Findings from neurobiology research are presented as ‘medical evidence’ by politicians Graham Allen and Iain Duncan Smith to support their proposals for early intervention programmes for children from deprived backgrounds. Before looking in detail at what they have to say about brain development, it might be helpful if I summarise my understanding of the process. It squares with the account cited by Munro here ; so I’m assuming I’m on the right track.
Brain development is an outcome of the interaction between four factors ;
• epigenetic (the impact of the environment on gene expression)
• environmental (from nutrition to the behaviour of others)
• behavioural (the impact of the child’s own behaviour)
The relative impact of the different factors varies between individuals and at different stages of development.
The number, formation and location of brain cells (neurons) is almost entirely genetically determined, although it can be affected by environmental factors. A baby has a full complement of neurons at birth, although some neurogenesis occurs in some areas of the brain in adults.
Interconnections between neurons are formed by synapses.
The evidence suggests that the role of synapses in learning is essentially a three-stage process.
Novel patterns of sensory input result in new synapses being formed (synaptogenesis). The number of synapses in the brain increases dramatically in the first three years after birth, running into trillions – far more than are found in adult brains.
If the same patterns of sensory input are repeated, some neuronal connections are reinforced and others weakened by synapses dying off (synaptic pruning), resulting in the formation of efficient information-processing pathways.
A third stage, myelination, takes place when neuronal pathways that are used repeatedly develop a fatty myelin sheath that greatly increases the speed of transmission of electrical impulses along the neurons. This makes some processes very fast and they are experienced as ‘automatic’.
Learning also appears to be kick-started by genetically-controlled factors such as the underlying structure of the brain and reflex responses. Reflexes are automatic, unconscious motor responses to stimuli , ranging from tongue protrusion to the step-reflex that forms the basis for later walking .
When DNA divides during the formation of gametes (eggs and sperm), and then recombines at conception, it is susceptible to the deletion, duplication and transposition of genetic material. Because of these genetic variations, and the impact of epigenetic factors during development, each human being is genetically unique. This means that due to genes alone, one would expect to find a wide range in abilities, behaviours and personalities across a large population. This variation would increase through interaction with environmental factors.
The second chapters of the papers by Allen and Duncan Smith are about brain development and particularly about how maltreatment and neglect can affect it. Although I can see what these chapters are getting at, my impression is that they include a number of misunderstandings, over-simplifications, assumptions and statements that are simply incorrect. This is a long post – I’ve detailed several examples.
1. “Human infants arrive ready to be programmed by adults. From our first moments of life we are tuned into the facial expressions of those around us, as can be seen from the infant reflex to mimic.” (p.56)
Although there’s no doubt that children are influenced by adults, I think many parents and teachers would question whether they can be ‘programmed’; if that were the case, children with good parents would consistently display exemplary behaviour.
It’s not clear what is meant by a ‘reflex to mimic’. A reflex is an automatic response to a stimulus. Mimicry (in humans) involves copying an action made by someone else. Newborns do appear to mimic some facial movements such as mouth opening and tongue protrusion, although it’s not clear whether this is a reflex response (e.g. tongue protrusion occurring in response to objects moving toward the baby’s face ) or active mimicry. In addition, there is the question of which adult behaviours children mimic, since they clearly don’t mimic all of them, which suggests that mimicry isn’t a reflex. Newborns are indeed tuned in to facial expressions, but whether that’s because the infant visual system is good at pattern-matching and adult faces are a frequently encountered visual pattern, or whether infants have an inbuilt preference for faces is still unclear.
2. “The problem is that this wonderful advantage turns into a disadvantage when it is met by the longterm lack of positive expression on the nearest face, that of the primary caregiver. When this most basic need for a positive response is not met, and when a tiny child does not feel secure, attached and loved, the effect can be lifelong. Neuroscience can now explain why early conditions are so crucial: effectively, our brains are largely formed by what we experience in early life.” pp.(56-57)
This statement assumes that from the ‘first moments of life’ a baby recognizes a positive facial expression, is capable of feeling security, attachment and love, and that the absence of these feelings can have a lifelong effect. There’s no doubt that what a newborn experiences affects brain development, but no evidence is cited for a basic ‘need’ in newborns for any particular facial expression or affect state.
Neuroscience does not claim that ‘our brains are largely formed by what we experience in early life’. Quite the contrary; what it claims is that our brains are formed by the interaction between genetic expression and experience. In the first moments of life genetic factors are disproportionately predominant because the child has had very little experience.
