The illuminated circle in the throat = communication
We know Tool is interested in the theories of chakra energy, so:
Vishuddha (also Vishuddhi) or the throat chakra may be envisioned as relating to communication and growth, growth being a form of expression. This chakra is paralleled to the thyroid, a gland that is also in the throat and which produces thyroid hormone, responsible for growth and maturation. Symbolised by a lotus with sixteen petals.
Thus the reason for the that illuminated circle in the throat region during the artwork progression. This appears to relate to the entire album as a whole, but especially the songs Schism and The Grudge.
__________________ Curiosity is compassion
"You must be the change you wish to see in the world." -- Gandhi