Knudsen E I, Esterly S D, du Lac S
Department of Neurobiology, Stanford University School of Medicine, California 94305-5401.
J Neurosci. 1991 Jun;11(6):1727-47. doi: 10.1523/JNEUROSCI.11-06-01727.1991.
Vision during early life plays an important role in calibrating sound localization behavior. This study investigates the effects of visual deprivation on sound localization and on the neural representation of auditory space. Nine barn owls were raised with eyelids sutured closed; one owl was congenitally anophthalmic. Data from these birds were compared with data from owls raised with normal visual experience. Sound localization behavior was significantly less precise in blind-reared owls than in normal owls. The scatter of localization errors was particularly large in elevation, though it was abnormally large in both dimensions. However, there was no systematic bias to the localization errors measured over a range of source locations. This indicates that the representation of auditory space is degraded in some way for blind-reared owls, but on average is properly calibrated. The spatial tuning of auditory neurons in the optic tectum was studied in seven of the blind-reared owls to assess the effects of early visual deprivation on the neural representation of auditory space. In normal owls, units in the optic tectum are sharply tuned for sound source location and are organized systematically according to the locations of their receptive fields to form a map of auditory space. In blind-reared owls, the following auditory properties were abnormal: (1) auditory tuning for source elevation was abnormally broad, (2) the progression of the azimuths and elevations of auditory receptive fields across the tectum was erratic, and (3) in five of the seven owls, the auditory representation of elevation was systematically stretched, and in the two others large portions of the representation of elevation were flipped upside down. The following unit properties were apparently unaffected by blind rearing: (1) the sharpness of tuning for sound source azimuth, (2) the orientation of the auditory representation of azimuth, and (3) the mutual alignment of the auditory and visual receptive fields in the region of the tectum representing the area of space directly in front of the animal. The data demonstrate that the brain is capable of generating an auditory map of space without vision, but that the normal precision and topography of the map depend on visual experience. The space map results from the tuning of tectal units for interaural intensity differences (IIDs) and interaural time differences (ITDs; Olsen et al., 1989).(ABSTRACT TRUNCATED AT 400 WORDS)
早期生活中的视觉在校准声音定位行为方面起着重要作用。本研究调查了视觉剥夺对声音定位以及听觉空间神经表征的影响。九只仓鸮在眼睑缝合闭合的情况下饲养；一只猫头鹰先天性无眼。将这些鸟类的数据与具有正常视觉体验的猫头鹰的数据进行比较。与正常猫头鹰相比，在视觉剥夺环境中饲养的猫头鹰的声音定位行为明显不那么精确。定位误差的离散度在仰角方向上特别大，尽管在两个维度上都异常大。然而，在一系列声源位置测量的定位误差没有系统偏差。这表明对于在视觉剥夺环境中饲养的猫头鹰，听觉空间的表征在某种程度上有所退化，但平均而言校准是正确的。在七只视觉剥夺环境中饲养的猫头鹰中研究了视顶盖中听觉神经元的空间调谐，以评估早期视觉剥夺对听觉空间神经表征的影响。在正常猫头鹰中，视顶盖中的神经元对声源位置有敏锐的调谐，并根据其感受野的位置系统地组织起来，形成听觉空间图谱。在视觉剥夺环境中饲养的猫头鹰中，以下听觉特性异常：(1) 对声源仰角的听觉调谐异常宽泛，(2) 听觉感受野在视顶盖上的方位和仰角的进展不稳定，(3) 在七只猫头鹰中的五只中，仰角的听觉表征被系统地拉伸，在另外两只中，仰角表征的大部分上下颠倒。以下单元特性显然不受视觉剥夺饲养的影响：(1) 对声源方位的调谐锐度，(2) 方位听觉表征的方向，(3) 在视顶盖代表动物正前方空间区域中听觉和视觉感受野的相互对齐。数据表明，大脑能够在没有视觉的情况下生成听觉空间图谱，但图谱的正常精度和地形学依赖于视觉体验。空间图谱是由视顶盖单元对耳间强度差 (IID) 和耳间时间差 (ITD；Olsen等人，1989年) 的调谐产生的。(摘要截断于400字)
