Analysis of Intracerebral EEG Recordings of Epileptic Spikes: Insights From a Neural Network Model

• Published in: IEEE transactions on biomedical engineering 2009-12, Vol.56 (12), p.2782-2795
• Main Authors: Demont-Guignard, Sophie, Benquet, Pascal, Gerber, Urs, Wendling, Fabrice
• Format: Article
• Language: English
• Subjects: Action Potentials; Bioengineering; Biological system modeling; Brain; Brain - physiopathology; Brain modeling; CA1; Circuits; computational modeling; Computer Science; Computer Simulation; Diagnosis, Computer-Assisted; Diagnosis, Computer-Assisted - methods; Electrodes; Electroencephalography; Electroencephalography - methods; Engineering Sciences; Epilepsy; Epilepsy - diagnosis; Epilepsy - physiopathology; Hippocampus; Humans; Life Sciences; local field potentials (LFPs); Modeling and Simulation; Models, Neurological; Nerve Net; Nerve Net - physiopathology; Neural and Evolutionary Computing; Neural networks; Neurons; population spikes; Shape; Signal and Image processing
• ISSN: 0018-9294; 1558-2531
• DOI: 10.1109/TBME.2009.2028015

The pathophysiological interpretation of EEG signals recorded with depth electrodes [i.e., local field potentials (LFPs)] during interictal (between seizures) or ictal (during seizures) periods is fundamental in the presurgical evaluation of patients with drug-resistant epilepsy. Our objective was to explain specific shape features of interictal spikes in the hippocampus (observed in LFPs) in terms of cell- and network-related parameters of neuronal circuits that generate these events. We developed a neural network model based on ldquominimalrdquo but biologically relevant neuron models interconnected through GABAergic and glutamatergic synapses that reproduce the main physiological features of the CA1 subfield. Simulated LFPs were obtained by solving the forward problem (dipole theory) from networks including a large number (~3000) of cells. Insertion of appropriate parameters allowed the model to simulate events that closely resemble actual epileptic spikes. Moreover, the shape of the early fast component (ldquospikerdquo) and the late slow component (ldquonegative waverdquo) was linked to the relative contribution of glutamatergic and GABAergic synaptic currents in pyramidal cells. In addition, the model provides insights about the sensitivity of electrode localization with respect to recorded tissue volume and about the relationship between the LFP and the intracellular activity of principal cells and interneurons represented in the network.