Pawel Kudela, Piotr J. Franaszczuk, Gregory K. Bergey
Department of Neurology, Johns Hopkins University School of Medicine and Epilepsy Center, Johns Hopkins Hospital , Baltimore, Maryland U.S.A.
RATIONALE: Both excitation and inhibition in neural networks play important roles in the generation and propagation of epileptiform activity. The objective of this study was to evaluate the role of decreasing inhibition in promoting increased synchronous activity in neural networks.
METHODS: The model consists of locally connected neurons simulated using the modified Av-Ron/Rinzel model. There are both inhibitory and excitatory neurons synaptically connected. Each neuron has synaptic input from randomly chosen excitatory and inhibitory neurons. The number of excitatory connections is constant whereas the number of inhibitory connections is reduced during simulations. The network is constantly activated by random excitatory input.
RESULTS: When excitatory and inhibitory inputs were nearly equal, simulation of the network produced only relatively short (<5 action potentials) and irregular bursts of activity. When the number of active inhibitory connections is decreased the bursts become progressively longer and more synchronized.
CONCLUSIONS: Decreasing the ratio of inhibitory to excitatory connections in networks of locally connected neurons produces patterns of increasingly synchronous and longer bursts. This behavior mirrors experiments in dissociated neurons following addition of tetanus toxin.
(Supported by the Epilepsy Foundation , NIH NS 38958-01,and NIH NS 33732-01)
Epilepsia Vol. 40, (Suppl. 7): 12, 1999