Most studies examining neurocognitive aging are based on the blood‐oxygen level‐dependent signal ... more Most studies examining neurocognitive aging are based on the blood‐oxygen level‐dependent signal obtained during functional magnetic resonance imaging (fMRI). The physiological basis of this signal is neural–vascular coupling, the process by which neurons signal cerebrovasculature to dilate in response to an increase in active neural metabolism due to stimulation. These fMRI studies of aging rely on the hemodynamic equivalence assumption that this process is not disrupted by physiologic deterioration associated with aging. Studies of neural–vascular coupling challenge this assumption and show that neural–vascular coupling is closely related to cognition. In this review, we put forward a theory of processing speed decline in aging and how it is related to age‐related neural–vascular coupling changes based on the results of studies elucidating the relationships between cognition, cerebrovascular dynamics, and aging.
Standard magnetic resonance imaging approaches offer high‐resolution but indirect measures of neu... more Standard magnetic resonance imaging approaches offer high‐resolution but indirect measures of neural activity, limiting understanding of the physiological processes associated with imaging findings. Here, we used calibrated functional magnetic resonance imaging during the resting state to recover low‐frequency fluctuations of the cerebral metabolic rate of oxygen (CMRO2). We tested whether functional connections derived from these fluctuations exhibited organization properties similar to those established by previous standard functional and anatomical connectivity studies. Seventeen participants underwent 20 min of resting imaging during dual‐echo, pseudocontinuous arterial spin labeling, and blood‐oxygen‐level dependent (BOLD) signal acquisition. Participants also underwent a 10 min normocapnic and hypercapnic procedure. Brain‐wide, CMRO2 low‐frequency fluctuations were subjected to graph‐based and voxel‐wise functional connectivity analyses. Results demonstrated that connections d...
Wearing a face mask has become essential to contain the spread of COVID-19 and has become mandato... more Wearing a face mask has become essential to contain the spread of COVID-19 and has become mandatory when collecting fMRI data at most research institutions. Here, we investigate the effects of wearing a surgical mask on fMRI data in n = 37 healthy participants. Activations during finger tapping, emotional face matching, working memory tasks, and rest were examined. Preliminary fMRI analyses show that despite the different mask states, resting-state signals and task activations were relatively similar. Resting-state functional connectivity showed negligible attenuation patterns in mask-on compared with mask-off. Task-based ROI analysis also demonstrated no significant difference between the two mask states under each contrast investigated. Notwithstanding the overall insignificant effects, these results indicate that wearing a face mask during fMRI has little to no significant effect on resting-state and task activations.
Young and old subjects performed a mental rotation task with a within-subject instructional manip... more Young and old subjects performed a mental rotation task with a within-subject instructional manipulation of speed/accuracy criteria. The three sets of instructions emphasized speed, accuracy, or both speed and accuracy equally. Both age groups changed reaction time (RT) in response to instructions, but there was no Age x Instruction interaction. Whereas young subjects showed decreases in accuracy with decreasing RT, older adults showed relatively stable levels of accuracy with decreasing RT, suggesting that young subjects were more willing to sacrifice accuracy for improvement in speed. Speed/accuracy operating characteristics for the two groups did not overlap, suggesting that age differences in response criteria cannot completely account for age differences in mental rotation performance.
Most studies examining neurocognitive aging are based on the blood‐oxygen level‐dependent signal ... more Most studies examining neurocognitive aging are based on the blood‐oxygen level‐dependent signal obtained during functional magnetic resonance imaging (fMRI). The physiological basis of this signal is neural–vascular coupling, the process by which neurons signal cerebrovasculature to dilate in response to an increase in active neural metabolism due to stimulation. These fMRI studies of aging rely on the hemodynamic equivalence assumption that this process is not disrupted by physiologic deterioration associated with aging. Studies of neural–vascular coupling challenge this assumption and show that neural–vascular coupling is closely related to cognition. In this review, we put forward a theory of processing speed decline in aging and how it is related to age‐related neural–vascular coupling changes based on the results of studies elucidating the relationships between cognition, cerebrovascular dynamics, and aging.
Standard magnetic resonance imaging approaches offer high‐resolution but indirect measures of neu... more Standard magnetic resonance imaging approaches offer high‐resolution but indirect measures of neural activity, limiting understanding of the physiological processes associated with imaging findings. Here, we used calibrated functional magnetic resonance imaging during the resting state to recover low‐frequency fluctuations of the cerebral metabolic rate of oxygen (CMRO2). We tested whether functional connections derived from these fluctuations exhibited organization properties similar to those established by previous standard functional and anatomical connectivity studies. Seventeen participants underwent 20 min of resting imaging during dual‐echo, pseudocontinuous arterial spin labeling, and blood‐oxygen‐level dependent (BOLD) signal acquisition. Participants also underwent a 10 min normocapnic and hypercapnic procedure. Brain‐wide, CMRO2 low‐frequency fluctuations were subjected to graph‐based and voxel‐wise functional connectivity analyses. Results demonstrated that connections d...
Wearing a face mask has become essential to contain the spread of COVID-19 and has become mandato... more Wearing a face mask has become essential to contain the spread of COVID-19 and has become mandatory when collecting fMRI data at most research institutions. Here, we investigate the effects of wearing a surgical mask on fMRI data in n = 37 healthy participants. Activations during finger tapping, emotional face matching, working memory tasks, and rest were examined. Preliminary fMRI analyses show that despite the different mask states, resting-state signals and task activations were relatively similar. Resting-state functional connectivity showed negligible attenuation patterns in mask-on compared with mask-off. Task-based ROI analysis also demonstrated no significant difference between the two mask states under each contrast investigated. Notwithstanding the overall insignificant effects, these results indicate that wearing a face mask during fMRI has little to no significant effect on resting-state and task activations.
Young and old subjects performed a mental rotation task with a within-subject instructional manip... more Young and old subjects performed a mental rotation task with a within-subject instructional manipulation of speed/accuracy criteria. The three sets of instructions emphasized speed, accuracy, or both speed and accuracy equally. Both age groups changed reaction time (RT) in response to instructions, but there was no Age x Instruction interaction. Whereas young subjects showed decreases in accuracy with decreasing RT, older adults showed relatively stable levels of accuracy with decreasing RT, suggesting that young subjects were more willing to sacrifice accuracy for improvement in speed. Speed/accuracy operating characteristics for the two groups did not overlap, suggesting that age differences in response criteria cannot completely account for age differences in mental rotation performance.
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