title: Reduced habituation in patients with schizophrenia.
abstract: BACKGROUND
  Neural habituation, the decrease in brain response to repeated stimulation, is a basic form of learning. There is strong evidence for behavioral and physiological habituation deficits in schizophrenia, and one previous study found reduced neural habituation within the hippocampus. However, it is unknown whether neural habituation deficits are specific to faces and limited to the hippocampus. Here we studied habituation of several brain regions in schizophrenia, using both face and object stimuli. Post-scan memory measures were administered to test for a link between hippocampal habituation and memory performance.
  
  
  METHODS
  During an fMRI scan, 23 patients with schizophrenia and 21 control subjects viewed blocks of a repeated neutral face or neutral object, and blocks of different neutral faces and neutral objects. Habituation in the hippocampus, primary visual cortex and fusiform face area (FFA) was compared between groups. Memory for faces, words, and word pairs was assessed after the scan.
  
  
  RESULTS
  Patients showed reduced habituation to faces in the hippocampus and primary visual cortex, but not the FFA. Healthy control subjects exhibited a pattern of hippocampal discrimination that distinguished between repeated and different images for both faces and objects, and schizophrenia patients did not. Hippocampal discrimination was positively correlated with memory for word pairs.
  
  
  CONCLUSIONS
  Patients with schizophrenia showed reduced habituation of the hippocampus and visual cortex, and a lack of neural discrimination between old and new images in the hippocampus. Hippocampal discrimination correlated with memory performance, suggesting reduced habituation may contribute to the memory deficits commonly observed in schizophrenia.
authors.affiliation: Department of Psychiatry, Vanderbilt University, 1601 23rd Ave S., Nashville, TN 37212, USA. Electronic address: lewilliams1@gmail.com.
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Williams
authors.forename: Jennifer Urbano
authors.initials: JU
authors.lastname: Blackford
authors.forename: Andrew
authors.initials: A
authors.lastname: Luksik
authors.forename: Isabel
authors.initials: I
authors.lastname: Gauthier
authors.forename: Stephan
authors.initials: S
authors.lastname: Heckers
mesh_terms: D000328:Adult; D001921:Brain / Q000098:blood supply / Q000473:pathology*; D001931:Brain Mapping; D005149:Facial Expression; D005260:Female; D006185:Habituation, Psychophysiologic; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010364:Pattern Recognition, Visual; D010775:Photic Stimulation; D011569:Psychiatric Status Rating Scales; D012559:Schizophrenia / Q000150:complications* / Q000473:pathology*; D012565:Schizophrenic Psychology
keywords: Faces; Habituation; Hippocampus; Repetition suppression; Schizophrenia; fMRI adaptation