The Teen Brain

Can I just tell you how much I love teenagers?  I am student teaching at a high school and I thoroughly enjoy being around these young people, with their varied personalities, interests, challenges, goals, etc..  I obviously adore science, but these kids make my job so great I'd probably still like it even if I didn't get to teach about my favorite thing ever. I just wish they all knew how awesome they are and can be.

Adolescence is a really interesting conundrum in the development of a human being.  It's an exciting time that leads up to so many big life changes- getting through school, choosing a career, starting a family, making a place for oneself in the world.  So many physical changes are happening, not the least of which are the changes in the brain.  These changes make it both easier and more difficult for people to become responsible adults, which is one reason it is so incredibly fascinating, and makes me truly appreciate and empathize with teenagers that much more.

An explosion of brain development
It is well-known that humans go through an explosion of brain development during the first 3 years of life.  Infants and toddlers are actively exploring their worlds and making many connections in their brains.  But did you know this explosion also happens in adolescence?  And interestingly, an important part of this development is cutting away parts that are no longer needed.  This process is called "synaptic pruning".

Synaptic Pruning
This term refers to the "synapses" which are the connections between brain cells.  Cutting those away may seem counter-intuitive, but it is actually a wonderful part of developing a faster, more efficient brain.  It's a very exciting time for learning.
Here are some photographs taken through a microscope of brain cells at various ages.  Notice how there is an explosion of growth as the baby develops, and then as they become school-aged, things are pruned away while what's left becomes strengthened.

I have put in a couple of great video clips to explain this process.

Short, student-friendly explanation:



More detailed (fascinating!) info on synaptic pruning - TED talk by Sarah-Jayne Blakemore:




Prefrontal Cortex Development
If you watched that second video above, you heard a lot about how the adolescent prefrontal cortex is developing.  This area of the brain is very important for higher-order or "executive" functioning skills.  That includes things like planning, predicting consequences, impulse control, and personality.

So the interesting thing is.... this area of the brain is not fully developed in humans until around age 25!  Does the sometimes irrational behavior of teenagers make more sense given that information?  Teens are very prone to risk-taking, which makes sense given the fact that they are still learning how to control impulses, predict consequences, and make good decisions.  This lower impulse control can also be an amazingly good thing!  So many people have made amazing discoveries, inventions, etc. while in this stage of brain development, because they had all the drive to go for their goal, without their brains putting the brakes on.  So while impulse control is super important, sometimes it can be overdone and stifle creativity.  Without that fully in place, teens can do some amazing things - amazingly stupid or amazingly creative and exceptional!


Societal influences
So the conundrum I mentioned is that a teenager has this amazing brain with abilities and creativity, but heightened propensity toward risk taking and foolishness and less ability to control those impulses.  And yet this is a time period when people are expected to make really important decisions that will shape the rest of their lives.

It is also a time when many young people are filling those moldable brains of theirs with garbage!  Not just garbage that will prove pretty useless in the future, like Angry Birds and Candy Crush.  But garbage that is going to forever stunt their progress and could even ruin their lives. Alcohol, pornography, and drugs can wreak havoc on a developing brain and the person whose head it's in.  But those are the things that are exciting and new, and the teen hasn't yet developed full ability to put the brakes on.

That, however is NOT an excuse.  It is important for teenagers to realize the limitations of being a teenager and rely on advice of parents, guardians, teachers, and other trusted adults to help keep them safe.  It makes perfect sense that we strive to educate young people about staying away from risky things like drugs before they even get to be teenagers.  If a young person can decide while they are a child that they will say no to drugs, no questions asked...that choice has already been made and they won't have to grapple as hard with it later on.  They will also be helped by the added protection of choosing good friends who have also made similar choices for themselves.

So to wrap this up.... teenagers are awesome creatures.  They have a LOT of brain work to do, while working with a less developed instrument than those of adults.  They need good adults who will support and guide them.  Do what you can to help educate them, but above all, love them and cut them a little slack.

Memory & Amnesia

(This post has resources and information for learning about Memory and Amnesia, for Physiological Psychology.)

Radio Lab:



6:30 Rat tests, 8:08 Chemical prevent memory in rats;  Clive Waring 42:30



 The Hippocampus and Patient H.M.(by Ted Ed)



H.M. - Nova special


 9:22 What like for H.M.  10:40-11:52 Muscle memory star test


Morris Water Maze

Directional Terms - human

Here is a handy reference on directional terms used for human anatomy.  I was nice enough to choose the pictures of people with clothes on.  You're welcome.

