Neuroanatomical Correlated of Cognitive Control

人类的大脑大约比我们体重的一个物种应该大三倍。在……里面 此外，大脑的进化并不是一致的，在哺乳动物中，特别是在灵长类动物中，不同物种中选择了不同的皮质和亚皮质区域(T.W.Deacon，1997；Finlay&Darlington，1995；J.K.Rilling，2006；Semendeferi&Damasio，2000)。例如，在灵长类动物中，一些人认为额叶和颞叶相对于其他脑叶存在不同的扩张，这些变化可能反映了与复杂认知相关的大脑区域中皮质发育的特定选择，包括语言(T.Deacon，2004；J.K.Rling&Sig man，2002；Semendeferi，Armstrong，Schleicher，Zilles，&Van Hoesen，2001；Semendeferi，Lu，Schenker，&Damasio，2002)。 神经科学领域的主要挑战之一是理解 大脑的进化与新出现的行为和认知过程有关，这些过程定义了人类相对于其他灵长类动物的物种。与这一挑战相关的是寻求了解遗传和非遗传因素在大脑发育和进化中与特定感兴趣行为相关的作用。拟议研究的主要重点是开始处理灵长类执行功能在个体背景下的进化与大脑系统发育变化之间的关系，特别是前额叶皮质和相关的纹状体和边缘系统结构。人类认知神经科学中的“执行功能”或“认知控制”一词反映了对许多动机、情绪和注意系统施加元控制或决策过程的能力。认知控制的概念意味着，存在自上而下的系统，它们对更多由生物驱动的动机或情绪状态施加抑制控制。这种自上而下的系统强调了关闭或抑制冲动行为的能力，或者提供了以牺牲眼前利益为代价来预见未来回报的能力(有时被称为延迟满足感)(E.K.Miller，2000；E.K Miller，2000)，一些人认为这种能力是非常高级的，可能是人类独有的(Roberts，2002)。 这一系统的一个启发式概念被称为延迟满足的“热-冷”系统(Metcalfe&Mischel，1999)。在这个模型中，有热的“情绪围棋系统”和冷的“知道”系统，其特征是情绪中立、沉思，以及自我调节和自我控制的位置。 因此，在古人类(可能还有类人族)进化过程中，大概有更大的 选择认知控制(冷静的系统)来控制“热”的情绪、冲动的系统。 从动机和情绪的角度来看，许多人认为，前额叶皮质、前扣带回和纹状体内的区域(特别是尾状回)在自我控制的能力中发挥着非常重要的作用，或者在对受试者的行为施加强大刺激控制的预先有效刺激的存在下，抑制特定类型的行为过程。例如，在人类中，随着前额叶、顶叶和纹状体的成熟和连通性的增加，延迟满足有显著的发育变化(Bunge&Wright，2007；Casey，Getz，&Galvan，2008)。 临床研究进一步支持前额叶皮质在认知或执行控制中的作用。前额叶皮质及相关的边缘系统和纹状体结构受损的个体被描述为刺激限制；即他们的行为被条件性地引起强烈反应的即时优先刺激捕获，他们无法超越这些冲动行为，并参与在随后的时间点导致奖励的行为(Bechara，Tranel，&Damasio，2000；E.K Miller，2000；Sax et al.，1999)。 可以说，执行功能紊乱最显著的临床表现之一是 被诊断为注意力缺陷多动障碍(ADHD)的患者。尽管行政职能是 在人类神经心理学文献中，许多人认为大多数ADHD个体的中心行为问题是行为抑制的崩溃(Baird，Stevenson，&Williams，2000；R.A.Barkley，1997；R.A.Barkley，2001)，在行为上表现为自我控制能力差和冲动。在ADHD和非ADHD成人和儿童人群包括前额叶皮质、前扣带回和纹状体区域(尾状核和壳核)的比较中，执行功能的神经相关性有相当大的重叠。例如，对ADHD患者和对照组之间大脑结构差异的Meta分析表明，在前额叶皮质、小脑、穹隆压部和尾状核的体积和偏侧化方面存在显著差异(Casey等人，1997；Mostofsky，Cooper，Kates，Denckia，&Kaufmann，2002；Valera，Faraone， Murray和Seidman，2007)。研究表明，右侧额叶皮质的损伤与工作记忆和反应抑制的缺陷有关，这一结果在患有ADHD的成年人中也观察到了类似的模式(Clark等人，2007年)。值得注意的是，ADHD在男性中明显比女性更普遍，最近一项关于延迟满足的研究综述表明，女性明显好于男性(Silverman，2003)。

The human brain is roughly three times larger than it should be for a species of our body weight. In addition, the evolution of the brain has not been uniform, with distinct cortical and sub-cortical regions being selected for in different species among mammals, and specifically within primates (T. W. Deacon, 1997; Finlay & Darlington, 1995; J. K. Rilling, 2006; Semendeferi & Damasio, 2000). For example, in primates, some have suggested there has been differential expansion of the frontal and temporal lobes relative to the other lobes and that these changes might reflect specific selection for cortical development in brain regions associated with complex cognition, including language (T. Deacon, 2004; J. K. Rilling & Seligman, 2002; Semendeferi, Armstrong, Schleicher, Zilles, & Van Hoesen, 2001; Semendeferi, Lu, Schenker, & Damasio, 2002). One of the main challenges in the field of neuroscience is to understand the development and evolution of the brain in relation to emergent behavioral and cognitive processes that define the human species relative to other primates. Related to this challenge is the quest to understand the role of genetic and non-genetic factors on the development and evolution of the brain in relation to specific behaviors of interest. The main focus of the proposed studies is to begin to address the relationship between the evolution of executive functions, broadly defined, in primates in the context of individual and phylogenetic changes in the brain, notably the prefrontal cortex and associated striatal and limbic system structures. The term "executive function" or "cognitive control" in human cognitive neuroscience reflects the ability to exert meta-control or decision making processes over a number of motivational, emotional and attentional systems. The notion of cognitive control implies that there