system
Given the following post, respond as if you're commenting on Reddit:
human
If I move both my index fingers at once, am I sending one signal to both hands, or am I sending 2 individual signals? Is there a signal queue?
gpt
Lots of signals!

How are you moving your index finger? Just a quick movement and then stop? Sustained goal-tracking? Sustained proximal extension?

There is a swirl of signals operating between prefrontal cortex (probably both sides), supplementary motor cortex (probably both sides) and primary motor cortex (primarily contralateral to the moved finger); as well as between cortex, brainstem, cerebellum, thalamus, and back to cortex; and between cortex, basal ganglia, thalamus, and cortex. These are all for smoothing movements, planning movements, etc.

The final pathway is a series of pulses down the corticospinal tracts to alpha motoneurons in your spine, which send pulses directly to muscle fibers in your forearm and hand. Depending on how much effort you need, there may be more or fewer groups of muscle fibers contracting, and at different rates. The rates are governed by the spiking rate in the alpha motoneurons and the groups are governed by the activation pattern in the cortex and the spine.

With sustained effort, there will be a feedback loop set up with additional spike trains sent by intrafusal muscle cells and bag fibers both to the motoneurons and up the dorsal columns to the thalamus and the cortex to help regulate the muscle firing rate. If you're looking at your finger, that information can also be used as feedback. So now there's visual processing and flows from association visual cortex to prefrontal cortex.

There's no queue. Neurons send spikes, or *action potentials*, at varying rates. They code for responses by the rate of spiking or sometimes by the timing of spikes. Spikes propagate from neuron to neuron by the release of neurotransmitters across small fluid gaps (the synapses). Of course spike trains can also lead to inhibition, setting a gate to interrupt spike propagation from other cells (analogous to a transistor); or they can cause changes in gene expression altering the properties of the target neuron (analogous to resetting circuit props in an FPGA).

So if you're extending both index fingers, you have bilateral corticospinal tract signalling, bilateral dorsal column signalling, and bilateral intraspinal, cerebellar, basal ganglionic, thalamic, visual, and prefrontal signalling.