探索大脑的奥秘已经成为系统科学的重要研究领域，而理解大脑眶额叶的性质与功能是其中的一个关键主题。大脑眶额叶是执行认知功能的重要脑区。眶额叶有着极为丰富的脑区内及脑区间的连接投射关系，其通过与嗅觉、味觉等感觉皮层的双向投射接受到众多感觉信息，并且与杏仁核、海马、前扣带回、纹状体等脑区也有着复杂的连接关系。眶额叶区域可以对于决策行为背后的价值、抽象的任务状态等信息进行表征，并且通过在各个环路中的投射关系，广泛地参与到动物的学习、决策、情绪过程中。眶额叶的功能失调与许多脑疾病，如强迫症、抑郁症等有着密切关系，将眶额叶作为治疗靶点，对于这些疾病的干预也有着积极的作用。大脑眶额叶的研究，对于理解认知过程、挖掘认知行为的神经机制，并基于此开发脑疾病的诊断和干预方法都有着重要的意义。
从系统科学的研究视角来考察，大脑是一个天然的，具有着多元性、耦合性、层次性、涌现性的复杂系统。大脑眶额叶一方面是这一复杂系统的重要组成，另一方面其本身也是其他脑区有着多尺度交互关系的复杂系统。系统科学所强调的系统的整体性，系统的演化性以及系统复杂特征的涌现性，也为大脑眶额叶的研究提供了新视角。本文基于系统科学的视角，通过脑电信号处理、数据分析技术以及计算模型等研究方法，从宏观的脑区连接模式、具体的认知功能、以及功能背后的底层交互机制三个方面，对于眶额叶进行探究。
本文的具体研究内容如下：
1. 针对于眶额叶的连接模式，本研究使用了皮层–皮层诱发电位（Cortico-cortical Evoked Potential，简称 CCEP）对于眶额叶区域与全脑各脑区宏观的连接关系进行探究。首先，对于有眶额叶植入电极的癫痫被试进行了标准的 CCEP 电刺激，并将不同被试的 CCEP 连接矩阵进行整合，构建了以眶额叶为中心的 CCEP 概率连接矩阵。进一步，通过聚类分析以及表征相似性分析，对眶额叶 CCEP 连接关系所具有的连接模式进行探究，观察到内、外侧眶额叶 CCEP 连接模式的差异化特征。研究中所涉及的不同脑区可以按照内、外侧眶额叶差异性的 CCEP 概率连接，划分为内、外侧眶额叶的特异性连接区域。这种内、外侧眶额叶的连接差异性同样也在眶额叶癫痫的传播过程中得到了体现。
2. 针对于眶额叶的认知功能，本研究通过癫痫被试的侵入式脑电图（Intracranial Electroencepholography，简称 iEEG），分析了自由空间的空间位置记忆任务中，眶额叶的功能以及功能连接特性。首先，借助癫痫被试在任务中所记录到的眶额叶 iEEG 信号，发现了眶额叶区域 Theta 频段对于物体位置信息以及反馈信息的表征。通过行为表现与区激活的相关性分析，发现了内、外侧眶额叶区域 Theta 频段信号对于空间状态以及反馈价值表征的差异性特征，内侧眶额叶会倾向于对反馈价值进行表征，外侧眶额叶会出现无反馈表征。进一步，通过脑区间信号的相干性分析，发现了眶额叶与海马脑区 Theta 频段的同步程度会随着学习过程而提高，并且内侧眶额叶的学习效应侧重于反馈过程，而外侧眶额叶侧重于空间位置提取过程。最后，通过方向性分析，揭示了学习过程中，从眶额叶到海马的自上而下的功能调制。
3. 针对眶额叶功能的底层交互机制，本研究基于先前研究所发现的内、外侧眶额叶功能特性及其连接模式，构建了以眶额叶为核心的通用学习决策模型。模型中的内侧眶额叶参考了价值表征，外侧眶额叶则借鉴了吸引子网络并对于状态关系进行表征。模型会通过状态、价值的计算完成决策过程，并通过行为的反馈结果对于表征进行更新。此模型具有对于不同任务的通用性，对于真实空间任务，模型具有对空间位置的学习能力；对于抽象空间任务，模型具有对序列决策任务的学习能力。模型具有涌现性，其通过简洁的功能模块与更新规则设置，展现出复杂、动态环境下的路径规划能力以及对于变化规则的自适应能力。进一步，通过损伤实验的模拟，验证了模型所模拟的功能失调与真实的损伤实验结果有着很强的一致性，这表明了模型是对于眶额叶认知功能底层机制较为合理的抽象。
本文的研究方法与结果，加深了我们对于大脑眶额叶区域结构、功能以及认知过程的理解，也为系统科学视角下的脑科学的研究提供了新的参考，具有重要的理论意义；同时，对于眶额叶及其相关功能环路的探究，也为众多脑疾病的诊疗和干预提供了新的思路和潜在的手段，具有广泛的应用前景。

Exploring the mysteries of the brain has become an important area of  systems science, and understanding the nature and function of the orbitofrontal cortex (OFC) is a key theme.The OFC is an important brain region for cognitive function. The OFC has a very rich connection and projection relationship between different brain regions. It receives a lot of sensory information through bidirectional projections with sensory cortex such as smell and taste, and it also has complex connections with amygdala, hippocampus, and anterior cingulate, etc.OFC can represent the value of decision-making behavior, abstract task state and other information, and it is widely involved in animal learning, decision-making, and emotion through the projection relationship in cognitive loop.The dysfunction of OFC is closely related to many brain diseases, such as obsessive-compulsive disorder and depression. Using the OFC as a therapeutic target also has a positive effect on the intervention of these diseases. The study of OFC is of great significance for understanding the cognitive process, mining the neural mechanism of cognitive behavior, and developing diagnosis and intervention methods for brain diseases.
