If you know what genes? and how its getting turned on? By what pathway? then you can use some inhibitor/activator molecule for that pathway...Or agonist/antagonist to test the expression of your genes. But this is indirect way...

the same question? what is the pathway? maybe you can use some inhibitors or activator of the genes? But in this way you never know if you affect only single pathway or you have some pleiotropic effect.

Behavioural study means you depend on complete animals that are observed over long timespans. So, all the nice techniques for manipulation of gene expression at the single cell or maybe embryo level or similar will not work (RNAi, morpholino oligomer analogues of complementary RNA). You will probably have no choice, other than using mutants. In that case, you must, however, be very clear about the gene that you suspect to influence the behavioural traits that you intend to study.

Newer genome editing strategies allow faster, easier generation of knockout mice. See, e.g.:

https://www.researchgate.net/publication/255715686

Article Heritable gene targeting in the mouse and rat using a CRISPR...

It depends on what behavioral trait you what to look at. To my knowledge, you can bypass knock out strategy by injecting rats or mice with virus encoding the shRNA which target your specific gene of interest. if you want to use this method, you should be aware of that you are looking at the specific region of that gene which might be related to that behavior you study.

You may also be able to utilize the cutting edge genomic editing technique such as CRISPR-Cas, TALEN. But for behavior study, you may need to double check whether the mice/ rats genrated by these methods are of the same genetic background. I'm not an expert on these techniques.

Johannes- TQ for your nice reminder. May I know your opinion, how do you determine that a gene could influence the behavior? In my case, there is no behavioral study with a complete knockout of this gene has been done.

Math&Magdalena- This gene involve in many pathways, as it encode a protein that play important roles in regulation of PKC. To my knowledge, there is no activators/inhibitors yet.

Hongtian- how fast the production using CRISPR-cas technique? How about the cost? thanks

I agree with Hongtian, do you have a microRNA expression vector (miRNA targeting your gene of interest) that you could use to generate an AAV (virus for stable knock down)?

If you are doing a behavioral study, you need to try to mimic what happens in real life and there are a number of factors to consider.

1) knockout models do not mimic what happens in in tact systems. Behavior is always complex and seldom the result of a single gene. I would suggest before focusing on a single gene that you do gene expression analyses to investigate patterns of gene expression, i.e.which genes are up- and down- regulated in the behaviors that you are investigating. You can use Ingenuity Pathway Analyses to help interpret your results.

2) the other ways to influence gene expression are epigenetic. Some of the animal models used for behavioral research have involved testing the effect of licking and grooming (nurturance behavior in mothers) on adult gene expression in the brain. Result: down regulation of activity in areas related to anxiety in adult brains of the offspring. Epigentic influences are many: nutrients, abuse, toxins, etc.