Chapter 3: Analysis of Dendritic Arborization and Spine Morphology

Neurons are specialized computational compartments that integrate and regulate the propagation of information. The principle language used by neurons to communicate with each other is the action potential. Numerous biophysical and structural properties of neurons have evolved to modulate action potential integration and propagation. Cellular morphology is crucial to our understanding of information processing and communication styles, because neuronal shape is directly related to the computations performed by the cell [1]. Two key morphological characteristics of neurons are dendritic arbor structure and dendritic spine geometry. While spines [2] and dendritic branches [3] can both operate as computational compartments, how their shape, size, and structure affect their function and intrinsic properties is still poorly understood. An astonishing diversity of dendritic arbor structures exists among neurons of different and similar classes (Fig 3.1). The shape, size, and complexity of dendritic trees can modulate action potential propagation [4] and influence the intrinsic firing pattern of a neuron [5]. Specifically, Mainen and Sejnowski demonstrated that firing patterns correlate strongly with the extent of arborization, and Vetter et al. [4] showed that action potential propagation is strongly influenced by 1) the number of branching points, 2) the rate of increase in dendritic membrane area, and 3) the relationship between the diameter of parent and daughter dendrites at branchpoints. Ultimately, both of these studies imply