Neuromyth # 3

So far we discussed the myths around left/right brain and around how little we use our brain.

Today we will talk about the myth around critical period for neuroplasticity.

Myth: There are certain periods (referred as critical periods) during early life when the brain’s capacity for adjustment in response to experience is substantially greater than it is in adulthood.

In simple words, the myth states that our brains are hardwired however the truth states the opposite.

Truth: The human brain has the ability to change throughout life as a result of behavior, environment, emotions, thought, etc. The phenomenon is called as neuroplasticity

For example though children can benefit from learning a second language during a period of high neuroplasticity (also referred as critical period or sensitive period), it does not mean that adults cannot learn a second language. Recent studies have clearly shown that critical periods are not sharply delineated. They are influenced by many factors like input types, modality etc.

Critical periods or sensitive periods generally coincide with periods of excess synapse formation in the brain, and end at around the same time that synaptic levels stabilise.

While there might be sensitive periods for some stimuli (visual, auditory etc), the capacity to form synapses, i.e. plasticity, is not limited to the first three years of life. It cannot be generalised that there is a sole sensitive period (up to 3 years) for every possible stimuli. Any kind of specific environmental stimulation causes the brain to form new connections. This ability is conserved throughout life. So keep learning throughout your life.

🥂 to neuroplasticity!

If you are keen to know where did this myth of critical period stem from here is an account. It came from the observations of imprinting in birds by Konrad Lorenz.

Lorenz observed that a newly hatched bird gets imprinted (attached) to its mother. This happens right after hatching (referred as a critical period).  The hatchlings follow their mothers and nothing alters this behavior. A correlation is noticed between this imprinting and the neuronal development.

A similar model is observed in guinea fowl, but this time the imprinting is to auditory stimulus. Similarly in kittens it is observed that if one eye is closed during the critical period, the visual cortex doesn't fully develop. These observations led the scientific community to believe that there are some critical periods or sensitive periods during the developmental stage where the neurons select their repertoire of inputs from a larger array of available inputs and sticks to it.

The problem is the research findings are primarily from the visual and auditory systems and not from cognition and learning. Though sensory deprivation can impede development, it doesn't take away the possibility of learning in the future.

Don't believe these misconceptions and stop learning. Keep going!