Whether we are playing a team sport or just strolling through the park, we continually are aware of the positions of those around us--and where each is heading. Scientists have, in recent decades, pinpointed neurons called "place cells" in the brain that encode our location in the environment, but how our brains represent the positions of others has been a mystery However, research with bats reveals a subpopulation of neurons that encode the specific locations of other bats that are flying nearby
"Bats, like humans, are social animals; they are supreme navigators and they are very aware of other bats in their spatial environment," says Nachum Ulanovsky, professor in the Department of Neurobiology at the Weizmann Institute of Science. His research with Egyptian fruit bats focuses on place cells, which are found in a part of the brain called the hippocampus. These cells, which help humans and other mammals form the internal cognitive maps that we use to navigate our environment, garnered their discoverers a Nobel Prize in 2014.
More recent research suggests that the hippocampus also may play a role in social interaction. So, Ulanovsky and his group--including David Omer, Liora Las, and Shir Maimon--looked into how these two functions (place and social) might intersect in this part of the brain.
The team devised an experimental learning situation for the bats in its unique "bat lab," in which two bats--a "teacher" and a "student"--were paired. The student at first observed how the teacher flew towards one of the "fruit stands" placed in the lab and back to his perch. After about 13 seconds, on average, the student tracked the teacher's route to the food.
To uncover what was taking place within the bats' brains, each bat was equipped with a neural logger--a miniature wireless recording device-and tiny electrodes that enabled the researchers to record the activity of nearly 400 brain cells in the forward region of the hippocampus. The electrodes and recording device do not interfere with the bats' activities in any way
"The most challenging part of the experiments was to prevent the two bats from flying off together, as we needed one to stay put so we could differentiate the self- from the other-place cells," explains Ulanovsky. 'The trick was to identify the alpha males of the group and make them the teachers--this then made the students 'pay respect' and not fly out together with the teachers."
The results of these...