When action is not enough: tool-use reveals tactile-dependent access to Body Schema

Area of Science:

• Neuroscience
• Cognitive Psychology
• Motor Control

Background:

• Body Schema (BS) and Body Image (BI) are distinct representations for action and perception.
• Previous studies showed perceptual changes in BI without affecting BS.
• The current study investigates the opposite dissociation: BS update without BI change.

Purpose of the Study:

• To test if tool use updates the body schema (BS) without affecting body image (BI).
• To examine if tactile input is crucial for accessing the BS during motor tasks.
• To clarify the interplay between action, perception, and body representations.

Main Methods:

• Healthy participants localized anatomical landmarks on their arm before and after tool use.
• Both motor (BS) and perceptual (BI) localization tasks were used.
• Tasks were performed with verbal or tactile guidance to assess input modality effects.

Main Results:

• Both motor and perceptual tasks showed updates in forearm representation after tool use.
• These updates occurred only when the localization task was guided by tactile input.
• Motor output alone was insufficient for accessing the body schema.

Conclusions:

• The body schema is functionally updated by tool use, but requires tactile input.
• Tactile information is essential for integrating motor actions into the body schema.
• Findings refine action-perception models of body representation and highlight functional plasticity.