Here are some specific to the brain, because for humans our brain as we are standing is tilted compared to the way we hold up our heads, like so:

Source on Studyblue

So simply using superior/inferior and anterior/posterior doesn't quite work for how we normally think of orienting the brain, which is why we use dorsal/ventral and rostral/caudal.

Here is a memory aid for this.  I had a hard time keeping dorsal/ventral straight, so this is what helped me.

When I think of dorsal, a shark comes to mind with its iconic dorsal fin on its back or in this case top:

For ventral being the bottom or down, I had to think about stingrays.  They take water in on the top of their bodies and then shoot the water out the bottom over their gills.  So they vent the water out the bottom side of their body.  Hope that helps.

Left image: top/ dorsal side of stingray.  Right image: bottom / ventral side of stingray

There ya go, have fun in anatomy or whatever class brought you to find this blog!

Stay curious.

Blood Brain Barrier

No one would argue blood is very important to our bodies!  It carries very important things to all parts of the body we need such as glucose and oxygen.  It also takes out the trash by removing wastes like lactic acid and carbon dioxide.

Blood is the highway by which our immune system cells gets around our body to take care of anything that invades.  Blood is also how medications, drugs, poison and toxins, hormones, etc. can get around our bodies.

But let's talk about blood and the brain.  Our brain is a very special organ that deserves special protection.  It's the only part of our body that is protected by a 7 mm thick covering of bone, in addition to cerebrospinal fluid cushioning and protective layers of meninges.  That protects from the outside in, but we also have protection from the inside out, called the blood-brain barrier (I will abbreviate it BBB).

Blood supply is very important to the brain so it has a constant supply of energy and waste removal.  Here are some diagrams showing the blood vessels supplying the brain.

Notice the arch at the bottom of this diagram is the aorta which comes right off the heart itself

The Common carotid artery is the one you are feeling when you take your pulse on your neck

This "Circle of Willis" shows the blood supply on the inferior/ ventral side of the brain.  You can see in the image on the right where this is in relation to the brain.

Alright, so we need that blood and it definitely is there.  But how to protect it?  Some may think the "Blood-brain Barrier" is some kind of a gate the blood goes through when it enters the vicinity of the brain, but that isn't the case.  There isn't a particular spot for the BBB, but rather, it exists as protection on the capillaries (smallest blood vessels where material exchanges happen) themselves in EVERY location within the area of the brain.  It's not a matter of filtering all the blood as it travels through your head, but it's a matter of being more selective about what things cross over FROM that blood into the brain tissue.

We have special gate-keepers to protect things from getting into our brains.  Here's a cross-section of what a blood vessel in the brain looks like compared to a regular one elsewhere in the body:

Not only are the capillary cells (red in the diagram) closed more tightly so things can't leak through, but the entire blood vessel is covered with the "feet" of astrocytes.  (My favorite glia!  Here's a post about them.)

Here's a more 3D view:

See how is it a gatekeeper?  Anything in the blood must go through the astrocyte in order to get to the neuron.  Astrocytes are like the bouncer, protective big brother, or best friend: "if you want to get to the neuron, you have to [quite literally] go through me first!"

Astrocytes are really integral to the chemical integrity in the brain and are a bit of the "unsung heroes" of the brain.  Not only are they gatekeepers, but they act as a kind of mop-up crew and storage unit for any leftovers the neurons leave around (like ions, some neurotransmitters), and they serve to make sure the neuron stays well-fueled, like a mother who keeps snacks in her purse for her toddler.  No wonder astrocytes far outnumber neurons in the brain.

How do these tight blood vessels and "feet" of the astrocytes actually protect it? They are cells, which means they are surrounded by membrane- a phospholipid bilayer, which looks like this up close:

Because of this configuration, stuff that is polar (charged) or water-soluble can't get through the membrane- it can't get past all those hydrophobic fatty tails. 

YOU SHALL NOT PASS!!!
Water-soluble stuff such as nutrients (Amino Acids, Glucose, vitamins)
Polar stuff
Chemicals & toxins
Viruses
Bacteria

Stopping viruses and bacteria for the win.  Stopping nutrients? FAIL.

So to fix that, we have special transporters to let the good stuff in.  They can be super specific, so a glucose transporter will ONLY let glucose in.

Okay, you can go in...
Non-polar/ uncharged/ fat soluble stuff: this includes oxygen going in and carbon dioxide going out
Drugs that are fat-soluble
Other important stuff with special transporters embedded into the membrane to let them in, like water, glucose, amino acids, vitamins, etc. (Glucose has a wicked-awesome backstage pass, AND it knows the lead singer of the band.)


