Linguistic Specificity of the Left Temporal Cortex: Iintraoperative Mapping Data

The present study sought to test two hypotheses. First, that the standard intraoperative object naming task is not sufficient to test all the functionally essential areas in the left temporal lobe. Second, the hypothesis that phonological and lexical circuits in the left temporal lobe can be anatomically disassociated. In the introductory part of the study we described the awake surgery procedure, classical and contemporary neurological models, and the existing information about the left temporal lobe. In the course of the study, we collected and analyzed the data from intraoperative brain mapping of 25 patients with brain lesions – gliomas or pharmacoresistant epilepsy, who underwent awake craniotomy. All the patient went through intraoperative language mapping with the use of direct electrical stimulation. In order to map phonological and lexical processing circuits, in addition to the classical object naming task, two additional tasks, the phonological judgment task and word-picture matching task were used. The results showed substantial dissociation between mapping of different tasks. According to these findings, we can conclude that the object naming task alone is not suitable for adequate brain mapping of the left temporal cortex. The same dissociation may be regarded as an argument in favor of the anatomical dissociation of the phonological and lexical circuits. However, more data is needed to make definite conclusion.