What part of the brain is commonly referred to as the "thinking" part?

The cortex is often referred to as the "thinking" part of the brain because it is the outermost layer of the brain that is responsible for many higher-order functions, including thought processes, reasoning, problem-solving, and decision making. It plays a crucial role in sensory perception and motor commands, and different areas of the cortex are specialized for different cognitive functions.

In contrast, the cerebellum is primarily involved in coordination and balance rather than conscious thought. The medulla oblongata regulates vital functions like breathing and heart rate, functioning largely without conscious thought. The thalamus acts as a relay station for sensory information but does not engage in thinking processes itself. Therefore, the cortex is accurately identified as the region of the brain responsible for the complex cognitive activities often associated with thinking.