Special thanks to the Kavli JHU for funding my current work on how the bat hippocampus forms internal models of targets moving along naturalistic 2D trajectories.

Finally, leveraging the active nature of echolocation, we show that hippocampal object representations emerge only when bats actively track the target.

To distinguish between egocentric and allocentric coding, we conducted additional experiments in which the bat tracked the object from a different location in the room.

As the bats actively tracked the target, a population of ‘auditory object cells’ represented the moving target.

Using this metric, we trained bats to track a moving object in the dark via echolocation and recorded from hippocampal CA1 neurons, during which they increased their call rate as the target approached.

(Video credits - Mel Wohlgemuth)

Testing this idea requires a model system with an explicit metric of object tracking.

Echolocating bats adjust the rate and duration of their calls when tracking objects, providing a quantifiable measure of spatial attention to moving targets

Since echolocating bats use sound to explore complex 3D spaces, they present powerful model systems to answer how the brain builds spatial representations from non-visual inputs.