title: Neurovascular coupling in normal aging: a combined optical, ERP and fMRI study.
abstract: Brain aging is characterized by changes in both hemodynamic and neuronal responses, which may be influenced by the cardiorespiratory fitness of the individual. To investigate the relationship between neuronal and hemodynamic changes, we studied the brain activity elicited by visual stimulation (checkerboard reversals at different frequencies) in younger adults and in older adults varying in physical fitness. Four functional brain measures were used to compare neuronal and hemodynamic responses obtained from BA17: two reflecting neuronal activity (the event-related optical signal, EROS, and the C1 response of the ERP), and two reflecting functional hemodynamic changes (functional magnetic resonance imaging, fMRI, and near-infrared spectroscopy, NIRS). The results indicated that both younger and older adults exhibited a quadratic relationship between neuronal and hemodynamic effects, with reduced increases of the hemodynamic response at high levels of neuronal activity. Although older adults showed reduced activation, similar neurovascular coupling functions were observed in the two age groups when fMRI and deoxy-hemoglobin measures were used. However, the coupling between oxy- and deoxy-hemoglobin changes decreased with age and increased with increasing fitness. These data indicate that departures from linearity in neurovascular coupling may be present when using hemodynamic measures to study neuronal function.
authors.affiliation: University of Illinois at Urbana-Champaign, USA. Electronic address: mfabiani@illinois.edu.
authors.forename: Monica
authors.initials: M
authors.lastname: Fabiani
authors.forename: Brian A
authors.initials: BA
authors.lastname: Gordon
authors.forename: Edward L
authors.initials: EL
authors.lastname: Maclin
authors.forename: Melanie A
authors.initials: MA
authors.lastname: Pearson
authors.forename: Carrie R
authors.initials: CR
authors.lastname: Brumback-Peltz
authors.forename: Kathy A
authors.initials: KA
authors.lastname: Low
authors.forename: Edward
authors.initials: E
authors.lastname: McAuley
authors.forename: Bradley P
authors.initials: BP
authors.lastname: Sutton
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Kramer
authors.forename: Gabriele
authors.initials: G
authors.lastname: Gratton
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001808:Blood Vessels / Q000294:innervation* / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D004522:Educational Status; D004569:Electroencephalography / Q000379:methods*; D005071:Evoked Potentials / Q000502:physiology*; D005260:Female; D006454:Hemoglobins / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010775:Photic Stimulation; D011597:Psychomotor Performance / Q000502:physiology; D041622:Tomography, Optical / Q000379:methods*; D055815:Young Adult
chemical_list: D006454:Hemoglobins
keywords: Aging; Event-related brain potentials (ERPs); Event-related optical signal (EROS); Fitness; Functional magnetic resonance imaging (fMRI); Near-infrared spectroscopy (NIRS); Neurovascular coupling