Animals will often explore a new environment if they have the chance. Crusio thought that this would be favorable. he thought it would make it possible for animals to find water, food, etc. However, moving around in unfamiliar spaces is dangerous. Such stabilizing selection would leave genetic traces. Crusio did indeed find such traces for mice and for Paradise fish.
Hippocampal mossy fibers
In Heidelberg, Crusio became interested in the inheritance of variations in the neuroanatomy of the mouse hippocampus. He studied the intra- and infrapyramidal mossy fiber (IIPMF) projections in this brain area. Crusio showed that about 50% of the variation found between different inbred mouse strains in the sizes of their IIPMF were due to genetic differences. Herbert Schwegler and Hans-Peter Lipp had found that these variations are correlated with learning a two-way active avoidance task. Animals with smaller projections learned much faster than animals with larger IIPMF. Together with Schwegler and Lipp, Crusio showed that an inverse correlation could be found for spatial learning in a radial arm maze task. Animals with larger IIPMF learned better in this task. Injecting mouse pups with thyroxine results in larger IIPMF projections. When mice from a strain with small IIPMF projections zere treated in this way, they could learn better in the radial maze. Crusio and his collaborators think that this correlation is causal. Not everybody believes this.
Mouse model of depression
Mice that suffer unpredictable chronic mild stress (UCMS) show symptoms that look like depression in humans. Researchers were thinking that deficits in hippocampal neurogenesis (the birth of new nerve cells) might be the cause of depression. Crusio and collaborators did experiments to look at changes in behavior and neurogenesis in stressed mice. They showed large changes in levels of aggression, anxiety, depressive-like behaviors, and learning. At the same time, there was a large drop in neurogenesis. The results dependent very much on the strain and sex. There did not appear to be a clear-cut correlation between the different changes. They concluded that their data do not support the idea that deficits in hippocampal neurogenesis alone are the cause of depression. However, they do not disprove this hypothesis either.
Mouse model of autism
Crusio has recently looked into the possibility that FMR1knockout mice can perhaps be used as a model for autism. The Fragile X syndrome is caused by a deficiency of the FMR1 gene. Patients often show autistic symptoms. A good mouse model for the Fragile X syndrome is available because there are mice in which the Fmr1 gene has been changed so that it does not work any more. A review of the work that has been done with these mice in many different laboratorie did indeed show that these animals have autistic-like symptoms. For example, they show changes in social behavior and this is a key symptom of autism.
Crusio was one of two co-founders of the International Behavioural and Neural Genetics Society in 1996 He served as member-at-large of the executive committee, treasurer, and president (1998–2001) of this society. He received from this society in 2011 the "Distinguished Service Award" for exceptional contributions to the field of behavioral neurogenetics. Crusio also served on the executive committees of the Behavior Genetics Association (from which he resigned in protest to Glayde Whitney's 1995 presidential address), the European Brain and Behaviour Society, and the International Behavioral Neuroscience Society (IBNS). Crusio has been a President of the Dutch Behavior Genetics Contact Group. He has been a member of several program committees for scientific meetings, most notably the 8th and 10th World Congresses of Psychiatric Genetics and the 2008, 2009 (co-chair), 2010 (chair), and 2011 (chair) Annual Meetings of the IBNS.
Important papers
According to the Web of Science, Crusio's articles have been cited over 3200 times and he has an h-index of 33. Some important papers are:
Crusio WE, Genthner-Grimm G, Schwegler H (2007). "A quantitative-genetic analysis of hippocampal variation in the mouse". Journal of Neurogenetics. 21 (4, Special Retrospective Issue: The Origins of Neurogenetics): 197–208. doi:10.1080/01677060701715827. PMID18161583. S2CID7334116.{{cite journal}}: CS1 maint: multiple names: authors list (link) Original publication: Crusio, W. E.; Genthner-Grimm, G; Schwegler, H (July 1986). "A Quantitative-Genetic Analysis of Hippocampal Variation in the Mouse". Journal of Neurogenetics. 3 (4): 203–214. doi:10.3109/01677068609106850. PMID3746523.
↑Crusio, W. (1979). "A revision of Anubias Schott (Araceae). (Primitiae Africanae XII)". Mededelingen Landbouwhogeschool Wageningen. 79 (14): 1–48.
↑Sykora, KV (1984). "A synecological study of the Lolio-Potentillion anserinae Tuexen 1947 by means of permanent transects. II: Riverine eurysaleutic habitats". Proceedings of the Koninklijke Nederlandse Akademie van Wetenschappen. Series C, Biological and Medical Sciences. 87 (2): 181–230.
↑Crusio WE (20 February 1982). "Het geslacht Samolus L.". Communications of the Dutch Waterplant Society (in Dutch). 2: 13–25.
↑Crusio WE (26 May 1984). "Notes on the genus Samolus L. (Primulaceae)". Communications of the Dutch Waterplant Society. 6: 13–16.
↑Crusio W.E. and de Graaf A. (April 1986). "Lagenandra dewitii Crusio et de Graaf (Araceae), eine neue Art aus Sri Lanka". Aqua Planta (in German). 11 (2): 56–59.
↑Crusio, WE (1984). Olfaction and behavioral responses to novelty in mice: A quantitative-genetic analysis. Meppel: Krips Repro. pp.viii+146+78.
↑"Crusio Wim". The Aquitaine Institute for Cognitive and Integrative Neuroscience. Archived from the original on 21 October 2014. Retrieved 29 December 2012.
"Crusio Wim". Homepage. The Aquitaine Institute for Cognitive and Integrative Neuroscience. Archived from the original on 21 October 2014. Retrieved 12 January 2012.