Testosterone has a crucial, if poorly understood, effect on male behaviour. It contributes to aggressivenes, libido, tumescence and sexual performance. Some scientists believe that the ratio of index finger length to ring finger length indicates how much testosterone we were exposed to in our mother’s womb. This has led some Palm reader’s to use clues from the ‘index finger:ring finger’ ratio to deduce gendered behavioural characteristics of a client… hmmmm???

Concretely, what we do know is that Testosterone levels in early brain development, among many interesting things, can influence laterality, playing a role in handedness and the degree of linguistic lateralisation.  In males, testosterone has many direct effects on the anatomy and metabolism. Male humans are characterised by strong bones, increased muscle mass and a deeper voice (although the aging elderly male voice actually rises in pitch). Testosterone stimulates the growth of the genitals at puberty and is responsible for sperm production throughout adult life. Testosterone, arguably also plays a role in male intelligence–(or lack thereof)! 😛

Testosterone might put hairs on your chest, but it can also contribute to male-pattern baldness and prostate disease. It is a funny little hormone that influences cholesterol metabolism, the production of red blood cells by bone marrow, secondary sex characteristics, musculature, weight, accessory organs, mortality and injury rates. It is sometimes over-popularised for what are actually poorly understood processes, but in recent research, testosterone may be an important factor in understanding plasticity in the brain!!! In this exciting discovery, researchers are beginning to understand a pivotal role testosterone is playing in neurochemical plasticity!

So, the time has come, (as the Walrus said to the Carpenter), to draw your attention to this recent publication which looks at testosterone with respect to environmental influences (the light-dark/sleep-wake cycle) and it’s effects within the brain of a seasonal mammal, the Djungarian hamster (Phodopus sungorus). 
                                             *SIGH* Ah, the beauty! A study of the brain in context!!!
                                                                                                                While many researchers are looking at how to regenerate neurons (which could potentially help stroke victims, paraplegics and alzheimers patients etc), a small group of researchers at the Laboratoire de Neurobiologie des Rythmes, Universite Louis Pasteur, are looking at the role of testosterone in neurochemical plasticity. It is a significant step towards understanding how to guide freshly generated neurons! Regenerating neurons is only part of the journey for accident-recovery patients, guiding these neurons might be tricky and Testosterone may be an important key!  Continue reading “Testosterone and the seasonal regulation of sex-steroids”