9631336 Touretzky In order to navigate successfully through the world, especially in the absence of visual input (e.g., in the dark), animals must maintain an accurate estimate of the direction in which they are facing. In rodents, the heading estimate is probably updated by a combination of vestibular cues from the inner ear, visual cues, and information about the animal's motor actions. This award supports the development of computer models of portions of the rodent brain involved in representing head direction, such as the anterior thalamic nuclei and the postsubiculum. Based on what is known about the tuning properties of head direction cells, the head direction system appears to exhibit a self- organizing activity pattern, called an attractor, that shifts as the animal's heading changes. Computer modeling can reveal how this attractor system operates. This research promises to yield new insights into how the nervous system organizes animal behavior and how information is represented in the mammalian brain.
