The visual response properties of neurons in the nucleus of the basal optic root of the northern saw-whet owl (Aegolius acadicus).
The nucleus of the basal optic root (nBOR) in birds is a component of the accessory optic system (AOS) which is involved in the analysis of visual flowfields normally resulting from self-motion. Using standard extracellular techniques, we recorded from 81 single-unit and multi-unit clusters in the nBOR of the northern saw-whet owl, Aegolius acadicus, an avian species that has a visual system with frontal emphasis. These cells responded best to large patterns of random dots moving either upward (52%), downward (31%) or nasal to temporal (N-T; contralateral visual field; 15%). Only 2 units (2%) preferred temporal to nasal motion. 'Up' units were found in the dorsal portion of the nucleus whereas 'Down' units were located more ventrally. The N-T units were found in both the lateral margin of the nucleus and ventral to the Down units in the lateral half of the nucleus. About half of the units tested (10/19) responded to stimulation of the ipsilateral as well as the contralateral eye. For all but one cell, the direction preference of both eyes was the same in visual space. When compared with previous studies of pigeons (Columba livia) and chickens (Gallus domesticus), these findings reveal that the nBOR in all three avian species have important similarities with respect to direction preference and functional compartmentalization. Furthermore, the high proportion of binocular neurons found in the nBOR of the saw-whet owl is similar to the condition generally reported in frontal eyed mammals and hence may reflect adaptation.
Wylie
D R
DR
Department of Physiology and Biophysics, New York University Medical Center, N.Y.
Shaver
S W
SW
Frost
B J
BJ
D000818:Animals; D001288:Attention / Q000502:physiology; D001717:Birds / Q000502:physiology*; D001931:Brain Mapping; D005074:Evoked Potentials, Visual / Q000502:physiology; D007699:Kinesthesis / Q000502:physiology*; D009039:Motion Perception / Q000502:physiology*; D009760:Nystagmus, Physiologic / Q000502:physiology; D009900:Optic Nerve / Q000502:physiology*; D009949:Orientation / Q000502:physiology*; D012160:Retina / Q000502:physiology; D012165:Retinal Ganglion Cells / Q000502:physiology; D015348:Vision, Binocular / Q000502:physiology; D014794:Visual Fields / Q000502:physiology; D014795:Visual Pathways / Q000502:physiology; D014796:Visual Perception / Q000502:physiology*