June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
A Non-Conventional Circuit Mechanism for the Center-Surround Receptive Field of a Retinal Ganglion Cell
Author Affiliations & Notes
  • Jan Homann
    Department of Neuroscience, University of Pennsylvania, Philadelphia, PA
  • Michael Freed
    Department of Neuroscience, University of Pennsylvania, Philadelphia, PA
  • Footnotes
    Commercial Relationships Jan Homann, None; Michael Freed, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 3392. doi:
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Jan Homann, Michael Freed; A Non-Conventional Circuit Mechanism for the Center-Surround Receptive Field of a Retinal Ganglion Cell. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3392.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract
 
Purpose
 

A conventional explanation for the receptive structure of a ganglion cell is that the center and antagonistic surround are provided by a narrow excitatory input and a broader inhibitory input, respectively. Yet the OFF-alpha ganglion cell receives excitatory and inhibitory inputs of about the same spatial extent. Thus the purpose of our study was to map the spatial structure of inhibitory and excitatory inputs to this ganglion cell type to understand how these inputs generate a center/surround receptive field.

 
Methods
 

We constructed a sequence of randomly flickering rings covering the whole receptive field (suggested by Dr. B. Borghuis) (Fig. 1). We recorded excitatory and inhibitory currents by voltage clamping in the whole-cell mode. We generated a spatio-temporal filter and a static nonlinearity for both currents. The amplitude of the filter was plotted against ring radius.

 
Results
 

Spatial plots of both excitatory and inhibitory currents showed center-surround structure (Fig. 2). Excitatory and inhibitory plots were concentric, such that an increase in excitatory conductance was spatially and temporally aligned with a decrease in inhibitory conductance and vice versa. The excitatory current’s center outweighed its surround (c/s = 4.5) whereas the inhibitory current was spatially balanced (c/s = 1.1). Compared to the excitatory current, the inhibitory current was less rectified. At the resting potential, both inhibitory and excitatory conductances contributed equally to currents in the ganglion cell, and thus these currents showed a typical center-surround structure.

 
Conclusions
 

The receptive field of the OFF-alpha cell does not result from a conventional antagonism between inhibition and excitation. Instead inhibitory and excitatory conductances synergize with each other. Presumably then, the center-surround antagonism is pre-formed in the presynaptic bipolar and amacrine cells. The amacrine cells provide the inhibitory input and have a stronger receptive field surround than the bipolar cells. Changing the relative driving forces for excitatory and inhibition conductances may allow a dynamic adjustment of center/surround balance that would serve adaptation to strong contrasts or intensities as has been observed for the cortex.

 
 
Stimulus sequence
 
Stimulus sequence
 
 
Spatio-temporal filter for excitatory and inhibitory currents
 
Spatio-temporal filter for excitatory and inhibitory currents
 
Keywords: 531 ganglion cells • 508 electrophysiology: non-clinical • 673 receptive fields  
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×