In response to Xinhui's question

I hope this answers your question cause I was quite confused when I read the question.


















Firstly, there are two major structural differences between the neuroanatomy of males and females. The first of which is is the hypothalamus. Males and females differ in the preoptic area and the Suprachiasmatic Nucleus of it; the former controlling mating cycles and the latter controlling circadian rhythms and reproductive cycles. (Will not be elaborating on this in the post). When you referred to the brain stem linking the left and right hemispheres of the brain being thicker in females, I assume you are referring to the corpus callosum? That is the only bridge which connects both the left and right hemispheres of the brain. The corpus callosum is an independent structure, not a part of the brainstem (which only includes the medulla oblongata, pons, midbrain, thalamus and hypothalamus)

There have been conflicting studies on the differences between the gender dimorphism of the corpus callosum. However, researchers have agreed upon some of these differences. In the sagittal plane, the rostrum of the corpus callosum of the males is slightly larger than that of the females, while the rostral body, the isthmus and the splenium were somewhat larger in the females. In the coronal plane, the area of the male corpus callosum tended to be larger than that of the female.






















However, the statistical differences in all males and females do not differ significantly to warrant a theoretical structual difference in the corpus callosum. Females however, do have a slightly thicker corpus callosum.

A thicker corpus callosum would mean that is more white matter (consisting of nerve fibres and axon projections). This would allow for a greater amount of coordination between activities that happen in both hemispheres of the brain. Because of the thinner corpus callosum, it is harder for both sides of the brain to work together in males and on the converse, it explains the ability for females to multitask.

If you do want more information, please do not hesitate to tell me. Or you could search for it using the keywords: Corpus Callosum, Dimorphism.

Useful references:

Dubb A, Gur R, Avants B, Gee J. "Characterization of sexual dimorphism in the human corpus callosum."

Brain Degeneration

This post is specially for all the Ventures who went for the Malaysian Expedition and had one form of brain degeneration or other. Let me introduce to you to a Protista. Pronounce with me: Toxoplasma gondii.

Statistics show that half the world's population is infected with T. gondii. The protista originates from the guts of cats and is excreted in its urine. Just a breeze of wind is enough to transport hundreds of T. gondii into the respiratory and GI tract of the unsuspecting homosapien. And it is from there when the Brain Degeneration begins.

T. gondii, unlike most protista, is specific. It targets only one organelle.
















It targets the Astrocytes. (Really cool name if you think about it). Astrocytes are extremely important in the brain. Without the Astrocytes, the neurons will die. This is because of the important functions an astrocyte carries out. Astrocytes structure the brain, provide neurons with metabolic support, supplying the neurons with glucose. Astrocytes also have more complicated functions, which I will not explain in this entry. (An interesting function is vasomodulation and its role in the blood-brain barrier).

So without an astrocyte, the neurons will have a lack of nutrients and be destroyed. After that, everything is simple. Neurons die, deteriorating brain functions... Bingo. Brain degeneration.

But do not worry. It can be cured by Haloperidol, an antipsychotic.

Pictures taken from:
www-ermm.cbcu.cam.ac.uk/01002216h.htm
www.physoc.org/publications/.../article.asp?ARTICLE_ID=95

The Venture Rash

This is called The Venture Rash.

Almost half the Ventures came down with this rash during the expedition and were unable to complete it due to the pain and itchiness. Though the etiology was unknown, they went for an antihistamine jab... although I felt that it was quite a rash decision.

Interesting

Last year I mentioned about Pyrexia being a positive feedback symptom and cyclooxygenase being inhibited with the use of Paracetamol.

What really intrigues me is my current condition. I'm having a fever of about 38.6 degrees Celsius. An in-ear thermometer was used to measure my temperature. I was feeling bored (troubling neurological disease) and thus I inserted the thermometer into my other ear and took my temperature again.

Left ear: 38.6 degrees Celsius
Right ear: 37.9 degrees Celsius

I did this a few times and the results were the same! Interesting huh?
Does anyone know why?

