Brain Surgery on Monarch Butterflies

By Karin Bolcshazy

Whaaat, you say….impossible. But it's true - scientists are performing brain surgery on monarch butterflies to study navigation during their long migrations.  How do they know where to go?  We already know that they use the sun's position to determine direction, but can they also use the earth's magnetic field?

The procedure involves inserting electrodes into the butterflies' brains to control the magnetic fields and track their brain activity.  This research aims to solve the mystery of how monarchs navigate thousands of miles from the U.S. and Canada to Mexico, especially during cloudy or rainy days when the sun is not visible. It's possible that they sense the Earth's magnetic field.  The electrodes are smaller than a human hair and attach to four neurons in the brain that are thought to control this magnetic sense.  The monarchs are then carefully placed into a flight simulator the size of a coffee urn, where researchers can control the magnetic fields inside as they fly.  The electrodes are connected to a computer tracking their brain activity. Spikes in brain activity might suggest that the butterfly is sensing the Earth's magnetic field.  But more research is needed.

How is it done?  Slips of tape hold the butterfly's black and orange wings open and pin its body under a microscope revealing a tiny, yellowish mass – the brain, smaller than a grain of rice - into which four electrodes are being inserted.  Then the monarch's head is carefully sealed with silicone to prevent the electrodes from shifting.  Following this delicate "operation", the butterfly is moved outdoors to a flight simulator where the butterfly is tethered and able to fly through a carefully controlled magnetic field.  If, and that's a big if, the butterfly has survived the procedure and the electrodes stay in place, the scientist can record the exact moment when its brain senses the kind of magnetic field that enables them to navigate such long distances.  It's a long trial and error process – electrons are implanted in 4 distinct neurons on the monarch's brain (monarchs have about 100 million neurons).  Looking at the bigger picture, this research theoretically holds the potential for developing human navigation systems that don't rely on satellites or GPS.  Somewhere in a brain smaller that a grain of rice might lie the answer to how living beings tap into an invisible field to journey across the planet.