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Showing posts with label health news. Show all posts
Showing posts with label health news. Show all posts

Wednesday, August 17, 2011

Seeing eye to eye is key to copying, say scientists


Imitation may be the sincerest form of flattery but how do our brains decide when and who we should copy? Researchers from The University of Nottingham have found that the key may lie in an unspoken invitation communicated through eye contact.



In a study published this week in the Journal of Neuroscience, a team of scientists from the University's School of Psychology show that eye contact seems to act as an invitation for mimicry, triggering mechanisms in the frontal region of the brain that control imitation.

The results could be the first clues to understanding why some people, such as children with autism, struggle to grasp when they are expected to copy the actions of others in social situations.

Dr Antonia Hamilton, who led the research, said: "Many studies have looked at copying and imitation in terms of 'mirror neurons', which are believed to be specialised parts of the human brain that implement imitation. However, we also know that imitation is carefully controlled — people don't imitate everything they see, and only copy what's important.

"Our previous research has shown that when somebody makes eye contact with you, you are more likely to copy them. So eye contact seems to act as a message that says "Copy me now". This recent study aimed to see what happens to that signal in the brain."




The team of psychologists, which also included doctoral student Yin Wang and Dr Richard Ramsey, used functional magnetic resonance imaging (fMRI) to scan the brains of volunteers while they watched videos of an actress who sometimes would make eye contact with them while opening or closing her hand. The participant was told they should open their own hand whenever they saw the actress move her hand so in some trials the participant was copying the actress and in other trials they were not.

Because previous behavioural measurement such as response time revealed that the participant unconsciously copied the actress faster when the actress provided eye contact, the scientists analysed the brain imaging data to find which brain areas controlled the decision to copy. The analysis used a new mathematical method called dynamic causal modelling to compute the information processing in the brain, which has never been applied to imitation before.

The data showed that mirror neuron brain regions do play a role in the copying task. More importantly though, it revealed that these regions are controlled by the medial prefrontal cortex, an area of the brain associated with planning complex cognitive behaviours, expressing personality, decision-making and responding to social situations.

Dr Hamilton added: "Previous studies have shown that this medial prefrontal brain region is active in many social situations but responds less in people with autism, which explains why children on the autistic spectrum might not copy at the right time.

"Understanding the control of imitation has implications for many other areas of psychology too. For example, are teenagers whose prefrontal cortex is less developed more easily led to copy risky, dangerous or illegal behaviour such as imitating rioters? Could increasing the amount of eye contact between children and teachers lead to better learning by imitation? Would better control of imitation help children with autism to more effectively learn and interact? We plan further research to address these questions."

Provided by University of Nottingham


Tuesday, July 12, 2011

Researchers connect neurons to computers to decipher the enigmatic code of neuronal circuits


Machine logic is based on human logic. But although a computer processor can be dissembled and dissected in logical steps, the same is not true for the way our brains process information, says Mark Shein of Tel Aviv University's School of Electrical Engineering.

Doctoral student Shein and his supervisors, Prof. Yael Hanein of the School of Electrical Engineering and Prof. Eshel Ben-Jacob of the School of Physics and Astronomy, want to understand the brain's logic. They have developed a new kind of a lab-on-a-chip platform that may help neuroscientists understand one of the deepest mysteries of our brain –– how neuronal networks communicate and work together. The chip was recently described in an issue of the journal PLoS ONE.

Within it, Shein has applied advanced mathematical and engineering techniques to connect neurons with electronics and understand how neuronal networks communicate. Hoping to answer ultimate questions about how our neuronal circuits work, the researchers believe their tool can be also used to test new drugs. It might also advance artificial intelligence and aid scientists in rewiring artificial limbs to our brain.

Shedding light on a black box

There are relatively simple neural "firing" patterns that can be measured with sensory organs like the ears or eyes, but researchers know little about deep thought processes. Could the brain's electrical signals reveal the basis of thought itself?

"When we look at the neuronal networks operating in the ears or eyes, we have some idea about the coding schemes they utilize," explains Shein. A researcher can apply a stimulus such as a bright light, for example, and then monitor responses in the eye's neurons. But for more complex processes, like "thinking" or operating different sensory inputs and outputs together, "we are basically looking into a black box," he says.

The brain is composed of a daunting number of circuits interconnected with other countless circuits, so understanding of how they function has been close to impossible. But using engineered brain tissue in a Petri dish, Shein's device allows researchers to see what's happening to well-defined neural circuits under different conditions. The result is an active circuitry of neurons on a man-made chip. With it they can look for patterns in bigger networks of neurons, to see if there are any basic elements for information coding.



Investigating the activity of single neurons is not enough to understand how a network functions. With nanotechnological systems and tools, now researchers can explore activity patterns of many neurons simultaneously. In particular, they can investigate how several groups of neurons communicate with each other, says Shein.

The hierarchy of the brain

With these network engineering techniques, the scientists cultured different sized networks of neuronal clusters. Once they looked at these groups, they found rich and surprising behaviors which could not be predicted from what scientists know about single neurons.

The researchers were also able to measure patterns from nerve activity, at nodes where a number of nerves converged into networks. What they detected appears to show that neural networks have a hierarchical structure — large networks are composed of smaller sub-networks. This observation, and a unique setup using electrodes and living nerves, allowed them to create hierarchical networks in a dish.

The brain's circuits work like codes. They can see the patterns in the networks and simplify them, or control connectivity between cells to see how the neuronal network responds to various chemicals and conditions, the scientists report. One theory, proposed by Prof. Ben-Jacob, is that the human brain stores memories like a holograph of an image: small neural networks contain information about the whole brain, but only at a very low resolution.

So far the researchers are able to reveal that clusters of as few as 40 cells can serve as a minimal but sufficient functional network. This cluster is capable of sustaining neural network activity and communicating with other clusters. What this means exactly will be the next question.

Provided by Tel Aviv University



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