Attention and Early Brain Development
Greg D. Reynolds, PhD, John E. Richards, PhD
Department of Psychology, University of Tennessee, USA, Department of Psychology, University of South Carolina, USA
Attention serves several functions related to information processing. It selects certain events or objects in the environment to focus on and maintains focus on the object of interest while information provided by that object is processed. Additionally, while attention is focused on one object, shifts in attention to distracters are inhibited. These aspects of attention show major developmental change throughout infancy.
In infants, attention is thought to change with age concurrently with changes in brain function. Several scientists interested in early cognitive development have proposed neurodevelopmental models of attention development based upon behavioral findings in human infants, integrated with findings related to changes in brain function from studies of non-human animals and human adults, or neuropsychological research on clinical populations.1,2,3,4,5,6,7 Many of these models are influenced by Schiller’s research8 on eye movement systems in non-human primates. In infants from birth to two months of age, it is proposed that eye movements are primarily driven by a “reflexive system” largely under the influence of primitive brain areas located beneath the cerebral cortex (i.e., subcortical). Thus, eye movements and visual attention are generally reflexive in early infancy. Between three and six months of age, a voluntary orienting network becomes functionally mature. This network includes areas within the parietal and temporal cortices and the frontal eye fields and is involved in the ability to voluntarily shift visual attention from one stimulus to another.9,10 From six months on, the anterior attention network (or executive attention system) becomes functional, as areas within the prefrontal cortex and the anterior cingulate cortex begin to play a significant role in maintaining visual attention while inhibiting shifts of attention to distracters.
Infant visual attention and brain development are often studied using “marker tasks.” These are behavioral tasks for which the brain areas involved have been firmly established. Johnson11 has argued that marker tasks can be used to indirectly study brain development in infants and children. However, Richards and colleagues12,13 argue that there are several weaknesses to this approach and that the best solution is to apply direct measures of brain activity. Most of the major approaches to direct measurement of cortical activity (e.g., positron emission tomography, functional magnetic resonance imaging) cannot be used with human infant participants because of ethical and/or practical concerns. We describe a new technique to measure human infant brain activity directly.
Infant attention is measured in the laboratory using looking time, heart rate, and the electroencephalogram (EEG).14,15,16 Briefly, infant heart rate shows a sustained decrease during periods of attention. This decrease in heart rate is triggered by activity within the brainstem. The EEG measures electrical activity that is produced in the brain with electrodes on the scalp. A common approach to research on perception and cognition is to identify event-related potentials (ERPs) in the EEG. ERPs are changes in EEG that are related to a specific event or task. Specific ERP components are identified; these show changes in electrical activity based upon experimental conditions. EEG and ERP data can be further analyzed with multivariate statistical modeling techniques, referred to as Equivalent Current Dipole (ECD) analysis, to determine which brain areas are the likely causes of ERPs measured on the scalp.15,16,17 This provides a more direct measure of infant brain activity involved in attention.
Key Research Questions
The key research questions addressed by this line of work are what areas of the brain are involved in infant attention, whether the areas involved in attention change across the course of infant development and, whether electrophysiological measures of attention are consistent with behavioral measures of attention. Ultimately, all of these questions relate to the need to learn more about brain-behavior relations in infancy.
Recent Research Results
In infant ERP research, a component of the ERP labeled Negative central (Nc) has been found to be more active following presentation of salient stimuli and most likely related to attention.14,18,19 Richards14 found that the Nc component is greater in amplitude when heart rate indicates attention. In a follow-up study, Reynolds and Richards15 found that the areas of the brain involved in the Nc component are located within the prefrontal cortex and the anterior cingulate. Remember that these are areas associated with the executive attention system. The Nc component has been found to increase in amplitude as the infant ages, indicating increased attention-related activity in the prefrontal cortex during infancy.14,20 This parallels increased voluntary control of attention occurring in this age range.21 Recently, we16 designed a procedure that simultaneously measures behavioral responses and infant ERPs. Results showed that infants who prefer to look at a novel stimulus rather than a familiar one show greater Nc activity following novel stimulus presentations than familiar presentations. Those who do not demonstrate novelty preference also fail to demonstrate differences in Nc based upon novelty versus familiarity. Taken together, these findings show consistency between behavioral, heart rate and ERP correlates of infant attention.
Although the application of ECD analysis to infant ERP data represents a major step in measuring attention-related infant brain activity, there is still much room for progress. The parameters used in ECD analyses are based on adult anatomy (e.g., skull and scalp thickness). The infant skull is thinner than that of adults, and the fontanels and skull sutures are not yet completely fused. Richards22 is currently developing a procedure for ECD analyses using parameters based upon the individual infant’s skull and brain matter. However, further progress must be made in designing new procedures to simultaneously measure behavioral and electrophysiological correlates of infant attention. Ultimately, what is needed is a direct, non-invasive measure of infant brain activity that can be practically applied. Until these research gaps are addressed, our knowledge of infant brain activity and brain-behavior relations will remain constrained by methodological limitations.
