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Spatial Asymmetry and Temporal Delay of Inhibitory Amacrine Cells Produce Directional Selectivity in Retina

  • Amane Koizumi
  • Misako Takayasu
  • Hideki Takayasu
  • Yutaka Shiraishi
  • Akimichi Kaneko
Conference paper
  • 147 Downloads
Part of the Keio University International Symposia for Life Sciences and Medicine book series (KEIO, volume 11)

Abstract

Directional selectivity is a unique function relating to agility that some portion of ganglion cells in the retina fire only for moving light signals with specific direction and speed [1]. Taylor et al. [2] showed that inhibitory synaptic outputs from inhibitory amacrine cells to directional selective ganglion cells are playing a critical role in directional selectivity in the rabbit retina. We previously reported that dendrites of inhibitory amacrine cells have active regenerative properties to propagate action potentials [3]. γ-Aminobutyric acid releases from the dendrites were driven by action potential propagation into the dendrites. The speed of action potential propagation in dendrites of amacrine cells was approximately 10 m/s, which is one tenth slower than that of an axon. Thus, initiation and propagation of action potentials on amacrine cell dendrites cause a temporal delay in synaptic outputs to ganglion cells. In addition, asymmetric expansion of dendrites of amacrine cells causes asymmetric synaptic outputs to ganglion cells. Here, we established a novel hypothesis that these features of inhibitory amacrine cells might play an important role in forming directional selectivity. In order to clarify the mechanism of directional selectivity, we numerically analyzed the whole retina activity using a recently developed neural-network simulation powered by NEURON, which models each cell’s electrophysiological activity. All known experimental facts reported to date are explained in a consistent manner by our hypothesis on the connection of cells that direction-selective ganglion cells are receiving inhibitory synaptic inputs from amacrine cell dendrites with a random spatial asymmetry and a temporal delay.

Key words

Directional selectivity Simulation Amacrine cell 

References

  1. 1.
    Barlow HB, Hill RM, Levick WR (1964) Retinal ganglion cells responding selectively to direction speed of image motion in rabbit. J Physiol (Lond) 173: 377Google Scholar
  2. 2.
    Taylor WR, He S, Levick WR, et al. (2000) Dendritic computation of direction selectivity by retinal ganglion cells. Science 289: 2347–2350PubMedCrossRefGoogle Scholar
  3. 3.
    Yamada Y, Koizumi A, Iwasaki E, et al. (2002) Propagation of action potentials from the soma to individual dendrite of cultured rat amacrine cells is regulated by local GABA input. J Neurophysiol 87: 2858–2866PubMedGoogle Scholar

Copyright information

© Springer-Verlag Tokyo 2003

Authors and Affiliations

  • Amane Koizumi
    • 1
  • Misako Takayasu
    • 2
  • Hideki Takayasu
    • 3
  • Yutaka Shiraishi
    • 1
  • Akimichi Kaneko
    • 1
  1. 1.Department of Physiology, School of MedicineKeio UniversityShinjuku-ku, TokyoJapan
  2. 2.Department of Complex SystemsFuture University-HakodateHakodate, HokkaidoJapan
  3. 3.SONY Computer Science LaboratoryShinagawa-ku, TokyoJapan

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