title: Differing Patterns of Altered Slow-5 Oscillations in Healthy Aging and Ischemic Stroke.
abstract: The 'default-mode' network (DMN) has been investigated in the presence of various disorders, such as Alzheimer's disease and Autism spectrum disorders. More recently, this investigation has expanded to include patients with ischemic injury. Here, we characterized the effects of ischemic injury in terms of its spectral distribution of resting-state low-frequency oscillations and further investigated whether those specific disruptions were unique to the DMN, or rather more general, affecting the global cortical system. With 43 young healthy adults, 42 older healthy adults, 14 stroke patients in their early stage (<7 days after stroke onset), and 16 stroke patients in their later stage (between 1 to 6 months after stroke onset), this study showed that patterns of cortical system disruption may differ between healthy aging and following the event of an ischemic stroke. The stroke group in the later stage demonstrated a global reduction in the amplitude of the slow-5 oscillations (0.01-0.027 Hz) in the DMN as well as in the primary visual and sensorimotor networks, two 'task-positive' networks. In comparison to the young healthy group, the older healthy subjects presented a decrease in the amplitude of the slow-5 oscillations specific to the components of the DMN, while exhibiting an increase in oscillation power in the task-positive networks. These two processes of a decrease DMN and an increase in 'task-positive' slow-5 oscillations may potentially be related, with a deficit in DMN inhibition, leading to an elevation of oscillations in non-DMN systems. These findings also suggest that disruptions of the slow-5 oscillations in healthy aging may be more specific to the DMN while the disruptions of those oscillations following a stroke through remote (diaschisis) effects may be more widespread, highlighting a non-specificity of disruption on the DMN in stroke population. The mechanisms underlying those differing modes of network disruption need to be further explored to better inform our understanding of brain function in healthy individuals and following injury.
authors.affiliation: Neuroscience Training Program, University of Wisconsin-MadisonMadison, WI, USA; Department of Radiology, University of Wisconsin-MadisonMadison, WI, USA.
authors.forename: Christian
authors.initials: C
authors.lastname: La
authors.affiliation: Department of Radiology, University of Wisconsin-Madison Madison, WI, USA.
authors.forename: Pouria
authors.initials: P
authors.lastname: Mossahebi
authors.affiliation: Department of Radiology, University of Wisconsin-Madison Madison, WI, USA.
authors.forename: Veena A
authors.initials: VA
authors.lastname: Nair
authors.affiliation: Neuroscience Training Program, University of Wisconsin-MadisonMadison, WI, USA; Department of Radiology, University of Wisconsin-MadisonMadison, WI, USA.
authors.forename: Brittany M
authors.initials: BM
authors.lastname: Young
authors.affiliation: Department of Radiology, University of Wisconsin-Madison Madison, WI, USA.
authors.forename: Julie
authors.initials: J
authors.lastname: Stamm
authors.affiliation: Department of Medical Physics, University of Wisconsin-MadisonMadison, WI, USA; Department of Psychiatry, University of Wisconsin-MadisonMadison, WI, USA.
authors.forename: Rasmus
authors.initials: R
authors.lastname: Birn
authors.affiliation: Neuroscience Training Program, University of Wisconsin-MadisonMadison, WI, USA; Department of Radiology, University of Wisconsin-MadisonMadison, WI, USA; Department of Medical Physics, University of Wisconsin-MadisonMadison, WI, USA; Department of Bio-Medical Engineering, University of Wisconsin-MadisonMadison, WI, USA.
authors.forename: Mary E
authors.initials: ME
authors.lastname: Meyerand
authors.affiliation: Neuroscience Training Program, University of Wisconsin-MadisonMadison, WI, USA; Department of Radiology, University of Wisconsin-MadisonMadison, WI, USA; Department of Medical Physics, University of Wisconsin-MadisonMadison, WI, USA; Department of Psychiatry, University of Wisconsin-MadisonMadison, WI, USA.
authors.forename: Vivek
authors.initials: V
authors.lastname: Prabhakaran
keywords: aging; fALFF; low-frequency oscillations; rs-fMRI; slow-5 oscillations; stroke