generate questions: In the 21st century, these trends have continued, and several new approaches have come into prominence, including multielectrode recording, which allows the activity of many brain cells to be recorded all at the same time; genetic engineering, which allows molecular components of the brain to be altered experimentally; genomics, which allows variations in brain structure to be correlated with variations in DNA properties and neuroimaging.
Multielectrode recording allows what? {sep_token} Genetic engineering allows what? {sep_token} What does genomics allow the study of? {sep_token} During what century was multielectrode recording invented? {sep_token} Genetic engineering was first discovered in what century?