Winter
Brain Conference
Author: Dr. Siegfried Othmer
We are once again at the threshold of
the Winter Brain Conference. Preliminary conferences are already
going on. This year will mark the entry of EEG Support into the
hardware business. With the help of a few gnomes of Zurich we
have developed a QIKtest device that allows us to run a variety
of choice reaction time tests like the CPTs we are used to. Just
working through the development process has been liberating to
our thinking. There has been controversy among users about just
how fast progress in TOVA terms can be made with various techniques.
We’ve been reluctant to subject people to a lot of such tests
because they are such an imposition on people. Now we have a choice.
 The
QIKtest
The new device has nine LED fields in
a 3x3 array, and a left and right button for responding. Auditory
challenges are available as well. Any combination of LEDs can
be used to represent the “go” or “no-go” condition. The tests
can be down-loaded through a serial connection from the clinician’s
computer to the device. The device stores the test results internally,
until they are uploaded to the computer, where the results are
then displayed. The data is then uploadable to the EEG Expert
website for progress tracking over sessions.
Sue has generated a number of one-minute
tests in which the level of difficulty increases as the test progresses.
In fact, it is difficult to believe that the test is only a minute
long. These tests have no direct tie-in to the familiar TOVA or
IVA, but they do give us indication of progress over sessions,
and they are a challenge to the client. Reaction time is tracked,
along with variability and the usual omission and commission errors.
Given the brevity of the test, it is no surprise that we tend
not to register a lot of omission errors. But with the rapidity
of the challenges that have been dialed in, commission errors
are more commonplace than with the TOVA.
The tests are a challenge for adults,
and undoubtedly will overmatch young children. So future tests
will need to accommodate varying ability levels. It is not intended
that these tests be normed. On the contrary, one might envision
a variety of challenges that a person might progress through during
training. Each one will give an additional measure of progress
in training. We have been trying the existing tests in the office,
interspersed with neurofeedback sessions. (Sue used to beat me
in table tennis. Now she routinely bests my reaction time on the
QIKtest. But I am making progress…)
We are also implementing full CPT tests
on the unit. There has to be some pre-testing first before we
commit to a final design that will then be normed. So this is
of necessity a slightly lengthier process. We would like the test
to be close to what people are used to from the TOVA and the IVA,
but we also want to move forward. We will either alter or drop
the 200msec criterion for anticipatory responses because it is
clearly arbitrary and inappropriate. We also intend to handle
the auditory challenges differently.
The auditory TOVA has not caught on very
well, and so potentially significant information is being missed.
I would argue that the auditory TOVA largely differs from the
visual in terms of reaction time and variability, not so much
in terms of omission and commission errors. If that is the case,
then one does not need to complement a visual CPT with a full
auditory CPT. It would be sufficient to do a brief auditory test
to see how much slower the auditory reaction time is, and how
much greater the variability. So for most people the combination
of a visual CPT plus a brief auditory challenge should be sufficient
to characterize them.
We have appealed to the TOVA folks for
lo these many years to give us some additional capabilities, not
to mention getting past the DOS operating system and dot matrix
printers. Since their addition of the auditory test, not much
appears to have happened. So we have finally had to strike out
on our own to solve these problems. One of the features that we
have wanted from TOVA is a time marker to indicate precisely when
the stimulus is being presented. That could then be used to index
a QEEG record, for the subsequent off-line evaluation of evoked
responses. The QIKtest unit includes this feature.
We expect that home users may want the
unit as well, in order to track progress at home, and perhaps
to help establish a good training interval for those who are suffering
cognitive decline.
 Impedance
Meter
Did anyone on the list ever think we
would not only be recommending an impedance meter, but would actually
be building one? Again with the help of the gnomes of Zurich,
we have developed an impedance meter that actually fulfills the
purpose. The problem with conventional impedance meters is that
they are used in a one-time measurement when in fact we are often
contending with wiggly kids whose contact impedance may change
during the session. So an in-line measurement is needed. On the
other hand, incorporating an impedance measurement that does not
impinge on the signal at all is rather a challenge. The solution
is to have an in-line impedance meter that is engaged with a button
push, and that is essentially out of the circuit otherwise. The
unit connects directly to the BrainMaster or NeuroCybernetics
amplifier, and the electrodes are plugged into the impedance meter,
where they remain throughout the session. The meter is simply
“parked” on top of the BrainMaster amp or the NC amp, or next
to a procomp.
The other significant feature of the
impedance meter is that it allows a direct comparison between
the two “legs” of the circuit, the two active leads, with respect
to their contact impedance. This is because what matters almost
more than the impedance itself is the match between the two. Low
contact impedance is one assured way of minimizing the difference
between the two legs, but if we merely guarantee a match, then
our tolerance for contact impedance is relaxed considerably. The
underlying issue is “common-mode rejection,” the ability of the
differential circuit to suppress signals that are common to both
legs. To assure maximum common-mode rejection, both arms or legs
of the circuit should be electrically identical. So, balance is
what matters. The new unit has a display for the balance in resistance
between the two active electrodes, so one can tell at a glance
if a problem exists.
Where this unit comes in handy is whenever
there is a mystery at the beginning of a session as to whether
the signal you are seeing is real. Whenever there is a problem,
or a suspected problem, one generally simply reworks the contacts
to see what difference that makes. Such goings-on may be less
than reassuring to a new client. With the impedance meter installed,
a simple button-push will reveal whether there is a potential
problem, and if there is, which electrode should be worked on
to improve it.
Web-based training
We are also launching the web-based training
at this conference, with the release of Sue’s decision tree. As
an alternative it will also be available on CD. A translation
into Spanish is underway. We expect this offering will be useful
to people who have not attended the advanced training course for
a while, as well as for practitioners of other persuasions who
simply want to gain an acquaintance with our approach. It can
also serve as a refresher to those who have taken the initial
training course in the past couple of years. To be launched shortly
is our Alpha/Theta module.
Attendees at the conference are invited
to a get-together Friday evening where we will meet and discuss
EEG Expert and QIK test assessment.
Dr. Siegfried Othmer
|
