Our Senses and Our Brain

Our Senses and Our Brain post page

Teepa Snow

By Teepa SnowFebruary 17th, 2020

Our Senses and Our Brain

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by Teepa Snow, MS, OTR/L, FAOTA


I have opted to offer a video that reinforces the various brain sections that are involved in sensory processing versus writing something out. Check out my hand motions and see if you can use them, and the words, and where I show you on my brain to figure out your own brain sensory connections.

Senses and the Brain Video

What I am going to share out in writing is a different way of talking about our senses, our brain, and our body. I’m going to try and help everyone appreciate two very different ways of looking at sensations and brain function. It so impacts what happens when someone is developing dementia and we are trying to figure out what is going on and how to help.

Taking in and using sensory information can be looked at in two very different and yet important ways. I am going to talk about each of the two ways. It is important to know that we have these two different ways and that they have overlap, and although related, are unique. The two ways I am going to divide things out:

  • Cranial nerves versus spinal nerves
  • Sympathetic versus parasympathetic nerves

These two ways of talking about the nerves in our system are a major reason we function as we do. In infancy through adolescence, we are working to get them under control. As long as we have them working well, we flourish and live well. In combination, these two major groupings of nerve fibers allow us to get sensations into our awareness, knowledge, and skill systems, so we can survive and thrive and appreciate the surroundings in which we live. Traumatic or negative life events, disease, and conditions like dementia can cause these sensory nerve systems to become damaged or dysfunctional, resulting in faulty intake and errors in processing. It is hard to thrive or even survive if sensory nerves are not working as they should and data is misinterpreted or not received at all.

Cranial Nerves – Spinal Nerves

The first division I will cover is, cranial nerves compared to spinal nerves. There are twelve pairs of cranial nerves. There are thirty-one pairs of spinal nerves.

The cranial nerves provide sensation and movement to the head, face, and neck. They also provide us with what are called our special senses: vision, smell, taste, sound, vibration, movement related to gravity and position in space, heart rhythm, respiratory and oxygen intake, digestion, swallowing, sexual arousal, as well as urine and feces storage and release.

The spinal nerves come out of either side of the spinal cord, between the vertebrae, and wrap around the body.  They start right below your skull and are present all the way to your sacrum (tail bone). There is one for each side of the body and the area they cover is called a dermatome. They provide your skin, organs, muscles, bones, and blood vessels in that region, with pressure, temperature, movement, pain, and position awareness. There are sets of motor nerves that match up and are used to do something about the sensations you are getting. The brain and spinal cord are the organizers and controllers of that in-between processing that is so critical to feeling good and doing well.

In dementia, there is not necessarily anything wrong with your spinal nerves. The problems are coming from the organizing and controlling system known as your brain and hence the cranial nerves not working well. As the brain is changed, your ability to get information into the processing system is lost and your ability to know what you are doing and do what you want to do is compromised or missing. When spinal nerves are not active, the body cannot respond and function. Ultimately, it can’t shift weight to keep blood flow going, cover the airway during a swallow of liquid or saliva, relax sphincters so urine and feces can come out when they should or where they should. In other words, the brain is the leader. When the leader leaves town, the work doesn’t happen as it should because the workers don’t know what to do without a leader. That’s frequently when a boss, the other division of nerves I am going to talk about, gets busy and causes trouble. When the thinking is not on the job, the primitive brain can pop in and take over, and not in a good way!

Sympathetic Nerves – Parasympathetic Nerves

The second pairing I am going to talk about is sympathetic nerves compared to parasympathetic nerves. These two systems work together or in opposition to one another. They are part of both the cranial and spinal nervous structures. Both parasympathetic nerves and sympathetic nerves have connections to muscles or wiring that affects pupil size, saliva flow, peristalsis, heart rate, respiration patterns, insulin production and blood sugar levels, bladder function, and bowel function, temperature regulation, blood pressure, reactions to infections or inflammations, arousal and sleep, relaxation or activation of skeletal muscles, pain awareness and management, and the release of a variety of hormones and chemicals into the blood stream though chemical pathways and various glands.

A healthy system is the result of a balance between the sympathetic-parasympathetic nervous systems, they cooperate and collaborate. This allows the person to take in information and respond to it in effective and satisfying ways, while being able to react, if there is a crisis or an emergency situation that requires a quick shift for safety.

In a fully capable and healthy adult, there is a rhythmic shifting from one state to another while the two nerve systems are working in concert and providing the right support at the right time, in response to the incoming sensory data. When the two systems are at odds, the human being will experience distress, discomfort, illness, disability, or immobilization. Because dementia creates so many new experiences and surprises for both the person living with it and the person trying to provide support and help, both people are at risk that their sympathetic and parasympathetic nervous systems will not be able to behave themselves and work together. This reality is a major reason that in PAC, we work on creating time, space, multi-modal cues, and offer support and reflections. We pause and get ourselves to think rather than trying to get data in or get tasks done. We believe that pausing and getting permission, pausing and getting more input, pausing and getting ourselves back together are absolutely essential for the well-being of everyone involved. It just makes neurological sense to get our internal systems under control before we try to help someone else whose internal system is not working well.

Additional Resources

I also want to offer a couple of resources for those of you who do like reading the written word on sensory systems. They come with a twist!

The first article is written by Nicole Day and focuses on the tactile – touch system. She is a woman who works with families and staff who are supporting children with sensory processing issues and autism. She does a nice job of covering the topic and in pointing out some indicators that someone might be having sensory processing issues or tactile defensiveness, which would respond better with an awareness of what is not working well and an effort to modify the environment, interactions, and opportunities. Check out what she offers and see if anything might suggest ideas for people who are challenged in one way or the other with touch and tactile stimulation.

This is a website that focuses on sensory development and issues with children. These two women, Occupational Therapy practitioners, have called their site The Sensory Project. As part of this resource, they have created a large number of podcasts that address a multitude of sensory-related issues. Yes, I realize all of these are designed to address kids. My goal in introducing you to this arena and content area is to encourage all of us to look beyond dementia as brain failure and consider brain dysfunction, when we are struggling, or the people we are trying to help seem to be struggling with what is going on around them. Although, we are just beginning to appreciate possible relationships between issues in brain development with issues in brain deterioration, I believe looking around and checking things out can be helpful in getting additional ways of trying to offer the best options in support and care.

Here is a posting on the cranial nerves, if you want to read more or dig a little deeper.

Here is a posting that covers the subject of spinal nerves and their function in greater depth, if you are interested.

Finally, here is a posting on sympathetic and parasympathetic nerves, if you have interest there. It certainly offers some details on how to possibly help yourself or someone you know who could use a little support, with their permission, of course.


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