What is the outer layer of the brain often referred to as gray matter?

The outer layer of the brain, known as the cerebral cortex, is often referred to as gray matter due to its appearance and composition. The cerebral cortex is primarily made up of neuronal cell bodies, which contain grayish pigment that gives this layer its characteristic color. This region is crucial for many high-level functions, including perception, cognition, and voluntary motor control.

In contrast, the other options do not represent the outer layer of the brain. The basal ganglia are a group of subcortical structures involved in movement regulation, while the medullary body refers to the medulla, which is part of the brainstem responsible for autonomic functions. Gyri are the folds or ridges on the surface of the cerebral cortex but do not refer to the outer layer itself. Understanding the unique characteristics and functions of the cerebral cortex highlights why it is specifically labeled as gray matter.