3. “As synapses are also strengthened and reinforced by experience, early life defines which of them live and which die. Synapses become ‘hard-wired’, or protected, by repeated use, enabling very rapid learning via early life experience. Conversely, just as a memory will fade if it is hardly ever accessed, unused synapses wither away in what is called ‘pruning’. In computer terms what takes place is the software (programming by the caregiver) becomes the hardware (the child’s fully-grown brain). The whole process has the effect of making early learned behaviour resistant to change.” (p.57)
If this model were correct, adults would be unable to learn anything. They wouldn’t be able to correct early misconceptions because the relevant synapses would be ‘protected’, nor would they be able to develop new skills because the relevant synapses would have ‘withered away’ through early lack of use. The term ‘hard-wired’ is usually used to refer to biologically determined connections in the brain (those that don’t rely on information from the environment), not to neural pathways developed via experience. Training in the armed forces and emergency services demonstrates that well-established patterns of what’s normally considered instinctive behaviour (panic, aggression etc.) can be over-ridden, provided enough rehearsal of new behaviours takes place. And the Cambridge delinquency study shows that violent and aggressive behaviour in young males falls off rapidly as they get older indicating that behaviour patterns are not set in stone.
In addition, the passage allocates all experience to ‘programming by the caregiver’ as if children receive no other environmental input. This might be the case for a child kept in a sound-proofed, darkened room, but for most children, however deprived, the caregiver’s ‘programming’ forms only a part of the input from the environment.
4. “To summarise: scientific discoveries suggest it is nurture rather than nature that plays the lead role in creating the human personality.” (p.57)
What scientific discoveries actually suggest is that nature and nurture play an approximately equal role in influencing human behaviour and that their relative contributions vary throughout the lifespan. Much of the environmental variation is due to chance events in later life rather than early experience .
5. “The more positive stimuli a baby is given, the more brain cells and synapses it will be able to develop”. (p.57)
The number of brain cells is almost completely genetically determined; neurons are not formed in response to positive stimuli and the baby has a full complement at birth. What the research suggests is that connections between brain cells (synapses) are formed in response to novel sensory information (‘positive’ or otherwise) and are then pruned when those stimuli are repeated, to create robust pathways for processing information that is handled repeatedly. And that synaptic pruning is what is critical for making information processing efficient. People whose synapses are not pruned at the typical rate often have significant learning difficulties .
6. “Trauma also confuses the neurotransmitter signals that play key roles in directing the paths of growing neurons and therefore hinders brain development.” (p.60)
Some neurotransmitters are involved in neuronal migration but no evidence is presented as to how trauma confuses their signals or what deficits occur as a result. The primary role of neurotransmitters is to activate or inhibit neighbouring neurons across synapses.
7. “ To the best of current knowledge, the sensitive window for emotional sensitivity and empathy lies within the first 18 months of life, and these ‘skills’ are shaped by the prime caregiver”. (p.60)
This assertion appears to be based on work by Schore  although there is no attribution in this section. There’s a debate over sensitive or critical periods; they certainly exist for basic visual and auditory processing skills, but windows for other more complex skills are less clear-cut. If there is a sensitive window for emotional development within the first 18 months of life, how is the success of emotional literacy programmes explained and how could early interventions up to the age of 3 years be effective?
8. “Because the infant’s cortical and hippocampal emotional circuits require significant time and experience to mature, the child must regulate its inner world primarily through attachment relationships with primary caregivers. It accomplishes this through aligning its state of mind with that of the caregiver, by establishing a conduit of empathic attunement, functioning as an emotional umbilical chord.
Babies who are healthily attached to their carer can regulate their emotions as they mature because the cortex, which exercises rational thought and control, has developed properly. However, when early conditions result in underdevelopment of the cortex, the child lacks an ‘emotional guardian’.”(pp.61-62)
I think what this passage is trying to say is that prior to the maturation of frontal cortex which plays a significant role in controlling behaviour, infants regulate their behaviour in response to what primary caregivers do. What the passage does say is open to question. It’s unclear what is meant by ‘emotional circuits’; there’s no mention of the significant role of the amygdala in emotional processing; no evidence is cited to support the idea that a child needs to ‘regulate its inner world’ as if through some form of emotional homeostasis, nor to support the idea that a child can do so only via an attachment relationship with a primary caregiver. What exactly is meant by a child ‘aligning its state of mind’ or ‘a conduit of empathetic attunement’ isn’t clear.
