Structural Connectivity for Visuospatial Attention: Significance of Ventral Pathways

Abstract

In the present study, we identified the most probable trajectories of point-to-point segregated connections between functional attentional centers using a combination of functional magnetic resonance imaging and a novel diffusion tensor imaging-based algorithm for pathway extraction. Cortical regions activated by a visuospatial attention task were subsequently used as seeds for probabilistic fiber tracking in 26 healthy subjects. Combining probability maps of frontal and temporoparietal regions yielded a network that consisted of dorsal and ventral connections. The dorsal connections linked temporoparietal cortex with the frontal eye field and area 44 of the inferior frontal gyrus (IFG). Traveling along superior longitudinal and arcuate fascicles, these fibers are well described in relation to spatial attention. However, the ventral connections, which traveled in the white matter between insula (INS) cortex and putamen parallel to the sylvian fissure, were not previously described for visuospatial attention. Linking temporoparietal cortex with anterior INS and area 45 of IFG, these connections may provide an anatomical substrate for crossmodal cortical integration needed for stimulus perception and response in relation to current intention. The newly anatomically described integral network for visuospatial attention might improve the understanding of spatial attention deficits after white matter lesions.

Ventral and dorsal fiber systems for imagined and executed movement

“…Parietal fiber contributions to EmC were found to terminate primarily in insulate cortex (Pandya and Kuypers 1969;Jones and Powell 1970;Petrides and Pandya 1984;Schmahmann and Pandya 2006;Roberts et al 2007). While these data support the notion of a ventral pattern of connectivity of the VLPFC and IFGpt via the EmC, it cannot substantiate a direct prefronto-parietal connection as suggested by our and others DTI data (Catani et al 2002;Wakana et al 2004;Makris and Pandya 2009;Umarova et al 2010). We cannot rule out that methodological differences and shortcomings contribute to the partially divergent results of human DTI and animal tracer studies.…”

“…These prefrontal areas are known to connect toward posterior areas primarily along ventral fibers via the extreme capsule and not through dorsal AF/SLF pathways Kuypers 1969, Petrides andPandya 1984;Schmahmann andPandya 2006, Anwander et al 2007;Frey et al 2008). The dichotomization into ventral and dorsal processing streams in the visual system (Ungerleider and Mishkin 1982;Milner and Goodale 1996) has recently been extended to the domains of language and spatial attention Umarova et al 2010). Consequently, a functionally and anatomically segregated domain general architecture of dorsal and ventral white matter tracks in the brain, connecting post-and prerolandic cortices, has been proposed (Weiller et al 2011).…”

Distinct Frontoparietal Networks Set the Stage for Later Perceptual Identification Priming and Episodic Recognition Memory

“…Our findings suggest that dorsolateral prefrontal cortex may also support much lower-level encoding processes that set the stage for later perceptual priming. Attentional binding is one such prerequisite for priming (Hayman and Jacoby, 1989;Schacter et al, 1991;Richardson-Klavehn and Gardiner, 1998), and could be achieved via the strong connections of this area with the ventral posterior parietal lobe (Petrides and Pandya, 1999;Petrides, 2005;Umarova et al, 2010). Support for a binding function of the superior PFC comes from an fMRI investigation showing that connectivity between this same area and modality-specific late visual areas predicts successful associative recognition (Summerfield et al, 2006).…”

Functional Asymmetries Revealed in Visually Guided Saccades: An fMRI Study

“…Recent studies have demonstrated that the perisylvian parietal, superior temporal, and lateral frontal cortices are tightly connected in the human right hemisphere (Gharabaghi et al 2009;Umarova et al 2009). Additionally, the middle component of the superior longitudinal fasciculus connects between the lateral FEF and the aIPS in a nonhuman primate (see DISCUSSION in Lee et al 2006).…”