This is a fantastic science-related website!

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MadSci Network represents a collective cranium of scientists providing answers to your questions. For good measure we provide a variety of oddities as well.

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Get all the details at Sci Network (http://www.madsci.org)

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A question posted by Teddy, a science graduate of UC Santa Barbara asked this question:

…Is it known how many calories human thinking takes?  I see in your archives that the brain uses 10% of the body’s energy, and I’ve heard that our brains draw 25% of our blood flow, and that 25% of the heat radiated from our bodies is radiated from our heads, but is this true for all mammals?  For all primates?  How many calories are consumed by the “higher functions” of the brain that are special to humans, and how many by the parts that are found in other mammals?

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Alex Goddard, Grad student, Neuroscience, Harvard Medical School answers…

Hi Teddy,

That’s a good question! I think the short answer is that it’s less energy than you might expect. I’ve tried to explain why I think so below.

First, I’d say that the basic energy expenditure per unit area of brain is probably the same between different types of animals. A human brain uses more total energy than a rat brain because it’s bigger and more complex. This idea probably applies to heat generation, blood flow and caloric requirement as well.

I saw somewhere that the brain uses 20% of your caloric input for the day. I don’t think that number is absolute, but it seems reasonable. So, assuming you eat 2000 calories per day, your brain uses about 400 calories per day. Then, we need to ask, how much is spent on ‘thinking’ or cognitive abilities? (I’m leaving the idea of consciousness out of this, because it has no definition that has been agreed upon)

To start out, we need to realize that the energy expenditure of the brain at rest is really quite high. This is because maintaining a neuron’s baseline is very metabolically “expensive;” before neurons can transmit information, they have to be properly connected and maintained. A neuron’s ability to use electricity to transfer information comes at the cost of a large amount of energy; it needs to constantly pump different ions into and out of the cell (ions carry the electric charge). Maintaining the long nerves that may extend a meter (such as the ones from your brain to your spinal cord) is also metabolically taxing as new proteins have to be made constantly and shipped down the nerve. All these processes require energy, and we haven’t even sent any information down axons yet! I would contend that the amount of energy spent maintaining the cell is far more than is actually spent on sending an electrical impulse down an axon.

Ok, so cell maintenance requires a lot of energy. One could then ask the question, “What about the cognitive functions? How much energy do they require?” I think the best way to answer this would be to first ask, ‘How much of the brain is devoted to cognitive function?” If we could say that 50% of the brain was devoted to cognitive function, then we could say 50% of the energy is devoted towards maintaining cognitive function.

The answer to that question is a hard one to pin down. Most of the brain is involved in non-cognitive processing. The brain must recreate visual space from a bunch of pixels in your eye. It computes the location of a sound based on when the sound hits your right ear versus your left ear (within 2 degrees, I think). It maintains your balance, triggers fight-or-flight responses, and decides how your fingers must move to type on a keyboard. Lots of non-cognitive processes are going on.

Furthermore, cognitive abilities are distributed all over the brain. (For those not familiar with brain anatomy, take a peek here for reference for the following descriptions: http://normandy.sandhills.cc.nc.us/psy150/outerbr.gif )

For instance, a brain scan (functional MRI) of people doing arithmetic showed activity in frontal lobe, temporal lobe, and occipital lobe (although activation of the occipital lobe, the site of vision processing, may have had to do with the subjects seeing the math problem). Language processing and generation is located mainly in the temporal lobe and frontal lobe. Decision-making and determining the consequences of actions is thought to occur in the frontal lobe. Generally, the frontal lobe is thought to be a hot seat of ‘cognitive ability,’ but it is not a pure ‘cognitive center.’ It is thought to be involved in non-cognitive decision making (i.e. determining unconscious preference and value). So to ask how much of the human brain is solely dedicated to cognitive tasks, I’d have to hazard a very hand-waving guess of 5%. And that’s a pretty liberal guess. And most of the energy used is spent on maintaining the cells and connections in these areas, not the actual cognitive processing itself.

How does that relate to other animals, primate and non-primate? Primates have a very similar level of cognitive power. They do appear to have a simple form of language, and may even be able to read! ( http://researchnews.osu.edu/archive/chimps.htm ). They can make complicated decisions. Non-primate animals definitely have cognitive abilities as well, such as decision making, risk assessment, and memory formation, though the degree to which these decisions are ‘conscious’ as in humans is quite debatable. I don’t know if I could put a number on how much more brain space and energy is spent on cognition by humans, because it could be the type and amount of connectivity between cells that is more important than the percentage of cells in the brain.

