Coherence and phase locking in the scalp EEG and between LORETA model sources, and microstates as putative mechanisms of brain temporo-spatial functional organization

Lehmann, Dietrich; Faber, Pascal L; Gianotti, Lorena; Kochi, Kieko; Pascual-Marqui, Roberto D (2006). Coherence and phase locking in the scalp EEG and between LORETA model sources, and microstates as putative mechanisms of brain temporo-spatial functional organization. Journal of physiology Paris, 99(1), pp. 29-36. Elsevier 10.1016/j.jphysparis.2005.06.005

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Brain electric mechanisms of temporary, functional binding between brain regions are studied using computation of scalp EEG coherence and phase locking, sensitive to time differences of few milliseconds. However, such results if computed from scalp data are ambiguous since electric sources are spatially oriented. Non-ambiguous results can be obtained using calculated time series of strength of intracerebral model sources. This is illustrated applying LORETA modeling to EEG during resting and meditation. During meditation, time series of LORETA model sources revealed a tendency to decreased left-right intracerebral coherence in the delta band, and to increased anterior-posterior intracerebral coherence in the theta band. An alternate conceptualization of functional binding is based on the observation that brain electric activity is discontinuous, i.e., that it occurs in chunks of up to about 100 ms duration that are detectable as quasi-stable scalp field configurations of brain electric activity, called microstates. Their functional significance is illustrated in spontaneous and event-related paradigms, where microstates associated with imagery- versus abstract-type mentation, or while reading positive versus negative emotion words showed clearly different regions of cortical activation in LORETA tomography. These data support the concept that complete brain functions of higher order such as a momentary thought might be incorporated in temporal chunks of processing in the range of tens to about 100 ms as quasi-stable brain states; during these time windows, subprocesses would be accepted as members of the ongoing chunk of processing.

Item Type:	Journal Article (Original Article)
Division/Institute:	07 Faculty of Human Sciences > Institute of Psychology > Social Neuroscience and Social Psychology
UniBE Contributor:	Gianotti, Lorena
Subjects:	100 Philosophy > 150 Psychology
ISSN:	0928-4257
Publisher:	Elsevier
Language:	English
Submitter:	Lorena Gianotti
Date Deposited:	24 Dec 2014 08:24
Last Modified:	05 Dec 2022 14:38
Publisher DOI:	10.1016/j.jphysparis.2005.06.005
PubMed ID:	16054348
Uncontrolled Keywords:	Binding, Coherence, Phase locking, Microstates, LORETA, EEG, ERP
URI:	https://boris.unibe.ch/id/eprint/61186