Whew!  That's a big job and an important one for the BBB.

Stay curious!

Brain Development

It astounds me how much brain development takes place in a fetus before a woman even usually knows she is pregnant.  This is an important reason why many foods are fortified with folic acid.  Folic acid (or folate) is essential in early brain development to the point that in its absence, there can be severe defects (such as spina bifida), but by the time the woman discovers she is pregnant, damage is already done, because it affects the neural tube which has already developed by day 21 of pregnancy!

Quote from the Mayo Clinic:
"Spina bifida is part of a group of birth defects called neural tube defects. The neural tube is the embryonic structure that eventually develops into the baby's brain and spinal cord and the tissues that enclose them.
"Normally, the neural tube forms early in the pregnancy and closes by the 28th day after conception. In babies with spina bifida, a portion of the neural tube fails to develop or close properly, causing defects in the spinal cord and in the bones of the backbone."

The Spina Bifida example serves to show how quickly brain development takes off.  This video has an excellent animation of brain development in a human fetus.




A couple other visualizations of the neural plate becoming the neural groove and then neural tube:

Lastly, here's a nice TED talk to get you thinking about infants in a different light. thanks for sharing Claudia Lieberwirth.

Neuron Communication

I have blogged quite a bit about Action Potentials which are the way in which a nervous impulse travels down an individual cell. (For your reference: Action Potentials and Action Potentials Up Close).


Here I will summarize what it takes for a message to be passed from one neuron to another.  If you are interested in information about the specific channels that make neuron communication possible, see this post on Neurons.

When an action potential - the electrical signals that neurons use to send messages - reaches the end of an axon, the electrical message must become a chemical message in order to cross the synapse. Neurons are connected to each other by a synapse which consists of the axon of the presynaptic neuron (the one sending the message), and the dendrite or cell body of the postsynaptic neuron (the one receiving the message), and the space between them called the synaptic cleft. Chemicals have to be sent across this space for the message to continue on. The chemicals used are neurotransmitters.

Here's a simple diagram of a synapse:

For a little more information and overview of neuron communication, here is a more detailed diagram:

When the electrical signal reaches the end of the axon, a special thing happens with Calcium entering the cell which allows those vesicles full of Neurotransmitter chemicals to exocytose.  That's a fancy word meaning the vesicle smooshes into the cell membrane, kicking its contents outside the cell- into the synapse.  Those neurotransmitters are then free to act on the postsynaptic cell dendrites or body to continue the message along!

But how did those vesicles of neurotransmitter actually GET there?  The cell factories that make neurotransmitters which are mostly made of protein, are waaaaaay back at the cell body, but it has to be released at the terminal button of the axon!  Axons can be very long, like so:

Neurotransmitter vesicles are continually made by the neuron (each neuron only makes one particular type of neurotransmitter), and sent down the axon.  They get there the same way you would travel a long distance- on a "highway" of sorts.

Here is a great animation of the whole neuron communication process, and you will see vesicles coming down to the end of the axon.




So, the cool thing is those vesicles are literally "walked" down the microtubule highway.  In my favorite video, you can see this happen:




Lastly, I found this funny little video about the life of a motor protein (the alien-looking guy that walked the vesicle down the microtubule).  Enjoy!





P.S.  While searching for images, I ran across this amazing blog, so here is a great reference on the brain and neuroscience, explained in simple terms in much the same way I try to do my own blog. The Brain Geek

Stay curious!
-Julie

Sleep

I am a big fan of sleep. Whenever my brain needs a good reset, 9 hours of snoozing always does the trick.  This is pretty much me:

You know that marital advice that says "never go to bed angry"? Well everyone should consider ignoring that. When I get upset, the best thing for me is to sleep on it so I can think more clearly in the morning. Staying up late to try to resolve a disagreement before bed is just plain stupid, cause your power to be objective, calm, reasonable, creative (higher-order thinking skills required to solve a problem), decreases exponentially the more tired you are. Probably that advice is supposed to mean something like - delay solving the problem for now but assure your partner that you are still devoted to them by reaching out with kindness before bed. One of the best kindnesses: "I'll give you a break from discussing this problem so you can take care of your brain and I can take care of mine, and we'll revisit the issue later on with our frontal lobes in good functioning order. For now, I love you. Goodnight."

