Impaired familiarity with preserved recollection after anterior temporal-lobe resection that spares the hippocampus

doi:10.1073/pnas.0705273104

Impaired familiarity with preserved recollection after anterior temporal-lobe resection that spares the hippocampus

*Department of Psychology, University of Western Ontario, London, ON, Canada N6A 5C2;
^§Department of Psychology, University of California, Davis, CA 95616;
^†Clinical Neurological Sciences, University of Western Ontario, London Health Sciences Centre, London, ON, Canada N6A 5A5; and
^‡Department of Psychiatry, McGill University, Montreal, PQ, Canada H4H 1R3

Edited by Edward E. Smith, Columbia University, New York, NY, and approved August 9, 2007 (received for review June 5, 2007)

Abstract

It is well established that the medial-temporal lobe (MTL) is critical for recognition memory. The MTL is known to be composed of distinct structures that are organized in a hierarchical manner. At present, it remains controversial whether lower structures in this hierarchy, such as perirhinal cortex, support memory functions that are distinct from those of higher structures, in particular the hippocampus. Perirhinal cortex has been proposed to play a specific role in the assessment of familiarity during recognition, which can be distinguished from the selective contributions of the hippocampus to the recollection of episodic detail. Some researchers have argued, however, that the distinction between familiarity and recollection cannot capture functional specialization within the MTL and have proposed single-process accounts. Evidence supporting the dual-process view comes from demonstrations that selective hippocampal damage can produce isolated recollection impairments. It is unclear, however, whether temporal-lobe lesions that spare the hippocampus can produce selective familiarity impairments. Without this demonstration, single-process accounts cannot be ruled out. We examined recognition memory in NB, an individual who underwent surgical resection of left anterior temporal-lobe structures for treatment of intractable epilepsy. Her resection included a large portion of perirhinal cortex but spared the hippocampus. The results of four experiments based on three different experimental procedures (remember-know paradigm, receiver operating characteristics, and response-deadline procedure) indicate that NB exhibits impaired familiarity with preserved recollection. The present findings thus provide a crucial missing piece of support for functional specialization in the MTL.

Footnotes

^¶To whom correspondence should be addressed. E-mail: stefank{at}uwo.ca
Author contributions: B.B., C.C., S.E.P., and S.K. designed research; B.B., C.C., S.M.M., S.E.P., J.C.P., and S.K. performed research; A.G.P. and A.P.Y. contributed new analytic tools; B.B. and J.C.P. analyzed data; and B.B., S.M.M., A.P.Y., and S.K. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0705273104/DC1.
Abbreviations:

MTL,

medial-temporal lobe;

ROC,

receiver operating characteristics;

RK,

remember-know.
Freely available online through the PNAS open access option.