Vorobyov Vasily, Schwarzkopf D Samuel, Mitchell Donald E, Sengpiel Frank
Cardiff School of Biosciences, Cardiff University, Cardiff CF10 3US, UK.
Eur J Neurosci. 2007 Dec;26(12):3553-63. doi: 10.1111/j.1460-9568.2007.05946.x. Epub 2007 Dec 4.
While continuous monocular deprivation (MD) of patterned vision causes severe loss of visual cortical responses and visual acuity in the affected eye, these effects can be avoided by providing brief daily periods of binocular exposure [BE; D.E. Mitchell et al. (2003) Curr. Biol., 8, 1179-1182; D.E. Mitchell et al. (2006) Eur. J. Neurosci., 23, 2458-2466; D.S. Schwarzkopf et al. (2007) Eur. J. Neurosci., 25, 270-280]. In order to analyse binocular mechanisms involved in this phenomenon, we studied neuronal responses in primary visual cortex to binocular disparity stimuli in cats that had experienced mixed daily visual exposure (i.e. different amounts of daily binocular and monocular exposure). To examine whether binocular responses are as reliable in MD as in normal animals, we analysed single-trial responses to spatial phase disparity stimuli. In cats with various amounts of daily binocular experience (3.5 h, 7 h or 12 h) alone, about half of neurons (47.9%) showed reliable phase-specific binocular responses in two consecutive trials. The percentage of phase-selective cells was reduced in cats with mixed visual exposure with a decrease in the duration of daily BE. Within these neurons, a 'stable' cell population, i.e. with identical relative phases eliciting the strongest and weakest responses in two trials, was also reduced. In other words, the responses of neurons recorded from deprived animals were more likely to show different preferred phases on successive trials, although their amplitude ratios in both trials were about equal. We suggest that the detrimental effect of MD on binocular vision may begin, at least in part, with a subtle disruption of the mechanism involved in discrimination of binocular disparity signals.
虽然对有图案视觉的持续单眼剥夺（MD）会导致受影响眼睛的视皮层反应和视敏度严重丧失，但通过每天提供短暂的双眼暴露期[BE；D.E.米切尔等人（2003年）《当代生物学》，8，1179 - 1182；D.E.米切尔等人（2006年）《欧洲神经科学杂志》，23，2458 - 2466；D.S.施瓦茨科普夫等人（2007年）《欧洲神经科学杂志》，25，270 - 280]，这些影响是可以避免的。为了分析参与这一现象的双眼机制，我们研究了经历每日混合视觉暴露（即每日不同量的双眼和单眼暴露）的猫的初级视皮层对双眼视差刺激的神经元反应。为了检验双眼反应在MD动物中是否与正常动物一样可靠，我们分析了对空间相位视差刺激的单试次反应。在仅具有不同每日双眼暴露时长（3.5小时、7小时或12小时）的猫中，约一半的神经元（47.9%）在连续两次试验中表现出可靠的相位特异性双眼反应。随着每日BE时长的减少，在经历混合视觉暴露的猫中相位选择性细胞的百分比降低。在这些神经元中，一个“稳定”的细胞群体，即在两次试验中引发最强和最弱反应的相对相位相同的群体，也减少了。换句话说，从剥夺动物记录的神经元反应在连续试验中更有可能表现出不同的偏好相位，尽管两次试验中的振幅比大致相等。我们认为，MD对双眼视觉的有害影响可能至少部分始于对双眼视差信号辨别机制的细微破坏。
