title: Frontal and parietal contributions to probabilistic association learning.
abstract: Neuroimaging studies have shown both dorsolateral prefrontal (DLPFC) and inferior parietal cortex (iPARC) activation during probabilistic association learning. Whether these cortical brain regions are necessary for probabilistic association learning is presently unknown. Participants' ability to acquire probabilistic associations was assessed during disruptive 1 Hz repetitive transcranial magnetic stimulation (rTMS) of the left DLPFC, left iPARC, and sham using a crossover single-blind design. On subsequent sessions, performance improved relative to baseline except during DLPFC rTMS that disrupted the early acquisition beneficial effect of prior exposure. A second experiment examining rTMS effects on task-naive participants showed that neither DLPFC rTMS nor sham influenced naive acquisition of probabilistic associations. A third experiment examining consecutive administration of the probabilistic association learning test revealed early trial interference from previous exposure to different probability schedules. These experiments, showing disrupted acquisition of probabilistic associations by rTMS only during subsequent sessions with an intervening night's sleep, suggest that the DLPFC may facilitate early access to learned strategies or prior task-related memories via consolidation. Although neuroimaging studies implicate DLPFC and iPARC in probabilistic association learning, the present findings suggest that early acquisition of the probabilistic cue-outcome associations in task-naive participants is not dependent on either region.
authors.affiliation: School of Psychiatry, University of New South Wales, Randwick, New South Wales 2031, Australia.
authors.forename: Jacqueline A
authors.initials: JA
authors.lastname: Rushby
authors.forename: Ans
authors.initials: A
authors.lastname: Vercammen
authors.forename: Colleen
authors.initials: C
authors.lastname: Loo
authors.forename: Brooke
authors.initials: B
authors.lastname: Short
authors.forename: Cynthia Shannon
authors.initials: CS
authors.lastname: Weickert
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Weickert
mesh_terms: D000293:Adolescent; D000328:Adult; D001245:Association Learning / Q000502:physiology* / Q000528:radiation effects; D018592:Cross-Over Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010296:Parietal Lobe / Q000033:anatomy & histology / Q000502:physiology* / Q000528:radiation effects; D017397:Prefrontal Cortex / Q000033:anatomy & histology / Q000502:physiology* / Q000528:radiation effects; D011337:Probability Learning; D011446:Prospective Studies; D016037:Single-Blind Method; D050781:Transcranial Magnetic Stimulation / Q000009:adverse effects / Q000379:methods; D055815:Young Adult