A site directed fMRI approach for evaluating functional status in the anterolateral temporal lobes

Functional magnetic resonance imaging (fMRI) is increasingly being used for neurosurgical planning. One potential application relates to identifying eloquent cortex in regions immediately adjacent to epileptogenic foci in temporal lobe epilepsy (TLE). While medial temporal structures, such as the hippocampus and amygdala, are typically removed during surgery, it is often difficult to determine whether nearby cortical regions in the anterolateral temporal lobe should be spared. An essential first step is to identify a method of activating these regions in healthy individuals. The purpose of this study was to develop a site directed fMRI approach for evaluating functional status in the anterolateral temporal lobes. A picture-word matching task, with object category and level of abstraction factors, was used to characterize temporal lobe activation. Whole brain analysis at the group level confirmed the involvement of the temporal poles as well as adjacent superior, middle and inferior temporal gyri within a larger object recognition network. A region-of-interest analysis on the anterolateral temporal lobe demonstrated that activation varied across conditions and regions for individuals. Importantly, it was possible to detect activation in one or more conditions and/or regions for all individuals--demonstrating that it is possible to evaluate functional status. The findings provide the foundation for a novel fMRI approach in neurosurgical planning for TLE.