Diverse synaptic mechanisms generate direction selectivity in the rabbit retina.
The synaptic conductance of the On-Off direction-selective ganglion cells was measured during visual stimulation to determine whether the direction selectivity is a property of the circuitry presynaptic to the ganglion cells or is generated by postsynaptic interaction of excitatory and inhibitory inputs. Three synaptic asymmetries were identified that contribute to the generation of direction-selective responses: (1) a presynaptic mechanism producing stronger excitation in the preferred direction, (2) a presynaptic mechanism producing stronger inhibition in the opposite direction, and (3) postsynaptic interaction of excitation with spatially offset inhibition. Although the on- and off-responses showed the same directional tuning, the off-response was generated by all three mechanisms, whereas the on-response was generated primarily by the two presynaptic mechanisms. The results indicate that, within a single neuron, different strategies are used within distinct dendritic arbors to accomplish the same neural computation.
John Curtin School of Medical Research and Centre for Visual Sciences, Australian National University, Canberra, 2601 ACT, Australia. taylorw@ohsu.edu
W Rowland
WR
Taylor
David I
DI
Vaney
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D066298:In Vitro Techniques; D009039:Motion Perception / Q000502:physiology*; D009431:Neural Conduction / Q000187:drug effects / Q000502:physiology; D009433:Neural Inhibition / Q000187:drug effects / Q000502:physiology; D018408:Patch-Clamp Techniques; D011817:Rabbits; D012160:Retina / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D012165:Retinal Ganglion Cells / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology*
D002712:Chlorides