OBJECTIVE: Independent component analysis (ICA) can disentangle multi-channel electroencephalogram (EEG) signals into a number of artifacts and brain-related signals. However, the identification and interpretation of independent components is time-consuming and involves subjective decision making. We developed and evaluated a semi-automatic tool designed for clustering independent components from different subjects and/or EEG recordings. METHODS: CORRMAP is an open-source EEGLAB plug-in, based on the correlation of ICA inverse weights, and finds independent components that are similar to a user-defined template. Component similarity is measured using a correlation procedure that selects components that pass a threshold. The threshold can be either user-defined or determined automatically. CORRMAP clustering performance was evaluated by comparing it with the performance of 11 users from different laboratories familiar with ICA. RESULTS: For eye-related artifacts, a very high degree of overlap between users (phi>0.80), and between users and CORRMAP (phi>0.80) was observed. Lower degrees of association were found for heartbeat artifact components, between users (phi<0.70), and between users and CORRMAP (phi<0.65). CONCLUSIONS: These results demonstrate that CORRMAP provides an efficient, convenient and objective way of clustering independent components. SIGNIFICANCE: CORRMAP helps to efficiently use ICA for the removal EEG artifacts.
OBJECTIVE: Independent component analysis (ICA) can disentangle multi-channel electroencephalogram (EEG) signals into a number of artifacts and brain-related signals. However, the identification and interpretation of independent components is time-consuming and involves subjective decision making. We developed and evaluated a semi-automatic tool designed for clustering independent components from different subjects and/or EEG recordings. METHODS: CORRMAP is an open-source EEGLAB plug-in, based on the correlation of ICA inverse weights, and finds independent components that are similar to a user-defined template. Component similarity is measured using a correlation procedure that selects components that pass a threshold. The threshold can be either user-defined or determined automatically. CORRMAP clustering performance was evaluated by comparing it with the performance of 11 users from different laboratories familiar with ICA. RESULTS: For eye-related artifacts, a very high degree of overlap between users (phi>0.80), and between users and CORRMAP (phi>0.80) was observed. Lower degrees of association were found for heartbeat artifact components, between users (phi<0.70), and between users and CORRMAP (phi<0.65). CONCLUSIONS: These results demonstrate that CORRMAP provides an efficient, convenient and objective way of clustering independent components. SIGNIFICANCE: CORRMAP helps to efficiently use ICA for the removal EEG artifacts.
Authors: Marcel Franz; Moritz M Nickel; Alexander Ritter; Wolfgang H R Miltner; Thomas Weiss Journal: J Neurophysiol Date: 2015-02-11 Impact factor: 2.714
Authors: Brenton W McMenamin; Alexander J Shackman; Jeffrey S Maxwell; David R W Bachhuber; Adam M Koppenhaver; Lawrence L Greischar; Richard J Davidson Journal: Neuroimage Date: 2009-10-13 Impact factor: 6.556