[Verse 1] Wilder Penfield, scalpel and probe, touched the brain while the patient spoke, every twitch mapped skin to scalp, a twisted little homunculus unrolled. Lips as big as both his hands, torso shrunk to a narrow band, nineteen thirty-seven, electrode by electrode, he drew the body as the cortex coded. [Chorus] Column by column, Mountcastle found it true, one neuron's whisker, one neuron's touch, stacked like coins in cortical rows, modality keeps to the lane it knows. Map it, probe it, feel where it goes, S1's the mirror the body only almost knows. [Verse 2] Fifty-seven, cat and monkey hide, vertical columns side by side, a cooling touch, a pressure deep, each layer answers the same stimulus beat. Slow-adapting or quick to fade, Merkel and Meissner, each one stayed inside its column, never crossing the line, the founding proof that the cortex is designed. [Chorus] Column by column, Mountcastle found it true, one neuron's whisker, one neuron's touch, stacked like coins in cortical rows, modality keeps to the lane it knows. Map it, probe it, feel where it goes, S1's the mirror the body only almost knows. [Verse 3] Sever the median nerve and wait, Merzenich watched the borders migrate, eighty-three, the hand's gone still, neighboring skin comes up the hill. Pons in ninety-one dug further still, decades of silence, a deafferented limb, cheek crept inward, ten to fourteen millimeters wide, the face now answers where the hand once replied. [Verse 4] DiCarlo, Johnson, Hsiao drew the field, area three-b, a center revealed, excitation core with a flickering ring, inhibition lagging, a Gabor-shaped thing, just like simple cells in the visual stream, ripples and edges read along the seam, the skin writes texture in a shifting code, spatial pattern down the afferent road. [Verse 5] Romo buzzed the cortex, no finger required, microstimulation lit the wire, flutter frequency, a pulse the brain believed, three-b fooled into feeling what it perceived. Downstream in SII the memory holds, prefrontal neurons comparing old, is this faster, is this the same, working memory plays the discrimination game. [Bridge] Pei found motion that ignores the shape, area one, direction won't escape, curved or flat, the vector stays true, Lieber and Bensmaia mapped texture's hue, dimensions high, a spectral code so wide, now electrodes borrow what the fingertip supplied, feeding prosthetic hands a synthetic skin, teaching silicon the touch within. [Chorus] Column by column, Mountcastle found it true, one neuron's whisker, one neuron's touch, stacked like coins in cortical rows, modality keeps to the lane it knows. Map it, probe it, feel where it goes, S1's the mirror the body only almost knows. [Outro] Penfield's homunculus, puffy-lipped and strange, Pons' silent cheek still learning to exchange, every column counting, every map rewritten clean, touch is just a story the parietal lobe has seen.
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