The answer to this question is complex and requires a distinction between different levels of human existence:

Animals and Their Nature

Animals have basic emotions such as joy, fear, anger, and sadness.

In the Divine Principle, it is explained that although animals possess an "inner nature," they do not have a "spiritual self" like humans. They can perform simple thought processes and have memory, but do not have a soul and a spiritual self like humans. 

We can therefore assume that all basic emotions and thought processes can be generated in the body and brain without the need for a spiritual self and a spiritual mind. 

The Human Brain 

The human brain is the most highly developed brain in the animal kingdom. 

We can therefore expect that it is capable of carrying out more complex thought processes and producing more differentiated emotions than the brain of an animal.

Despite its capabilities, however, the human brain remains a physical organ and thus part of the physical body.

It is not identical with the "spiritual self." The brain processes information and thus fulfills a physical function, while the spirit represents a deeper, immaterial dimension of being.