From: Rob Sacks (editor_at_realization.org)
Date: 2001-05-04 06:17:59
Hi Jim,
> If you could make it put out displays like the original Mind Mirror,
> that might be enough for a beginning, for a first release.
ElectricGuru already does a MindMirror-type display.
(However the magnitudes are weighted differently, so
high frequencies appear to be squashed inward compared
to what they look like on Cade's machine.)
There's now a screenshot showing the MindMirror display
at http://www.realization.org/page/doc0/doc0086.htm.
The illustration shows .5 Hz bands but they can be set
narrower or wider. (As they get narrower, the epoch
gets longer.) The page takes a while to download because
the illustration is large and high-resolution.
I agree about the games and sounds.
> The software might permit the user to define EEG frequency bands
> other than the classic Delta, Theta, Alpha and Beta...
The current version of ElectricGuru does this.
> It would also be neat if you could specify various Boolean
> statements as conditions for feedback. E.g. tone1 if (SMR>x AND
> Theta <y) or maybe symmetry training with a condition like tone1 if
> ABS(rightalpha-leftalpha)<x where tone1 is the specified feedback
> tone.
This is an appealing suggestion because it's probably
the easiest way for me to implement user-programmable
conditions. And it's a lot more elegant than menus. But
I think most users would find it frightening and frustrating
and difficult.
I agree about canned protocols.
> Whether using a canned session or an individually designed one, it
> should be easy to change the numeric values of the thresholds so you
> can easily adjust the difficulty levels during the session.
How about just a single slider for raising or lowering the
difficulty? It would work like this: if you set it at 60,
the software would adjust all the threshholds so you are getting
reward signals on 60 percent of the updates. You could also
choose whether the software should readjust the threshholds
continuously, thus keeping your rewards happening 60 percent
of the time, or whether the adjustment should take place only
when you manually click on "readjust threshholds." This second
option would ensure that the person can sense the improvement
taking place.
>
> One would also want to be able to name and save training protocols
> for future use.
This is already in the current version of ElectricGuru.
> The feedback for any condition might be given whenever the specified
> condition is met or exceeded as averaged across a one-second epoch.
> Two seconds might be workable.
The current version allows you to set the averaging to any
amount of time you want down to the minimum required by
the FFT. I have found that anything shorter than second
is unusable because the reward signals are too erratic and
"jumpy". This has made me extremely skeptical about
the claims being made by some EEG manufacturers about
their super-fast digital filters. If you have to average
the output of those filters over a fairly long time anyway,
what difference does it make how fast they are? I notice
that Lexicor only uses FFT in its software.
> The system should be accurate enough
> so that no more than 5% or so of erroneous feedback is given.
I don't know how to measure this.
> Also, the software should provide the capability of tracking
> amplitudes of the selected bands across the session.
I agree. Excel output (actually, ASCII output which can be
read by Excel) would be easy and flexible.
> Would it be difficult to set the machine up to train coherence? This
> is when your right and left hemispheres not only match in the
> dominant frequency, but are also in phase.
ElectricGuru already does that kind of coherence -- you can
set a threshhold on the number of degrees of phase difference.
(It also does a Pearson correlation.)
However, I have the impression that when people talk
about coherence and synchrony, they don't necessarily
mean this type of algorithm.
One reason why you might want to test in a different
way is to allow for one site to "drive" another.
In such a case, the phase difference might be
large, but it would remain relatively unchanging.
At the time I stopped working on ElectricGuru, I was trying
to find out whether there is any "standard" way of testing
for coherence or synchrony or whatever the official term
may be.
> Now for a truly crazy request. Can it be made to produce coherence
> in two brains at the same time? With electrodes at the
> corrresponding sites on the two heads, say at Cz or at Pz, where
> alpha is often strongest.
ElectricGuru can do that now, provided that the EEG
machine can do it. I would think the BrainMaster could
do it, although perhaps the two people would need to
hold hands to maintain an identical reference voltage.
However, I haven't tried it.
Rob
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