Scholl Benjamin, Pattadkal Jagruti J, Priebe Nicholas J
Max Planck Florida Institute, Jupiter, Florida 33458, and.
Center for Perceptual Systems, Department of Neuroscience, College of Natural Sciences, University of Texas at Austin, Austin, Texas 78712.
J Neurosci. 2017 Jul 5;37(27):6517-6526. doi: 10.1523/JNEUROSCI.1193-16.2017. Epub 2017 Jun 2.
Experiences during the critical period sculpt the circuitry within the neocortex, leading to changes in the functional responses of sensory neurons. Monocular deprivation (MD) during the visual critical period causes shifts in ocular preference, or dominance, toward the open eye in primary visual cortex (V1) and disrupts the normal development of acuity. In carnivores and primates, MD also disrupts the emergence of binocular disparity selectivity, a cue resulting from integrating ocular inputs. This disruption may be a result of the increase in neurons driven exclusively by the open eye that follows deprivation or a result of a mismatch in the convergence of ocular inputs. To distinguish between these possibilities, we measured the ocular dominance (OD) and disparity selectivity of neurons from male and female mouse V1 following MD. Normal mouse V1 neurons are dominated by contralateral eye input and contralateral eye deprivation shifts mouse V1 neurons toward more balanced responses between the eyes. This shift toward binocularity, as assayed by OD, decreased disparity sensitivity. MD did not alter the initial maturation of binocularity, as disparity selectivity before the MD was indistinguishable from normal mature animals. Decreased disparity tuning was most pronounced in binocular and ipsilaterally biased neurons, which are the populations that have undergone the largest shifts in OD. In concert with the decline in disparity selectivity, we observed a shift toward lower spatial frequency selectivity for the ipsilateral eye following MD. These results suggest an emergence of novel synaptic inputs during MD that disrupt the representation of disparity selectivity. We demonstrate that monocular deprivation during the developmental critical period impairs binocular integration in mouse primary visual cortex. This impairment occurs despite an increase in the degree to which neurons become more binocular. We further demonstrate that our deprivation did not impair the maturation of disparity selectivity. Disparity selectivity has already reached a matured level before the monocular deprivation. The loss of disparity tuning is primarily observed in neurons dominated by the open eye, suggesting a link between altered inputs and loss of disparity sensitivity. These results suggest that new inputs following deprivation may not maintain the precise spatial relationship between the two eye inputs required for disparity selectivity.
关键期的经历塑造了新皮层内的神经回路，导致感觉神经元功能反应的变化。视觉关键期的单眼剥夺（MD）会使初级视皮层（V1）的眼优势，即优势眼，向睁开的眼睛偏移，并扰乱视力的正常发育。在食肉动物和灵长类动物中，MD还会扰乱双眼视差选择性的出现，这是一种整合眼部输入产生的线索。这种扰乱可能是剥夺后仅由睁开的眼睛驱动的神经元增加的结果，也可能是眼部输入汇聚不匹配的结果。为了区分这些可能性，我们测量了MD后雄性和雌性小鼠V1神经元的眼优势（OD）和视差选择性。正常小鼠V1神经元由对侧眼输入主导，对侧眼剥夺会使小鼠V1神经元的双眼反应更加平衡。通过OD测定，这种向双眼性的转变降低了视差敏感性。MD并没有改变双眼性的初始成熟过程，因为MD前的视差选择性与正常成熟动物没有区别。视差调谐的降低在双眼和同侧偏向的神经元中最为明显，这些神经元是OD变化最大的群体。与视差选择性的下降相一致，我们观察到MD后同侧眼的空间频率选择性向更低频率偏移。这些结果表明，MD期间出现了新的突触输入，扰乱了视差选择性的表征。我们证明，发育关键期的单眼剥夺会损害小鼠初级视皮层的双眼整合。尽管神经元的双眼性程度有所增加，但这种损害仍然发生。我们进一步证明，我们的剥夺并没有损害视差选择性的成熟。视差选择性在单眼剥夺之前就已经达到了成熟水平。视差调谐的丧失主要在由睁开的眼睛主导的神经元中观察到，这表明改变的输入与视差敏感性的丧失之间存在联系。这些结果表明，剥夺后的新输入可能无法维持视差选择性所需的两只眼睛输入之间精确的空间关系。
