Increased glutamatergic synaptic transmission during development in layer II/III mouse motor cortex pyramidal neurons

Postnatal maturation of the motor cortex is vital to developing a variety of functions, including the capacity for motor learning. The first postnatal weeks involve many neuronal and synaptic changes, which differ by region and layer, likely due to different functions and needs during development. Motor cortex layer II/III is critical to receiving and integrating inputs from somatosensory cortex and generating attentional signals that are important in motor learning and planning. Here, we examined the neuronal and synaptic changes occurring in layer II/III pyramidal neurons of the mouse motor cortex from the neonatal (postnatal day 10) to young adult (postnatal day 30) period, using a combination of electrophysiology and biochemical measures of glutamatergic receptor subunits. There are several changes between p10 and p30 in these neurons, including increased dendritic branching, neuronal excitability, glutamatergic synapse number and synaptic transmission. These changes are critical to ongoing plasticity and capacity for motor learning during development. Understanding these changes will help inform future studies examining the impact of early-life injury and experiences on motor learning and development capacity.

Automated summary

Postnatal maturation of the motor cortex is vital for developing motor learning capacity. During the first few weeks after birth, there are numerous neuronal and synaptic changes in the motor cortex, which vary by region and layer, likely due to different developmental functions and needs. Layer II/III of the motor cortex plays a crucial role in receiving and integrating inputs and generating attentional signals for motor learning and planning. By studying the changes in layer II/III pyramidal neurons of the mouse motor cortex from neonatal to young adult stages, we found several changes including increased dendritic branching, neuronal excitability, glutamatergic synapse number, and synaptic transmission. These changes are crucial for ongoing plasticity and motor learning capacity during development. Understanding these changes can help inform future studies on the impact of early-life injury and experiences on motor learning and development capacity.