Brain Facts

The average adult human brain weighs about 3 pounds (1.4 kilograms). Despite being only about 2% of body weight, it uses about 20% of the body's energy.

The brain is about 73% water. Even mild dehydration (just 2%) can affect attention, memory, and other cognitive skills.

The cerebrum is the largest part of the brain, making up about 85% of its total weight. It is responsible for thinking, learning, memory, and voluntary movements.

Each hemisphere has 4 main lobes: frontal (reasoning, planning), parietal (sensory processing), temporal (hearing, memory), and occipital (vision).

Neurons are the brain's information-transmitting cells. The human brain contains approximately 86 billion neurons, each connected to thousands of others.

The cerebellum, located at the back of the brain, controls balance, coordination, and fine motor skills. It contains about 50% of the brain's neurons despite being only 10% of its volume.

Neuroplasticity is the brain's remarkable ability to reorganize itself by forming new neural connections throughout life. This ability is crucial for learning, memory, and recovery from brain injuries.

Information can travel along neurons at speeds up to 268 mph (431 km/h). The speed varies depending on the type of neuron and whether it has a myelin sheath.

Dopamine is often called the 'feel-good' neurotransmitter because it plays a key role in reward, motivation, and pleasure. It is also important for motor control and focus.

The hippocampus is crucial for forming new long-term memories and spatial navigation. Damage to this area can result in an inability to form new memories.

The blood-brain barrier is a highly selective membrane that prevents most substances in the blood from crossing into the brain. It protects the brain from toxins and pathogens.

REM (Rapid Eye Movement) sleep is when the brain is most active in consolidating memories, especially procedural and emotional memories. Deep sleep also helps with declarative memory consolidation.

The adult brain has approximately 100 trillion (10^14) synaptic connections. Each neuron can have thousands of connections to other neurons, creating an incredibly complex network.

The amygdala is responsible for the fight-or-flight response and processing emotions, particularly fear. It can trigger rapid emotional reactions before the conscious brain has time to process information.

Myelin is a fatty white substance that forms a sheath around nerve fibers, insulating them and greatly increasing the speed of electrical impulse transmission. Loss of myelin is associated with diseases like multiple sclerosis.