Implications of synaptic digitisation and error for neocortical function
Recent work in hippocampus suggests that correlation-based synaptic strengthening occurs both imprecisely and digitally. We explore this in a model in which synapses are created according to a fitness function and are occasionally incorrectly placed. Synapses spread beyond the high fitness (wm) area to lower fitness (wp) areas to an extent that depends on the error rate and the fitness ratio wm/wp. This limits the accuracy of connections and thus the size of neural networks. We suggest that in neocortex layer 6 cells measure wm/wp and control the plasticity of thalamic relay cells via their burst/tonic transition. If errors do occur despite this mechanism, they can act as seeds for new learning. This in turn requires offline rewiring of layer 6 connections by processes that resemble REM and slow-wave sleep.
neural networks neocortex sleep plasticity regulation synaptic error