Final answer:
The ascending pathways in the tegmentum are the mesostriatal and mesolimbic pathways, which originate from dopaminergic neurons in the substantia nigra and VTA, respectively, and are essential for motor activity and reward-based behaviors.
Step-by-step explanation:
Ascending pathways in the tegmentum include the mesostriatal and mesolimbic pathways. The tegmentum, located in the brain stem, is a region enriched with nuclei that regulate vital functions and serve as a conduit for information processed by the cranial nerves. Specifically, the mesostriatal pathway, originating largely from dopaminergic neurons in the ventral sheet of the substantia nigra pars compacta (SNc), plays a critical role in controlling motor activities, reward-based learning, and sequencing. On the other hand, the mesolimbic pathway arises predominantly from the dorsal sheet of the SNc and dorsal ventral tegmental area (VTA), innervating areas such as the amygdala and the nucleus accumbens, implicating it in limbic-motor integration and behaviors related to reward and addiction.