Source stability index: a novel beamforming based localisation metric

TY - JOUR

T1 - Source stability index

T2 - a novel beamforming based localisation metric

AU - Hymers, Mark

AU - Prendergast, Garreth

AU - Johnson, Sam R.

AU - Green, Gary G. R.

PY - 2010/1/15

Y1 - 2010/1/15

N2 - Many experimental studies into human brain function now use magnetoencephalography (MEG) to non-invasively investigate human neuronal activity. A number of different analysis techniques use the observed magnetic fields outside of the head to estimate the location and strength of the underlying neural generators. One such technique, a spatial filtering method known as Beamforming, produces whole-head volumetric images of activation. Typically, a differential power map throughout the head is generated between a time window containing the response to a stimulus of interest and a window containing background brain activity. A statistical test is normally performed to reveal locations which show a significantly different response in the presence of the stimulus. Despite this being a widely used measure, for both phase-locked and non-phase-locked information, it requires a number of assumptions: namely that the baseline activity defined is stable and also that a change in total power is the most effective way of revealing the neuronal Sources required for the task. This paper introduces a metric which evaluates the consistency of the response at each location within a cortical Volume. Such a method of localisation negates the need for a baseline period of activity to be defined and also moves away from simply considering the energy content of brain activity. The paper presents both simulated and real data. It demonstrates that this new metric of stability is able to more accurately and, crucially, more reliably draw inferences about neuronal sources of interest. (C) 2009 Elsevier Inc. All rights reserved.

AB - Many experimental studies into human brain function now use magnetoencephalography (MEG) to non-invasively investigate human neuronal activity. A number of different analysis techniques use the observed magnetic fields outside of the head to estimate the location and strength of the underlying neural generators. One such technique, a spatial filtering method known as Beamforming, produces whole-head volumetric images of activation. Typically, a differential power map throughout the head is generated between a time window containing the response to a stimulus of interest and a window containing background brain activity. A statistical test is normally performed to reveal locations which show a significantly different response in the presence of the stimulus. Despite this being a widely used measure, for both phase-locked and non-phase-locked information, it requires a number of assumptions: namely that the baseline activity defined is stable and also that a change in total power is the most effective way of revealing the neuronal Sources required for the task. This paper introduces a metric which evaluates the consistency of the response at each location within a cortical Volume. Such a method of localisation negates the need for a baseline period of activity to be defined and also moves away from simply considering the energy content of brain activity. The paper presents both simulated and real data. It demonstrates that this new metric of stability is able to more accurately and, crucially, more reliably draw inferences about neuronal sources of interest. (C) 2009 Elsevier Inc. All rights reserved.

KW - STEADY-STATE RESPONSES

KW - CORTICAL ACTIVITY

KW - MEG

KW - MODEL

KW - MAGNETOENCEPHALOGRAPHY

KW - RECONSTRUCTION

KW - DYNAMICS

KW - BRAIN

KW - AREAS

UR - http://www.scopus.com/inward/record.url?scp=70749129858&partnerID=8YFLogxK

U2 - 10.1016/j.neuroimage.2009.09.055

DO - 10.1016/j.neuroimage.2009.09.055

M3 - Article

SN - 1053-8119

VL - 49

SP - 1385

EP - 1397

JO - Neuroimage

JF - Neuroimage

IS - 2

ER -