Large-scale synaptic dynamics drive the reconstruction of binocular circuits in mouse visual cortex

Area of Science:

• Neuroscience
• Developmental Biology
• Synaptic Plasticity

Background:

• Visual experience shapes neuronal responses in the primary visual cortex during a critical developmental period.
• The synaptic mechanisms underlying binocular circuit formation remain largely unknown.

Purpose of the Study:

• To investigate the synaptic changes and neuronal dynamics in the mouse binocular visual cortex during postnatal development.
• To elucidate the mechanisms responsible for the formation and organization of binocular circuits.

Main Methods:

• Chronic in vivo two-photon imaging of layer 2/3 neurons in the mouse binocular visual cortex.
• Recording of neuronal somata and excitatory synaptic inputs onto dendritic spines.
• Analysis of spine turnover, visual response remapping, and synaptic activity.

Main Results:

• Significant spine turnover and eye-specific remapping of visual responses occurred during the critical period.
• Spine retention was correlated with calcium activity, especially in response to the neuron's preferred visual stimulus.
• Synaptic responses became more correlated with neighboring neurons post-development.

Conclusions:

• Individual synapses exhibit dynamic changes, including turnover and activity-dependent retention.
• Hebbian and heterosynaptic mechanisms likely drive synaptic input organization and binocular circuit development.
• These findings highlight fundamental synaptic mechanisms shaping visual cortical neuron development.