title: Neuronal substrates of sensory gating within the human brain.
abstract: BACKGROUND
  For the human brain, habituation to irrelevant sensory input is an important function whose failure is associated with behavioral disturbances. Sensory gating can be studied by recording the brain's electrical responses to repeated clicks: the P50 potential is normally reduced to the second of two paired clicks but not in schizophrenia patients. To identify its neural correlates, we recorded electrical traces of sensory gating directly from the human hippocampus and neocortex.
  
  
  METHODS
  Intracranial evoked potentials were recorded using hippocampal depth electrodes and subdural strip and grid electrodes in 32 epilepsy patients undergoing invasive presurgical evaluation.
  
  
  RESULTS
  We found evidence of sensory gating only in the hippocampus, the temporo-parietal region (Brodmann's areas 22 and 2), and the prefrontal cortex (Brodmann's areas 6 and 24); however, whereas neocortical habituating responses to paired clicks were peaking around 50 msec, responses within the hippocampus proper had a latency of about 250 msec.
  
  
  CONCLUSIONS
  Consistent with data from animal studies, our findings show that the hippocampus proper contributes to sensory gating, albeit during a time window following neocortical habituation processes. Thus, sensory gating may be a multistep process, with an early phase subserved by the temporo-parietal and prefrontal cortex and a later phase mediated by the hippocampus.
authors.affiliation: Department of Epileptology, University of Bonn, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Grunwald
authors.forename: Nashaat N
authors.initials: NN
authors.lastname: Boutros
authors.forename: Nico
authors.initials: N
authors.lastname: Pezer
authors.forename: Joachim
authors.initials: J
authors.lastname: von Oertzen
authors.forename: Guillen
authors.initials: G
authors.lastname: Fernández
authors.forename: Carlo
authors.initials: C
authors.lastname: Schaller
authors.forename: Christian E
authors.initials: CE
authors.lastname: Elger
mesh_terms: D000328:Adult; D001921:Brain / Q000033:anatomy & histology* / Q000503:physiopathology*; D005071:Evoked Potentials / Q000502:physiology; D005260:Female; D006185:Habituation, Psychophysiologic / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D009474:Neurons / Q000502:physiology; D011930:Reaction Time; D012559:Schizophrenia / Q000503:physiopathology*; D012679:Sense Organs