What Do the Mushroom Bodies Do for the Insect Brain? An Introduction

Despite public claims to the contrary, our functional understanding of the brain is still rudimentary. Starting with F.J. Gall’s Phrenology of the late eighteenth century, one of the major drives has been to assign functions to discrete regions of the brain. In humans and other primates, lesions and noninvasive imaging techniques have provided fascinating insights into the underlying functional topology of the brain. However, lesions in humans relate brain areas comprising millions of neurons to clinical tests, interrogation, and life histories. Similarly, functional imaging usually ties regions of increased blood flow to mental activity conveyed by verbal or visual instructions. The striking specificity of behavioral and mental deficits after local brain damage is difficult to reconcile with the high degree of integration in the neural circuitry. The situation is as perplexing as that met in brain stimulation experiments in which gross perturbations of sophisticated neural activity patterns in the brain …