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An fMRI study of stimulus equivalence

Dickins, David W.CA; Singh, Krish D.1; Roberts, Neil1; Burns, Patrick; Downes, John J.; Jimmieson, Phil3; Bentall, Richard P.4

Brain Imaging
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In order to study brain activation during the formation of equivalence relations, 12 subjects underwent fMRI during matching-to-sample (MTS) tests of (1) previously trained arbitrary relationships between iconic stimuli and the untrained, emergent relations of (2) symmetry, (3) transitivity, and (4) symmetry with transitivity, plus a test of verbal fluency (VF). Brain activation was similar in all MTS tasks and in the VF task. In particular, both types of task activated dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex bilaterally. However VF, but not the MTS tasks, activated Broca's area. In three of the four MTS tasks, behavioural accuracy was significantly correlated with left lateralisation of DLPFC activity. Brain activation patterns during equivalence thus resembled those involved in semantic processing underlying language, without involving regions concerned with the simple sub-vocal articulation of stimulus names.

Department of Psychology, University of Liverpool, ERB, Bedford Street South, Liverpool L69 7ZA; 1Magnetic Resonance and Image Analysis Research Centre, University of Liverpool and Walton Centre for Neurology and Neurosurgery; 2Department of Psychology, University of Liverpool; 3Department of Computer Science, University of Liverpool; 4Department of Psychology, University of Manchester, UK

CACorresponding Author: dickins@liverpool.ac.uk

Received 8 November 2000; accepted 24 November 2000

© 2001 Lippincott Williams & Wilkins, Inc.