9. “Following a 10-year immersion in thousands of scientific papers on neurobiology, psychology and infant development, Alan Schore concluded:
‘The child’s first relationship, the one with the mother, acts as a template that permanently moulds the individual’s capacity to enter into all later emotional relationships’
We glimpse this in the way small children look to a parent’s facial expressions and other non-verbal signals to determine how to respond (and feel) in a strange or ambiguous situation.” (p.62)
Dr Schore has done some impressive work on brain development and emotion, but this statement doesn’t reflect the wide range of factors known to impact on emotional relationships. In fact, all the neurobiological findings cited in Early Intervention: Good Parents, Great Kids, Better Citizens appear to have been filtered through a psychodynamic model of child development, notably attachment theory. The paper also relies heavily on a small number of sources; Bruce Perry, for example, gets 17 mentions (and 11 in Early Intervention: The Next Steps). It’s difficult to avoid the impression that the paper started out with a thesis and then selected evidence to support it.
10. The cover image
The caption for this image says the right hand scan is from a series of three children, but the original source (a paper by Bruce Perry)  says it’s from one child in a group of 40 identified as having suffered global neglect (defined as ‘relative sensory deprivation in more than one domain…e.g. minimal exposure to language, touch and social interactions’). MRI or CT scans were available for 17 of those children, of which 11 were deemed abnormal. It isn’t clear what variation there was within the group, or whether possible genetic causes or environmental causes other than sensory deprivation were investigated. Perry’s team found ‘dramatic differences’ from the average in head circumference. There was ‘some recovery of function and relative brain-size’ after a year in foster care. There were no marked differences between neglected and control groups in the much more common ‘chaotic neglect’ (physical, emotional, social or cognitive).
I don’t doubt that children with minimal exposure to language, touch and social interactions have brains that differ from the norm, nor that they improve in foster care. However, Perry’s analysis raises a number of questions. Healthy, non-neglected children don’t have identical brains (the healthy brain was on the 50th percentile), so why not compare the neglected brain with one at the lower end of the normal range? What type of neglect had the child suffered? Were genetic disorders taken into account? Or diet? Or disease? Does the rate of increase of head circumference change with age? Does it vary between individuals? Although striking, all this particular image actually tells us is that one child who suffered global neglect also had abnormal brain development.
11. “Our responses to situations are not pre-set at birth. The nature/nurture debate has moved on, as was demonstrated in ‘Early Intervention: Good Parents, Great Kids, Better Citizens’.” (p.13)
The nature/nurture debate has indeed moved on, but not quite in the way Good Parents, Great Kids, Better Citizens thinks. See point 3 above.
12. “ Children are born with an instinct to engage socially and emotionally, especially with their mothers. They communicate with the voice, face and hands. They express a curiosity about both the world and their need for comfort and security.” (p. 14)
See points 1 & 2 above.
13. “Recent research also shows insecure attachment is linked to a higher risk for a number of health conditions, including strokes, heart attacks and high blood pressure, and suffering pain, for example from headaches and arthritis. Secure attachment was not linked to any health problems that have been studied.” (p.15)
The validity of attachment theory appears to have been accepted without question. Like many constructs used in psychiatry, ‘attachment’ is loosely defined and difficult to operationalise. Not all children develop patterns of attachment that fit neatly into Ainsworth’s categories, nor are patterns of attachment solely determined by parental behaviour .
I’m also concerned about the conflation of correlation with causation. A correlation between insecure attachment and heart disease, smoking etc. does not mean that they are necessarily linked, or even if they are, it doesn’t follow that insecure attachment is the cause of heart disease, smoking or reckless driving. It could equally well be the case that inherited characteristics that predispose people to heart disease, addictions or risk-taking, via low dopamine levels for example , could also contribute to inadequate parenting.
14. “Although poor parenting practices can cause damage to children of all ages, the worst and deepest damage is done to children when their brains are being formed during their earliest months and years. The most serious damage takes place before birth and during the first 18 months of life when formation of the part of the brain governing emotional development has been identified to be taking place.” (p.15)
The second sentence appears on p.71 of the Munro Review of Child Protection: Final Report, and is attributed to a Royal Society publication Brain Waves Module 2: Neuroscience implications for education and lifelong learning (Munro reference 95) which contains no such statement. Munro’s reference 94 is to Early Intervention: The Next Steps, so the attribution is obviously a typo, but nonetheless the assertion that poor parenting causes ‘brain damage’ is presented here as a matter of fact without any supporting evidence.
