A neurodevelopmental basis for a range of learning difficulties, including reading delay, is suggested by the clinical and research evidence linking the persistence of primary reflexes(1, 2) with learning difficulties.
What are primary reflexes?
Primary reflexes are movement patterns which emerge during fetal life and are critical for the survival of the newborn - e.g. infant rooting and suck reflexes. They are obvious during the first six months of life(3) and primary reflex tests are routinely used by paediatricians to assess the neurological integrity of the newborn baby. As the nervous system develops, however, they are inhibited or transformed and the persistence of primary reflexes beyond their normal timespan (12 months) interferes with subsequent development and indicates neurological impairment.(4) More than 70 primary reflexes have been identified(5) and they may be classified in several ways - e.g. according to function, time of appearance or the type of stimulus which releases them.
Some examples
Some reflexes are obvious and familiar - e.g. the grasp reflex (where the newborn grasps a finger placed in its palm) and the Moro reflex. The Moro reflex is usually stimulated by a sudden movement of the head backwards but it may also be activated through a sudden change of light or a loud noise. The response consists of an immediate wide abduction of the arms (both arms are flung out from the body), and a rapid intake of breath. This is followed by the arms coming together again as if to embrace or grasp.
The response usually includes flexion of the legs, tensing of the back muscles and crying. The strength and symmetry of response are very useful diagnostic indicators in a neurological examination of the newborn. The Moro reflex is not normally seen after 6 months of age and is transformed into the adult startle pattern.
Other primary reflexes are less well known - e.g. the Tonic Labyrinthine Reflex (TLR) and the Symmetrical Tonic Neck Reflex (STNR). The TLR is active during the birth process, where the baby retracts or pushes back its head, flexes or folds in its arms and extends or straightens its legs. If the baby is in a posterior presentation (face up) before birth the head will push into the mother's spine causing great pain. This reflex can be felt in the newborn by simply pushing on the back of the head. The baby will immediately resist and push backwards. At around 3 months the TLR enables the baby to lie on its front and lift up its head. It must be inhibited or switched off, however, before the baby can come up into a crawling position at around 8-9 months. If the TLR is still present at this stage the baby is not able to support its weight by straightening its arms and bringing its knees beneath its body.
The transition up into a crawling position is assisted by the emergence of the STNR which enables extension of the arms and flexion of the legs at the same time. However, the STNR has to be 'switched off' before the baby can crawl forward as this involves a combination of flexion and extension - e.g. in a cross-pattern crawl the right arm and left leg flex while the left arm and right leg extend.
Crawling is a major developmental milestone. It represents the transition from fetal/infant movement, which is dominated by primary reflexes, to movement which allows the young child to explore its surroundings independently. At around 12 months, the baby, which began life in the fluid environment of the womb, may be ready to take its first tentative steps on 'dry land'.
Persistence of primary reflexes
In normal development the primary reflex system is inhibited or transformed in the first year of life and a secondary or postural reflex system emerges. The secondary system forms the basis for later adult coordinated movement. However, primary reflexes may persist for certain children beyond their normal timespan and disrupt subsequent development.
For example, the persistence of the Asymmetrical Tonic Neck Reflex (ATNR) will lead to problems which are particularly apparent in an educational setting. The ATNR is most obvious in the first three months after birth and is elicited by a sideways turning of the head when the baby is supine. The response consists of extension of the arm and leg on the side to which the head turns and flexion of the opposing limbs. The ATNR is involved in the orientation of the newborn in space and, as it is present when near point fixation is developing, plays an important role in visuomotor development. It should be inhibited around 6 months of age and persistence is a clinical indicator of abnormal development.
Severe persistence of primary reflexes indicates predominantly intractable, 'organic' problems as in cerebral palsy(6) where children experience extreme motor difficulties and significant reading difficulties despite adequate levels of intelligence(7) . Relatively milder persistence, however, is associated with less severe disorders (including specific reading difficulties). The process of inhibition of these reflexes in the earliest months of life remains unknown but it has been assumed that this process cannot occur after early childhood.
Neonatal movement is largely stereotypical(8) and follows the patterns of the primary reflex system. The early movements of the fetus and newborn which were previously viewed as passive byproducts of rapid neural wiring are now viewed as 'interactive', having a reciprocal effect on underlying CNS structure and functioning(9). This suggests that the actual rehearsal and repetition of primary reflex movements play a role in the inhibition process itself.
Research
The effects of the Primary Movement programme, which is based on replicating or mimicking the primary reflex system of the fetus, has been evaluated in a number of formal studies that have been published in peer-reviewed scientific journals. In a double-blind, placebo controlled study, it was found that children who completed the Primary Movement programme made very significant gains in reading, writing speed, naming speed and saccadic frequency (eye movements) with a concurrent significant inhibition of the ATNR(10).
In a school-based study involving more than one thousand children, it was found that the Primary Movement programme had a significant effect on ATNR persistence and academic attainments (reading, spelling and mathematics)(11).
These studies suggest that the repetition of primary reflex movements play a major role in the inhibition of primary reflexes and that inhibition can be brought about at a much later stage in development than had previously been assumed.
References
1 Morrison DC. Neurobehavioral and Perceptual Dysfunction in Learning Disabled Children. Lewiston, NY: C.J. Hogrefe, Inc., 1985.
2 McPhillips M, Sheehy N. Prevalence of persistent primary reflexes and motor problems in children with reading difficulties Dyslexia 2004; 10(4): 316-338
3 Capute AJ, Shapiro BK, Palmer FB, Accardo PJ, Wachtel RC. Primitive reflexes: A factor in nonverbal language in early infancy. In : Stark, ed. Language Behavior in Infancy and Early Childhood. North Holland: Elsevier, 1981: 157-161.
4 Holt KS. Child development: Diagnosis and Assessment. London: Butterworth-Heinemann, 1991.
5 Illingworth RS. The development of the infant and young child: Normal and abnormal. Edinburgh: Churchill Livingstone, 1987.
6 Bobath B, Bobath K. Motor Development in the Different Types of Cerebral Palsy. London: Heinemann Physiotherapy, 1975.
7 Seidel UP, Chadwick O, Rutter M. Psychological disorders in crippled children: a comparative study of children with and without brain damage. Developmental Medicine and Child Neurology 1975; 17: 563-573.
8 Thelen E. Rhythmical stereotypes in normal human infants. Animal Behavior 1979; 27(4): 699-715.
9 Prechtl HFR. Continuity and change in early neural development. In: Prechtl HFR, ed. Continuity of neural functions from prenatal to postnatal life. Oxford: Blackwell Scientific, 1984: 1-15.
10 McPhillips M, Hepper PG, Mulhern G. Effects of replicating primary-reflex movements on specific reading difficulties in children: a randomised, double-blind, controlled trial. Lancet 2000; 355: 537-41.
11 Jordan-Black J-A. The effects of the Primary Movement programme on the academic performance of children attending ordinary primary school. Journal of Research in Special Educational Needs 2005; 5(3): 101-111.