Rosen G D, Sherman G F, Mehler C, Emsbo K, Galaburda A M
Dyslexia Research Laboratory, Beth Israel Hospital, Boston, MA.
Int J Neurosci. 1989 Apr;45(3-4):247-54. doi: 10.3109/00207458908986237.
Cerebral asymmetry can be considered along two continua-one based on direction (i.e., left or right) and another based on magnitude (i.e., symmetrical or asymmetrical). The possibility exists that these continua operate independently (Collins, 1981). To examine this possibility, the brains of 21 New Zealand Black (NZB) mice with molecular layer neuronal ectopias and 19 NZB mice without ectopias were studied. In NZB mice without ectopias, the magnitude of cerebral cortical asymmetry was negatively correlated to total cerebral cortical volume, a finding previously reported in both humans (Galaburda, Corsiglia, Rosen and Sherman, 1987) and rats (Galaburda, Aboitiz, Rosen and Sherman, 1986). NZB mice with ectopias showed no such relationship. However, both groups of mice had a consistent rightward bias in the direction of neocortical asymmetry, replicating previous results in rodents (Diamond, Johnson and Ingham, 1975; Diamond, Dowling and Johnson, 1981; Kolb, Sutherland, Nonneman and Whishaw, 1982; Ward and Collins, 1985). This suggests that the mechanisms underlying the magnitude of cerebral cortical asymmetry differ from those underlying the direction of this asymmetry.
大脑不对称性可以沿着两个连续体来考量——一个基于方向（即左或右），另一个基于程度（即对称或不对称）。这两个连续体有可能独立运作（柯林斯，1981年）。为了检验这种可能性，对21只患有分子层神经元异位症的新西兰黑鼠（NZB）和19只没有异位症的NZB鼠的大脑进行了研究。在没有异位症的NZB鼠中，大脑皮质不对称程度与大脑皮质总体积呈负相关，这一发现先前在人类（加拉布尔达、科尔西利亚、罗森和谢尔曼，1987年）和大鼠（加拉布尔达、阿博伊蒂斯、罗森和谢尔曼，1986年）中均有报道。患有异位症的NZB鼠则没有这种关系。然而，两组小鼠在新皮质不对称方向上都有一致的向右偏向，这重复了先前在啮齿动物中的研究结果（戴蒙德、约翰逊和英厄姆，1975年；戴蒙德、道林和约翰逊，1981年；科尔布、萨瑟兰、诺内曼和惠肖，1982年；沃德和柯林斯，1985年）。这表明大脑皮质不对称程度背后的机制与这种不对称方向背后的机制不同。
