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Research article - Peer-reviewed, 2022

Proportional Cerebellum Size Predicts Fear Habituation in Chickens

Stingo-Hirmas, Diego; Cunha, Felipe; Cardoso, Rita France; Carra, Laura G.; Roennegard, Lars; Wright, Dominic; Henriksen, Rie;


The cerebellum has a highly conserved neural structure across species but varies widely in size. The wide variation in cerebellar size (both absolute and in proportion to the rest of the brain) among species and populations suggests that functional specialization is linked to its size. There is increasing recognition that the cerebellum contributes to cognitive processing and emotional control in addition to its role in motor coordination. However, to what extent cerebellum size reflects variation in these behavioral processes within species remains largely unknown. By using a unique intercross chicken population based on parental lines with high divergence in cerebellum size, we compared the behavior of individuals repeatedly exposed to the same fear test (emergence test) early in life and after sexual maturity (eight trials per age group) with proportional cerebellum size and cerebellum neural density. While proportional cerebellum size did not predict the initial fear response of the individuals (trial 1), it did increasingly predict adult individuals response as the trials progressed. Our results suggest that proportional cerebellum size does not necessarily predict an individual's fear response, but rather the habituation process to a fearful stimulus. Cerebellum neuronal density did not predict fear behavior in the individuals which suggests that these effects do not result from changes in neuronal density but due to other variables linked to proportional cerebellum size which might underlie fear habituation.


emergence test; behavioral predictability; domestication; neural density; isotropic fractionation

Published in

Frontiers in Physiology

2022, volume: 13, article number: 826178

Authors' information

Stingo-Hirmas, Diego
Linköping University
Cunha, Felipe
Linköping University
Cardoso, Rita France
Linköping University
Carra, Laura G.
Linköping University
Dalarna University
Swedish University of Agricultural Sciences, Department of Animal Breeding and Genetics
Wright, Dominic
Linköping University
Henriksen, Rie
Linköping University

UKÄ Subject classification

Medical Bioscience
Animal and Dairy Science

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