Amygdala detects spontaneity in human behaviour

Study of jazz musicians reveals how the brain processes improvisations 

 

A pianist is playing an unknown melody freely without reading from a musical score. How does the listener’s brain recognise if this melody is improvised or if it is memorized? Researchers at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig investigated jazz musicians to discover which brain areas are especially sensitive to features of improvised behaviour. Among these are the amygdala and a network of areas known to be involved in the mental simulation of behaviour. Furthermore, the ability to correctly recognise improvisations was not only related to the musical experience of a listener but also to his ability to take the perspective of someone else. 

 

The ability to discriminate spontaneous from planned (rehearsed) behaviour is important when inferring others’ intentions in everyday situations, for example, when judging whether someone’s behaviour is calculated and intended to deceive. In order to examine such basic mechanisms of social abilities in controlled settings, Peter Keller, head of the research group “Music Cognition and Action” at the Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig and his research associate Annerose Engel investigate musical constellations ranging from solos and duos to large musical ensembles. In a recent study, they investigated the brain activity of jazz musicians while these musicians listened to short excerpts of improvised melodies or rehearsed versions of the same melodies. The listeners judged whether each heard melody was improvised.

 

Amygdala activation during listening to improvised melodies (compared to listening to imitated melodies). 

 

“Musical improvisations are more variable in their loudness and timing, most likely due to irregularities in force control associated with fluctuations in certainty about upcoming actions—i.e., when spontaneously deciding what to play—during improvised musical performance”, explains Peter Keller. The amygdala, part of the limbic system, was more active while listening to real improvisations and was sensitive to the fluctuations of loudness and timing in the melodies. Thus, the amygdala seems to be involved in the detection of spontaneous behaviour, which is consistent with studies showing an involvement of this structure when stimuli are difficult to predict, novel or ambiguous in their meaning.

Increased activation in the frontal operculum (left), the pre-supplementary area (middle) and the anterior insula (right) when listening to melodies judged as being improvised.
 
If a melody was judged as being improvised, regardless of whether this was in fact the case, stronger activity was found in a network which is known to be involved in the covert simulation of actions. This network comprised the frontal operculum, the pre-supplementary area and the anterior insula.
“We know today that during perception of actions, similar brain areas are active as during the execution of the same action”, explains Annerose Engel. “This supports the evaluation of other people’s behaviour in order to form expectations and predict future behaviour.” If a melody is perceived as being more difficult to predict, for example, because of fluctuations in loudness and timing, stronger activity is most likely to be elicited in this specialised network.
A further observation the researchers made may be related to this: Not only musical experience but also the capacity to take someone else’s perspective played an important role in judging spontaneity. Jazz musicians who had more musical expertise in playing the piano and playing with other musicians, as well as those who more often described themselves as trying to put themselves in someone else’s shoes were best at recognizing whether a melody was improvised or not.

Source Max-Planck-Gesellschaft

Carlo Ratti: Architecture that senses and responds

With his team at SENSEable City Lab, MIT's Carlo Ratti makes cool things by sensing the data we create. He pulls from passive data sets -- like the calls we make, the garbage we throw away -- to create surprising visualizations of city life. And he and his team create dazzling interactive environments from moving water and flying light, powered by simple gestures caught through sensors.

Osama bin Laden: how DNA identified his body

Achieving a satisfactory identification of the world's most wanted man is not, it turns out, a simple matter. According to the US government, the body of Osama bin Laden, killed during a raid on a compound in Abbottabad, Pakistan, on 2 May, was identified by comparison to photographs, confirmation from one of his wives at the compound, facial-recognition software, and – the gold standard for identification – DNA analysis.

John Brennan, Assistant to the President for Homeland Security and Counterterrorism, said the DNA evidence provided a match with "99.9 per cent confidence". That would require the comparison of DNA from the body with that of people known to be related to bin Laden. Bin Laden had no full siblings, but more than 50 half-siblings and up to 24 children.

Using DNA from many half-siblings could produce a DNA match of greater than 90 per cent confidence, but it would be difficult to get as high as 99.9 per cent without a closer relative says Rhonda Roby, a forensic geneticist at the University of North Texas Health Science Center, Fort Worth. Roby, who led the team using DNA evidence to identify the remains of people killed in the 9/11 attacks in 2001, says that the statistical analysis based on DNA from half-siblings is more complex and less reliable than analysis based on DNA from a closer relative like a parent or child.

Reports indicate that one of bin Laden's sons was also killed in the raid, possibly 20-year-old Hamza bin Laden. Roby says DNA from a son and several half-siblings could confirm Osama's identity with 99.9 per cent accuracy. 

Full paternity trio?

If, however, the government was able to obtain DNA from bin Laden's body, his son and also that son's biological mother – who might have been at the compound during the raid, it could perform DNA profiling with a "full paternity trio", assuring 99.9 per cent accuracy, Roby says.

The provenance of the DNA used in the comparison is unknown, as is the nature of the test itself. However, it is likely that forensic scientists analysing bin Laden's DNA used the polymerase chain reaction to amplify between 13 and 16 key regions called short tandem repeats (STRs), then compared the pattern of these with the same STRs from that of his relatives.

The agency responsible for conducting the analysis is also unconfirmed: media reports have named both FBI and the CIA. Several sources suggested that DNA was subpoenaed from the body of a half-sister of bin Laden, when she reportedly died at Massachusetts General Hospital in Boston, but the hospital was unable to confirm the report. "There is no evidence she was even here," says spokesperson Sue McGreevey.

FBI special agent Greg Comcowich would not confirm or deny any investigative steps the FBI has taken. When asked whether the agency would release any further information on the DNA analysis, he replied: "Not that I'm aware of."

Source  New Scientist