Dendrite-Specific Amplification of Weak Synaptic Input during Network Activity In Vivo

Area of Science:

• Neuroscience
• Computational Neuroscience
• Cellular Neuroscience

Background:

• Cortical pyramidal neurons receive excitatory synaptic input via apical and basal dendrites.
• Integration of dendritic inputs occurs during network activity, but its effect on segregated inputs is unclear.

Purpose of the Study:

• To investigate how network activity modulates apical versus basal dendritic synaptic input integration in cortical pyramidal neurons.

Main Methods:

• Subcellular two-photon stimulation of Channelrhodopsin2-expressing neurons.
• Nucleus-specific thalamic optogenetic stimulation.
• Paired recordings in somatosensory cortex.
• Intracellular pharmacology and mathematical modeling.

Main Results:

• Slow, depolarized network activity amplifies small-amplitude basal dendritic inputs.
• Network activity reduces the amplitude of all apical dendritic and somatic inputs.
• Postsynaptic voltage-gated channels mediate the amplification of weak basal inputs.

Conclusions:

• Network activity dynamically reconfigures the relative somatic contribution of apical and basal inputs.
• This reconfiguration may enhance the detectability of weak synaptic inputs.
• Voltage-gated channels play a key role in modulating synaptic integration during network activity.