Visual sensitivity at the service of action control in posterior parietal cortex

TL;DR

The study explores how the posterior parietal cortex uses visual information to control actions, showing that visual representations adapt based on the context of the action.

Contribution

The paper reveals that the medial PPC (area V6A) dynamically encodes object shape for action control, emphasizing visual perception of actions over object recognition.

Findings

Neural activity in V6A is influenced by visual information during reaching and grasping actions.

Three-dimensional object shape is encoded dynamically in V6A according to the monkey's behavioral context.

Mirror neuron discharges in V6A show plasticity in visual representation of graspable objects based on action context.

Abstract

The posterior parietal cortex (PPC) serves as a crucial hub for the integration of sensory with motor cues related to voluntary actions. Visual input is used in different ways along the dorsomedial and the dorsolateral visual pathways. Here we focus on the dorsomedial pathway and recognize a visual representation at the service of action control. Employing different experimental paradigms applied to behaving monkeys while single neural activity is recorded from the medial PPC (area V6A), we show how plastic visual representation can be, matching the different contexts in which the same object is proposed. We also present data on the exchange between vision and arm actions and highlight how this rich interplay can be used to weight different sensory inputs in order to monitor and correct arm actions online. Indeed, neural activity during reaching or reach-to-grasp actions can be excited or inhibited by visual information, suggesting that the visual perception of action, rather than object recognition, is the most effective factor for area V6A. Also, three-dimensional object shape is encoded dynamically by the neural population, according to the behavioral context of the monkey. Along this line, mirror neuron discharges in V6A indicate the plasticity of visual representation of the graspable objects, that changes according to the context and peaks when the object is the target of one’s own action. In other words, object encoding in V6A is a visual encoding for action.

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