QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

The Journal of Neuroscience, September 2, 2009, 29(35):10900-10908; doi:10.1523/JNEUROSCI.1202-09.2009

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Greenberg, D. L. Articles by Verfaellie, M. PubMed PubMed Citation Articles by Greenberg, D. L. Articles by Verfaellie, M.

 Previous Article  |  Next Article 

Behavioral/Systems/Cognitive
Impaired Category Fluency in Medial Temporal Lobe Amnesia: The Role of Episodic Memory

Daniel L. Greenberg,¹ Margaret M. Keane,^1,2 Lee Ryan,³ and Mieke Verfaellie¹

¹Memory Disorders Research Center, Veterans Affairs Boston Healthcare System, Boston University, Boston, Massachusetts 02130, ²Psychology Department, Wellesley College, Wellesley, Massachusetts 02482, and ³Cognition and Neuroimaging Laboratories, Psychology Department, University of Arizona, Tucson, Arizona 85721

Correspondence should be addressed to Daniel L. Greenberg, Memory Disorders Research Center, 150 South Huntington Avenue (151-A), Veterans Affairs Boston Healthcare System, Boston University, Boston, MA 02130. Email: dlg{at}bu.edu

Memory tasks are often classified as semantic or episodic, but recent research shows that these types of memory are highly interactive. Category fluency, for example, is generally considered to reflect retrieval from semantic memory, but behavioral evidence suggests that episodic memory is also involved: participants frequently draw on autobiographical experiences while generating exemplars of certain categories. Neuroimaging studies accordingly have reported increased medial temporal lobe (MTL) activation during exemplar generation. Studies of fluency in MTL amnesics have yielded mixed results but were not designed to determine the precise contributions of episodic memory. We addressed this issue by asking MTL amnesics and controls to generate exemplars of three types of categories. One type tended to elicit autobiographical and spatial retrieval strategies (AS). Another type elicited strategies that were autobiographical but nonspatial (AN). The third type elicited neither autobiographical nor spatial strategies (N). Amnesic patients and control participants generated exemplars for eight categories of each type. Patients were impaired on all category types but were more impaired on AS and AN categories. After covarying for phonemic fluency (total FAS score), the N category impairment was not significant, but the impairment on AS and AN categories remained. The same results were obtained for patients with lesions restricted to the MTL and those with more extensive lesions. We conclude that patients' episodic memory impairment hindered their performance on this putatively semantic task. This interaction between episodic and semantic memory might partially account for fluency deficits seen in aging, mild cognitive impairment, and Alzheimer's disease.

---

Received March 10, 2009; revised June 14, 2009; accepted June 23, 2009.

Correspondence should be addressed to Daniel L. Greenberg, Memory Disorders Research Center, 150 South Huntington Avenue (151-A), Veterans Affairs Boston Healthcare System, Boston University, Boston, MA 02130. Email: dlg{at}bu.edu

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help