During fetal development primitive reflexes emerge as part of human life preservation. They allow a newborn to instinctively react to his or her environment. These reflexes are seen in a newborn’s ability to grasp a parent’s finger tightly without letting go. Another primitive reflex seen in newborns is the ‘startle reflex’, in which the baby will react or jerk to a sudden loud sound. These primitive reflexes should be present at birth and provides an indication of the status of the baby’s Central Nervous System (CNS). These indications are recorded at birth as Apgar test scores.
During the first year of life these primitive reflexes should slowly become inhibited as the more mature reflexes, known as postural reflexes begin to emerge. These postural reflexes aid the infant in coping with the demands of the new gravity based environment.
If primitive reflexes remain present after birth and/or postural reflexes are absent or do not emerge during development, this may create motor, sensory and development delays.
Individually retained primitive reflexes impair specific areas of functioning. For example, one reflex will prevent automatic hand control every time the head is moved, so that writing can never become fluent. Another retained reflex will adversely affect the coordination of balance and smooth eye movements, so that in certain situations the eyes will play “tricks”, and the letters on the page will appear to “dance”, or, may appear in a different order from one day to the next. Other retained reflexes may cause the child may be “stimulus bound”, so that his eyes are automatically drawn to anything moving within his visual field, and in a classroom he will be distracted easily.
Important development stages correspond very closely to reflex chronology (inhibition to emergence). The following is a list of reflexes and subsequent issues that can occur if primitive reflexes are retained or postural reflexes do not emerge during development.
The Moro Reflex
Emerges around 8-9 weeks in utero and is inhibited at about 16 weeks of neonate life, and should not be present in children beyond the age of one year at the very, very latest.
It is a panic alarm reflex which helps the baby to hang on and cry in alarm. The startle reflex is a rapid intake of breath, blinking, shoulders go up as the baby locates the source. Agorophobia panic victims, for example, still retain the Moro reflex. It can be activated by a sudden noise, movement/alteration of head position or change of light. It can transform into the adult startle reflex known as the Strauss Reflex.
Children who retain Moro Reflex may seem to be immature, very sensitive, over-reactive, often lose control, and their pupils tend to remain enlarged under minimum stress. Pupils are more dilated than normal because of the fight/flight mechanism. Many children with a strong retained Moro Reflex become hypersensitive to light. Behavior issues become more pronounced since many children with a strong Moro Reflex do not learn from experience. They also tend to burn up blood sugar quicker than other children, which will make mood swings and poor performance more pronounced.
Adults who retain a Moro Reflex exhibit the adult startle or Strauss reflex. If a person grows up with this reflex but manages to control it, it can affect the entire personality. The adult may need to ask question after question and are typically tnot happy about change unless they have instigated it. If they are going somewhere they want to know who will be there, what will happen and what they will have to do. They may seem to be uptight and egocentric, not because they want to be, but because they need to be in control as much as possible. They also may find it difficult to make lasting relationships as they need to control the other person.
The Palmar Reflex
Emerges at around 11 weeks in utero and is inhibited or suppressed at about 2-4 months after birth. It is activated by stimulation in the palm of the hand.
The Palmar reflex should not be present beyond the first year of life, but if it remains present in children of school age, writing problems will develop. As soon as a pen or pencil is put into the child’s hand, the fingers automatically tighten, and get tighter and tighter. The pressure increases on the paper and they start to lose control of the hand. They may find it hard to move the fingers and thumb for rapid alternate movement (dysdiadochokinesia), which futher indicates an immaturity of the cerebellum. Poor speech and language is a likely consequence.
The cerebellum does not cross over, and so if you cannot do the movement on the right side, it shows that there is a problem in the right side of the cerebellum. In the early months of life the Palmar Reflex can be activated by sucking movements. The hands and the mouth are linked together in what is called the Babkin response. The hands and the mouth are the baby’s main tools for exploration and for expression. Residual reflexes in these areas can affect speech and articulation as well as fine muscle control.
