Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey
Transient and permanent deficits in motion perception after lesions of cortical areas MT and MST in the macaque monkey
复制标题
DOI：
10.1093/cercor/9.1.90
复制
发表时间：
1999-01-01
期刊：
影响因子：
3.7
通讯作者：
Pasternak, T
中科院分区：
文献类型：
--
作者：
Rudolph, K;Pasternak, T
我们检查了纹外区MT和MST病变产生的运动缺陷的性质和选择性。在两只猕猴的左侧视野中注射鹅膏藤酸，造成损伤。猴子辨别出两个刺激方向或方向不同的刺激。通过在完整或受损视野中放置栅格和随机点来测量阈值来评估方向和方向辨别能力。在行为测试开始时，我们发现所有类型的运动刺激的阈值都有明显的运动特异性缺陷，包括用移动栅格测量的对比度阈值和信噪比阈值的显著升高，以及用随机点刺激测量的方向范围阈值和运动连贯性的缺陷。此外，在较小的空间位移(即步长)时，方向辨别的精度降低，这表明剩余定向机构的空间尺度增加。随着行为训练的进行，所有运动刺激的阈值随后都有所改善，而这些改善只有在受损视野中进行广泛的行为测试时才会发生。对于没有被噪音掩盖的刺激，这些改善尤其明显。另一方面，尽管进行了广泛的行为训练，但从嘈杂刺激中提取动作的能力和辨别方向的准确性方面的缺陷仍然存在。这些结果证明了MT区和MST区对于运动方向知觉的重要性，特别是在存在噪声的情况下。此外，它们还为行为训练对皮质损伤后功能恢复的重要性提供了证据。这些数据也有力地支持了运动处理的MT和MST区域的功能专门化的想法。
We examined the nature and the selectivity of the motion deficits produced by lesions of extrastriate areas MT and MST. Lesions were made by injecting ibotenic acid into the representation of the left visual field in two macaque monkeys. The monkeys discriminated two stimuli that differed either in stimulus direction or orientation. Direction and orientation discrimination were assessed by measuring thresholds with gratings and random-dots placed in the intact or lesioned visual fields. At the start of behavioral testing, we found pronounced, motion-specific deficits in thresholds for all types of moving stimuli, including pronounced elevations in contrast thresholds and in signal-to-noise thresholds measured with moving gratings, as well as deficits in direction range thresholds and motion coherence measured with random-dot stimuli. In addition, the accuracy of direction discrimination was reduced at smaller spatial displacements (i.e. step sizes), suggesting an increase in spatial scale of the residual directional mechanism. Subsequent improvements in thresholds were seen with all motion stimuli, as behavioral training progressed, and these improvements occurred only with extensive behavioral testing in the lesioned visual field. These improvements were particularly pronounced for stimuli not masked by noise. On the other hand, deficits in the ability to extract motion from noisy stimuli and in the accuracy of direction discrimination persisted despite extensive behavioral training. These results demonstrate the importance of areas MT and MST for the perception of motion direction, particularly in the presence of noise. In addition, they provide evidence for the importance of behavioral training for functional recovery after cortical lesions. The data also strongly support the idea of functional specialization of areas MT and MST for motion processing.