[Abstract Title]. - Society for Neuroscience

Program#/Poster#: 288.15/RR22
Topic: F.01.f. Working memory
Support: NIH grant R01 EB000473
Title: Influence of physiologic noise on fMRI measures of functional connectivity between task+
and task- brain areas
Authors: M. HAMPSON, *R. T. CONSTABLE;
Dept Diagnos. Radiol, Yale Univ., New Haven, CT
Abstract: Background: There has been great interest recently in a set of brain areas that
deactivates during many cognitive tasks. This set of brain areas has been referred to as the
default mode network, but we prefer the term task-negative brain areas. The functional
relationships between these task-negative brain areas and classic working memory areas,
otherwise known as task-positive brain areas, have been investigated in several studies. Negative
correlations, or anticorrelations have been reported between task+ and task- brain areas in resting
subjects and have been interpreted to reflect competition between cognitive and default mode
networks, although they could also reflect cooperation. The analytic methods used in typical
functional connectivity analyses include steps to normalize for the global signal (either by
dividing at each timepoint by the global mean, or regressing out the global timecourse). These
normalization steps help reduce the effects of physiologic noise, but can also distort correlational
patterns.
Methods: In this study, we collected simultaneous recordings of cardiac and respiratory cycles
during the imaging session. The influence of physiologic noise (including cardiac and respiratory
noise) on correlation patterns (particularly, on the anticorrelations between task- and task+ brain
areas) is examined by comparing functional connectivity patterns after removal of physiologic
noise sources (using RETROICORR) to those seen without physiologic noise removal. Results
are also compared to those obtained using global regression/normalization rather than
RETROICORR.
Conclusions: The direct recording and removal of cardiac and respiratory noise is recommended
in functional connectivity studies, particularly when examining the functional connectivity
patterns between task+ and task- brain areas.
Disclosures: M. Hampson, None; R.T. Constable , None.
Poster
288. Working Memory: Disorders, Genes and Connectivity
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm