The number of neurons in specific amygdala regions is associated with boldness in mink: a study in animal personality
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Conspecifics vary consistently in their behavioural responses towards environment stimuli such as exposure to novel objects; ethologists often refer to this variability as animal personality. The neurological mechanisms underlying animal personality traits remain largely unknown, but linking the individual variation in emotional expression to brain structural and neurochemical factors is attracting renewed interest. While considerable research has focused on hormonal and neurotransmitter effects on behavioural responses, less is known about how individual variation in the number of specific neuron populations contributes to individual variation in behaviour. The basolateral amygdala (BLA) and the central nuclei of the amygdala (CeA) mediate emotional processing by regulating behavioural responses of animals in a potentially threatening situation. As such, these structures are good candidates for evaluating the relationship between neuronal populations and behavioural traits. We now show that individual American mink (Neovison vison) reacting more boldly towards novelty have more neurons in the BLA than do their more timid conspecifics, suggesting that a developmental pattern of the number of amygdala neurons can influence behavioural traits of an adult animal. Furthermore, post hoc correlations revealed that individuals performing with higher arousal, as reflected by their frequency of startle behaviour, have more CeA neurons. Our results support a direct link between the number of neurons in amygdala regions and aspects of animal personality.
KeywordsAnimal personality Amygdala Stereology Mink
We thank Inglewood Biomedical Editing for expert assistance in preparing the manuscript, and Susanne Sørensen at the Research laboratory for Stereology and Neuroscience for expert technical assistance on histological handling of the tissue.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
Research involving animals
All procedures performed in studies involving animals were in accordance with the ethical standards of the institution or practice at which the studies were conducted.
This article does not contain any studies with human participants performed by any of the authors.
- Bear MF, Connors BW, Paradiso MA (2007) Neuroscience: exploring the brain. 3rd edn. Lippincott Williams & Wilkins, PhiladelphiaGoogle Scholar
- DiStefano C, Zhu M, Mîndrilǎ D (2009) Understanding and using factor scores: considerations for the applied researcher. Pract Assess Res Eval 14(20)Google Scholar
- Hershberger SL (2005) Factor scores. In: Everitt BS, Howell DC (eds) Encyclopedia of statistics in behavioral science. Wiley, New York, pp 636–644Google Scholar
- Kosmal A, Nitecka L (1977) Cytoarchitecture and acetylcholinesterase activity of the amygdaloid nuclei in the dog. Acta Neuro Biol Exp 37:363–374Google Scholar
- Mai JK, Voss T, Paxinos G (2007) Atlas of the human brain. http://www.thehumanbrain.info
- Matsunaga M (2015) How to factor-analyze your data right: do’s, don’ts, and how-to’s. Int J Physchol Res 3(1):97–110Google Scholar
- Noer CL, Needham EK, Wiese A-S, Dabelsteen T (2015) Context matters: Multiple novelty tests reveal different aspects of shyness–boldness in farmed American Mink (Neovison vison). PLoS One 10(6) https://doi.org/10.1371/journal.pone.0130474
- Noer CL, Needham EK, Wiese A-S, Balsby TJS, Dabelsteen T (2016) Personality matters: consistency of inter-individual variation in shyness–boldness across non-breeding and pre-breeding season despite a fall in general shyness levels in farmed American mink (Neovison vison). Appl Anim Behav Sci 181:191–199CrossRefGoogle Scholar