Brain connectomes come of age

Area of Science:

• Neuroscience
• Computational Neuroscience
• Connectomics

Background:

• Recent advances provide consistent, directed, and weighted inter-areal brain connectivity data for mouse, macaque, and marmoset models.
• Cortical connections, particularly laminar patterns, define structural brain hierarchies.
• Existing models are increasingly incorporating this detailed connectivity information.

Purpose of the Study:

• To demonstrate how connectomics data can inform the development of structurally based dynamic models of multi-regional brain systems.
• To explore the relationship between structural hierarchy, dynamical properties, and information processing in the brain.
• To highlight how quantitative connectomic data can guide future empirical research.

Main Methods:

• Utilizing newly available databases of directed and weighted inter-areal cortical connectivity.
• Developing large-scale dynamical models of brain systems, incorporating laminar structures.
• Analyzing signal propagation in spiking neuron models to identify phenomena like stimulus thresholds.

Main Results:

• A dynamical model of macaque cortex with laminar structure successfully replicated observed frequency-modulated interplay between bottom-up and top-down processes.
• Spiking neuron models exhibited a stimulus amplitude threshold for signal access to prefrontal cortex, akin to conscious perception's ignition phenomenon.
• Comparative analysis revealed both similarities and differences in connectivity matrices across species (mouse, macaque, marmoset).

Conclusions:

• Connectomic data provide crucial quantitative insights for structural and dynamical modeling of cortical circuits, enhancing understanding of global brain function.
• Quantification of cortical hierarchy is essential for investigating the interplay between bottom-up and top-down information processing.
• This integration of connectomics and modeling theory generates novel hypotheses for experimental validation, fostering collaboration between theorists and experimentalists.