Aglioti S, Beltramello A, Tassinari G, Berlucchi G
Dipartimento di Scienze Neurologiche e della Visione, Universitá di Verona, Italy.
Neuropsychologia. 1998 Oct;36(10):1015-24. doi: 10.1016/s0028-3932(98)00055-4.
Symptoms of interhemispheric disconnection are typically much less severe in callosal agenesis than after surgical section of the corpus callosum. Sperry [Sperry, R. W., Plasticity of neural maturation. Developmental Biology, 1968, 2 (Suppl.), 306-327.] has attributed this difference to two interconnected factors: (1) the callosal section is usually performed after the brain has lost the maximal degree of functional plasticity associated with the early stages of development and (2) the removal of an already formed structure is more disruptive for functional brain organization than the failure of the same structure to develop. It has been suggested that functional compensation is less efficient if callosal agenesis is partial rather than complete [Dennis, M., Impaired sensory and motor differentiation with corpus callosum agenesis: A lack of callosal inhibition during ontogeny? Neuropsychologia, 1976, 14, 455-469.]. This suggestion is supported by the present findings of partial left-hand anomia, partial left-field alexia and poor tactile cross-localization in a subject with a congenital absence of the posterior part of the corpus callosum due to an arteriovenous malformation. In agreement with many previous studies, similar, though more severe, symptoms of interhemispheric disconnection were found in a subject with a complete section of the corpus callosum, but not in a subject with complete callosal agenesis. Praxic control of the left hand on verbal commands was severely deficient in the callosotomy subject, but it was normal in the subject with callosal hypogenesis. The lesser degree of compensation in partial compared to complete callosal agenesis may be explained by a reduced pressure to develop extracallosal means of interhemispheric communication, contingent on the partial existence of callosal connections, as well as by the later occurrence in development of the causes of callosal hypogenesis compared to those of total callosal agenesis.
大脑半球间分离的症状在胼胝体发育不全时通常比胼胝体手术切断后要轻得多。斯佩里[Sperry, R. W., 神经成熟的可塑性。《发育生物学》，1968年，2（增刊），306 - 327。]将这种差异归因于两个相互关联的因素：（1）胼胝体切断术通常是在大脑失去与发育早期相关的最大功能可塑性程度之后进行的；（2）去除一个已经形成的结构对大脑功能组织的破坏比相同结构未能发育更大。有人提出，如果胼胝体发育不全是部分性而非完全性的，功能补偿效率会更低[Dennis, M., 胼胝体发育不全导致的感觉和运动分化受损：个体发育过程中缺乏胼胝体抑制作用？《神经心理学》，1976年，14，455 - 469。]。一名因动静脉畸形导致先天性胼胝体后部缺失的受试者出现部分左手失命名、部分左视野失读症和触觉交叉定位不良的当前研究结果支持了这一观点。与许多先前的研究一致，在一名胼胝体完全切断的受试者中发现了类似但更严重的大脑半球间分离症状，而在一名胼胝体完全发育不全的受试者中未发现。在胼胝体切开术受试者中，根据言语指令对左手的运动控制严重不足，但在胼胝体发育不全的受试者中则正常。与完全性胼胝体发育不全相比，部分性胼胝体发育不全时补偿程度较低，可能是由于胼胝体连接部分存在时，发展大脑半球间非胼胝体沟通方式的压力减小，以及与完全性胼胝体发育不全相比，胼胝体发育不全原因在发育过程中出现得较晚。
