Evidence for structural and functional changes of subplate neurons in developing rat barrel cortex

Area of Science:

• Neuroscience
• Developmental Biology
• Sensory Cortex Development

Background:

• The subplate acts as a transient relay in the developing sensory cortex, crucial for thalamocortical projection formation.
• Subplate neuron (SPn) activity diminishes after the thalamus-layer IV connection is established.

Purpose of the Study:

• To investigate the mechanisms behind the decline in subplate activity during early postnatal development.
• To examine developmental changes in rat somatosensory cortex subplate neurons before and after thalamocortical connection establishment.

Main Methods:

• Electrophysiological recordings to assess SPn firing patterns and membrane properties.
• Analysis of synaptic transmission using paired-pulse ratios and MK-801 blocking rates.
• Morphological analysis of SPn soma size, dendritic complexity, and pruning processes.

Main Results:

• SPns exhibited increased regular-spiking patterns and membrane property maturation.
• Neuronal excitability decreased, indicated by increased rheobase and shifted frequency-current curves.
• Reduced presynaptic transmitter release and significant dendritic pruning were observed after day 10.

Conclusions:

• The decline in SPn activity is attributed to reduced neuronal excitability, synaptic transmission, and dendritic complexity.
• These changes correlate with the establishment of the thalamocortical pathway and reduced subplate functional connectivity.