title: The burden of microstructural damage modulates cortical activation in elderly subjects with MCI and leuko-araiosis. A DTI and fMRI study.
abstract: The term leuko-araiosis (LA) describes a common chronic affection of the cerebral white matter (WM) in the elderly due to small vessel disease with variable clinical correlates. To explore whether severity of LA entails some adaptive reorganization in the cerebral cortex we evaluated with functional MRI (fMRI) the cortical activation pattern during a simple motor task in 60 subjects with mild cognitive impairment and moderate or severe (moderate-to-severe LA group, n = 46) and mild (mild LA group, n = 14) LA extension on visual rating. The microstructural damage associated with LA was measured on diffusion tensor data by computation of the mean diffusivity (MD) of the cerebral WM and by applying tract based spatial statistics (TBSS). Subjects were examined with fMRI during continuous tapping of the right dominant hand with task performance measurement. Moderate-to-severe LA group showed hyperactivation of left primary sensorimotor cortex (SM1) and right cerebellum. Regression analyses using the individual median of WM MD as explanatory variable revealed a posterior shift of activation within the left SM1 and hyperactivation of the left SMA and paracentral lobule and of the bilateral cerebellar crus. These data indicate that brain activation is modulated by increasing severity of LA with a local remapping within the SM1 and increased activity in ipsilateral nonprimary sensorimotor cortex and bilateral cerebellum. These potentially adaptive changes as well lack of contralateral cerebral hemisphere hyperactivation are in line with sparing of the U fibers and brainstem and cerebellar WM tracts and the emerging microstructual damage of the corpus callosum revealed by TBSS with increasing severity of LA.
authors.affiliation: Radiodiagnostic Section, Department of Clinical Physiopathology, University of Florence, Florence, Italy.
authors.forename: Mario
authors.initials: M
authors.lastname: Mascalchi
authors.forename: Andrea
authors.initials: A
authors.lastname: Ginestroni
authors.forename: Nicola
authors.initials: N
authors.lastname: Toschi
authors.forename: Anna
authors.initials: A
authors.lastname: Poggesi
authors.forename: Paolo
authors.initials: P
authors.lastname: Cecchi
authors.forename: Emilia
authors.initials: E
authors.lastname: Salvadori
authors.forename: Carlo
authors.initials: C
authors.lastname: Tessa
authors.forename: Mirco
authors.initials: M
authors.lastname: Cosottini
authors.forename: Nicola
authors.initials: N
authors.lastname: De Stefano
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pracucci
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pantoni
authors.forename: Domenico
authors.initials: D
authors.lastname: Inzitari
authors.forename: Stefano
authors.initials: S
authors.lastname: Diciotti
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001921:Brain / Q000166:cytology / Q000473:pathology* / Q000503:physiopathology; D001931:Brain Mapping / Q000295:instrumentation / Q000379:methods*; D002531:Cerebellum / Q000166:cytology / Q000473:pathology / Q000503:physiopathology; D060825:Cognitive Dysfunction / Q000473:pathology* / Q000503:physiopathology; D056324:Diffusion Tensor Imaging / Q000295:instrumentation / Q000379:methods*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D049292:Leukoaraiosis / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D009044:Motor Cortex / Q000166:cytology / Q000473:pathology / Q000503:physiopathology; D012720:Severity of Illness Index