Input-specific critical periods for experience-dependent plasticity in layer 2/3 pyramidal neurons

Area of Science:

• Neuroscience
• Developmental Neuroscience
• Synaptic Plasticity

Background:

• Critical periods for experience-dependent plasticity are known in sensory cortex.
• Altered sensory input can drive neuronal firing rate changes across brain areas.

Purpose of the Study:

• To investigate experience-dependent synaptic plasticity in mouse primary somatosensory cortex.
• To determine if plasticity exhibits input-specific critical periods in layer 2/3 pyramidal neurons.

Main Methods:

• Single whisker experience (SWE) was used to induce synaptic strengthening.
• Electrophysiological recordings were performed on layer 2/3 pyramidal neurons.
• Timing and mechanisms of plasticity at layer 4-2/3 and layer 2/3-2/3 synapses were analyzed.

Main Results:

• SWE triggered glutamatergic synaptic strengthening onto layer 2/3 neurons during a specific postnatal window.
• Both layer 4 and layer 2/3 inputs showed a critical period for SWE-triggered plasticity.
• The critical period timing was delayed and prolonged for layer 2/3-2/3 inputs compared to layer 4-2/3 inputs.
• Plasticity at layer 2/3 inputs did not involve calcium-permeable AMPA receptors, unlike at layer 4 inputs.

Conclusions:

• Synaptic plasticity in the somatosensory cortex exhibits input-specific critical periods.
• The timing and mechanisms of critical periods differ between distinct synaptic inputs.
• This suggests specific developmental regulation of plasticity in vivo.