Final answer:
The neurotransmitter acetylcholine impacts motor functions by associating sensory stimuli with learned behavior and coordinating complex movements, primarily moderated by the frontal lobe.
Step-by-step explanation:
The ACh-dependent alteration of motor cortex and auditory topographic representations involves the neurotransmitter acetylcholine affecting motor functions and sensory processing, specifically associating sensory stimuli with learned behavior and coordinating complex movements. Acetylcholine operates in the brain as a neurotransmitter and as a neuromodulator, playing a key role in various functions like arousal, attention, and memory. When it comes to sensory processing, the cerebral cortex handles the initial perception which progresses to associative and integrative processing in multimodal areas, leading to responses which then initiate motor processing in different cortical areas, particularly controlled by the frontal lobe.