ABSTRACT
A model of the thalamocortical system was constructed for the purpose of a computational analysis of low-frequency oscillations that take place in the system. Experimental values were used to guide the parameters used in the model. Both the thalamic reticular and relay nuclei were represented in the model. The thalamic cells were capable of undergoing a low-threshold Ca2+-mediated spike. The values of parameters were varied across the neuronal population in order to ensure that synchrony did not arise due to a false uniformity in the properties of the neurons. Many neurons in the network were not directly connected. The simulation was used to investigate the plausibility and ramifications of certain proposals that have been put forward for the production of synchronous, rhythmic activity in the thalamocortical system. An initial stimulus to the model reticular thalamic layer was found to give rise to rhythmic synchronous activity in the entire system. The production of this activity was found to depend on the presence of connections between the reticular thalamic neurons as well as on the generation of an average inhibitory postsynaptic potential on each reticular thalamic neuron that was similar for all of them. The frequency of thalamic oscillations was found to decrease with increase in the durations of inhibitory postsynaptic potentials as well as the time it took the neurons to rebound once they were released from inhibition. Cortical feedback to the pacemaking reticular thalamic layer was found capable of increasing the amplitude of the oscillations.
