Electrophysiological Methods for the Study of
the Nervous- and Muscular-systems
György Karmos, Balázs Dombovári
István Ulbert
Péter Pázmány Catholic University
Faculty of Information Technology
Budapest, Hungary
[karmos, dombovari]@itk.ppke.hu, ulbert@itk.ppke.hu
Richárd Csercsa, Richárd Fiáth,
Domonkos Horváth
Institute for Psychology of the
Hungarian Academy of Sciences
Budapest, Hungary
[csercsa,fiath]@cogpsyphy.hu,
horvath_doma@yahoo.co.uk
The course makes the students familiar
with the topics of electrophysiology, the major
recording techniques, and the relationships
among the fields of bioelectromagnetism.
They get acquainted with electrophysiological
techniques and devices used in neuroscience
and in every day’s clinical practice. The great
advantage of the electrophysiological methods
is that we can study nervous and muscle func-
tion in intact organisms or with minimal dam-
age of the functioning tissue. Electrophysiolo-
gy is a broad area of biosciences. In the course
we deal only the bioelectric processes of the
nervous and muscle systems since they are
most interesting from the point of information
technology.
The first lectures basic bioelectrical phe-
nomena of nerve cells are discussed. When a
nerve impulse travels along a nerve fiber ac-
tion potential can be recorded. This bioelectric
phenomenon is a concomitant of the biological
process of the nerve conduction however at the
same time the potential changes play active
role in the spread of the excitation. This dual
nature of bioelectricity is strongly emphasized.
Connection between the living tissue and
the recording apparatuses is realized by the
electrodes. In this interface connection is
formed between electron conductor and elec-
trolyte conductor. Ideal electrode does not
exist living tissue is a chemically aggressive
medium for electrodes: there is always a
chemical reaction between the electrode and
the tissue. Critical problem of electrophysio-
logical electrodes are the electrode stability
and biocompatibility: on the one hand, elec-
trodes have to withstand the chemically ag-
gressive living tissue, on the other hand, elec-
trode-caused harm to the living tissue has to
minimized. Chronically implanted electrodes
of different type pacemakers must operate for
decades.
Recording techniques of neuroelectric sig-
nals can be categorized form the membrane
potential of the single neuron recorded by in-
tracellular microelectrodes to the electroen-
cephalographic activity (EEG) of the brain
recorded by macroelectrodes on the scalp sur-
face. Lectures of the course offer detailed sur-
vey of in vitro and in vivo methods. Extracel-
lular single unit recording technique earlier
was regarded as a purely research method
nowadays it is applied in human brain com-
puter interfaces. Computer based multichannel
EEG recording makes possible the mapping of
brain processes with good time resolution and
application of complex mathematical signal
processing methods offers possibility the
forewarning of epileptic seizures. Beyond the
electrical activity noninvasive recording of the
magnetic signals produced by the brain serves
also as a diagnostic tool. Good spatial resolu-
tion of magnetoencephalography makes it a
good complement of EEG.
Surface recorded brain oscillations time
locked to sensory stimuli – called event related
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potentials (ERP) – became essential in study-
ing perceptional and other psychological phe-
nomena and serve as one of the a basic tools of
cognitive psychophysiology. Recording of
early components of ERPs can be used as di-
agnostic method to reveal pathology of senso-
ry pathways even in unconscious patients e.g.
the objective audiometry using the brainstem
auditory evoked potentials. One of the lectures
of the course deals with the different forms of
the ERPs.
Recording of the bioelectrical activity of
striated muscles can be used for diagnosing of
pathology of the motor part of the nervous
system as well as the muscles themselves. In
the clinical practice needle electrodes are used
for the localization of pathological changes.
Surface electrodes are applied in psychological
research as well as in sport- and work-
physiology to analyze optimal performance of
muscles. The lecture dealing with electromy-
ography describes both of these techniques
and applications.
Computer methods become more and more
important in analyzing bioelectrical signals. In
the last lecture of the course we give an over-
view of the mathematical methods that are
used for electrophysiological signal pro-
cessing.
Understanding of brain functions and pa-
thology needs collaboration of researchers of
different disciplines. Information technology
and bioengineering fields gain more and more
importance both in neuroscience and in the
related clinical areas. At the same time bio
inspired solutions become essential in man-
made systems. In preparing the material of the
present course we intended to give and over-
view of electrophysiological methods that may
be useful for students with engineering as well
as biological interest.
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