An image of the human brain.
(photo credit: REUTERS)
The brain is a very complex network containing some 100 billion neurons and 100 trillion synapses between the neurons. To cope with its enormous complexity and understand how the brain works and eventually forms our conscious mind, science uses advanced mathematical tools. Ultimately, scientists seek to understand how a global phenomenon such as consciousness can emerge from our neuronal network.
A team of Bar-Ilan University physicists led by Prof. Shlomo Havlin and Prof. Reuven Cohen used network theory to deal with this complexity and to determine how the structure of the human cortical network can support complex data integration and conscious activity. The gray area of the human cortex comprised of neuron cell bodies was scanned with MRI imaging and used to form 1,000 nodes in the cortical network. The white matter of the human cortex, the neuron bundles, were scanned with diffusion-weighted magnetic resonance imaging (DTI) imaging, forming 15,000 links or edges that connected the network’s nodes. In the end of this process, their network was an approximation of the structure of the human cortex.
Their research, recently published in New Journal of Physics, attempts to decompose the structural layers of the cortical network to different hierarchies, enabling the identification of the network’s nucleus from which our consciousness could emerge.
Previous studies have shown that the human cortex is a network with many local structures and some shortcuts from global structures that connect faraway areas (similar to the difference between local buses and cross-country trains). The cortex also has many hubs, which are nodes that have a high number of links (like central stations), that are also strongly interconnected between themselves, making it easy to travel between the brain’s information highways.
Nir Lahav, the lead author of the study, explained: “To examine how the network’s structure can support global emerging phenomena, like consciousness, we applied a network analysis called k-shell decomposition. This analysis takes into account the connectivity profile of each node, making it easy to uncover different neighborhoods of connections in the cortical network we called shells.
We peel off different shells of the network to get the most connected area of the network, the nucleus… For the first time we can build a comprehensive topological model of our cortex.”
The connection between brain activity and consciousness is still a great mystery, said Lahav.
“The main hypothesis today is that to create conscious activity, the brain must integrate relevant information from different areas of the network. According to this theory, led by University of Wisconsin Prof. Giulio Tononi, if the level of integrated information crosses a certain limit, one enters consciousness, which according to this model suggests that consciousness depends on both information integration and information segregation.
“Profound questions need a profound answer that can usually be found only in physics, which tries to uncover the basic laws of nature by constructing general mathematical equations that can describe as many natural phenomena as possible. These mathematical equations reveal fundamental aspects of reality. If we really want to understand what consciousness is and how the brain works, we have to develop the mathematical equations of our brain and our conscious mind. We are not there yet, in fact we are quite far away from this goal, but I feel that this should be our ‘holy grail’ and we have already begun the process of getting there,” Lahav concluded.
SAFETY CHILD SEATS TO SCHOOL IN TAXIS
Children who travel in taxis to and from school will be permitted to do so only if they occupy a suitable child safety seat, the Knesset’s Children’s Rights Committee has decided. Many children use taxis to get to and from school under Education Ministry supervision, said MK Yifat Shasha Biton (Kulanu), the committee chairman at a meeting on the subject recently. After amending the existing law, she added that the committee will change the law again to require all children to be placed in suitable safety seats when they travel in taxis. Today, there is no such requirement.
Taxis take many children to their destination when they are in dangerous situations. Most of those taken to school in taxis are children with disabilities. The committee chairman said she had received numerous complaints from parents who worried constantly about how their children were transported without safety seats and thus at risk of being hurt in accidents.
Asi Suzanna, head of the freight division of the Transport Ministry, said that every taxi driver should be required to hold a number of different-sized safety seats in the trunk and install them as needed when a child passenger needs to be taken. There are taxi stations that do this when informed in advance, but it is the responsibility of the parents to make sure there is a suitable seat and that their children don’t alight without it.
In a very rare case, a 27-year-old woman delivered her first baby, a healthy girl, after surgeons at Hadassah University Medical Center on Jerusalem’s Mount Scopus had operated on the fetus in the womb and saved its life. It was apparently the first such pregnancy in Israel. Twentyseven- year-old Mazal Kadosh had been pregnant with twins in one amniotic sac. Although in this case they are always identical twins and thus were supposed to be of the same sex, at the 20th week it was discovered that the fetuses were a male and female who had melded together in one pregnancy. Only in a handful of cases in the medical literature have they been separated. The twins shared a joint placenta and blood supply. In this case, the male fetus had a severe heart defect and had to be eliminated because it prevented the other from developing.
During the pregnancy, Dr. Dan Valsky wanted to know for sure if the blood supply was shared by the fetuses.
Tests showing the fetuses’ genes were different came out positive. Due to the coronary defect, every minute they were attached endangered the female fetus. Using a special tiny device, the fetuses were separated in the womb in the 24th week. The pregnancy continued normally, and she just gave birth by cesarean section.