Neuroanatomy of the grey seal brain:
bringing pinnipeds into the neurobiological study of vocal learning
Nienke Hoeksema cs 2021 doi org/10.1098/rstb.2020.0252

Comparative animal studies of complex behavioural traits + their neuro-biological underpinnings can increase our understanding of their evolution, incl. in Hs.
VL (a precursor to human speech?) is one such trait.
Mammalian VL is under-studied: most research has either focused on VL in songbirds, or its absence in non-human primates.

Here, we focus on a highly promising model species for the neuro-biology of VL: Halichoerus grypus.
We provide a neuro-anatomical atlas (based on dissected brain slices & MRI), a labelled MRI-template, a 3D-model with volumetric measurements of brain regions & histol.cortical stainings.

4 main features of the grey seal brain stand out:
(i) it is rel.big, and highly convoluted;
(ii) it hosts a rel.large temporal lobe & cerebellum;
(iii) the cortex is similar to Hs in thickness, and shows the expected 6-layered mammalian structure;
(iv) there is expression of FoxP2 present in deeper layers of the cortex (FoxP2 is a gene involved in motor learning, VL & spoken language).

Our results could facilitate future studies targeting the neural & genetic underpinnings of mammalian VL, bridging the research gap from songbirds to Hs & non-Hs primates.
Our findings are relevant not only to VL, research but also to the study of mammalian neuro-biology & cognition more in general.

Concl.
we provide a first investigation into the neuro-anatomy of the grey seal brain, using infm from dissected brain sections & MRI:
we were able to
- create a neuro-anatomical reference atlas, a standard brain template & 3D models of the weaned grey seal brain,
- get a first glimpse of the neuro-genetic properties of the grey seal brain.
Based on the neuro-anatomical infm & brain templates provided here, future comparative studies of VL in grey seals could employ techniques such as genetic mapping, or diffusion tensor imaging, to test hypotheses re.the necessary & sufficient neural circuits involved in mammalian VL.

IOO, the study of VL pinnipeds will be quintessential to a complete understanding of the neuro-biology of VL:
as mammals, they can help bridge the gap from research in songbirds to research in Hs & non-Hs primates.