SVD single voxel analysisFrank Leone, Ivan Toni, Pieter Medendorp

Location = direction * amplitude?

vs

Singular value decomposition

Previous work: Location = X * Y (auditory domain)

Pena & Konishi, 2001

Previous work: Eye vs Hand relative tuning

Pesaran et al, 2006

Previous work: Eye vs Hand relative tuning

Pesaran et al, 2006

Closer inspection of fields

Roughly Gaussian

Correlation preferred amplitude and field width (?, in progress)

Extensions / applications

Test different representations:• X – Y• Multiplication vs addition

Test separability in general, of any two multivalue effects

More general: fit functions through your single voxel t-values, instead of making simple contrasts

T values or beta’s?

Conclusion

There is more than meets in the eye in single voxels

Can fit functions to your t-values

Can use SVD to test separability