VOLUME LXXVI | APR 2023

Patients with dorsal-stream lesions can perceive global shape

In an intriguing publication, Ayzenberg and Behrmann provide evidence that raises questions about the traditional understanding of how the brain processes global shape perception. They argue that global shape computation occurs in the dorsal visual stream before being transmitted to the ventral stream for object identification. However, a counterargument is posed by challenging the idea that patients with extensive dorsal-stream lesions would be unable to differentiate objects based on their global shape. This alternative perspective challenges the established paradigm and prompts further investigation into the role of the visual streams in perceiving shape. It is crucial to explore how neural networks and other neuroscientific methodologies can shed light on this topic. To delve deeper into this thought-provoking research, check out the full article!

Aiyana Tremblay

Aiyana is an Indigenous educator from Alberta, with a background in environmental science and community wellness programs. She volunteers as an author to explore how traditional knowledge intersects with modern neuroscience to unlock human resilience and potential.

In a provocative opinion piece, Ayzenberg and Behrmann (A+B) [1] present evidence, primarily from neuroimaging and deep neural networks (DNNs), for the idea that the global shape of objects is computed in the dorsal visual stream and is then transferred to the ventral stream where it contributes to object identification. In our commentary on their article, we challenged this proposal, arguing that, if global shape were computed in the dorsal stream, then one would expect patients with large bilateral lesions of the dorsal stream to be unable to discriminate between objects on the basis of their global shape [2].
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