Transitive inference in healthy humans and implications for schizophrenia

Transitive inference (TI) refers to inferences on relations between items based on other known relations of those items. Using a paradigm where participants first learn a series of four overlapping pairs that constitute the ordered sequence A>B>C>D>E and are then tested on the novel TI pair BD and non-TI pair AE, animal experiments demonstrated that intact function of the hippocampus is necessary for TI but not for non-TI. We performed three functional magnetic resonance imaging (fMRI) experiments to identify neural correlates of TI in healthy humans. First, we show hippocampal activation in learning overlapping pairs that constitute an ordered sequence but not non-overlapping individual pairs. Second, we demonstrate hippocampal recruitment in inferences on the ordered sequence of overlapping pairs (TI) but not on non-overlapping pairs (non-TI, e.g., if a>b and c>d then a>d). We then demonstrate the specificity of hippocampal activation to TI on pairs that are devoid of sequence end-items (e.g., B>D vs. A>C). The results support the relational flexibility account of hippocampal function.

Department dc:contributor.department

Harvard University--MIT Division of Health Sciences and Technology

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2006

Author dc:creator

• Zalesak, M. (Martin)

Advisor dc:contributor.advisor

• Stephan H. Heckers.

• Harvard University--MIT Division of Health Sciences and Technology.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/38247

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/38247