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Corticospinal Excitability Modulation During Action Observation
Published on: December 31, 2013
Context and hand posture modulate the neural dynamics of tool-object perception.
Nikhilesh Natraj1, Victoria Poole, J C Mizelle
1Cognitive Motor Control Laboratory, School of Applied Physiology, Georgia Tech, Atlanta, GA 30332-0356, USA.
Neuropsychologia
|December 25, 2012
Summary
Tool perception involves complex brain activity, with non-functional grasps delaying judgments by engaging extended neural networks. This study reveals how hand posture and context influence visual processing of tools and objects.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Human Motor Control
Background:
- Visual perception of tools is linked to motor strategies, activating brain regions like the posterior parietal cortex.
- Observing tool use involves the inferior frontal cortex, but real-world use is context and grasp-specific.
- Prior research showed context and grasp posture modulate reaction times in tool-object evaluation.
Purpose of the Study:
- To investigate the neural mechanisms underlying behavioral interference observed with non-functional tool grasps.
- To test if non-functional (Manipulative) grasps in a functional (Correct) tool-object context increase parietofrontal activity.
- To determine if this neural effect is specific to contexts with high action affordances.
Main Methods:
- Recorded 64-channel electroencephalography (EEG) from 16 subjects viewing tool-object images.
- Images depicted three contexts (Correct, Incorrect, Spatial) modified by four hand interactions (No Hand, Static, Functional, Manipulative).
- EEG data analyzed in time-voltage and time-frequency domains to assess neural responses.
Main Results:
- All hand postures (Static, Functional, Manipulative) induced early parietofrontal activation (100-400ms) compared to No Hand.
- In the Correct context, the Manipulative posture uniquely extended neural responses (400-600ms) over right parietofrontal areas, with theta band power increase.
- In the Spatial context, the Manipulative posture also extended neural responses (400-600ms) over bilateral parietofrontal and left motor areas, with beta band power decrease.
Conclusions:
- Neural processing of tool-object perception is sensitive to hand posture and context.
- A non-functional Manipulative grasp in a functional context engages a late right parietofrontal network, suggesting evaluation of action affordances.
- Ambiguous contexts with Manipulative grasps increase bilateral parietofrontal activation, indicating networks for evaluating associations when motoric affordances are unclear.
