Utilizing fMRIĮnsured that a whole-brain assessment of performance-related connectivity would beĪccessible, allowing for the dissociation between interregional effects and We were interested in whether these measures were associated withĮncoding and subsequent recall in a paired association memory task ( Haskins et al. Here, we applied both DCM for fMRI and DCM for electroencephalography (EEG) toĬharacterize age-effects on whole-brain networks and excitatory/inhibitory Intrinsic prefrontal physiology play a role in age-related memory decline. We hypothesized that aging effects on both long-range and local Neighborhood) in neurological disorders ( BolyĢ013). (i.e., circuitry that does not directly synapse on regions outside of the local PFC 2011), and have been used toĭistinguish long-range cortical–cortical from local intrinsic cellular mediators In the assessment of dopaminergic effects on synaptic processing in the PFC ( Moran et al. These model-based analyses have been employed Processes in behaving humans has recently been made possible using dynamic causal The assessment of multiple interacting synaptic Which correlated with cognitive impairment ( Peters et al. MorphologicalĪssessments of prefrontal layer I have also revealed aģ0–60% reduction in the density of synapses in older compared with younger monkeys, Maturation is associated with a decline in intrinsic inhibitory connectivity ( Zhou et al. While in non-human primates, recentĪnalysis of in vivo electrophysiological recordings in the PFC has shown that In affecting cognitive decline ( Backman et al.Ģ006), though methodological limitations have impeded a fullerĭecomposition of task-related neurotransmission. Neurochemical change have largely implicated reduced dopaminergic neurotransmission In terms of prefrontal neurotransmitters, age-related assessments of human prefrontal Indicates pro-performance compensatory signaling or is indicative of cognitiveĭecline ( Rajah and D'Esposito 2005 Grady 2008). 2003 Davis et al.Ģ012), though it is uncertain whether heightened prefrontal activity Lateralized patterns of activation in prefrontal cortex (PFC Cabeza et al. Studies of aging cognition repeatedly demonstrate a shift to increased and less Network comprising medial temporal and posterior parietal brain regions ( Dolan and Fletcher 1997). 2004 Persson et al.Ģ006), which is recruited during successful memory encoding into a Have been found in the prefrontal cortex ( Salat et al.
With evidence for independent contributions from each of these dimensions ( He et al. Memory impairments that develop as a result of aging in the absence of pathology haveīeen attributed to changes in 3 neurobiological factors including gray matter volumeĢ011), and interregional functional connectivity ( Grady et al. That is associated with decreased memory and may be due to unstable localĪging, dynamic causal modeling, EEG, fMRI, memory Introduction Increased top-down influence of PFC upon medial temporal lobe in healthy aging Inhibition and a decrement in memory performance. TMS to the aged cohort resulted in decreased intrinsic Intervention, while the aged cohort exhibited lower E/ I ratios driven by a greater intrinsic These data revealed that the young cohort had a stable E/ I ratio that was unaffected by the TMS Transcranial magnetic stimulation (TMS) to the PFC to assess the effect onĮxcitatory/inhibitory ( E/ I) synaptic ratiosĪnd behavior. Within the PFC, DCM for EEG was employed after continuous theta burst To better understand the intrinsic activity These data revealedĮnhanced connectivity from PFC to medial temporal cortex that negativelyĬorrelated with recall ability. Involved in a memory encoding task and dynamic causal models (DCMs) for fMRI toĭetermine the causal relationships between these areas. We used fMRI to establish whole-brain networks To impact memory processing, the balance of neurotransmitters within the PFC Integrity of PFC gray matter and interregional white matter tracts are thought Hallmarks of cognitive and neurobiological human aging. Memory impairments and heightened prefrontal cortical (PFC) activity are
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