Interaction and the Architecture of the Brain

By Dorian Friedman

Abstract: Recent advances in developmental science can teach us a great deal about the value of specific kinds of human interactions in the earliest years of life for the developing brain architecture. Animal experiments indicate that enriched environments with opportunity for frequent interaction and new experiences can help the animals’ brains develop more healthy connections. Similarly, when adults engage in give-and-take interaction with babies, it provides a solid foundation for social, emotional, and self-regulatory development. The value of such interaction with a wide range of loving, attentive adults in the family and beyond pays indisputable dividends for the child later in life. Using this science to inform public policy could shape what we emphasize to ensure quality child care and early childhood education, how we structure parental leave policies, and how we break the cycle of poverty.

For as long as humans have walked the earth, our interactions with others have helped to shape who we are. But only in recent years have we begun to understand how the most basic forms of human interaction and early experience mold the developing brain’s architecture to profoundly influence who we become. The calculus is surprisingly simple, given the complex world of neuroscience: Nurturing, positive interaction releases chemicals in a child’s brain that promote its growth and development, while negative influences produce chemicals that weaken its architecture. (For a detailed review of the latter subject, please see the new article, “Stress and the Architecture of the Brain.”)

Developmental science teaches us a great deal about the negative consequences for brain development resulting from harmful environments and other conditions that might pose dangers to the growing brain. It teaches much less about how we can alter the natural wiring process of children’s brain development. Even so, an ever-growing body of research demonstrates the remarkable extent to which nurturing environments and positive interactions build healthy brain architecture. That research—and the public-policy implications arising from it—animates the work of the National Scientific Council on the Developing Child.

Learning from Animal Research

Much of what we now know about the powerful links between early experience, interaction, and the developing brain comes from the study of animals. Among the more compelling findings are those from the Council’s William Greenough, a veteran neuroscientist at the University of Illinois at Urbana-Champaign. Over the years, Greenough and his colleagues have studied two groups of rats: one group reared alone or in bare cages, the other housed in the “luxury condo” equivalent of a lab cage, containing some combination of play equipment, challenging games and obstacle courses, and—importantly—other animals.

Greenough’s team has found that the condo dwellers—those from more complex or “enriched” environments, with lots of opportunity for interaction and new experiences—actually develop measurably different brains, with architecture that is both stronger and more intricate. These animals have more neurons, the brain’s basic nerve cells, than do rats lacking stimulation. Their neurons sprout more and stronger synaptic connections.

And their brains produce more glia (from Greek, for the “glue” that holds things together), which are the brain cells that surround neurons and synapses. Glia carry vital nutrients, blood and oxygen and promote healthy neuronal function. “And that,” notes Greenough, “may be the most important point. If the animal’s early interaction is happy, stimulating and nurturing, there will be more of these cells that provide buffering and protective qualities to the brain.” This enhanced brain architecture confers great benefits to the animals that possess them.

In lab tests, the “enriched” rats outperformed others on a variety of learning and problem-solving tasks, leading researchers to conclude that a sturdy early foundation for brain architecture—and, specifically, one that produces a multitude of new synapses—supports learning and memory. Moreover, research like this offers another important lesson. Everything we know about the brain tells us that it is most malleable (or has the greatest plasticity, in the parlance of neuroscience) in the earliest years of life. That fact is demonstrated yet again in these experiments: Rats raised from infancy in the challenging environments showed the fastest and most dramatic gains in brain architecture. However, it wasn’t too late for their older peers: Rats moved to the enriched cages as full-grown adults also benefited from the extra interaction and stimulation, and had demonstrably stronger brains and better performance levels than rats raised elsewhere. The exciting conclusion, say experts: The brain’s capacity to grow and fortify itself in response to new challenges and learning is a lifelong property, not something lost at an early age.

From Rat Cages to the Human Brain: How Interaction Matters

Can the stimulating environments and positive interaction that build brain complexity in lab rats be marshaled to benefit our own children? And what’s the environmental equivalent of the rats’ luxury condo when it comes to human enrichment? A growing body of science—including the rapid evolution of sophisticated brain-imaging technology—does hint at the amazing ways in which a child’s brain architecture grows stronger and more complex, with more neural connections, as a result of exposure to stimulating environments and new challenges. Still, experts caution that much more research is needed before we understand the full causal relationship between early experience and the physiology of the human brain.

For information about commonly used terms in Council publications, see Definitions.