The brain and the mind are two sides of the same coin. We have always wanted to understand how our minds work but, until recently, lacked the tools to investigate the brain.
The brain is the most complicated object in the known universe. Its 100 billion nerve cells (nearly 20 times the number of people on earth) are each connected to thousands of other nerve cells in a bewilderingly complex network.
Enormous strides have been made in understanding the chemical and electrical processes that nerve cells use to communicate with each other, but much remains to be discovered.
One of the greatest mysteries is the process by which this network generates awareness, perception, behaviour and emotions, and how it does this at the same time as processing sensory input and controlling muscles and all other organs.
I decided to work in neuroscience in 1980 because of my interest in the causes of high blood pressure.
Although hormones produced by the kidney, the adrenal gland and other sites can all modulate blood pressure, it was becoming increasingly clear that the brain was enormously important.
We began mapping sites in the brain where particular hormones might act to modulate body fluid and salt balance, and blood pressure. The results pointed to new ways hormones and neurotransmitters could act in - and on - the brain.
Soon, my interest went into the fascinating area of how the brain uses chemical transmitters.
When I started working in medicine in 1960, there was no way to image the structure of the living brain.
All this changed with the invention of the CT scanner in 1967 and the MRI scanner in 1973. MRI now routinely provides exquisitely detailed structural images, as well as images of brain function.
Neuroscience has become one of the most exciting and active areas of science. It encompasses medicine, psychology and psychiatry, has strong links with biology, biochemistry, endocrinology and rests on behavioural physiology, chemistry, physics, and mathematics.
The brain's actions underlie our thoughts, emotions, and beliefs. The explanations we create, and the way we process information, have a huge effect on our moods and behaviour.
We are beginning to understand how abnormalities in transmission at synapses can cause diseases ranging from autism to schizophrenia, how transmitter chemicals can affect mood, anxiety and even love and commitment.
Understanding the enormously complicated brain network seemed an impossible task; each pathway seemed to use its own specific combination of chemical transmitters.
But by combining genomics and optics, it is now possible to monitor and modulate the activity of pathways in the living brain.
We used to believe the brain's network of intricate connections was fixed after early childhood. But we now know the brain is highly plastic or changeable, and able to modify its structure and function in response to learning and memory.
Recovery from injury and response to disease depend to a large degree on this neural plasticity. Plasticity is most active in early childhood although it persists throughout life. In young children, environmental influences can have profound and long-lasting effects on brain development. These effects can be negative when they face malnutrition, or deprivation of love and attention, mental and physical stimulation. Conversely, the provision of these needs, and a rich cultural and intellectual environment can contribute to optimal development.
In parallel with these understandings in neuroscience at the cellular and network levels, there have been important discoveries about the mind. One of these is the development of cognitive behaviour therapy, which can alleviate anxiety and depression.
We are in the midst of a flourishing of neuroscience. We can look forward to enormous advances in understanding how the normal brain works and how it malfunctions in brain disorders.
This will lead to radically new, more effective treatments and, ultimately, the prevention of brain disorders that plague our society.
• Fred Mendelsohn is an emeritus professor at the University of Melbourne and co-curator of the Melbourne Festival of Ideas' programme on brains and minds.