[Verse 1]
Close your eyes, reach for the cup on the shelf,
your brain writes the order before you feel yourself—
that's the inverse model, counting out the force,
target first, command second, cause before the course.
It asks what signal gets this hand to the jar,
solving it backward, quiet, like steering by a star.
[Chorus]
Modèle inverse, modèle en avant—
inverse builds the order, forward tells what's coming next.
C'est la copie, l'efférence qui prédit,
a whisper to the brain before you move an inch.
Deux modèles, une danse en toi,
inverse et forward, ça marche comme ça.
[Verse 2]
Nineteen-fifty, von Holst had a hunch,
Mittelstaedt beside him, testing a fly's lunch—
when the fly moves itself, the world stays calm and still,
but twist its eye by hand, it panics, swerves uphill.
The brain sends a copy, a shadow of the call,
corollary discharge, cancelling it all,
predicting what the senses ought to feel and see,
so self-made motion never fools the referee.
[Chorus]
Modèle inverse, modèle en avant—
inverse builds the order, forward tells what's coming next.
C'est la copie, l'efférence qui prédit,
a whisper to the brain before you move an inch.
Deux modèles, une danse en toi,
inverse et forward, ça marche comme ça.
[Verse 3]
Try to tickle your own palm, go on, give it a go—
no giggle, no shiver, no ticklish undertow,
because your forward model already knew the touch,
Blakemore, Wolpert, and Frith proved exactly this and such,
ninety-eight, the sensation gets cancelled at the source,
a stranger's hand surprises you — your own hand, of course, cannot.
[Verse 4]
Cerebellum's the hideout, the forward model's den,
tucked below the cortex, predicting again and again,
while parietal cortex plays referee and sage,
blending guess with feedback to build the body's gauge—
that blend is called state estimation, where you are right now,
not where you were a moment back, but here, somehow.
[Bridge]
Throw a dart that misses, the model learns, adapts,
optimal feedback control keeps patching up the gaps,
inverse and forward, partners rewriting the plan,
chaque erreur, une leçon, learning all it can.
Apprendre, s'ajuster — the brain revises its guess,
nothing wasted, mon ami, not even a mess.
[Chorus]
Modèle inverse, modèle en avant—
inverse builds the order, forward tells what's coming next.
C'est la copie, l'efférence qui prédit,
a whisper to the brain before you move an inch.
Deux modèles, une danse en toi,
inverse et forward, ça marche comme ça.
[Outro]
Command et prédiction, moving hand in hand,
c'est la copie qui te sauve du chatouillement,
deux modèles, un cerveau — comprends maintenant,
inverse, forward, ça marche comme ça, comme ça.