Abstract
The role of the ventral anterior temporal lobe (ATL) in language processing remains unclear. In particular, electrical disruption of much of the ventral temporal cortex has been shown to effect naming. Here, we present intracranial electroencephalography (iEEG), direct cortical stimulation, 7T fMRI, and neuropsychology results that describe a new word sensitive region at the anterior tip of the fusiform gyrus, which we dub the anterior fusiform naming area. In 4 epilepsy patients undergoing iEEG, electrodes in the left anterior fusiform exhibited word sensitivity over five other categories of visual stimuli. Direct cortical stimulation was administered to one patient, disrupting word reading when applied to the word sensitive electrode. The word sensitivity demonstrated in these studies is consistent with 7T fMRI findings of sensitivity to words versus objects in the anterior fusiform. Additionally, neuropsychological testing performed with 2 of 2 patients following left ATL resection that included this region revealed surface dyslexia, which is characterized by "over-regularization" of exception words (e.g., "sew" read as "sue"). In contrast, 1 of 1 patient with an equivalent right hemisphere resection tested with normal reading ability. Anterior temporal lobectomy is standard surgical treatment for intractable epilepsy, and to our knowledge, these are the first reported cases of surface dyslexia following the procedure. Given that surface dyslexia is a robust early symptom in the progression of neurodegenerative diseases of the ATL, these results emphasize the role of this region in reading and language processing and strongly suggest the presence of a word sensitive patch at the anterior tip of the fusiform. We hypothesize that this patch is critical for reading exception words that must be processed as unique entities, paralleling other findings that describe a role for ATL regions in processing other types of unique entities, such as famous faces and landmarks.
Meeting abstract presented at VSS 2018