Visual and visuomotor processing of hands and tools as a case study of cross talk between the dorsal and ventral streams

ABSTRACT

A major principle of organization of the visual system is between a dorsal stream that processes visuomotor information and a ventral stream that supports object recognition. Most research has focused on dissociating processing across these two streams. Here we focus on how the two streams interact. We tested neurologically-intact and impaired participants in an object categorization task over two classes of objects that depend on processing within both streams—hands and tools. We measured how unconscious processing of images from one of these categories (e.g., tools) affects the recognition of images from the other category (i.e., hands). Our findings with neurologically-intact participants demonstrated that processing an image of a hand hampers the subsequent processing of an image of a tool, and vice versa. These results were not present in apraxic patients (N = 3). These findings suggest local and global inhibitory processes working in tandem to co-register information across the two streams.

KEYWORDS:

• Apraxia
• dorsal stream
• hands
• tools
• ventral stream

Acknowledgements

We thank speech therapist Gabriela Leal who provided us data regarding language evaluation of patients J.T. and A.B.

Disclosure statement

No potential conflict of interest was reported by the authors.

ORCID

Jorge Almeida http://orcid.org/0000-0002-6302-7564

Lénia Amaral http://orcid.org/0000-0002-0631-7944

Diana Aguiar de Sousa http://orcid.org/0000-0002-6702-7924

Isabel Pavão Martins http://orcid.org/0000-0002-9611-7400

Additional information

Funding

This research was supported by a Foundation for Science and Technology–Fundação para a Ciência e a Tecnologia of Portugal and Programa COMPETE grant [grant number PTDC/MHC-PCN/6805/2014] to J.A.; and a NSF [grant number 1349042] and NIH grants [grant number R21 NS076176 and R01 NSO89069] to BZM. Preparation of the manuscript was supported in part by a University of Rochester Center for Visual Science predoctoral training fellowship [NIH training grant number 5T32EY007125-24] to F.E.G. L.A. was supported by Fundação para a Ciência e a Tecnologia doctoral grant [grant number SFRH/BD/114811/2016].