Presentations

We have presented some of the data we have gathered in the "Cognitive Event-Related Potentials and Brain Maturation: A Developmental Study" project and our other research efforts as poster presentations at several conferences. A summary of the poster presentations and the posters themselves can be found via the following links:

Developmental Trends in Sensory Gating Measured in Young Children

poster

Abstract: Sensory gating can be measured by using a paired-click event-related potential (ERP) paradigm. Sensory gating has been found to be impaired in adults with schizophrenia (e.g., Nagamoto, et al., 1989; Olincy, et al., 2000). A growing interest in measuring sensory gating in children has necessitated finding a valid method for collecting these data in young children (e.g., Myles-Worsley, et al., 1996). We recorded ERPs from 22 children, ages 4 to 11 years, in two conditions; 1) sitting quietly while listening to paired clicks (auditory only), and 2) watching a silent movie while listening to paired clicks (auditory+movie). We examined sensory gating by evaluating changes in the P50 and N100 components using a ratio of the amplitude of the test click to the amplitude of the conditioning click. While over 73% of the children displayed sensory gating in at least one condition (T/C ratio < .80), there was not a significant correlation between the 2 conditions measured at Cz. Differences between the mean T/C ratios of the two conditions for the P50 and N100 for were not significant because of large within group variances. These results are similar to previous studies showing that sensory gating is not consistently observed in children using traditional ratio measures (e.g., Freedman, et al., 1987). A developmental trend was found in the auditory only condition where N100 suppression significantly correlated with age.

Click here to view the complete copy of this poster in PDF format.

top


Development Of Error Monitoring Erps In Adolescents

poster

Introduction: In a target discrimination task, trials with incorrect responses elicit event-related potentials (ERPs) that include an error-related negativity (ERN) and a later error-positivity (Pe). Substantial evidence points to the anterior cingulate cortex (ACC) as the source generator of the ERN. The ACC is involved in executive functions with major connections between the prefrontal cortex (PFC) and limbic system. Given the continued maturation of the ACC, PFC, and domaminergic systems into young adulthood, our aim was to investigate the development of ERPs to correct and incorrect (error) responses. Methods: ERPs to correct and incorrect responses were recorded during a standard 480-trial visual flanker task in 124 children, 7 to 18 years of age, and 27 adults, 19 through 25 years of age. The electroencephalogram (EEG) was recorded from twenty-nine scalp sites. Results: The linear and quadratic age effects in the ERN were significant and accounted for 20% and 10% of the variance in the ERN. The clear reduction in ERN amplitude at age 10 years and subsequent fluctuations through adolescence are suggestive of pubertal effects, so we examined the interactions with gender. The Age x Gender interaction was significant. The ERN quadratic distribution indicated an initial drop in amplitude with a subsequent rise through adolescence. The girls have a minimum value at age 10 years while for the boys the lowest value is at age 13 years. The Pe amplitude did not change with age. Conclusion: The data presented here support a continued physiological maturation of the ACC and its connections with the PFC through adolescence given that the ERN is generated in the ACC and develops into adolescence, not reaching adult levels until late teen years. This contrasts with the development of the Pe component, found to be very robust even in the young children.

Click here to view the complete copy of this poster in PDF format.

top


Concurrent Change in Electrophysiology and Functional Performance of the Prefrontal Cortex from 7 to 25 years

poster

Summary: We examined the relationship between changes of the Contingent Negative Variation (CNV) and functional changes in performance on 15 behavioral tasks (9 associated with executive functions, 6 with nonexecutive functions, plus estimated IQ). A total of 165 participants (27 adults 19-25 y and 138 children 7-18 y) performed a CNV paradigm with 40 Go and 40 Nogo trials. Average amplitude of the CNV 800-2000 ms epoch on Go trials correlated with age (r = -.54, p<.0005). Similarly, almost all the behavioral tasks correlated with age (r = .23 - .79, p<.005). In order to see which aspects of cognitive performance are specific to CNV independent of age, we correlated CNV with performance partialling out age. This produced significant correlations between CNV and working memory (1-back, 2-back, and dual task), word recall, vocabulary, and some measures of perceptual-motor speed, but no evidence of correlation with measures of simple attention (Digit Span) or perception (line orientation). Stronger effects are found when the correlations are restricted to subjects in the younger age ranges. This suggests that there are factors other than age influencing CNV amplitude in preadolescents and adolescents. The CNV has been associated with generators in the prefrontal cortex, and present results support the construct of the CNV reflecting good performance of functions associated with this region, replicating earlier work that did not include such a broad age span.

