title: Contributions of the hippocampus and the striatum to simple association and frequency-based learning.
abstract: Using fMRI and a learning paradigm, this study examined the independent contributions of the hippocampus and striatum to simple association and frequency-based learning. We scanned 10 right-handed young adult subjects using a spiral in/out sequence on a GE 3.0 T scanner during performance of the learning paradigm. The paradigm consisted of 2 cues that predicted each of 3 targets with varying probabilities. Simultaneously, we varied the frequency with which each target was presented throughout the task, independent of cue associations. Subjects had shorter response latencies to frequently occurring and highly associated target stimuli and longer response latencies to infrequent target stimuli, indicating learning. Imaging results showed increased caudate activity to infrequent relative to frequent targets and increased hippocampal activity to infrequent relative to frequent cue-target associations. This work provides evidence of different neural mechanisms underlying learning based on simple frequencies versus associations within a single paradigm.
authors.affiliation: Sackler Institute for Developmental Psychobiology, Weill Medical College of Cornell University, 1300 York Avenue, Box 140, New York, NY 10021, USA. da547@nyu.edu
authors.forename: Dima
authors.initials: D
authors.lastname: Amso
authors.forename: Matthew C
authors.initials: MC
authors.lastname: Davidson
authors.forename: Scott P
authors.initials: SP
authors.lastname: Johnson
authors.forename: Gary
authors.initials: G
authors.lastname: Glover
authors.forename: B J
authors.initials: BJ
authors.lastname: Casey
mesh_terms: D000328:Adult; D001245:Association Learning / Q000502:physiology; D003463:Cues; D005260:Female; D006624:Hippocampus / Q000502:physiology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007858:Learning / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D017072:Neostriatum / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology