Receptive Field Mosaics of Parasol and Midget Ganglion Cells in the Primate Retina

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Receptive Field Mosaics of Parasol and Midget
Ganglion Cells in the Primate Retina

• Jeff Gauthier, PhD student
• Computational Neurobiology, UC-San Diego
• E.J. Chichilniskys lab,
• Salk Institute, San Diego, CA

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Research Groups

• E.J. Chichinlisky
• Salk Institute

Alan Litke UC-Santa Cruz
Greg Field Jon Shlens Eric Frechette
Dumitru Petrusca Sasha Sher Matthew Grivich
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Functional Characterization of Parasols and
Midgets

• What is the relationship between receptive field
  (RF) and dendritic field (DF)?
• How does coverage of parasols and midgets differ?
• Are the ON-OFF asymmetries of parasols also found
  in midgets?

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Multielectrode Array Recording
Ganglion cell spikes are recorded with an array
of 512 extracellular electrodes.
Array designed and built by Alan Litkes group,
UC-Santa Cruz.
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Example STAs
spatial component
temporal component
OFF
ON
parasol
contrast
midget
time before spike (msec)
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Stimulus
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Example STA
In order to compare many cells, each STA is
parameterized by fitting a model.
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RFs of all cells
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Classification
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Functional Characterization of Parasols and
Midgets
What is the relationship between RF and DF?
How does the coverage of parasol and midget RFs
differ?
Are the ON-OFF asymmetries of parasols also found
in midgets?
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Parasols have more DF overlap than midgets
Parasol Dendritescoverage of 3-4
Midget Dendritescoverage of 1
Dacey Brace (1992), Dacey (1993)
Does DF coverage predict RF coverage? Is RF
coverage different for parasols and midgets?
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Parasol and midget RFs seem to have the same
coverage
What is the relationship between DF and RF?
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Mapping RF onto DF
Parasol and midget RF diameters taken from5,643
cells in 18 preparations.
diameter (um)
eccentricity (mm, temp. eq.)
Horizontal bars indicate eccentricity measurement
error.Vertical bars indicate s.d. of RF diameter
within one retina.DF diameters from Watanabe
Rodieck 1989.
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Interpretation

• By what mechanism are parasol RFs relatively
  shrunk?
• More inhibition on parasols peripheral dendrites
  (Grunert 1999).
• Bipolars feeding parasols pool from relatively
  smaller area.
• More attenuation of distal inputs?

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Functional Characterization of Parasols and
Midgets
What is the relationship between RF and DF?
How does the coverage of parasol and midget RFs
differ?
Are the ON-OFF asymmetries of parasols also found
in midgets?
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Parasol midget mosaics
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Parasol midget mosaics
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Is coverage really the same?a parametric test
normalized nearest neighbor distancedistance
from center to center divided by cell size
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Is coverage really the same?a non-parametric test
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Is coverage really the same?a non-parametric test
pixels covered by exactly 1 cell
threshold relative to peak
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Interpretation

• Higher parasol DF coverage and shrunken RF
  perfectly compensate to give same coverage as
  midget, suggesting this coverage factor is the
  aim of development.

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Functional Characterization of Parasols and
Midgets
What is the relationship between RF and DF?
different for each
How does the coverage of parasol and midget RFs
differ?
Are the ON-OFF asymmetries of parasols also found
in midgets?
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ON-OFF Asymmetries
RF diameter (um)
time to peak response (msec)
Data taken from 5643 cells from 18 retinas.Bars
indicate standard deviation within one retina.
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Interpretation

• Similarity of ON and OFF asymmetries for parasol
  and midgets suggest they arise prior to ganglion
  cell processing

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Functional Characterization of Parasols and
Midgets
What is the relationship between RF and DF?
different for each
How does the coverage of parasol and midget RFs
differ?
same
Are the ON-OFF asymmetries of parasols also found
in midgets?
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Control for pixel size
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Parasol-Midget relationship
size (um)
time to peak response (msec)
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Functional Characterization of Parasols and
Midgets

• Parasol dendrites have much more overlap than
  midget dendrites. Does dendritic field (DF)
  overlap predict receptive field (RF) overlap?
• What is the relationship between RF and DF size
  in parasols? Is it the same for midgets?
• Parasols have ON-OFF asymmetries ON-parasols are
  larger and faster and OFF-parasols. Do the same
  asymmetries hold for ON- and OFF-midgets?

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Conclusions

• Relationship between RF and DF is different for
  parasols and midgets
• Parasols and midgets have same RF coverage
• Parasols and midgets have same ON-OFF asymmetries