Inability to delete old info may hinder new learning
It may just be the inability to filter and eliminate old information, rather than a limited capacity to absorb the new that makes learning harder as we age, say researchers in the US.
"When you are young, your brain is able to strengthen certain connections and weaken certain connections to make new memories," said Joe Z. Tsien, neuroscientist at the Medical College of Georgia Regents University (GRU), who led the study.
"It is that critical weakening that appears hampered in the older brain," the journal Scientific Reports said, explaining that the brain's hippocampus is like a switch for regulating learning and memory.
A certain variety of neural receptor (NR2B) is expressed in higher percentages in children, enabling neurons (brain cells) to talk a fraction of a second longer, make stronger bonds, called synapses (junctions that permit neurons to pass on signals to other cells), and optimise learning and memory, the report said.
With changes that set in at puberty, there is a slightly reduced communication time between neurons.
"If you only make synapses stronger and never get rid of the noise or less useful information, then it is a problem," said Tsien, the study's corresponding author.
While each neuron averages 3,000 synapses, the relentless onslaught of information and experiences necessitates some selective whittling.
"We know we lose the ability to perfectly speak a foreign language if we learn that language after the onset of sexual maturity. I can learn English, but my Chinese accent is very difficult to get rid of. The question is why," Tsien explained.