15. “Different parts of the brain (governing, for example, sight, hearing, etc) develop in different sensitive windows of time. The estimated prime window for emotional development is up to 18 months, by which time the foundation of this has been shaped by the way in which the prime carer interacts with the child.” (p.16)
See point 7 above. Presumably this claim is based on the same source, but no sources are cited here.
16. “Infants of severely depressed mothers show reduced left lobe activity (associated with being happy, joyful and interested) and increased right lobe activity (associated with negative feelings)19” (p.16)
The Dawson et al. paper (reference 19) is behind a paywall so I couldn’t clarify what is meant by left and right ‘lobes’ and their supposed functions. Presumably this refers to work that suggests the left and right frontal lobes respectively have specialized functions, but this isn’t made clear. Nor is it clear whether the levels of activity in the ‘lobes’ is due to the mothers’ depression or whether mothers and babies share biologically inherited activity patterns.
17. “One result is significantly fewer synapses (or connections). Specialists viewing CAT scans of the key emotional areas in the brains of abused or neglected children have likened the experience to looking at a black hole. In extreme cases the brains of abused children are significantly smaller than the norm, and the limbic system (which governs the emotions) may be 20–30 per cent smaller and contain fewer synapses.” (p.16)
According to Sue Gerhardt in Why Love Matters: How Affection Shapes A Baby’s Brain (her presentation to the Quality of Childhood Group in the European Parliament in December 2009) the ‘black hole’ quote comes from Harry Chugani , and refers to the development of medial prefrontal cortex (MPC) in the brains of Romanian orphans. Here, Gerhardt is talking about the development of the ‘social brain’ (MPC):
“The less attention a baby receives, the less this part of the brain connects up. In the worst cases, like some of the most damaged Romanian orphans, this area of the brain was virtually a black hole according to one researcher, Harry Chugani.” (Gerhardt, p.89)
and illustrates the point using Perry’s image – the one that’s on the cover of the Allen report (Gerhardt, p.88). Although MPC is involved in emotional regulation, it is also involved in risk assessment and decision-making using information from many parts of the brain. It’s not clear whether MPC in the orphans was permanently or temporarily abnormal, or what had caused the abnormality. Genetic, nutritional or infective factors don’t appear to have been controlled for. And a small brain isn’t a bad thing per se; autistic children tend to have larger brains than average, for example. Chugani et al were investigating glucose metabolism in the brain, but Gerhardt doesn’t mention this, so it would be all too easy for people unfamiliar with the technical problems associated with interpreting brain scans to go away with the impression that neglect causes children to develop holes in their brains.
18. “Schore has spoken of ‘the child’s first relationship, the one with the mother, acts as a template … [that] permanently moulds the individual’s capacity to enter into all later emotional relationships’25. ”
“ To attune to a child means responding to their emotional needs, resulting in the child’s sense of being understood, cared for and valued. Empathy begins with the sense of oneness with the other created in this process of attunement. The quality of empathy – the ability to feel for and with another – is not only key to building sound emotional stability, it is also a key inhibitor of the development of a propensity to violence. Conversely, empathy fails to develop when prime carers fail to attune to infants in the first 18 months of life. Absence of such parental attunement, combined with harsh discipline, is a recipe for violent, antisocial offspring. Empathy is influenced very early in life by observed parental reactions to another’s suffering. Even in their first year, children already show signs of whether their reaction to the suffering of another is empathy, indifference or downright hostility.” (p.17)
The quotation from Schore also appears on page 62 of Early Intervention: Good Parents, Great Kids, Better Citizens and is widely cited on the internet, but I couldn’t locate the source; I couldn’t find it in note 25, Schore’s account of the right hemisphere’s role in emotion regulation. There is no question that a child’s early relationships are significant; but no evidence is provided that the relationship with the mother forms a template for all other relationships.
Both Allen and Allen & Duncan Smith papers are about Early Intervention Programmes – the brain development chapters are simply there to add weight to their arguments in favour of the programmes. I haven’t discussed the interventions themselves because I was primarily concerned about the material on brain development. There’s little question that many of the interventions will do some children some good; whether they will address the social problems they are meant to address is another matter. One of the difficulties with social problems is that they are often caused by complex interactions between many factors – so interventions aimed at one or two factors are likely to have only a small effect overall. For example, an evaluation of the Carolina Abecedarian project  shows that mean mental test scores for children improved by less than 10 percentage points and that early gains reduced markedly over time – there was little difference at age 21. Age at the birth of a first child was 19 in the treatment group compared to 17.5 yrs in controls. Differences in academic achievement were larger and were maintained – possibly due to the early language support in the programme leading to improved reading. In short, the programme had a beneficial effect, but whether it made significant inroads into ‘social problems’ is debatable.
