MEASUREMENTS OF RETRIEVAL ACTIVATION FOR AUTOBIOGRAPHICAL VERSUS IMPERSONAL EVENTS USING FMRI
Abstract number :
1.247
Submission category :
Year :
2002
Submission ID :
857
Source :
www.aesnet.org
Presentation date :
12/7/2002 12:00:00 AM
Published date :
Dec 1, 2002, 06:00 AM
Authors :
Paraskevi V. Rekkas, Michael Westerveld, Dennis D. Spencer, R. Todd Constable. Diagnostic Radiology, Yale University, New Haven, CT; Neurosurgery, Yale University, New Haven, CT
RATIONALE: Our goal was to provide normative data on the systems involved in remote memory retrieval and determine the implications for temporal lobe resection in epilepsy.
METHODS: The retrieval of autobiographical memories versus impersonal, historic events was investigated in an fMRI design that further distinguished between spatial and temporal memory judgements. A word/non-word decision task, designed to control for language processing, served as the baseline measure. Ten subjects were scanned at 1.5 Tesla using gradient-echo echo-planer imaging in a repeated measures, block design. The images, performed on the coronal-oblique plane perpendicular to the hippocampus, were subsequently subjected to motion correction.
RESULTS: Region of interest analyses indicated that autobiographic events tended to produce the greatest measure of activation in posterior, bilateral regions of the mid-frontal gyri, while activation for impersonal events was more rostral and significant only in the right hemisphere. Most striking, judgements about the relative location of autobiographical and impersonal events showed significantly greater activation (p [lt] .025) in bilateral regions of the dorsolateral prefrontal cortex (DLPFC) than did judgements about the sequence of events in time. Most conditions resulted in activation of the left hippocampus (p [lt] .025) however location judgements about autobiographical events also produced borderline deactivation (p = .054) in the right hippocampus relative to baseline.
CONCLUSIONS: Autobiographic memories, especially those related to location, result in greater overall activation in DLPFC than do impersonal events. It is unclear if this is because these types of questions produce greater demands to working memory systems or if autobiographical memory networks are more widely distributed throughout this region of cortex. Regardless, the activation seen in the left hippocampus for most conditions, and deactivation seen in the right hippocampus in response to questions about autobiographical location, suggest that it may work in conjunction with the DLPFC to facilitate memory judgements.
[Supported by: NIH NS38467 NS40497]