Effects of the concomitant activation of ON and OFF retinal ganglion cells on the visual thalamus: Evidence for an enhanced recruitment of GABAergic cells

Giovanni Montesano, Marcello Belfiore, Maddalena Ripamonti, Alessandro Arena, Jacopo Lamanna, Mattia Ferro, Vincenzo Zimarino, Alessandro Ambrosi, Antonio Malgaroli

Research output: Contribution to journalArticlepeer-review

Abstract

A fundamental question in vision neuroscience is how parallel processing of Retinal Ganglion Cell (RGC) signals is integrated at the level of the visual thalamus. It is well-known that parallel ON-OFF pathways generate output signals from the retina that are conveyed to the dorsal lateral geniculate nucleus (dLGN). However, it is unclear how these signals distribute onto thalamic cells and how these two pathways interact. Here, by electrophysiological recordings and c-Fos expression analysis, we characterized the effects of pharmacological manipulations of the retinal circuit aimed at inducing either a selective activation of a single pathway, OFF RGCs [intravitreal L-(+)-2-Amino-4-phosphonobutyric, L-AP4] or an unregulated activity of all classes of RGCs (intravitreal 4-Aminopyridine, 4-AP). In in vivo experiments, the analysis of c-Fos expression in the dLGN showed that these two manipulations recruited active cells from the same area, the lateral edge of the dLGN. Despite this similarity, the unregulated co-activation of both ON and OFF pathways by 4-AP yielded a much stronger recruitment of GABAergic interneurons in the dLGN when compared to L-AP4 pure OFF activation. The increased activation of an inhibitory thalamic network by a high level of unregulated discharge of ON and OFF RGCs might suggest that cross-inhibitory pathways between opposing visual channels are presumably replicated at multiple levels in the visual pathway, thus increasing the filtering ability for non-informative or noisy visual signals.

Original languageEnglish
Pages (from-to)1-19
Number of pages19
JournalFrontiers in Neural Circuits
Volume9
Issue numberNovember
DOIs
Publication statusPublished - Nov 24 2015

Keywords

  • 4-aminopyridine
  • 4-AP
  • C-Fos
  • DLGN
  • Inhibitory neurons
  • NeuN
  • Retina
  • Visual thalamus

ASJC Scopus subject areas

  • Neuroscience (miscellaneous)
  • Cellular and Molecular Neuroscience
  • Sensory Systems
  • Cognitive Neuroscience

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