 Earlier in this module, we learned that much of our understanding of brain structure and function developed as a result of accidents. But what are the key brain structures and which of these are critical for human learning? The human brain is very much an interconnected web of parts, but the three major areas are the cerebrum, the cerebellum and the brainstem. The brainstem connects the brain with the spinal cord and controls biological processes like breathing, digestion and heart rate. The cerebellum contributes to balance and motor control, but also to cognitive functions like language, attention and regulating emotions like fear and pleasure. The cerebellum is also involved in procedural memory which is the unconscious memory of skills and using objects like riding a bicycle. The cerebrum is the largest region in the brain and is divided into two hemispheres left and right. There are symmetrical pairs of most of the key parts of the cerebrum in each hemisphere, such as the hippocampus and the temporal lobes. The neocortex is a sheet of neural tissue that covers the cerebrum and contains about 90% of the brain's neurons. The neocortex is critical to memory, attention, perceptual awareness, thought, language and consciousness. The neocortex itself is divided into four regions or lobes across both hemispheres, the frontal lobe, the parietal lobe, the temporal lobe and the occipital lobe. In terms of human learning, the frontal lobe and particularly the prefrontal cortex are important for decision making and processing and retaining short and longer term memories. The temporal lobe processes speech and vision and is also important to forming long term memory. Inside the temporal lobe is a section that plays a role in declarative and episodic memory. Inside that is the limbic system. This includes the hippocampus and the amygdala and many other organs which are associated with forming and processing memory. The hippocampus is critical to memory function, specifically transferring information from short to long term memory. The amygdala is involved with processing and remembering emotional reactions. But these aren't totally localized discrete functions. For example, both the cerebellum and the amygdala regulate emotion. Both the temporal lobe and the amygdala regulate the sense of smell. This illustrates the complex interconnectedness of the various brain structures.