Affective neuroscience is the study of how the brain processes emotions. This field combines neuroscience with the psychological study of personality, emotion, and mood. The basis of emotions and what emotions are remains an issue of debate within the field of affective neuroscience.

The term "affective neuroscience" was coined by neuroscientist Jaak Panksepp in the early 1990s, at a time when cognitive neuroscience focused on parts of psychology that did not include emotion, such as attention or memory.

Emotions are thought to be related to activity in brain areas that direct our attention, motivate our behavior, and help us make decisions about our environment. Early stages of research on emotions and the brain was conducted by Paul Broca, James Papez, and Paul D. MacLean. Their work suggests that emotion is related to a group of structures in the center of the brain called the limbic system. The limbic system is made up of the following brain structures:

Research has shown the limbic system is directly related to emotion, but there are other brain areas and structures that are important for producing and processing emotion.

Many theories about the role of the right hemisphere in emotion has resulted in several models of emotional functioning. After observing decreased emotional processing after right hemisphere injuries, C.K. Mills hypothesized emotions are directly related to the right hemisphere. In 1992, researchers found that emotional expression and understanding may be controlled by smaller brain structures in the right hemisphere. These findings were the basis for the right hemisphere hypothesis and the valence hypothesis.

It is believed that the right hemisphere is more specialized in processing emotions than the left hemisphere. The right hemisphere is associated with nonverbal, synthetic, integrative, holistic and gestaltic mental strategies. As demonstrated by patients who have increased spatial neglect when damage affects the right brain rather than the left brain, the right hemisphere is more connected to subcortical systems of autonomic arousal and attention. Right hemisphere disorders have been associated with abnormal patterns of autonomic nervous system responses. These findings suggest the right hemisphere and subcortical brain areas are closely related.

According to the valence hypothesis, although the right hemisphere is involved in emotion, it is primarily involved in the processing of negative emotions, while the left hemisphere is involved in processing positive emotions. In one explanation, negative emotions are processed by the right brain, while positive emotions are processed by the left. An alternative explanation is that the right hemisphere is dominant when it comes to feeling both positive and negative emotions. Recent studies indicate that the frontal lobes of both hemispheres play an active role in emotions, while the parietal and temporal lobes process them. Depression has been associated with decreased right parietal lobe activity, while anxiety has been associated with increased right parietal lobe activity. Based on the original valence model, increasingly complex models have been developed as a result of the increasing understanding of the different hemispheres.

While emotions are integral to thought processes, cognition has been investigated without emotion until the late 1990s, focusing instead on non-emotional processes such as memory, attention, perception, problem solving, and mental imagery. Cognitive neuroscience and affective neuroscience have emerged as separate fields for studying the neural basis of non-emotional and emotional processes. Despite the fact that fields are classified according to how the brain processes cognition and emotion, the neural and mental mechanisms behind emotional and non-emotional processes often overlap.