Functional representation of trigeminal nociceptive input in the human periaqueductal gray

The periaqueductal gray (PAG) is located in the mesencephalon in the upper part of the brainstem and as part of the descending pain modulation is considered a crucial structure for pain control. Its modulatory effect on painful sensation is often seen as a systemic function affecting the whole body similarly. However, recent animal data suggest some kind of somatotopy in the PAG. This would make the PAG capable of dermatome-specific analgesic function. We electrically stimulated the peripheral dermatomes of the trigemino-cervical complex consisting the three branches of the trigeminal nerve and the greater occipital nerve in sixty-one humans during optimized brainstem fMRI. We provide evidence for a fine-grained and highly specific somatotopic representation of nociceptive input in the PAG in humans and a descending functional connectivity between the individual representations of the peripheral nerves in the PAG and the brainstem nuclei of these nerves. Our data suggest that the downst..., Sixty-three healthy, right-handed volunteers participated in our study on repetitive, randomize, peripheral, painful electrical stimulation of the three trigeminal branches (V1, V2, V3) innervating the facial dermatomes and the greater occipital nerve (GON) which innervates the back of the head (Figure 1B in the related publication). For the primary outcomes, (confirmation of earlier studies showing somatotopic representation for the insula, thalamus etc) which are not part of this manuscript, we initially measured 25 participants for hypothesis-generation. Power calculations revealed that 36 participants were needed to reproduce the hypothesized results. As the results in the PAG, which we present here, are preregistered as secondary outcome we combined both groups for a robust outcome resulting in 63 participants. Two volunteers of the second cohort had to be excluded due to technical problems, leaving 61 (27 male, age: 28.51 +/- 9.4) for the further analysis. All participants were fr..., , # Functional representation of trigeminal nociceptive input in the human periaqueductal gray

[https://doi.org/10.5061/dryad.mw6m90642](https://doi.org/10.5061/dryad.mw6m90642)

## Description of the data and file structure

This dataset consists of processed images from functional magnetic resonance imaging (fMRI) in NIFTI-format readable by common MRI viewing and analyzing software like Mango ([https://mangoviewer.com/](https://mangoviewer.com/), MRIcron ([https://www.nitrc.org/projects/mricron](https://www.nitrc.org/projects/mricron) or SPM12 ([https://www.fil.ion.ucl.ac.uk/spm/software/spm12/](https://www.fil.ion.ucl.ac.uk/spm/software/spm12/)). The images of this dataset were created using the SPM12 toolbox.

For each of the 61 subjects there is a folder containing 8 images:

·        con0003.nii refers to neuronal activity occurring in the brain by stimulating the first trigeminal branch (V1),

·        con0004.nii refers to neuronal activity occurring in the brain by stimulating ...