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Updated: Jun 20, 2026

Corticospinal Excitability Modulation During Action Observation
Published on: January 1, 2014
Distinct olfactory cross-modal effects on the human motor system
Simone Rossi1, Alberto De Capua, Patrizio Pasqualetti
1Dipartimento di Neuroscienze, Sezione Neurologia, University of Siena, Siena, Italy. Rossisimo@unisi.it
Food odors can enhance motor system activity when observing grasping actions, but only when the smell and the observed food match. This cross-modal effect is specific to certain odors and muscles, suggesting potential applications in diagnostics and rehabilitation.
Area of Science:
- Neuroscience
- Sensory Integration
- Motor Control
Background:
- Action observation and sounds activate the human motor system cross-modally.
- Olfaction, a primal sense, may influence human behavior and motor activities.
Purpose of the Study:
- To investigate if food odors facilitate the human motor system during action observation.
- To determine the specificity of olfactory-induced motor facilitation.
Main Methods:
- Used transcranial magnetic stimulation (TMS) on 24 healthy individuals.
- Employed a repeated-measure block design across three experiments.
- Tested responses to alimentary and noxious odorants during object grasping observation.
Main Results:
- Sniffing food odors immediately increased motor potentials in hand muscles.
- This facilitation was odorant-specific and absent for noxious odors.
- The effect was additive to action observation, congruent with the observed food, and muscle-specific.
Conclusions:
- Olfactory cross-modal effects on the human corticospinal system are physiologically demonstrable.
- These effects are specific to odor, muscle, and action, depending on context.
- Findings suggest potential diagnostic and rehabilitative applications for olfactory-motor interactions.
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06:13Combining a Breath-Synchronized Olfactometer with Brain Simulation to Study the Impact of Odors on Corticospinal Excitability and Effective Connectivity
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