Throughout the development of the map of orientation preference in primary visual cortex (V1), the statistics and strength of afferent inputs, synaptic strengths and sizes, and lateral connection patterns are all changing. It is therefore surprising that despite these massive changes, the orientation map develops with a remarkable stability in both orientation preference and orientation domain size (Chapman et al., 1996). It has been proposed that homeostatic mechanisms that automatically adjust the intrinsic excitability of neurons and/or multiplicatively scale synaptic strengths allow individual neurons to maintain stability of overall activity levels (Desai, 2003, Turrigiano and Nelson, 2004). We have explored the possibility that homeostatic plasticity also underlies the stability of map organization. Several homeostatic rules have been used to replace ad-hoc methods in simple self organizing map (SOM) models (e.g. Butko and Triesch, 2007, Sullivan and de Sa, 2006). However it still remains to be seen whether these rules will be sufficient in a more realistic model that includes adapting lateral connections. We propose a model that includes both homeostatic plasticity of intrinsic excitability and scaling of lateral connection strengths. In this way, a balance between activation due to afferent and lateral connection types is maintained. This model is the first to reproduce experimentally observed orientation map organization, selectivity , and stability despite changes in the input statistics.
|Publication status||Published - 2007|
|Event||Society for Neuroscience Annual Meeting, 2007 - San Diego, California, United States|
Duration: 3 Nov 2007 → 7 Nov 2007
|Conference||Society for Neuroscience Annual Meeting, 2007|
|City||San Diego, California|
|Period||3/11/07 → 7/11/07|