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Angela Voyles, Anthony M. Norcia, Lynne Kiorpes; Cortical Correlates of Global Form and Motion in Infant Macaque Monkeys: A Comparison of hdEEG and Behavioral Responses. Journal of Vision 2014;14(10):229. doi: 10.1167/14.10.229.
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© ARVO (1962-2015); The Authors (2016-present)
Adult primates easily integrate global form and motion cues over space or space/time, but this ability is not present at birth and slowly develops postnatally. To understand how development of global perception might be related to postnatal cortical maturation, we examined how neural responses, as reflected by high-density visually evoked potentials (VEPs), changed with age. We then compared those neural responses to behavioral capabilities in the same individuals. We tested three infant macaque monkeys (Macaca nemestrina) longitudinally between the ages of 6 and 40 weeks. Sensitivity to global form was evaluated as a difference in response to a coherent Glass pattern versus an incoherent random dipole stimulus; global motion sensitivity was tested using random dot kinematograms (RDKs) of 100% versus 0% coherence. VEP signals were recorded with a 27-electrode custom-designed cap. A differential response to coherent versus incoherent stimuli gave rise to a nonzero first harmonic of the VEP; the extent of the difference was reflected in the first harmonic's amplitude. Behavioral sensitivity to the same patterns was measured using two-alternative forced-choice psychophysics; coherence threshold for discrimination was measured as a function of age. The pattern of neural results paralleled the behavioral data for both global form and global motion stimuli. Glass pattern and RDK stimuli that elicited behaviorally measurable responses also gave rise to increased first harmonic VEP responses (1-tailed t-test, p <.05 for form; p <.01 for motion). First harmonic amplitudes also seemed to increase with age, as behavioral capabilities continued to improve (Pearson correlation, p <.05 for form; p = .056 for motion). Our behavioral results are consistent with the developmental program seen previously in young monkeys. The parallel pattern of VEP development suggests that this measure reflects the maturation of underlying cortical mechanisms required for the perception of global form and motion.
Meeting abstract presented at VSS 2014
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