College of Optometry Faculty Proceedings, Presentations, Posters, Speeches, Lectures, etc.

Title

Effects of the location and orientation of receptive-field (RF) surround patches on center-surround interactions in V2 neurons of infant monkeys

Format

Poster

Conference Title

Society of Neuroscience Annual Meeting

Organization/Association/Group

Society of Neuroscience

Location

Washington, D.C. / November 12-16, 2011

Publication Date / Copyright Date

11-13-2011

Abstract

Infant primates do not perform well in visual tasks where oriented contour or texture elements must be linked over extended space in order to perceive a global structure against noisy background, e.g., contour integration (Kiorpes et al, 2003). The neural basis of this immaturity has not been explored. In adult monkeys, we previously showed that stimulation of small, restricted regions of RF surround facilitates the RF center responses of V2 neurons while other regions suppress the center responses depending on the location and the orientation of surround patches, which suggested that V2 neurons may be able to encode colinearity and/or angles sustained by multiple contour elements that extend way beyond the RF center of V2 neurons (Zhang et al, 2008). Here we studied the postnatal development of such facilitatory surround effects in V2 neurons of anesthetized infant monkeys ranging in age between 4 and 16 weeks. A pair of surround patches, matched in size for the unit’s center stimulus, was presented across the RF center at 4 different locations. After determining the optimal location for surround facilitation for each unit, the orientation of surround patches were varied in relation to that for the center stimuli for 0, 45, 90, and 135 degrees. With respect to the position of surround stimuli, the adult-like pattern of facilitatory surround effects did not emerge until 16 weeks of age. Similarly at 8 weeks of age, the facilitatory effects of surround patch orientation were substantially different from that in adults or older infants. These results suggest that the functional connections supporting the RF surround of V2 neurons are considerably immature before 16 weeks of age, and that the inability of low-level extrastriate visual neurons to accurately pool local stimulus feature information over extended space may impose limits on the development of the perceptual decision-making mechanisms downstream.

Disciplines

Optometry

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