What is Neuroscience Telling Us about Babies?
An Interview with Charles Nelson, Ph.D.
Recently, I had the honor of sitting down with Dr. Charles Nelson, Professor of Pediatrics at Harvard Medical School, to discuss the nature of his research in Developmental Cognitive Neuroscience and his thoughts about how Neuroscience is advancing the fields of infant research, education, intervention and prevention.
Dr. Nelson's background and training reflects a wide range of interests and disciplines. As a teenager, Dr. Nelson expressed interests in the fields of child psychology and astronomy. His interests in child psychology originated from his personal desire to understand his own relationship with his parents and how early experience shapes children. Astronomy, in his words, "has overlapping interests in discovery", but recognizing his limitations in mathematics, he decided to pursue a degree in Psychology as an undergraduate at McGill University. There, Dr. Nelson worked directly with a former student of Donald Hebb (a world-renowned leader in the field of Neuropsychology) and was able to follow his interest of how early experience affects children. Additionally, he was also able to explore a new emerging field - neuroscience.
Still, Dr. Nelson felt compelled to study children, forsaking neuroscience, and continued his education in Child Psychology at the University of Wisconsin where he acquired a Masters degree working in a baby lab examining infant speech perception. It was during this time, that Dr. Nelson more specifically realized his love of babies and embarked on a doctoral degree in Child Developmental Psychology at the University of Kansas.
Alongside his laboratory work, Dr. Nelson worked with children with severe learning and behavioral disabilities in Ontario, Canada. He recounts a personal story about a confrontation with one particular child who was angry with him and actually "threw a rock at him". He was afraid but the child was unable to interpret his facial expression of fear. It was after this experience that Dr. Nelson became intrigued with why some children are unable to read facial signals. More specifically, he wondered about the origins of the ability to process facial expressions, which brought him back to his undergraduate focus on the brain.
Upon completion of his doctoral degree, Dr. Nelson was still not sure about the best way to study the brain in children. So, when searching for a postdoctoral fellowship, he chose the University of Minnesota, Institute of Child Development because of its long tradition of training in Developmental Psychology, but even more so for its innovative research techniques, which measured babies' brain wave patterns. At last, this enabled him to fuse his two interests– infant psychology and the study of brain; he then went on to complete completed his training in electrophysiology.
Since then, Dr. Nelson continues to conduct research on the factors that influence children's brains. He acknowledges that a portion of his neuroscience expertise is self-taught and/or the result of generous mentorship from colleagues (as well as co-authoring a major college textbook on neuroscience). He is lighthearted, disclosing that in his early years he lacked a strategic plan and specific blueprint for the future, but that in hindsight, his interests and goals merged, creating a wonderful marriage between neuroscience and psychology, and more recently, pediatrics.
Q. How would you describe the work you do today? Can you describe some of the research projects you are conducting in your laboratory?
A. I am a Developmental Cognitive Neuroscientist. I am interested in the intersection of brain development and cognitive development. The difference between me and others working in cognitive neuroscience is that most of them are "imagers" (focused on brain scans), but if I am going to examine the manifestation of brain processes like electrical activity or metabolic activity, then I need to understand what factors influence the brain.
There are several strands to my work. In one regard I am revisiting my initial interests in early experience, by conducting a randomized-clinical trial looking at the effects of institutionalization on brain and behavioral development in Romania. The study has been ongoing for a decade. In an effort to go beyond the expected results that children in institutions don't thrive as well as non-institutionalized children, we developed a very high quality foster-care intervention program to examine what types of interventions might provide a beneficial alternative care setting for orphans. We conducted an extensive assessment of children who were abandoned at birth and were placed in an institution. Using random assignment, we conducted a longitudinal comparison of children's behavior and development, by comparing a sample of children who were placed in foster care with a comparison group of children who remained in an institutionalized setting. We are currently waiting to receive word from the NIH whether we will receive funding to examine these same groups of children as they transition to adolescence.
In another regard, I am working in two other fields: the development and neural basis of face processing and the development of memory. In both strands of work, typical development, atypical development, or risk for atypical development is considered. With face processing, we do a lot of work trying to understand how the ability to process information and faces develops by race, gender, age, and species. But, more recently, I am spending time examining face processing among children with autism. One of the features of autism is a deficiency in social communication and impairment in face processing. Another hallmark feature is language impairment. One particular study that I am involved with includes infants at risk of developing autism. The general prevalence of autism in the general population is 1 in 150. If an infant has an older sibling with autism, that rate of the infant developing autism is approximately 1 in 5. So, as you can see it's a genetically informed study; the sample includes 3 to 36- month-old infants who have at least one older sibling with autism, infants who have no family history of autism, and infants who have a sibling with language impairment. We follow these infants longitudinally (every two months) until they are 3-years-old. We are trying to distinguish the infants that develop problems in language from those who develop autism. In collaboration with Helen Tager-Flusberg at Boston University, we conduct standardized measures and EEGs, with the entire sample to assess psychological, cognitive, social, and brain function. We know that children with autism show reduced Gamma activity which is responsible for integrating information across diverse regions of the brain. In a sense, these brains can't talk to themselves. We want to know if there is evidence of this type of reduced brain activity before symptoms of autism present. We think we have an endophenotype or marker for the disorder that can distinguish the high-risk from low-risk infants at 3 months of age. But will these brain measures predict who gets autism? This is the question our research is currently exploring. Obviously the clinical implications here are great.
