Does Brain Shrinkage Really Matter?

Do you belief that adult brain cells, or neurons, are largely static ? Does it really matter?

According to a new study of 446 people in Australia, scientist found that brain shringkage will not reduce brain function."We found that, on average, men aged 64 years have smaller brains than men aged 60," said Helen Christensen of the Australian National University. "However, despite this shrinkage, cognitive functions like memory, attention and speed of processing are unaffected."

Scientist also found that educational level have no relation with brain shrinkage. Previous studies had indicated that higher levels of education or continuing intellectual activity could serve as a sort of Pilates for the brain, keeping an aging mind fit. Older minds do sometimes fail, of course, owing to conditions such as Alzheimer's that scientists are only beginning to understand.

Altough adult's brain growing much slower than during the early years of following birth, neuron's network keep changing structurally. "The scale of change is much smaller than what goes on during the critical period of development, but the fact that it goes on at all is earth-shattering,"said study co-author Elly Nedivi, a neuroscientists at the Massachusetts Institute of Technology (MIT).

During the early years following birth, humans manufacture an estimated 250,000 neurons per minute and then spend the next few years wiring them together. Traditionally, it was assumed that this neural plasticity settles down by adulthood.

Neurons communicate with one another by exchanging either electrical or chemical signals across tiny gaps where two neurons meet, called synapses. The signals can be either excitatory or inhibitory, meaning they either increase or decrease, respectively, the activity of the neuron they're affecting.

The researchers estimate that on average, about 14 percent of the interneurons they observed showed structural modifications.

Approximately 20 to 30 percent of the neurons in the neocortex, the part of the brain responsible for higher functions such as thought, are made up of inhibitory interneurons. These neurons are believed to play an important role in regulating brain activity by delaying or blocking signals from excitatory neurons.

The researchers speculated whether interneurons might be largely responsible for neural plasticity in adult brains.