What concerned me most about Early Intervention: Good Parents, Great Kids, Better Citizens and Early Intervention: The Next Steps is that neither is based on a systematic evaluation of neurobiological data, with the data themselves providing information about what could be done to reduce social problems. Instead, both papers start from a Freudian framework for child development, without questioning its fundamental assumptions; Allan Schore  is explicit about the direct descent of this framework from Freud via Bowlby’s attachment theory, and I’ve already drawn attention to the shortcomings of attachment theory.
Instead of drawing on our wide range of knowledge about child development as a whole, both papers focus on just one facet of it; emotional development. Furthermore, they focus on one facet of emotional development – attachment; and on one facet of attachment – the child’s relationship with the primary caregiver. The primary caregiver is often implicitly assumed to be the parent, and more specifically the child’s mother – even though fathers, grandparents and siblings are often primary carers and many children have more than one primary carer. This narrow model of child development is supported with often over-simplified and misunderstood neurobiological findings, selected, it appears, because they support the assumptions that the model makes. Findings that do not support these assumptions are simply omitted.
It could be argued, with good reason, that an in-depth analysis of the neurobiological evidence would be beyond the scope of policy papers like these. However, the omission of aspects of child development other than attachment to the primary caregiver is a serious one. It implies that interventions are being proposed on the basis of a belief that they will be effective, rather than on the basis of an evaluation of research evidence across all areas of child development. This introduces a significant risk of interventions failing to eliminate social problems and being abandoned despite some beneficial outcomes for the children involved. A better approach might have been to enlist the help of a developmental neurobiologist for the evaluation of neurobiological evidence, to identify all the reasons why young people fail to reach their potential and to look at interventions which address each reason, including taking a critical look at the efficacy of current healthcare, education and social support systems.
1. National Research Council (2000), From Neurons to Neighborhoods: The Science of Early Childhood Development (Chapter 8), Washington D.C. (available online at http://www.nap.edu/openbook.php?isbn=0309069882)
2. Mareschal, D., Johnson, M., Sirois, S., Spratling, M., Thomas, M. & Westermann, G. (2007). Neuroconstructivism: How the Brain Constructs Cognition, vol. 1. Oxford: Oxford University Press.
3. See e.g. http://en.wikipedia.org/wiki/List_of_reflexes_%28alphabetical%29
4. Thelen, E. & Fisher, D. M. (1982). Newborn stepping: An explanation for a “disappearing” reflex. Developmental Psychology, 18, (5), 760-775.
5. Chen, X., Striano, T. & Rakoczy, H. (2004). Auditory–oral matching behavior in newborns, Developmental Science, 7, (1) 42–47.
6. Pinker, Steven (2002). The blank slate: The modern denial of human nature, Penguin.
7. Cohen, I.L. (2007). A neural network model of autism: implications for theory and treatment. In D. Mareschal, S. Sirois, G. Westermann & M. Johnson (2007). Neuroconstructivism: Perspectives and Prospects, vol. 2. Oxford: Oxford University Press.
8. Schore, A. (2000). Attachment and the regulation of the right brain, Attachment & Human Development, 2 (1), 23–47.
9. Perry, B. (2002). Childhood Experience and the Expression of Genetic Potential: What Childhood Neglect Tells Us About Nature and Nurture, Brain and Mind 3, 79–100.
10. Oppenheim, D., Koren-Karie, N., Dolev, S. and Yirmiya, N. (2009). Maternal insightfulness and resolution of the diagnosis are associated with secure attachment in preschoolers with autism spectrum disorders, Child Development, 80, 519–527.
11. Iversen, L. (2008). Speed, Ecstasy, Ritalin: The Science of Amphetamines, Oxford University Press.
12. Chugani, H.T., Behen, M.E., Muzik,O., Juhasz, C., Nagy, F. & Chugani, D.C. (2001). Local Brain Functional Activity Following Early Deprivation: A Study of Postinstitutionalized Romanian Orphans, NeuroImage 14, 1290–1301.
13. Early Learning, Later Success: The Abecedarian Study (1999). Highlights of the Age 21 Follow-up Study, Chapel Hill: University of North Carolina, FPG Child Development Center. Available at http://fpg.unc.edu/sites/fpg.unc.edu/files/resources/reports-and-policy-briefs/EarlyLearningLaterSuccess_1999.pdf
Image of synapses from Wikipedia.