Chapter 2 Historical Perspectives

As we will learn, cognitive neuroscience had very humble beginnings back in the time of the Romans, and was essentially dormant for close to two millennia thereafter. A surge of interest in the anatomy, and the brain in particular, overtook scientists in Europe the mid-1800s, pushing the field forward. This time period coincided not only with interest in mapping brain structure to function, but also consideration and description of brain circuits that stand as part of the foundations of cognitive neuroscience today. The need to serve the veterans of the two World Wars, encompassing regions across the planet, led, among other factors, to a worldwide examination of the behavioral consequences of brain damage. Toward the end of the twentieth century and continuing on until today, there has been an explosion of methods that have allowed scientists for the first time to link brain structure and function to mental function in neurologically intact individuals. These methods have provided information at an exquisite level of anatomical and functional detail, and more recent methods drawn from computer science have allowed scientists to ask questions never before possible. As such, there has been and continues to be a stunning worldwide expansion of the field.

ANCIENT TIMES UNTIL THE 1800S

The seeds of the field of cognitive neuroscience were planted more than 2,000 years ago in the time of the Romans. Galen, a physician who ministered to the wounds of the gladiators, noticed that contestants sustaining injury to the arm, leg, or torso retained their powers of thought, whereas those who sustained injury to the head or the brain did not. From these observations, he inferred that the brain was linked to thought, and as such was the first to use patients with circumscribed brain damage to understand mental functions.

Galen's approach was a precursor of the logic we use today to determine which regions of the brain are important for a given mental function. If damage to a particular brain region results in an inability to perform a specific mental function, scientists usually assume that the function must have depended on that brain region. This approach is known as the lesion method. During the history of neuropsychology and cognitive neuroscience, this method has proved immensely powerful in expanding knowledge about the neurological bases of thought and emotion.

INTRODUCTION

In this chapter we discuss the different methods that can be used to understand how the brain influences the way we think, feel, and act. Because cognitive neuroscience is an interdisciplinary field of research, it requires integration of information about the brain with information about behavior. Depending on the question under investigation, we may examine different kinds of information about the brain and behavior. We may want to obtain information about the brain at the neuroanatomical, neurochemical, or neurophysiological level.

At a neuroanatomical level, we may need information about the integrity of brain structures, their connections to other brain regions, and their relationship to particular behavioral patterns. For example, knowing that people have specific difficulties in recognizing faces after sustaining trauma to the ventral regions of the right temporal lobe may allow us to infer a connection between that cognitive process and that brain region. We may also require information about the brain at the neurochemical level. For example, we may want to know how the dysregulation of the neurotransmitter dopamine contributes to the symptoms of schizophrenia. Finally, at the neurophysiological level, we may observe which brain regions are electrically or metabolically active during performance of a specific task. For example, we may want to know the degree to which the right hemisphere is electrically responsive during a musical judgment task.

We can also observe different aspects of behavior. On the one hand, we may want to observe sensory processing in an individual, such as determining whether a person can distinguish high tones from low tones. On the other hand, we may need to examine more central aspects of mental processes, such as the integrity of the memory system. In still other cases, we may want to deconstruct specific mental abilities, such as determining whether a memory deficit is limited to learning new information or extends to retrieving previously learned information as well.

To investigate each of these issues requires particular tools, or research methods. The research methods introduced in this chapter will be referred to throughout this book as we explore the neurocognitive underpinnings of mental activity. During all our discussions, understanding the strengths and limitations of different research methods is important; the adage “You need the right tool for the job” is as apt in cognitive neuroscience as in carpentry.