How mantis shrimp make sense of the world

November 25, 2019

A study involving scientists at the University of Arizona and the University of Queensland provides new insight into how the small brains of mantis shrimp - fierce predators with keen vision that are among the fastest strikers in the animal kingdom - are able to make sense of a breathtaking amount of visual input.

The researchers examined the neuronal organization of mantis shrimp, which are among the top predatory animals of coral reefs and other shallow warm water environments.

The research team discovered a region of the mantis shrimp brain they called the reniform ("kidney-shaped") body. The discovery sheds new light on how the crustaceans may process and integrate visual information with other sensory input.

Mantis shrimp sport the most complex visual system of any living animal. They are unique in that they have a pair of eyes that move independently of each other, each with stereoscopic vision and possessing a band of photoreceptors that can distinguish up to 12 different wavelengths as well as linear and circular polarized light. Humans, by comparison, can only perceive three wavelengths - red, green and blue.

Therefore, mantis shrimp have much more spectral information entering their brains than humans do. Mantis shrimp seem to be able to process all of the different channels of information with the participation of the reniform body, a region of the animal's brain found in the eye stalks that support its two protruding eyes.

Researchers Hanne Thoen and Justin Marshall at Queensland Brain Institute at the University of Queensland in Brisbane, Australia, teamed up with Nicholas Strausfeld at the University of Arizona, as well as scientists from Lund University in Sweden and the University of Washington in the U.S. to gain a better understanding of how the reniform bodies connect to other parts of the mantis shrimp brain and gather clues to their functional roles.

Using a variety of imaging techniques, the team traced connections made by neurons in the reniform body and discovered that it contains a number of distinct, interacting subsections. One particular subunit is connected to a deep visual center called the lobula, which is structurally comparable to a simplified visual cortex.

"This arrangement may allow mantis shrimp to store quite high-level visual information," said Strausfeld, senior author of the paper that was published in the Journal of Comparative Neurology.

"Mantis shrimp most likely use these subsections of the reniform body to process different types of color information coming in and organize it in a way that makes sense to the rest of the brain," said lead author Thoen. "This would enable them to interpret a large amount of visual information very quickly."

One of the study's crucial findings was that neural connections link the reniform bodies to centers called mushroom bodies, iconic structures of arthropod brains that are required for olfactory learning and memory.

"The fact that we were now able to demonstrate that the reniform body is also connected to the mushroom body and provides information to it, suggests that olfactory processing may take place in the context of already established visual memories," said Strausfeld, Regents Professor of neuroscience and director of the Center for Insect Science at the University of Arizona.

The discovery of the reniform body, however, is not limited to mantis shrimp. It has been identified in other species as well, including shore crabs, shrimp and crayfish.

In 2016, an Argentinian group discovered that, in crabs, what are now known as reniform bodies act as secondary centers for learning and memory. According to Strausfeld, this suggests that the formation and storage of memories occurs in at least two different and discrete sites in the brain of the mantis shrimp and likely other members of malacostracans, the largest class of crustaceans. In addition to mantis shrimp, malacostracans include crabs, lobsters, crayfish, shrimp, krill and other less familiar species that together account for about 40,000 living species and a great diversity of body forms.

Reniform bodies have not been identified in insects and may be uniquely crustacean attributes, the researchers say. Alternatively, they might be homologous to a structure found in insect brains called the lateral horn, which sits between the optic lobes and the mushroom bodies. Strausfeld pointed out that fruit fly research done by other groups showed that the lateral horn is crucial in assigning values to learned olfactory information.

"The hunt is now on to determine if insects have a homologous center," he said. "If we are looking for homologs in other arthropods, the reniform body would be the obvious candidate."
-end-
The study was funded in part by the Asian Office of Aerospace Research and Development (12?4063), the Australian Research Council (FL140100197) and the National Science Foundation (11754798).

University of Arizona

Related Brain Articles from Brightsurf:

Glioblastoma nanomedicine crosses into brain in mice, eradicates recurring brain cancer
A new synthetic protein nanoparticle capable of slipping past the nearly impermeable blood-brain barrier in mice could deliver cancer-killing drugs directly to malignant brain tumors, new research from the University of Michigan shows.

Children with asymptomatic brain bleeds as newborns show normal brain development at age 2
A study by UNC researchers finds that neurodevelopmental scores and gray matter volumes at age two years did not differ between children who had MRI-confirmed asymptomatic subdural hemorrhages when they were neonates, compared to children with no history of subdural hemorrhage.

New model of human brain 'conversations' could inform research on brain disease, cognition
A team of Indiana University neuroscientists has built a new model of human brain networks that sheds light on how the brain functions.

Human brain size gene triggers bigger brain in monkeys
Dresden and Japanese researchers show that a human-specific gene causes a larger neocortex in the common marmoset, a non-human primate.

Unique insight into development of the human brain: Model of the early embryonic brain
Stem cell researchers from the University of Copenhagen have designed a model of an early embryonic brain.

An optical brain-to-brain interface supports information exchange for locomotion control
Chinese researchers established an optical BtBI that supports rapid information transmission for precise locomotion control, thus providing a proof-of-principle demonstration of fast BtBI for real-time behavioral control.

Transplanting human nerve cells into a mouse brain reveals how they wire into brain circuits
A team of researchers led by Pierre Vanderhaeghen and Vincent Bonin (VIB-KU Leuven, Université libre de Bruxelles and NERF) showed how human nerve cells can develop at their own pace, and form highly precise connections with the surrounding mouse brain cells.

Brain scans reveal how the human brain compensates when one hemisphere is removed
Researchers studying six adults who had one of their brain hemispheres removed during childhood to reduce epileptic seizures found that the remaining half of the brain formed unusually strong connections between different functional brain networks, which potentially help the body to function as if the brain were intact.

Alcohol byproduct contributes to brain chemistry changes in specific brain regions
Study of mouse models provides clear implications for new targets to treat alcohol use disorder and fetal alcohol syndrome.

Scientists predict the areas of the brain to stimulate transitions between different brain states
Using a computer model of the brain, Gustavo Deco, director of the Center for Brain and Cognition, and Josephine Cruzat, a member of his team, together with a group of international collaborators, have developed an innovative method published in Proceedings of the National Academy of Sciences on Sept.

Read More: Brain News and Brain Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.