Biomedical Engineering Reference
In-Depth Information
12
(
)
⎡
⎣
+
⎤
⎦
T
−
1
T
WK WK HK
v
=
+
α
(5.38)
v
v
where
W
v
∈
R
3×
is the
v
th diagonal subblock of
W
.
As shown in [1], eLORETA has no localization bias in the presence of measure-
ment noise and biological noise with variance proportional to
W
-1
.
The screenshot in Figure 5.2 shows a practical example for the eLORETA cur-
rent density inverse solution corresponding to a single-subject visual evoked poten-
tial to pictures of flowers. The free academic eLORETA-KEY software and data are
publicly available from the appropriate links at the home page of the KEY Institute
for Brain-Mind Research, University of Zurich (http://www.keyinst.uzh.ch). Maxi-
mum total current density power occurs at about 100 ms after stimulus onset
(shown in panel A). Maximum activation is found in Brodmann areas 17 and 18
(c)
(e)
(a)
(b)
(d)
Figure 5.2
Three-dimensional eLORETA inverse solution displaying estimated current density for a
visual evoked potential to pictures of flowers (single-subject data). (a) Maximum current density
occurs at about 100 ms after stimulus onset. (b) Maximum activation is found in Brodmann areas 17
and 18. (c) Orthogonal slices through the point of maximum activity. (d) Posterior three-dimensional
cortex. (e) Average reference scalp map.
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