are top-down systems that exert inhibitory control over more biologically driven motivational or emotional states. This top-down system underlies the ability to shut down or inhibit impulsive behaviors or provide for the ability to foresee reward in the future at the expense of immediate gains (sometimes referred to as delayed gratification) (E. K. Miller, 2000; E. K Miller, 2000), abilities some have suggested are highly advanced and possibly uniquely human (Roberts, 2002). One heuristic conceptualization of this system has been referred to as the "hot-cool" system of delayed gratification (Metcalfe & Mischel, 1999). In this model, there is the hot "emotional go system" and the cool "know" system characterized as emotionally neutral, contemplative and the seat of self regulation and selfcontrol. Accordingly, during hominin (and possibly hominoid) evolution, presumably there has been greater selection for cognitive control (the cool system) over the "hot" emotional, impulsive system. From a motivational and emotional standpoint, many have suggested that the prefrontal cortex, anterior cingulate and regions within the striatum (notably the caudate) play very important roles in the ability to exert self-control, or to suppress specific kinds of behavioral processes in the presence of pre-potent stimuli that exert strong stimulus control over the subjects' behavior. For example, in humans, there are significant developmental changes in delayed gratification that correspond to increasing maturation and connectivity in the prefrontal cortex, parietal lobe and striatum (Bunge & Wright, 2007; Casey, Getz, & Galvan, 2008). Clinical studies further support the role of prefrontal cortex in cognitive or executive control. Individuals with lesions in prefrontal cortex and associated limbic system and striatum structures have been described as stimulus bound; that is, their behavior is captured by immediate prepotent stimuli that reflexively elicit strong reactions and they are unable to override these impulsive behaviors and engage in behaviors that result in reward at later points in time (Bechara, Tranel, & Damasio, 2000; E. K Miller, 2000; Sax et al., 1999). Arguably, one of the most pronounced clinical manifestations of disrupted executive functions are patients diagnosed as attention-deficit hyperactivity disorder (ADHD). Though executive functions are broadly defined in the human neuropsychological literature, many have argued that the central behavioral problem of most ADHD individuals is a breakdown in behavioral inhibition (Baird, Stevenson, & Williams, 2000; R. A. Barkley, 1997; R. A. Barkley, 2001) that expresses itself behaviorally as poor self-control and impulsivity. There is considerable overlap in the neural correlates of executive function and in the comparison of ADHD and non-ADHD adult and child populations including prefrontal cortex, anterior cingulate and region of the striatum (caudate and putamen). For instance, meta-analyses of studies of structural brain differences between ADHD individuals and controls have revealed significant differences in the volume and lateralization of the prefrontal cortex, cerebellum, splenium of the corpus callosum and caudate (Casey et al., 1997; Mostofsky, Cooper, Kates, Denckia, & Kaufmann, 2002; Valera, Faraone, Murray, & Seidman, 2007). It has been shown that damage to the right frontal cortex is associated with deficits in working memory as well as response inhibition, a pattern of results similarly observed in adults with ADHD (Clark et al., 2007). It is of note that ADHD is significantly more prevalent in males than females and a recent review of the studies on delay of gratification showed that women were significantly better than men (Silverman, 2003).