The 12 primitive reflexes of infants

The absence of these movements in newborns is usually a sign of neurological disease.

Throughout our development as a species, humans have inherited reflexes from our non-human ancestors, behaviors that depend on the central nervous system and occur in response to certain types of stimulation. A special case is that of primitive reflexes, which appear in infants but are lost a few months later but are lost within a few months of life.

In this article we will see what these reflexes of ancestral origin are and how they are expressed during the first weeks after birth.

The primitive reflexes of infants: types and characteristics

The reflexes are The activation patterns of movements that are triggered by certain stimuli and that occur automatically and outside of our consciousness, and always in the same way, and that are caused by nerve cells that are not part of the brain.They are caused by nerve cells that are not part of the brain. They are usually caused by an adaptation to the environment, since the nerve cells that trigger them form a network of interconnections that does not pass through the brain, so that very little time passes between the reception of the stimulus and the appearance of the reaction, which in certain situations helps us to avoid dangers.

However, sometimes these reflexes become useless as a lineage of animals evolves and moves further and further away from the type of behaviors and ecological niche that were useful in the past. This is what happens with some of the primitive reflexes of infants: These are "remnants" of adaptive mechanisms that were useful millions of years ago, but that are no longer useful, giving way to another type of nervous system functioning.but, since they are no longer useful, they give way to another type of functioning of the nervous system, so that their existence in the members of our species only lasts a few weeks. In other cases, they are mechanisms that are only useful when we are babies, and that can occur without the need for the child to be able to plan action patterns or to have clear objectives to achieve.

Below we will describe 12 of the most characteristic primitive reflexes of early childhood. Unlike the blink reflex, the refractive reflex or the patellar reflex, primitive reflexes are not maintained during adulthood; their origin is associated with increased survival of infants under the conditions in which our species evolved.

The absence of these reflexes is a sign of neurological problems.The presence of primitive reflexes at developmental stages when they should not remain is also indicative of some kind of brain disturbance. Conversely, the presence of primitive reflexes in developmental stages when they should not remain also indicates some kind of brain alteration.

1. Grasping

Before reaching about half a year of age, infants are able to grasp objects with their fingers if they press against the palm of one of their hands. At an adaptive level, it allows infants to suspend their own weight for a short period of time. The origin of this reflex probably has to do with the times when babies clung to their mothers' or fathers' fur.

2. Searching or rooting

The search or rooting reflex is associated with breastfeeding: when babies under 4 months of age notice that something touches their cheek or mouth, they turn their head towards the object and open their mouth, turn their heads towards the object and open their mouths to suck on it.. This reflex is also detected in some adults with severe cerebral palsy.

3. Sucking

The sucking reflex acts in a complementary way with the search reflex. When they notice that something touches their palate, babies instinctively squeeze it with their tongue; The function of this reflex is to promote the secretion of milk from the mother's nipple. by the mother's nipple.

4. Reptation

This behavior appears when the baby's belly is supported on a surface and the foot is held; the baby begins to move all four limbs in a coordinated manner to move along the floor. At 4 months this reflex is no longer present.

5. Automatic walking

As its name suggests, this reflex allows infants to take steps rhythmically when held upright when held upright with their feet uncovered on a flat surface. It disappears between 2 and 3 months of life as a consequence of changes in the relative weight of the legs.

6. Swimming

If a baby is held with its belly against the water, for example in a bathtub or at the beach, it begins to move its arms and legs and exhale air through its mouth, although it may swallow a lot of water in the process. The swimming reflex disappears by 6 months of age.

7. Moro or startle reflex

The Moro, startle or cuddle reflex is produced when babies under 5 months of age hear a sudden loud noise.. Stimulation of this type causes them to first extend their arms and legs and then close their arms against their own body. This reflex would help babies to stay attached to their mothers while being carried.

8. Babinski's

When the side of an infant's foot is tapped, the infant extends the big toe backward and spreads the other toes apart while twisting the foot inward. The absence of this reflex often indicates insufficient myelination of the brainstem motor pathways.

9. Magnus or tonic-cervical

The asymmetric tonic neck reflex causes infants to turn their heads to one side and adopt a protective posture when they are laid on their backs. It is a behavior that precedes eye-cervical precedes the coordination between the eyes and hands.. It is also sometimes referred to as the "fencer's reflex" or "fencing position".

10. Landau's

This reflex, which disappears at 3 to 4 months of age, is triggered when the baby is suspended face down and head flexed. It first extends the head, trunk and legs, and then flexes the rest of the body. One of the primitive reflexes that involve more muscles.

11. Babkin's or palmarmental

Babkin's reflex is triggered by pressing the two palms of the baby's hands while lying on his back. on its back. When this happens, the baby opens its mouth, closes its eyes and turns its head. It also ceases to appear between 3 and 4 months of life.

12. Galant's reflex

The infant Galant reflex is present during the first 6 months after birth. It consists of the turning of the body, with a search or orientation function, when the baby notices that his back is being touched.

Bibliographical references:

• Fletcher, Mary Ann (1998). Physical Diagnosis in Neonatology. Philadelphia: Lippincott-Raven.
• Grzywniak, C. (2016). "Role of early-childhood reflexes in the psychomotor development of a child, and in learning". Acta Neuropsychologica. 14(2): pp. 113 - 129.
• Pedroso, F.S.; Rotta, N.T.. (2004). Babkin Reflex and Other Motor Responses to Appendicular Compression Stimulus of the Newborn. Journal of Child Neurology, 19(8): pp. 592 - 596.