One More Reason

Yet one more reason to exercise regularly: It staves off age-related cognitive decline.

Yes, it’s a graph. I apologize. Don’t stop reading! Notice how every line goes up when you compare the ‘Activity High’ column to the ‘Activity Low’ column. The results indicate that memory, speed-of-thought, and executive function are all preserved better in people who exercise, compared with those who don’t.

If you’re curious, the ‘WML’ stands for “white-matter lesions”. The white-matter is a brain tissue that often shows lesions (= spot defects) with vascular dementia. Patients with lots of white-matter lesions were compared in a different group (the dashed lines), than the patients with fewer white-matter lesions (the solid lines). Essentially this was a means to compare “apples with apples, and oranges with oranges”. The results are the same in both groups: exercise staves off cognitive decline, regardless of your vascular status.

Book Review: Another Day in the Frontal Lobe

By Katrina Firlik.

Neurosurgeons are quirky people. I’ve yet to meet one who’s “normal”; mind you, my observation-count of this rare species is still only three, so perhaps my sample-size is just too small. In her book ‘Another Day in the Frontal Lobe’ Katrina Firlik describes the habitat, behaviours, and temperament of the neurosurgeon. Here are some of the findings (corroborated with my personal experience):

• Quirk 1: Neurosurgeons are your superior. It doesn’t matter who you are, or what you do, brain surgery tops everything. I suppose that’s the attitude that naturally comes after 11 years of speciality training in an isolated culture. Firlik notes the stereotype, confirms its accuracy, and then exemplifies it with an out-right haughty tone throughout her book.

• Quirk 2: Neurosurgeons do only a few things very well. You’d think that the neurosurgeon would be the ultimate expert on function of that mysterious organ, the brain. They’re not. In fact, neurosurgeons handle only a small subset of brain disease. This includes trauma, tumours, and seizures. Comprehensive brain/mind function is left to be studied by the psychiatrists, psychologists, and neurologists, with each one contributing a unique piece. In fact, most neurosurgeons spend most of their time operating on the spine (that’s where the most money is to be made).

• Quirk 3: Neurosurgeons are mechanics. Brain surgery is not, well, brain surgery! If there’s too much fluid in the brain causing a build-up of pressure, you drain some to restore normal pressure. If there’s a tumour compressing on brain structures, you remove it to decompress the brain. Obviously I’m vastly simplifying, but most neurosurgical work is founded upon basic mechanical principles.

• Quirk 4: Neurosurgeons are emotionally tough. This is a necessary attribute. Chances are, that once you’re willing to let someone cut into  your brain, things are looking pretty bad. The outcomes of neurosurgical patients are usually not happy stories.

You may accuse me of speciality profiling; of drawing on superficial stereotypes. I protest that, in medicine, the stereotypes are usually objectively true. Each speciality has a unique personality of doctor associated with it. And it makes sense. When you train for many years with a small, isolated, community day-in, and day-out, you tend to form an identifiable culture. When medical students choose their future directions, a large factor is often the culture with whom they get-along the best.

Neuropathology

It makes a slick, slimy, wet-but-not-dripping sound as the knife glides through. Slice one. The texture is gelatinous and moldable, but it holds its shape. White and grey; there are patterns in the slice. Like cloud-gazing, you can make-believe that the shapes are mysterious life-forms.

It used to be alive. A day ago, maybe two. More than alive. That piece of tissue, now split indelicately on a slab of marble, felt emotions. It thought up ideas, and imagined shapes in the clouds it saw. It had an identity, and a personality. Now it sits cold; a lump of withered sponge, unable to defend itself from the blade that is slicing it apart.

The blade is wielded by a pathologist, demonstrating to us the gross anatomy of normal brain tissue, and some pathological (diseased) findings. Pathologists (in addition to other things) perform autopsies to determine causes of death. Dead bodies are regularly their domain. Unlike the neurosurgeon, who explores the brain while it is warm, pulsing, and ever dancing with electrical activity, the pathologist handles tissue more like damp tofu.

Evidently, the early anatomists perceived as much awe when they pro-sected cadaver brains. The names they assigned the structures sound like discoveries from an exploratory deep-sea dive: the geniculate nucleus; the hippocampus, which in Greek means sea-horse; the cerebral aqueduct. Shapes in the clouds…

TED Talk: Oliver Sacks

Oliver Sacks is the Jane Goodall of neurology. He has spent his entire  professional career observing patients, dutifully recording in his notebooks, and publishing reports of his findings that illuminate how the mind works. Most of his published work tells personal stories of patient experiences. Most notably there is ‘The Man Who Mistook his Wife for a Hat’ (a man with visual agnosia) and ‘An Anthropologist on Mars’ (perceptions of people with autism).

In this TED Talk, Oliver Sacks explains Charles-Bonnet Syndrome –  a hallucination syndrome experienced by people who lose their vision. I was surprised to learn that up to 10% of people with vision loss experience Charles-Bonnet hallucinations, but only 1% of them report it because they are afraid of people assuming they  are going insane (which they are not).

Check it out, it’s fascinating:

Electrocutions and Mind-Reading

“This might make you feel dizzy; hold onto the arm-rests, just in case.”

With these instructions, the doctor proceeded to inject a cup of cold water steadily into my classmate’s ear . Disconcerting. Surprising. This is the field of neurological investigation.

Sure, neurologists use conventional imaging techniques like MRI and CT, but they also have an arsenal of tests up their sleeves that are more unique. Some date back more than one hundred years. Others are cutting edge. From my superficial viewpoint, however, they all have one thing common: There’s something just odd about them!

