Journals > Journal: School Readiness: Closing Racial and Ethnic Gaps > Article: Neuroscience Perspectives on Disparities in School Readiness and Cognitive Achievement
Journal Issue: School Readiness: Closing Racial and Ethnic Gaps Volume 15 Number 1 Spring 2005
Kimberly G. Noble Nim Tottenham B.J. Casey
Three Core Neurocognitive Systems
To illustrate how brain development can inform notions of readiness and achievement, we briefly describe three key neurocognitive systems involved in cognitive skills necessary for school success. Cognitive control, the ability to override inappropriate thoughts and behaviors, is associated with the prefrontal cortex, located in the front of the brain. Learning and memory involve the hippocampus, buried deep within the brain's temporal lobe. And reading (and its precursors in preliterate children) is associated with the temporo- parietal and temporo-occipital cortex, located on the left surface of the brain. Each of these brain regions changes and matures throughout childhood, and researchers are currently trying to understand how children's experiences influence such brain development. Scientists hope that this research will lead to insights that are promising for the design of specific educational interventions.
Cognitive Control
Cognitive processes attributed to the prefrontal cortex include the ability to allocate attention, to hold something “online” in memory, and to withhold an inappropriate response.2 Such processes, collectively known as cognitive control, are important developmentally, as they underlie cognitive and social skills essential to academic success, such as the ability to ignore distracting events inside and outside the classroom. In the laboratory, researchers can design behavioral tasks to assess a child's ability to inhibit an inappropriate response. For example, a widely used paradigm known as the Go–No Go task presents a child with many “go” stimuli that require a rote button-press response, along with an occasional “no go” stimulus that requires the child to withhold a response.3
Now, thanks largely to developments in imaging methods, like magnetic resonance imaging (MRI), researchers can study cognitive skills in the developing human brain. More than a decade ago, Kenneth Kwong, Seji Ogawa, and others showed that magnetic resonance is sensitive to blood oxygenation changes in the brain that may reflect changes in blood flow and neuronal activity.4 The discovery that MRI can assess activity in the human brain without the need for radioactive tracers required by other forms of brain imaging opened a new era in the study of human brain development and behavior. Since then, numerous functional magnetic resonance imaging (fMRI) studies have examined children engaged in cognitive control tasks and have found a characteristic age-related pattern in the development of neural activity in the prefrontal cortex.5 In young children, cognitive control tasks are associated with diffuse patterns of prefrontal cortex activity, whereas by adolescence the pattern of activity is both more focal and more intense. In adulthood, activity remains focal, but somewhat less intense. Because increasing age is also linked with accuracy in performing a task, with experience, and with learning, one possible interpretation of these findings is that the age-related decrease in brain activity could reflect reduced recruitment of brain tissue as the task becomes easier. But studies that have matched children and adults on accuracy on the Go–No Go task show that prefrontal activity differences represent maturational change, not difference in ability.6
Memory and Learning
The development of memory and learning is also clearly important to academic success. One aspect of learning is the ability to form new associations among events. In laboratory tasks that test the learning of new memories, children typically see or hear lists of words, stories, or scenes and then try to recollect the presented stimuli.7 For very young children, for whom a nonverbal memory assessment is preferable, researchers first familiarize the child with a stimulus and then present him or her with test trials pairing the familiar stimulus with a new one. Infants' known preference for novelty allows researchers to infer that an infant who spends a longer time looking at the new stimulus recognizes the familiar one.8
The ability to learn and remember is supported in part by the hippocampus, located deep inside the brain's temporal lobe.9 A child's hippocampus increases in size with age, with a particularly sharp increase before the age of two.10 During the course of those two years, a child's ability to learn and remember associations matures in terms of both how much information is remembered and how long it is retained.11 Although research into the link between a child's memory and the functional neuroanatomical development of the hippocampus is still in its early stages, a recent imaging study showed that in both children and adults, the speed of learning a new association was correlated with hippocampal activity.12 Interestingly, as with cognitive control and the prefrontal cortex, the activity associated with forming and remembering new associations was more diffuse and less focal in children than it was in adults.
