Let the Movement Through
Asystole

The hand is ready, the cup is near,
Which little movement starts from here?

Cortex sends into the striatum,
Caudate, putamen hear the plan.
Internal pallidum and reticulata
Keep inhibition on the thalamus.
Direct-path striatum quiets that output,
A brake upon a brake lets through.
Thalamus can excite the cortex,
Helping chosen movement through.

Let the movement through,
Direct can lift the brake for you.
Indirect can turn that braking up,
Shape the choice before we lift the cup.
D one helps the direct path,
D two quiets the indirect.
Dopamine supports the movement,
Hold the net effect in your head.

Indirect striatum quiets
The external pallidum's tone.
Subthalamic cells are freed,
Their excitatory signal grows.
They drive the output brake up higher,
The thalamus gets less room to sing.
Midbrain dopamine neurons send
Their signals to this balancing.
These are loops that shape selection,
A working sketch of a deeper dance.

Let the movement through,
Direct can lift the brake for you.
Indirect can turn that braking up,
Shape the choice before we lift the cup.
D one helps the direct path,
D two quiets the indirect.
Dopamine supports the movement,
Hold the net effect in your head.

Parkinson's loses these dopamine cells;
Movement slows, rigidity may come.
A resting tremor can join the picture,
Each person's pattern has its own.
Huntington's, expanded C A G,
Striatal damage, chorea may appear.
One altered gene can pass it onward;
Thinking and mood need care here.
Subthalamic damage can bring
Flinging limbs on the opposite side.
We learn the circuits, learn the pattern,
And keep the person in our sight.

Let the movement through,
Direct can lift the brake for you.
Indirect can turn that braking up,
Shape the choice before we lift the cup.
D one helps the direct path,
D two quiets the indirect.
Dopamine supports the movement,
Hold the net effect in your head.

You move the cup and make some room,
The lamp is warm; we're learning too.