We all learned a long time ago that nerves carry impulses from the brain to parts of the body so that those parts do the things the brain tells them to do. But HOW does that actually happen? Get ready to be amazed, because this is super cool.
Nerves are a class of cells whose only job is to carry instructions from the brain to the body, or to other parts of the brain. I won't get too much into the structure of nerve cells right now, but I'll definitely come back around to that in a future blog. Today we'll just concentrate on how those messages get passed along.
Nerve impulses always move in one direction, from nucleus end of the cell and down the appendage of the nerve, called the axon. Nerve impulses also tend to move in three basic paths:
Nerve impulses can move from one area of the brain to another. We often call these "synapses," but really every nerve transmission is a synapse.
Messages can move from the brain to the body, called "efferent" transmissions. I memorized this by thinking of the first letter as E for Exit, as in messages exiting the brain. These kinds of synapses are usually motor signals telling the body to do something.
Messages can also move from the body to the brain, called "afferent" transmissions. I memorized this one by thinking of them as messages going Aboard the brain. Not as slick as my other mnemonic! These kinds of synapses are almost always sensory, giving the brain surveillance information about what's happening in the body.
Here's the part where I get excited because it's just so nifty.
Nerves don't actually touch each other! So how do they get the messages from one nerve to the next??
It's way more complicated than what I'm going to say here, but inside the nerve, the signal gets picked up from the dendrites, the hair-looking things that are surrounding the nucleus in the image above. The message then turns into an electrical signal (super simplified) that the nucleus interprets and then passes down along the axon, traveling in the myelin sheath that surrounds the axon. The message then gets to the axon terminals, which are the finger-like appendages that come off the end of the axon. THEN the axon terminals turn the electrical message into a chemical, and those chemicals have to jump over the gap between the terminals and the dendrites of the next nerve. That gap is called the synaptic gap or synaptic cleft, depending on which textbook you're reading. Think Trinity at the beginning of The Matrix when she and the cops are jumping from building to building in the opening chase scene. Then the chemicals are intercepted by the dendrites of the next nerve, turned into electrical signals, and the process continues until the message reaches the end point.
Is anybody else as amazed and excited as I am?? Because I think it's super cool how the nerves actually work.
Now, when it comes to singing in particular, those nerve impulses can transmit all kinds of messages from the brain to control things like vibrato, pitch, dynamics, and well, everything else. All singing begins in the brain, after all. But because singing is such a complex activity, and voicing in general is something we learn to do and execute early on, there seems to be evidence that the brain doesn't really micro-manage how it works. Instead, there is evidence that the brain kind of gives a general instruction, "Hey, sing this thing," and sends out a general message down the Vagus nerve to the larynx, and the laryngeal muscles are then left to their own devices to interpret that general message and execute the directive. The brain is a super powerful and very busy structure, and doesn't necessarily need to articulate every tiny detail of voicing, so the voice does the work of making the minutiae happen.
Of course, there are things that can affect nerve transmission from simple glitches to debilitating nerve dysfunction, and everything in between. Most of the time our clients aren't going to have to deal with declining nerve function until later in life when that happens as a natural, but frustrating, part of aging. However, if you have a client with a known nerve transmission issue, it can be helpful to understand how the nerves work so that you can know what is under their control as a singer, and where you need to have grace and adapt. There may be things you can do to help singers with differences in nerve function sing better, and there might be times when you need to help your client celebrate and accept the voice they have. Understanding nerve function can help you know which path is the right one to take.
If you have questions about nerve function and singing, there are some excellent resources out there. Of course, you can hop on my email list to get information like this (plus a little extra that doesn't get shared on the socials) delivered right to your inbox every week. I'd also highly recommend following along with two of my colleagues, Meredith Colby of the Neuro-Vocal Method, and Heidi Moss, who hosts Minding the Gap on Facebook, a group looking at the neuroscience of singing. There's so much out there to learn! We'll never get bored. Happy learning!