Friday, December 28, 2007

Motion perception and production - similar neural coding

Another example of how our brain's representations of motion are tuned to biological actions. Here is the abstract of the open access article from Dayan et al., which contains some very elegant imaging figures:
Behavioral and modeling studies have established that curved and drawing human hand movements obey the 2/3 power law, which dictates a strong coupling between movement curvature and velocity. Human motion perception seems to reflect this constraint. The functional MRI study reported here demonstrates that the brain's response to this law of motion is much stronger and more widespread than to other types of motion. Compliance with this law is reflected in the activation of a large network of brain areas subserving motor production, visual motion processing, and action observation functions. Hence, these results strongly support the notion of similar neural coding for motion perception and production. These findings suggest that cortical motion representations are optimally tuned to the kinematic and geometrical invariants characterizing biological actions.

[Note: The 2/3 power law links path curvature C and angular velocity A along the movement by a power law with an exponent of 2/3. K is the velocity gain factor, which is piecewise constant during entire movement segments:

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