Anthony Hernández Vázquez

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Overview of Coombe’s Paper

on Monday, July 16th, 2018 11:39

LMC L1 and L2 Paper

(Coombe, P.E., 1986)


  1. mass electrical response of the eye
  2. waveform consisting of summed extracellular potentials produced by retinula cells and postsynaptic neurons
  3. recorded by electrodes
  4. waveform consists of on transient, negative sustained potential and off transient

L1 and L2

  1. Two main reasons to select study upon these two:
    1. Only lamina neurons which are known electrophysiology
    2. Intracellular waveforms roughly correspond to ERG transients

Vam mutants

  1. Vam = Vacuolar medulla
  2. Semi-dominant mutation (Incomplete dominance)
  3. Characterized by formation of large vacuoles and absence of ERG transients

(Electron Micrographs from the lamina) (ERG)

ERG waveform and LMC degeneration

  1. No wt showed degeneration of LMC
  2. Negative nonlinear relationship between % of LMC degeneration and the size of on/off transients in Vam flies



  1. Previous work has shown age-specific degeneration of LMC in the lamina.
  2. Signs of degeneration start to appear in the form of large vacuoles in medulla and lamina.
  3. LMC may be responsible for ERG transients