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Updated: May 19, 2026
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Investigating Object Representations in the Macaque Dorsal Visual Stream Using Single-unit Recordings
Published on: August 1, 2018
Selectivity for three-dimensional shape and grasping-related activity in the macaque ventral premotor cortex
Tom Theys1, Pierpaolo Pani, Johannes van Loon
1Laboratorium voor Neuro- en Psychofysiologie and Afdeling Experimentele Neurochirurgie en Neuroanatomie, Katholieke Universiteit Leuven, B-3000 Leuven, Belgium.
Summary
Area F5a in the macaque ventral premotor cortex exhibits unique neuronal selectivity for three-dimensional (3D) shapes. These neurons are visually dominant, responding to object shape but not during grasping in the dark.
Area of Science:
- Neuroscience
- Primate motor cortex research
- Visual-motor integration
Background:
- Ventral premotor cortex (area F5) has distinct sectors, including F5a.
- Functional characterization of F5a at the single-cell level is lacking.
- Previous monkey fMRI data suggested F5a's role in 3D shape processing.
Purpose of the Study:
- To investigate neuronal selectivity for 3D shape in F5a.
- To examine the relationship between disparity selectivity and grasping activity in F5a.
- To functionally distinguish F5a from neighboring regions (F5p, 45B).
Main Methods:
- Single-cell electrophysiological recordings in macaque F5a.
- Neuronal responses analyzed for selectivity to 3D curved surfaces (disparity-defined).
- Recordings conducted during visually guided grasping tasks (light and dark conditions).
Main Results:
- The majority of F5a neurons showed selectivity for 3D curved surfaces, with higher-order disparity selectivity.
- F5a neurons demonstrated robust 3D shape selectivity independent of motor response.
- Neurons encoding 3D shape responded during grasping in light but not in darkness, indicating visual dominance.
Conclusions:
- F5a is functionally distinct from F5p and 45B due to its 3D shape selectivity and visual dominance.
- Findings support F5a's role in processing object shape for visually guided actions.
- Results align with anatomical connectivity studies differentiating F5a subregions.
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