Radio Lab has done a number of awesome podcasts on sleep, sleep deprivation, and dreams:   Radiolab Sleep Podcasts

Here's the first one "Sleep":

Theodore Schwann

Theodore Schwann (many sources also spelled his name Theodor) was a man who lived in the 1800's and is remembered as a great scientist.  His actual scientific career only lasted five years!  And yet, in that short time (1834-1839), he made many very important discoveries in Biology and Physiology.

Source

Cell Theory
Shortly after German Botanist Matthias Schleiden discovered that plants are made of cells, Schwann discovered that animals are as well (Source).

Alcoholic fermentation
He hypothesized that fermentation wasn't a reaction with nitrogen in the air as people then believed, but that tiny organisms (yeast) were eating the sugars of the fruit and then excreting carbon dioxide and ethanol.  People in his day noticed yeast multiplied with fermentation, but he was the first to suggest they were the thing doing the fermenting, rather than just a byproduct of it.  He also stated that yeast were living plant-like organisms, firmly establishing fermentation as a biological process.  He was publicly ridiculed for this hypothesis which came at the end of his short career and probably helped lead to its demise, as he could no longer get funds or promotions to continue doing scientific research.  (Paraphrased from The Other Brain, by R. Douglas Fields, 2009, and Wikipedia- Theodore Schwann.) 

Digestion
He suspected that hydrochloric acid wasn't the whole story with digestion.  He discovered Pepsin, the enzyme that helps break down proteins (The Other Brain). He also showed that bile is essential to digestion, and coined the term "metabolism" describing chemical changes in animal tissue (Source).

Schwann cells
The myelinating cells in the Peripheral Nervous System are his namesake, since he first described them.  He studied nerves, noticing they had little dew-drop like structures running the length of them.  He thought that a neuron being built during development must join with other cells to create the long axon by fusion, and the Schwann cells were remnants of this process from those fetal cells.  Although his speculation was incorrect, these cells still carry his name.

Source

There's a brief summary of a great scientist's work.  I read about him in the book I've currently got my nose in (and hoping to finish before school starts back up), The Other Brain, by R. Douglas Fields.  It's all about Neuroglia, aka glia, glial cells.  To read an overview of all the types of Glia, go to this post: http://biogeonerd.blogspot.com/2013/08/neuroglia.html

Neuron Ion Channels - Detailed

Inward rectifying potassium channels.  This is what started all this.  Just a little paranthetical aside in my Neuroscience teacher's notes that left me curious.  One thing led to another, and here we are.  Ion channels.  Hope you learn something like I did.  Enjoy!

A plethora of potassium channels
Here is a short video showing the molecular structure of a Potassium channel and how it can be perfectly selective to allow Potassium and not Sodium through.

And look at this beautiful top view of a potassium channel with a little purple potassium ion in the center.

Inward-Rectifying Potassium Channels
What does inward-rectifying mean?  Simply put, it just means that voltage travels inward more easily than outward.  So this name tells us that Potassium will move into a cell when open.
(Example - cardiac muscle cells- responsible for the long refractory period between beats, to avoid tetany; kidneys, regulating potassium ions

Action Potentials: Delayed Rectifier Potassium Channels & A Type Channels (outwardly rectifying)



Tandem Pore Domain Potassium Channels (Leak Channels)

Voltage Gated Potassium Channels




********This post under construction!  I just found a textbook with an entire chapter on ion channels, so after I study for my test I will dive into this and finish the post...  thank you for not hating me too much for leaving you hanging.  You'll just have to subscribe to learn more! :)

Neuroglia

Neuroglia are support cells for the neurons in the nervous system.  They have a very wide variety of functions, and I'm sure it hasn't all been discovered.

Now, here's the interesting thing.  Studies done on (supposedly) Einstein's brain, show that he didn't really have any greater number of neurons, but actually had more neuroglia, particularly astrocytes, which were concentrated in the area of the brain involved in imagery and complex thinking (NPR news article on the subject, June 2010).

Picture source

My thought is that we don't know which came first - the astrocytes or his genius.  Perhaps using your brain well leads to making more astrocytes in order to support how much you're using certain areas of the brain, rather than the astrocytes coming first and giving natural intellectual ability.

So, on that note, we'll take a look at these cells. :)  Here is a good way to categorize them, from interactive-biology.com.  I'll expound on these more.

Source (interactive-biology.com)

 And for the visual folks out there, here are a couple of diagrams.

