In animals, the brain is divided into two hemispheres. In humans, the left hemisphere stores verbal information while the right hemisphere stores visuals information. However, even bugs and other invertebrates split information between the hemispheres of their brains. Bees, for example, will often store long-term memories of things they have smelled through their left antennae and short-term memories of scents they detect through the right antenna.
Researchers from the University of Sussex in England wanted to see if wood ants could lateralize their visual memories in a similar way. They collected several hundred ants from three colonies and showed them a blue piece of cardboard. Then a sugar solution was placed on either the ants’ left antenna, right antenna, both antennae, or neither antenna before the ant were allowed to drink the sugar water. The researchers then recorded whether ants would extend their mouths when presented with the blue cardboard in anticipation of the sugar water when showed the blue signal in future trials.
At first, the ants generally did not associate the blue cardboard with sugar water, but after 10 trials, between 20 and 30% of ants who had experienced sucrose being placed on one antenna immediately after seeing the blue color extended their mouths. About 50% of ants in the “both-antennae” group did. When the ants were re-exposed after either 10 minutes or 1 hour, the ants who had been touched on the right antenna or both antennae were much more likely than the left or no-antenna ants to extend their mouths, indicating that the right antenna might be associated with short-term memory. However, half of the ants from all of the experimental groups that were tested at 1 hour were tested again 24 hours after their initial training. This time, the ants who were touched on the left antenna associated the blue color with food much more than the ants who were touched on the right antenna.
From these results the researchers concluded that, when it comes to visual memories, these wood ants use their right antenna for short term memory and their left for long term memory. The researchers suggest that storing long and short term memories in different brain hemispheres may help ants save space and energy in their small brains. This research could be generalized to further explore the how many small seemingly simple animals like insects store information and navigate their worlds.
Managing Correspondent: Emily Kerr
Original Scientific Article: Lateralization of short- and long-term visual memories in an insect
Image Credit: Pawel Bieniewski