U. WASHINGTON (US) — Like humans, crows recognize faces and form associations with them—and to accomplish this, the two species’ brains appear to work in similar ways.
“The regions of the crow brain that work together are not unlike those that work together in mammals, including humans,” says John Marzluff, University of Washington professor of environmental and forest sciences. “These regions were suspected to work in birds but not documented until now.
“For example it appears that birds have a region of their brain that is analogous to the amygdala of mammals,” he says. “The amygdala is the region of the vertebrate brain where negative associations are stored as memories. Previous work primarily concerned its function in mammals while our work shows that a similar system is at work in birds.
“Our approach could be used in other animals—such as lizards and frogs—to see if the process is similar in those vertebrates as well.”
The “caring” and “threatening” masks both have neutral expressions, so the researchers could be sure the crows were remembering and responding to positive or negative associations. View larger. (Credit: Marzloff Lab/U. Washington)
Marzluff is the lead author of a paper published this week in the online edition of the Proceedings of the National Academy of Sciences.
Previous research on the neural circuitry of animal behavior has been conducted using well-studied, often domesticated, species like rats, chickens, zebra finches, pigeons, and rhesus macaques—but not wild animals like the 12 adult male crows in this study.
The crows were captured by investigators all wearing masks that the researchers referred to as “the threatening face.” The crows were never treated in a threatening way, but the fact they’d been captured created a negative association with the mask they saw.
Then, for the four weeks they were in captivity, they were fed by people wearing a mask different from the first—this one called “the caring face.” The masks were based on actual people’s faces and both bore neutral expressions so the associations made by the crows was based on their treatment.
Awake and active
In most previous neurological studies of animals, the work usually starts by sedating the animals, Marzluff says. Instead, the new approach involved injecting a glucose fluid commonly used in brain imaging into the bodies of fully alert crows that then went back to moving freely about their cages.
The fluid flooded to the parts of the crow brains that were most active as they were exposed for about 15 minutes to someone wearing either the threatening or caring mask.
Then the birds were sedated and scans made of their brains. All the birds were returned to the wild once all the work was completed.
“Our approach has wide applicability and potential to improve our understanding of the neural basis for animal behavior,” write Marzluff and co-authors Donna Cross, Robert Miyaoka, and Satoshi Minoshima, all faculty members with the radiology department. The department funded the preliminary work while the main project was conducted using money from the University’s Royalty Research Fund.
Most neurological studies to date in birds have concerned their songs—how their brain registers what they hear, how they learn and come up with songs of their own. This new approach enables researchers to study the visual system of birds and how the brain integrates visual sensation into behavioral action, Marzluff says.
Among other things the findings have implications for lowering the stress of captive animals, he says.
“By feeding and caring for birds in captivity their brain activity suggests that the birds view their keepers as valued social partners, rather than animals that must be feared. So, to keep captive animals happy we need to treat them well and do so consistently,” he says.
Intriguingly, Marzluff says the findings might also offer a way to reduce conflict between birds and endangered species on which they might be feeding. In the Mojave Desert, for instance, ravens prey on endangered desert tortoises. And on the West and East coasts, crows and ravens prey on threatened snowy plovers.
“Our studies suggest that we can train these birds to do the right thing,” Marzluff says. “By pairing a negative experience with eating a tortoise or a plover, the brain of the birds quickly learns the association. To reduce predation in a specific area we could train birds to avoid that area or that particular prey by catching them as they attempt to prey on the rare species.”
Collaborative work among neuroscientists and ecologists could be used to better understand the neural basis of cognition in widely diverse animals, says co-author Cross. For example, her suggestion to use the glucose technique prior to brain scans, so the crows could be fully awake, could be used for other animals.
A researchers wore the “caring mask” to feed the crows. (Credit: Jack DeLap/U of Washington)
Source: University of Washington