What is Affective Neuroscience? Explained
Contents
- Introduction
- Brain areas
- Cognitive neuroscience
- Cognitive neuroscience tasks in affective neuroscience research
- Learning
- Models
Introduction
The study of the brain mechanisms of emotion is known as affective neuroscience. Neuroscience is combined with the psychological study of personality, emotion, and mood in this interdisciplinary field. The presence of 'fundamental emotions' and their distinguishing characteristics is a long-standing and unresolved topic in the discipline.
Neuroscientist Jaak Panksepp developed the phrase at a time when cognitive neuroscience was focused on non-emotional cognition, such as attention and memory.
Brain areas
Emotions are assumed to be linked to activity in brain areas that direct our attention, motivate our conduct, and determine the significance of what we see. Emotion is linked to a group of structures in the centre of the brain termed the limbic system, which includes the hypothalamus, cingulate cortex, hippocampi, and other structures, according to pioneering studies by Paul Broca (1878), James Papez (1937), and Paul D. MacLean (1952). Although limbic structures have been linked to emotion, other structures have been discovered to have greater emotional significance. The following brain structures are thought to be involved in emotion at the moment.
Limbic system
- Amygdala - The amygdalae are two tiny, spherical structures at the temporal poles that are located anterior to the hippocampi. The amygdalae are responsible for sensing and learning which aspects of our environment are essential and emotional. They're important for the formation of emotion, and they're especially important for unpleasant emotions like fear. Multiple studies have demonstrated that when the amygdala detects a potential threat, it activates multiple circuits that allow the amygdala to use associated past memories to better appraise the threat.
- Thalamus - The thalamus is responsible for transferring sensory and motor impulses, particularly visual inputs, to the cerebral cortex. The thalamus is a brain structure that regulates sleep and waking.
- Hypothalamus - The hypothalamus is engaged in reward circuits as well as providing a physical output associated with an emotion.
- Hippocampus - The hippocampus is a memory-related structure found in the medial temporal lobes. It works to create new memories and connects sensory input such as sight, smell, and sound to memories. The hippocampus stores long-term memories and retrieves them when they are needed. The amygdala uses memories to help it analyse stimuli.
- Fornix - The fornix connects the hippocampus to the mammillary bodies and is the main output channel. It has been discovered to be a key region in the control of spatial memory, episodic memory, and executive processes.
- Mammillary bodies - Mammillary bodies play a vital role in recollective memory.
- The olfactory bulbs, which are located on the ventral side of the frontal lobe, are the first cranial nerves. They play a role in olfaction, or the ability to detect odours.
- Cingulate gyrus - The cingulate gyrus is a portion of the limbic system that is located above the corpus callosum. The cingulate gyrus is involved in affect, visceromotor control, response selection, skeletomotor control, visuospatial processing, and memory access, among other things. The anterior cingulate cortex, which is a component of the cingulate gyrus, is assumed to play a key role in attention and behaviorally demanding cognitive activities. It could be especially crucial when it comes to conscious, subjective emotional awareness. This part of the brain may be involved in the initiation of motivated behaviour. During both experimentally generated melancholy and depressive episodes, the subgenual cingulate is more active.
Other brain structures
- Basal ganglia - On either side of the thalamus, there are groupings of nuclei called basal ganglia. Motivation, action selection, and reward learning are all influenced by the basal ganglia.
- Orbitofrontal cortex – The orbitofrontal cortex is a key structure in decision-making and emotion's influence on that decision.
- Prefrontal cortex - The front of the brain, behind the forehead and above the eyes, is known as the prefrontal cortex. By anticipating outcomes, it appears to play a vital role in the regulation of mood and behaviour. It may play a key role in delayed gratification by regulating emotions throughout time and directing behaviour toward certain objectives.
- ventral striatum - The ventral striatum is a collection of subcortical structures that are hypothesised to play a function in emotion and behaviour. The nucleus accumbens, a component of the ventral striatum, is hypothesised to be involved in pleasure perception. When people with addictions come into contact with the object of their addiction, their activity in this region increases.
- Insula - Because it is related to other brain regions that regulate the body's autonomic functions, the insular cortex is assumed to play a vital role in the bodily experience of emotion (heart rate, breathing, digestion, etc.). The insula is involved in empathy and emotional awareness.
- Cerebellum - Researchers have identified a "Cerebellar Cognitive Affective Syndrome." The cerebellum has an important role in emotional regulation, according to both neuroimaging studies and investigations following pathological cerebellar injuries (such as a stroke). Cerebellar dysfunction has been shown in lesion studies to reduce the sensation of happy emotions. While the responses to terrifying stimuli were not reduced in these tests, the stimuli did not recruit regions that would typically be activated (such as the amygdala). Alternative areas, such as the ventromedial prefrontal cortex, the anterior cingulate gyrus, and the insula, were stimulated instead. This could indicate that the cerebellum evolved as a redundant fear-mediating circuit to aid survival under evolutionary pressure. It could also point to the cerebellum's participation in the neuronal response to rewarding stimuli like money, drugs of abuse, and orgasm.
