Frequency Responses of Rat Retinal Ganglion Cells

PLoS One. 2016 Jun 24;11(6):e0157676. doi: 10.1371/journal.pone.0157676. eCollection 2016.

Abstract

There are 15-20 different types of retinal ganglion cells (RGC) in the mammalian retina, each encoding different aspects of the visual scene. The mechanism by which post-synaptic signals from the retinal network generate spikes is determined by each cell's intrinsic electrical properties. Here we investigate the frequency responses of morphologically identified rat RGCs using intracellular injection of sinusoidal current waveforms, to assess their intrinsic capabilities with minimal contributions from the retinal network. Recorded cells were classified according to their morphological characteristics (A, B, C or D-type) and their stratification (inner (i), outer (o) or bistratified) in the inner plexiform layer (IPL). Most cell types had low- or band-pass frequency responses. A2, C1 and C4o cells were band-pass with peaks of 15-30 Hz and low-pass cutoffs above 56 Hz (A2 cells) and ~42 Hz (C1 and C4o cells). A1 and C2i/o cells were low-pass with peaks of 10-15 Hz (cutoffs 19-25 Hz). Bistratified D1 and D2 cells were also low-pass with peaks of 5-10 Hz (cutoffs ~16 Hz). The least responsive cells were the B2 and C3 types (peaks: 2-5 Hz, cutoffs: 8-11 Hz). We found no difference between cells stratifying in the inner and outer IPL (i.e., ON and OFF cells) or between cells with large and small somas or dendritic fields. Intrinsic physiological properties (input resistance, spike width and sag) had little impact on frequency response at low frequencies, but account for 30-40% of response variability at frequencies >30 Hz.

MeSH terms

  • Animals
  • Dendrites / metabolism
  • Immunohistochemistry
  • Membrane Potentials
  • Patch-Clamp Techniques
  • Rats
  • Retinal Ganglion Cells / physiology*
  • Synaptic Potentials*

Grants and funding

This work was funded by National Health and Medical Research Council of Australia, 585440; Australian Research Council, Discovery Project, DP0881247; Australian Research Council, Special Research Initiative (SRI) in Bionic Vision Science and Technology grant to Bionic Vision Australia (BVA), SR1000005; and ARC Centre of Excellence for Integrative Brain Function, CE140100007. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.