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Poster A43, Wednesday, November 8, 10:30 – 11:45 am, Harborview and Loch Raven Ballrooms

Dissociating the roles of ventral versus dorsal pathways in language production: an awake language mapping study

Stephanie Ries1, Vitoria Piai2,3, David Perry4, Sandon Griffin5, Kesshi Jordan6,7, Robert Knight5, Mitchel Berger4;1School of Speech, Language, and Hearing Sciences & Center for Clinical and Cognitive Neuroscience, San Diego State University, San Diego, CA, USA., 2Donders Centre for Cognition, Radboud University, Nijmegen, The Netherlands., 3Department of Medical Psychology, Radboud University Medical Centre, Nijmegen, The Netherlands., 4Department of Neurological Surgery, University of California, San Francisco, CA, USA., 5Helen Wills Neuroscience Institute and Department of Psychology, University of California at Berkeley, Berkeley, CA, USA., 6Department of Neurology, University California, San Francisco, CA, USA., 7UC Berkeley - UCSF Graduate Program in Bioengineering, San Francisco, CA, USA.

The neural basis for human language is thought to be organized along two main processing streams connecting the posterior temporal cortex to the inferior frontal cortex in the left hemisphere: one travelling dorsal, and the other travelling ventral to the Sylvian fissure. The roles of these two streams have been subject to debate. Some views propose a perception/production division (Hickok & Poeppel, 2007), and others propose a division along different types of combinatorial mechanisms (the dorsal stream being associated with the ability to combine elements into a sequence, the ventral with the formation of dependencies independent of sequential order and thus associated with semantics, Bornkessel-Schlesewsky, Schlesewsky, Small, & Rauschecker, 2015). However, the causal roles of dorsal and ventral white matter pathways associated with language production have yet to be specified. Here, we present data acquired through direct cortical electrical stimulation and subcortical resection during awake language mapping in 18 neurosurgical patients prior to and during tumor resection. Of the 18 patients, 17 were stimulated cortically and 10 were tested during subcortical resection in one or both of our tasks. Our 2 language tasks were designed to test the roles of the ventral and dorsal streams in language production. We used a picture-word interference (PWI) task manipulating semantic interference (the picture to be named and the superimposed distractor word were either semantically-related or semantically-unrelated); and a sentence generation task testing the ability to form sequential dependencies. We analyzed accuracy rates using logistic mixed effect models and deviance table analysis to test for fixed effects of Task, Stream (ventral or dorsal), and their interaction. There was no effect of Task, Stream (dorsal vs. ventral), nor interaction between Task and Stream during cortical stimulation. During subcortical testing, there was a main effect of Task: the sentence generation task elicited more errors than the PWI task. Critically, there was also an interaction between Task and Stream: when tumor resection was performed in the territory of dorsal stream pathways (i.e., the superior longitudinal fasciculus or the arcuate fasciculus), the sentence generation task elicited more errors compared to the PWI task. Whereas when tumor resection was performed in the territory of ventral stream pathways (i.e., the inferior fronto-occipital fasciculus or the uncinate fasciculus), there was no significant difference between tasks. Our results support a dorsal/ventral role division for white matter pathways involved in language production. In agreement with the model proposed by (Bornkessel-Schlesewsky et al., 2015), our results support that dorsal stream pathways are critical for organizing elements in a sequence, which is particularly needed in the generation of sentences, and that ventral stream pathways are critical for the processing of meaning dependencies, involved in both the picture-word interference and sentence generation tasks.

Topic Area: Meaning: Lexical Semantics

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