Functional constraints in the evolution of brain circuits.

Area of Science:

• Neuroscience
• Evolutionary Biology
• Computational Neuroscience

Background:

• The vertebrate isocortex exhibits conserved anatomical and neurodevelopmental organization across species.
• Information processing in the isocortex involves complex networks of excitatory and inhibitory neurons with reciprocal connections across layers.
• Dynamical brain networks, organized in neuronal assemblies with rhythmic phase relationships, are crucial for sensory, motor, and cognitive functions.

Purpose of the Study:

• To explore how functional requirements of the isocortex explain its evolutionary stability in microcircuit organization across vertebrates.
• To propose that isocortex architectures are canonical microcircuits shaped by evolutionary pressures.
• To investigate the role of oscillatory activity and predictive coding in this conserved structure.

Main Methods:

• This is a perspective piece, proposing theoretical frameworks rather than presenting empirical data.
• It synthesizes existing knowledge on isocortex organization, neuronal oscillations, and predictive coding.
• The study analyzes functional constraints and evolutionary advantages of specific neural processing strategies.

Main Results:

• Isocortex architecture is proposed to be a result of early selection for neuronal architectures based on excitatory-inhibitory balance, leading to compartmentalized oscillations.
• The subsequent emergence of inferential coding strategies (predictive coding) expanded computational capacities.
• Similarities in brain circuitry across vertebrates may reflect evolutionary constraints imposed by functional requirements.

Conclusions:

• Functional requirements, particularly the excitatory-inhibitory balance and predictive coding, are key drivers of the conserved microcircuitry in the vertebrate isocortex.
• Oscillatory activity offers advantages for information transmission and code reliability in brain networks.
• The evolutionary stability of isocortex organization may be a result of convergent functional demands rather than solely shared ancestry.