Spiral Waves in Disinhibited Mammalian Neocortex #MMPMID15525774
Huang X; Troy WC; Yang Q; Ma H; Laing CR; Schiff SJ; Wu JY
J Neurosci 2004[Nov]; 24 (44): 9897-902 PMID15525774show ga
Spiral waves are a basic feature of excitable systems. Although such waves have been observed in a variety of biological systems, they have not been observed in the mammalian cortex during neuronal activity. Here, we report stable rotating spiral waves in rat neocortical slices visualized by voltage-sensitive dye imaging. Tissue from the occipital cortex (visual) was sectioned parallel to cortical lamina to preserve horizontal connections in layers III-V (500-?m-thick, ?4 × 6 mm2). In such tangential slices, excitation waves propagated in two dimensions during cholinergic oscillations. Spiral waves occurred spontaneously and alternated with plane, ring, and irregular waves. The rotation rate of the spirals was ?10 turns per second, and the rotation was linked to the oscillations in a one-cycle- one-rotation manner. A small (<128 ?m) phase singularity occurred at the center of the spirals, about which were observed oscillations of widely distributed phases. The phase singularity drifted slowly across the tissue (?1 mm/10 turns). We introduced a computational model of a cortical layer that predicted and replicated many of the features of our experimental findings. We speculate that rotating spiral waves may provide a spatial framework to organize cortical oscillations.
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J+Neurosci 2004 ; 24 (44): 9897-902
