Study of glial cell function in brain synaptic networks

大脑是迄今为止人体最复杂的器官，也是大自然设计的最神秘的机器之一。除了控制大多数重要功能外，中枢神经系统（CNS）还负责生物体产生的所有输出。这些输出通常来自组成它的细胞的正常功能，特别是神经元细胞。这些细胞具有活跃的特性，对大脑的活动有反应。有不同类型的神经细胞，特别是那些向远处的目标传递神经元信息的细胞和那些创建局部网络来调节给定区域所有神经细胞活动的细胞。将信息传递到远处目标的细胞被认为是兴奋的，因为它们会促进其他神经细胞的活动。调节神经细胞网络的细胞通常被认为是抑制细胞，因为它们的作用是降低其他神经细胞的活性。

The brain is by far the most complex organ of the human body and one of the most mysterious machines ever designed by nature. Besides controlling most vital functions, the central nervous system (CNS) is also responsible for every output produced by the organism. These outputs normally result from proper functioning of the cells with which it is composed, in particular the neuronal cells. These cells have the particularity of being active and responsive to the activity in the brain. There are different types of nerve cells, in particular those that convey the neuronal information towards a distant target and those that create a local network to regulate the activity all nerve cells of a given area. The cells that carry the information to a distant target are said to be excitatory as they will facilitate the activity of other nerve cells. The cells that regulate the network of nerve cells are often identified as inhibitory cells, as their role is to reduce the activity of other nerve cells. Nerve cells are responsible for the communication in the nervous system releasing chemical substance called neurotransmitters at specialised structures identified as synapses. A very important feature of the nervous system and its components is that they express a propensity to change with previous brain activity, providing the cellular basis for learning and memory formation. This process involves a fine interplay between the excitatory and inhibitory neurons and synapses and any modulation that affects neuronal activity will modulate the transfer of neuronal information. In addition to nerve cells, the other main cellular elements in the brain are glial cells, in particular one type of glial cells known as astrocytes owing to their stellar shape. These glial cells have long been known as the support cells of the brain, providing nutrients and energy to the nerve cells, while keeping the proper environment for the nerve cells functions. However, a number of studies, including ours, have revealed that glial cells too, are excitable, as they detect and understand neuronal communication. Importantly, as a result of this change in their activity, glial cells modify neuronal excitability and the learning process. Hence, glial cells influence directly the quality of neuronal communication and the propensity of nerve cells to learn and form memory. However, this crucial role of glial cells has been unraveled only for excitatory neurons and their communication, and the impact on the very important inhibitory neuronal network has never been addressed. Hence, the goal of this work is to determine the mechanisms by which glial cells influence inhibitory neurons and how this regulation alters the function of the network of nerve cells and its ability to create learning events. As a whole, this work would allow us to unravel for the first time the ability of glial cells to integrate complex network of neurons. It is becoming clear that a full understanding of the brain and the diseases that affects its functions will never be understood unless the complex interactions between excitatory, inhibitory and glial cells are considered.