Linear mechanistic models for the dorsal lateral geniculate nucleus
of cat probed using drifting-grating stimuli
Gaute T. Einevoll,
Physics, ITF, Agricultural University of Norway, 1432 Ås, Norway
Hans E. Plesser,
Physics, ITF, Agricultural University of Norway, 1432 Ås, Norway
Network: Comput. Neural Systems 13, 503-530 (2002)
Abstract
Experiments with sinusoidal visual stimuli in the early visual
pathway have traditionally been interpreted in terms of descriptive
filter models. We present an alternative mechanistic approach for
interpretation of this type of data recorded from X cells in the
dorsal lateral geniculate nucleus (dLGN) of cat. A general, linear,
rate-based mathematical expression for the geniculate transfer
ratio, i.e., the ratio between the first harmonic components of the
output of a geniculate relay cell and its retinal input, is derived.
In linear theory this ratio is independent of the signal processing
occurring at the retinal level. Further, the ratio is
straightforwardly accessible in experiments due to the presence of
S-potentials, representing the retinal input, in extracellular
recordings from dLGN. The expression accounts for feedforward
inputs from retina and intrageniculate interneurons as well as
feedback inputs from cortex and the thalamic reticular nucleus and
can be used to experimentally test different mechanistic models for
the geniculate circuitry. Two examples of this are considered: a
purely feedforward model incorporating relay-cell inputs from
retinal ganglion cells and interneurons, and a model including
cortical feedback inhibition of relay cells via intrageniculate
interneurons.