As we’ve discussed on this blog before, there are many, many ways to stimulate nerves through receptors. Sensory input includes vestibular signals, sight, sound, smell, taste, and touch. For each of the senses, the corresponding sensory organ (eyes, ears, nose, etc.) is equipped with electric transducers that transform physical or chemical signals into electrical signals, allowing the brain to function.
Our Functional Neurologists use sensory input to stimulate certain parts of the brain, thus rebuilding or strengthening neural pathways. For example, as we discussed in a previous blog, we can use light therapy or eye-tracking exercises to stimulate the occipital lobe, improving its function. However, what can we do for a client who is blind? Since there is no way of providing sensory input, our usual therapies wouldn’t work for people who lack skin sensitivity, are deaf, or have no sense of smell or taste.
In cases like these (and in others), our Functional Neurologists employ direct electric stimulation.
The use of electric stimulation in neuroscience is not new—it’s been used by doctors and researchers since the early 1950s. Physical therapists commonly used it for pain relief and to reduce muscle contraction in certain muscle groups. The practice became known as Transcutaneous Electric Nerve Stimulation, or TENS.
However, not all forms of electric stimulation are created equal.
Many doctors employ invasive electrical stimulation for patients who have disorders that do not respond to medication or therapy. Invasive measures use an electrode that is surgically placed on a specific area of the brain. The electrode is attached to an exterior, battery-powered control pack that the patient is able to switch on and off. This allows the patient to stimulate injured parts of their brain. For patients with dystonia, Parkinson’s, or other neurological movement disorders, this arrangement allows them to eliminate or reduce symptoms (e.g. tremors).
However, invasive methods do have risks. Even under the best circumstances, brain surgery can result in infection or death. In other cases, the electrode might be ineffective—rendering the surgery useless.
Non-invasive nerve stimulation, however, can accomplish the same thing without surgery. The secret to electrical nerve stimulation is found in neuron depolarization.
To understand how neuron depolarization helps stimulate nerves without using receptors, you’ll need a basic understanding of how a nerve transmits electricity in the first place. Nervous system cells contain ions, or charged particles. The inside of a nervous system cell is negatively charged, while the outside is positively charged. This creates a concentration gradient.
Like most things in nature, the negative and positive ions want to create balance and neutralize the gradient (with negative ions going outside the cell and positive ions going inside the cell). This creates what is called electrical potential, or the potential of ion movement from one area to another.
However, the membrane of the nerve cell keeps this from happening. The only way for a nerve cell to allow the passage of ions is when the nerve is stimulated. This opens the membrane and allows the concentration gradient to balance. Stimulation of the nerve creates an electrical potential that travels up the neural chain, stimulating the brain. This normally happens when a receptor receives a physical or chemical signal, which is then transduced into an electrical signal to travel up the nervous system.
Because we know this, our Functional Neurologists can use electrical stimulation to manipulate nerves rather than depending on sensory signals. While many patients fear the use of electricity at first, only a very low amplitude of electricity is required to stimulate the nerves. As a result, it’s very safe—at the very least, it represents far less risk to patients than brain surgery.
At the University of Wisconsin, researchers have developed a device to test the capabilities of electrical nerve stimulation. Their invention, known as the Pons Device, employs a series of electrodes placed on the tongue. Researchers use the electrodes to stimulate different nerves in the tongue (which we covered in our blog on the sense of taste). The device has been known to help correct movement disorders, balance issues, cognition problems, and other areas of neurological function.
Dr. Carrick, the neuroscientist who developed the therapies we use at Plasticity Brain Centers, has been doing this type of rehabilitation for more than 20 years. Plasticity Brain Centers utilizes nerve stimulation in a similar fashion. In our sessions, we have employed electrodes on the wrists, tongues, faces, and legs of our patients. Each nerve represents differently in the brain, allowing us to precisely target which areas we stimulate.
One of the uses we’ve found for electrical stimulation is for clients who have trouble walking. Nerve damage or damage in the brain can make mobility a challenge for recovering patients. Even when legs are fully functional, neural impulses between the legs and the brain may not be strong enough for walking.
When that’s the case, our Functional Neurologists place electrodes on specific parts of the leg. We then ask the client to push their foot in a certain direction while we stimulate the electrodes in a pattern that mimics walking. This sends the brain “walking” signals, strengthening the neural pathways that allow walking to occur. By repeatedly exercising and stimulating the brain this way, we have been able to help patients regain the ability to walk normally.
In other cases, a damaged nerve or a damaged parietal lobe can cause the brain to lose awareness of a body part. Lack of perception leads to lack of sensory input, which inhibits the function and movement of the body. Even if a nerve is healed, the body part may not be accurately represented in the brain. We can apply electrical stimulation to the damaged nerve, asking the client to move the body part while we apply electricity.
As a result, the neural pathways that facilitate movement are strengthened, allowing the body part to be accurately represented in the brain. In addition, the use of visual stimulus (looking at the body part) and the electrical stimulus at the same time is an example of spatial summation, which we discussed in last week’s blog.
In one of our earliest blogs, we discussed the brain’s primary purpose. It has three components:
●To perceive the body’s sensory signals
●To interpret signals from the body
●To respond appropriately for survival
Perceiving the body’s signals is the foundation of this process—without perception, there is no interpretation. Without interpretation, an appropriate response is impossible. If the sensory organs are damaged (making perception impossible), then non-invasive nerve stimulation can allow our functional neurologists to skip receptors altogether and rehabilitate the brain through nerve conduction.
Even in cases where receptors are working correctly, electrical nerve stimulation provides neurologists with another therapy modality to use in conjunction with ReceptorBased® rehabilitation. Direct stimulation of the nerves is not only safer than invasive modes of Deep Brain Stimulation—it allows our powerful therapies to work on patients with all types of limitations: blindness, deafness, lack of skin sensation, and more.