Margaret Livingstone, PhD ’81, Takeda Professor of Neurobiology
Early life experience has long-lasting consequences on the adult brain’s ability to process and respond to information in the environment, yet how the timing of such experiences can influence the adult brain remains unclear. Understanding the means by which events during early brain development impinge on the adult brain has important implications for both education and health. The timing and quantity of early social experience, for example, may be critical in the cause and remediation of social deficits in Autism Spectrum Disorders, as the core symptoms of the disorder are presented during early life yet permanently impair patients’ social interactions throughout their life.
I study how nature and nurture cooperate to instruct the formation of domains in the brain, areas that specialize in processing particular kinds of information. For example, within a particular species, most adults have domains in the temporal cortex region of the brain that are specialized for processing biologically important categories, like recognizing faces and bodies. There are also regions for processing “un-natural’ or cultural categories, such as writing text and buildings.
The fact that people usually have prolonged and intensive early exposure to faces and writing, prompted us to ask how such experience interacts with hard-wired genetic programs to generate specialized brain modules.
Specifically, we asked whether intensive early experience could lead to the development of domains that would not be naturally used, such as writing for a non-human animal. Our experiments showed that in juveniles, intensive experience associating human writing symbols with reward value resulted in the development of novel modules in a part of the brain usually tasked with object recognition, the inferotemporal cortex. Intriguingly, when we performed similar experiments with older animals, such training did not lead to the formation of writing modules in the brain. This suggests that the timing of experience is a critical component when it comes to the development of specialized processing centers in the developing brain. This work clearly demonstrates that the age of learning must be considered when designing educational curricula, and when it comes to the design of cognitive interventions in disease.
In addition to these experiments, our work has implications for the understanding of how visual experiences affect the developing visual system. Understanding how this system is shaped by experience has had important effects on the medical treatment of congenital cataracts and especially with the condition called strabismus, which is a muscle imbalance resulting in eye turn. Our work should lead to a deeper understanding of the importance and irreversibility of early social and educational experience—and deprivation—on more complex visual and cognitive computations performed by the brain.