Click here to view the complete copy of this poster in PDF format.

top


Error-related negativity (ERN/Ne) in Children and Adolescents

poster

Summary: The error-related negativity (ERN or Ne) is a negative ERP component seen in error trials that is most prominent when the ERPs are time-locked to the response. Previous work has shown that it is greater in OCD patients, is diminished in individuals demonstrating more impulsive responding, and is reduced in certain contexts amongst individuals very low in socialized beliefs. Dipole localization identifies the anterior cingulatecortex as the physiological generator. The ERN has been reported as diminished in the elderly but we have seen no reports of the ERN in childhood. We examined the ERN in 48 children (7-16 y) and 17 young adults (19-25 y). The ERN was recorded during a standard 480-trial visual flanker task. The ERPs were time-locked to response and the ERN amplitude and latency were scored in error trials. Age correlated strongly with correct RT (-.73, p<.001), incorrect RT (-.67, p<.001) and with the difference (-.29, p<.02, calculated by linear regression; see Pailing et al, 2002, Psychophysiology). Age correlated significantly with ERN amplitude (r=-.35, p=.005) and latency (r=.32, p=.01) only at Cz and not at Fz and Pz. Thus, the ERN is attenuated in children and the latency increases with age. The latter finding is consistent with reduction in response latency and impulsivity with age. Individual differences indicate that despite the children's attenuated ERN amplitudes, some children at each age level have adult-like ERNs.

Click here to view the complete copy of this poster in PDF format.

top


Development of the Contingent Negative Variation (CNV) in Children and Adolescents

poster

Summary: The Contingent Negative Variation (CNV) paradigm consists of a warning stimulus followed by a target (imperative) stimulus at a known interval requiring a response. In adults, the CNV ERP component is generated leading to the second stimulus. Motivation, expectancy, attention and alertness have been shown to affect CNV amplitude. Previous studies strongly implicate the dorsolateral prefrontal cortex as the physiological generator, and executive functions have been shown to correlate with the initial portion of the CNV in various groups. The few studies on children's CNV report that it is less developed in children, but typically include only older children (11 and 12 y) and have not looked at the development across childhood. We examined the CNV in 32 children (7-16 y) and 16 young adults (19-25 y) in a standard CNV paradigm with 2 s SOA between stimuli (40 Go and 40 Nogo trials) and variable inter-trial intervals (2 - 7 s). Average amplitude was measured in several epochs (400-800, 800-1200, 1200-1600,1600-2000, 800-2000 ms) following the warning stimulus. Age correlated significantly with CNV amplitude for all epochs at Cz for Go trials (-.39, -.48, -.37, -.43, -.45, all p < .01 for the 5 epochs) and much less so or not at all at Fz and Pz. The Nogo trials do not correlate with age for any of the epochs or sites. Thus, the negativity of the Go trials increases with age but children's EEG is similar to adults on the Nogo trials.

Click here to view the complete copy of this poster in PDF format.

top


ERPS and Neuropsychological Tasks Show Prefrontal Maturation In Adolescents

poster

Summary: We examined the relationship between changes of the Contingent Negative Variation (CNV) and functional changes in performance on 15 behavioral tasks (6 associated with "prefrontal" functions, 8 with "posterior" functions, plus estimated IQ). Forty-three participants (12 adults 19-25 y and 31 children 7-16 y) performed a CNV paradigm with 40 Go and 40 Nogo trials. Average amplitude of the CNV on go trials correlated with age (r= .44, p=.003). Similarly, almost all the behavioral tasks correlated with age (r=.49-.84, p<.001). In order to see which aspects of cognitive performance are specific to CNV independent of age, we correlated CNV with performance partialling out age. This produced significant correlations between CNV and working memory (2-back), word recall, Stroop interference, vocabulary, and some measures of perceptual-motor speed, but no evidence of correlation with measures of simple attention (Digit Span) or perception (line orientation). Stronger effects are found when the correlations are restricted to subjects in the younger age ranges. This suggests that there are factors other than age influencing CNV amplitude in preadolescents and adolescents. The CNV has been associated with generators in the prefrontal cortex, and these results support the construct of the CNV reflecting good performance of functions associated with this region, replicating earlier work that did not include such a broad age span.

Click here to view the complete copy of this poster in PDF format.

top