Yale-NUS professor's discovery of alarm response in medaka fish furthers analysis of fear

November 29, 2016

Singapore, 29 November 2016 - Yale-NUS Assistant Professor of Science Dr Ajay Mathuru has discovered that the medaka fish has an 'alarm response' to a type of semiochemical (message-bearing chemicals that carry information from one animal to another) released due to physical injuries sustained by another member of its kind. Since the 1970s, many scientists had considered this type of alarm behaviour to be unique to fishes of the superorder Ostariophysi. The medaka fish, a member of the Beloniformes order, is one of the few laboratory-friendly fish outside of the Ostariophysi superorder to similarly have a response to this type of semiochemical. With this discovery, it is now possible to perform non-invasive, comparative neural circuit analysis against the zebrafish, the species of the Ostariophysi superorder most commonly used in laboratories. Dr Mathuru's research was published on 8 November 2016 in Scientific Reports, a leading international scientific journal.

Considered an anti-predator mechanism, this semiochemical - Schreckstoff - triggers fear in fish by warning it of a nearby danger. Unlike humans, fish do not wait for visual confirmation of predators, but use their keen sense of smell to detect them. Dr Mathuru has found that while the medaka fish also has an 'alarm response', it reacts in a different way from the zebrafish - by playing dead. Since both species of fish are laboratory-friendly to raise and possess characteristics such as a translucent skin and skull when young, researchers are able to study the activity of neurons in their brains by non-invasive methods of imaging and compare their neural responses. Prior to this discovery, scientists were unable to use non-invasive methods to study fishes outside of the superorder Ostariophysi that exhibited an alarm response. Comparing the two types of fish that have a similar but distinctive alarm response will lend greater insight into how the brain processes information to generate behaviours when danger is felt.

Discussing the significance of the study, Dr Mathuru said, "It will be highly informative to look into the biochemistry of alarm cues and neural circuits operating in this way, in two species that shared a common ancestor approximately 110-160 million years ago. It will allow us to delve further into understanding how neural machinery orchestrates species-specific behaviours. It will also reveal if such a behaviour originated once in the course of evolution, or multiple times."

The discovery also has implications for improving our understanding of fear and panic in other animals, including humans. While the triggers for fear may be different for humans, the organisation of the fear circuitry could be similar. A greater understanding of such neural circuits may allow scientists to have a better understanding of uncontrolled fear in humans, such as those seen when panic disorders happen.
Dr Mathuru teaches Scientific Inquiry, and Neurobiology and Behaviour at Yale-NUS College. He also holds a joint appointment as Principal Investigator at the Institute of Molecular and Cell Biology (IMCB) of the Agency for Science, Technology and Research (A*STAR).

Yale-NUS College

Related Fear Articles from Brightsurf:

How does the brain process fear?
CSHL Professor Bo Li's team explores the brain circuits that underlie fear.

The overlap between fear and anxiety brain circuits
Fear and anxiety reflect overlapping brain circuits, according to research recently published in JNeurosci.

Fear of missing out impacts people of all ages
The social anxiety that other people are having fun without you, also known as FoMO, is more associated with loneliness, low self-esteem and low self-compassion than with age, according to a recent study led by Washington State University psychology professor Chris Barry.

How fear transforms into anxiety
University of New Mexico researchers identify for the first time the brain-wide neural correlates of the transition from fear to anxiety.

How associative fear memory is formed in the brain
Using a mouse model, a pair of UC Riverside researchers demonstrated the formation of fear memory involves the strengthening of neural pathways between two brain areas: the hippocampus, which responds to a particular context and encodes it, and the amygdala, which triggers defensive behavior, including fear responses.

What makes fear decrease
In uncanny situations, the mere presence of an unknown person can have a calming effect.

With these neurons, extinguishing fear is its own reward
The same neurons responsible for encoding reward also form new memories to suppress fearful ones, according to new research by scientists at The Picower Institute for Learning and Memory at MIT.

Having to defend one's sexuality increases fear of childbirth
In order to help people with fear of childbirth, there must be trust between the patient and the healthcare staff.

Fear of hospitalization keeps men from talking about suicide
Fear of psychiatric hospitalization is one of the primary reasons that older men -- an age and gender group at high risk for suicide -- don't talk about suicide with their physicians.

Brain activity predicts fear of pain
Researchers applied a machine learning technique that could potentially translate patterns of activity in fear-processing brain regions into scores on questionnaires used to assess a patient's fear of pain.

Read More: Fear News and Fear 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.