Primitive reflexes: What are they? What are they for? Why do they disappear? In this article I will try to answer all these questions.
What are they?
They are automatic, stereotyped movements, directed from the brainstem and executed without involvement of the cortex. They arise in the uterus and are present at birth, to be integrated and inhibited at 6 months.
What are they used for?
They are essential for the survival of the newborn in its first weeks of life. They disappear to give way to more complex reflexes that we call postural reflexes that remain throughout life.
Why do they disappear?
As the higher cortical centers take control, the lower centers are inhibited to allow the evolution of more sophisticated neurological structures that involve movement consciousness.
It is only possible to be aware of primitive reflexes when the cortex is involved in the event.
What happens if they are not inhibited?
If these reflexes remain active after 12 months of life they are called aberrant and represent evidence of CNS structural weakness or immaturity.
Primary reflexes active after 6 months of life may result in immature behavior patterns or may cause them to remain immature, even though the child has acquired more sophisticated later skills.
Inhibition and acquisition
- Depending on the degree of aberrant reflex activity this poor nerve fiber organization may affect one or all areas of functioning: motor, fine, gross coordination, perception, cognition, and expression.
- Inhibition of a reflex is almost always related to the acquisition of a new skill.
- That is why it is important to know the timing of reflexes and normal child development to predict which late ability may have been impaired.
Early detection: what is it and what is it useful for?
Early detection allows us to identify and integrate, by means of rhythmic movements, the reflexes exactly where they had been retained, recovering the functional state.
Thelan (1979) observed that all human babies during their first year of life make the same stereotyped movements because they contain an inhibitor. So if the child has never made such a movement in the correct order, the reflexes may remain active as a result.