Source

Source

Neuroglia in the Central Nervous System 

Source

Oligodendrocytes (a type of macroglia)

• Support neurons in the CNS by myelinating.  Have multiple "arms" with which they myelinate several axons.
• Myelination insulates axons of neurons which allows their conduction to go much more quickly.  (For some info on how this works, go to this post on action potentials and scroll to the bottom for "saltatory conduction".)
• Similar function in PNS is performed by Schwann cells

Astrocytes (a type of macroglia)

• Named for their star appearance (astro = star, cyte=cell)
• Maintain neuronal environment
• Part of the blood-brain barrier
• Control what substances are transported from blood to neural tissue (Source article)
• Have their own signalling system and can regulate messages of neurons
• Topic of much research - some are calling these "the other brain" (Source article)

  

  Source

  
  

My note on Astrocytes: wow, these look like such an exciting topic right now!  These are the cells that Einstein's brain had more of, and it looks like we are just discovering how integral they really are to the function of neurons!

Microglia

• Immune cells of the CNS - these bad boys take care of infection by foreign pathogens, and keep any abnormal neurons in check, gobbling up anything that shouldn't be there.  In short, they are the macrophages of the brain and spinal cord.
• Named for being small (micro), which allows them to get around to whatever small spaces necessary for fighting infection.

Source

Ependymal glia

Source on brainyinfo.com

• Ciliated epithelial tissue
• Line the ventricles and choroid plexus of the brain
• Make Cerebrospinal fluid (CSF)
• (Very good source article on brainyinfo)

Neuroglia of the Peripheral Nervous System
Schwann Cells/ Neurolemmocytes

Source

• Schwann cells have the same function in the PNS that Oligodendrocytes have in the CNS, namely myelination.
• The cell wraps itself around the axon of a neuron, insulating it, as seen below.  Pretty cool, eh?

Source on brainyinfo.com

Satellite Cells

• Cushion neurons
• Help control the environment of neurons and maintain synaptic integrity by insulating areas where there shouldn't be additional synapses on the neuron.

Brain Food - Nutrition for Learning & Memory

What are the best foods for learning?  Can your diet help improve your memory?

These are foods you should add to your regular diet which will boost your brain's ability to function and help you do well in school.  For info on what to eat for alertness before/ during studying, I will make another post and put the link here when it's done.

"Top Ten" Brain Foods
(according to this article)

1. Fish - Omega3 Fatty Acids are crucial to neural health, and can even prevent dementia.  They also promote heart health by reducing risk of blood clots, which will reduce risk of heart attack. Bonus!  It's recommended to have at least 2 servings of fish per week.

2. Nuts - high in essential fatty acids which help your brain perform its best, as well as iron which will help in getting oxygen to the brain (because the major component of hemoglobin in your RBCs is iron).  It's also got unsaturated (good) fats which will give sustained energy.




I would also add Avocados to this category, because they have a great amount of unsaturated fats which will give the same benefits as the nuts.  As a bonus, they have no cholesterol or salt!  Here's a site with info on avacados, how to pick a good one, how to slice, etc.: http://sprouts.com/food-tips/avocados-thinking-outside-the-guacs



3. Whole grains (quoted directly) - Eating lots of refined carbs like white bread and pasta is not only bad for your physical health, but it also leads to sleepiness, lethargy, and mental dullness. Luckily, whole grains tend to have the opposite effect and can lead to enhanced memory function and even better grades. Chow down on whole grain breads, crackers, and pasta while you study for a quick energy boost.

This source website has some info on a few whole grains you might not know about

4. Apples - skins of apples contain an antioxidant called quercetin that enhances memory. :)  Plus it's a good source of fiber to help you feel full, and is a very quick, portable source of energy.



5. Cruciferous Vegetables (direct quote) - In case you’re a bit rusty on your vocabulary, “cruciferous” vegetables make up a family of vegetables including broccoli, cauliflower, cabbage, brussels sprouts, and bok choy. A long-term study conducted by Harvard Medical School revealed that these type vegetables had the most positive effect on memory retention, meaning they are the most likely to help you achieve better grades. Eating these vegetables raw is the best way to get the optimal nutritional benefit, since cooking them often cooks out the nutrients your body and your brain need most.


6. Dark Chocolate (direct quote) - Not just any variety will do, but a certain type of chocolate – dark chocolate – can feed the brain, not only by improving memory, but also by increasing blood flow to the brain, increasing alertness and clarity. The darker the chocolate, the more benefits your brain will receive.

