Models of activity-dependent neural development

Abstract

Activity-dependent, competitive mechanisms of synaptic plasticity appear to play an important role in many processes of late neural development, where an initially rough connectivity pattern refines to a precise, mature pattern. A prominent example is the formation of ocular dominance columns in the visual cortex of many mammals. These processes may be modeled at several levels. Simple models use abstract neurons and assume synaptic modification according to a hebbian or similar correlation-based rule. These models incorporate biological constraints and attempt to predict large-scale developmental patterns from the combination of synaptic-level plasticity rules and measurable biological patterns of activation and connectivity. More detailed models attempt to incorporate various levels of biophysical realism, including membrane and channel properties and dendritic geometry. Abstract models examine the connectivity patterns that may result if biological development follows certain dynamical or other abstract rules, without concern for how such rules might be implemented at the synapse. The strengths and weaknesses of these approaches are examined through study of models for the development of ocular dominance and of orientation selectivity in the visual cortex.