Within psychology, there is a growing focus on the study of the more pleasant side of human experience. In the past, psychologists - and neuroscientists, too - gave far greater study time to pain, trauma, human loss and suffering in all its guises, but recent developments within the field of positive psychology have shown that happiness, joy and laughter are a more important part of the human experience.
In their new book, Sergio and Vivien Pellis show that play may be an important process in shaping lives that have meaning and are worth living. The Playful Brain is aimed at a wide audience that includes educators and biological and social scientists. Taking such a broad perspective could have meant that the book pleased none of the authors' target audience, but the end result suggests that this is unlikely. Their descriptive and experimental studies on play in many species are inspirational, offering a blueprint on how to do science properly - and good science is never exclusive.
By focusing on play as a valid research domain, the authors draw on their own extensive research in a variety of mammalian species to explore the role that juvenile play exerts on adult behaviour and brain development.
They attempt, via a series of well-presented chapters, to deconstruct the complexity of playfighting using comparisons between species and sexes to build a picture of how playful experience in the juvenile period shapes subsequent adult behaviour, including motor performance, cognitive capacities, emotional stability and social competence.
They also make a good attempt to identify some of the brain mechanisms that are altered by play, although in some cases the information is somewhat limited and some of the assertions are speculative.
This does not detract from the Pellises' fine work - they provide an impetus and direction for future researchers to follow that clearly identifies those structures within the brain that seem the most fruitful to explore.
The most compelling point is their assertion that the amygdala is an important structure for reciprocal playful exchanges, and that its role in learning and modulation in playfighting provides a mechanism for impulse control.
Their interdisciplinary approach leads them to the assertion that playfighting animals are learning how to match their emotional reactions to an unpredictable world via a variety of mechanisms, including impulse control.
The book has breadth and depth in that the presentation of the Pellises' own research and the work of other important players in the field of play research shows that the study of the phenomenon in juvenile animals, including humans, has implications for research in a variety of disciplines.
This gives their book a wider appeal than those interested in simply defining playful exchanges in a number of different species. Playful experience in juveniles may help elucidate the neurobiological underpinnings of impulse-control disorders, including drug abuse, stress and coping - for example, rats reared in social isolation are unable to cope with a variety of novel situations, which in turn leads to stress.
The authors provide an excellent model for neuropsychological research by emphasising that first and foremost behaviour needs to be well defined before we can make any attempt to understand the underlying neurology. Sadly, it is often a clear and full definition of the behaviour under investigation that is so badly neglected in neuroscience research.
Whatever your area of research, The Playful Brain is likely to provide you with findings that will inform your own science, as well as appropriate ways in which to undertake that scientific study.
It is worth noting that the authors conclude by providing a clear link with subcortical reward mechanisms by showing that a variety of species sometimes engage in behaviour purely "for its own sake" - a premise that we should perhaps take to heart in our own research.
The Playful Brain: Venturing to the Limits of Neuroscience
By Sergio and Vivien Pellis
Published 1 April 2009