Uncovering the functional anatomy of the human insula during speech

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Abstract

The contribution of insular cortex to speech production remains unclear and controversial given diverse findings from functional neuroimaging and lesional data. To create a precise spatiotemporal map of insular activity, we performed a series of experiments: single-word articulations of varying complexity, non-speech orofacial movements and speech listening, in a cohort of 27 patients implanted with penetrating intracranial electrodes. The posterior insula was robustly active bilaterally, but after the onset of articulation, during listening to speech and during production of non-speech mouth movements. Preceding articulation there was very sparse activity, localized primarily to the frontal operculum rather than the insula. Posterior insular was active coincident with superior temporal gyrus, but was more active for self-generated speech than external speech, the opposite of the superior temporal gyrus. These findings support the conclusion that the insula does not serve pre-articulatory preparatory roles.

Data availability

Source data files and a MATLAB plotting function have been provided for Figures 2, 3, 5 and 6.

Article and author information

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Oscar Woolnough

Vivian L Smith Department of Neurosurgery, McGovern Medical School, University of Texas Health Houston, Houston, United States

For correspondence
oscar.woolnough@uth.tmc.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-5878-6865
Kiefer James Forseth

Vivian L Smith Department of Neurosurgery, McGovern Medical School, University of Texas Health Houston, Houston, United States

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0003-1624-8329
Patrick Sarahan Rollo

Vivian L Smith Department of Neurosurgery, McGovern Medical School, University of Texas Health Houston, Houston, United States

Competing interests
The authors declare that no competing interests exist.
Nitin Tandon

Vivian L Smith Department of Neurosurgery, McGovern Medical School, University of Texas Health Houston, Houston, United States

For correspondence
Nitin.Tandon@uth.tmc.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-2752-2365

Funding

National Institute on Deafness and Other Communication Disorders (DC014589)

Oscar Woolnough
Kiefer James Forseth
Patrick Sarahan Rollo
Nitin Tandon

National Institute of Neurological Disorders and Stroke (NS098981)

Oscar Woolnough
Kiefer James Forseth
Patrick Sarahan Rollo
Nitin Tandon

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: Patients participated in the experiments after written informed consent was obtained. All experimental procedures were reviewed and approved by the Committee for the Protection of Human Subjects (CPHS) of the University of Texas Health Science Center at Houston as Protocol Number: HSC-MS-06-0385

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.