The Effects of Poverty on Brain Function in Children Mark M. Kishiyama

Socioeconomic Disparity Strong associations have been found between socioeconomic status (SES) and cognitive ability and achievement in childhood: Strong associations have been found between socioeconomic status (SES) and cognitive ability and achievement in childhood:  Low SES (LSES) children perform below children from higher SES backgrounds on tests of intelligence, language proficiency, and academic achievement (Bradley & Corwyn, 2002; Duncan et al., 1994).  LSES children are more likely to fail courses, be placed in special education, and drop out of school compared to high SES (HSES) children (McLoyd, 1998).

Socioeconomic Disparities & Prefrontal Function Behavioral findings indicate that socioeconomic disparities disrupt prefrontal function in children   LSES children have reduced performance on cognitive tests including those of executive function compared to middle SES children (Farah et al., 2006).   LSES children are impaired on measures of alerting and executive attention compared to HSES children (Mezzacappa, 2004).

Socioeconomic Disparities & Prefrontal Function Behavioral tests of prefrontal function have a number of limitations:   Correlations among these tests are low.   They vary in complexity such that it is difficult to separate task difficulty with frontal dysfunction.   They provide only indirect measures of prefrontal function.

Scalp EEG Scalp EEG is the measurement of electrical activity of the brain as recorded by electrodes placed on the surface of the scalp. Scalp EEG is the measurement of electrical activity of the brain as recorded by electrodes placed on the surface of the scalp.

Event Related Potentials (ERPs) Electrophysiological correlates of brain activity time locked to cognitive events

Socioeconomic Disparities & Prefrontal Function Predictions:   Differences would not be observed between LSES & HSES children in either behavioral or ERP measures (P3b) of target detection   LSES children would have reduced extrastriate (P1 & N1) and novelty ERP (N2) responses compared to HSES children   These patterns have been observed in patients with lateral prefrontal cortex (PFC) lesions (Barcelo et al., 2000; Knight, 1984; Knight, 1997).

Socioeconomic Disparities & Prefrontal Function Yago, et al. (2004) Cognitive, Affective, & Behavioral Neuroscience

Method Participants:   26 child subjects (13 High SES, 13 Low SES; mean age 9.5 years) recruited from the San Francisco Bay Area   Child subjects had no history of neurological or psychiatric disorders, drug abuse, or prenatal exposure to drugs or alcohol.   SES was determined by primary caregiver education, average family income, & income-to-needs ratio.

The Novelty Oddball Paradigm

EEG Recording   EEG signals were continuously recorded from 64 channels with two reference electrodes   EEG signals were amplified and digitized using a 512 Hz sampling rate   ERPs were computed from artifact free data epochs extending from 100 ms prior to 1000 ms post-stimulus onset

Behavioral Results Target behavioral responses did not differ across the two groups in either RT or hit rate accuracy Kishiyama, et al. (2009) Journal of Cognitive Neuroscience

ERP Results Target Stimuli

ERP Results Target Stimuli

ERP Results Standard Stimuli

ERP Results Standard Stimuli

ERP Results Novel Stimuli

ERP Results Novel Stimuli

Neuropsychological Test Results Neuropsychological tests revealed that LSES children had reduced performance compared to HSES children on tests of executive function.   These tests index cognitive processes associated with the PFC (Diamond, 1988; Goldman-Rakic, 1987)   These results are similar to prior studies that found reduced performance in LSES children on executive tests (Farah et al., 2006; Noble et al., 2005)

Conclusions The behavioral & electrophysiological results of this study indicate that factors associated with social inequalities contribute to altered prefrontal function in LSES children.

Conclusions Major stages of cognitive development are associated with the development of the PFC Experience can affect brain development   Environmental complexity can augment brain development (van Praag et al., 1996)   Environmental deprivation & stress adversely affect PFC development in animals (Braun et al., 2000; Poeggel et al., 1999).   Stressful rearing conditions have been found to predict behavior more reliably than genes (Francis et al., 2003)

Conclusions   LSES children have limited access to cognitively stimulating materials and experiences and they receive less attention from adults than higher SES children (Bradley & Corwyn, 2002; Hart & Risley, 1995).   LSES children are exposed to greater numbers of chronic stressors and they tend to live in more stressful environments than higher SES children (McLoyd, 1998)

Conclusions Identifying specific prefrontal processes affected by social inequalities could be helpful in developing intervention programs for LSES children   Intervention programs have been found to improve both the intellectual development & academic achievement in at-risk children (Belfield et al., 2006; Ramey et al., 1999)   Targeted intervention improved executive function skills in LSES preschool children (Diamond et al., 2007).

Acknowledgments WINKS group: Khaled Sarsour Doug Jutte Margaret Sheridan Amani Nuru-Jeter Abbie Rakes Bob KnightTom Boyce Michael PerryAmy Jimenez