Brain Mechanisms and Cognitive Functions | 大脑机制与认知功能

📚 Brain Mechanisms and Cognitive Functions | 大脑机制与认知功能

In the study of psychology, the relationship between the brain and cognitive function is fundamental. Cognitive psychology examines how mental processes such as perception, memory, language, and reasoning arise from the biological machinery of the brain. Understanding these mechanisms is essential for exam success in psychology.

在心理学研究中，大脑与认知功能之间的关系是基础性的。认知心理学研究感知、记忆、语言和推理等心理过程如何源于大脑这一生物学机器。理解这些机制是心理学考试取得好成绩的关键。

1. Neurons and Neural Communication | 神经元与神经通讯

The neuron is the basic building block of the nervous system. A typical neuron consists of dendrites, a cell body (soma), an axon, and terminal buttons. Dendrites receive incoming signals, the axon conducts electrical impulses called action potentials, and terminal buttons release neurotransmitters into the synapse. Neurons do not physically touch; they communicate across a microscopic gap known as the synaptic cleft.

神经元是神经系统的基本构成单位。典型神经元由树突、细胞体（胞体）、轴突和终扣组成。树突接收传入信号，轴突传导称为动作电位的电冲动，终扣向突触释放神经递质。神经元之间并不直接接触，而是通过称为突触间隙的微小间隙进行通讯。

Communication between neurons occurs through synaptic transmission. When an action potential reaches the terminal button, synaptic vesicles fuse with the presynaptic membrane and release neurotransmitters into the cleft. These molecules then bind to receptors on the postsynaptic membrane, either exciting or inhibiting the receiving neuron. This all-or-nothing process is fundamental to every thought, feeling, and behaviour.

神经元之间通过突触传递进行通讯。当动作电位到达终扣时，突触囊泡与前膜融合，向突触间隙释放神经递质。这些分子随后与突触后膜上的受体结合，兴奋或抑制接收神经元。这种”全或无”的过程是每一个想法、情感和行为的生理基础。

• Excitatory postsynaptic potentials (EPSPs) increase the likelihood of neuronal firing.
• 兴奋性突触后电位（EPSP）增加神经元放电的可能性。
• Inhibitory postsynaptic potentials (IPSPs) decrease the likelihood of neuronal firing.
• 抑制性突触后电位（IPSP）降低神经元放电的可能性。
• Summation of EPSPs and IPSPs determines whether an action potential is triggered.
• EPSP和IPSP的总和决定是否触发动作电位。

2. The Brainstem and Basic Life Functions | 脑干与基本生命功能

The brainstem, which includes the medulla oblongata, pons, and midbrain, sits at the base of the brain and connects to the spinal cord. The medulla controls vital reflexes such as breathing, heart rate, and blood pressure. The pons is involved in sleep regulation and arousal, while the midbrain contributes to visual and auditory reflexes. Without the brainstem, even the most sophisticated cognitive processes would be impossible because basic survival functions would fail.

脑干位于大脑底部并与脊髓相连，包括延髓、脑桥和中脑。延髓控制呼吸、心率和血压等重要反射；脑桥参与睡眠调节与唤醒；中脑则参与视觉与听觉反射。没有脑干，即使是最复杂的认知过程也不可能实现，因为基本生存功能将停止运作。

The reticular activating system (RAS), a network of neurons running through the brainstem, plays a central role in wakefulness and attention. Damage to the brainstem can result in coma or death, illustrating its fundamental importance for survival. In clinical cases, brainstem strokes often produce dramatic impairment of consciousness, confirming the region’s role in maintaining alertness.

网状激活系统（RAS）是贯穿脑干的神经元网络，在觉醒和注意中发挥核心作用。脑干损伤可导致昏迷甚至死亡，足见其对生存的根本重要性。在临床病例中，脑干卒中常导致意识的显著损害，证实了该区域在维持警觉状态中的作用。

3. The Cerebral Cortex and the Four Lobes | 大脑皮层与四个脑叶

The cerebral cortex is the outer layer of the brain, approximately 2-4 millimetres thick, and is responsible for higher cognitive functions. It is divided into four lobes: the frontal, parietal, temporal, and occipital lobes. Each lobe has specialised functions, but in reality they operate in an interconnected manner rather than in isolation.

大脑皮层是大脑外层，厚度约2-4毫米，负责高级认知功能。它分为四个脑叶：额叶、顶叶、颞叶和枕叶。每个脑叶具有特化功能，但实际上它们以相互连接的方式协同运作，而非孤立工作。

The frontal lobe contains the motor cortex, which controls voluntary movement, and the prefrontal cortex, which is associated with complex cognitive processes such as planning and social behaviour. Damage to the prefrontal cortex, as in the famous case of Phineas Gage, leads to personality changes and impaired judgement. Gage survived an iron rod piercing his skull, but his friends reported that he was ‘no longer Gage’ — a dramatic demonstration of the frontal lobe’s role in personality.

额叶包含控制随意运动的运动皮层，以及与计划和社会行为等复杂认知过程相关的前额叶皮层。如著名的菲尼亚斯·盖奇案例所示，前额叶皮层损伤会导致人格改变和判断力受损。盖奇在铁棍穿透颅骨后幸存下来，但他的朋友说他”不再是盖奇”——这是额叶在人格中作用的戏剧性证明。

4. The Limbic System | 边缘系统

The limbic system is a set of interconnected structures that regulates emotion, motivation, and memory. It includes the hippocampus, amygdala, hypothalamus, and thalamus. The term ‘limbic’ comes from the Latin word for border, reflecting that these structures form a border around the brainstem.

边缘系统是一组相互连接的结构，调节情绪、动机和记忆。它包括海马体、杏仁核、下丘脑和丘脑。”边缘”一词源于拉丁语”边界”之意，反映了这些结构环绕脑干形成一圈边界。

• The hippocampus is critical for the formation of new long-term memories.
• 海马体对形成新的长期记忆至关重要。
• The amygdala processes emotional significance, especially fear and threat.
• 杏仁核处理情绪意义，尤其是恐惧和威胁。
• The hypothalamus regulates homeostasis, hunger, thirst, and the endocrine system.
• 下丘脑调节体内稳态、饥饿、口渴和内分泌系统。
• The thalamus acts as a sensory relay station, routing information to the appropriate cortical areas.
• 丘脑充当感觉中转站，将信息路由到相应的大脑皮层区域。

5. Neurotransmitters and Behavior | 神经递质与行为

Neurotransmitters are chemical messengers that transmit signals across the synapse. Different neurotransmitters are associated with different psychological functions and disorders. A key exam point is the distinction between excitatory and inhibitory neurotransmitters and their physiological effects.

神经递质是跨突触传递信号的化学信使。不同的神经递质与不同的心理功能和精神障碍相关。一个关键的考点是兴奋性与抑制性神经递质的区别及其生理效应。