How many neural processes are going on within your body as you read this sentence? The answer to this question is hard to fathom, I know, but give it a shot. Try to imagine all the physiological events that are being controlled by your nervous system at this very moment. Our nervous systems control a dizzying array of sensory, motor, and cognitive processes simultaneously, without us granting them “permission” to do so. In fact, most of our neural functions require no mental energy on our part whatsoever! For this reason, it is extremely easy to take these basic processes for granted. However, if we were to witness the suffering of an individual with multiple sclerosis, we might begin to appreciate these things a little more.
In Juan’s most recent post, “Making New Blood Vessels Helps Neuronal Recovery,” he briefly mentioned a mouse model of the human disease, multiple sclerosis (MS). MS is classified as an inflammatory autoimmune disease wherein the immune system launches an attack on the myelin-producing glial cells (oligodendrocytes) of the central nervous system. This can cause a myriad of neurological symptoms including visual problems, muscle weakness, difficulties with coordination and balance, and forms of emotional dysfunction like depression. The primary thing that all of these processes share is their dependence on fast and reliable communication between neurons. To achieve this, the axons of neurons are wrapped in myelin, a dielectric material that insulates the axon and allows electrical impulses to travel more quickly through a process called saltatory conduction. When the myelin is degraded and the insulation is lost, as in the case of MS, neurons lose their ability to communicate efficiently and can begin to degenerate.
My point in describing this devastating disease is not to make you worried about developing the disease one day. Instead, I wish to call your attention to an interesting aspect of nervous system function that I feel receives too little attention. Neurons are complex cells and receive the bulk of our attention, perhaps rightfully so, but consider how much less interesting they would be without their myelin-producing counterparts, oligodendrocytes. If these glial cells weren’t “around” the neurons to promote speedy transmission, we wouldn’t be able to ponder all the topics discussed in this blog because higher-order cognition would be impossible. It is thanks to the synergism between neurons and glia that the nervous system is capable of all the amazing processes we love to discuss!