With regard to my memory research, I am examining infants who have been deprived of blood and/or oxygen at birth and whose brain has been mildly to moderately affected as a result of this injury. This mild brain injury places these infants at risk for memory problems early in life, and presumably, learning problems later in life. These children do not demonstrate any frank neurological features like seizures. Our goal is to better understand learning disabilities and whether an injury such as this that causes deficiencies in memory will contribute to difficulties in learning.
Q. Do you have additional research interests that you have not yet had the opportunity to explore? What's next on your agenda?
A. Oh yes! Conceptually, theoretically, and empirically. Theoretically, I'm very interested in neuroplasticity. I would like to understand more about how the brain adapts positively or negatively to experience. For example, if we understand what brain circuits are impacted by autism and what behaviors are served by those circuits, we should be able to develop an intervention that can target infants at 3 or 6 months of age and if we do it right, then the infant will never develop autism, making it a prevention strategy. In order to do this, we need to understand neural architecture and the brain's malleability to adapt to new experiences. The big questions still for me are: What is the nature of the experience that needs to drive development? When does the experience need to occur? What's the sensitive period for it?
On the empirical side, I'm obsessed with the expression of fear. By 7 months, infants look longer at the facial expression of fear than any other emotion, and they show larger brain responses to fear. I want to know what is developing at this time and why fear? Interestingly, it turns out that children with autism display a different phenomenon- in a task that requires infants to shift their attention from an emotional face to a distractor stimulus presented off to the side, infants at risk for autism disengage just as quickly from a fearful expression as any other expression, whereas low-risk infants disengage much more slowly to fearful faces (as though fear is occupying all their attentional resources). So, my question is "why is the behavioral and neural response to fear different in children at-risk of developing autism?"
Q. How does your work apply to newborn/infant attachment?
A. The autism research I'm doing and the work in Romanian orphanages applies to attachment. We know that children with autism develop attachment, but we are still exploring how do they really differ and how early do they differ from typical children. It's been reported retrospectively by parents of children with autism that by 6-12 months, children become disinterested in faces. A responsive caregiver will adapt to the needs of the child and as a result, disengage from the child because of their disinterest. In fact, this is the wrong thing to do. Thus, how is the caregiver-child relationship impacted by the signals that babies send? In Romania, we know that psychosocial deprivation has an enormous impact on attachment. Our research has shown that when we moved orphans into our high quality foster care intervention before 2 years of age, their attachment behavior improved dramatically compared to children who remained institutionalized. Reactive attachment disorders declined immensely. We didn't find the same results after 2 years of age, telling us there is a sensitive period for attachment and intervention.
Q. Given emerging Neuroscience research and findings, is there a role for behavioral research in the future? How do you believe the two fields should align?
A. Brain activity not grounded in behavior is meaningless. Just looking at images from EEGs and MRI don't tell me what you're thinking, feeling, or doing. Neuroscientists know that brain activity is the substantiation of behavioral processes. We have found that Romanian orphans have approximately an 18-20% prevalence of ADHD. Moving children to foster care does not appear to impact these rates. Why is this the case? One hypothesis is that the brain circuits that bring about ADHD are built very early in development (before 20-22 months) and they are very difficult to change. It is possible that rates do not decline among children in foster care because we passed the sensitive period for this type of brain development, but we must still ask why the high prevalence of ADHD? Addressing this question is currently occupying a good deal of our attention.
There has been some resistance to blending the work of neuroscience with child psychology, but I think there needs to be more of an awareness of the science behind Developmental Psychology to keep folks grounded. The infancy field has been more welcoming of neuroscience. Perhaps, because the field began from a more empirical science. Regardless, all the fields need to work hand-in hand. I think that with the growing numbers of experts in the field of Neuroscience, it is emerging as a valuable addition to the work of Psychologists and other infant mental health professionals.
Q. What is the next frontier in infancy research?
A. Genetics. Molecular genetics has made major advances and research is for the first time affordable. I think as molecular genetics becomes easier to do, it will get embedded in the work of those interested in early development. There are more and more researchers examining gene-environment interactions. I think prevention is likely to benefit most from this new direction. Intervention may also benefit. It may be that certain genetic variants either facilitate or make impossible certain forms of neural plasticity. Most geneticists just want to find genes, like the gene for autism. I want to know where those genes get expressed in the brain, when, and under what conditions. There are others like me. Some of the most interesting work is in the field of epigenetics.
Q. How do you think your work informs clinical providers working with infants and researchers alike?
A. One lesson from our work in Romania is that children before the age of two have sensitive periods for attachment as well as IQ. That said, we should pay attention to sensitive periods, but remember that they are NOT critical periods. In other words, we should not feel hopeless about the trajectory of children exposed to adverse experiences after 2 years, but only be aware that change will be more challenging.
I think that many academics that do basic research shy away from the policy or clinical implications of their work. Yet, I think we have an obligation to have a dialogue with both practitioners and policy makers. I have been involved for years with the National Scientific Council on the Developing Child which came about because there was a need to share what we know about brain development in the first years of life and translate it to policy makers. I think this need still exists. We haven't reached practitioners, and yet neuroscience has implications for educators and specialists working with children with special needs. Those doing applied work in the field need to stay abreast of the science in the field because there are a lot of intervention approaches being utilized based on "bad science." I think the message is that we need to keep communication open and ongoing among basic science researchers, policy makers and practitioners.
I wish to personally thank Dr. Nelson for the generosity of his time and willingness to share his work and expertise during this interview. His commentary is truly insightful to clinical professionals working with infants and families and academic professionals working to advance the field of infancy research.