Functional differences among stimulation-identified cortical naming sites in the temporal region. Epilepsy Behav 2016 Jul;60:124-129
Date
05/21/2016Pubmed ID
27206230Pubmed Central ID
PMC4912888DOI
10.1016/j.yebeh.2016.04.021Scopus ID
2-s2.0-84969242500 (requires institutional sign-in at Scopus site) 17 CitationsAbstract
To preserve postoperative language, electrical stimulation mapping is often conducted prior to surgery involving the language-dominant hemisphere. Object naming is the task most widely used to identify language cortex, and sites where stimulation elicits naming difficulty are typically spared from resection. In clinical practice, sites classified as positive undergo no further testing regarding the underlying cause of naming failure. Word production is a complex function involving multiple mechanisms that culminate in the identification of the target word. Two main mechanisms, i.e., semantic and phonological, underlie the retrieval of stored information regarding word meaning and word sounds, and naming can be hampered by disrupting either of these. These two mechanisms are likely mediated by different brain areas, and therefore, stimulation-identified naming sites might not be functionally equivalent. We investigated whether further testing at stimulation-identified naming sites would reveal an anatomical dissociation between these two mechanisms. In 16 patients with refractory temporal lobe epilepsy (TLE) with implanted subdural electrodes, we tested whether, despite inability to produce an item name, patients could reliably access semantic or phonological information regarding objects during cortical stimulation. We found that stimulation at naming sites in superior temporal cortex tended to impair phonological processing yet spared access to semantic information. By contrast, stimulation of inferior temporal naming sites revealed a greater proportion of sites where semantic access was impaired and a dissociation between sites where stimulation spared or disrupted semantic or phonological processing. These functional-anatomical dissociations reveal the more specific contribution to naming provided by these cortical areas and shed light on the often profound, interictal word-finding deficit observed in temporal lobe epilepsy. Additionally, these techniques potentially lay the groundwork for future studies to determine whether particular naming sites that fall within the margins of the desired clinical resection might be resected without significant risk of decline.
Author List
Hamberger MJ, Miozzo M, Schevon CA, Morrison C, Carlson C, Mehta AD, Klein GE, McKhann GM 2nd, Williams ACAuthor
Chad Carlson MD Professor in the Neurology department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
AdolescentAdult
Brain Mapping
Electric Stimulation
Electrodes, Implanted
Epilepsy, Temporal Lobe
Female
Humans
Language
Male
Middle Aged
Names
Psycholinguistics
Psychomotor Performance
Semantics
Temporal Lobe
Young Adult
