Signal shaping by voltage-gated currents in retinal ganglion cells.
The role of voltage-gated currents in information processing by retinal ganglion cells was assessed by comparing the light-evoked current and voltage responses of identified ganglion cells with those produced by current injection. These experiments show that the light-evoked signal is clipped at the bipolar-to-ganglion cell synapse because the synaptic current evoked by illumination with bright light is greater than that which the cell can convert into a change in action potential frequency. Ganglion cell responses to injected current fell into 2 classes: those producing sustained spiking responses and those producing transient responses. Further, this division is correlated with the light response of the cells; those producing transient responses to exogenous current produced transient responses to light, while those with sustained responses to current injection produced sustained responses to light flashes. The voltage-gated currents present in the ganglion cell membrane contribute to information processing in the retina by clipping the light-evoked signal and by producing transcience in the output of the retina.
Mobbs
P
P
Department of Physiology University College London, U.K.
Everett
K
K
Cook
A
A
D000200:Action Potentials / Q000502:physiology; D000557:Ambystoma; D000818:Animals; D004566:Electrodes; D066298:In Vitro Techniques; D008027:Light; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013569:Synapses / Q000502:physiology*