Using action understanding to understand the left inferior parietal cortex in the human brain

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Primate Comparative Neuroanatomy

Background:

• Humans possess intricate knowledge of object affordances and actions.
• Previous research identified neurons in macaque monkey inferior parietal cortex (area PFG) responding selectively to object-use contexts.
• The homologous human brain regions for this function remained largely uncharacterized.

Purpose of the Study:

• To investigate whether human knowledge of object actions relies on brain areas homologous to the macaque inferior parietal cortex (area PFG).
• To explore the neural basis of understanding object affordances and actions.
• To examine potential hemispheric asymmetries in these processes.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed to study brain activity.
• Participants viewed videos demonstrating object use in pantomime.
• Post-viewing, subjects identified the object corresponding to the pantomimed action.

Main Results:

• A significant cluster of activated voxels was identified in the human parietal cortex, specifically areas PFop and PFt.
• This activation cluster was notably larger in the left hemisphere compared to the right hemisphere.
• The findings suggest a potential neural correlate for understanding object-action knowledge.

Conclusions:

• The study supports the hypothesis that human object-action knowledge involves parietal areas homologous to those in macaque monkeys.
• Observed left-hemisphere dominance may relate to handedness and the human syndrome of apraxia.
• This mechanism could have played a role in early hominid communication for object naming or requesting.