[Verse 1] Behind the brain where the hemispheres meet, the splenium's a cable, a posterior street, Hofer and Frahm traced the wire back in oh-six, parietal fingers crossing, no political tricks. Area five, area seven, the sulcus called IPS, they mirror their twin like a postcard address, homotopic mostly, a few heterotopic strays, same address, different hemisphere, same relay. [Chorus] Cross the splenium, mirror the map, five, seven, IPS close the gap, but the fingertip zone stays home alone, three-b's acallosal, it's wired on its own, cut the bridge and the left side goes dim, Kinsbourne's seesaw tips on a whim. [Verse 2] Touch your thumb, touch your pinky, feel the data stay put, area three-b's hand map keeps its own foot, distal digits don't cross over, they're local-grown news, while shoulder and trunk fibers ride the splenium cruise. Kinsbourne said attention's a rivalry, a tug-of-war of eyes, each hemisphere pulling for the opposite prize, sever that cable and the balance goes wrong, Lunven, twenty-fifteen, found the damage prolonged, posterior callosum broken, neglect lingers on. [Chorus] Cross the splenium, mirror the map, five, seven, IPS close the gap, but the fingertip zone stays home alone, three-b's acallosal, it's wired on its own, cut the bridge and the left side goes dim, Kinsbourne's seesaw tips on a whim. [Verse 3] Now follow the cingulum, a ring beneath the dome, precuneus and posterior cingulate calling home, to parahippocampal fields and entorhinal gate, Mufson and Pandya mapped it in eighty-four, right on the plate, Jones and colleagues checked it, twenty-thirteen review, medial prefrontal cortex joins the rendezvous, this is the cable of the default-mode choir, humming while you're resting, never going quiet. [Verse 4] Retrosplenial station, Brodmann twenty-nine and thirty too, takes the medial parietal whisper and pushes it through, down to the hippocampus, building scenes and routes, the compass in your mind that never shouts or doubts, lose this tract and wandering turns into a maze, precuneus and memory chapters cross back through these ways. [Bridge] Two systems, one story, lateral speaks to lateral, medial loops with medial, nothing here's incidental, splenium for the body, cingulum for the past, two white-matter rivers keep the cortex vast. [Chorus] Cross the splenium, mirror the map, five, seven, IPS close the gap, but the fingertip zone stays home alone, three-b's acallosal, it's wired on its own, follow the cingulum, precuneus to the past, retrosplenial keeps the memory map intact. [Outro] Splenium, cingulum, two tracts, one truth, the parietal lobe wiring every proof, mirror and memory, balance and scene, that's the callosal, cingulate machine.
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