Purchase this article with an account.
Seunghoon Lee, Jimmy Zhou; Patch-clamp Characterization of Conventional Amacrine Cell Types in Wholemount Rabbit Retina. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1608.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
While morphological classification of amacrine cell (AC) types is nearly complete, the physiological correlates of most AC types remain unclear, due largely to the lack of direct information from these cell types. Here, we made patch-clamp recordings from over thirty types of ACs to characterize the excitatory and inhibitory receptive field (RF) properties as well as intrinsic voltage-gated currents.
Whole-cell patch-clamp recording were made from functionally mature ACs in the flat-mount rabbit retina. The spatial properties of the excitatory and inhibitory RFs were investigated at reversal potentials for Cl- and non-selective cations and compared with the dendritic field of the cells.
ACs were classified into three different groups, narrow (NF)-, medium (MF)-, and wide-field (WF) ACs by their morphology. The spatial extent of the inhibitory RF varied greatly among different AC types, whereas that of the excitatory RF generally matched the dendritic field of the cells. Specifically, about half of the NFAC types received long-range inhibition (>500 um) well beyond their RF center (50 um), while the other NFAC types exhibited spatially matched center-surround structures (50 um). In contrast, most MFAC types received short- or long-range inhibitory inputs from RF surround that is spatially larger than their dendritic field. Interestingly, in over 50% of WFAC types, the spatial extent of the excitatory RF was larger than that of the inhibitory RF. Voltage-gated Na+-like currents were found in nearly all AC types except a few cell types, which included On- and Off-starburst amacrine cells. While amplitudes of the currents varied greatly among different AC types, around 30% of NFACs, 45% of MFACs, and 55% of WFACs elicited more than 500 pA of the Na+-like currents. These functional diversities of ACs were also found in the patterns (on vs. off) and kinetics (sustained vs. transient) of the excitatory and inhibitory inputs. For instances, WFAC1-2, one type of orientation-biased cell, received sustained on-excitatory and sustained on-inhibitory currents, whereas WFAC1-3, another orientation-biased cell, received transient on-excitatory, sustained off-excitatory, and sustained on-inhibitory currents under annulus illumination. The kinetics and frequency of spontaneous synaptic currents in different types of ACs were as diverse as the light-evoked input currents in these cells.
Based on the intrinsic currents and RF organizations, nearly all morphologically distinct AC types showed distinct physiological properties, suggesting unique roles of each AC types in visual processing.
This PDF is available to Subscribers Only