Abstracts

Rationale: Using explicit information, decision making leads to bilateral fMRI activations within lateral prefrontal, fronto-mesial, and parietal cortex in normal control subjects (Labudda et al., 2008). It is, however, unclear whether epilepsy surgery within these areas leads to postsurgical changes of decision making behavior and/or changes of associated fMRI activations. Methods: In a 51 y old patient with medically intractable epilepsy and a right fronto-mesial focal cortical dysplasia, we conducted pre- and postsurgical fMRIs using a 1.5 T MRI scanner. We used a paradigm designed to identify the cortical areas implicated in decision making. During this paradigm explicit information on probabilities and potential consequences of the respective decisions were displayed. This task had already been used in 12 normal control subjects (Labudda et al., 2008). Results: The patient’s task performances during the fMRI experiments did not differ between pre- and postsurgical measurements. At both points in time, the patient came to advantageous decisions (preoperatively 29, postoperatively 32 advantageous of a total of 36 decisions). Pre- and postoperative fMRI activations differed with a postsurgical increase of signal in the left sided dorsolateral prefrontal, orbito-frontal, and parietal cortices (Z>=3.9, p>=0.04). Conclusions: Using explicit information, the patient was able to come to advantageous decisions despite frontal lobe epilepsy surgery. Comparing pre- and postsurgical fMRI activations, there was a differential pattern of activation in this single case. The postsurgical increase of fMRI activity in the non-operated frontal lobe and in the ipsilateral parietal lobe included fronto-orbital areas which were not activated in a group of normal control subjects. Whether these findings can be replicated and whether they indicate either cognitive and/or neuronal reorganisation, has to be shown in a larger sample of patients with epilepsy. Labudda et al., Exp Brain Res 2008 ;187 :641-650.