Click the following link for another article with more great things about dark chocolate, such as the facts that it has antioxidants, it prevents blood sugar spikes, even helps keep your teeth healthy! (Who knew?) Article on fitday.com

7. Spinach - great source of folic acid which can reverse memory loss, lots of antioxidants, vitamins, fiber, and even some Omega-3 Fatty acids.

8. Berries (direct quote) - Here’s a quick solution for the problem of how to study better—pop a handful of colorful berries in your mouth as you prepare for your next test or exam. Colorful berries such as blueberries, cherries, black currants, raspberries, cranberries, blackberries, gooseberries, and even grapes have significant health effects directly related to brain function. Not only do these flavorful snacks reduce the level of toxins in your bloodstream, but they also contain phytonutrients and antioxidants that improve blood flow to the brain and enhance neural activity as well.

9. Legumes - very high in protein to fuel your brain without blood a sugar spike and plummet, and also have folic acid to help with memory recall.

10.Onions - The compounds in onions, namely anthocyanin and quercetin, have even been shown to prevent Alzheimer’s disease.  Help improve memory and focus.




Another case for some good proteins

Amino Acids Can Excite or Calm Your Brain
The amino acids tryptophan and tyrosine must both cross the blood-brain barrier in the same pathway. If tryptophan crosses the barrier, it will have a calming effect. If tyrosine wins out, then you will be energized and alert. A high-carbohydrate meal can increase the brain's tryptophan levels, and hence the serotonin that promotes contentment and normal sleep. Therefore, a carbohydrate-rich meal may be more appropriate for the evening meal.		On the other hand, one can be energized for hours after a morning meal high in protein, because it raises tyrosine levels in the blood and brain – causing neurons to manufacture norepinephrine and dopamine, two neurotransmitters that promote alertness and activity. Tyrosine is crucial to brain power and alertness in another way. It's also needed for your body to make active thyroid hormones. Low blood levels of tyrosine are associated with an underactive thyroid gland. (Extreme thyroid deficiency causes severe mental retardation known as cretinism.)

Source above text is from

Tyrosine is actually made from phenylalanine in the body.  It's used to make neurotransmitters including epinephrine, norepinephrine, and dopamine.  Here are some dietary sources:

Tyrosine is found in soy products, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.

(Source)

Another source has some info on Amino Acids boosting brain function, on livestrong.com.

Brain Food No-No's
Some things NOT to eat (avoid as much as possible): alcohol, caffeine, and sugar (as in simple carb sweets).  There are many ways these items are bad for your health, a couple of which are their propensity for being addictive, help you gain weight, and to produce a giant sugar crash that will put your brain out of commission.  Here is another nice physiological reason, related to the neurotransmitter Dopamine.

Dopamine
Dopamine is the neurotransmitter needed for healthy assertiveness and sexual arousal, proper immune and autonomic nervous system function. Dopamine is important for motivation and a sense of readiness to meet life's challenges. One of the most vulnerable key neurotransmitters, dopamine levels are depleted by stress or poor sleep. Alcohol, caffeine, and sugar all seem to diminish dopamine activity in the brain. It's also easily oxidized, therefore eat plenty of fruits and vegetables whose antioxidants help protect dopamine-using neurons from free radical damage. More and more healthcare professionals recommend supplementing with vitamins C and E and other antioxidants.		Age-related cognitive decline is associated with dopamine changes in the brain. People whose hands tremble from Parkinson's disease have a diminished ability to synthesize dopamine, which is crucial to fine muscle coordination. Attention deficits are also connected to dopamine.

Source above text is from
.

Stanford

.
Visualization for Alertness & Success
Another tip while you are studying and taking tests, you want to make sure your Reticular Activating System is active (as I'm sure you already know, this part of the brain is what controls your awake and alert state- it determines what you focus on).  A great way is to actually visualize yourself succeeding.  You hear a lot about thinking positively.  Well it's true.  Successful people visualize themselves being successful, and that actually makes them more successful.  Here's an article if you want to learn more: http://www.ginabellinc.com/successgps/

By the way, since the RAS includes the Thalamus which takes in sensory info - so if you use a multi-sensory approach to visualizing and studying, you can trigger your brain during the test.  For instance, if you always chew the same flavor of gum while studying Physiology and visualizing your success, then chew that same gum during the quiz/ test, it could help your RAS pay attention to being successful!  Just a thought. :)

Hey, if you remember from the post about the brain anatomy and functions, I pointed out that the Reticular Activating System is just as active while you're dreaming as when you're awake - perhaps that's the logic behind listening to lectures, music, etc. while you're sleeping or meditating too!  Interesting...