(p. C2) . . . , if a baby monkey heard a new sound pattern many times, her neurons (brain cells) would adjust to respond more to that sound pattern. Older monkeys’ neurons didn’t change in the same way.
At least part of the reason for this lies in neurotransmitters, chemicals that help to connect one neuron to another. Young animals have high levels of “cholinergic” neurotransmitters that make the brain more plastic, easier to change. Older animals start to produce inhibitory chemicals that counteract the effect of the cholinergic ones. They actually actively keep the brain from changing.
. . .
In the new research, Jay Blundon and colleagues at St. Jude Children’s Research Hospital in Memphis, Tenn., tried to restore early-learning abilities to adult mice. As in the earlier experiments, they exposed the mice to a new sound and recorded whether their neurons changed in response. But this time the researchers tried making the adult mice more flexible by keeping the inhibitory brain chemicals from influencing the neurons.
In some studies, they actually changed the mouse genes so that the animals no longer produced the inhibitors in the same way. In others, they injected other chemicals that counteracted the inhibitors. (Caffeine seems to work in this way, by counteracting inhibitory neurotransmitters. That’s why coffee makes us more alert and helps us to learn.)
In all of these cases in the St. Jude study, the adult brains started to look like the baby brains.
For the full commentary, see:
(Note: ellipses added.)
(Note: the online version of the commentary has the date July 7, 2017, and has the same title as the print version.)
The article co-authored by Jay Blundon and mentioned above,is:
Blundon, Jay A., Noah C. Roy, Brett J. W. Teubner, Jing Yu, Tae-Yeon Eom, K. Jake Sample, Amar Pani, Richard J. Smeyne, Seung Baek Han, Ryan A. Kerekes, Derek C. Rose, Troy A. Hackett, Pradeep K. Vuppala, Burgess B. Freeman, and Stanislav S. Zakharenko. “Restoring Auditory Cortex Plasticity in Adult Mice by Restricting Thalamic Adenosine Signaling.” Science 356, no. 6345 (June 30, 2017): 1352-56.