title: Computation of different optical variables of looming objects in pigeon nucleus rotundus neurons.
abstract: Three types of looming-selective neurons have been found in the nucleus rotundus of pigeons, each computing a different optical variable related to image expansion of objects approaching on a direct collision course with the bird. None of these neurons respond to simulated approach toward stationary objects. A detailed analysis of these neurons' firing pattern to approaching objects of different sizes and velocities shows that one group of neurons signals relative rate of expansion tau (tau), a second group signals absolute rate of expansion rho (rho), and a third group signals yet another optical variable eta (eta). The rho parameter is required for the computation of both tau and eta, whose respective ecological functions probably provide precise 'time-to-collision' information and 'early warning' detection for large approaching objects.
authors: Department of Psychology, Queen's University, Kingston, Ontario, Canada.
authors: H
authors: H
authors: Sun
authors: B J
authors: BJ
authors: Frost
mesh_terms: D000818:Animals; D001921:Brain / Q000166:cytology / Q000502:physiology*; D010856:Columbidae; D004924:Escape Reaction / Q000502:physiology*; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology*