**Question:** Cells of cerebral cortex are all except

A. Neurons
B. Astrocytes
C. Microglia
D. Oligodendrocytes

**Core Concept:** The cerebral cortex is the outermost layer of the brain, primarily composed of neurons and plays a crucial role in higher cognitive functions. It is divided into four layers: I, II, III, and IV. Each layer is characterized by different types and arrangement of neurons.

**Why the Correct Answer is Right:** The correct answer "glial cells" refers to the non-neuronal cells that support and maintain the brain's neural network. Glial cells are essential for the proper functioning of the brain, but they do not contribute to the primary neural communication in the cerebral cortex.

**Why Each Wrong Option is Incorrect:**

A. Neurons: Neurons are the primary cells in the cerebral cortex, responsible for processing and transmitting information throughout the brain and body. They are the main component contributing to neural communication in this region.

B. Astrocytes: Astrocytes are glial cells that support and maintain the blood-brain barrier, regulate electrolyte balance, and provide structural support. They are not the primary cells responsible for neural communication in the cerebral cortex.

C. Microglia: Microglia are immune cells that monitor the brain environment and play a role in maintaining brain homeostasis. Although they are part of the brain's defense system, they are not the primary cells responsible for neural communication in the cerebral cortex.

D. Oligodendrocytes: Oligodendrocytes are responsible for producing myelin sheaths that insulate axons, facilitating the rapid transmission of electrical signals within the nervous system. Although they are part of the brain's structural support, oligodendrocytes are not primary cells involved in neural communication in the cerebral cortex.

**Clinical Pearl:** In summary, the correct answer "glial cells" highlights that these cells are essential for brain function but not the primary cells responsible for neural communication in the cerebral cortex, which is primarily attributed to neurons. Understanding the diverse roles of glial cells is crucial in appreciating the complex interplay in the brain's structure and function.