Mapping quantal touch using 7 Tesla functional magnetic resonance imaging and single-unit intraneural microstimulation

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Abstract

Using ultra-high field 7 Tesla (7T) functional magnetic resonance imaging (fMRI), we map the cortical and perceptual responses elicited by intraneural microstimulation (INMS) of single mechanoreceptive afferent units in the median nerve, in humans. Activations are compared to those produced by applying vibrotactile stimulation to the unit's receptive field, and unit-type perceptual reports are analyzed. We show that INMS and vibrotactile stimulation engage overlapping areas within the topographically appropriate digit representation in the primary somatosensory cortex. Additional brain regions in bilateral secondary somatosensory cortex, premotor cortex, primary motor cortex, insula and posterior parietal cortex, as well as in contralateral prefrontal cortex are also shown to be activated in response to INMS. The combination of INMS and 7T fMRI opens up an unprecedented opportunity to bridge the gap between first-order mechanoreceptive afferent input codes and their spatial, dynamic and perceptual representations in human cortex.

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Rosa Maria Sanchez Panchuelo

Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom

For correspondence
rosa.panchuelo@nottingham.ac.uk

Competing interests
The authors declare that no competing interests exist.
Rochelle Ackerley

Department of Physiology, University of Gothenburg, Göteborg, Sweden

Competing interests
The authors declare that no competing interests exist.
Paul M Glover

Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Richard W Bowtell

Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Johan Wessberg

Department of Physiology, University of Gothenburg, Göteborg, Sweden

Competing interests
The authors declare that no competing interests exist.
Susan T Francis

Sir Peter Mansfield Imaging Centre, School of Physics and Astronomy, University of Nottingham, Nottingham, United Kingdom

Competing interests
The authors declare that no competing interests exist.
Francis McGlone

School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom

Competing interests
The authors declare that no competing interests exist.

Ethics

Human subjects: This work was approved by the University of Nottingham Medical School Ethics Committee. All participants gave full, written, informed consent.

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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.