title: Depth electrode recorded cerebral responses with deep brain stimulation of the anterior thalamus for epilepsy.
abstract: OBJECTIVE
  We investigated the relation between anterior thalamic stimulation and the morphology of the evoked cerebral responses (CRs) using intracerebral depth electrodes in patients with intractable epilepsy undergoing deep brain stimulation (DBS) of the thalamus.
  
  
  METHODS
  Monopolar cathodic and bipolar stimuli were delivered at a rate of 2 or 1 Hz to the anterior nucleus (AN) and the dorsomedian nucleus (DM) of two patients using the programmable stimulation device (Medtronic ITREL II) or a GRASS stimulation device (S12). CRs were recorded from depth or DBS electrodes, situated bilaterally in mesial temporal (hippocampus, both patients), lateral temporal (one patient), orbitofrontal (Brodmann area 11, one patient) and anterior thalamic sites (one patient).
  
  
  RESULTS
  The distribution and morphology of the CRs depended primarily on the site of stimulation within the anterior thalamic region. Overall, monopolar cathodic and bipolar stimulation of the AN elicited CRs mainly in ipsilateral mesial temporal cortical areas, whereas stimulation of the DM evoked high-amplitude CRs predominantly in ipsilateral orbitofrontal areas. The amplitude of the CR was positively related to the strength of the stimulus and generally higher with monopolar than with bipolar stimulation. The differences between CRs elicited during wakefulness or slow wave sleep were minimal.
  
  
  CONCLUSIONS
  The distribution of the CRs corresponded with the intracerebral pathways of the involved structures and the findings are in good accordance with those of our previous study investigating the sources of CRs using statistical non-parametric mapping of low resolution electromagnetic tomography (LORETA) values.
  
  
  CONCLUSIONS
  Our findings indicate a certain degree of point-to-point specificity within the thalamocortical circuitry, which may make optimal localization of DBS electrodes important in patients with epilepsy.
authors.affiliation: Krembil Neuroscience Centre, Toronto Western Hospital, University of Toronto, 399 Bathurst Street, Toronto, Ont., Canada M5T 2S8. dzumsteg@uhnres.utoronto.ca
authors.forename: Dominik
authors.initials: D
authors.lastname: Zumsteg
authors.forename: Andres M
authors.initials: AM
authors.lastname: Lozano
authors.forename: Richard A
authors.initials: RA
authors.lastname: Wennberg
mesh_terms: D000328:Adult; D020643:Anterior Thalamic Nuclei / Q000503:physiopathology / Q000528:radiation effects*; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000503:physiopathology*; D046690:Deep Brain Stimulation / Q000379:methods*; D004566:Electrodes; D004569:Electroencephalography; D004827:Epilepsy / Q000473:pathology / Q000628:therapy*; D005260:Female; D007839:Functional Laterality / Q000528:radiation effects; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male