A brief history of human brain mapping

Human functional brain mapping as we presently know it began when the experimental strategies of cognitive psychology were combined with modern brain-imaging techniques (first positron emission tomography and then functional magnetic resonance imaging) to examine how brain function supports mental activities. This marriage of disciplines and techniques galvanized the field of cognitive neuroscience, which has rapidly expanded to include a broad range of the social sciences in addition to basic scientists interested in the neurophysiology, cell biology and genetics of the imaging signals. Although much of this work has transpired over the past couple of decades, its roots can be traced back more than a century.

Introduction

Over the past 30 years the field of cognitive neuroscience has emerged as an important growth area in neuroscience. Cognitive neuroscience combines the experimental strategies of cognitive psychology with various techniques to actually examine how brain function supports mental activities. Leading this research in normal humans are the techniques of functional brain imaging: positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) along with electroencephalography (EEG), electrocorticography (ECoG), magnetoencephalography (MEG) and, most recently, optical imaging with near-infrared spectroscopy (NIRS).

It is easy to conclude that much of the work leading to the emergence of functional brain imaging in particular and cognitive neuroscience in general has transpired over the past decade or so because of much recent prominence at scientific meetings and in the scientific literature. Additionally, it has received substantial media attention probably related to the human fascination with brain-mind questions. In truth, crucial work has been occurring for more than a century.

To place current work in perspective, I present a brief historical overview (Figure 1) of some of the concepts, events and personalities that have shaped functional brain imaging as we know it today. I call upon not only published accounts of many events and discoveries but also recollections shared with me by those who have lived through the remarkable events of the past several decades. Such views serve to not only breathe life into the science but also carry the caveat that they are necessarily colored by one's own involvement.

I focus on human brain imaging with PET and fMRI recognizing that other techniques, particularly electrical (e.g. EEG, MEG and ECoG), also have and will continue to have an important role. I begin with a discussion of the physiology of brain imaging with PET and fMRI.