Colin: Created page with "==Maxfilter== Signal Space Separation (SSS) is a method that utilizes the fundamental properties of electromagnetic fields and harmonic function expansions in separating the m..."

2019-05-24T20:49:05Z

Created page with "==Maxfilter== Signal Space Separation (SSS) is a method that utilizes the fundamental properties of electromagnetic fields and harmonic function expansions in separating the m..."

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==Maxfilter==
Signal Space Separation (SSS) is a method that utilizes the fundamental
properties of electromagnetic fields and harmonic function expansions in
separating the measured MEG data into three components:

b'in': The brain signals originating inside of the sensor array (space S'in').

b'out': External disturbances arising outside of the sensor array (space S'out').

n: Noise and artifacts generated by the sensors and sources of interference located very close to the sensors (space S'T').

[[File:Maxfilter.png|600px]]
===SSS===
The basic Maxwell filtering operation can be regarded as spatial filtering,
because separation of b'in' and b'out' is done on the basis of the spatial patterns
and is independent of time. Spatial separation can suppress only
external interference emanating from space S'out', such as electromagnetic
pollution due to power lines, radio communication, traffic, elevators etc.
External interference can also arise in the patient. For instance, normal
cardiac and muscular activation cause fields detectable by MEG sensors,
and any pieces of magnetized material in/on the body may cause very
large disturbances.

===tSSS===
Identification and suppression of the S'T'-space components require additional
knowledge of the temporal dynamics. The temporal extension of
the SSS method (tSSS) significantly widens the software shielding capability
of MaxFilter, because tSSS can suppress also internal interference
that arises in the S'T'-space or very close to it. Such disturbances can be
caused, for example, by magnetized pieces in/on the subject's head (such
as dental work, braces, or magnetized left-overs in burr-holes), or by pacemakers
or stimulators attached to the patient.

Reference: [http://imaging.mrc-cbu.cam.ac.uk/meg/Maxfilter_V2.2?action=AttachFile&do=get&target=Maxfilter_Manual_v2pt2.pdf MaxFilter Manual]

==SSP==

EOG Type : 202 ac1.info.chs.kind - Eye Blink
<br>ECG Type : 402 ac1.info.chs.kind - Heart Beat

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Colin: Created page with "==Maxfilter== Signal Space Separation (SSS) is a method that utilizes the fundamental properties of electromagnetic fields and harmonic function expansions in separating the m..."