Neuroscience
In a book like this, it is impossible to do full justice to a subject as broad and detailed as the branch of science you see at the top of this page. I apologize for what will inevitably be superficial, but I feel I must make the attempt, as some very interesting insights emerge.
Neuroscience is focused on understanding how that part of us we call the brain (or the nervous system to use a more technical term) actually works, and especially in neuropsychology how injury to any part of our brain results in psychological outcomes. It is only in the last generation or two of scientific studies that we have learned as much as we have, and all agree there is a lot more left to learn. Some of the injuries' effects studied happened through strokes and lesions, some through externally caused accidental damage, and some through deliberate experimental interventions such as electrical stimulation or inhibition.
On physical examination of the brain it becomes clear that it is divided into two hemispheres, left and right, by tissue called the corpus callosum. From the data obtained from the sources described above it has become clear that the left and right hemisphere are both physically and functionally asymmetrical. And although they have differing functional strengths and weaknesses, they cooperate (to use a metaphor) to give us the end result of our mental activity. They are connected as well as separated.
Modern thinking about right brain and left brain thinking, although there had been occasional medical insights much earlier, developed from the research in the late 1960s of an American psycho-biologist Roger W Sperry. He discovered that the human brain has two very different ways of thinking. One (the right brain) is visual and processes information in an intuitive and simultaneous way, looking first at the whole picture then the details. The other (the left brain) is verbal and processes information in an analytical and sequential way, looking first at the pieces then putting them together to get the whole. This was the start of what has become a huge debate among scientists, as they rearised that this was an important insight, which needed more study and clarification.
It is only fair to say that though the fundamental premise of asymmetry of the two hemispheres is not challenged, there is still much discussion about the exact differences, and how the two hemispheres interact. The research is definitely unfinished, and if you want to study this in more detail the topic is often referred to as brain lateralization.
As an overview of the conclusions being reached we can say that the strengths of the left brain are: language skills, skilled movement, analytical time sequence processing, exact calculation and fact retrieval. If we reach for something to grasp it, that is seen as left brain activity. The strengths of the right brain are: understanding geometric properties, reading faces, music, understanding of metaphors, expressing emotions, reading emotions, to mention only a few. It is with the right brain that we have empathy with other people or situations.
Neuropsychologists are researching on whether certain psychotic conditions are actually caused by a dysfunction of one of the two hemispheres; for instance, they are asking whether autism or schizophrenia are wholly or partly caused by right brain malfunctioning. To quote a New York Times article: 'Strong evidence suggests that schizophrenia involves decreased communication between the left and right sides of the brain.' Again I am presenting topics and questions for a great deal of further study well beyond the scope of these pages.
In a later section of this book we will come upon two lists: one includes love, joy, peace, kindness, gentleness, and self-control. All very right brain activity. The other list includes strife, jealousy, anger, and selfishness; in other words all grasping features of left brain activity. Look out for the context of these two lists, and you will possibly think along the same lines as I do when you read them.