Assessing the heritability of attentional networks

BACKGROUND: Current efforts to study the genetics of higher functions have been lacking appropriate phenotypes to describe cognition. One of the problems is that many cognitive concepts for which there is a single word (e.g. attention) have been shown to be related to several anatomical networks. Recently we have developed an Attention Network Test (ANT) that provides a separate measure for each of three anatomically defined attention networks. In this small scale study, we ran 26 pairs of MZ and DZ twins in an effort to determine if any of these networks show sufficient evidence of heritability to warrant further exploration of their genetic basis. RESULTS: The efficiency of the executive attention network, that mediates stimulus and response conflict, shows sufficient heritability to warrant further study. Alerting and overall reaction time show some evidence for heritability and in our study the orienting network shows no evidence of heritability. CONCLUSIONS: These results suggest that genetic variation contributes to normal individual differences in higher order executive attention involving dopamine rich frontal areas including the anterior cingulate. At least the executive portion of the ANT may serve as a valid endophenotype for larger twin studies and subsequent molecular genetic analysis in normal subject populations.

研究背景：当前针对高级认知功能遗传学的研究，始终缺乏适配认知活动描述的标准化表型。其中一项核心困境在于，诸多仅以单一词汇指代的认知概念（如注意），已被证实与多个解剖学层面的神经网络存在关联。本团队近期开发了注意网络测试（Attention Network Test, ANT），可分别量化三个经解剖学定义的注意子网络的功能表现。本项小规模研究共纳入26对同卵双生子（monozygotic twins, MZ）与异卵双生子（dizygotic twins, DZ），旨在探明上述任一注意网络是否具备足够的遗传力证据，以支撑对其遗传基础的后续探索研究。

研究结果：负责调控刺激与反应冲突的执行注意网络，其运作效率具备显著遗传力，值得开展进一步深入研究。警觉性功能与整体反应时仅表现出微弱的遗传力相关证据，而本研究中定向注意网络未观测到任何遗传力相关特征。

研究结论：本研究结果表明，遗传变异是导致正常个体在高阶执行注意功能上存在个体差异的重要因素，该功能涉及包含前扣带回皮层在内的富含多巴胺的额叶脑区。至少，注意网络测试的执行功能子模块，可作为开展大规模双生子研究以及后续正常受试人群分子遗传学分析的可靠内表型（endophenotype）。