This chapter is a discussion of methods used to study the nervous system at the level of cells. The introduction defines and describes the microanatomy of neurons and populations of glia and gives an overview of organelles. Next is a discussion of microscopy techniques and images, including light microscopy (bright-field and fluorescence) and electron microscopy. Other techniques which rely on microscopy are then described, including unbiased stereology, fluorescence recovery after photobleaching, and flow cytometry. The chapter concludes with a description of a variety of stains, dyes, and anterograde and retrograde tracers, as well as an interpretation of Sholl analysis figures and dendritic spine quantification.

In this chapter, the insula’s microanatomy, consisting of five main gyri – three anterior short and two posterior long gyri – is described and nomenclature differences from the nineteenth to twenty-first century tabulated to ease communication. The insula’s relationship to neighboring structures is highlighted, as these relationships are important for the exploration of the insula with depth electrodes as part of the presurgical investigation. Quantitative data on the insula’s features (i.e., volumes and extents) are summarized. The chapter finishes with a brief overview of the scarce data on neurotransmitter systems in the insula and the relevance of insular anatomy for the interpretation of functional imaging results with PET.