Nomi, Jason S.; Bzdok, Danilo; Li, Jingwei; Bolt, Taylor; Chang, Catie; Kornfeld, Salome; Goodman, Zachary T.; Yeo, B.T. Thomas; Spreng, R. Nathan; Uddin, Lucina Q. Imaging Neuroscience 2 (2024): 1-13. .听
In brain imaging studies using听resting-state fMRI, scientists often detect a signal called the听global signal (GS). While this signal is known to include noise and artifacts (like breathing or head motion), it also carries important information about brain activity that reflects a person鈥檚 mental state and traits.听
This study looked at how the GS changes with听age, using data from people aged听6 to 85. Researchers found that different brain regions contribute to the GS in different ways across the lifespan.听
- Subcortical areas听(deep parts of the brain), such as the听thalamus听and听putamen, showed听linear changes. The thalamus contributed more to the GS as people got older, while the putamen contributed more in younger people.听
- Another deep brain structure, the听nucleus basalis of Meynert, showed a听U-shaped pattern: stronger contributions in children and older adults, and weaker in middle-aged adults. A similar pattern was seen in听cortical regions听(outer brain areas), especially in networks related to attention and thinking (like the听frontoparietal network).听
These patterns suggest that the GS is made up of two layers: one from subcortical areas and another from cortical areas, and that their roles in the GS change with age.听
Overall, this research shows that the GS isn鈥檛 just noise鈥攊t contains meaningful brain activity that听changes throughout life. Because of this, scientists should be cautious when choosing to remove it in studies that explore how the brain develops or ages.听
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Fig. 1.听
Average global signal topography across 10-year age groups. Increased associations between the GS with visual, sensorimotor, and prefrontal cortical regions are found across each age group.听
