Spatial Mapping in Perpetual Darkness: EvoDevo of Behavior in Astyanax mexicanus Cavefish

Spatial maps of the environment are generated and stored in our memory via neural encoding of position through multisensory perceptual learning. Animals acquire the information necessary to build these maps by walking, flying, or swimming through their environments to learn the positions of landmarks or cues, and retrieve these orientation memories when necessary. Troglobites live in underground caves in perpetual darkness; thus, these animals differ greatly from visually guided animals in the way they learn and build spatial maps. How, in the absence of vision, are other sensory systems able to compensate and integrate to provide the motor system with the coordinates of landmarks upon which to base navigation? The cavefish morphotype of Astyanax mexicanus is a troglobite that is completely blind due to retinal degradation early in its development; however, this morphotype has evolved—most likely via sensory substitution—the ability to navigate its cave environments very successfully. If we can understand how spatial maps are formed in Astyanax cavefish, we may be able to extrapolate such knowledge to understand how blind humans acquire navigational skills in the absence of vision.