The striatum is associated with which of the following functions?

The striatum is primarily involved in the coordination and regulation of complex motor actions. It plays a crucial role in several motor control processes, including the initiation and execution of movements, as well as skills and habits formed through practice. This region is integral to coordinating the fine-tuning of voluntary motor activity and is a core component of the basal ganglia, which helps facilitate smooth and balanced movement. As a result, damage or dysfunction in the striatum is often associated with motor disorders, such as Parkinson's disease and Huntington's disease, further underlining its significance in motor function.

While the striatum does have indirect roles in other functions, such as emotional processing and aspects of cognition, its most direct and well-established function remains related to complex motor actions. Thus, the association with motor functions is what makes the first choice the correct answer in this context.