Retinotopic representation of the bifoveate eye of the kestrel (Falco spraverius) on the optic tectum.
Like many diurnal raptors, the American kestrel or sparrow hawk, Falco sparverius, possesses two foveae in each eye. In this study, we used fundus photography and reversed ophthalmoscopy to plot the projection of these foveae onto the visual field, together with other retinal landmarks such as the pecten and ora terminali. From such data, it was determined that the central monocular fovea (CMF) and temporal binocular fovea (TBF) were separated by 36 deg and that the kestrel has 58 deg of binocular overlap when the eyes are appropriately converged. Single-cell and multi-unit recordings were used to systematically explore the tectal surface and map receptive fields (RF) onto a hemispheric screen. A retinotopic map of the tectal surface was produced from such data and revealed an expanded representation for each fovea on the tectum and a systematic increase in RF size from fovea to periphery. The functional significance of this organization is discussed.
Frost
B J
BJ
Department of Psychology, Queen's University, Kingston, Ontario, Canada.
Wise
L Z
LZ
Morgan
B
B
Bird
D
D
D000818:Animals; D001717:Birds; D003867:Depth Perception; D005584:Fovea Centralis / Q000502:physiology*; D005654:Fundus Oculi; D009887:Ophthalmoscopy; D012160:Retina / Q000502:physiology*; D013477:Superior Colliculi / Q000502:physiology*; D015348:Vision, Binocular; D014794:Visual Fields; D014795:Visual Pathways / Q000502:physiology*; D014796:Visual Perception / Q000502:physiology