<s>
Cordance	B-Algorithm
,	O
a	O
measure	O
of	O
brain	B-Application
activity	I-Application
,	O
is	O
a	O
quantitative	B-Algorithm
electroencephalographic	I-Algorithm
(	O
QEEG	B-Algorithm
)	O
method	O
,	O
developed	O
in	O
Los	O
Angeles	O
in	O
the	O
1990s	O
.	O
</s>
<s>
It	O
combines	O
complementary	O
information	O
from	O
absolute	O
(	O
the	O
amount	O
of	O
power	O
in	O
a	O
frequency	O
band	O
at	O
a	O
given	O
electrode	O
)	O
and	O
relative	O
power	O
(	O
the	O
percentage	O
of	O
power	O
contained	O
in	O
a	O
frequency	O
band	O
relative	O
to	O
the	O
total	O
spectrum	O
)	O
of	O
EEG	B-Application
spectra	O
.	O
</s>
<s>
Cordance	B-Algorithm
is	O
a	O
measure	O
of	O
regional	O
brain	B-Application
activity	I-Application
,	O
computed	O
using	O
QEEG	B-Algorithm
measures	O
of	O
brain	O
wave	O
patterns	O
in	O
an	O
algorithm	O
developed	O
at	O
the	O
by	O
Drs	O
.	O
</s>
<s>
The	O
cordance	B-Algorithm
algorithm	O
includes	O
steps	O
of	O
(	O
a	O
)	O
reattribution	O
of	O
EEG	B-Application
power	O
,	O
(	O
b	O
)	O
spatial	O
normalization	O
of	O
absolute	O
and	O
relative	O
power	O
,	O
and	O
(	O
c	O
)	O
combination	O
of	O
the	O
transformed	O
absolute	O
and	O
transformed	O
relative	O
power	O
to	O
yield	O
the	O
cordance	B-Algorithm
values	O
themselves	O
.	O
</s>
<s>
In	O
comparison	O
with	O
other	O
QEEG	B-Algorithm
measures	O
,	O
such	O
as	O
absolute	O
power	O
or	O
relative	O
power	O
,	O
cordance	B-Algorithm
appears	O
to	O
have	O
a	O
superior	O
correlation	O
with	O
regional	O
brain	O
perfusion	O
,	O
one	O
of	O
the	O
other	O
standard	O
measures	O
of	O
regional	O
brain	B-Application
activity	I-Application
.	O
</s>
<s>
Because	O
cordance	B-Algorithm
is	O
derived	O
from	O
EEG	B-Application
signals	O
,	O
assessments	O
of	O
brain	O
function	O
with	O
cordance	B-Algorithm
do	O
not	O
require	O
the	O
use	O
of	O
radioactive	O
tracer	O
molecules	O
,	O
as	O
is	O
the	O
case	O
with	O
some	O
other	O
functional	B-Algorithm
neuroimaging	I-Algorithm
methods	O
(	O
PET	B-Application
or	O
SPECT	O
scanning	O
)	O
.	O
</s>
<s>
Cordance	B-Algorithm
has	O
been	O
applied	O
to	O
studying	O
brain	B-Application
activity	I-Application
in	O
a	O
variety	O
of	O
neurological	O
and	O
psychiatric	O
disorders	O
.	O
</s>
