Direct functional connectivity between the thalamus (Vim) and the contralateral motor cortex: Just a single case observation or a common pathway in the human brain?

In this case report we present in vivo evidence of direct bilateral cortico-thalamic connectivity on a patient with fragile-x tremor ataxia syndrome who underwent deep brain stimulation (DBS) surgery for bilateral severe rest and kinetic tremor. We use very short latency cortical evoked responses (CER) as evidence of a direct anatomical pathway between the thalamus and the ipsilateral and contralateral cortex. CERs with various latencies have been previously reported from patients undergoing DBS for intractable tremor and from experimental models in primates [1], [2], [3], [4].