Emergence of a hierarchical brain during infancy reflected by stepwise functional connectivity

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Cognitive Neuroscience

Background:

• The brain's hierarchical functional organization is known, but its developmental emergence is unclear.
• Understanding this development is crucial for comprehending brain maturation.
• Predictive coding theories offer a framework for neural processing hierarchies.

Purpose of the Study:

• To characterize the emergence and development of the brain's hierarchical functional organization.
• To investigate how this architecture develops from infancy to adulthood.
• To explore the relationship between developing inter-sensory connectivity and cognitive development.

Main Methods:

• Utilized a modified stepwise functional connectivity analysis.
• Employed resting-state functional magnetic resonance imaging (fMRI).
• Analyzed a longitudinal sample of infants (n=28) and adults, with infant scans at birth, 1, and 2 years.

Main Results:

• Identified adult hierarchical brain organization patterns converging in limbic, paralimbic, basal ganglia, and frontoparietal regions.
• Infants gradually developed this architecture in a region- and step-dependent manner, with adult-like top hierarchical regions emerging by 1 year.
• Observed inter-sensory connectivity patterns linked to developing multisensory processing and correlated with early cognitive scores.

Conclusions:

• The brain's hierarchical organization emerges gradually during development, aligning with predictive coding models.
• Key hierarchical brain regions are established early in infancy.
• Developing inter-sensory connectivity in infancy is associated with cognitive development.