Technological adaptation of brain activity recording for birds allows us, for the first time, to answer the eternal question: How do they know where to fly?
“We mammals and birds are separated by 300 million years, which is a long time in evolutionary terms, and therefore their brains are fundamentally different from ours,” explains Prof. Yoram Gutfreund of the Technion’s Faculty of Medicine. “We certainly have something to envy them. Birds know how to navigate thousands of kilometers, and they remember exactly where they hid their food the previous spring. We are looking for the neural basis of this internal sense of direction, in order to understand how the birds’ wonderful cognitive GPS works.”
In their previous study, Prof. Gutfreund and his team found that when a bird looks at a tree, for example, it is not only aware of its location in space in relation to the tree, but it also knows whether its head is facing north, south, east or west – in other words, it is aware of its global location. The combination of location knowledge and direction knowledge allows it to orient itself in space and correct its course if it happens to deviate from it. Since the bird knows the location of the target and its own location, as well as the absolute direction in which it is moving, it can be said that it has a “cognitive map” in its mind.
“We found that the bird’s brain has clear representations of its absolute position in space,” says Prof. Gutfreund. “This is very interesting, because information about absolute position in the world cannot come directly from sensory systems such as vision and hearing. So we wanted to look for which cells in the bird’s brain are responsible for this ability.” The biggest challenge, he explains, is “to record the behavior of individual neurons while the bird is moving freely and the devices are not disturbing it.” Since brain cell activity recording technologies were developed mainly for experiments on mice, adapting them to birds is a real engineering challenge. “And you have to guess where these cells might be,” adds Prof. Gutfreund, “because looking for cells in the brain is like looking for a needle in a haystack. The brain is a big place with lots of cells, and you can’t get an efficient recording of the activity in all of them.”
In Prof. Gutfreund's lab, quail, a domesticated and migratory bird, were raised and photographed in their daily lives. For example, food is brought into the room – and the quail obviously turns to look at it. All the while, the researchers recorded the quail's brain activity, in relation to absolute direction, relative direction, the speed of the quail's progress, and more.
“We found cells that tell us which absolute direction the bird is looking, and now I can tell you without seeing the bird at all – without seeing the camera footage, solely based on its brain activity – whether it is looking north, south, east or west.
They have a mental representation of global directions. Similar cells have previously been found in rodents and flies, but this is the first time they have been found in birds – a finding that strengthens the hypothesis that their special navigational ability is related to this sense of direction. After finding these cells, in the current study we are trying to understand how they are formed and work. What external signals are taken into account to calculate these directions? And in which areas of the brain do these signals pass – in visual or non-visual areas? Among other things, we intend to test what happens when the bird does not move in space but when we rotate the room. We are building a special room with a circular floor that can be rotated, and then we will see if the internal direction rotates along with the direction of the head.”
More of the topic in Hayadan:
