Estimation of the Neural Noise Within the Human Thalamus
It is demonstrated that the variation of the neural noise level along the descent of the electrode corresponds well to different subcortical structures, and is therefore reliable for identifying them precisely.
In and around the VL nucleus, there were some differences in the neural noise pattern between the medial and lateral groups. In the medial group (4 cases), upper borders of the thalamus were clearly delineated, but lower borders were not. Steep increases of the noise level were found about + 10 mm above IC-line probably corresponding to the entrance of VL nucleus and the upper half of the VL showed the highest level. On the other hand, in the lateral group (6 cases), intrathalamic noise patterns were not so characteristic as medial group and noise levels were lower. In three cases upper borders of the thalamus were not so distinct. Lower borders were, on the contrary, more clearly distinguished than the medial group.
Cases with simultaneous recordings with two electrodes in parallel with frontal section were reported. This method was proved to be useful in delineating the lateral edge of the thalamus, especially in the case with dilatation of the third ventricle.
In the Vim nucleus, high levels of the neural noise were demonstrated. Activity of kinesthetic neurons were mostly found, if any, among the higher noise levels.
KeywordsNoise Level Caudate Nucleus Medial Group Simultaneous Recording Frontal Section
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