Difference of Gaussians (DOG) model.

<p>(A) The center-surround receptive filed organization is assumed to be fitted by two Gaussian curves: the narrower positive Gaussian representing the excitatory center or the CRF, while the broader negative Gaussian represents the inhibitory surround or the nCRF. K_e and a represent the strength and the space constants for the CRF, and K_i and b, those of the nCRF. The summation profile (R) of the model is represented as the difference of the two integrals of Gaussians. (B) A V1 neuron with suppressive summation. Dashed and dotted curves represent integrals of the excitatory and inhibitory components and the solid curve the linear combination of the two components that best fits the summation data.</p

The histogram of changes in strength of surround suppression for FSUs and RSUs.

<p>The △SI indicate the difference between SI_high and SI_low. The arrows indicate the average, which was 0.02 for FSUs and 0.08 for RS-Units (P >0.05).</p

Difference of Gaussians (DOG) model.

<p>(A) The center-surround receptive filed organization is assumed to be fitted by two Gaussian curves: the narrower positive Gaussian representing the excitatory center or the CRF, while the broader negative Gaussian represents the inhibitory surround or the nCRF. K_e and a represent the strength and the space constants for the CRF, and K_i and b, those of the nCRF. The summation profile (R) of the model is represented as the difference of the two integrals of Gaussians. (B) A V1 neuron with suppressive summation. Dashed and dotted curves represent integrals of the excitatory and inhibitory components and the solid curve the linear combination of the two components that best fits the summation data.</p

The spatial summation curves of two V1 neurons at high and low contrast.

<p>The red and blue line represents a FSU and a RSU for each. The curve with solid symbols represents the spatial summation curve measured at high contrast and the curve with open symbols at low contrast.</p

Classification of the FS-Units and RS-Units.

<p>(A) Shown were representative traces, recording from two neurons in V1 cat. (B) The recorded action potential waveforms were averaged and normalized. (C) The distribution of waveform durations was significant bimodal according to Hartigan’s dip test (P < 0.01). (D) The scatterplots of each cell’s peak firing rate versus spike duration. The average of peak firing rates for FSUs was significant stronger than those of RSUs (P = 0.0003). The blue and red solid line indicate the average of peak firing rate of RSUs and FSUs for each.</p

The scatter plot of the estimates of surround suppression at high contrast versus low contrast.

<p>The solid circle and hollow diamond indicate RSUs and FSUs, respectively.</p