What term refers to the creation of new neurons in the adult brain?

The term that refers to the creation of new neurons in the adult brain is neurogenesis. This process has been shown to occur primarily in specific regions of the brain, such as the hippocampus, which is involved in memory and learning. Neurogenesis is significant as it demonstrates that the adult brain is capable of some degree of regeneration and adaptation, which contrasts with previous beliefs that neurogenesis only occurred during developmental stages.

Neuroplasticity, while related, refers more broadly to the brain's ability to reorganize itself by forming new neural connections in response to learning or injury. This includes not only the growth of new neurons but also changes in the strength or number of synaptic connections between existing neurons.

Neurotransmission refers to the process by which signaling molecules (neurotransmitters) are released by neurons and transmitted across synapses to communicate with other neurons, which does not involve the creation of new neurons.

Neuromodulation involves the alteration of neuronal signaling properties by neurotransmitters or hormones but does not pertain to the generation of new neurons.

Thus, neurogenesis specifically addresses the formation of new neurons, making it the correct answer.