[Verse 1] In the visual cortex, two pioneers found Different types of neurons, vision-processing bound Hubel and Wiesel mapped the neural terrain Simple cells first, let me now explain They love edges and bars in one direction At precise positions, no room for correction Gabor filters model how they operate Gaussian envelope with sine waves ornate [Chorus] Simple cells detect, complex cells collect Filter then pool, that's the architect ON and OFF regions, side by side aligned Position matters to the simple mind But complex cells don't care where you place it Phase invariant, they'll never waste it Filter then pool, the motif so true CNNs copied what biology knew [Verse 2] Simple cells have regions, ON and OFF domains Laid out side by side like railroad trains Move that stimulus just a tiny bit Phase-sensitive response will quickly quit LGN center-surround inputs combine Creating orientation preference so fine Like aligned spotlights in formation Building edge detection across the nation [Chorus] Simple cells detect, complex cells collect Filter then pool, that's the architect ON and OFF regions, side by side aligned Position matters to the simple mind But complex cells don't care where you place it Phase invariant, they'll never waste it Filter then pool, the motif so true CNNs copied what biology knew [Verse 3] Complex cells take a different approach Same orientation, broader scope coach Position invariant across their field Bar can wander, they'll never yield Energy model explains their trick Square and sum, the math's not thick Quadrature simple cells pooled together Building invariance, smart and clever [Verse 4] From cat experiments to monkey sight Recording electrodes revealed the light Orientation columns, pinwheel arrays Hypercolumns mapping visual space for days Nobel Prize winners showed us the way How cortical circuits process and display The building blocks of what we see Visual hierarchy's first degree [Bridge] From the Neocognitron to modern day Convolutional networks learned the way Max pooling, average pooling too All inspired by what these neurons do Biological blueprint, engineered design V1's architecture, perfectly refined [Chorus] Simple cells detect, complex cells collect Filter then pool, that's the architect ON and OFF regions, side by side aligned Position matters to the simple mind But complex cells don't care where you place it Phase invariant, they'll never waste it Filter then pool, the motif so true CNNs copied what biology knew [Outro] Two cell types in the cortical dance Hubel and Wiesel gave us the chance To understand how vision starts to grow From simple features to complex show
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