Picking our brains: Nine neural frontiers

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THE BIG BRAIN QUESTIONS

The human brain is the most astoundingly complex structure in the known universe. Yet we are starting to unravel some of its mysteries, thanks to advances in brain imaging, genetics, stem cell research and more. We explore the latest findings from the hottest topics in neuroscience.

1. What are memories made of?

MEMORIES are the basic stuff of thought. We access our stores of knowledge every time we perform a task, communicate through speech or formulate the simplest concepts. Yet the physical form of memory has long been mysterious. What changes occur in the brain when a new memory is encoded?

One thing we do know is that memory formation involves the strengthening of synaptic connections between nerve cells. Using sea slugs, which have a relatively simple nervous system, a team led by Kelsey Martin at the University of California, Los Angeles, last year became the first to watch memories being made, in the form of new proteins appearing at the synapses (Science, vol 324, p 1536).

Where, though, is knowledge stored in the complex brains of mammals? Short-term memories, such as a telephone number about to be used, seem to be stored in two small curled-up structures called the hippocampi, buried deep in the brain's two hemispheres. In 2008 Courtney Miller and David Sweatt at the University of Alabama in Tuscaloosa showed in mice that during the first hour after a memorable event there were chemical changes to the DNA of neurons in this area, altering the proteins produced. Over the subsequent week, there were similar changes to the genes of neurons in the cortex. These changes seemed to be permanent, indicating that long-term memories are stored there (Neuron, volume 53, p 857). The pair think they watched short-term memories form in the hippocampus, which then became long-term memories in the cortex.

2. Can we regenerate the brain?

YOU were born with all the brain cells you'll ever have, so the saying goes.

So much for sayings. In the 1990s, decades of dogma were overturned by the discovery that mammals, including people, make new neurons throughout their lives. In humans, such "neurogenesis" has been seen in two places: neurons formed in the olfactory bulb seem to be involved in learning new smells, while those born in the hippocampus are involved in learning and memory.

The discovery that new neurons can integrate into the adult brain raises intriguing possibilities. Could the process be harnessed to treat diseases of the brain, such as Parkinson's and Alzheimer's?

The trick will be in replacing diseased cells with just the right kind of neuron, says Jeff Macklis, who studies neurogenesis at the Massachusetts Institute of Technology. By some estimates, the nervous system is made up of 10,000 different kinds of neuron.

This complexity means you can't just hijack any old cell produced by natural neurogenesis. However, there may be other ways of growing new neurons to order.

3. What are mirror neurons?

"WHEN you're smilin', the whole world smiles with you," sang Louis Armstrong. He could have been referring to what some consider one of the greatest recent discoveries of neuroscience: mirror neurons.

Discovered in macaques in the 1990s, these cells were spotted when researchers made recordings from microelectrodes placed in the animals' brains as they performed various tasks. While many neurons fired when the animal performed an action, a subset also fired when the animals saw the researcher perform the same action, with different groups of mirror neurons for different actions.

Neuroscientists have speculated that in people, mirror neurons could represent the neural basis of empathy. They could also contribute to imitation and learning, and perhaps even language acquisition.

It has been hard to find out if people have mirror neurons, but MRI scans have shown that certain areas of the brain - dubbed mirror systems - "light up" when we perform and watch the same action. Numerous studies have shown that people with more activity in their mirror systems seem to be better at understanding other people's emotions. Conversely, less activity in mirror systems has been linked to autism and also with psychopathy - different conditions that are both noted for low levels of empathy. Nina Bien's team at Maastricht University in the Netherlands recently identified inhibition mechanisms that hint at how we can mentally imitate an action without actually performing it (Cerebral Cortex, vol 19, p 2338).

4. How many ways can we be conscious?

YOU might think consciousness is like a light switch, either on or off. But the true picture now seems rather murkier, challenging our notions of awareness and free will, as well as raising issues of consent in coma patients.

People used to think just three states of consciousness existed, says Adam Zeman of the Peninsular Medical School in Exeter, UK. "You're either awake or asleep - and if you're asleep you're either in dream or non-dream sleep."

