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 (anterior) 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 (for example, crying) 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 (olfaction) 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. 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.

=== 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 (vmPFC) 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 (sensory information), descending (motor information), and modulatory. The brainstem takes information from our environment (ascending) and creates a bodily response (descending) 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 == 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.

=== 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.

=== Emotional Stroop === Adapted from the Stroop, the emotional Stroop test measures how much attention you pay to emotional stimuli. In this task, participants are instructed to name the ink color of words while ignoring their meanings. Generally, people have trouble detaching their attention from words with an affective meaning compared with neutral words. It has been demonstrated in several studies that naming the color of neutral words results in a quicker response. Selective attention to negative or threatening stimuli, which are often related to psychological disorders, is commonly tested with this task. Different mental disorders have been associated with specific attentional biases. Participants with spider phobia, for example, tend to be more inclined to use spider-related words than negatively charged words. Similar findings have been found for threat words related to other anxiety disorders. Even so, other studies have questioned these conclusions. When the words are matched for emotionality, anxious participants in some studies show the Stroop interference effect for both negative and positive words. In other words, the specificity effects of words for various disorders may be primarily due to their conceptual relation to the disorder's concerns rather than their emotionality.

=== Ekman 60 faces task === The Ekman faces task is used to measure emotion recognition of six basic emotions. Black and white photographs of 10 actors (6 male, 4 female) are presented, with each actor displaying each emotion. Participants are usually asked to respond quickly with the name of the displayed emotion. The task is a common tool to study deficits in emotion regulation in patients with dementia, Parkinson's, and other cognitively degenerative disorders. The task has been used to analyze recognition errors in disorders such as borderline personality disorder, schizophrenia, and bipolar disorder.

=== Dot probe (emotion) === The emotional dot-probe paradigm is a task used to assess selective visual attention to and failure to detach attention from affective stimuli. The paradigm begins with a fixation cross at the center of a screen. An emotional stimulus and a neutral stimulus appear side by side, after which a dot appears behind either the neutral stimulus (incongruent condition) or the affective stimulus (congruent condition). Participants are asked to indicate when they see this dot, and response latency is measured. Dots that appear on the same side of the screen as the image the participant was looking at will be identified more quickly. Thus, it is possible to discern which object the participant was attending to by subtracting the reaction time to respond to congruent versus incongruent trials. The best documented research with the dot probe paradigm involves attention to threat related stimuli, such as fearful faces, in individuals with anxiety disorders. Anxious individuals tend to respond more quickly to congruent trials, which may indicate vigilance to threat and/or failure to detach attention from threatening stimuli. A specificity effect of attention has also been noted, with individuals attending selectively to threats related to their particular disorder. For example, those with social phobia selectively attend to social threats but not physical threats. However, this specificity may be even more nuanced. Participants with obsessive-compulsive disorder symptoms initially show attentional bias to compulsive threat, but this bias is attenuated in later trials due to habituation to the threat stimuli.

=== Fear potentiated startle === Fear-potentiated startle (FPS) has been utilized as a psychophysiological index of fear reaction in both animals and humans. FPS is most often assessed through the magnitude of the eyeblink startle reflex, which can be measured by electromyography. This eyeblink reflex is an automatic defensive reaction to an abrupt elicitor, making it an objective indicator of fear. Typical FPS paradigms involve bursts of noise or abrupt flashes of light transmitted while an individual attends to a set of stimuli. Startle reflexes have been shown to be modulated by emotion. For example, healthy participants tend to show enhanced startle responses while viewing negatively valenced images and attenuated startle while viewing positively valenced images, as compared with neutral images. The startle response to a particular stimulus is greater under conditions of threat. A common example given to indicate this phenomenon is that one's startle response to a flash of light will be greater when walking in a dangerous neighborhood at night than it would under safer conditions. In laboratory studies, the threat of receiving shock is enough to potentiate startle, even without any actual shock. Fear potentiated startle paradigms are often used to study fear learning and extinction in individuals with post-traumatic stress disorder (PTSD) and other anxiety disorders. In fear conditioning studies, an initially neutral stimulus is repeatedly paired with an aversive one, borrowing from classical conditioning. FPS studies have demonstrated that PTSD patients have enhanced startle responses during both danger cues and neutral/safety cues as compared with healthy participants.

== Learning == Affect plays many roles during learning. Deep, emotional attachment to a subject area allows a deeper understanding of the material and therefore, learning occurs and lasts. The emotions evoked when reading in comparison to the emotions portrayed in the content affects comprehension. Someone who is feeling sad understands a sad passage better than someone feeling happy. Therefore, a student's emotion plays an important role during the learning process. Emotion can be embodied or perceived from words read on a page or in a facial expression. Neuroimaging studies using fMRI have demonstrated that the same area of the brain that is activated when feeling disgust is activated when observing another's disgust. In a traditional learning environment, the teacher's facial expression can play a critical role in language acquisition. Showing a fearful facial expression when reading passages that contain fearful tones facilitates students learning of the meaning of certain vocabulary words and comprehension of the passage.

== Models == The neurobiological basis of emotion is still disputed. The existence of basic emotions and their defining attributes represents a long lasting and yet unsettled issue in psychology. The available research suggests that the neurobiological existence of basic emotions is still tenable and heuristically seminal, pending some reformulation.

=== Basic emotions ===

These approaches hypothesize that emotion categories (including happiness, sadness, fear, anger, and disgust) are biologically basic. In this view, emotions are inherited, biologically based modules that cannot be separated into more basic psychological components. Models following this approach hypothesize that all mental states belonging to a single emotional category can be consistently and specifically localized to either a single brain region or a defined network of brain regions. Each basic emotion category also shares other universal characteristics: distinct facial behavior, physiology, subjective experience and accompanying thoughts and memories.

=== Psychological constructionist approaches === This approach to emotion hypothesizes that emotions like happiness, sadness, fear, anger and disgust (and many others) are constructed mental states that occur when brain systems work together. In this view, networks of brain regions underlie psychological operations (e.g., language, attention, etc.) that interact to produce emotion, perception, and cognition. One psychological operation critical for emotion is the network of brain regions that underlie valence (feeling pleasant/unpleasant) and arousal (feeling activated and energized). Emotions emerge when neural systems underlying different psychological operations interact (not just those involved in valence and arousal), producing distributed patterns of activation across the brain. Because emotions emerge from more basic components, heterogeneity affects each emotion category; for example, a person can experience many different kinds of fear, which feel differently, and which correspond to different neural patterns in the brain.

== Aging == People typically associate aging with a decline in the functioning of all mental processing abilities; however, this is not the case for emotion regulation. Older adults typically have a stronger drive to maintain and improve on their emotional well being. Thus providing them to utilize emotion regulation skills that provide a higher satisfaction in life.

=== Role of the vmPFC in emotion regulation of older adults === The ventromedial prefrontal cortex (vmPFC) has a significant influence on emotion regulation, especially regarding high emotional arousing stimuli. Compared to other areas of the prefrontal cortex (PFC), the vmPFC loses volume at a much lower rate. Due to this, an older person's emotional regulation abilities are not heavily impacted by brain changes associated with aging. Additionally, the anterior cingulate cortex (ACC) is an important area of the brain that is used for emotion regulation. The ACC has proven to be a key player in emotion regulation in not just young adults, but also ...

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Neuroscience - Neuroscience