Mathematical models for the spatial receptive-field organization of nonlagged
X cells in dorsal lateral geniculate nucleus of cat
G.T. Einevoll,
Physics, ITF, Agricultural University of Norway, 1432 Ås, Norway
P. Heggelund,
Department of Neurophysiology, University of Oslo, 0381 Oslo, Norway
Visual Neuroscience 17, 871-886 (2000)
Abstract
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., 199x)
on response vs. 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.