On a Deserted Island, Science Unveils the Inner Workings of Bats’ Brain Compass
An Unprecedented Experiment on a Remote Island
Forty kilometers off the coast of Tanzania, in the Indian Ocean, stands Latham Island, a small strip of rock barely the size of seven soccer fields, uninhabited and isolated from the world. There, a group of scientists achieved something groundbreaking: recording the neuronal activity of mammals in the wild.
The study, published in Science, used microdevices implanted in fruit bats to analyze how their brains process spatial orientation. The results revealed that their “internal compass” works on a global scale and remains stable without depending on moonlight or stars.
The Quest for a Natural Laboratory
Neuroscientist Nachum Ulanovsky had been trying for years to study animal navigation outside the lab. “We needed an isolated environment, without tall trees and small enough to recapture the bats,” he explained. After a long search on Google Earth, he found the perfect island.
In February 2023, the team settled on the coast of Tanzania, set up a laboratory in a veterinary institute, and equipped six bats with devices capable of measuring brain activity and GPS position during flight.
Once on the island, the group faced extreme conditions: the passage of Cyclone Freddy, the longest ever recorded, delayed the first phase of the experiment. Only when the weather stabilized could they release the bats.
The Brain Compass: Neurons that Point North
During the study, researchers recorded the activity of over 400 neurons associated with orientation. Every time a bat turned its head in a specific direction—such as north—a specific set of cells was activated.
The most surprising finding was that these neurons maintained their directional reference constant across the entire island. “The compass is global and uniform: north is always north,” Ulanovsky pointed out. “Neither speed, altitude, nor landscape alter that reference.”
Learning and Spatial Memory
During the first nights, the bats showed disoriented flight patterns, but after several days, the patterns became more consistent. Scientists believe that the bats gradually learn the visual reference points of the environment, rather than relying on the Earth’s magnetic field.
To check whether the bats oriented themselves with the Sun, Moon, or stars, the scientists compared brain activity before and after lunar rise. The result was clear: the compass remained stable even with a cloudy sky.
From Bats to the Human Brain
Head orientation cells are an evolutionary mechanism present in many species, from insects to mammals. Studying them helps understand how brains build internal maps of space, knowledge that could aid in diagnosing conditions like Alzheimer’s.
The Future of Neuroscience in Nature
This expedition marks a turning point in field neuroscience. Thanks to technological miniaturization and interdisciplinary work, scientists demonstrated that studying the mind in the wild is now possible.
