Imagine exploring a vast network of interconnected highways, each with its own traffic flow and purpose. That’s exactly what researchers did when studying the sensorimotor system in young and older individuals. By analyzing resting-state functional MRI data, they uncovered fascinating differences between the two age groups. In young individuals, information flowed efficiently and rapidly, like cars zipping along unidirectional roads from primary motor and sensory areas to higher-order regions. However, in older individuals, the network became more complex, resembling a tangled web of intertwining connections. Information originated from different brain regions before passing through loosely connected motor areas and finally reaching primary motor and sensory regions. Interestingly, older individuals who exhibited pathways similar to those found in young individuals also had a positive correlation with years of education. This suggests that continued learning may help maintain efficient information transfer within the brain’s infrastructure. To delve deeper into this intriguing research on brain connectivity and organization, check out the full article!

IntroductionStudies in the sensorimotor system of older versus young individuals have shown alterations in functional connectivity and organization. Our objective was to explore the implications of these differences in terms of local organizations, and to identify processes that correlate with neuropsychological parameters.MethodsUsing a novel multivariate analysis method on resting-state functional MRI data obtained from 50 young and 31 older healthy individuals, we identified directed 4-node functional pathways within the sensorimotor system and examined their correlations with neuropsychological assessments.ResultsIn young individuals, the functional pathways were unidirectional, flowing from the primary motor and sensory cortices to higher motor and visual regions. In older individuals, the functional pathways were more complex. They originated either from the calcarine sulcus or the insula and passed through mutually coupled high-order motor areas before reaching the primary sensory and motor cortices. Additionally, the pathways in older individuals that resembled those found in young individuals exhibited a positive correlation with years of education.DiscussionThe flow pattern of young individuals suggests efficient and fast information transfer. In contrast, the mutual coupling of high-order motor regions in older individuals suggests an inefficient and slow transfer, a less segregated and a more integrated organization. The differences in the number of sensorimotor pathways and of their directionality suggests reduced efferent degenerated pathways and increased afferent compensated pathways. Furthermore, the positive effect of years of education may be associated with the Cognitive Reserve Hypothesis, implying that cognitive reserve could be maintained through specific information transfer pathways.

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