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Abstract:
The roles of the multiple cortical areas involved in visual
working memory (WM) were investigated with fMRI using delayed match
to sample tasks for object identity of either houses or faces in 4
subjects. Others have observed greater parietal activation during
perception of houses than of faces (Haxby et al, 1999). It was
hypothesized that object WM for houses would recruit parietal and
dorsal frontal regions during delays, due to the analysis of
internal spatial relations possibly involved in remembering house
identity. Each trial consisted of: 1) serial presentation of three
sample stimuli, 2) 9s WM delay, 3) presentation of a test stimulus.
A direct comparison using multiple regression analysis contrasting
delay activity for house versus face WM revealed a double
dissociation within frontal cortex. Greater sustained activity was
evident for house WM delays bilaterally in the superior frontal
sulcus and in the right midfrontal gyrus, while greater sustained
activity was observed for face WM delays in the left inferior and
mid- frontal gyri. House WM delays also showed greater activation
in posterior parietal areas. These results suggest that spatially
specialized areas may be recruited during object WM to maintain
local spatial features within objects. Haxby JV et al., Neuron 22:
189-99; 1999. Courtney SM et al., Science 279: 1347-51; 1998.
Supported by: Johns Hopkins University
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