Brain asymmetry improves processing of sensory information

February 6, 2014
This is an image of the left and right sided habenular nuclei of larval zebrafish showing left/right structural asymmetries in the processes of neurons (pink) and their connections (blue). Fish that have symmetric brains show defects in processing information about sights and smells, according to the results of a new study into how asymmetry in the brain affects processing of sensory information. It's widely believed that the left and right sides of the brain have slightly different roles in cognition and in regulating behavior. However, scientists don't know whether these asymmetries actually matter for the efficient functioning of the brain. Now, a team from UCL and KU Leuven, Belgium has shown that, in zebrafish at least, loss of brain asymmetry can have significant consequences on sensory processing, raising the possibility that defects in the development of brain functions on either the left or right on the brain could cause cognitive dysfunction. The study is published today in Current Biology. Credit: Ana Faro/Tom Hawkins/Steve Wilson/UCL

Fish that have symmetric brains show defects in processing information about sights and smells, according to the results of a new study into how asymmetry in the brain affects processing of sensory information.

It's widely believed that the left and right sides of the have slightly different roles in cognition and in regulating behaviour. However, scientists don't know whether these asymmetries actually matter for the efficient functioning of the brain.

Now, a team from UCL and KU Leuven, Belgium has shown that, in zebrafish at least, loss of brain asymmetry can have significant consequences on sensory processing, raising the possibility that defects in the development of brain functions on either the left or right on the brain could cause . The study is published today in Current Biology.

Professor Steve Wilson, senior author of the study from the UCL Department of Cell & Developmental Biology, said: "We don't know whether asymmetries actually matter for the efficient functioning of the brain. For instance, if your brain was symmetric, would it work any less well than it normally does?

"This is potentially an important issue as brain-imaging studies in various neurological conditions have shown alterations in normally asymmetric patterns of neuronal activity." In their study the team used two-photon high resolution microscopy to image the activity of individual neurons in a part of the brain called the habenulae in larval zebrafish. This region of the brain shows asymmetries in many different vertebrates and is involved in mediating addiction, fear and reward pathways and probably influences numerous behaviour patterns.

In zebrafish habenulae most neurons responding to a light stimulus are on the left whereas most responding to odour are on the right. Using this knowledge to their advantage, scientists bred fish in which habenular asymmetry was reversed and fish with double-right and double-left sided habenulae. They then asked how the habenular neurons responded to visual or olfactory stimuli in these different conditions.

They found that if the direction of brain asymmetry was reversed, the functional properties of the habenular neurons were also reversed, whereas double-left and double-right sided brains almost completely lacked habenular responsiveness to odour or light respectively.

Dr Elena Dreosti, first author of the study, also from UCL Department of Cell & Developmental Biology, said: "These results show that loss of brain asymmetry can have significant consequences upon sensory processing and circuit function".

The research raises the possibility that defects in the establishment of brain lateralization could indeed be causative of cognitive or other symptoms of brain dysfunction.

More information: 'Left-Right Asymmetry Is Required for the Habenulae to Respond to Both Visual and Olfactory Stimuli' is published in the February 17, 2014 issue of Current Biology and online today.

Related Stories

The smoking gun: Fish brains and nicotine

December 9, 2013

In researching neural pathways, it helps to establish an analogous relationship between a region of the human brain and the brains of more-easily studied animal species. New work from a team led by Carnegie's Marnie Halpern ...

Do brain connections help shape religious beliefs?

January 27, 2014

Building on previous evidence showing that religious belief involves cognitive activity that can be mapped to specific brain regions, a new study has found that causal, directional connections between these brain networks ...

Recommended for you

Research grasps how the brain plans gripping motion

July 28, 2015

With the results of a new study, neuroscientists have a firmer grasp on the way the brain formulates commands for the hand to grip an object. The advance could lead to improvements in future brain-computer interfaces that ...

New research rethinks how we grab and hold onto objects

July 28, 2015

It's been a long day. You open your fridge and grab a nice, cold beer. A pretty simple task, right? Wrong. While you're debating between an IPA and a lager, your nervous system is calculating a complex problem: how hard to ...

It don't mean a thing if the brain ain't got that swing

July 27, 2015

Like Duke Ellington's 1931 jazz standard, the human brain improvises while its rhythm section keeps up a steady beat. But when it comes to taking on intellectually challenging tasks, groups of neurons tune in to one another ...

Static synapses on a moving structure: Mind the gap!

July 22, 2015

In biology, stability is important. From body temperature to blood pressure and sugar levels, our body ensures that these remain within reasonable limits and do not reach potentially damaging extremes. Neurons in the brain ...

Sleep makes our memories more accessible, study shows

July 27, 2015

Sleeping not only protects memories from being forgotten, it also makes them easier to access, according to new research from the University of Exeter and the Basque Centre for Cognition, Brain and Language. The findings ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.