Delineation of motor and somatosensory thalamic subregions utilizing probabilistic diffusion tractography and electrophysiology.
OBJECTIVE
To employ and compare probabilistic diffusion tractography (PDT) for the explicit localization of connections from the thalamus to somatosensory cortex (S1) and primary motor cortex (M1) / supplementary motor area (SMA) with microelectrode electrophysiology in patients undergoing deep brain stimulation (DBS) surgery.


METHODS
These tractography-derived connections were used to categorize voxels in the thalamus as corresponding to sensory or motor physiology. A novel model (referred to in this work as the "mixture" model) to delineate PDT-based thalamic functional subregions by thresholding fiber intensities, ie, connectivity-defined regions (CDR), was devised. Regions created using this classification method were compared with the most commonly used model (referred to in this work as the "separation" or "winner takes all" model) for defining CDRs.


RESULTS
Electrophysiology data corresponded better for S1 CDRs created using the mixture model for both sensory and motor cells. Separation model CDRs showed poor correspondence against electrophysiology, with few sensory cells corresponding to the S1 separation model CDR.


CONCLUSIONS
Mixture model-based CDRs may offer a significant improvement in delineation of functional subregions of subcortical structures.
Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0265, USA. atchars@neurosurgery.ufl.edu
Atchar
A
Sudhyadhom
Keith
K
McGregor
Michael S
MS
Okun
Kelly D
KD
Foote
Jonathan
J
Trinastic
Bruce
B
Crosson
Frank J
FJ
Bova
D001931:Brain Mapping / Q000379:methods; D046690:Deep Brain Stimulation / Q000379:methods*; D056324:Diffusion Tensor Imaging / Q000379:methods*; D004566:Electrodes; D004594:Electrophysiology / Q000379:methods*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D009044:Motor Cortex / Q000473:pathology* / Q000502:physiology; D011336:Probability; D012372:ROC Curve; D015203:Reproducibility of Results; D013788:Thalamus / Q000473:pathology*