Brainy courage of the rainbowfish

April 10, 2014
Brainy courage of the rainbowfish

The boldest black-lined rainbowfish are those that are born in the wild. Also more fearless are those that analyze information both sides of their brains. This is the conclusion of Australian researchers Culum Brown and Anne-Laurence Bibost from Macquarie University, in a study published in Springer's journal Behavioral Ecology and Sociobiology.

The preference to analyze and react to with either the left or of the brain is called cerebral lateralization, and is widespread among vertebrates. Lateralization is seen in the preference of humans or parrots to use one hand or claw over the other or to always turn to the same side when moving around objects.

The researchers first tested wild rainbowfish against captive rainbowfish. They then used a modified version of the mirror test to find out if a showed a lateral preference to view itself with either its left or right eye. Levels of boldness were tested by timing how long it took a fish to emerge from a safe hiding place.

Non-lateralized fish that did not analyze information in a specific brain hemisphere were significantly bolder than both left- and right-lateralized fish. This suggests that fear is heightened when primarily processed by a single hemisphere, making lateralized fish less bold. Previous studies have shown that complex tasks are more difficult to perform when information processing is shared between two . It therefore boils down to a question of speed. A non-lateralized fish in a potentially life-threatening situation must first draw information from both hemispheres, and compare and integrate it before it can make a decision. Strongly lateralized fish, on the other hand, can act more quickly because they only draw on information from a single hemisphere.

If non-lateralized fish process fear-related stimuli comparatively slowly or inefficiently, it may be that the moderating effect of fear is somewhat lessened in comparison to strongly lateralized fish. The researchers think this may result in a reduced level of fear generally, or perhaps the decision to explore is already made before the moderating effect of fear comes into play. Either scenario would adequately explain their observation that non-lateralized fish are bolder than lateralized fish.

The researchers were not surprised that wild fish were significantly bolder than captive-reared fish, as previous work they had done showed that populations that are hunted by predators were braver than those from low-predation areas.

"The similarities between personality and laterality are certainly intriguing and hint at a single underlying function or mechanism," says Brown. "We suggest that these aspects of personality traits are actually caused by variation in laterality."

Explore further: Symmetrical brains can be an advantage

More information: Brown, C. & Bibost, A-L. (2014). Laterality is linked to personality in the black-lined rainbowfish, Melanotaenia nigrans, Behavioral Ecology and Sociobiology, DOI: 10.1007/s00265-014-1712-0

Related Stories

Symmetrical brains can be an advantage

October 1, 2009

(PhysOrg.com) -- Many studies have found widespread asymmetry in the brains of different species, including humans, and most have assumed asymmetry is advantageous. A new paper, published in the Proceedings of the Royal Society ...

Fishy behaviour

October 4, 2011

A fish's personality may determine how it is captured. This association between personality difference and capture-technique could have significant evolutionary and ecological consequences for affected fish populations, as ...

Heritable variation discovered in trout behaviour

March 13, 2014

Populations of endangered salmonids are supported by releasing large quantities of hatchery-reared fish, but the fisheries' catches have continued to decrease. Earlier research has shown that certain behavioural traits explain ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

4 million years at Africa's salad bar

August 3, 2015

As grasses grew more common in Africa, most major mammal groups tried grazing on them at times during the past 4 million years, but some of the animals went extinct or switched back to browsing on trees and shrubs, according ...

A look at living cells down to individual molecules

August 3, 2015

EPFL scientists have been able to produce footage of the evolution of living cells at a nanoscale resolution by combining atomic force microscopy and an a super resolution optical imaging system that follows molecules that ...

New lizard named after Sir David Attenborough

August 3, 2015

A research team led by Dr Martin Whiting from the Department of Biological Sciences recently discovered a beautifully coloured new species of flat lizard, which they have named Platysaurus attenboroughi, after Sir David Attenborough.

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.