Verbs and nouns in awake neurosurgery: needs and answers

Awake surgery is a surgical procedure applied to people with brain tumors. Patients are kept awake during surgery to perform language tasks during electrical stimulation of cortico-subcortical brain structures. When the application of electrical pulses to the brain repeatedly triggers errors, this is taken as an indication that the area is critically involved in the language skills probed by the task, and therefore should not be removed, as this would result in postoperative language deficits. In this thesis, we focused on the role of production tasks using finite verbs and the evaluation of their ability to assess language processing in comparison with the current gold standard (i.e., object naming). As a preliminary step in the development of novel, controlled object and verb production tasks, we critically reviewed the literature. We discussed published studies that proposed intraoperative tasks requiring the production of verbs in isolation and in sentences, and we graphically represented the stimulation sites and error types that were reported in each study. Subsequently, we discussed the advantages and disadvantages of each from a cognitive neuroscience and neurolinguistic perspective. With this information in mind, we constructed and validated two naming tasks for native speakers of Italian undergoing awake surgery – an object naming task and a finite verb production task. We administered the finite verb production task and other picture naming tasks to subjects with post-stroke aphasia, and established that a task that uses finite verbs shows a strong correlation with communicative abilities in daily life. Also, we introduced and compared our standardized finite verb task in the operating theater and compared it with an object naming task. Our tests are currently and successfully used in different surgery wards in Italy and overseas. This work can be extended to other neurological populations such as stroke, dementias, and epilepsy.