Spatial receptive fields of relay cells in dorsal lateral
geniculate nucleus (dLGN) have commonly been modeled as
a difference of two Gaussian functions. We present alternative
models for dLGN cells which take known physiological couplings
between retina and dLGN and within dLGN into account. The
models include excitatory input from a single retinal ganglion
cell and feedforward inhibition via intrageniculate
interneurons. Mathematical formulas describing the receptive
field and response to circular spot stimuli are found both
for models with a finite and an infinite number of ganglion-cell
inputs to dLGN neurons. The advantage of these models compared
to the common difference-of-Gaussians model is that they,
in addition to providing mathematical descriptions of the
receptive fields of dLGN neurons, also make explicit contributions
from the geniculate circuit. Moreover, the model parameters
have direct physiological relevance and can be manipulated
and measured experimentally. The discrete model is applied
to recently published data (Ruksenas et al., 2000) on response
versus spot-diameter curves for dLGN cells and
for the retinal input to the cell (S-potentials). The models
are found to account well for the results for the X-cells
in these experiments. Moreover, predictions from the discrete
model regarding receptive-field sizes of interneurons,
the amount of center-surround antagonism for interneurons
compared to relay cells, and distance between neighboring
retinal ganglion cells providing input to interneurons,
are all compatible with data available in the literature.
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