There is a rich history of behavioral research on the development of attention in infancy. Additionally, several scientists working in the area have proposed models of infant brain development, integrating behavioral findings from infant research with research on brain development in animals and adults.1,2,3,4,5,6,7 While many of the models proposed by such scientists may accurately describe the progression of infant brain development in relation to attention, at present the models remain untested because of methodological limitations. However, major progress has been made, and we now know that there is consistency between commonly used behavioral, heart rate and electrophysiological correlates of infant attention.14,16 We have made an initial step in identifying areas of the brain related to cognitive development by demonstrating that areas of the prefrontal cortex and the anterior cingulate are involved in infant attention.15 Many questions remain unanswered and limitations unaddressed. We are confident that steady progress will continue in research on infant brain development and attention.
One of the major implications of research on infant attention relates to attention deficit hyperactivity disorder (ADHD). It is currently estimated that ADHD affects from 5 to 10% of school-aged children.23 Symptoms of ADHD include poor control of attention, inattentiveness, hyperactivity, poor impulse control and behavior management problems. Evidence indicates that the inattentive aspect of ADHD may be related to deficits in the voluntary orienting network, whereas the hyperactive aspect of ADHD may be related to a poorly functioning executive attention system.24 The executive attention system involves the prefrontal cortex and anterior cingulate, areas identified as sources of attention-related cortical activity in our research on infant attention.15 ADHD is typically not apparent in affected children until the school years. These children may be referred to health-care professionals for problems controlling their behavior in classroom settings. It would be ideal to have an earlier identification method for children at risk of developing ADHD. The promise of basic research on infant attention and brain development is the potential identification of atypical patterns of infant development that may predict later onset of ADHD.
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- Colombo J. On the neural mechanisms underlying developmental and individual differences in visual fixation in infancy: Two hypotheses. Developmental Review 1995; 15(2):97-135.
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- Johnson MH. Cortical maturation and the development of visual attention in early infancy. Journal of Cognitive Neuroscience 1990;2(2):81-95.
- Maurer D, Lewis TL. Overt orienting toward peripheral stimuli: Normal development and underlying mechanisms. In: Richards JE, ed. Cognitive neuroscience of attention: A developmental perspective. Hillsdale, NJ: Lawrence Erlbaum Press; 1998, 51-102.
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- Schiller PH. A model for the generation of visually guided saccadic eye movements. In: Rose D, Dobson VG, eds. Models of the Visual Cortex. Chichester, NY: Wiley, 1985: 3-50.
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- Richards JE. Attention in the brain and early infancy. In: Johnson SP, ed. Neoconstructivist views on infant development. In press.
- Richards JE, Hunter SK. Testing neural models of the development of infant visual attention. Developmental Psychobiology 2002;40(3):226-236.
- Richards, JE. Attention affects the recognition of briefly presented visual stimuli in infants: An ERP study. Developmental Science 2003:6(3):312-328.
- Reynolds GD, Richards JE. Familiarization, attention, and recognition memory in infancy: An ERP and cortical source localization study. Developmental Psychology 2005;41(3):598-615.
- Reynolds GD, Courage ML, Richards JE. Infant visual preferences and event-related potentials. Submitted for publication.
- Reynolds GD, Richards JE. Cortical source localization of infant cognition. Submitted for publication.
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- Webb SJ, Long JD, Nelson CA. A longitudinal investigation of visual event-related potentials in the first year of life. Developmental Science 2005;8(6):605-616.
- Courage ML, Reynolds GD, Richards JE. Infants’ attention to patterned stimuli: Developmental change from 3 to 12 months of age. Child Development 2006;77(3):680-695.
- Richards JE. Realistic source models of ERP data. Unpublished manuscript, 2006.
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- Aman CJ, Roberts RJ, Pennington BF. A neuropsychological examination of the underlying deficit in attention deficit hyperactivity disorder: frontal lobe versus right parietal lobe theories. Developmental Psychology 1998;34(5):956-969.
How to cite this article:
Reynolds GD, Richards JE. Attention and Early Brain Development. In: Tremblay RE, Boivin M, Peters RDeV, eds. Paus T, topic ed. Encyclopedia on Early Childhood Development [online]. http://www.child-encyclopedia.com/brain/according-experts/attention-and-early-brain-development. Published December 2008. Accessed December 13, 2017.