What areas are mainly responsible for coordinating internal and external responses?

Thalamus and hypothalamus

Explanation:

The anterior region of hypothalamus known as supraotic region secretes several hormones that control both the physical and emotional stress and responses. For instance, CRH hormone triggers the release of cortisol which is an important stress hormone. The posterior region of hypothalamus known as mammillary region controls the memory function.

Thalamus on the other hand is responsible for relaying sensory signals and thus regulates alertness and sleep.

Thus, both Thalamus and hypothalamus are mainly responsible for coordinating internal and external responses