ISSN:
1432-1106
Keywords:
Eye movements
;
Lateral geniculate nucleus
;
Mesencephalic reticular formation
;
Pretectal area
;
Visual system
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary 1. In squirrel monkeys or macaques under barbiturate anesthesia one or a few electrical pulses applied to the mesencephalic reticular formation or pretectal area alters synaptic transmission through the lateral geniculate nucleus, as tested by magnitude of response in optic radiation to stimulation of optic tract. The effect begins within 5–10 msec after the start of the mesencephalic stimulation and is usually biphasic. Initial inhibition lasts for about 30 msec and is then replaced by facilitation which peaks around 70–120 msec and may endure as much as 1 sec. 2. The major site of the effect is upon the lateral geniculate nucleus, and both magno- and parvocellular elements are involved. Only rarely does the mesencephalic stimulation directly alter excitability of striate cortex. 3. In this respect, as well as in the strong facilitation of photically elicited responses, the effects in primates differ significantly from those in cats. 4. Although the inhibition observed in the lateral geniculate nucleus meets criteria commonly believed to signify a presynaptic origin, several paradoxical facts (see Discussion) must be resolved before this interpretation can be secure. 5. It is hypothesized that the observed effects arise primarily from intrusion into a system normally concerned with the acquisition of visual information by ocular saccades. Saccadic gating of transmission through the lateral geniculate nucleus would distinguish self-generated visual signals from similar, extrinsically initiated signals, and would thus constitute the “corollary discharge”.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00234723
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