title: Fractal analysis of striatal dopamine re-uptake sites.
abstract: Spatial variation in regional blood flow, metabolism and receptor density within the brain and in other organs is measurable even with a low spatial resolution technique such as emission tomography. It has been previously shown that the observed variance increases with increasing number of subregions in the organ/tissue studied. This resolution-dependent variance can be described by fractal analysis. We studied striatal dopamine re-uptake sites in 39 healthy volunteers with high-resolution single-photon emission tomography using iodine-123 labelled 2beta-carbomethoxy-3beta-(4-iodophenyl)tropane ([123I]beta-CIT). The mean fractal dimension was 1.15+/-0.07. The results indicate that regional striatal dopamine re-uptake sites involve considerable spatial heterogeneity which is higher than the uniform density (dimension=1.00) but much lower than complete randomness (dimension=1.50). There was a gender difference, with females having a higher heterogeneity in both the left and the right striatum. In addition, we found striatal asymmetry (left-to-right heterogeneity ratio of 1.19+/-0.15; P<0.001), suggesting functional hemispheric lateralization consistent with the control of motor behaviour and integrative functions.
authors.affiliation: Department of Clinical Physiology, Kuopio University Hospital, Kuopio, Finland.
authors.forename: J T
authors.initials: JT
authors.lastname: Kuikka
authors.forename: J
authors.initials: J
authors.lastname: Tiihonen
authors.forename: J
authors.initials: J
authors.lastname: Karhu
authors.forename: K A
authors.initials: KA
authors.lastname: Bergström
authors.forename: P
authors.initials: P
authors.lastname: Räsänen
mesh_terms: D000328:Adult; D002352:Carrier Proteins / Q000378:metabolism; D003042:Cocaine / Q000031:analogs & derivatives*; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000378:metabolism; D004298:Dopamine / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins; D005260:Female; D017709:Fractals; D006801:Humans; D007457:Iodine Radioisotopes; D016018:Least-Squares Analysis; D008297:Male; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods / Q000706:statistics & numerical data
chemical_list: D002352:Carrier Proteins; D050483:Dopamine Plasma Membrane Transport Proteins; D007457:Iodine Radioisotopes; D008562:Membrane Glycoproteins; D026901:Membrane Transport Proteins; D009419:Nerve Tissue Proteins; C069723:2beta-carbomethoxy-3beta-(4-iodophenyl)tropane; D003042:Cocaine; D004298:Dopamine