Navigation Links
Game of two halves leads to brain asymmetry

A tug-of-war between the two sides of the brain causes it to become asymmetrical, according to research published today in the journal Neuron. Asymmetry in the brain is thought to be important to enable the two hemispheres to specialise and operate more efficiently.

Left-right asymmetry is present in the brains of most animals and is first evident at the time of early brain development. However, until now, scientists did not know the mechanisms that bring it about. Now, in a study funded primarily by the Wellcome Trust, researchers have shown that a competition between the two sides causes this asymmetry.

By studying brain development in zebrafish, PhD student Jenny Regan and her colleagues in Professor Stephen Wilson's team at UCL (University College London) have shown that a protein known as Fgf8 acts as a magnet to attract nerve cells to one side of the brain. .

"Fgf8 is found in both sides of the brain, leading to a 'tug-of-war' competition between the two sides to attract the migrating group of nerve cells," says Dr Regan. "This isn't a fair fight, however Fgf8 on the left-hand side has an ally to help it win the battle."

A second protein, known as Nodal, is present only on the left and teams up with Fgf8 to attract the group of nerve cells, triggering a cascade of events that lead to asymmetric development of the brain, with neurons on the left making different connections to those on the right. The combined action of Fgf8 and Nodal ensures that when the asymmetry develops, it is usually in the same direction this helps to explain why there is consistent handedness between individuals. Nodal is known to also play a role in other areas of the body where asymmetry occurs, such as the heart and positioning of internal organs.

If Nodal is inhibited, the competition is fairer and the group of nerve cells has an equal probability of migrating to the right or left side, but a bias in the direction of migration can be restored by adding extra Fgf8 to one side of the brain.

"Brain asymmetry is essential for proper brain function," explains Professor Wilson. "It allows the two sides of the brain to become specialised, increasing its processing capacity and avoiding situations of conflict where both sides of the brain try to take charge.

"For example, faced with a predator, an animal would not want both sides of the brain to try to drive the escape as this might lead to conflict over which direction to turn. Instead, the animal might keep watch more with one eye (and consequently one half of the brain) and so each side of the brain might be dominant for particular activities."

Previous studies have shown that rearing chickens in the dark makes their brains less asymmetric. The chicks can still peck for food and watch out for predators, but only if doing one of these tasks at a time. When they try to do both, they are less efficient than fully asymmetric animals in which one eye specialises for one task and the other eye for the other task.

In humans, people with schizophrenia have disrupted brain asymmetries but as yet, it is not clear if there is a causal link between the asymmetry and schizophrenia.

"The direction and handedness that brain asymmetry takes is not critical for survival, but the strong bias towards one direction may be to ensure that all members of a population have consistent behaviours," adds Professor Wilson. "This may be very important for social animals, such as humans and schooling fish."


Contact: Craig Brierley
Wellcome Trust

Related biology news :

1. Study of placenta unexpectedly leads to cancer gene
2. Mayo Clinic research on tamoxifen leads to recommendation for CYP2D6 gene test
3. Personalized medicine: Innovative online journal leads the way
4. TECNALIA leads five projects within the VII Framework Program
5. Exposing chicks to maternal stress leads to long-term reproductive success
6. How neuronal activity leads to Alzheimers protein cleavage
7. FSU researchers discovery leads to $1.5 million grant, potential new treatment of liver fibrosis
8. Childrens national co-leads nationwide study of landmark sickle cell treatment
9. USC researchers identify alternate pathway that leads to palate development
10. Small research at MSU leads to advances in energy, electronics
11. 1 missing gene leads to fruitless mating rituals
Post Your Comments:
(Date:5/9/2016)... May 9, 2016 Elevay is ... to expanding freedom for high net worth professionals seeking ... today,s globally connected world, there is still no substitute ... ever duplicate sealing your deal with a firm handshake. ... by taking advantage of citizenship via investment programs like ...
(Date:4/26/2016)... DUBLIN , April 27, 2016 ... of the  "Global Multi-modal Biometrics Market 2016-2020"  report ... ) , The analysts forecast ... a CAGR of 15.49% during the period 2016-2020.  ... a number of sectors such as the healthcare, ...
(Date:4/13/2016)... 13, 2016  IMPOWER physicians supporting Medicaid patients in ... new clinical standard in telehealth thanks to a new ... higi platform, IMPOWER patients can routinely track key health ... mass index, and, when they opt in, share them ... to a local retail location at no cost. By ...
Breaking Biology News(10 mins):
(Date:6/27/2016)... ... June 27, 2016 , ... Rolf K. ... the faculty of the University of North Carolina Kenan-Flagler Business School ... entrepreneurship at UNC Kenan-Flagler, with a focus on the school’s international efforts, leading ...
(Date:6/24/2016)... 2016 Epic Sciences unveiled a liquid ... to PARP inhibitors by targeting homologous recombination deficiency ... new test has already been incorporated into numerous ... types. Over 230 clinical trials are ... including PARP, ATM, ATR, DNA-PK and WEE-1. Drugs ...
(Date:6/23/2016)... ... June 23, 2016 , ... UAS LifeSciences, one of ... their brand, UP4™ Probiotics, into Target stores nationwide. The company, which has been ... Target to its list of well-respected retailers. This list includes such fine stores ...
(Date:6/23/2016)... , June 23, 2016 Houston Methodist ... the Cy-Fair Sports Association to serve as their ... agreement, Houston Methodist Willowbrook will provide sponsorship support, ... connectivity with association coaches, volunteers, athletes and families. ... the Cy-Fair Sports Association and to bring Houston ...
Breaking Biology Technology: