Central neural influences on the human retina during selective attention

Abstract

Two controversial issues were investigated. One concerned the question of whether cen· trifugal fibers project to the human retina, and the other, the question of whether precortical fil· ters which differentially transmit relevant and irrelevant information during selective attention exist. The issues were addressed jointly by studying the effects of selective attention on evoked responses obtained from the retina and over the occipital cortex. Selective attention was manipulated by requiring subjects to respond to stimuli presented at various locations in the visual field while attempting to ignore stimuli presented at other locations. Retinal responses to stimuli presented at attended to locations were found to be larger than those at unattended to locations. A similar result was obtained for responses recorded over the occipital cortex. The results are interpreted as follows: (1) They support the hypothesis that sustained voluntary at· tention to specific locations in space is mediated, at least partly, by centrally controlled cen· trifugal pathways which differentially modify synaptic transmission at a precortical level; (2) such differential alteration can occur as far peripherally as the retina; and (3) such alteration at the retinal level necessarily requires the existence of centrifugal optic nerve fibers. The results are discussed within the context of existing evidence bearing on the issues.

Activity Versus Reactivity in Psychology and Neurophysiology

“…It is obvious that the changes of this activity in relation to the phases of the behavior can be accomplished only by efferent influences on the retina. At present, much data has accumulated demonstrating the existence of efferent fibers in the optic tract and of efferent influences on the retina in different species ranging from frogs to man (e.g., Hasselt, 1972;Livingston, 1978;Eason, Oakley, &Flowers, 1983) and including rabbits (Cragg, 1962). However, the significance of these influences was usually either considered unclear or explained as modulation of peripheral sensory elements' responses to the stimuli of the specific modality, related, for example, to intermodal interaction (Granit, 1955;Santini, 1976;Witkovsky, 1971).…”

Neural mechanisms of visual selective attention

“…It has been hypothesized that the early ERP attention effects, such as the PI amplitude modulation, may reflect processing in the visual cortex, subcortical structures, or even in the retina itself (e.g., Eason, 1981;Eason, Oakley, & Flowers, 1983;Harter & Aine, 1984;Van Voorhis & Hillyard, 1977). However, little direct evidence exists that links these attention-sensitive ERPs to specific brain structures.…”

Intermodal spatial attention differs between vision and audition: An event-related potential analysis

“…attention to visual stimuli, these effects comprise a modulation of the early occipital P1 and N1 waveforms for relevant stimuli, contralateral to the location of the stimulus, an effect that is known as "Sensory Gain"~Eason, 1981;Eason, Harter, & White, 1969;Eason, Oakley, & Flowers, 1983;Harter, Aine, & Schroeder, 1982;Hillyard, Simpson, Woods, Van Voorhis, & Münte, 1984;Luck & Hillyard, 1994;Mangun & Hillyard, 1988;Neville & Lawson, 1987;Rugg, Milner, Lines, & Phalp, 1987!. The effects of spatial attention following early P1 and N1 modulations are less consistent, however. Some studies have reported modulations of occipital P2 and N2 waves, and sometimes the P3 component~Eason et al, 1969P3 component~Eason et al, , 1983Mangun & Hillyard, 1988!.…”