A parietal region processing numerosity of observed actions: An FMRI study

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Observing actions involves processing both action identity and frequency.
• The posterior parietal cortex is implicated in action observation, particularly manipulative actions.
• Understanding how the brain processes observed action numerosity is crucial.

Purpose of the Study:

• To identify the specific parietal brain regions involved in processing the numerosity of observed manipulative actions (OMAs).
• To differentiate the roles of brain areas in processing action identity versus action numerosity.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to scan 21 healthy volunteers.
• Participants performed discrimination tasks involving observed manipulative actions (OMAs) and colors.
• Stimuli included videos of actions performed on colored balls with varying numerosities.

Main Results:

• Significant differences between action and ball discrimination tasks were found in the occipito-temporal cortex and left parietal regions.
• The putative human anterior intraparietal sulcus (phAIP) and the post-central sulcus (NPC3) showed differential activation.
• Region of interest analysis indicated NPC3 specifically favored the numerosity of observed actions, while phAIP processed action identity.

Conclusions:

• The findings suggest a functional specialization within the parietal cortex for processing observed actions.
• phAIP is likely involved in identifying the type of observed manipulative action.
• NPC3 appears to be a key area for processing the number of observed actions.