A crowd watches a tightrope walker. The specific movements and perilous position of the acrobat are thought to resonate with viewers by engaging their system of mirror neurons. These neurons are activated both when an individual performs a set of movements, and when he or she observes those same movements performed by others. Similar neural systems may underlie social cognition as well, allowing us to perceive and comprehend the mental states of others. (Reproduced, with permission, from Arthur Paxton.)
So far in this book we have examined the properties of individual nerve cells and how they communicate at synapses to produce simple reflex behaviors. We now begin to consider larger, interconnected networks of neurons, the complex circuits that give rise to mental activity: perception, planned action, and thought. The field of systems neuroscience aims to understand how these networks produce the cognitive functions of the brain, one of the ultimate challenges of science. We need to know how sensory information is perceived, and how perceptions are assembled into inner representations and recruited into plans for immediate behavior or concepts for future actions. It is still unclear how complex memories are made and how percepts, ideas, and feelings are transformed into language.
Neural science first emerged in the mid-1950s with the development of powerful techniques for exploring the cellular dynamics of the nervous system and with the convergence into a single discipline of several previously separate disciplines concerned with the brain and behavior: molecular biology, neuroanatomy, electrophysiology, and cell and developmental biology. The modern science of mind is the pragmatic result of the attempt to merge neural science with cognitive psychology. New techniques permit us to observe the system properties of the brain directly, not only in animal models, but in controlled behavioral experiments in alert, behaving people. As a result neural science is able to address testable hypotheses about how brain functions lead to mental processes such as perception, memory, decisions, and actions.
The aim of the new science of mind is to examine classical philosophical and psychological questions about mental functions in the light of modern cell and molecular biology. This is a bold undertaking. How do we begin to think about perception, ideas, action, and feelings in biological terms? So far, progress in understanding the major functional systems of the brain—the sensory, motor, motivational, memory, and attentional systems—has benefited from a reductionist approach to mental function. This approach is based on the assumption that these functions will emerge from the biological properties of nerve cells and of their pattern of interconnections. According to this view, which was introduced in Chapter 1, brain and mind are inseparable. Mind can be considered a set of operations carried out by the brain, an information-processing organ made powerful by the enormous number, variety, and interactions of its nerve cells and by the complexity of interconnection among these cells. In this ...