But brain imaging suggests there are more. Take sleepwalking, which affects as many as 1 in 20 adults. "The sleepwalking brain is literally in a half-awake, half-asleep state," says Zeman. Researchers once manoeuvred a sleepwalker into a brain scanner, and while they saw that much of the cortex - involved in awareness and consciousness - was offline, other brain areas were active, including those linked with emotion.

Similar overlaps might explain other weird states of consciousness. In dreaming sleep - also known as REM sleep - we lie still because an area of the brainstem called the pons blocks signals to the muscles. People with REM behaviour disorder lose this inhibition and physically act out their dreams. The opposite condition, known as sleep paralysis, occurs if people wake up while still unable to move.

[edit on 10-4-2010 by predator0187]

5. How strong is the mind-body link?

IF YOU'RE unlucky enough to be staying in hospital, try to get a room with a view. You may recover quicker if you overlook a grove of trees rather than a brick wall.

The study of the links between mind and body is as old as the practice of medicine. Wise doctors know, for example, to probe the mental state of a patient whose symptoms are hard to explain physically. And we have all heard of cases where a bereavement or divorce seems to have triggered the onset of illness.

Yet considering how much we take such links for granted, their mechanisms remain mysterious. Why are some diseases more influenced by mental state than others? What's behind the mind-boggling placebo effect? Could we ever learn to think ourselves well?

Many of these effects seem to be mediated by the immune system. Severe stress has been shown to reduce immune cell activity, both in the test tube and in people. There seem to be several ways in which the brain influences the immune system, from chemical mediators to direct neural control. One branch of the vagus nerve connects the brain to a key regulator of immune functioning, says Kevin Tracey of the Feinstein Institute for Medical Research in Manhasset, New York. "Signals that originate in the brain travel down the vagus nerve where they change the behaviour of immune cells in the spleen," he says

6. Why are some people smarter?

AT EINSTEIN's autopsy in 1955, his brain was something of a disappointment: it turned out to be a tad smaller than the average Joe's. Indeed, later studies have suggested a minimal link between brain size and intelligence. It seems brain quality rather than quantity is key.

One important factor seems to be how well our neurons can talk to each other. Martijn van den Heuvel, a neuroscientist at Utrecht University Medical Center in the Netherlands, found that smarter brains seem to have more efficient networks between neurons - in other words, it takes fewer steps to relay a message between different regions of the brain. That could explain about a third of the variation in a population's IQ, he says.

Another key factor is the insulating fatty sheath encasing neuron fibres, which affects the speed of electrical signals. Paul Thompson at the University of California, Los Angeles, has found a correlation between IQ and the quality of the sheaths (The Journal of Neuroscience, vol 29, p 2212).

We still don't know exactly how much genes contribute to intelligence, with various studies coming up with estimates ranging from 40 to 80 per cent. This wide range of estimates might have arisen because genes contribute more to IQ as we get older, according to a study published last year. By comparing the intelligence of 11,000 pairs of twins, Robert Plomin of King's College London found that at age 9, genes explain 40 per cent of the variation, but by 17 they account for roughly two-thirds (Molecular Psychiatry, DOI: 10.1038/mp.2009.55).

7. Can mental illness make you creative?

"THERE is no great genius without a tincture of madness." So wrote the Roman philosopher Seneca, nearly 2000 years ago.

Today it is routine for creative geniuses from history to get retrospective diagnoses of mental illness - some more believable than others. Schizophrenia and other forms of psychosis are the most common illnesses cited, with Newton and Einstein among the most famous subjects. Vincent van Gogh and Virginia Woolf have been linked with bipolar disorder.

Few would argue that full-blown psychosis is conducive to creative accomplishment, but perhaps a little bit helps. Psychiatrists view mental health as a spectrum, with serious illness at one end and "normality" at the other. Perhaps those in the middle have enhanced creative tendencies.

Some evidence comes from considering the relative dominance of the right and left hemispheres of the brain. There is much dubious pop psychology written about "right-brain people" and "left-brain people", but it is accepted that the left side is mainly involved in language and logical analysis, while the right side is more involved in creative thought. Various techniques for studying dominance do seem to show that people with schizophrenia have more right-brain activity.

