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X. Tao, J. Zheng, B. Zhang, C. Nakatsuka, H. Bi, E. L. Smith, III, Y. M. Chino; Effects of Commonly Used Anesthesia on Responses of V1 and V2 Neurons in Monkeys. Invest. Ophthalmol. Vis. Sci. 2007;48(13):3753.
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© ARVO (1962-2015); The Authors (2016-present)
The type of anesthesia used for microelectrode recording experiments in visual cortex is often invoked to explain conflicting results among studies. In this study, we examined the response properties of V1 and V2 neurons in mature monkeys using three most commonly used anesthetic/analgesic agents while keeping other experimental variables as constant across subjects as possible.
Seven adult macaque monkeys (Macaca mulatta) were prepared for microelectrode recording experiments and artificially ventilated with a mixture of 59% N2O, 39% O2, and 2% CO2. Anesthesia was maintained by the continuous infusion of one of the following three anesthetic/analgesic agents: 1) Sodium pentobarbital (Nembutal, 2 mg/kg/hr), 2) a mixture of Propofol (4 mg/Kg/hr) and Sufentanyl citrate (0.05ug/kg/hr), or 3) Sufentanyl citrate (4ug/kg/hr). Tungsten-in-glass microelectrodes were used to isolate the activity from individual V1 and V2 neurons.
The responsiveness of V1 and V2 neurons, determined by measuring the contrast threshold, contrast gain and the peak firing rate of individual neurons, was similar among the monkeys that received three different anesthetic agents. Temporal resolution and visual latency of individual neurons did not substantially differ in V1 or V2 under the three anesthetic conditions. Receptive-field (RF) center-surround organization of individual V1 and V2 neurons was largely unaffected by different agents. Our data obtained under Sufentanyl anesthesia were similar to those previously reported by other investigators using the same agent.
We conclude that differences in anesthesia may not be the primary factor contributing to contradictory results in V1 or V2 between studies. Instead, maintaining the physiological conditions of experimental animals and their visual brain optimal and employing highly efficient sampling procedures may be more important for obtaining reliable and repeatable data from anesthetized animals than the type of anesthesia used for recording experiments.
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