Christmas Poem

For those of you that fall into the category of grumpy curmudgeon who grumbles that retail stores are already putting out Christmas paraphernalia, apologies for a Christmas-themed post in early November. Below is a poem I wrote for my in-laws. To put the poem in context, one of the first interactions I had with my now mother-in-law was her telling me that during Christmas she wasn’t having any of my skeptical, atheist nonsense. In her house everyone believed in Santa Clause or didn’t receive any presents from him; deal with it.

This poem was my response.

On the scientific validity of the magical, immortal man known as Santa Clause

 

Here is the problem I’m facing this season

I’ve devoted myself to both science and reason

But a challenge was stated that told me, in essence,

Believe in Santa or you won’t get any presents.

I could never accept such a fable I fear

A single man bringing gifts to each house once a year

Thus you see that I’m stuck in a quandary indeed

I don’t believe in Santa, but there’s shit that I need

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Dopamine: the reason you pursue reward

It was a beautiful fall afternoon. The breeze sent leaves of yellow, orange and brown sailing through the air. As my unleashed companion and I walked briskly through the park, the wind also carried something far more troubling straight into the sniffing nostrils of my faithful friend, the scent of a young female canine. I watched as my dog’s attention suddenly turned to the Collie and her master who were also enjoying the nice day at the other end of the park. By observing the subtle changes in his posture I knew where this was going. His head lifted and turned to the unaware pair, the tension spread through each muscle in his body starting with his head and ending in his hind legs which were now fully primed to spring forward. Not wanting him to disrupt the plans of innocent bystanders I responded in the only way I knew how. “Come!” I said as clearly and seriously as I could manage. His head turned toward me, and his ears perked to attention. But instead of immediately bounding over to me as was usual, I could see signs of the conflict raging in his brain. What to do? Explore that interesting-smelling female or obey the call of his friend and companion?

But wait, let me interrupt the story right there. Why would the sound of my voice have even a small chance of changing his plans to go explore this other dog? At first, the answer to this question seems obvious; because I spent years training him by giving him a bacon-flavored treat each and every time he responded appropriately. Indeed, humans have been using this trick of rewarding good behaviors to train animals – and other humans – for thousands of years. But upon closer examination my rigorous training program is a perfectly good answer to how I got my command to be so important to my little friend, but it doesn’t answer why it works so well that a single word from my lips now has the potential of overriding the instinctual urge to barrel full speed towards this possible mate. Decades of neuroscience research have finally filled in this question, and the answer it turns out is a microscopic, chemical neurotransmitter floating around in the brain called dopamine.

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Adenosine: the reason coffee works

Have you ever woken up and run straight to your coffee maker because you had something important to do that morning and you needed to be especially alert? Or have you ever poured an extra evening cup of joe because the sun was setting but your list of to-do’s was nowhere near completion? Or have you ever scotch-taped your eyes open and stared at your hand to see how bad it was shaking because you were hoping you could still drink another cup of coffee without having a heart attack because god help you, you just wanted to finish writing that dissertation? …ok, that last one might have just been me. Anyway, if you’ve ever found yourself leaning on the world’s favorite beverage to give you that extra kick, you’ve been tinkering with your brain’s adenosine system.

Adenosine

Adenosine is a very common chemical found throughout your brain. Just about every kind of neuron in your brain has receptors that adenosine can fit into and activate. Caffeine, the active and stimulating ingredient in coffee, works by blocking the adenosine in your brain from reaching those adenosine receptors. And actually adenosine is common outside of your brain too; that’s why drinking too much coffee can cause effects outside of your brain, like heart problems. But why would preventing a chemical from sliding into a receptor make you feel awake and alert?

Adenosine is a strange little neurotransmitter because taking a drug (like caffeine) that prevents it from stimulating its receptor is almost always performance enhancing. With every other neurotransmitter I can think of, blocking its actions might help in a very specific situation or disease but is going to come with lots of bad consequences. Because usually you need those little chemicals to keep doing their jobs. But if blocking adenosine is universally performance enhancing, that implies that adenosine’s role in the brain is to reduce our performance. Why in the world would we have an entire system in place in our brain that generally reduces performance?

To explain why having a performance reducing neurotransmitter is a very good thing for your brain just think of the brake system in your car. The entire purpose of the automobile is to move forward quickly, so why in the world would we develop an entire system with hundreds of moving parts with the sole purpose of slowing down and stopping the car? Ah, right. Because without brakes it would be virtually impossible to use the vehicle without it ending in a terrible accident. The same goes for your brain, it works by having hundreds of billions of neurons furiously processing information as fast as they can. But sometimes they can work too hard and without a way to put on the brakes and slow everything down there could be terrible consequences.

