Möbius-strip-like columnar functional connections are revealed in somato-sensory receptive field centroids.
Receptive fields of neurons in the forelimb region of areas 3b and 1 of primary somatosensory cortex, in cats and monkeys, were mapped using extracellular recordings obtained sequentially from nearly radial penetrations. Locations of the field centroids indicated the presence of a functional system in which cortical homotypic representations of the limb surfaces are entwined in three-dimensional Möbius-strip-like patterns of synaptic connections. Boundaries of somatosensory receptive field in nested groups irregularly overlie the centroid order, and are interpreted as arising from the superposition of learned connections upon the embryonic order. Since the theory of embryonic synaptic self-organization used to model these results was devised and earlier used to explain findings in primary visual cortex, the present findings suggest the theory may be of general application throughout cortex and may reveal a modular functional synaptic system, which, only in some parts of the cortex, and in some species, is manifest as anatomical ordering into columns.
Department of Psychological Medicine, Faculty of Medicine, The University of Auckland Auckland, New Zealand.
James Joseph
JJ
Wright
iVEC@UWA, University of Western Australia Perth, WA, Australia.
Paul David
PD
Bourke
Department of Biomedical Engineering, The University of North Carolina at Chapel Hill Chapel Hill, NC, USA.
Oleg Vyachesslavovich
OV
Favorov
S1 segregates; cortical column; cortical development; cortical response properties; neuromicrocircuitry; synaptic organization