Lastly, I’ll just briefly mention one interesting tidbit of info. The process of being aware of your surroundings apparently requires a lot of energy, which is not surprising. The basic idea is that as you transmit information, it uses some energy. According to one report, “The high resting brain activity is proposed to include the global interactions constituting the subjective aspects of consciousness. Anesthesia by lowering the total firing rates correlates with the loss of consciousness.” That is to say, low conciousness = lower firing rates = less total energy consumed. fMRI really uses a measure of metabolism to determine firing rates:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12806834&query_hl=4

I hope that provides some insights. I don’t know if we know enough to calculate an absolute number. If you have more questions, please do submit them!

-Alex G

from What are the energy requirements of thought?

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Can anyone translate that answer for the scientifically-challenged folks like myself?

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Fingerprint ridges are formed during the third to fourth month of fetal development. The ridges begin to develop on the skin of the thumbs and fingers.

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The earliest dated prints of the ridged skin on human hands were made about 4,000 years ago during the pyramid building era in Egypt.  In addition, one small portion of palm print, not known to be human, has been found impressed in hardened mud at a 10,000-year old site in Egypt.

It was common practice for the Chinese to use inked fingerprints on official documents, land sales, contracts, loans and acknowledgements of debts.  The oldest existing documents so endorsed date from the 3rd century BC, and it was still an effective practice until recent times.  Even though it is recorded that the Chinese used their fingerprints to establish identity in courts in litigation over disputed business dealings, researchers fail to agree as to whether the Chinese were fully aware of the uniqueness of a fingerprint or whether the physical contact with documents had some spiritual significance.

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The Federal Bureau of Investigation established its first fingerprint identification division in the year 1924, with a collection of 810,188 fingerprint files taken mostly from the Leavenworth Penitentiary. These files became more and more important with the emergence of an increasing number of intellectual criminals who crossed all legal and state lines.  Today, the FBI has in possession more than 250 millions different sets of fingerprint records. This collection is enormous and is composed of both civil as well as criminal prints. The civil file includes prints of government employees and candidates for federal jobs.

Source

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Documentary Heaven has a vast number of instructional videos in the following categories:

Source

Fascinating Egyptian Mummies–Unwrapping history with science

This fun and educational four-stage interactive site is based on an exhibition at the Musee de la Civilisation in Quebec City.  Visitors discover different facets of ancient Egyptian cultures.  You must complete three games to enter the last one (which I haven’t achieved yet).

1. Mummification Process.  Put the mummification process in the right order.
2. Canopic Jars.  Place the organs into the right canopic jars.
3. The Weighing of the Heart.  Place the jar that contains a heart as light as the sacred feather on the other side of the scale.
4. Sarcophagi Chamber.  Can’t say what this is becuase I havent completed the first three stages.

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Interesting information about #3

“Ancient Egyptians believed that the deceased had to meet a challenge in order to achieve immortality.  After the deceased declared having committed no faults in life, the heart was weighed.  If it balanced with the feather, this meant that the deceased had lived according to moral standards and could move on to the afterlife, a realm of bliss and delight.  But if the weight of the heart was different from that of the feather, this meant that the deceased had lived in sin and that the heart would be eaten by Ammit, the devourer.”

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Source

via 10 Awesome Flash-Animated Interactive Websites

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• More re: Treasures – World’s Cultures from British Museum in western Canada (allaboutegypt.org)
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Questions

1. How did the Ancient Egyptians calculate when the River Nile would flood each year?
2. From what did the Mayans believe the world to be made?
3. Which Ancient Greek god was thought to cause earthquakes?
4. Name the two forces which Confucius believe were central to harmony in the Universe.
5. Name one of the two influential medical books written by IbnSina.
6. Name the four most important universities founded during the 12th-13th centures.
7. What part of Tycho Brahe’s body was cut off in a duel?
8. What two methods did Vesalius use to obtain specimens for this study of anatomy?
9. Vesalius wrote one of the greatest scientific books ever published.  What was it’s title?
10. What is the name given to the tiny blood vessels that connect veins and arteries?
11. Galileo was threatened with torture unless he denied which claim?
12. Name one of the founding members of the Royal Society.
13. What incident is said to have been the starting point for Isaac Newton’s theory of gravitation?
14. Linaeus developed a method of classifying plants called “binomial nomenclature”.  What does it mean?
15. Which book proposed that species had developed over long periods of time?
16. Name the two different theories concerning the structure of the earth preferred by Werner and Hutton.
17. What is the name given to the supercontinent by Wegener?
18. What was the name of the ship on which Charles Darwin sailed to South America?
19. What is the modern name for the gas that Joseph Priestley called “dephlogisticated gas”?
20. What is the name given to Mendeleev’s grouping of elements?
21. What is the name of the device Ewald von Kleist designed for storing static electricy?
22. What apparatus did Benjamin Franklin use to prove that lightning is a form of electricity?
23. Which measurement of electricity is named after an 18th century scientist?
24. Which process, discovered by Edward Jenner, is considered to be one of the most important advances ever made in medical science?
25. Who was the first person to receive two Nobel prizes?
26. On which plant did Mendel perform most of his experiments?
27. Why did Niels Bohr go to live in the USA in 1943?
28. Who was the first woman to be appointed assistant to the Court Astronomer in 1787?
29. Why was Mary Somerville’s first scientific paper submitted to the Royal Society by her husband?
30. In 1927, Georges Lemaitre propsed an idea that explained the origins of the Universe.  What is it now known as?

