Tan U
Atatürk University, Medical Faculty, Institute of Physiology, Erzurum, Turkey.
Int J Neurosci. 1989 Oct;48(3-4):255-69. doi: 10.3109/00207458909002169.
The spinal motor asymmetry was studied in left-handers. Hand preference was assessed by Geschwind scores (GS), and hand skill by peg moving task, the reflex responses were recorded from the long flexor muscle of the thumb. The H-reflex could be elicited by averaging during cortico-spinal facilitation (voluntary isometric force). The Cattell's Culture Fair Intelligence Test was used to assess the individual differences in mental abilities. H-reflexes were found to be significantly larger on the left than the right side. The amplitude of H-reflex increased linearly with force applied to transducer by the thumb. This facilitation was more pronounced for the left than the right reflexes. Removal of the visual visual input caused facilitation in H-reflex (supraspinal disinhibition). Post-activation potentiation was also observed in H-reflex. There was a positive linear correlation between the degree of left-hand preference (-GSs) and left-hand skill. The correlation for the right-hand skill was not significant. There was a linear correlation between the degree of left-hand preference and the right minus left hand skill. There was an inverse correlation between left-hand skill and H-reflex from left. The correlation for the right side did not reach the 5% significance level. The force-reflex relation did not show any significant change to IQ for the right H-reflex. The left H-reflexes were significantly larger in subjects with high IQ than those with low IQ. The regression line and its slope for the force-reflex relation on the left was found to be higher in subjects with high IQ than those with low IQs. There was a positive linear relationship between IQ and H reflex from left. The correlation for the right side was not as pronounced as that for the left side. The left minus right H reflex was also positive linearly correlated with IQ. These results provide further evidence for the psycho-motor hypothesis (Tan. 1988b) as well as the spinal motor asymmetry to handedness. It was suggested that lateralization of cognitive and motor functions would be essential to create subjects with high psychomotor capacity.
对左利手者的脊髓运动不对称性进行了研究。通过盖什温德分数（GS）评估手偏好，通过插栓移动任务评估手技能，从拇指长屈肌记录反射反应。在皮质脊髓易化（自愿等长力）期间通过平均法诱发H反射。使用卡特尔文化公平智力测验评估心理能力的个体差异。发现左侧的H反射明显大于右侧。H反射的幅度随着拇指施加在换能器上的力呈线性增加。这种易化在左侧反射中比右侧更明显。去除视觉输入会导致H反射易化（脊髓上抑制解除）。在H反射中也观察到激活后增强。左手偏好程度（-GSs）与左手技能之间存在正线性相关。右手技能的相关性不显著。左手偏好程度与右手减去左手技能之间存在线性相关。左手技能与左侧H反射之间存在负相关。右侧的相关性未达到5%的显著性水平。右侧H反射的力-反射关系对智商未显示出任何显著变化。高智商受试者的左侧H反射明显大于低智商受试者。发现高智商受试者左侧力-反射关系的回归线及其斜率高于低智商受试者。智商与左侧H反射之间存在正线性关系。右侧的相关性不如左侧明显。左侧减去右侧H反射也与智商呈正线性相关。这些结果为心理运动假说（Tan，1988b）以及脊髓运动与利手的不对称性提供了进一步的证据。有人提出，认知和运动功能的侧化对于创造具有高心理运动能力的个体至关重要。
