Gamma oscillations coordinate food seeking

February 2, 2017
Credit: Claudia Knorr, FMP.

Food seeking is a crucial survival instinct. However, until recently, little was known about how the brain regulates this behavior. Scientists at the Leibniz-Institut für Molekulare Pharmakologie (FMP) and NeuroCure Cluster of Excellence in Berlin discovered a neuronal circuit which regulates the hypothalamus and activates food seeking in mice. Surprisingly, this neural mechanism appeared to utilize gamma oscillations, and does not depend on hunger. Optogenetics techniques shed light on the behavioral function of this circuit. The findings allow for better understanding of the mechanisms of feeding behavior, and could lead to development of innovative therapies to treat eating disorders. These results have been published in the scientific journal Nature.

It is pretty normal that thoughts often revolve around food, even when you are not hungry. Food-seeking behavior, an instinct crucial for survival of our ancestors during hunting and gathering, leads us in the 21st century to a fridge or the supermarket. This behavior fascinates scientists as well, as impairments in this drive can be linked with eating disorders like anorexia nervosa. To understand how this behavior is organized, scientists study its neuronal mechanisms.

Gamma oscillations organize communication in hypothalamus

Gamma oscillations, occurring at a rate of 30 to 90 cycles per second, are waves of neural activity known to support major cognitive functions, including memory, attention and cognitive flexibility. Until recently, it was not known whether and how these processes regulate vital behaviours including food-seeking. A team of researchers led by Tatiana Korotkova and Alexey Ponomarenko at the FMP Institute/ NeuroCure Cluster of Excellence in Berlin found that the brain features a mechanism that directly informs the hypothalamus about cognitive processing using gamma oscillations as a common language.

"Together with scientists in the U.S. and the U.K., we characterized this pathway at multiple levels, from anatomical connections to excitability of individual cells," says Tatiana Korotkova, describing their study published in the scientific journal Nature.

Optogenetics helped to shed light on neuronal mechanisms

To study this , researchers used optogenetics, a novel method that allows activation of specific connections in the brain using light. Researchers found gamma oscillations in the lateral hypothalamus and its major gateway, the lateral septum, and noted that this brain rhythm increases as a mouse seeks food. "It was impressive to see that gamma oscillations had such a pronounced effect in LH, which was previously thought to respond mainly to chemical/hormonal signaling," explains Ph.D. student Marta Carus. In the study, replay of these oscillations in the brain, using optogenetics, led to food seeking.

Food seeking independent of food consumption

Remarkably, during gamma synchronization of this brain circuit, animals checked the food location even if they were not hungry. However, they did not consume more food than usual. Activation of this pathway also assisted in cognitively demanding situations, when the mouse had to find food using previous experience. The prefrontal cortex, a brain region that coordinates goal-directed behavior, was important for this. "Finding suitable food in the wild is tricky and time-consuming," says Tatiana Korotkova. "It's probably too late to start searching for food when an animal is already hungry, if it has no idea about what nutritional resources are available where. This circuit possibly makes us pay specific attention to food sources, such as spotting restaurants when exploring a new town, or regularly checking the fridge contents in our own kitchen."

Researchers further managed to translate parts of the code used during gamma oscillations for communication in this neural pathway. Activity of many neurons in the depends on presence of food: while some neurons are active close to food, others are preferentially active distantly from the food location. Researchers found that during feeding-related cells are activated separately from feeding-unrelated cells with high temporal precision. "Preferential and selective control of feeding-related cells by rhythmic inputs to hypothalamus demonstrates a beautiful interaction of structure and function in the brain" says Alexey Ponomarenko. "Here we see how fast synchronization, combined with a precise information transfer between regions and cells types, drives behaviors crucial for survival."

A disconnect between -seeking behavior and metabolic needs is a symptom of many eating disorders, ranging from anorexia to obesity. There is still a long way to go for the development of effective medications, however, understanding of neuronal mechanisms which regulate feeding may lead to development of innovative therapies.

Explore further: Theta oscillations coordinate navigation and movement

More information: Marta Carus-Cadavieco et al. Gamma oscillations organize top-down signalling to hypothalamus and enable food seeking, Nature (2017). DOI: 10.1038/nature21066

Related Stories

Theta oscillations coordinate navigation and movement

October 13, 2015
Using light pulses, Berlin scientists have recently managed to control theta oscillations in mouse brain. They discovered that these brain waves coordinate movement - enabling signaling between distant brain regions – a ...

Researchers discover brain circuit that controls compulsive overeating and sugar addiction

January 29, 2015
Compulsive overeating and sugar addiction are major threats to human health, but potential treatments face the risk of impairing normal feeding behaviors that are crucial for survival. A study published January 29th in the ...

Brains of those with anorexia and bulimia can override urge to eat

November 7, 2016
Scientists at the University of Colorado Anschutz Medical Campus have discovered the neurological reasons why those with anorexia and bulimia nervosa are able to override the urge to eat.

Scientists uncover mechanism that controls feeding behavior in mice

November 9, 2016
A team of scientists has discovered a mechanism that controls feeding behavior in mice by regulating the electrical activity of a few thousand brain cells. The researchers, from Baylor College of Medicine, South China Agricultural ...

New insights into brain circuit for hunger responses during starvation

January 26, 2017
Researchers uncover mechanism by which hypothalamic neural signaling drives hunger responses to survive starvation.

Researchers image effects of hunger on the brain's response to food cues

September 14, 2016
Our brain pays more attention to food when we are hungry than when we are sated. Now a team of scientists at Beth Israel Deaconess Medical Center has shed light on how the needs of the body affect the way the brain processes ...

Recommended for you

Researchers create tool to measure, control protein aggregation

October 22, 2017
A common thread ties seemingly unlinked disorders like Alzheimer's disease and type II diabetes together. This thread is known as protein aggregation and happens when proteins clump together. These complexes are a hallmark ...

Want to control your dreams? Here's how

October 19, 2017
New research at the University of Adelaide has found that a specific combination of techniques will increase people's chances of having lucid dreams, in which the dreamer is aware they're dreaming while it's still happening ...

Researchers find shifting relationship between flexibility, modularity in the brain

October 19, 2017
A new study by Rice University researchers takes a step toward what they see as key to the advance of neuroscience: a better understanding of the relationship between the brain's flexibility and its modularity.

Brain training can improve our understanding of speech in noisy places

October 19, 2017
For many people with hearing challenges, trying to follow a conversation in a crowded restaurant or other noisy venue is a major struggle, even with hearing aids. Now researchers reporting in Current Biology on October 19th ...

Investigating the most common genetic contributor to Parkinson's disease

October 19, 2017
LRRK2 gene mutations are the most common genetic cause of Parkinson's disease (PD), but the normal physiological role of this gene in the brain remains unclear. In a paper published in Neuron, Brigham and Women's Hospital ...

New procedure enables cultivation of human brain sections in the petri dish

October 19, 2017
Researchers at the University of Tübingen have become the first to keep human brain tissue alive outside the body for several weeks. The researchers, headed by Dr. Niklas Schwarz, Dr. Henner Koch and Dr. Thomas Wuttke at ...

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.