Temporal cortex activation in humans viewing eye and mouth movements

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• The extrastriate visual cortex processes visual information beyond the primary visual cortex.
• Understanding the neural basis of social perception, including facial movements, is crucial.

Purpose of the Study:

• To investigate whether specific regions of the extrastriate visual cortex activate during the observation of eye and mouth movements.
• To differentiate the neural responses to facial movements from general motion stimuli.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity in eleven subjects.
• Subjects viewed moving eyes, moving mouths, and moving check patterns, all superimposed on a moving radial background to control for motion artifacts.
• A separate control task assessed activation from the moving radial background alone.

Main Results:

• Moving eyes and mouths bilaterally activated a region centered in the posterior superior temporal sulcus (STS).
• Moving check patterns did not significantly activate the STS.
• The STS activation was distinct from the activation by the moving radial background, which primarily engaged the posterior-temporal-occipital fossa and lateral occipital sulcus (area MT/V5).
• Area MT/V5 was also activated by moving eyes and other moving stimuli.

Conclusions:

• A superior temporal region, centered in the STS, is preferentially involved in perceiving gaze direction and mouth movements.
• This STS region may be functionally linked to other superior temporal areas involved in lip-reading and perception of body movements.