a question :
                            > what jeoirg described in his experience of 5 days of alpha
                            > (alpha/theta) nfb , is decresead sense of self and feeling of
                            > emptiness .
                            > this ar supposed to be very high realizations in buddhist
                            > meditations ,really really high!
                            > is this common for such a short time in other ppl also ?
                            >
                            > sincerly yaniv v
                          • Joerg Hansmann
                            Hi, ... From: To: Sent: Wednesday, September 05, 2001 3:34 AM Subject: [buildcheapeeg] Re:
                            Message 13 of 13 , Sep 10, 2001
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                              Hi,

                              ----- Original Message -----
                              From: <peterson@...>
                              To: <buildcheapeeg@yahoogroups.com>
                              Sent: Wednesday, September 05, 2001 3:34 AM
                              Subject: [buildcheapeeg] Re: Alpha/Theta feedback


                              > Joerg--Glad to hear you are playing with alpha-theta. Yes. A2
                              > (actually Au2) would be the right earlobe. If your other electrode
                              > is at Cz I imagine you could use your left earlobe (Au1) instead if
                              > you wanted to, with no particular difference in effect.

                              That would be interesting to verify with a 2 channel device.
                              (ch1:Cz-Au1, ch2:Cz-Au2)

                              I have heard that often Au1 and Au2 are tied together.

                              > Many people--I suppose most--are able to produce stronger alpha than
                              > theta. You should set the theta threshold separately, not use the
                              > same one as for alpha.

                              I have now implemented this feature in the comEEG SW.

                              > You will need to experiment to get the right
                              > threshold, but it should be one that provides feedback about 25% of
                              > the time for theta.

                              How is this threshold adjustment done in professional NFB SW ?
                              At the moment I can only imagine 2 ways to do this:
                              1) manual threshold adjustment by trial and error.
                              2) automatic adjustment at program start: For a defined period (a few minutes)
                              the SW samples EEG-data and calculates the threshold to meet the 25%
                              criterion.

                              > Also as you get better at producing either alpha
                              > or theta, you can set the threshold for that band up higher. If
                              > you're exceeding an alpha threshold of 25 uV 90% of the time, set it
                              > up a few microvolts til you're only exceeding threshold 50 or 60% of
                              > the time.


                              I will do this.

                              With the fixed thresholds my NFB-experiments are getting boring and ineffective.


                              > Also, traditionally, alpha-theta is usually trained at O1, which is
                              > on the back of the head.

                              I could imagine that in lying position O1 is susceptible for
                              artifacts caused by varying pressure (head on cushion) on
                              the electrodes.

                              > Both the Greens and Peniston use(d) this
                              > site. Find a bony bump at the back of your head about 3 or 4 cm from
                              > the top of your neck. This bump is called the inion, and is a
                              > beginning-point for locating EEG sites. O1 will be about 2.5 cm up
                              > and 2.5 cm to the left of that bony protrusion.
                              >
                              > Actually, though, since you started training at Cz, there is probably
                              > no reason to change now. At least one published alpha-theta study
                              > used (if I remember correctly) C3 and got perfectly good results, so
                              > probably anywhere from Cz back is OK.
                              >
                              > If you just want to train alpha, Pz is probably the best site, but
                              > again Cz would be OK. Since you apparently aren't getting much
                              > feedback on theta, you are probably actually doing alpha training in
                              > effect.

                              I do not know, how much Theta I would get with correctly adjusted thresholds.

                              Therefore the next thing I will implement is some session statistics.
                              This seems very important to me for tracking progress and to
                              find the right adjustment for the feedback thresholds.



                              Regards,

                              Joerg
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