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Angela C. Voyles, Lynne Kiorpes; A Comparison of VEP and Behavioral Responses to Global Form and Motion in Infant Macaque Monkeys. Journal of Vision 2012;12(9):476. doi: 10.1167/12.9.476.
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© ARVO (1962-2015); The Authors (2016-present)
Adult primates easily integrate global form and motion cues to parse a visual scene, but this ability is not present at birth and slowly develops postnatally. To understand how the development of global perception might be related to postnatal changes in cortical maturation, we compared behavioral and neural responses to global form and motion stimuli in individual infant monkeys. Behavioral measures were made using two-alternative forced-choice psychophysics; neural responses were collected using visually evoked potentials (VEP). We tested infant macaque monkeys (Macaca nemestrina) between the ages of 20 and 40 weeks. Random dot kinematograms were used to establish motion coherence thresholds for both behavioral and electrophysiological measures. For the behavioral task, the animals discriminated the direction of motion of a dot field as a function of coherence; for VEP motion thresholds the same stimulus was swept from high to low coherence. Sensitivity to global form was measured as a difference in response to a structured Glass pattern (of translational, concentric, or radial configuration) and an unstructured random dipole stimulus. This difference was seen as an elevated first harmonic in the VEP, and was compared to the subject’s ability to discriminate a structured Glass pattern from a patch of noise dipoles in the behavioral task. The pattern of results obtained with the VEP measures paralleled the behavioral data for both global form and global motion stimuli. Glass pattern stimuli that elicited behaviorally measurable responses also gave rise to an elevated first harmonic in the VEP. Motion sensitivity thresholds obtained by VEP closely matched those obtained psychophysically. Our behavioral results are consistent with the perceptual limitations seen previously in young monkeys. The parallel pattern of the VEP data suggests that this measure reflects the underlying cortical mechanisms required for the perception of global form and motion.
Meeting abstract presented at VSS 2012
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