Representing tools as hand movements: Early and somatotopic visuomotor transformations

The term affordance defines a property of objects, which relates to the possible interactions that an agent can carry out on that object. In monkeys, canonical neurons encode both the visual and the motor properties of objects with high specificity. However, it is not clear if in humans exists a sim...

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Bibliographic Details
Published in:Neuropsychologia 2014-08, Vol.61, p.335-344
Main Authors: Bartoli, Eleonora, Maffongelli, Laura, Jacono, Marco, D’Ausilio, Alessandro
Format: Article
Language:English
Subjects:
Activity levels. Psychomotricity
Adaptation-stimulation
Adult
Affordance
Biological and medical sciences
Canonical neurons
Female
Fundamental and applied biological sciences. Psychology
Hand - physiology
Humans
Male
Motor Cortex - physiology
Muscle, Skeletal - physiology
Psychology. Psychoanalysis. Psychiatry
Psychology. Psychophysiology
Psychomotor activities
Psychomotor Performance - physiology
Reaction Time
TMS
Transcranial Magnetic Stimulation
Visual Perception - physiology
Visuomotor transformations
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Summary:The term affordance defines a property of objects, which relates to the possible interactions that an agent can carry out on that object. In monkeys, canonical neurons encode both the visual and the motor properties of objects with high specificity. However, it is not clear if in humans exists a similarly fine-grained description of these visuomotor transformations. In particular, it has not yet been proven that the processing of visual features related to specific affordances induces both specific and early visuomotor transformations, given that complete specificity has been reported to emerge quite late (300–450ms). In this study, we applied an adaptation-stimulation paradigm to investigate early cortico-spinal facilitation and hand movements׳ synergies evoked by the observation of tools. We adapted, through passive observation of finger movements, neuronal populations coding either for precision or power grip actions. We then presented the picture of one tool affording one of the two grasps types and applied single-pulse Transcranial Magnetic Stimulation (TMS) to the hand primary motor cortex, 150ms after image onset. Cortico-spinal excitability of the Abductor Digiti Minimi and Abductor Pollicis Brevis showed a detailed pattern of modulations, matching tools׳ affordances. Similarly, TMS-induced hand movements showed a pattern of grip-specific whole hand synergies. These results offer a direct proof of the emergence of an early visuomotor transformation when tools are observed, that maintains the same amount of synergistic motor details as the actions we can perform on them. •Early and somatotopic visuo-motor transformations occur during vision of tools.•Visuo-motor transformations elicit specific motor synergies.•Specific synergies are shown by corticospinal excitability and TMS-induced movements.•Action observation prior to tool presentation modulates the evoked motor synergy.•A cross-talk between mirror and canonical neuron systems is suggested.
ISSN:0028-3932
1873-3514
DOI:10.1016/j.neuropsychologia.2014.06.025