In the next few years were going to see a lot of technology demonstrations in which one very narrow biochemical aspect of aging is reversed in laboratory animals - these are the first few pebbles in what will become an avalanche of rejuvenation biotechnology. You might recall the reversal of lysosomal functional decline in the livers of mice in 2008 as an example of the type. Here is one for the brain: "Drugs that affect the levels of an important brain protein involved in learning and memory reverse cellular changes in the brain seen during aging, according to an animal study. ... [Aging] affects brain cells' ability to alter the strength and structure of their connections for information storage, a process known as synaptic plasticity, which is a cellular signature of memory. ... compared with younger rats, hippocampi from older rats have less brain-derived neurotrophic factor (BDNF) - a protein that promotes synaptic plasticity - and less histone acetylation of the Bdnf gene. By treating the hippocampal tissue from older animals with a drug that increased histone acetylation, they were able to restore BDNF production and synaptic plasticity to levels found in younger animals. ... The researchers also found that treating the hippocampal tissue from older animals with a different drug that activates a BDNF receptor also reversed the synaptic plasticity deficit in the older rats."