Answers

1. They studied the position of the moon and the stars.
2. They believed that the world was made from the back of a giant crocodile living in a pond.
3. Poseidon
4. Yin and Yang
5. The Canon and The Cure
6. Bologna, Oxford, Cambridge, and Paris
7. His nose
8. Grave robbing and taking bodies from the gallows.
9. The Fabric of the Human Body
10. Capillaries
11. The Earth moved around the Sun.
12. Christopher Wren, Samuel Pepys
13. He saw an apple fall from a tree.
14. It means that each plant has two names. One indicates its genus, the other its species.
15. The Natural History by Georges de Buffon
16. The “Neptunist” theory and the “Plutonist” theory.
17. Pangaea
18. HMS Beagle
19. Oxygen
20. The Periodic Table
21. The Leiden Jar
22. A kite fitted with a metal key.
23. The volt, after Alessandro Volta
24. Vaccination
25. Marie Curie
26. The pea plant.
27. To escape the Nazis.
28. Caroline Herschel.
29. At that time, women were banned from the organization.
30. The Big Bang Theory

When I look in the mirror and see the wrinkles and age spots starting to form, I wonder what I will look like in five or ten years.  Today I found out.  Yikes!

The Face Transformer will age your face make it look like a child again (wouldn’t we all like to do that).  Just follow the instructions.  At the end, click on the ‘transform’ list and watch what happens to your photo.  Try it for fun.

Note: It works better on Internet Explorer.

Just sharing what I received in an email…

Icebergs in the Antarctic area sometimes have stripes, formed by layers of snow that react to different conditions.  Blue stripes are often created when a crevice in the ice sheet fills up with meltwater and freezes so quickly that no bubbles form.  When an iceberg falls into the sea, a layer of salty seawater can freeze to the underside.  If this is rich in algae, it can form a green stripe.  Brown, black and yellow lines are caused by sediment picked up when the ice sheet grinds downhill towards the sea.

The water froze the instant the wave broke through the ice.  That’s what it is like in Antarctica where it is the coldest weather in decades.  Water freezes the instant it comes in contact with the air.  The temperature of the water is already some degrees below freezing.

Look how the wave froze in mid-air…

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At the moment I’m developing “thought knots” from trying to wrap my understanding around all the possibilities emerging from the hi-tech research that’s trying to hack into our brains–and those of animals (see my post link below).

Now, the US Army is trying to use “thought helmets” to transmit brain waves which would be translated into words in other soldiers’ headphones.

The US Army has recently awarded a five-year $4 million contract to researchers from the University of California at Irvine (led by UCI´s Mike D´Zmura), Carnegie Mellon University, and the University of Maryland to study the concept.

Because the brain is a complex system and generates such large amounts of data, researchers must also make improvements in computing power. Soldiers will also have to be trained to think “loudly” to make it easier for the system to pick out their words from the brain´s background noise. Also, every individual´s EEG signals are a little different, so users and computers will have to be calibrated so that computers recognize each person´s unique mental pattern.

Read more here

* See my related post on dream research [Link]

Love is in the air–literally. When the Aedes aegypti mosquitoes are looking for a mate, they create an overtone.  How did researchers figure this out?

First, the insects were anesthetized. “You make them a little bit chilly,” Hoy says, “then they don’t fly or walk around.” Next, he and his colleagues applied a small amount of superglue to the backs of the test mosquitoes, then affixed them to a tiny tether and suspended them in the air.

Once the mosquitoes began to beat their wings and produce their gender-specific flight tones, the scientists moved the insects close to each other.

The duet they produce (as you’ll hear in the audio) matches the pitch in the Morris Albert song “Feelings.”

[Audio]

[Video]

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This anatomical imagery is detailed inspiration.  Some are beautiful and whimsical,, while others are quite  grotesque.

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“Drawn mainly from the collections of the National Library of Medicine, Dream Anatomy shows off the anatomical imagination in some of its most astonishing incarnations, from 1500 to the present.”

Link

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Q: About your dreams: how do you interpret them?  Are they in color or black and white?  Have they ever helped you solve a problem or led to a published story/poem?

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I love photographers who are able to lift me from my everyday unremarkable events and translate me into a ‘look closer’ realm.  According to this website, each grain of sand is a tiny work of art.  And after you look at the pictures, I think you’ll tend to agree.