The technique I was describing is called ‘Caloric Stimulation’. Water injected into the ear canal tricks the vestibular system (your ear’s system for maintaining balance) into thinking that you are turning either to the left, or to the right, depending on the temperature of the water. The response you look for is compensatory movement of the eyeballs. Like most predators, when we move our heads, our eyes reflexively move in the opposite direction so that they remain fixed on the same target. Since the reflex relies on brainstem functioning, neurological diseases that impair the brainstem can affect this reflex. Caloric Stimulation is therefore used to assess normal or disease functioning of the brainstem.

Now if you thought Caloric Stimulation smells a little bit like a dorm-room prank, wait till you hear about Nerve Conduction Studies. The purpose of NCS is to assess the health of nerves beyond the spinal cord, for example in your arms, or in your legs. Nerves communicate with electrical energy. So, to interrogate the nerves directly, neurologists pull out their stimulators (reminiscent of cattle prods, or police tasers) and deliver electric shocks through the skin. They measure the speed of electrical impulse through the nerves, and also contraction of the muscles that the nerves enervate. Nerve disease and muscle disease can both be detected by NCS.

One surprising fact, is that there exists a wide range of sensitivity to electrical stimulation. Some people handle being electrocuted better than others. Among our small group, one classmate could easily withstand more than 100 times the amount of electrical energy than the most sensitive classmate (who swore in severe pain at even small shocks!). Both fit within the wide range of normal sensitivity.

Perhaps the oddest neurological investigation of all: Electroencephalography (EEG). Straight from the movies, this is the test where a bundle of electrodes are placed over your shaved scalp, and your brain-waves are plotted with spiky lines on graph. EEG literally reads your mind. Now if only it could read thoughts! But brain activity, even plotted neatly on a graph, is more than a little confusing to read. EEG is used to diagnose various types of seizure, and sleep disorders.

Polyradiculoneuropathy

Seriously? … Polyradiculoneuropathy? Do you really need to make it all one word? Don’t you think ten syllables is a bit much?

Seat of the Soul?

I believe in a soul. I believe there is more to “me” than a body. Neurons, blood cells, respiratory gases; physical matter – certainly I rely on these to function, but they do not control me. I am not merely physical, a puppet to the unyielding forces of physics and chemistry.

Which leads me to the interesting, and unavoidable question: where is the interface between body and soul?

Human cultures have long asked this question. The Ancient Egyptians believed that the bodily residence of the soul is in the heart. Emotions, thoughts, and choices all take place within the heart, they thought. Although we’ve since discovered that these are actually functions of the brain, even today we still carry some vague association between the physical heart and the emotions of passion.

Also in the running for seat of the soul, historically, is the pineal gland. Its heavily-protected, highly vascularized location deep within the centre of the brain has led many new-agers, and occultists to wonder about whether it has a metaphysical role.

In the US at the beginning of last century, there were physicians who would weigh bodies shortly before death, and then immediately afterwards. The idea was that the difference between the two readings could give an approximate value for the weight of a human soul. The idea strikes me as strange, since my bias is to consider the soul immaterial (and hence weightless) by definition.

With the advent of modern psychology/psychiatry/neurology, I think we’ve since narrowed down the quest for the soul’s resting place to the brain. The brain is where decisions are made, emotions are experienced, and consciousness is maintained. Of course, the brain is an awe-inspiringly big place, with a lot of complicated activity. Where exactly is does the soul have its influence? And what form does that influence take?

Let’s say I that I make a conscious decision (any decision – the content doesn’t matter). As a proponent of free will, I would suggest that my decision is not simply the net result of neurons firing in my brain. Rather, in some place, and at some point in time, my immaterial soul must initiate a material effect on the stuff of my brain to exert its willpower.

What does this event look like? Does a particular neuron fire without stimulus? Are new neurotransmitters created from nowhere to initiate a decision-cascade? You may protest that these events break the laws of electrochemistry, and the conservation of matter (the laws of nature). But that’s precisely the point. Any decision-making mechanism that is bound by the laws of nature, would be incapable of making free decisions.

Yet more unanswerable questions distracting me from what I should be doing: studying neurology. Sigh.

A Versatile Brain

The study of Neurology is haunted by a paradox: Does a human brain (like mine) have the capacity to understand the workings of … a human brain? For that is exactly the type of circular relationship that a student of neurology attempts to establish. Can thoughts fully illuminate the process of thought-generation? Can I understand the biological mechanism of understanding? Questions like these pass through my (possibly incomprehensible) brain at times when I probably should just stop procrastinating, and start studying Neuroanatomy.

Today was the first day of class. No doubt you’ve guessed by now, we are beginning Neurology. Hence the bizarre, and somewhat confused, revelations about the brain. Here’s another one:

My brain already knows Neurology. Every day, my brain sends electrical signals within itself and to the appropriate parts of my body to accomplish my daily living. It carefully sends each signal through a complex network of nerves, requiring a near-perfect “understanding” of Neuroanatomy. The problem, is that I cannot consciously access this “knowledge” that my brain puts into work on my behalf. So instead, I’ll spend the next two months studying to consciously “know” something that my brain already seems to know.

Another less-convoluted revelation from today, is that surviving medical school requires a versatile brain. This first day alone involved: setting up the technical equipment in our classroom, concentrating through four hours of Neuroanatomy lecture, a brisk trip to the rental company during lunch-break to pick up keys, getting stabbed with a vaccination needle, a group lab assignment, a Town Hall meeting with the school executives, prosection of the heart and lungs from our cadaver, and a very late dinner with friends. My head hurts! It’s going to take  me a few days to get back into the wild rhythm of life here …