title: Posterior parietal cortex activity predicts individual differences in visual short-term memory capacity.
abstract: Humans show a severe capacity limit in the number of objects they can store in visual short-term memory (VSTM). We recently demonstrated with functional magnetic resonance imaging that VSTM storage capacity estimated in averaged group data correlated strongly with posterior parietal/superior occipital cortex activity (Todd & Marois, 2004). However, individuals varied widely in their VSTM capacity. Here, we examined the neural basis of these individual differences. A voxelwise, individual-differences analysis revealed a significant correlation between posterior parietal cortex (PPC) activity and individuals' VSTM storage capacity. In addition, a region-of-interest analysis indicated that other brain regions, particularly visual occipital cortex, may contribute to individual differences in VSTM capacity. Thus, although not ruling out contributions from other brain regions, the individual-differences approach supports a key role for the PPC in VSTM by demonstrating that its activity level predicts individual differences in VSTM storage capacity.
authors.affiliation: Vanderbilt Vision Research Center, Department of Psychology, Vanderbilt University, 530 Wilson Hall, 111 21st Ave. S., Nashville, TN 37203, USA.
authors.forename: J Jay
authors.initials: JJ
authors.lastname: Todd
authors.forename: René
authors.initials: R
authors.lastname: Marois
mesh_terms: D000293:Adolescent; D000328:Adult; D001931:Brain Mapping; D005260:Female; D007839:Functional Laterality; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007206:Individuality; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010296:Parietal Lobe / Q000098:blood supply / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation / Q000379:methods; D011237:Predictive Value of Tests; D013223:Statistics as Topic
chemical_list: D010100:Oxygen