Genetic and epigenetic mechanisms of sensory maps development

One of the central questions of neurobiology is to understand how during development billions of neurons establish synaptic connections, and what are the roles of genes and activity in the formation of specific neuronal circuits . There are two main theoretical models to describe this developmental process . The model of “tabula rasa” implies that initially there is no order in synaptic connections, and that their initial exuberant number undergoes pruning through the competition of neurons for their targets . Alternative model assumes that development of synaptic connections is strictly determined by genes, through signaling molecules that predefine highly ordered connectivity, and that the activity only plays confirmative roles . In the present review, we describe genetic and epigenetic factors involved in the development of sensory maps in barrel cortex and provide evidence that both mechanisms operate in the development of this system . While genetic mechanisms provide course topography of somatosensory map at subcolumnar precision level in its initial state, sensory-driven activity patterns, which are is expressed in barrel cortex during the critical developmental period support competition between sensory inputs (neighbor whiskers) for the cortical territories to achieve columnar level of precision in somatosensory map by the end of the critical period

development, neurons, thalamus, cortex, ion channels, glutamate