Seal and sea lion brains have evolved to support volitional control of vocal behavior and learning

Data files

Feb 17, 2026 version files 7.48 GB

CSL_ES_HS_Coy_Struc_dMRI_Cook.tar.gz

7.48 GB
README.md

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Abstract

Seals and sea lions have highly developed volitional breathing control, to which the phocid seals add vocal production learning, including mimicry. Here, using histology and ex vivo dMRI tractography, we provide evidence for a phylogenetic spectrum of accumulative neural adaptations supporting aspects of volitional vocal control across pinnipeds. Otariids and phocid seals, but not coyotes, have a direct connection between vocal motor cortex and phonatory brainstem nuclei. Harbor seals showed hypertrophic connectivity between anterior ventrolateral thalamus and vocal premotor cortex, part of a forebrain circuit related to vocal learning in birds and mimicry in humans and parrots. We argue that Phocid seals have auditory-premotor pathways potentially related to developmental call learning.

Dataset DOI: 10.5061/dryad.h44j0zq13

Description of the data and file structure

These post-mortem structural and steady-state diffusion magnetic resonance imaging data were collected to support comparative analyses of brain pathways in pinnipeds and terrestrial carnivores. The data are high-resolution (sub mm) structural MR images in nifti format, either trufi or T2, and diffusion data, including a b0 structural and the x_bedpost.bedpostX folder generated by fsl's bedpostX analysis pipeline. Specific to the work on pinniped vocal neurobiology, there are also nifti ROI files for each subject. The bedpost data can be used for ROI/seed-based probabilistic tractography.

Files and variables

File: CSL_ES_HS_Coy_Struc_dMRI_Cook.tar.gz

Description: The data directories are zipped in a tar.gz file. This can be unzipped by double clicking in Linux or in Windows environment with 7z or an analogous program.

There are five directories included: coyotes, elephant_seals, harbor_seals, sea_lions, and MRData. The individual study subject structural and diffusion data are in individual directories within the species directories. Each individual subject directory contains the x_bedpost.bedpostX folder with all the outputs from fsl's bedpostx analysis pipeline, a b0 diffusion-space structural image, a higher resolution trufi or T2 structural image, and the transformation matrix between high-res and diffusion space. For one elephant seal there is no high-resolution structural image.

The MRData directory contains text files with subject ID information (BrainIDs) and an ROI region name key (RegionKey). It also contains individual directories for each study subject with codes matching those in the species diffusion data folders.

Each individual subject directory in MRData contains the regions of interest used as seeds in the probabilistic tractography analyses in the related paper. These are the same regions for each subject, and follow the codes in RegionKey.txt. All ROIs are nifti files and are in high resolution structural space except for those of elephant seal ES3, which has no high resolution structural. All of this subject's ROI files are in diffusion space.

Code/software

The structural data and ROI data are standard nifti files and can be viewed in any nifti image viewer. We predominantly use the fsleyes image viewer from fsl (https://fsl.fmrib.ox.ac.uk/fsl/docs/install/index.html), which has a simple gui for loading and viewing nifti images. However, that is designed for the Linux environment. Many other softwares will work. ITKSnap is commonly used and has a Windows distribution. The diffusion data are also saved as nifti files, however, some of the bedpost data need specific modulation options for appropriate viewing, such as the 3D vector overlay viewing option in fsleyes for dyads files (which contain the voxel-wise diffusion direction data from the bedpost model). Any image viewing program appropriate for viewing vector/diffusion imaging data will work.

Access information

Other publicly accessible locations of the data:

Our data are hosted along with other comparative structural and diffusion neuroimaging datasets at Oxford University's Digital Brain Bank: https://open.oxcin.ox.ac.uk/DigitalBrainBank/#/
We recommend acquiring the data from there, as this allows connecting with other comparative researchers who can support use of the data for further science.