Structural and Functional Maturation of Rat Primary Motor Cortex Layer V Neurons

The study investigates how neurons in the rat motor cortex develop after birth. It focuses on the axon initial segment (AIS), a critical part of the neuron that initiates electrical signals. The researchers explore how the size and structure of the AIS change as the neurons mature. The study found that as neurons grow, their AIS elongates, which is connected to how well the neurons can send electrical signals. This elongation is most prominent in the first few weeks after birth. Unlike sensory areas, the motor cortex neurons show a continuous process of AIS maturation without distinct phases of remodeling. This maturation helps the neurons adjust their signaling capabilities as they grow larger.

• 1
  Cell growth in the first two postnatal weeks leads to a substantial decline in neuronal input resistance, requiring larger input current for action potential firing.
• 2
  The most prominent AIS elongation and significant maturation of functional output properties occur during the first two postnatal weeks, without alternating phases of AIS plasticity.
• 3
  From the third postnatal week up to five months, cell growth, AIS elongation, and functional output maturation were marginal, indicating early stabilization.