Developmental trajectories of cerebral blood flow and oxidative metabolism at baseline and during working memory tasks

Abstract

The neurobiological interpretation of developmental BOLD fMRI findings remains difficult due to the confounding issues of potentially varied baseline of brain function and varied strength of neurovascular coupling across age groups. The central theme of the present research is to study the development of brain function and neuronal activity through in vivo assessments of cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of oxygen (CMRO 2 ) both at baseline and during the performance of a working memory task in a cohort of typically developing children aged 7 to 18 years. Using a suite of 4 emerging MRI technologies including MR blood oximetry, phase-contrast MRI, pseudo-continuous arterial spin labeling (pCASL) perfusion MRI and concurrent CBF/BOLD fMRI, we found: 1) At baseline, both global CBF and CMRO 2 showed an age related decline while global OEF was stable across the age group; 2) During the working memory task, neither BOLD nor CBF responses showed significant variations with age in the activated fronto-parietal brain regions. Nevertheless, detailed voxel-wise analyses revealed sub-regions within the activated fronto-parietal regions that show significant decline of fractional CMRO 2 responses with age. These findings suggest that the brain may become more "energy efficient" with age during development.

Functional development of the brain's face‐processing system

“…They cited such factors as vascular and neuronal developmental trajectories, neurotransmitter responsiveness, and astrocyte developmental differences as potentially affecting baseline and stimulus modulated responsivity. Two recent studies appear to confirm the importance of this issue in demonstrating a negative relationship between cortical neural activities measured by estimates of oxygen metabolism and age, yet an insensitivity of the BOLD signal to this feature. That is, brain metabolism changes across age, indicating a negative correlation between neural activation and age, but the BOLD signal is relatively blind to these important changes .…”

Genetic dissection of the neuro-glio-vascular machinery in the adult brain

“…4h ). Given that astrocytes in the molecular layer of the dentate gyrus may couple neuronal activity to vascular recruitment during memory-related tasks [ 26 ], we wondered whether there would be deficits in cognitive performance. We tested iDTR mice that had been intravenously injected with CAV2- Cre and treated with DT on the open field test and a contextual memory discrimination task as illustrated in Fig.…”

In-vivo Imaging of Magnetic Fields Induced by Transcranial Direct Current Stimulation (tDCS) in Human Brain using MRI

“…Since every MRI acquisition generates phase and magnitude images, it is conceivable that target engagement (through mapping tDCS induced magnetic fields) and ensuing neurophysiological effects (through BOLD/ASL fMRI) could be simultaneously measured during a single tDCS session. One such promising technique is ASL with dual-echo EPI 32 readout to simultaneously map current induced fields, perfusion and blood oxygenation.…”