VOLTAGE DEPENDENCY OF LIGHT-EVOKED ON-OFF TRANSIENT AMACRINE CELL RESPONSES IN CARP RETINA

The voltage dependency of the ON and the OFF components of transient a macrine cell responses was studied using two-electrode voltage-clamp a nd current-clamp techniques in the isolated retina of the carp. The tw o independent approaches gave similar data. When cells were voltage cl amped near their resting potentials, both response components were ass ociated with transient inward currents. Hyperpolarization increased re sponse size (current or voltage) whilst depolarization decreased it. R esponse reversal, or a tendency for it, occurred at membrane potential s significantly more positive than the resting level with some quantit ative variability. These data support the view that the ON-OFF depolar izations represent basically excitatory postsynaptic potentials and th at the transience of the responses cannot mainly be due to any voltage -dependent conductance.