Looming-sensitive responses and receptive field organization of telencephalic neurons in the pigeon.
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.
Xiao
Qian
Q
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.
Li
Da-Peng
DP
Wang
Shu-Rong
SR
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*