Sensitive Women

Biologically speaking, I emphasize Biologically (in case some people do want to kill me because of my statement), women are more sensitive as compared to the other gender of homosapiens.

The average woman has 34 nerve endings per one centimetre square of facial skin, while the average man has only 17; half of what a woman actually has. Thus, women feel more pain when subjected to "painful" stimuli.

Thinking about it the other way... I just labelled men as insensitive.
Which is also biologically true.

Picture taken from: http://pixelhead.typepad.com/weblog/images/nerveendings.jpg

Clubbing

No! Not those with party and drinks, but rather that which is on your fingers.
Your fingers club too, if you didn't know.

A picture of digital clubbing, taken from http://www.mja.com.au/public/issues/181_05_060904/col10367_fm-1.jpg.

If you see anyone you know who has hands like those, or even hands which mildly looks like the one displayed, you should ask the person to see a doctor immediately. This is because the symptom of clubbing is almost universally, very bad.

Most lung diseases, heart diseases, liver diseases and even hyperthyroidism have clubbing as its symptoms.

Although the etiology of clubbing as a symptom of these diseases is unknown, scientists hypothesized that because these diseases cause the blood vessels in the fingers to vasodilate, nailbed tissues undergo hypertrophy and thus causes clubbing.

Please don't die?!

When your brain thinks that your body is dying, it sends out a signal to your muscles telling it to contract suddenly in an effort to wake your body up.

This is called a myoclonic jerk.

It normally happens when your heart rate and breathing slows down quicker than normal. Thus, the brain inteprets it as signal that the body is dying and the myoclonic jerk causes your body to have a "defibrillated" effect. Myoclonic jerks can happen in any part of the body. Most oftenly, the hands and feet.

Myoclonic jerks may also originate from lesions in the cortex and the spinal cord.

So, if you get a myoclonic jerk, 3 things. You might want to thank your lucky stars that your body prevented you from dying. Secondly, you might want to question your brain's intelligence if you knew that you were not dying. Thirdly, you might have to worry because you may have a brain problem.

Meiosis

Dear people, before I answer your questions, I think I have to clear a topic which I am super confused. Not confused by how it occurs, but rather by the technicalities and quantity.

The topic is Meiosis.

In response to John

Hey, why is it then that I get high, or feel less lethargic after eating sugar-rich apples? Why do I feel more energetic only if my coffee has loads of sugar, but still feel sleepy when I drink it black?

Doesn't taking sugar before a race enhance performance? Carbo-loading and all that? If people feel high when they are energetic, and sugar gives energy, doesnt that mean sugar makes people high?

-jloh

To John:

Disclaimer:
Though I am confident of the facts that are listed in this blog entry, I am uncertain if this is the real cause of what you are experiencing. I am only going to hypothesize and not try to give a definitive answer to each of your questions.

Definitions:
High - A sudden change in mood, delirious or hyperactive arousal of some sort.
More energetic - An increase in alertness and capability of mental activity.

1) Apples and lethargy
It is a fact that apples help to increase mental alertness. Chemicals found in the apple regulate and prevent the buildup of serotonin, another neurotransmitter. Serotonin is a “sleep-inducing” chemical which causes drowsiness. This would be the most probable cause of feeling less lethargic after eating apples. Another hypothesis would also be that apples contain a huge amount of zinc. Zinc is an integral part in many enzymes, one of which is carbonic anhydrase, present in high concentrations in red-blood cells. It is responsible for the rapid combination of carbon dioxide and water in the blood as well as the release of carbon dioxide from the blood into the alveoli to be exhaled. As such, a faster decrease in the amount of carbon dioxide would result in a faster increase of the amount of oxygen in the blood, thus causing mental alertness. Apples do not cause a fast increase in blood sugar levels, but however regulates the blood sugar levels through slow digestion and through chemicals like isoleucine, leucine.

2) Coffee with Sugar
As a coffee drinker myself, I believe that coffee with sugar does also give me that extra perk. However, I feel that coffee with a lot of sugar would not cause someone to get high but rather to be more energetic. Sucrose, table sugar, is easily hydrolysed in the stomach and is easily assimilated. As such, the brain has an excess of energy to perform its routine functions. However though the brain has an excess of energy, hyperactivity nor arousal does not happen because dopamine is not excessively released and production of serotonin is not reduced. ATP can be formed readily and thus the brain works fast, causing mental alertness. But in no way does the brain register a sharp increase in released neurotransmitters nor other excitement related symptoms.

3) Carbo-loading and Energy
Yes it is no doubt that taking sugar in the form of sucrose before races does enhance performance. More glucose is available for aerobic and anaerobic respiration to be converted into energy. After consuming the supplements, an athele does not feel high. However the "high" is not caused by the intake of excess sugar, but instead is caused by the exercise itself. During an exercise or a race, many hormones are produced. It is the endorphines, adrenaline, enkephalins and catecholamines produced. These hormones cause the high and the excitement after an exercise.

_________________________

In conclusion:
Your bodily enzymes can be more efficient in energy production after you drink a cup of sugar loaded coffee because more glucose is available. However, after you exercise, you feel "high" because of hormones produced. Think about it. The feeling that you get after exercise greatly differs from the feeling you get after drinking sugar loaded coffee. Think deeper. Your adrenal glands do not pump out adrenaline when you drink coffee with lots of sugar. Endorphines are not produced when you suck a sweet.

Interestingly, though its 1 am in the morning, I have come up with what I will call Chow's hypothesis. A neurological "high" is caused and defined by an increase in hormonal production causing a change in neurological behaviour. An increase in energy levels / decrease in lethargy is caused and defined by an increase in enzymatic function, liberating energy from glucose thus causing a change in mental alertness. =)

Hope this answers your question.

Aphrodisiac

It has to be Kink who asks about Aphrodisiacs. Nothing wrong with that, just a little amusing.

Before I introduce you to the accomplice of Aphrodisiacs, let me introduce you to a fascinating component of the human brain, called the brain stem. I will not go into details of what the brain stem actually is; or not in this entry at least. At the core of the brain stem, between the myelencephalon and the metencephalon (known unofficially as the medulla oblongata and midbrain respectively), lies the reticular activating system, which is the centre for arousal in animals. So, aphrodisiacs must be able to stimulate the system. How does it do so?


Dopamine.

As said in Biology, Concepts and Connections, Dopamine is a Neurotransmitter. What it does not say is that Dopamine, more often than not, is responsible for the after effects of aphrodisiacs. What happens when aphrodisiacs are consumed is that there is an increase of secretion / release of Dopamine from the Schwann knobs. This causes an increase in activity in that particular part of the brain, in this case the reticular activating system. This also stimulates the hypothalamus which in turn causes the "pleasure feeling" to be turned on in the hypothalamus. (As to how this happens, you can leave a question asking me to explain it to you).

Also, Dopamine is also a pre-cursor to to epinephrine (adrenaline). An increase in the secretion of Dopamine would lead to more adrenaline produced and thus, tachycardia, hypertension and symptoms associated with excitement gets manifested.

To sum everything up, Aphrodisiacs --> Increase in Dopamine production --> Stimulation of the Hypothalamus (Pleasure centre), Reticular activating system / Increase in adrenaline production.

Aren't we getting all excited?

John, will answer your really interesting question soon.

Wang, wanna contribute to the sports medicine section if I start one?

Pohboi, will do something on caffeine for my next post.

Sugar HIGH

Simply put it, there is no phenomenon called a sugar high. Sugar, as proven by Neurologists does not cause any increase in activity in the frontal lobes nor basal ganglia or any part of the brain for that matter.

Experiments conducted by scientists proved that there is no such thing as a sugar high, but rather, people now do get high because of the Placebo effect or perception of sugar as a cause of hyperactivity.
(For those who do not know, the Placebo effect is one thing that medical scientists always write down in their errors in clinical trials)

But then again, when people eat chocolates, they do get high. Sugar High? No. Endorphins rather.