Tuesday, March 29, 2011
All about the brain
Head or heart?
If you’re eating or particularly squeamish, you might want to skip this one. Today we believe the brain is the seat of our conscious being, but it wasn’t always so – in previous times the heart held that title.
You can see an example of that thinking through mummies from ancient Egypt, where dead bodies were carefully dried out so they wouldn’t decay easily. When preparing the body, the special priests who carried out the task would remove most of the internal organs.
And to remove the brain without messing up the face, they would stick hooked instruments into the nostrils and pull out bits of the tissue from inside the head (nice work if you could get it). But they left the heart in place, believing it to be the site of a person’s being and intelligence.
Mind-reading, sort of
Imagine if someone could read your mind – how weird would that be? Well it turns out that with a lot of expensive equipment, and under certain conditions, it can be done. Sort of, and in a really basic way.
The approach uses a technique called functional magnetic resonance imaging, or fMRI. It measures changes in blood flow in different parts of the brain, which is a signal of brain activity.
Scientists have been able to hook volunteers up to fMRI, then using computers to analyse the data on their brain activity, they worked out with high accuracy what images the volunteers were looking at on a computer, or what images they were storing in their short-term, “working” memory after viewing them. It’s thankfully a long way off a computer rummaging your inner thoughts, but it’s still pretty amazing that scientists can link specific brain activity to what a person is thinking about.
When you think of the word ‘brainy’, who springs to mind? Maybe Albert Einstein? He’s widely considered to have been a genius, but what made him so? Years after his death, scientists based in Canada examined his preserved brain to see if there were any clues to help us understand how Einstein could get his head around the complex mathematical concepts of spacetime and relativity.
Interestingly, they found that Einstein’s brain was not actually the size of Leitrim – in fact it was a little smaller than the average human adult brain.
But they did claim to see unusual features in his parietal lobes, which are areas of the brain involved in maths, thinking in shapes and imagining movement.
And another study, this time in California, found that one area had a relatively large number of glial cells. But was Einstein born this way, or did all that thinking about maths and the universe change his brain?
about 7,000 BC
Prehistoric brain surgery As far back as the Stone Age, surgeons used to cut holes in people’s skulls in a procedure known as trepanation. Human remains from thousands of years ago have been discovered with such holes – and some even showed signs of healing, so they must have survived the early neurosurgery. Ouch.
Getting on your nerves Galen was a big name in ancient medicine, and he was interested in anatomy. He worked out that tying off particular nerves could paralyse, and he also saw the brain as being an important controller.
Hot wax breakthrough Leonardo Da Vinci was not just an artist, but he also liked to research science and the body. So he combined the two passions by putting hot wax into the brain of an ox then letting it cool. That made a cast of the “ventricles”, or cavities inside the brain.
Getting to grips with brain anatomy In 1664 an English doctor called Thomas Willis published a book that compared the brain anatomy of humans and other animals. Containing drawings by architect Christopher Wren, it is thought to have laid the foundations for the fields of neurology and neuroanatomy.
An unfortunate change in personality Sometimes we learn about what an area of the brain does by seeing what happens when it goes wrong. In the mid-19th century an accident sent a metal rod through the brain of railroad worker Phineas Gage. He survived but his pre-frontal cortex was damaged and his personality changed drastically, and we now know that area of the brain is linked with personality.
Finding your voice The part of your brain that helps you talk and understand language is called Broca’s area, named after the 19th century French doctor who noticed that damage in this region was linked to speech problems.
Getting to know the brain cell You have billions of brain cells called neurons in your head that wire up and talk to each other to process information and make your body work. Santiago Ramón y Cajal discovered neuron in the late 19th century. The observation no doubt prompted a few of his own brain cells to wire together too, and he shared a Nobel Prize for his efforts.
A rush of blood to the head Brain breakthroughs came thick and fast in the 1920s. Researchers discovered glial cells in the brain that we now know perform important functions, they found that neurons pass each other messages using chemicals called neurotransmitters and they even saw brainwaves in the form of electrical readouts.
Poke that neuron Since around the 1940s, surgeons have been physically stimulating tissue deep in the brain in order to treat symptoms in patients. By inserting or implanting a tiny electrode to a specific portion of the brain it’s possible to electrically activate or block particular neurons. One of its more recent applications has been in Parkinson’s disease, to help reduce tremors.
Memory man Another famous patient in the history of brain science is Henry Gustav Molaison, or HM. He had epilepsy and in 1953 a surgeon treating it removed much of HM’s hippocampus as well as other parts of his brain. It stopped the seizures but HM lost many aspects of his memory, and studies of his case led to a better understanding of how human memory works. HM, whose mother was from Ireland, died in 2008.
Mind the gap – finding the synapse By the mid-20th century microscopes were getting pretty good, and in the 1950s scientists saw the synapse, a gap between brain cells. The cells pass messages to each other across it.
Can you hear me now? In the 1960s, researchers figured out how to implant electrodes in the cochlea of the human ear and electrically activate certain nerves involved in hearing. Such cochlear implants have been widely available since the 1980s and can help some people with hearing problems.
Alzheimer drug The 1990s, which was designated the “decade of the brain”, saw the first drug being approved to treat the symptoms of Alzheimer’s disease, in which cells in the brain die, affecting memory. The drug aimed to boost levels, in the brain, of the chemical acetylcholine, which is involved in memory. Newer drugs have now replaced it, and today scientists are working on several approaches to diagnose and treat Alzheimer’s disease.
Brain genes Now that scientists are getting a better handle on the genes we humans have and how they work, they are looking at the kinds of variations in those genes that contribute to brain conditions. Some are vastly complicated, like schizophrenia, and recent studies of the human genome suggest that, in some cases at least, having extra or missing copies of particular genes could increase the risk of a person developing the condition.
In an average-sized adult, the brain makes up only around two per cent of the body weight but hogs about 20 per cent of the energy and oxygen intake
Bionic eye for blindness An artificial implant for the retina at the back of the eye should be available through some hospitals later this year. Trials showed that when blind people used it, many could recognise large letters and find objects.
What’s your earliest memory? For most people it’s something that happened around the time they were aged three or four
Your brain contains about 100 billion neuron cells, which wire together to form hundreds of trillions of connections
You can’t tickle yourself because your brain anticipates the touch from your own hand and there’s no element of surprise
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