TY - JOUR
T1 - Effects of Verbal Working Memory Load on Corticocortical Connectivity Modeled by path analysis of functional magnetic resonance imaging data.
AU - Honey, G D
AU - Fu, C Y
AU - Kim, J
AU - Brammer, M J
AU - Croudage, T J
AU - Suckling, J
AU - Pich, E M
AU - Williams, S C R
AU - Bullmore, E T
PY - 2002
Y1 - 2002
N2 - We investigated the hypothesis that there are load-related changes in the integrated function of frontoparietal working memory networks. Functional magnetic resonance imaging time-series data from 10 healthy volunteers performing a graded n-back verbal working memory task were modeled using path analysis. Seven generically activated regions were included in the model: left/right middle frontal gyri (L/R MFG), left/right inferior frontal gyri (L/R IFG), left/right posterior parietal cortex (L/R PPC), and supplementary motor area (SMA). The model provided a good fit to the 1-back (chi(2) = 7.04, df = 8, P = 0.53) and 2-back conditions (chi(2) = 9.35, df = 8, P = 0.31) but not for the 3-back condition (chi(2) = 20.60, df = 8, P = 0.008). Model parameter estimates were compared overall among conditions: there was a significant difference overall between 1-back and 2-back conditions (chi(diff)(2) = 74.77, df = 20, P <0.001) and also between 2-back and 3-back conditions (χ(2)(diff) diff = 96.28, df = 20, P <0.001). Path coefficients between LIFG and LPPC were significantly different from zero in both 1-back and 2-back conditions; in the 2-back condition, additional paths from LIFG to LPPC via SMA and to RMFG from LMFG and LPPC were also nonzero. This study demonstrated a significant change in functional integration of a neurocognitive network for working memory as a correlate of increased load. Enhanced inferior frontoparietal and prefrontoprefrontal connectivity was observed as a correlate of increasing memory load, which may reflect greater demand for maintenance and executive processes, respectively. (C) 2002 Elsevier Science (USA).
AB - We investigated the hypothesis that there are load-related changes in the integrated function of frontoparietal working memory networks. Functional magnetic resonance imaging time-series data from 10 healthy volunteers performing a graded n-back verbal working memory task were modeled using path analysis. Seven generically activated regions were included in the model: left/right middle frontal gyri (L/R MFG), left/right inferior frontal gyri (L/R IFG), left/right posterior parietal cortex (L/R PPC), and supplementary motor area (SMA). The model provided a good fit to the 1-back (chi(2) = 7.04, df = 8, P = 0.53) and 2-back conditions (chi(2) = 9.35, df = 8, P = 0.31) but not for the 3-back condition (chi(2) = 20.60, df = 8, P = 0.008). Model parameter estimates were compared overall among conditions: there was a significant difference overall between 1-back and 2-back conditions (chi(diff)(2) = 74.77, df = 20, P <0.001) and also between 2-back and 3-back conditions (χ(2)(diff) diff = 96.28, df = 20, P <0.001). Path coefficients between LIFG and LPPC were significantly different from zero in both 1-back and 2-back conditions; in the 2-back condition, additional paths from LIFG to LPPC via SMA and to RMFG from LMFG and LPPC were also nonzero. This study demonstrated a significant change in functional integration of a neurocognitive network for working memory as a correlate of increased load. Enhanced inferior frontoparietal and prefrontoprefrontal connectivity was observed as a correlate of increasing memory load, which may reflect greater demand for maintenance and executive processes, respectively. (C) 2002 Elsevier Science (USA).
U2 - 10.1016/S1053-8119(02)91193-6
DO - 10.1016/S1053-8119(02)91193-6
M3 - Article
SN - 1095-9572
VL - 17
SP - 573
EP - 582
JO - NeuroImage
JF - NeuroImage
IS - 2
ER -