Allometric rules for mammalian cortical layer 5 neuron biophysics.

Area of Science:

• Neuroscience
• Computational Neuroscience
• Evolutionary Biology

Background:

• Neuronal biophysical properties are fundamental to brain computation.
• Neuronal size varies significantly across species and influences single neuron function.
• It remains unclear if neuronal properties adapt across species to maintain consistent information processing.

Purpose of the Study:

• To investigate the allometric relationships governing neuronal biophysics in layer 5 cortical pyramidal neurons across 10 mammalian species.
• To determine if neuronal properties are conserved across species to maintain consistent information processing.
• To identify evolutionary principles of neuronal biophysics and compare human cortical neurons.

Main Methods:

• Characterization of layer 5 cortical pyramidal neurons from 10 mammalian species.
• Analysis of allometric scaling rules for neuronal biophysical properties related to cell size.
• Quantification of voltage-gated potassium and HCN channel conductances.

Main Results:

• Conserved scaling rules for voltage-gated potassium and HCN channel conductances were found in 9 of 10 species.
• Larger neurons exhibited higher membrane ionic conductances, maintaining conserved conductance per unit brain volume.
• Human neurons showed significantly lower voltage-gated potassium and HCN conductances compared to allometric predictions.

Conclusions:

• Conserved evolutionary principles govern neuronal biophysics in mammals, relating cell size to ion channel function.
• These principles ensure predictable changes in neuronal integrative properties across species.
• Human cortical neurons exhibit unique biophysical properties, diverging from established mammalian allometric relationships.