title: Burst firing of single neurons in the human medial temporal lobe changes before epileptic seizures.
abstract: To better understand the mechanisms that lead to the sudden and unexpected occurrence of seizures, with the neuronal correlate being abnormally synchronous discharges that disrupt neuronal function.
  
  
  
  To address this problem, we recorded single neuron activity in epilepsy patients during the transition to seizures to uncover specific changes of neuronal firing patterns. We focused particularly on neurons repeatedly firing discrete groups of high-frequency action potentials (so called bursters) that have been associated with ictogenesis. We analyzed a total of 459 single neurons and used the mean autocorrelation time as a quantitative measure of burstiness. To unravel the intricate roles of excitation and inhibition, we also examined differential contributions from putative principal cells and interneurons.
  
  
  
  During interictal recordings, burstiness was significantly higher in the seizure onset hemisphere, an effect found only for principal cells, but not for interneurons, and which disappeared before seizures.
  
  
  
  These findings deviate from conventional views of ictogenesis that propose slowly-increasing aggregates of bursting neurons which give rise to seizures once they reach a critical mass.
  
  
  
  Instead our results are in line with recent hypotheses that bursting may represent a protective mechanism by preventing direct transmission of postsynaptic high-frequency oscillations.
authors: Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany.
authors: Heidemarie
authors: H
authors: Gast
authors: Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany.
authors: Johannes
authors: J
authors: Niediek
authors: Department of Neurology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
authors: Kaspar
authors: K
authors: Schindler
authors: Stereotaxy and MR-Based OR Techniques, Department of Neurosurgery, University of Bonn, Bonn, Germany.
authors: Jan
authors: J
authors: Boström
authors: Stereotaxy and MR-Based OR Techniques, Department of Neurosurgery, University of Bonn, Bonn, Germany.
authors: Volker A
authors: VA
authors: Coenen
authors: Laboratory for Experimental Epileptology and Cognition Research, Department of Epileptology, University of Bonn, Bonn, Germany.
authors: Heinz
authors: H
authors: Beck
authors: Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany.
authors: Christian E
authors: CE
authors: Elger
authors: Cognitive and Clinical Neurophysiology, Department of Epileptology, University of Bonn, Bonn, Germany. Electronic address: florian.mormann@ukb.uni-bonn.de.
authors: Florian
authors: F
authors: Mormann
mesh_terms: D000200:Action Potentials; D000328:Adult; D016022:Case-Control Studies; D004827:Epilepsy / Q000503:physiopathology*; D019706:Excitatory Postsynaptic Potentials; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009474:Neurons / Q000502:physiology*; D013702:Temporal Lobe / Q000503:physiopathology*
keywords: Burstiness; Interictal; Interneurons; Pre-ictal; Principal cells