Enroth-Cugell and Freeman '87 Y-cell model

Below are some notes on Enroth-Cugell and Freeman's 87 model of the Y-cell.

• Stages
  • Center-surround subunits
    • A difference of Gaussians with the added allowance for different phases or midpoints for the two Gaussians.
  • Rectification
    • y = x + q x^2
  • Spatial Pool
  • Contrast Gain Control
    • "a feed-back loop in which there is a temporal low-pass filter in the feed-back arm."
    • gain (g) of the feedback is proportional to the dc
• A list of example parameters
  Model 1508 on Y cell page 71
  • Center-surround subunits
    • Center
      • Amplitude: 1170 spikes/second/contrast unit
      • Phase: -2 degrees
      • radius: .21 degrees
    • Surround
      • Amplitude: 1020 spikes/second/contrast unit
      • Phase: 155 degrees
      • radius: 2 degrees
  • Rectification
    • Constant (q): 0.0040 s/impulse
  • Spatial Pool
    • Pool radius: .77 degrees
  • Contrast Gain Control
    • Time constant: 80 msec
    • Feedback gain: .11
  • Mean firing rate: 25 spikes/sec

  Model Parameters

  Parameters		Cell #1508	Cell #1711	Cell #1504
  Subunit Center	Amplitude (impulse/sec/contrast)	1170	78,800	212
  	Phase (degrees)	-2	-18	-171
  	radius (degrees)	.21	.2	.13
  Subunit Surround	Amplitude (impulse/sec/contrast)	1020	78,300	123
  	Phase (degrees)	155	162	-23
  	radius (degrees)	2	.42	2.9
  Rectification constant	(sec/impulse)	.004	8x10^-6	.02
  Spatial Pool radius	(degrees)	.77	1.3	.84
  Contrast Gain	time constant (ms)	80	80	80
  	Feedback gain	.11	.08	.03
  Mean Firing Rate	(impulses/sec)	25	12	4

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