8. How powerful is the subconscious?

SUBCONSCIOUS thought is the brain's dumb autopilot - the chump behind repetitive tasks, Freudian slips and all the other things we do "without thinking". That was certainly the prevailing view in the 20th century, but the subconscious has lately gone up in the world. It takes centre stage in creativity, puts the "eureka!" into problem-solving, plays a crucial role in learning and memory, and it's even better at making tough decisions than rational analysis is (New Scientist, 1 December 2007, p 42).

It was in the 1980s that the late neuroscientist Benjamin Libet saw a spark of brain activity 300 milliseconds before subjects consciously chose to twitch a finger. We now know the unconscious decision happens even earlier. In 2008, John-Dylan Haynes at the Bernstein Center for Computational Neuroscience in Berlin, Germany, found brain activity up to 10 seconds before a conscious decision to move (Nature Neuroscience, vol 11, p 543).

Stanislas Dehaene, director of the Cognitive Neuroimaging Unit at INSERM, France, has elegantly revealed the subtle interplay between subconscious and conscious thought. In his experiment, volunteers saw a word flashed onto a screen, followed almost immediately by a picture, which masks conscious perception of the word. As the time interval between the two increases, the word suddenly pops into consciousness - accompanied by characteristic activity on a brain scan. This usually happened when the interval reached around 50 milliseconds, but when emotional words such as "love" or "fear" were used, it happened a few milliseconds earlier. It is as though the decision about the word's importance and attention-worthiness was taken by the subconscious itself

9. Can we make a conscious machine?

CHALLENGES don't get much bigger than trying to create artificial consciousness. Some doubt if it can be done - or if it ever should. Bolder researchers are not put off, though. "We have to consider machine consciousness as a grand challenge, like putting a man on the moon," says Antonio Chella at the University of Palermo in Italy and editor of the International Journal of Machine Consciousness. The journal was launched last year, a sign of the field's growing momentum. Another landmark is the recently developed "Conscale", developed by Raúl Arrabales of the Carlos III University of Madrid in Spain to compare the intelligence of various software agents - and biological ones too.

Perhaps the closest a software bot has come so far is IDA, the Intelligent Distribution Agent built in 2003 by Stan Franklin at the University of Memphis in Tennessee. IDA assigns sailors in the US navy to new jobs when they finish a tour of duty and has to juggle naval policies, job requirements, changing costs and sailors' needs.

Like people, IDA has "conscious" and "unconscious" levels of processing. At the unconscious level she deploys software agents to gather data and process information. These agents compete to enter IDA's "conscious" workspace, where they interact with each other and decisions get made. The updated Learning IDA, or LIDA, was completed this year. She learns from what reaches her consciousness and uses this to guide future decisions. LIDA also has the benefit of "emotions" - high-level goals that guide her decision-making.


[edit on 10-4-2010 by predator0187]

I had to post this because this is our future of neurological studies. This is very important to all of us and I bet you all of us has at least one of these questions that are asked in here.

This will tell you what and how we are studying them. Very important stuff and very ground breaking.

I hope everyone enjoys and hopefully some of their questions can be answered.

Any thoughts?

Pred...

S AND F! Great thread OP.

this also brings up the topic of neuroplasticity, how the brain changes.

I personally just learned(made a memory) on how we memories are made in the form of proteins-thank you op! lol, i should get more protein in my diet.

I personally want to change my self, especially behavior and I want to be able to connect to my memories some that I know are still locked away because i haven't found the key, its strange sometimes i remember things of no relation to my current state that are from years ago or very different states in my life that had no relation (no connection at all those synapses) its like the memories leaped one side of my brain to the other and made a spontaneous occurrence, it was surreal and crazy.

like wth did that come from oh i remember that wooow

[edit on 10-4-2010 by togetherwestand]

Just more evidence (or perhaps old evidence?) that consciousness is outside brains.

S&F for a good thread.

reply to post by togetherwestand


Thanks.

I just read a book about neuroplasticity, I think it was called 'The brain that changed itself.' It was interesting to read the breakthroughs that have been done on that subject. They say it was the biggest breakthrough in the last 400 years finding out the brain was plastic.

Very interesting stuff.

Pred...