Visual Pathway Branchpoints

by Greg Crowther

With a vibe reminiscent of the Clash's "Rock the Casbah," this song covers the flow of visual information through the nervous system into the brain. It focuses on two specific places which may be confusing because they serve as branchpoints, thus sending information in two separate directions.

You have two optic nerves,
And at the junction where they converge,
The right-side field of view goes left,
And the left goes to the right.
These axons synapse thus:
In the superior colliculus,
Or most end at the thalamus,
In its nucleus for sight.

CHORUS:
Branchpoints ... in the optic chiasm.
Branchpoints ... along the optic tract.
Branchpoints ... yes, the visual pathway has 'em,
And when axons reach a branchpoint, there is no turning back!

• karaoke

• sheet music (with melody play-back)

Songs like this one can be used during class meetings and/or in homework assignments. Either way, the song will be most impactful if students DO something with it, as opposed to just listening.

An initial, simple follow-up activity could be to answer the study questions below. A more extensive interaction with the song might entail (A) learning to sing it, using an audio file and/or sheet music as a guide, and/or (B) illustrating it with pictures, bodily poses, and/or bodily movements. The latter activity could begin with students identifying the most important or most challenging content of the song, and deciding how to illustrate that particular content.

(1) Among the cranial nerves, what number is given to the optic nerve?

(2) How are the optic nerve, optic chiasm, and optic tract distinct from one another?

(3) The superior colliculus is mentioned here as part of the visual pathway. What type of information is processed by the INFERIOR colliculus?

(4) What is the name of the "nucleus for sight" in the thalamus?