Biological analysis of woodpecker’s brain after impact experiments

• Published in: Science China. Technological sciences Vol. 64; no. 5; pp. 1101 - 1106
• Main Authors: Xu, Peng, Ni, YiKun, Liu, JingLong, Zhang, WeiRong, Liu, SiJian, Wang, LiZhen, Fan, YuBo
• Format: Journal Article
• Language: English
• Published: Beijing Science China Press 01.05.2021; Springer Nature B.V
• Subjects: Apoptosis; Biological effects; Biomechanical engineering; Biomechanics; Brain; Cerebellum; Engineering; Experiments; Forehead; Impact analysis; Impact resistance; Injury analysis; Morphology; Proteins; Staining; woodpecker; biological analysis; biomechanics; impact experiments; impact resistance
• ISSN: 1674-7321; 1869-1900
• DOI: 10.1007/s11431-020-1754-0

Woodpeckers can withstand a fierce impact during pecking. Previous studies have focused on the biomechanical analysis of the pecking process, the properties of the beak and hyoid bone of woodpecker; however, the biological characteristics of the woodpecker brain are also important in resisting impact injuries. We employed impact experiments and biological analysis in normal and injured brains to reveal the impact-resistant biological characteristics of woodpecker brains, as well as the impact energy’s biological effects on the woodpecker brain. The hoopoe, which has a similar size but only a slight pecking behavior, was selected as the control group to compare brain morphology and neuronal cells differences in normal brains between woodpecker and hoopoe by sectioning and staining. A loading device was designed to conduct a quantifiable impact energy to the woodpeckers’ head. Four groups of woodpeckers were impacted with the same energy on the forehead, beak, tempus and occiput, respectively. Biological changes in the injured brains were evaluated by Nissl staining and enzyme-linked immunosorbent assay. The results showed that: (1) woodpeckers had a larger cerebellum and a higher density of Nissl bodies than hoopoe; (2) Nissl apoptosis appeared in the brain samples after the forehead and the occiput impact experiments, but no obvious Nissl body apoptosis was observed after impact on the tempus and the beak; (3) β-amyloid protein accumulated in the normal status woodpecker brain. This study reveals that: woodpecker brain morphology is well-adapted to impact, woodpecker heads display location-dependent protective performance, with beak and tempus regions having a better protective performance than the forehead and occiput, Nissl apoptosis appears in injured woodpecker brains, and that the accumulation of β-amyloid protein does not show a direct relationship with the injury state of woodpecker’s brain tissue in our study.