Why does the human brain know which direction you’re facing, even when you’re not paying attention? A study published in the journal Nature Human Behaviour may have the answer. Researchers from the University of Birmingham and Ludwig Maximilian University of Munich have identified a pattern of brain activity that helps prevent us from getting lost, pinpointing the location of an internal neural compass that the human brain uses to orient itself in space and navigate through the environment.
Imagine you’re exploring a new city, trying to find your way back to your hotel. Even small errors in estimating where you are and which direction you’re heading in can be disastrous.
“Keeping track of the direction you are heading in is pretty important,” says first study author Dr. Benjamin J. Griffiths, from the Department of Psychology at the Ludwig Maximilian University of Munich. “Even small errors in estimating where you are and which direction you are heading in can be disastrous. We know that animals such as birds, rats and bats have neural circuitry that keeps them on track, but we know surprisingly little about how the human brain manages this out and about in the real world.”
One of the biggest challenges in studying how the brain navigates is that most technologies available require participants to remain as still as possible. To overcome this hurdle, the international team of researchers used mobile EEG (electroencephalography) devices and motion capture to record brain activity while participants were moving.
In the study, 52 healthy participants took part in a series of motion-tracking experiments. They wore EEG caps, which measure signals from the scalp, and moved their heads to orient themselves to cues on different computer monitors. In a separate study, researchers monitored signals from 10 participants who were already undergoing intracranial electrode monitoring for conditions such as epilepsy. This allowed them to record data directly from the hippocampus and neighboring regions, which are crucial for navigation and memory.
Isolating the Neural Compass
After accounting for “confounds” in the EEG recordings, such as muscle movement or the participant’s position within the environment, researchers were able to isolate a finely tuned directional signal. This signal could be detected just before physical changes in head direction among participants, suggesting that it represents the brain’s internal compass.
“Isolating these signals enables us to really focus on how the brain processes navigational information and how these signals work alongside other cues such as visual landmarks,” explains Dr. Griffiths. “Our approach has opened up new avenues for exploring these features, with implications for research into neurodegenerative diseases and even for improving navigational technologies in robotics and AI.”
The results of this study are comparable to neural codes identified in rodents and have implications for understanding diseases such as Parkinson’s and Alzheimer’s, where navigation and orientation are often impaired. By better understanding how the healthy brain navigates, researchers may be able to develop new diagnostic tools and treatments for these debilitating conditions.
The team’s work is not stopping with spatial navigation. In future studies, they plan to investigate how the brain navigates through time, to find out if similar neuronal activity is responsible for memory. This could lead to new insights into how we form and retrieve memories, and how these processes are affected by aging and disease.
