[Verse 1] Molecular guidance shows the path, but wiring needs more precision Activity steps up to refine each synaptic transmission In the baby hippocampus, chloride levels run so high NKCC1 pumps it inward while KCC2 stays shy [Chorus] GABA switch, chloride flip, excitation's early game GDPs synchronize the network, calcium stakes its claim Silent synapses await their cue for AMPAfication Hebbian rules guide the refining of each neural conversation [Verse 2] When GABA-A receptors open, chloride rushes out the door Depolarizing immature cells, not inhibiting anymore This paradoxical period lasts from P7 to fourteen KCC2 expression climbing, reversing the chloride scene [Chorus] GABA switch, chloride flip, excitation's early game GDPs synchronize the network, calcium stakes its claim Silent synapses await their cue for AMPAfication Hebbian rules guide the refining of each neural conversation [Bridge] Giant waves of depolarization sweep across the neonatal brain Ben-Ari and Cherubini mapped this developmental domain Coordinated calcium surges validate synaptic bonds While molecular architects laid the foundation, activity responds [Verse 3] Silent synapses hold NMDA but AMPA receptors hide Correlated firing triggers trafficking from the cytoplasmic side GluR1 subunits mobilize when calcium levels spike Transforming mute connections into synapses that strike [Verse 4] Theta oscillations emerge as networks mature their song CA3 drives the rhythm, pulling CA1 along Interneuron populations diversify their inhibitory roles Parvalbumin and somatostatin cells patrol their separate goals Activity sculpts the microcircuit through competitive control [Chorus] GABA switch, chloride flip, excitation's early game GDPs synchronize the network, calcium stakes its claim Silent synapses await their cue for AMPAfication Hebbian rules guide the refining of each neural conversation [Chorus] GABA switch, chloride flip, excitation's early game GDPs synchronize the network, calcium stakes its claim Silent synapses await their cue for AMPAfication Hebbian rules guide the refining of each neural conversation [Outro] Critical periods close when plasticity starts to wane Activity-dependent sculpting of the hippocampal domain
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