Butterfly Brain

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Siddiqui, J. & Krishnan, A. S. Butterfly glioma. N. Engl. J. Med. https://doi.org/10.1056/NEJMicm1704713 (2018).

Yu, H. et al. LEPR hypomethylation is significantly associated with gastric cancer in males. Exp. Mol. Pathol. 116, 104493. https://doi.org/10.1016/j.yexmp.2020.104493 (2020). Hypervascularization of the tumor was noticed in glioma while there were no signs of flow void seen in lymphoma or germ cell tumors (Chi-square test, P< 0.001). Two-thirds (58.8%) of the hypervascular configurations were found in glioblastoma whereas the remaining configurations were diffuse astrocytoma (23.5%), anaplastic astrocytoma (11.8%), and gemistrocytic astrocytoma (5.9%). Almost half of tumor necrosis (44.8%) were observed in glioma and more than two-thirds (64.3%) had extensive necrosis (>50% of tumor size) in glioblastoma. While heading coding has been extensively studied in a variety of species 10, 55, 56, 57, 58, only little was known about goal direction coding 51. We here described the coding of GD neurons in the insect brain. The angular tuning of these neurons changed when the butterfly’s goal direction was reset (Fig. 2). More importantly, this change was tightly associated with the change in goal direction (Fig. 3g). In contrast to this, compass perturbations did not affect the angular tuning in the very same neurons (Fig. 3). This specific coding of the goal direction is well in line with very recent findings from the Drosophila brain 59 and confirms that the insect brain houses GD neurons similar to the ones previously discovered in the mammalian hippocampus 15. Consistent with our results, mammalian GD neurons did not represent heading information but were specifically tuned to the spatial goal. Some neurons in the mammalian hippocampus were additionally tuned to the goal distance 15, 21. Processing goal distance information is particularly important for vector navigation 26, 60 and for homing 61, 62. Recent results in the brain of a variety of insects show that the central complex additionally processes distance information 25, 63, making it highly likely that the insect GD neurons are also tuned to distance in the context of path-integration 64, 65, 66 or prey detection 63. Whether distance coding has any behavioral relevance in non-migratory or migratory monarch butterflies remains unclear. Like migratory birds, migratory monarch butterflies rely most likely on a stop signal rather than distance information to localize their migratory goal 67. Thus, it would not be surprising if the here described GD neurons in monarch butterflies do not encode distance information and purely encode directional information for short-distance dispersal (non-migratory) or long-distance migration (migratory).Angelaki, D. E. & Laurens, J. The head direction cell network: attractor dynamics, integration within the navigation system, and three-dimensional properties. Curr. Opin. Neurobiol. 60, 136–144 (2020). The outlook for a malignant brain tumour depends on things like where it is in the brain, its size, and what grade it is. Butterfly glioblastoma (bGBM) is a rare type of glioblastoma, a brain tumor that invades both hemispheres by crossing the corpus callosum, deriving its name from the shape of patterns it forms in MRI images. bGBM is associated with a poor prognosis with a median survival of 3.3–6 months 1, 2, 3, and only 9% of patients with bGBM survive 2-years 4. Guerra, P. A. & Reppert, S. M. Coldness triggers northward flight in remigrant monarch butterflies. Curr. Biol. 23, 419–423 (2013).

Medulla oblongata. This is the lowest part of the brainstem, which communicates directly with the spinal cord. The medulla oblongata contains important substructures called medullary pyramids, which, in turn, contain motor fibers that pass from the brainstem to the spinal cord. It controls vital autonomic processes such as the heartbeat and secretion of gastric substances.

Tenger-Trolander, A. & Kronforst, M. R. Migration behaviour of commercial monarchs reared outdoors and wild-derived monarchs reared indoors. Proc. Biol. Sci. 287, 20201326 (2020). Using complex and mysterious navigation mechanisms and travelling huge distances precisely with no map, with 3.5 cm wings and a brain of only a million neurons is an impressive feat. As a species, humans can struggle with navigation without maps despite having brains with 100 billion neurons, and as an individual member of that species I marvel at the feats of some of nature’s tiniest travellers as I continue to search park maps for the arrow saying ‘you are here’.