[Abstract Title]. - Society for Neuroscience

epetition of a WM task. Participants performed a series of runs that included either spatial WM
task repetition (1 run object, 5 spatial, 2 object, 1 spatial) or object WM task repetition (1 run
spatial, 5 object, 2 spatial, 1 object).
MS patients show similar decreases in neural activity as healthy adults within an inferior frontal
region during object task repetition. During spatial repetition in the superior frontal region,
however, MS patients show no change in activity while healthy adults again show decreased
activity. There were no regions in healthy adults that showed increasing activation with task
repetition, but the MS patients showed increasing activation in a posterior parietal region.
Behavioral results show no change in performance with task repetition for either patients or
controls during the 30 minute repetition period, suggesting that decreases in neural activity may
be interpreted as increases in neural efficiency.
These preliminary data suggest that at least in some cortical regions, MS results in a decreased
ability to alter activation efficiency with task repetition. Short-term neural plasticity may require
precisely timed interactions within orderly networks. The demyelination caused by MS may
disrupt these mechanisms. These results also suggest that previous results showing greater
activation (averaged across the entire scan session) for MS patients compared to healthy adults
may be due to a lack of decrease during repeated performance of a task rather than an overall
increase in activation.
Disclosures: C.A. Montojo, None; S.M. Courtney, None; S. Sayala, None.
Poster
288. Working Memory: Disorders, Genes and Connectivity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 288.5/RR12
Topic: F.01.f. Working memory
Title: Effects of childhood lead exposure on working memory: a functional MRI study
Authors: *J. S. SCHNEIDER 1 , J. LACKEY 2 , J. SHI 2 , S. LAI 2 ;
1 Dept Pathol, Anat. & Cell Biol, 2 Radiology, Thomas Jefferson Univ., Philadelphia, PA
Abstract: The neurotoxic effects of environmental lead exposure in children have been
recognized for over a century, but the mechanism of lead‟s toxicity on the developing central
nervous system remains poorly understood. While lead‟s effects on neurocognitive development
are obviously mediated by its neurotoxic effects on the developing brain, there has been no study
of how childhood lead exposure may alter brain function, manifested as brain activation levels
and/or patterns, during performance of tasks that involve working memory. Working memory or
the ability to hold and manipulate information on-line is an essential aspect of higher cognitive