<s>
Quantitative	B-Algorithm
electroencephalography	I-Algorithm
(	O
qEEG	B-Algorithm
or	O
QEEG	B-Algorithm
)	O
is	O
a	O
field	O
concerned	O
with	O
the	O
numerical	O
analysis	O
of	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
data	O
and	O
associated	O
behavioral	O
correlates	O
.	O
</s>
<s>
Techniques	O
used	O
in	O
digital	O
signal	O
analysis	O
are	O
extended	O
to	O
the	O
analysis	O
of	O
electroencephalography	B-Application
(	O
EEG	B-Application
)	O
.	O
</s>
<s>
These	O
include	O
wavelet	B-Algorithm
analysis	O
and	O
Fourier	B-Algorithm
analysis	O
,	O
with	O
new	O
focus	O
on	O
shared	O
activity	O
between	O
rhythms	O
including	O
phase	O
synchrony	O
(	O
coherence	O
,	O
phase	O
lag	O
)	O
and	O
magnitude	O
synchrony	O
(	O
comodulation/correlation	O
,	O
and	O
asymmetry	O
)	O
.	O
</s>
<s>
The	O
analog	O
signal	O
comprises	O
a	O
microvoltage	O
time	O
series	O
of	O
the	O
EEG	B-Application
,	O
sampled	O
digitally	O
and	O
sampling	O
rates	O
adequate	O
to	O
over-sample	O
the	O
signal	O
(	O
using	O
the	O
Nyquist	O
principle	O
of	O
exceeding	O
twice	O
the	O
highest	O
frequency	O
being	O
detected	O
)	O
.	O
</s>
<s>
Modern	O
EEG	B-Application
amplifiers	O
use	O
adequate	O
sampling	O
to	O
resolve	O
the	O
EEG	B-Application
across	O
the	O
traditional	O
medical	O
band	O
from	O
DC	O
to	O
70	O
or	O
100Hz	O
,	O
using	O
sample	O
rates	O
of	O
250/256	O
,	O
500/512	O
,	O
to	O
over	O
1000	O
samples	O
per	O
second	O
,	O
depending	O
on	O
the	O
intended	O
application	O
.	O
</s>
<s>
QEEG	B-Algorithm
can	O
be	O
performed	O
by	O
open-source	O
toolboxes	O
such	O
as	O
EEGLAB	B-Algorithm
or	O
the	O
Neurophysiological	O
Biomarker	O
Toolbox	O
.	O
</s>
<s>
Several	O
QEEG	B-Algorithm
products	O
have	O
received	O
Class	O
2	O
FDA	O
medical	O
device	O
clearance	O
and	O
the	O
method	O
has	O
received	O
some	O
medical	O
acceptance	O
for	O
use	O
in	O
epilepsy	O
patients	O
.	O
</s>
<s>
However	O
QEEG	B-Algorithm
has	O
not	O
been	O
endorsed	O
by	O
the	O
American	O
Academy	O
of	O
Neurology	O
or	O
the	O
American	O
Clinical	O
Neurophysiology	O
Society	O
.	O
</s>
<s>
The	O
Fourier	B-Algorithm
decomposes	O
the	O
EEG	B-Application
time	O
series	O
into	O
a	O
voltage	O
by	O
frequency	O
spectral	O
graph	O
commonly	O
called	O
the	O
"	O
power	O
spectrum	O
"	O
,	O
with	O
power	O
being	O
the	O
square	O
of	O
the	O
EEG	B-Application
magnitude	O
,	O
and	O
magnitude	O
being	O
the	O
integral	O
average	O
of	O
the	O
amplitude	O
of	O
the	O
EEG	B-Application
signal	O
,	O
measured	O
from( +	O
)	O
peak-to-(- )	O
peak	O
)	O
,	O
across	O
the	O
time	O
sampled	O
,	O
or	O
epoch	O
.	O
</s>
<s>
The	O
epoch	O
length	O
determines	O
the	O
frequency	O
resolution	O
of	O
the	O
Fourier	B-Algorithm
,	O
with	O
a	O
1-second	O
epoch	O
providing	O
a	O
1Hz	O
resolution	O
(	O
plus/minus	O
0.5Hz	O
resolution	O
)	O
,	O
and	O
a	O
4-second	O
epoch	O
providing	O
¼	O
Hz	O
,	O
or	O
plus/minus	O
0.125Hz	O
resolution	O
.	O
</s>
<s>
A	O
wavelet	B-Algorithm
is	O
a	O
time-frequency	O
transformation	O
that	O
allows	O
analysis	O
of	O
EEG	B-Application
signals	O
in	O
the	O
time	O
extension	O
that	O
is	O
not	O
possible	O
with	O
Fourier	B-Algorithm
analysis	O
.	O
</s>
<s>
QEEG	B-Algorithm
has	O
been	O
accepted	O
for	O
diagnostic	O
evaluation	O
in	O
some	O
areas	O
,	O
such	O
as	O
cerebro-vascular	O
disorders	O
,	O
encephalopathy	O
,	O
dementia	O
and	O
epilepsy	O
,	O
though	O
it	O
remains	O
yet	O
to	O
be	O
accepted	O
in	O
other	O
clinical	O
areas	O
,	O
such	O
as	O
diagnosing	O
mild	O
traumatic	O
brain	O
injury	O
or	O
psychiatric	O
disorders	O
.	O
</s>
<s>
The	O
use	O
of	O
qEEG	B-Algorithm
techniques	O
in	O
investigations	O
in	O
clinical	O
and	O
research	O
settings	O
are	O
ongoing	O
.	O
</s>
<s>
QEEG	B-Algorithm
has	O
also	O
been	O
utilized	O
to	O
provide	O
neurofeedback	B-Application
,	O
which	O
is	O
a	O
form	O
of	O
biofeedback	O
,	O
wherein	O
electrical	O
activity	O
in	O
the	O
brain	O
is	O
monitored	O
by	O
a	O
computer	O
program	O
,	O
which	O
is	O
applied	O
to	O
modulate	O
visual	O
or	O
auditory	O
stimuli	O
-	O
These	O
stimuli	O
,	O
in	O
turn	O
,	O
are	O
designed	O
to	O
be	O
controlled	O
by	O
the	O
user	O
.	O
</s>
