Separate representations of static and dynamic touch in human somatosensory thalamus.

Abstract

Pure sensory thalamic strokes are often attributed to the ventral posterior lateral nucleus (VPL) and can lead to selective loss of a sensory modality, such as proprioception, while preserving other sensory modalities.1 In humans, touch is mediated by different classes of low-threshold mechanoreceptors. Short changes in skin indentation, such as short taps or dynamic von Frey hair testing (D-vFHT), activate rapidly adapting mechanoreceptors (RA-M), whereas constant skin indentation, as during static von Frey hair testing (S-vFHT), is mainly mediated by slowly adapting mechanoreceptors (SA-M).2 However, in primate VPL, the spatial organization of neurons coding for RA-M and SA-M has remained controversial.3-5 Here we describe a patient with impaired perception of static but not dynamic tactile stimuli due to a small VPL infarct. Our findings provide evidence for spatially segregated representations of RA-M and SA-M within the human VPL. A 30-year-old patient was admitted because of a sudden onset of numbness on the left side of the body and a short-lasting visual disturbance. His medical history was unremarkable. On examination the patient was alert and orientated. On sensory testing, a dissociation in the perception of static and dynamictouch …