Visual experience regulates the development of long-term synaptic modifications induced by low-frequency stimulation...

Area of Science:

• Neuroscience
• Synaptic Plasticity
• Developmental Neuroscience

Background:

• Visual experience shapes visual cortical neuron responses throughout life, with greater plasticity during critical periods.
• Previous work showed T-type calcium channel-dependent long-term potentiation (LTP) in the critical period visual cortex.
• This study explores synaptic plasticity induction in adult mouse visual cortex.

Purpose of the Study:

• To investigate if low-frequency stimulation can induce synaptic plasticity in adult mice.
• To compare the mechanisms of LTP in adult versus critical period visual cortex.
• To understand the role of calcium channels and GABAergic inhibition in developmental changes of synaptic plasticity.

Main Methods:

• Extracellular field potentials in mouse visual cortex layer 2/3 were evoked by layer 4 stimulation.
• Low-frequency (2Hz) stimulation was applied to induce LTP.
• Pharmacological antagonists for T-type and L-type calcium channels were used.
• GABA-A receptors were blocked using pharmacological agents.
• Dark rearing was employed to assess the impact of visual experience.

Main Results:

• 2Hz stimulation induced LTP in adult mice, similar to the critical period.
• Adult LTP was dependent on L-type calcium channels, while critical period LTP depended on T-type channels.
• This developmental shift in LTP mechanism was prevented by dark rearing.
• T-type channel-dependent LTP occurred without GABA-A receptor blockade, while L-type channel-dependent LTP did not.

Conclusions:

• Synaptic plasticity mechanisms in the visual cortex undergo developmental changes.
• Different forms of synaptic plasticity, mediated by distinct calcium channels, contribute to experience-dependent visual response modification in critical periods and adulthood.
• These findings highlight the dynamic nature of neural circuit refinement throughout life.