Saccade-induced activity of dorsal lateral geniculate nucleus X- and Y-cells during pharmacological inactivation
of the cat pretectum
W. H. Fischer, M. Schmidt & K.-P. Hoffmann
Visual Neuroscience, 15:197-210, 1998
- The influence of neurons projecting from the pretectal nuclear complex to the ipsilateral dorsal lateral geniculate
nucleus (LGNd) was investigated in awake cats. Responses from relay cells in the A-laminae of the LGNd were extracellularly
recorded and analyzed during saccadic eye movements and visual stimulation in association with reversible inactivation
of the ipsilateral pretectum with the GABA agonist, muscimol. Pretectal inactivation (PTI) resulted in spontaneous
nystagmic eye movements in the dark with slow phases directed away from the injected side. In the control situation,
all Y-cells and about two thirds of X-cells were excited during saccades or saccade-like visual stimulation but
one third of X-cells were inhibited. During PTI all recorded X-cells were inhibited, either during saccades or
saccade-like visual stimulation. The PTI-associated inhibition was stronger than in inhibited X-cells in control
experiments only during saccades but not during stimulation with a moving pattern while the eyes were stationary.
In Y-cells a reduction in the response peak width at half-height was seen during PTI, again only during saccades
but not during stimulation with a moving pattern. These results indicate that during saccades the pretecto-geniculate
pathway has a stronger influence on X LGNd relay cells than on Y-cells. The findings are discussed in terms of
saccadic suppression and postsaccadic facilitation.
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