Question: How and why do hormones change behavior?

Elaine Marshall answered on 18 Jun 2013:

At the simplest level hormones have an effect on our behavior by altering how our brain functions.

As cells release hormones in response to an event or environmental trigger, once these hormones hit target cells they trigger a response. If it happens that the brain is one of the targets (as it has the appropriate receptor) then the brain cells will respond to the hormonal signal. When a hormone binds to a receptor is will bring about a rapid change in the cell for example – open or close channels, release of a substance or sometimes also change gene expression within that cell (switch on/off). All of these changes can bring about large changes in function for some brain cells which may directly change how we behave.

For example when the brain is exposed to oxytocin (as during labour) nerve cells are triggered to establish new connections (the cells are effectively rewired!) and this is thought to promote maternal behavior in the mother. A few years ago there was also a study which showed that during puberty, the brains of teenagers functioned differently under physcological testing compared to young adults or prepubescent children. Specifically teenagers found it difficult to recognise emotions in others – which may explain alot……Also there is well documented evidence that cortisol and testosterone effect mood and behavior and again this is due to how nerve cells in the brain respond to the circulating hormones.