Brain Neuroscience

The human brain contains approximately 86 billion neurons, each connected to up to 10,000 others, creating roughly 100 trillion synaptic connections. It consumes 20% of the body's energy while comprising only 2% of body weight. Despite being the most studied object in science, the brain remains profoundly mysterious — consciousness, memory formation, and subjective experience remain poorly understood. Recent advances include optogenetics (controlling individual neurons with light), fMRI brain mapping, connectomics (mapping every neural connection), and brain-computer interfaces (Neuralink). The Human Connectome Project aims to map every neural connection in the human brain — a project that may take decades. The 2013 US BRAIN Initiative allocated $4.5 billion to neuroscience research.