Final answer:
Nicotinic Ach receptors in the ventral tegmental area are ligand-gated ion channels and are essential for neuron activation in brain reward and cognitive functions.
Step-by-step explanation:
The type of nicotinic Ach receptor that dominates in the ventral tegmental area (VTA) is a ligand-gated ion channel which is activated by acetylcholine (ACh) as well as nicotine. These receptors are critical for the depolarization and activation of neurons within the VTA, which is heavily involved in the brain's reward circuit and plays a key role in cognition, affective states, and certain behavioral disorders. Dopaminergic pathways, such as the mesocorticolimbic system, arise from the VTA and are involved in several functions including reward-based learning, locomotion, and various cognitive tasks.