Temporal lobe stimulation reveals anatomic distinction between auditory naming processes.
BACKGROUND
Language errors induced by cortical stimulation can provide insight into function(s) supported by the area stimulated. The authors observed that some stimulation-induced errors during auditory description naming were characterized by tip-of-the-tongue responses or paraphasic errors, suggesting expressive difficulty, whereas others were qualitatively different, suggesting receptive difficulty. They hypothesized that these two response types reflected disruption at different stages of auditory verbal processing and that these "subprocesses" might be supported by anatomically distinct cortical areas.


OBJECTIVE
To explore the topographic distribution of error types in auditory verbal processing.


METHODS
Twenty-one patients requiring left temporal lobe surgery underwent preresection language mapping using direct cortical stimulation. Auditory naming was tested at temporal sites extending from 1 cm from the anterior tip to the parietal operculum. Errors were dichotomized as either "expressive" or "receptive." The topographic distribution of error types was explored.


RESULTS
Sites associated with the two error types were topographically distinct from one another. Most receptive sites were located in the middle portion of the superior temporal gyrus (STG), whereas most expressive sites fell outside this region, scattered along lateral temporal and temporoparietal cortex.


CONCLUSIONS
Results raise clinical questions regarding the inclusion of the STG in temporal lobe epilepsy surgery and suggest that more detailed cortical mapping might enable better prediction of postoperative language decline. From a theoretical perspective, results carry implications regarding the understanding of structure-function relations underlying temporal lobe mediation of auditory language processing.
Department of Neurology, College of Physicians and Surgeons, Columbia University, New York, USA. mh61@columbia.edu
M J
MJ
Hamberger
W T
WT
Seidel
R R
RR
Goodman
K
K
Perrine
G M
GM
McKhann
D000161:Acoustic Stimulation; D000328:Adult; D038481:Anterior Temporal Lobectomy / Q000379:methods; D001931:Brain Mapping; D004292:Dominance, Cerebral; D004558:Electric Stimulation; D004833:Epilepsy, Temporal Lobe / Q000473:pathology / Q000503:physiopathology / Q000601:surgery; D005260:Female; D006801:Humans; D007802:Language; D007806:Language Disorders / Q000517:prevention & control; D007807:Language Tests; D008297:Male; D008875:Middle Aged; D009275:Names; D011183:Postoperative Complications / Q000517:prevention & control; D011300:Preoperative Care; D012189:Retrospective Studies; D013702:Temporal Lobe / Q000503:physiopathology / Q000648:ultrastructure*; D014705:Verbal Behavior / Q000502:physiology*