INTRODUCTION: PET, SPECT and functional magnetic resonance imaging studies have allowed the delineation of brain circuits activated during several types of cognitive tasks. The field of declarative memory has been one of the most extensively investigated. In the present study, the regional cerebral blood flow (rCBF) SPECT technique was used to investigate changes in brain activity during a verbal memory task in a group of elderly healthy volunteers (n=15). METHODS:Two SPECT acquisitions were performed in the same session, using the split-dose 99mTc-HMPAO technique. Measures of rCBF were taken during a recognition memory task and a simpler control task. Between-task comparisons were performed automatically using the Statistical Parametric Mapping (SPM) program. RESULTS: Increased rCBF during the memory task was seen in several brain regions, including: the lateral prefrontal cortex on both hemispheres (more intensely on the left side); posterior and medial portions of the left occipital and parietal cortices; the right and left cerebellar hemispheres; and the right and left lateral temporal cortex (p<0.001, uncorrected for multiple comparisons). Unexpected foci of decreased rCBF were seen in the right posterior cingulate cortex, left orbitofrontal cortex, right inferior temporal cortex and left cerebellar vermis (p<0.05, corrected for multiple comparisons). CONCLUSION:These results suggest that multifocal neural circuits are engaged during recognition memory, and replicate locations seen in previous studies in the literature. The use of the protocols described here in patients with neuropsychiatric disorders may allow investigation of brain abnormalities underlying the memory deficits seen in these disorders.
Tomography; Tomography; Memory; Regional blood flow; Brain; Aging; Cognition
