Congratulations to first authors Diana Neacsu and Gabby Winters-Bostwick, whose papers are out today in Current Biology! These paired studies of the neuroanatomy of the octopus arm are funded by our Allen Distinguished Investigator grant, which has the broad aim of revealing organisation of nervous systems of less well-studied animals.
A 3D rendering of the ventral tracts of the octopus arm nerve cord, with connections to sucker ganglia ©CrookLab
Diana’s paper uses a large 3D-EM dataset to show previously uncharacterized organizational symmetry in successive ganglia of the arm. It has always been unclear how strictly organized the neural tissues are in the arm, and here we show that each ganglion is a reflection of the ones next to it, making a series of precise A/B patterned structures along the arm, associated with each sucker. She also shows that the oblique connectives, very small tracts previously only mentioned in a few studies, run around the arm in a spiral and potentially allow signal to travel along and around the arm without involvement of other neural centers. This paper is the first from her MS thesis, which also includes a full connectomic reconstruction of the sucker ganglion (hopefully coming soon!)
A cross section through the axial ganglion with neurons of different types labeled with different probes. ©CrookLab
Gabby’s paper uses the relatively new HCR method to label individual cells in the main axial ganglion according to their molecular identity. Using markers for multiple neuronal subtypes, she reveals stratification of cell types within the cord in the oral/aboral, L-R and distal-proximal axes, and shows highly complex co-expression profiles of cells that suggest many more subtypes than previously appreciated. This new information should greatly accelerate future physiological and functional studies of the arm.
Both papers produced high resolution, 3D maps of the octopus arm which can be viewed as animations (here featured at The Transmitter). The reconstruction of the two tissue volumes was a massive computational effort that provides unprecedented detail and new information about how octopus arms achieve their complex behavioral functions. We expect these datasets will inform future studies in our lab and those of others. These are the first two papers that come from the funding to our lab from the Allen Frontiers Group, and we are immensely grateful for their support of our work.