The most intriguing early results suggest Scott Kelly experienced changes in the expression of thousands of genes; earlier this year, NASA reported that 7% of them—related to immune function, DNA repair, bone formation, and his body’s response to insufficient oxygen and abnormally high carbon dioxide levels in the blood—remained some 6 months after his return to Earth.
Indeed, the cerebral cortex in the human brain, which is accountable for high cognitive functions such as language, memory and movement, contains approximately 16 billion neurons – the cerebral cortex of a mouse contains around 14 million neurons. Similarly, the brain of a mouse weighs around 400 mg whereas a human brain weighs roughly 1,500,000 mg.
