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J. Zheng, B. Zhang, C. Nakatsuka, H. Bi, E. L. Smith, Y. M. Chino; Receptive-Field Center-Surround Organization of V1 and V2 Neurons in 2- and 4-Week-Old Monkeys Under Barbiturate and Non-Barbiturate Anesthesia. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3754.
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We previously reported that the RF center-surround organization of V2 neurons is immature during early development (Zhang et al, PNAS, 2005). Because the receptive-field properties of V2 neurons in neonates may be differentially influenced by the type of anesthetic/analgesic agents that are used for acute microelectrode experiments, we compared the response properties of V1 and V2 neurons at 2- and 4-weeks of age and at maturity in monkeys that were anesthetized with barbiturate or non-barbiturate agents.
Seven infant and 6 adult macaque monkeys (Macaca mulatta) were prepared for microelectrode recording experiments. Anesthesia was maintained by continuous infusion of one of the following two anesthetic/analgesic agents: 1) Sodium Pentobarbital (Nembutal, 2 mg/kg/hr), or 2) a mixture of Propofol (4 mg/kg/hr)/Sufentanyl citrate (0.05 µg/kg/hr).
Regardless of which anesthesia was used, the average RF center size of V1 and V2 neurons in 2-week-old infants was about 2-3 times as large as those in adults. The majority of V2 units recorded in 2-week-old infants lacked RF surrounds. Surround suppression in V2 was weaker by a factor of 5-6 in 2-week-old infants and by a factor of about 2 in 4-week-old infants. The average peak-firing rate of V2 neurons was lower in 2-week-old infants by a factor of about 3.0 and by a factor of 2.0 in 4-week-old infants compared to that in adults. The temporal response properties and contrast sensitivity of V1 and V2 neurons in infant monkeys exhibited significant immaturities.
The immature RF center/surround organization and substantial immaturities in other response properties of V1 and V2 neurons found in 2- and 4-week-old infants do not reflect the ‘undesirable effects’ that are unique to barbiturate anesthesia.
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