title: On the dynamics of cortical development: synchrony and synaptic self-organization.
abstract: We describe a model for cortical development that resolves long-standing difficulties of earlier models. It is proposed that, during embryonic development, synchronous firing of neurons and their competition for limited metabolic resources leads to selection of an array of neurons with ultra-small-world characteristics. Consequently, in the visual cortex, macrocolumns linked by superficial patchy connections emerge in anatomically realistic patterns, with an ante-natal arrangement which projects signals from the surrounding cortex onto each macrocolumn in a form analogous to the projection of a Euclidean plane onto a Möbius strip. This configuration reproduces typical cortical response maps, and simulations of signal flow explain cortical responses to moving lines as functions of stimulus velocity, length, and orientation. With the introduction of direct visual inputs, under the operation of Hebbian learning, development of mature selective response "tuning" to stimuli of given orientation, spatial frequency, and temporal frequency would then take place, overwriting the earlier ante-natal configuration. The model is provisionally extended to hierarchical interactions of the visual cortex with higher centers, and a general principle for cortical processing of spatio-temporal images is sketched.
authors.affiliation: Department of Psychological Medicine, Faculty of Medicine, The University of Auckland Auckland, New Zealand ; Liggins Institute, The University of Auckland Auckland, New Zealand.
authors.forename: James Joseph
authors.initials: JJ
authors.lastname: Wright
authors.forename: Paul David
authors.initials: PD
authors.lastname: Bourke
keywords: cortical development; cortical information flow; cortical response properties; synaptic organization; synchronous oscillation