Brain asymmetry improves processing of sensory information

February 6, 2014, University College London
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.

Explore further: The smoking gun: Fish brains and nicotine

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

Study of protein 'trafficker' provides insight into autism and other brain disorders

September 22, 2018
In the brain, as in business, connections are everything. To maintain cellular associates, the outer surface of a neuron, its membrane, must express particular proteins—proverbial hands that reach out and greet nearby cells. ...

Breast milk may be best for premature babies' brain development

September 21, 2018
Babies born before their due date show better brain development when fed breast milk rather than formula, a study has found.

Early warning sign of psychosis detected

September 21, 2018
Brains of people at risk of psychosis exhibit a pattern that can help predict whether they will go on to develop full-fledged schizophrenia, a new Yale-led study shows. The findings could help doctors begin early intervention ...

White matter repair and traumatic brain injury

September 20, 2018
Traumatic brain injury (TBI) is a leading cause of death and disability in the U.S., contributing to about 30 percent of all injury deaths, according to the CDC. TBI causes damage to both white and gray matter in the brain, ...

Genomic dark matter activity connects Parkinson's and psychiatric diseases

September 20, 2018
Dopamine neurons are located in the midbrain, but their tendril-like axons can branch far into the higher cortical areas, influencing how we move and how we feel. New genetic evidence has revealed that these specialized cells ...

Gut branches of vagus nerve essential components of brain's reward and motivation system

September 20, 2018
A novel gut-to-brain neural circuit establishes the vagus nerve as an essential component of the brain system that regulates reward and motivation, according to research conducted at the Icahn School of Medicine at Mount ...

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.