Some dynamics arising from learning in a hippocampal model

Summary form only given. In our simulations of hippocampal region CA3, we have observed a variety of dynamical behaviors over the course of learning. Such dynamics can either help or hurt the model as it is being trained to learn a cognitive task that depends on normal hippocampal function. The parameterization of the time spanning, associative synaptic modification rule has been investigated. In particular there is an interaction between the time constant of the NMDA-receptor and input longevity that has a direct effect on the dynamics of the neuronal codes that form. Inhibition potently affects the dynamics of cell firing, and it is easy to lose activity control when the excitatory synapses between primary, excitatory neurons alone are being modified. Synaptic modification of either the input or output synapses of an inhibitory neuron can, to a greater or lesser extent, compensate for synaptic modifications between primary neurons.