image: Photo of an Egyptian fruit bat. Sarel et al. report on a new functional class of hippocampal neurons in bats, which encode the direction and distance to spatial goals - suggesting a novel neural mechanism for vector-based goal-directed navigation. This material relates to a paper that appeared in the Jan. 13, 2017, issue of Science, published by AAAS. The paper, by A. Sarel at Weizmann Institute of Science in Rehovot, Israel, and colleagues was titled, "Vectorial representation of spatial goals in the hippocampus of bats." view more
Credit: Steve Gettle
In bats, researchers have identified a subpopulation of neurons that represent navigational goals, a new study reports. The results provide valuable insights into how bats fly from A to B. To date, much research has shed light on the neural representation of an animal's own location and orientation, yet how spatial goals are encoded in the brain remains unclear. To gain a better understanding, Ayelet Sarel and colleagues trained Egyptian fruit bats to fly in complex patterns and land at a specific site, defined as the goal, where the bats could eat and rest. While the bats completed this task, a wireless electrophysiology device recorded individual neural activity in their hippocampus. About 19% of neurons recorded were found to act as "tuners," which varied in activity based on the angled directionality of a bat's flight path toward its goal. The authors note, however, that during real-life navigation the goal could be invisible to the animal, meaning that goal-directed navigation requires memory. Thus they conducted a second experiment where they masked the goal with an opaque curtain that blocked vision, echolocation, and olfaction. A substantial fraction of cells (43 of 158, or 27%) exhibited significant directional tuning to the hidden goal, suggesting that these goal-directed neurons also capture memory. When the goal was shifted in position, a portion of goal-directed tuning neurons changed, suggesting that some neurons are goal-specific. In a final experiment, a subset of neurons responsible for calculating distance towards the goal was identified. Most of these goal-distance cells fired maximally at short path distances of between 0 and 2 meters as the bat approached the goal.
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Journal
Science