RatCAP: mini wearable brain scanner links neurochemisty with behavior

A PET scanner that fits on rats while they're awake and moving provides real-time views into rodent (and ultimately human) behavior and brain function.
Written by Janet Fang, Contributor

A new portable brain scanner for rats can, for the first time, show how brain activity influences behavior. And it's ready to use.

Positron emission tomography (PET) imaging helps researchers look into brain activity – by measuring flashes of light to reveal blood flow. Now, scientists have created a PET scanner small enough for rats to wear.

Because it fits on rats while they're awake and moving around, the new tech assesses brain function and behavior at the same time – allowing a glimpse of all the info lost when looking at behavior and neurochemistry separately.

"It means we can watch how the animals behave and observe their brain chemistry at the same time," says study author David Schlyer of Brookhaven National Laboratory (BNL).

And as they say, this can eventually help researchers better understand functions in the human brain.

PET scans use small injections of radiopharmaceuticals to map metabolism of chemicals in real time. In addition to brain activity and blood flow, it helps examine organ function, uncover drug addiction or depression, diagnose cancer early, and research neurological conditions from Alzheimer's to epilepsy.

In humans, it’s pretty straightforward to use. Just lie down and relax. But rats don't really stay still inside an imaging scanner without being restrained, paralyzed, or anesthetized – ruling out many types of studies.

The team engineered a mini PET scan – known as RatCAP for Rat Conscious Animal PET (pictured). It’s about 38mm in diameter and weighs 250g. Most importantly, it allows neuroscientists to study molecular processes that occur in the brain during consciousness.

"It's a methodological issue," says study author Paul Vaska of BNL. "If you start to make assumptions that what you're seeing under anesthesia is what you'll see awake, you may make a mistake in your interpretation."

Other techniques to simultaneously track brain function and behavior, such as inserting a probe into brain tissue, are limited to small regions of the brain. The RatCAP, by contrast, looks globally across the brain.

For their inaugural test, the team looked at the neurotransmitter dopamine, comparing levels in anesthetized rats using conventional PET with awake rats using RatCAP:

  • Unexpectedly, dopamine levels in the awake rats were lower.
  • Dopamine levels are strongly linked with behavioral activity – like head turns and body motion.
  • Changes can be monitored on a minute-to-minute basis. (Current PET studies tend to average 30 to 60 minutes.)

“We can study changes in dopamine connected to drug abuse,” says first author Daniela Schulz of BNL, “but also the effect of change in other psychiatric disorders where proteins in the brain are important, like schizophrenia, attention deficit hyperactivity disorder and depression.”

The team hopes to develop wearable scanners for people and monkeys to move around and engage in activities while their brains are being scanned. According to Schlyer, "it would be something like a football helmet."

The study was published in Nature Methods this week.

Images: Brookhaven National Laboratory

This post was originally published on Smartplanet.com

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