title: The neural correlates of implicit sequence learning in schizophrenia.
abstract: Twenty-seven schizophrenia spectrum patients and 25 healthy controls performed a probabilistic version of the serial reaction time task (SRT) that included sequence trials embedded within random trials. Patients showed diminished, yet measurable, sequence learning. Postexperimental analyses revealed that a group of patients performed above chance when generating short spans of the sequence. This high-generation group showed SRT learning that was similar in magnitude to that of controls. Their learning was evident from the very 1st block; however, unlike controls, learning did not develop further with continued testing. A subset of 12 patients and 11 controls performed the SRT in conjunction with positron emission tomography. High-generation performance, which corresponded to SRT learning in patients, correlated to activity in the premotor cortex and parahippocampus. These areas have been associated with stimulus-driven visuospatial processing. Taken together, these results suggest that a subset of patients who showed moderate success on the SRT used an explicit stimulus-driven strategy to process the sequential stimuli. This adaptive strategy facilitated sequence learning but may have interfered with conventional implicit learning of the overall stimulus pattern.
authors.affiliation: Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, USA. cmarvell@jhmi.edu
authors.forename: Cherie L
authors.initials: CL
authors.lastname: Marvel
authors.forename: Beth M
authors.initials: BM
authors.lastname: Turner
authors.forename: Daniel S
authors.initials: DS
authors.lastname: O'Leary
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Johnson
authors.forename: Ronald K
authors.initials: RK
authors.lastname: Pierson
authors.forename: Laura L Boles
authors.initials: LL
authors.lastname: Ponto
authors.forename: Nancy C
authors.initials: NC
authors.lastname: Andreasen
mesh_terms: D000328:Adult; D001931:Brain Mapping; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010775:Photic Stimulation / Q000379:methods; D049268:Positron-Emission Tomography / Q000379:methods; D011930:Reaction Time / Q000502:physiology; D012559:Schizophrenia / Q000000981:diagnostic imaging / Q000473:pathology* / Q000503:physiopathology*; D012691:Serial Learning / Q000502:physiology*