The Neurobehaviour Core



Mice are social animals. Many aspects of their expression of behavioural phenotypes depends on their sociability. Social behaviour is expressed at different levels of mouse development, starting with juvenile playful behaviour, sexual behaior, parental behaviour, intermale aggression with establishment of population hierarchy, etc. Sociability is a gene and environment dependent form of behaviour, and careful examination of sociability in gene-modified mice under standard laboratory conditions is a helpful tool in identifiying various genes involved in the regulation of different aspects of social behaviour.

Our neurobehaviour core offers several tests including social interactions of mice in the neutral area, social affiliation and novelty, resident-intruder, estimating social motivation, social memory, and level of passive or active submissive-aggressive behaviour.

Complex investigation of your mouse in differernt situations can help build a comprehensive ethogram, which can hopefully reveal new functions of the studied gene.


Social Interactions



Following a 5 minute adaptation period (subject is free to explore all three chambers), an unfamiliar mouse (male C57BL/6J, "stranger 1") is placed inside a cylinder positioned in one of the side chambers. Containing the stranger mouse in the cylinder ensures that a social approach is initiated by the subject mouse and is investigatory only, without direct physical contact. Time spent by the test mouse in each chamber is recorded over a 10 minute period.

Another unfamiliar mouse ("stranger 2") is then placed inside an identical cylinder in the opposite side chamber, and the activity of the test mouse is again recorded for additional 10 minutes.

The test mouse is considered to physically be in the chamber when at least its head and two front paws are inside of that very same chamber. All behavioural events are video recorded and analyzed by Ethovision software (Noldus).



Figure 1. Social interactions


Neutral Area



A pair of male mice are used for this test. Each mouse is placed in an illuminated (280 lux) and unfamiliar neutral cage (30 x 17 x 12 cm), and social interactions are scored every time a test mouse approaches his weight and age matched, unfamiliar adult C57BL/6 male counterpart. Standard opponents are used only once and the neutral cage is changed for each mouse pair.

The observation period starts with the first interaction and lasts for 5 minutes. Social investigation (including stretched-attend posture, sniffing of a partner following genital grooming), flight (as an active avoidance of partner), freezing (passive sitting with slight movements of head), aggression (threat, attack, bite, chase), aggressive grooming and non-social behaviour (such as self-grooming, cage exploration, digging and rearing) are recorded.



Figure 1.Neutral Area




Males are housed individually for at least 1 week before testing. Observation begins once intruders (unfamiliar, socially housed C57BL/6J male mice, age and weight matched with each resident) are individually placed into the resident's home cage and lasts for 10 minutes.

Latency, duration and number of events are recorded as: aggressive behaviour (contact between the resident and the intruder such as biting or wrestling and aggressive grooming of partner) or social interest behaviour (following and sniffing of a partner).

A different intruder animal is used for each resident. Animals that do not attack the intruder are given an attack latency of 10 minutes.






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