Left frontal hub connectivity enhances task-related brain network segregation and cognition in ageing - implications for cognitive reserve

Frontzkowski, Lukas Karl (2022): Left frontal hub connectivity enhances task-related brain network segregation and cognition in ageing - implications for cognitive reserve. Dissertation, LMU München: Medizinische Fakultät

Abstract

Global functional connectivity of the left frontal cortex (LFC), a hub of the cognitive control network, is associated with higher fluid intelligence and relatively preserved cognition despite age- and Alzheimer’s disease (AD)-related brain changes, rendering LFC connectivity a candidate substrate of cognitive reserve. Yet, the mechanisms by which LFC connectivity supports cognition are unclear. Given that the control network, and in particular the LFC, is thought to orchestrate activity of other functional networks, the main hypothesis underlying this doctoral thesis was that the association between LFC connectivity and higher cognitive abilities such as executive function is mediated via an enhanced network segregation. Functional network segregation is defined as the degree of how much the brain is organized in distinct networks that are characterized by a higher intra-network connectivity and a lower inter-network connectivity. The main hypothesis was tested by examining a data set containing information about 255 participants aged between 20 and 80 years who participated in twelve fMRI tasks covering a range of four cognitive domains. For each participant, global LFC connectivity was assessed and associations with performance scores and network segregation were tested. Higher global LFC connectivity was associated with higher performance scores in fluid reasoning tasks which was partially mediated by an enhanced network segregation. These findings show that LFC connectivity increases fluid reasoning task performance in normal aging via an enhanced brain network segregation, suggesting a potential mechanism by which LFC connectivity supports cognitive function, and potentially cognitive reserve.

• Dokumententyp: Dissertationen (Dissertation, LMU München)
• Keywords: fMRI, Cognitive reserve, MRI, Neuroscience, Alzheimer, Neurology, Network, Graph Theory
• Themengebiete: 600 Technik, Medizin, angewandte Wissenschaften ; 600 Technik, Medizin, angewandte Wissenschaften > 610 Medizin und Gesundheit
• Fakultäten: Medizinische Fakultät
• Sprache der Hochschulschrift: Englisch
• Datum der mündlichen Prüfung: 12. Dezember 2022
• 1. Bericht­erstatter:in: Ewers, Michael