Differential signaling to subplate neurons by spatially specific silent synapses in developing auditory cortex

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Cortical Development

Background:

• Subplate neurons (SPNs) are critical for early cerebral cortex development.
• SPNs receive thalamic inputs and excitatory inputs from the developing cortical plate.
• Silent (non-AMPAR-mediated) excitatory synapses can precede functional synapses during development.

Purpose of the Study:

• To investigate the spatial origin of silent and AMPAR-mediated synapses onto SPNs.
• To determine if silent and functional synapses originate from different cortical layers.
• To explore the functional implications of distinct synaptic inputs on SPN development.

Main Methods:

• Used laser-scanning photostimulation in acute thalamocortical slices of mouse auditory cortex.
• Studied synaptic inputs onto SPNs during the first two postnatal weeks.
• Analyzed the spatial origins of both silent and AMPAR-mediated synapses.

Main Results:

• Identified silent synapses originating from the cortical plate onto SPNs.
• Demonstrated that silent and functional synapses arise from different cortical locations.
• Showed that SPNs can be classified based on the spatial patterns of these synaptic inputs.
• Revealed that SPNs can integrate thalamic input with spontaneous cortical activity.

Conclusions:

• SPNs receive spatially segregated silent and functional synaptic inputs during development.
• Distinct populations of cortical neurons signal to SPNs based on developmental stage and activity.
• SPNs play a crucial role in integrating ascending thalamic and spontaneous cortical activity.
• These findings highlight SPNs' integral role in developing intracortical circuitry and sculpting thalamocortical connections.