Comparison of the orienting response during the intracarotid and posterior cerebral artery amobarbital tests: A case study

Skin conductance orienting response (OR) to a whistle was measured during selective cerebral deactivation associated with posterior cerebral (PCA) and intracarotid (ICA) amobarbital procedures in a seizure disorder patient. Complete suppression of the OR occurred following both right and left ICA procedures, whereas no reduction in the OR occurred following either PCA injection, Memory performance was independent of OR suppression, as adequate memory was evident in the intact right hemisphere and poor memory in the seizure focus hemisphere with both the ICA and PCA tests, Anosognosia occurred after the right ICA, but not the PCA procedures or the left ICA procedure. Selective unilateral deactivation of the hippocampus, mesial temporal and calcarine cortex, and lateral thalamus does not impair OR elicitation or awareness of deficit, whereas unilateral deactivation of ICA vascularized regions abolishes the OR, Conversely, anosognosia occurs following right ICA, but not with selective suppression of PCA vascularized cortical territories.