title: Looming-sensitive responses and receptive field organization of telencephalic neurons in the pigeon.
abstract: The tectofugal pathway in birds goes from the optic tectum to the telencephalic entopallium via the thalamic nucleus rotundus (nRt). This pathway may be homologous to the colliculo-pulvinar-cortical pathway in mammals. It is known that a population of rotundal neurons in the pigeon can signal impending collision of looming objects with the animal. Here we show by single-unit recording that there exist two groups of looming-sensitive neurons in the entopallium. A tau cell starts firing at a nearly constant time before collision whereas the response onset time of an eta cell is linearly related to the square root of the diameter/velocity ratio of looming objects. These cells are localized in the caudal entopallium. The receptive field (RF) of looming-sensitive cells was mapped on the screen plane but its inhibitory region could not suppress responses to looming objects. It appears that a population of telencephalic cells in pigeons responds to looming objects and their looming responses are not determined by the receptive field organization mapped on the screen plane.
authors.affiliation: Laboratory for Visual Information Processing, State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, PR China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Xiao
authors.forename: Da-Peng
authors.initials: DP
authors.lastname: Li
authors.forename: Shu-Rong
authors.initials: SR
authors.lastname: Wang
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001931:Brain Mapping; D002452:Cell Count / Q000379:methods; D010856:Columbidae / Q000502:physiology; D009039:Motion Perception / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000502:physiology*; D010364:Pattern Recognition, Visual / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D013687:Telencephalon / Q000166:cytology*; D014794:Visual Fields / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology*