The Effects of Poverty onBrain Function in Children

Mark M. KishiyamaMark M. Kishiyama

Socioeconomic Disparity

• Strong associations have been found between Strong associations have been found between socioeconomic status (SES) and cognitive ability socioeconomic status (SES) and cognitive ability and achievement in childhood:and achievement in childhood: Low SES (LSES) children perform below children Low SES (LSES) children perform below children

from higher SES backgrounds on tests of intelligence, from higher SES backgrounds on tests of intelligence, language proficiency, and academic achievement language proficiency, and academic achievement (Bradley & Corwyn, 2002; Duncan et al., 1994).(Bradley & Corwyn, 2002; Duncan et al., 1994).

LSES children are more likely to fail courses, be placed LSES children are more likely to fail courses, be placed in special education, and drop out of school compared in special education, and drop out of school compared to high SES (HSES) children to high SES (HSES) children (McLoyd, 1998).(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 Scalp EEG is the measurement of electrical activity of the brain as recorded by electrodes placed on the surface of the brain as recorded by electrodes placed on the surface of the scalp. 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 groupsin either RT or hit rate accuracy

Kishiyama, et al. (2009) Journal of Cognitive Neuroscience

ERP ResultsTarget Stimuli

ERP ResultsTarget Stimuli

ERP ResultsStandard Stimuli

ERP ResultsStandard Stimuli

ERP ResultsNovel Stimuli

ERP ResultsNovel 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: WINKS group:

Khaled SarsourDoug JutteMargaret SheridanAmani Nuru-JeterAbbie Rakes

Bob Knight Tom Boyce Michael PerryAmy Jimenez