The Asymmetrical Tonic Neck Reflex (ATNR)
Emerges at around 18 weeks in utero and is inhibited or suppressed between 6-8 months after birth, while awake. It persists up to three and a half years while asleep.
The ATNR fulfils many purposes. It may help survival. When a baby is placed prone, the head should go to one side, with extension of the arm and leg. This allows free passage of air. The ATNR is the first training ground for eye-hand coordination. Through the ATNR, the baby slowly extends the vision from near point fixation to distance, and therefore this is vital for eye-hand coordination training. This reflex is activated by head rotation to either side.
If the ATNR remains present after 8 months of birth it might affect crawling. The child is unable to reach and then bend the elbow to drag itself along (it is physiologically impossible to creep, commando style). In an older child, it is as though there is an invisible force which causes the arm and hand to straighten whenever the head is turned to one side. The child may have to exert a great deal of conscious control when writing – something that should be automatic. In addition to the fatigue caused by the effort of fighting the reflex, the child’s comprehension can suffer due to the cortex being involved in movement.
A retained ATNR can also affect vision. The hand does not want to cross the midline, and as the eyes are locked in to the hands, they do not want to cross the midline either. This can affect reading, in that when the eyes get to the midline, they “jump” and the reader may lose his/her place.
Judging distance will also be difficult. If present in the legs, walking will be affected, and the child will tend to walk with a stiff leg gait. Catching a ball (bringing the hands together at the midline) will be affected. When the head turns right, the left knee will bend and therefore disturb balance.
Gross and fine muscle coordination and eye tracking will be affected. Many children who are articulate and bright just cannot seem to express themselves well in written work. It is as though the mind can think and the mouth can speak, but when a motor task is added (writing, for example) the child seems unable to demonstrate the skill needed.
The Tonic Labyrinthine Reflex (TLR)
Emerges around 3 – 4 months in utero (in flexion, or forwards) and at birth (in extensio or backwards) and is inhibited or suppressed between 3 -4 months after birth (in flexion) and 3 – 4 months to 3 and a half years (in extension).
This reflex is known as “the baby balance reflex”. It plays a role in the development of muscle tone, a process which also helps to train balance and proprioception (the awareness of the position of the body or limbs).
This reflex is activated by head movement above and below the level of the spine. If the TLR primitive reflex remains present – eyes, balance and proprioception can be adversely affected. Head movement can affect muscle tone (‘floppy’ child – low or weak muscle tone), and this can cause a lack of center of balance. The brain will lack a reference point to judge space, depth, distance and speed, and this can cause problems with understanding where the body is in space, depth perception and difficulty with directions such as left, right, up, down. This can make spatial tasks difficult.
The ability to track smoothly and evenly with the eyes only comes about as the TLR primitive reflex in extension is inhibited, and the continued presence of the TLR prevents the proper emergence of the Head Righting Postural Reflexes. As the eyes and ears operate on the same circuit of the brain (even sharing cranial nerves), poor visual information will affect balance, and poor balance will affect vision.
The Symmetrical Tonic Neck Reflex (STNR)
Emerges around 9 – 11 months after birth and is inhibited or suppressed at about one year.
It has a very short, significant life. The sole task of the STNR is to get the child to begin to defy gravity. Every time the baby looks up the bottom goes back onto the ankles, and every time the baby looks down the elbows bend and the head virtually hits the floor.
A retained STNR Primitive Reflex will make it impossible for the baby to crawl..and the baby may become a bottom hopper. In around 75% of LD children there is a retained STNR (Goddard, S., 1998).
Later, during school age a retained STNR will be noticed during writing. The elbows bend and the head goes nearer and nearer to the writing surface. Many of these children are messy eaters. As they use a spoon, their head goes down. They do not have control over the hand and head movement, and therefore spill as much food as they put in their mouth. These children tend to compensate by lifting the spoon up and putting their head down.
The STNR has been associated with reading, writing and concentration problems. It will also affect copying and spelling and has a definite, noticeable effect on posture and movement. It is very closely tied in with the TLR.