title: Emergence of complex wave patterns in primate cerebral cortex.
abstract: Slow brain rhythms are attributed to near-simultaneous (synchronous) changes in activity in neuron populations in the brain. Because they are slow and widespread, synchronous rhythms have not been considered crucial for information processing in the waking state. Here we adapted methods from turbulence physics to analyze δ-band (1-4 Hz) rhythms in local field potential (LFP) activity, in multielectrode recordings from cerebral cortex in anesthetized marmoset monkeys. We found that synchrony contributes only a small fraction (less than one-fourth) to the local spatiotemporal structure of δ-band signals. Rather, δ-band activity is dominated by propagating plane waves and spatiotemporal structures, which we call complex waves. Complex waves are manifest at submillimeter spatial scales, and millisecond-range temporal scales. We show that complex waves can be characterized by their relation to phase singularities within local nerve cell networks. We validate the biological relevance of complex waves by showing that nerve cell spike rates are higher in presence of complex waves than in the presence of synchrony and that there are nonrandom patterns of evolution from one type of complex wave to another. We conclude that slow brain rhythms predominantly indicate spatiotemporally organized activity in local nerve cell circuits, not synchronous activity within and across brain regions.
authors: School of Physics, University of Sydney, New South Wales 2006, Australia, ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia.
authors: Rory G
authors: RG
authors: Townsend
authors: ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia, Discipline of Physiology, University of Sydney, Sydney, New South Wales 2006, Australia.
authors: Selina S
authors: http://orcid.org/0000-0003-4227-7924
authors: SS
authors: Solomon
authors: ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia, Discipline of Physiology, University of Sydney, Sydney, New South Wales 2006, Australia.
authors: Spencer C
authors: SC
authors: Chen
authors: ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia, Discipline of Physiology, University of Sydney, Sydney, New South Wales 2006, Australia.
authors: Alexander N J
authors: AN
authors: Pietersen
authors: ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia, Discipline of Physiology, University of Sydney, Sydney, New South Wales 2006, Australia, Save Sight Institute, University of Sydney, Sydney, New South Wales 2001, Australia, and prmartin@sydney.edu.au p.gong@physics.usyd.edu.au.
authors: Paul R
authors: http://orcid.org/0000-0002-5166-9658
authors: PR
authors: Martin
authors: Discipline of Physiology, University of Sydney, Sydney, New South Wales 2006, Australia, Department of Experimental Psychology, University College London, WC1P 0AH, London, United Kingdom.
authors: Samuel G
authors: http://orcid.org/0000-0001-5321-0288
authors: SG
authors: Solomon
authors: School of Physics, University of Sydney, New South Wales 2006, Australia, ARC Centre of Excellence for Integrative Brain Function, University of Sydney, New South Wales 2001, Australia, prmartin@sydney.edu.au p.gong@physics.usyd.edu.au.
authors: Pulin
authors: http://orcid.org/0000-0002-1960-3245
authors: P
authors: Gong
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D002144:Callithrix; D002540:Cerebral Cortex / Q000502:physiology*; D003700:Delta Rhythm / Q000502:physiology*; D004569:Electroencephalography / Q000379:methods; D008297:Male
keywords: cerebral cortex; cortical waves; electroencephalogram; local field potentials