From the perspective of systems science research, the brain is a natural complex system with diversity, coupling, hierarchy, and emergence. The OFC, on the one hand is an important component of the complex system, brain; on the other hand, it is also a complex system with multi-scale interactions with other brain regions. The integrity of the system, the evolution of the system and the emergence of the complex characteristics of the system, which are emphasized by systems science, also provide a new perspective for the study of the OFC of the brain. Based on the perspective of systems science, this paper explores the OFC from three aspects: macroscopic connection pattern, specific cognitive functions, and underlying interaction mechanism through electroencepholography signal processing, data analysis techniques, and computational models. 
The specific research contents of this paper are as follows:
1. In view of connection pattern of the OFC, this study uses the cortico-cortical evoked potential (CCEP) to explore the macroscopic connection between the OFC and the brain regions of the whole brain. First, standard CCEP electrical stimulation was performed on epileptic subjects with implanted electrodes in the OFC, and the CCEP connection matrix of different subjects was integrated to construct a CCEP probability connection matrix centered on the OFC.Furthermore, cluster analysis and representation similarity analysis were used to explore the connectivity pattern of CCEP connections in the OFC, and found the differential characteristics of the medial and lateral orbitofrontal CCEP connectivity pattern. The different brain regions involved in the study can be divided into specific connection regions of the medial and lateral OFC through the differential CCEP probability connection between the medial and lateral OFC. This difference in the connectivity between the medial and lateral OFC is also reflected in the spread of orbitofrontal epilepsy.
2. In view of cognitive function for the OFC,  the function and functional connectivity features of the OFC in the free-space spatial location memory task were analyzed through the invasive electroencephalography (iEEG) signals of the epilepsy subjects in this study. First, by means of the orbitofrontal iEEG signals recorded in the epilepsy subjects in the free-space memory task, we found that the Theta frequency band in the OFC region represents object position information and reward information. Through the correlation analysis between behavioral performance and brain activation, this study found that the Theta band signals in the medial and lateral OFC have different characteristics for spatial state and reward value representation. The medial OFC tends to represent reward value. The lateral OFC tends to have non-reward representation.Further, through the coherence of the inter-brain signals, it was found that the degree of synchronization of the Theta frequency band between the OFC and the hippocampal can increase with the learning process, and the learning effect of the medial OFC focuses on the reward process, while the lateral OFC focuses on the spatial location extraction process. Finally, directional analysis of EEG signals revealed top-down functional modulations from the OFC to the hippocampus during learning.
3. In view of underlying interaction mechanisms for OFC function,based on the functional characteristics and the connection of the medial and lateral OFC in previous studies, a general learning decision-making model with the OFC as the core was constructed in this study. The medial OFC in the model refers to value representations, while the lateral OFC refers to attractor networks and constructs representations of state relations. The model will complete the decision-making process through the calculation of state and value, and update the representation through the reward of behavior.This model has the characteristics of generality for different tasks. For real space tasks, the model has the ability to learn spatial positions; for abstract space tasks, the model has the ability to learn sequence decision tasks. The model has emergence, and it shows the ability of path planning in complex environments and the ability to adapt to changing rules through simple function modules and update rule settings.Furthermore, through the experimental simulation of OFC damage, it was verified that the dysfunction simulated by the model had a strong consistency with the real OFC damage results, which indicated that the model was a good abstraction of the underlying mechanism of the OFC cognitive function.
The research methods and results of this paper have deepened our understanding of the structure and function of the OFC and the cognitive process of the brain, and also provided a new reference for the research of brain science from the perspective of systems science,  has important theoretical significance. At the same time, the exploration of the OFC and its related functional circuits also provides new ideas and potential means for the diagnosis, treatment and intervention of many brain diseases, and has broad application prospects.