Study shows how brain cells shape temperature preferences

While the wooly musk ox may like it cold, fruit flies definitely do not. They like it hot, or at least warm. In fact, their preferred optimum temperature is very similar to that of humans—76 degrees F.

Scientists have known that a type of brain cell circuit helps regulate a variety of innate and learned behavior in animals, including their preferences. What has been a mystery is whether or not this behavior stems from a specific set of neurons (brain cells) or overlapping sets.

Now, a new study from The Scripps Research Institute (TSRI) shows that a complex set of overlapping works in concert to drive temperature preferences in the fruit fly Drosophila by affecting a single target, a heavy bundle of neurons within the fly brain known as the mushroom body. These nerve bundles, which get their name from their bulbous shape, play critical roles in learning and memory.

The study, published in the January 30, 2013 edition of the Journal of Neuroscience, shows that dopaminergic circuits— that synthesize dopamine, a common neurotransmitter—within the mushroom body do not encode a single signal, but rather perform a more complex computation of environmental conditions.

"We found that dopamine neurons process multiple inputs to generate multiple outputs—the same set of nerves process sensory information and reward-avoidance learning," said TSRI Assistant Professor Seth Tomchik. "This discovery helps lay the groundwork to better understand how information is processed in the brain. A similar set of neurons is involved in behavior preferences in humans—from basic rewards to more complex ."

Using imaging techniques that allow scientists to visualize in real time, the study illuminated the response of dopaminergic neurons to changes in temperature. The behavioral roles were then examined by silencing various subsets of these neurons. Flies were tested using a plate; the flies moved from one place to another to express their temperature preferences.

As it turns out, genetic silencing of dopaminergic neurons innervating the mushroom body substantially reduces cold avoidance behavior. "If you give the fly a choice, it will pick San Diego weather every time," Tomchik said, "but if you shut down those nerves, they suddenly don't mind being in Minnesota."

The study also showed dopaminergic neurons respond to cooling with sudden a burst of activity at the onset of a drop in temperature, before settling down to a lower steady-state level. This initial burst of dopamine could function to increase neuronal plasticity—the ability to adapt—during periods of environmental change when the organism needs to acquire new associative memories or update previous associations with temperature changes.

More information: "Dopaminergic Neurons Encode a Distributed, Asymmetric Representation of Temperature in Drosophila," Journal of Neuroscience, 2013.

Related Stories

Scientists identify mechanism of long-term memory

Apr 13, 2011

Using advanced imaging technology, scientists from the Florida campus of The Scripps Research Institute have identified a change in chemical influx into a specific set of neurons in the common fruit fly that is fundamental ...

Recommended for you

What happens in our brain when we unlock a door?

2 hours ago

People who are unable to button up their jacket or who find it difficult to insert a key in lock suffer from a condition known as apraxia. This means that their motor skills have been impaired – as a result ...

Sport can help multiple sclerosis patients

6 hours ago

A study developed at the Miguel Hernández University of Elche (Spain) has preliminarily concluded that people with multiple sclerosis may reduce perceived fatigue and increase mobility through a series of ...

Obama's BRAIN initiative gets more than $300 million

10 hours ago

President Barack Obama's initiative to study the brain and improve treatment of conditions like Alzheimer's and autism was given a boost Tuesday with the announcement of more than $300 million in funds.

User comments