Sunday 19th February 2017,
The Liz Army

Our sixth sense: a lesson on proprioception

When I was reading My Stroke of Insight by Dr. Jill Bolte Taylor, she said no self-respecting neuro-scientist would allow a surgeon into their brain. I believe she was alluding to how important this organ is to our functioning and overall sense of self.

After my first brain surgery I did not notice anything different about my functioning (other than being tired–which is to be expected for the first few months to years after such a grueling order). But before the second surgery, I was cautioned and warned by my neurosurgeon that the surgery would impair me to some extent. He couldn’t tell me how I would feel when I woke, just that there would be a deficit.

Brain surgery and its lasting effect depends upon where your tumor is located. Some people have “non-operable” tumors because the mass is buried in an area too deep to reach safely, or too close to an area that would impair a person’s quality of life.

My tumor is in the parietal lobe (pictured above) near the sensory and motor strips. As my neurologist Dr. P once said, this area isn’t “too juicy.” What I think he meant was that if part of the lobe was damaged at least I wouldn’t lose my personality or ability to reason, or the multitude of other traits associated with the frontal lobes (with which most of our higher functioning is based).

Sorry if I am losing anyone. I’m getting to a point…

When I had my second brain surgery I felt different when I woke up. My brain damage is minor and is completely characteristic of a person who has impairment in the parietal lobe and sensory strip of the brain. This damage is minor, and now, more than year later, I am very used to my “new brain.”

However, it has been hard for me to explain what “went wrong” after the second surgery. Neurologists understand completely when I describe how I feel. Neuro-hospitalist Dr. A was the one who taught me a whole bunch of $5 words to explain my minor impairments. The hard part is explaining to the layperson about my altered brain.

In The Man Who Mistook His Wife for a Hat, Dr. Oliver Sacks provides a clear explanation of a ‘sixth sense’. It is this sense that was damaged during my second brain surgery.

We have five senses in which we glory and which recognize and celebrate, senses that constitute the sensible world for us. But there are other senses–secret senses, sixth senses, if you will–equally vital, but unrecognized and unlauded. These senses, unconscious, automatic, had to be discovered. Historically, indeed, their discovery came late: what the Victorians vaguely called ‘muscle sense’–the awareness of the relative position of trunk and limbs, derived from receptors in the joints and tendons–was only really defined (and named ‘proprioception‘) in the 1890s. And the complex mechanisms and controls by which our bodies are properly aligned and balanced in space–these have only been defined in our own century, and still hold many mysteries. Perhaps it will only be in this space age, with the paradoxical license and hazards of gravity-free life, that we will truly appreciate our inner ears, our vestibules and all the other obscure receptors and reflexes that govern our body orientation. For normal man, in normal situations, they simply do not exist.

We all have this hidden ‘sixth sense’ of body awareness, but we don’t know it even exists because it is always with us. We have no way to experience a lack of proprioception without damage to the brain and/or nerve receptors.
Dr. Sacks also writes of a woman he called The Disembodied Lady–a woman who lost all sense of proprioception.

… society lacks words, and sympathy, for such states. The blind, at least, are treated with solicitude–we can imagine their state, and we treat them accordingly. But when Christina, painfully, clumsily, mounts a bus, she receives nothing but uncomprehending and angry snarls: ‘What’s wrong with you, lady? Are you blind–or blind-drunk?’ What can she answer–’I have no proprioception‘? The lack of social support and sympathy is an additional trial: disabled, but with the nature of her disability not clear–she is not, after all, manifestly blind or paralysed, manifestly anything–she tends to be treated as a phoney or a fool. This is what happens to those with disorders of the hidden senses…

While I am by no means disabled (in the sense that Christina is disabled), I do have an impairment (damage to the parietal lobe and sensory strip) that impacts my sense of proprioception. And since I was not born with this impairment, and the left side of my body is completely normal, I feel the full effect of what it is like now to be lacking in proprioception to some degree on the right side of my body.
I am fortunate that this impairment is minor.

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  • J Dubbs

    Wow, nice excerpts! I might have to pick up some of his stuff (I already have Stroke of Insight).

    I'm completely with you. Waffles (my grade II oligo) is in my right parietal lobe, so I too have a deficiency in proprioception. Right after surgery, it was the worst and I felt like a person out of my body. My neuro therapists knew my symptoms down to the wire, but still asked me to describe them. One of them was so fascinated that she kind of wished she could feel what I was feeling to understand it better. So just know this: we're all the more cooler since we understand what proprioception is.


    Since my tumor is in the cerebral cortex, it’s one of those inoperable tumors that you mentioned. I feel the effects in my speech. I find myself searching for words in every conversation I have. The great thing about typing is that I get to proofread. :)

  • Gaya

    I know you wrote this 3 years ago, but, as a medical student, it is weird to hear ” but we don’t know it even exists” and “sixth sense” in the 21st century. Why? Because kids are STILL being taught that there are only 5 senses when this has been seen as a ridiculous classification for at least 100 years.

    As wikipedia states ( “there is no firm agreement as to the number of senses because of differing definitions of what constitutes a sense.” Human senses can be classified in anywhere from 9 to 21 categories including proprioception, balance/acceleration, pressure & heat & pain (not “touch” which is a ridiculous category). (Also, don’t just trust wikipedia, everyone can read medical articles on this topic as well)

    I don’t know, but I just think it would be great to actually teach kids about the true senses that we as human possess, so if you do have brain surgery, cancer, even a genetic disorder, people can actually have the vocabulary to discuss its effects and relate to other people!! Wouldn’t it be a cool exercise in elementary school to try and classify the senses you have, discuss the difference between heat/pain/pressure, etc.? Also, proprioception for many people (me) degrades very quickly as they consume alcohol. It’s a strange feeling, and I’m always thankful for this sense they subsequent day.

    • Liz

      Great analysis!

  • lu

    does the lack of proprioception affect your social skills?

    • Liz

      Nope! It is purely physical.