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Bin Zhang, Jianghe Zheng, Earl Smith, Yuzo Chino; Mature transient responses of V2 neurons in 2-Week-Old infant monkeys. Journal of Vision 2007;7(9):77. doi: 10.1167/7.9.77.
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© ARVO (1962-2015); The Authors (2016-present)
Previous studies reported that the onset firing of V1 neurons during the first 150–200 msec of stationary stimulus presentation, carry as much information, if not more, as the sustained component (e.g., Muller et al, 2001). In this study, we investigated the normal maturation of response properties in V1 and V2 neurons by comparing the relative development of transient versus sustained components of cell's responses. In 13 infant and 4 adult anesthetized and paralyzed macaque monkeys, microelectrode recording methods were employed to examine the responses of V1 and V2 neurons to stationary sine wave gratings of high contrast (80%) optimized for orientation, spatial frequency and size. All receptive fields were located within 6° of the center of the fovea. At 2 weeks of age the transient components of neuronal responses in V1 and V2 to high-contrast, stationary gratings were as strong as in adults. However, the sustained responses of these neurons were abnormally suppressed or absent in infant monkeys largely due to robust contrast adaptation. Maximum detectability (d') in infant monkeys, achieved during the first 200 msec of stimulus presentation, was as strong as those in adult monkeys, while maximum detectability (d'), achieved during the last 100 msec of stimulus presentation, was significantly lower in 2-week-old infants than those in adults. As early as 2 weeks of age, most V1 and V2 neurons achieved maximum detectability (d') to high contrast stationary stimuli during the first 200 milliseconds stimulus presentation. These results suggest that neonates and young infants may perform better than previously thought for the visual tasks where prolonged fixation on targets is not required, but instead, the direction of saccades is used for detection of spatially simple, high contrast targets.
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