Affective neuroscience
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.
Brain areas related to emotion
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:Limbic system
- Amygdala – The amygdala is made up of two small, round structures located closer to the forehead to the hippocampi near the temporal poles. The amygdalae are involved in detecting and learning which parts of our surroundings are important and have emotional significance. They are critical for the production of emotion. They are known to be very important for negative emotions, especially fear. Amygdala activation often happens when we see a potential threat. The amygdala uses our past and related memories to help us make decisions about what is currently happening.
- Thalamus – The thalamus is involved in combining sensory and motor signals and then sending that information to the cerebral cortex. The thalamus plays an important role in regulating sleep and wakefulness.
- Hypothalamus – The hypothalamus is involved in producing a physical response with an emotion. The hypothalamus is also used in reward circuits which are associated with positive emotions.
- Hippocampus – The hippocampus is a structure that is mainly involved in memory. It works to make new memories and also connects senses such as visual input, smell or sound to memories. The hippocampus allows long term memories to be stored and retrieves them when necessary.
- Fornix – The fornix is the main connection between the hippocampus to the mammillary bodies. It is important for spatial memory functions, episodic memory and executive functions.
- Mammillary body – Mammillary bodies are important for recollective memory. They are found by the brain stem and cerebrum.
- Olfactory bulb – The olfactory bulbs are the first cranial nerves. They are involved in smell and memory that is connected with specific smells.
- Cingulate gyrus – The cingulate gyrus is located above the corpus callosum. The parts of the cingulate gyrus have different functions, and are involved with affect, visceromotor control, response selection, skeletomotor control, visuospatial processing, and in memory access. The anterior cingulate cortex is important for conscious, subjective emotional awareness as well as motivation. The subgenual cingulate is more active during both experimentally induced sadness and during depressive episodes.
Other brain structures
- Basal ganglia – Basal ganglia are groups of nuclei found on either side of the thalamus. Basal ganglia play an important role in motivation, action selection and reward learning.
- Orbitofrontal cortex – The orbitofrontal cortex is involved in decision making and helping us understand how emotions have influenced our decision making.
- Prefrontal cortex – The prefrontal cortex is the front of the brain, behind the forehead and above the eyes. It plays a role in regulating emotion and behavior by anticipating consequences. The prefrontal cortex also plays an important role in delayed gratification by maintaining emotions over time and organizing behavior toward specific goals.
- * The ventromedial prefrontal cortex is a portion of the prefrontal cortex that has shown to have a significant influence on emotion regulation. Through studies, the vmPFC has shown high activation when presented with highly emotional stimuli. This suggests that this portion of the brain is essential for high emotional arousal.
- Ventral striatum – The ventral striatum is a group of structures thought to play a role in emotion and behavior. An area of the ventral striatum known as the nucleus accumbens is involved in the experience of pleasure. It is common for individuals with addictions to exhibit increased activity in this area when they are exposed to the object of their addiction.
- Insula – This area of the brain plays a significant role in bodily emotions due to its connections to other neural structures that control automatic functions such as heart rate, breathing, and digestion. The insula is also implicated in empathy and awareness of emotion.
- Cerebellum – Cerebellum has many uses. Has a very important role in emotion perception and emotion attributions. Cerebellar dysfunction has been shown to decrease positive emotions during lesion studies. Over the course of evolution, the cerebellum may have evolved into a circuit that helps reduce fear in order to enhance survival. The cerebellum may also play a regulatory role in the neural response to rewarding stimuli, such as money, addictive drugs, and orgasm.
- * A "cerebellar cognitive affective syndrome" has been described resulting in personality change and how the person shows emotions.
- Lateral prefrontal cortex – Using our emotions, the lateral prefrontal cortex is responsible for helping us reach our goals by suppressing harmful behaviors or selecting productive ones.
- Primary sensorimotor cortex – The somatosensory cortex is involved in each stage of emotional processing. We use it to collect information that helps us in identifying and creating emotion, and then regulate that emotion once it has started.
- Temporal cortex – This brain area is important in processing sound, speech, and language use, as well as helping us understand others faces and others emotions based on facial cues. The temporal cortex is responsible for determining the quality and content of our emotional memories.
- Brainstem – The brainstem is composed of three parts: ascending, descending, and modulatory. The brainstem takes information from our environment and creates a bodily response such as crying. The information from the environment and our body's responses to the information we receive is combined in the modulatory part of the brain stem and we are then able to label an emotion.
Right hemisphere
Right hemisphere 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.Valence hypothesis
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.Cognitive neuroscience
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.Cognitive neuroscience tasks in affective neuroscience research
Emotion go/no-go
Emotion go/no-go tasks are used to study behavioral inhibition, especially how it is influenced by emotion. A "go" cue tells the participant to respond rapidly, but a "no-go" cue tells them to withhold a response. Because the "go" cue occurs more frequently, it can be used to measure how well a subject suppresses a response under different emotional conditions.This task is often used in combination with neuroimaging in healthy individuals and patients with affective disorders to identify relevant brain functions associated with emotional regulation. Several studies, including go/no-go studies, suggest that sections of the prefrontal cortex are involved in controlling emotional responses to stimuli during inhibition.