And that is adenosine’s job; it slows your neurons down. Specifically it makes them stop firing. Neurons work by receiving lots of information, processing that information, and then sending the new, processed information on to other neurons down the chain. We call that process of sending the new information down to other neurons “firing”. So whenever a situation arises when a group of neurons start firing too much for their own good, the brain quickly releases lots of adenosine to make it stop.

In what situation would the brain need to apply the brakes to a group of neurons? There are several examples of when this is a helpful thing. One such example comes from studies that have shown that the levels of adenosine slowly increase throughout the day. That means the longer you’re awake, the more adenosine is floating around to slow your neurons down. This makes adenosine a kind of timer; by slowly ramping up over the course of the day it can make you feel less and less alert and therefore help you feel like it’s bedtime. That’s why drinking coffee makes it hard to fall asleep; you’re pulling your brain’s foot off the brakes allowing everything to run at full speed.

Another time your brain needs to put on the brakes is to prevent seizures. Seizures are caused by a group of neurons firing too much. If one region gets over-active, it can cause other regions connected to it to start firing too much as well. This spreads like wildfire across your brain until eventually you have a full blown seizure with neurons all over your brain firing as fast as they can. There is a mechanism in the brain that causes the release of adenosine whenever neurons are firing so much that they use energy faster than they can get it supplied by the blood stream. So if you have a group of neurons going crazy, that over-firing will cause adenosine to get released and thus help slow the neurons back down.

Adenosine will also get released when energy is not getting fed to the neuron properly, like during a stroke. In that case the neuron might be firing at a normal, healthy rate but if something happens to the blood flow feeding the neuron then adenosine will get released and slow the neuron down. This is a good thing because it helps the neuron conserve the little energy it has remaining and thus keep it alive longer. Adenosine helps keep neurons from dying in the hopes that the energy supply will resume soon.

So why does coffee help you feel energetic and alert? Because coffee, that is caffeine, is a chemical that takes the foot off the brake in your brain. It prevents adenosine from binding with its receptor and thus prevents it from slowing things down. Without the adenosine brake, the neurons in your brain are free to fire without inhibition and thus you feel more energetic and alert.

At this point you might be thinking “I wouldn’t drive my car without brakes, so should I be drinking those cups of coffee every morning?” Fortunately the health research seems to suggest that drinking some every day is ok, as long as you’re not drinking too much. So feel free to caffeinate your brain, just don’t overdo it.

Politicus Cerebri

Neurotransmitters and the mind

When I was a child, I remember hearing something that turned my understanding of what it means to be human upside down. We were talking about depression, and this person said something to the effect of “well with some people it’s not just sadness or something psychological; some people just have a chemical imbalance that makes them feel depressed.” Chemical imbalance? I still remember that conversation because it struck me as strange and confusing that chemicals could influence the way you think or feel.

Now, after studying neuroscience for the past 10 years, I look back and realize that, just like Alice in Wonderland, that rabbit hole goes deeper than I could have imagined. When I was young I found it baffling that chemicals could influence how I think or how I feel; now, I know that chemicals are how I think and they are how I feel. Chemicals don’t influence your thoughts, they are your thoughts.

This can be a very uncomfortable fact for many people. There is no thought or emotion deeper than the brain. And the brain is made of roughly one hundred billion neurons squirting chemicals at each other.  The part of you reading and understanding these words, the part of you that calls itself “I”, and the part of you that falls in love is a brain. That fact is what made me fall in love with neuroscience; I can’t think of any topic more interesting than how a biological system creates the rich experience of having a human mind.

In that context, understanding how these neurons work and what those chemicals are doing is not just another mundane examination of cellular function, it is the study of how you think and feel the way you do. It is the study of what you are.

For the next few posts I want to write about just what these mysterious chemicals are and what they are doing. These tiny little molecules are responsible for making you think, feel and behave the way you do. They are the reason when you walk into the grocery store and see on display a hot plate of donuts you suddenly find one in your shopping cart even though “donuts” are nowhere to be found on your shopping list. They are the reason why drinking coffee makes you feel alert. They are the reason why rubbing your sore back actually makes the pain go away (briefly). If you find this connection between tiny chemicals floating around in your brain and the deep complex experience of being a human being fascinating then join me as we walk through different neurotransmitter systems to see what neuroscience has taught us about what they do and how they work.