Abstract
Don Macleod has been our colleague and friend since we were all graduate students in Cambridge. Although Don’s outstanding research trajectory has included rather different areas from ours, they have touched in places (e.g. motion processing) – and the Macleods’ generous hospitality has augmented many of our research collaborations in San Diego.
One San Diego link, with Ursula Bellugi, introduced us to Williams syndrome (WS), an intriguing genetic disorder, with severe visuospatial deficits but relatively spared language and object recognition. We found relatively poor motion coherence sensitivity compared to static form, suggesting a specific dorsal stream deficit in WS. However, our work and others’ found that many other genetic and acquired neurodevelopmental disorders shared this deficit, leading us to propose ‘dorsal stream vulnerability’ – a cluster of motion, visuomotor, and attention deficits.
In a recent San Diego collaboration, global motion and form sensitivity were measured in a large group of children in Terry Jernigan’s PLING study. Individual differences in global motion sensitivity were associated with an enlarged parietal lobe, particularly around the intraparietal sulcus, and variations in the superior longitudinal fasciculus linking parietal and frontal areas. This parietal network has been implicated in numerical cognition. Children showing higher motion sensitivity also scored higher on early math tests (but not word reading, and no association of math with form coherence).
We will discuss these results in relation to the broader phenomenon of ‘dorsal stream vulnerability’, decision processes for global motion, links to the dorsal attention system, and possibly to Duncan’s ‘multiple-demand network’.