Abstract
Purpose :
Recent advances in multi-electrode array (MEA) recordings and analysis have provided an unprecedented opportunity to simultaneously study the properties of hundreds of neurons of diverse types in the primate retina. While these advances allow us to record from novel cell types, their correspondence with anatomically identified types is generally unknown. Here, we begin to bridge this gap by comparing cell properties of cells recorded on a MEA to those of cells recorded and anatomically identified using single-cell patch recordings.
Methods :
MEA recordings were performed from the peripheral macaque monkey retina. The spike-triggered average (STA) of each cell was calculated from responses to flickering checkerboards and used to summarize its spatial, temporal, and chromatic properties. Cell types were identified by clustering their functional properties. Substantial errors due to spike sorting were ruled out by the observed stereotypical properties of cells across the electrode array, refractory periods, spatiotemporal structure of electrical footprints, and mosaic organization of receptive fields (RFs) within each type. For patch recordings, cells were targeted for recording based on soma shape and spike responses to contrast steps. Cell type was confirmed from biocytin or neurobiotin fills and recovery of cellular morphology following antibody staining and confocal imaging.
Results :
Cells of each type recorded using the MEA formed mosaics and exhibited unique properties, including the interspike-interval distribution, STA time course, RF size, spatio-chromatic selectivity, and relative strength of RF center and surround. These properties were compared to properties of identified cell types in single-cell recordings. In addition to the well-known ON & OFF parasol, ON & OFF midget, ON & OFF smooth monostratified, and small bistratified retinal ganglion cells, we were able to identify broad thorny cells, recursive bistratified cells, large bistratified cells, and A1 polyaxonal amacrine cells in MEA recordings. We are currently investigating the identity of over two dozen additional spiking cell types that appear in MEA recordings.
Conclusions :
We have established the morphological identity of multiple novel functional cell types by comparing physiological properties of identified cells recorded using patch recordings with cell populations recorded using the MEA.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.