[Verse 1]
Naive Hebb just strengthens every connection that fires
Synapses grow wild like untamed desires
Without a ceiling, weights explode to infinity
Need a brake system for stability
BCM brings a sliding threshold that moves
When activity's high, the bar improves
Prevents runaway growth, keeps weights in check
Homeostatic scaling's another spec
[Chorus]
Checkpoints in the neural maze
Three factors guide the plastic ways
Backprop spikes must travel far
Third factor shows us where we are
Sliding thresholds, scaling tight
Makes the Hebbian learning right
[Verse 2]
Somatic spike births at the cell body core
But distal synapses need to know the score
Backpropagating action potential rides
Through dendrites like waves on neural tides
Calcium channels open as it flows
Tells distant synapses what the soma knows
Without this signal crossing the divide
STDP would work with hands tied
[Chorus]
Checkpoints in the neural maze
Three factors guide the plastic ways
Backprop spikes must travel far
Third factor shows us where we are
Sliding thresholds, scaling tight
Makes the Hebbian learning right
[Bridge]
Two-factor learning's trapped in correlation
Pre-post timing without modulation
Dopamine arrives as factor three
Rewards and punishments set learning free
Neuromodulators paint the scene
Tell synapses what experiences mean
[Verse 3]
STDP alone can't read the context clues
Can't tell good timing from the bad news
Third factor broadcasts global information
Reward prediction error's calculation
Eligibility traces hold the gate
While modulators decide synaptic fate
Three-factor rule unlocks the learning code
Transforms correlation to reward
[Verse 4]
Meta-plasticity adds another layer deep
Changes how the changes themselves keep
LTP and LTD dance their ancient song
But checkpoints decide when they belong
Calcium thresholds set the plastic stage
Different levels turn a different page
Low concentrations lead to depression's call
High calcium makes the synapses tall
[Chorus]
Checkpoints in the neural maze
Three factors guide the plastic ways
Backprop spikes must travel far
Third factor shows us where we are
Sliding thresholds, scaling tight
Makes the Hebbian learning right
[Outro]
From Hebb's simple rule to complex computation
Checkpoints guide neural transformation
BCM and scaling, bAP propagation
Third factor brings reward integration
[Final Chorus]
Checkpoints in the neural maze
Three factors guide the plastic ways
Learning's dance with precision starts
When checkpoints guard the neural arts