Which of the following is not involved in the regulation of sexual behaviour and expression of emotional reactions such as excitement, pleasure, rage and fear?

The hippocampus, amygdala, and hypothalamus are indeed parts of the limbic system, and they work together to regulate emotional responses and behaviors, including those related to sexual behavior. 

Hippocampus: Primarily associated with memory formation and spatial navigation. It plays a role in contextualising emotional experiences.

Amygdala: Involved in the processing of emotions, particularly fear and pleasure responses. It contributes to the emotional aspects of memory formation.

Hypothalamus: Regulates a wide range of physiological functions, including the release of hormones that influence sexual behavior, reproductive functions, and various emotional responses.