Tactile Discrimination Task Not Disturbed by Thalamic Stimulation

Abstract

The major pathway of human somatosensation passes through the ventrocaudal nucleus (Vc) of the thalamus. We tested the effect of direct electrical stimulation of the Vc on tactile discrimination in 5 Parkinson patients undergoing stereotactic thalamotomy. Raised gratings with lines 3, 4, or 6 mm apart were used. Patients had to actively touch test patterns placed in the hand contralateral to the thalamus under operation and compare it with a reference 3-mm grating held continuously in their other hand. Their performance was best for 6-mm, followed by 3-mm and then by 4-mm patterns regardless of electrical stimulation. Under Vc stimulation, patients recognized the 4-mm gratings slightly better. This can be explained either by the nature of thalamocortical interaction, which makes it resistant to external noise, or by the involvement of other pathways that circumvent the effect of thalamic stimulation.

Ill-posed medicine—an introduction to image registration

“…An alternative, though less commonly used approach is the so-called Lagrangian map, where basically T Lagrange [y](x) := T (y −1 (x)) (in a proper formulation, the inverse transformation is not required). images from [43], see http://cns.bu.edu/∼rash/paper.htm; (c) image with principal axis deduced from second-order moments.…”

“…Figure 7. (a) MR scan of a human head with manually set landmarks; (b) stereotactic frame;images from[43], see http://cns.bu.edu/∼rash/paper.htm; (c) image with principal axis deduced from second-order moments.…”