Disentangling hand and tool processing: Distal effects of neuromodulation

Area of Science:

• Neuroscience
• Cognitive Science
• Neuroimaging

Background:

• The posterior middle temporal gyrus (pMTG) processes multiple object categories like hands and tools.
• Functional connectivity suggests local processing in pMTG influences and is influenced by distant brain areas in a category-specific manner.

Purpose of the Study:

• To investigate if transcranial direct current stimulation (tDCS) paired with hand or tool training modulates neural processing in the pMTG.
• To determine if this modulation affects local and distal neural processing for trained versus untrained categories.

Main Methods:

• Participants underwent combined tDCS and category-specific training (hands or tools).
• Subsequent functional magnetic resonance imaging (fMRI) with multivoxel pattern analysis was used to assess neural processing of tools, hands, and animals.
• tDCS was applied to the pMTG, a region responsive to both hands and tools.

Main Results:

• tDCS with tool training improved classification accuracy between tools and animals.
• Surprisingly, tDCS with tool training also improved classification accuracy between hands and animals.
• Neither training task combined with tDCS improved classification for the untrained category.

Conclusions:

• Category-specific training combined with tDCS can selectively engage overlapping but functionally distinct neural networks.
• This strategy offers a novel approach for modulating neural processing and can be broadly applied to other cognitive domains.
• Observed effects on local processing are likely due to connectivity constraints within domain-specific networks.