Final answer:
Denise should understand that action potentials only occur at the nodes of Ranvier in myelinated axons, a process known as saltatory conduction, which is faster and more energy-efficient than the continuous conduction in unmyelinated axons.
Step-by-step explanation:
Before beginning her lab rotation with Dr. Hudson, Denise should be well-informed about the nodes of Ranvier and their role in neural conduction. Specifically, action potentials occur only at the nodes of Ranvier in myelinated axons. This is due to the myelination of the axon, where the myelin sheath acts as an insulator for efficient signal transmission. The presence of this myelin covering creates regularly spaced gaps along the axon, known as the nodes of Ranvier. These nodes contain voltage-gated Na+ and K+ channels that are crucial for the regeneration of the action potential.
The propagation method in myelinated axons is known as saltatory conduction, which is a process where the action potential 'jumps' from one node to the next. This method of signal transmission is much faster than the continuous conduction seen in unmyelinated axons. Saltatory conduction also conserves energy by requiring the ion channels to be located only at the nodes, not along the entire length of the axon.
Given this information, the correct option for Denise is b. Action potentials occur only at the nodes of Ranvier in myelinated axons. Knowing this will equip her with foundational knowledge necessary for understanding the research carried out in Dr. Hudson's laboratory.