Preserved Responsiveness of Secondary Somatosensory Cortex in Patients with Thalamic Stroke

Birol Taskin, Gerhard Jan Jungehulsing, Jan Ruben, Peter Brunecker, Thomas Krause, Felix Blankenburg, Arno Villringer
2005 Cerebral Cortex  
Cortical representations may change when somatosensory input is altered. Here, we investigated the functional consequences of partial "central" deafferentation of the somatosensory cortex due to a lesion of the ventroposterior lateral nucleus (VPL) in patients at a chronic stage after solitary infarction of the thalamus. Event-related functional magnetic resonance imaging during electrical index finger stimulation of the affected and nonaffected side was performed in 6 patients exhibiting
more » ... lesional sensory deficits (mainly hypesthesia). Involvement of the VPL and additional nuclei was determined by high-resolution magnetic resonance imaging (MRI) and subsequent MRI-to-atlas coregistration. For the group, statistical parametric maps showed a reduced activation of contralateral primary somatosensory cortex (SI) in response to stimulation of the affected side. However, no significant difference in the activation of contralateral secondary somatosensory cortex (SII) compared with stimulation of the nonaffected side was detected. Correspondingly, the ratio of SII-to-SI activation for the ipsilesional hemisphere was markedly elevated as compared with the contralesional hemisphere. For preserved responsiveness of SII in thalamic stroke comparable with that of the contralesional hemisphere, possible explanations are a direct thalamocortical input to SII mediating parallel information processing, nonlinear response behavior of SII in serial processing, or reorganizational processes that evolved over time.
doi:10.1093/cercor/bhj080 pmid:16357339 fatcat:wkyvxijvwrfp7hgmhh3htvndoi