In previous neuroimaging studies,
the human posterior parietal cortex has been identified as one intimately
involved in attentional processes. Dorsal aspects of the posterior parietal
cortex have been associated with “top-down” attention (i.e., focusing attention on external stimuli based on internal
goals of the subject) and ventral aspects of the posterior parietal cortex have
been associated with “bottom-up” attention (i.e.,
externally presented unexpected stimuli capturing one’s attention). Whilst
studying attention to externally applied stimuli is experimentally convenient,
focusing attention on internal events (e.g.,
conducting memory searches) is equally important. One might assume that the
posterior parietal cortex governs attention to memorized items similarly as in
the case of externally applied stimuli, however, it has not been systematically
tested whether the posterior parietal cortex is functionally segregated into
dorsal and ventral areas during cued vs.
non-cued recognition memory trials.
In their recent study, Burianová et al. (2012) tested, by presenting cued
vs. non-cued recognition memory trials during functional magnetic resonance
imaging, whether dorsal aspects of the posterior parietal cortex are more
involved in top-down memory searches and whether ventral aspects of the posterior
parietal cortex are more involved in non-cued bottom-up recognition memory. The
authors observed spatially dissociable networks of brain areas that overlapped
only in precuneus. During cued recognition memory trials (“top-down”), dorsal
posterior parietal cortex was functionally connected with areas comprising the
dorsal attention network as well as with memory-related brain areas; there was
further a significant correlation between cued memory recognition performance
and this network activity. In contrast, during uncued trials, ventral posterior
parietal cortex was functionally connected with the ventral attention system
and with relevant memory areas. These findings thus disclose a nice
double-dissociation of roles between dorsal and ventral posterior parietal
cortical areas in recognition memory that closely resembles the distinct roles
that these areas play in top-down vs. bottom-up attention.
Reference: Burianová H, Ciaramelli E, Grady CL, Moscovitch M. Top-down and bottom-up attention-to-memory:
mapping functional connectivity in two distinct networks that underlie cued and
uncued recognition memory. Neuroimage (2012) e-publication available prior to
publication. http://dx.doi.org/10.1016/j.neuroimage.2012.07.057
No comments:
Post a Comment
Any thoughts on the topic of this blog? You are most welcome to comment, for example, point to additional relevant information and literature on the topic. All comments are checked prior to publication on this site.