- Lateral prefrontal cortex
- Primary sensorimotor cortex
- Temporal cortex
- Brainstem
Right hemisphere
It has been hypothesised that the right hemisphere is directly involved in emotion processing. Several models of emotional functioning have emerged as a result of scientific thought on its role. After observing impaired emotion processing in individuals with right hemisphere injuries, C. K. Mills was one of the first researchers to propose a direct relationship between the right hemisphere and emotion processing. Neocortical structures were discovered to be involved in emotion in the late 1980s and early 1990s. The right hemisphere hypothesis and the valence hypothesis were developed as a result of these observations.
Right hemisphere hypothesis
According to the right hemisphere hypothesis, the right hemisphere is specialised for emotion expression and perception. It's been connected to nonverbal, synthetic, integrative, holistic, and gestaltic mental techniques. When injury affects the right brain vs the left brain, the right hemisphere is more in touch with subcortical systems of autonomic arousal and attention, as shown in individuals with higher spatial neglect. Abnormal patterns of autonomic nerve system responses have been associated to right hemisphere diseases. These findings point to a substantial link between the right hemisphere and the subcortical brain areas.
Valence hypothesis
The valence theory accepts the right hemisphere's function in emotion, but claims that it is primarily concerned with the processing of negative emotions, whilst the left hemisphere is concerned with the processing of good emotions. Much has been said and written about the two hemispheres. According to one theory, negative emotion is processed by the right hemisphere whereas positive emotion is processed by the left. According to a second version, the right hemisphere is more dominant in both positive and negative feeling. The frontal lobe of both hemispheres is involved in emotions, while the parietal and temporal lobes are involved in emotion processing, according to current study. Depression has been linked to a decrease in right parietal lobe activity. as well as heightened activity in the right parietal lobe Increased right parietal brain activity has been linked to anxiety arousal and decreased right parietal lobe activity has been linked to depression . With a better understanding of the distinct hemispheres, more intricate models have emerged, all based on the basic valence model.
Cognitive neuroscience
Cognitive neuroscience tasks in affective neuroscience research
Emotion go/no-go
The emotion go/no-go task has been used to investigate behavioural inhibition, specifically its emotional modulation. This task, which is based on the original go/no-go paradigm, combines affective "go cues," in which the participant must produce a physical reaction quickly, and affective "no-go cues," in which the person must withhold a response. The activity assesses a subject's capacity to suppress a response under various emotional situations since "go cues" are more common.
The task is commonly used in emotional regulation tests, and it's frequently used in conjunction with neuroimaging measures to pinpoint relevant brain function in both healthy people and people with affective disorders.
Go/no-go studies, for example, converge with other methodologies to implicate prefrontal cortical areas during suppression of emotionally valenced inputs.
Emotional Stroop
An variation of the original Stroop task, the emotional Stroop task, examines attentional bias to emotional stimuli. Participants must name the ink colour of the words provided while ignoring the meanings of the words. Participants have a harder time separating attention from affectively valenced words than neutral terms in general. The response latency in naming the hue of neutral words versus emotional words is used to measure this interference from valenced words.
This task is frequently used to assess selective attention to scary and other negatively valenced stimuli, most frequently in the context of psychopathology. A variety of mental diseases have been reported to have disorder-specific attentional biases. Participants with spider phobia, for example, have a bias toward spider-related terms but not other negatively valenced phrases. Threat words have been linked to other anxiety disorders, according to similar research. Other studies, however, have cast doubt on these conclusions. When the words are matched for emotionality, anxious participants in certain studies show the Stroop interference effect for both negative and positive phrases. This suggests that the specificity effects for distinct conditions may be mostly due to the semantic relationship between the words and the disorder's concerns, rather than the words themselves.
Ekman 60 faces task
The Ekman faces task is designed to assess how well people recognise six fundamental emotions. Ten black-and-white images of actors (6 male, 4 female) are shown, each exhibiting a different emotion. Participants are frequently asked to name the displayed emotion as rapidly as possible. The task is frequently used to investigate emotion regulation problems in people with dementia, Parkinson's disease, and other cognitively degenerative diseases. Recognition errors in diseases like borderline personality disorder, schizophrenia, and bipolar disorder have all been studied using this task.
Dot probe (emotion
The emotional dot-probe paradigm is a task that measures selective visual attention to affective stimuli and the failure to disengage attention from them. A fixation cross is placed in the centre of the screen to start the paradigm. A dot appears behind either the neutral stimulus (incongruent condition) or the affective stimulus after an emotional stimulus and a neutral stimulus appear side by side (congruent condition). Response latency is tested by asking participants to indicate when they notice this dot. Dots that appear on the same side of the screen as the image the participant was viewing will be recognised faster. By subtracting the reaction time to respond to congruent versus incongruent stimuli, it is feasible to determine which object the person was focused on.
Individuals with anxiety disorders pay attention to threat-related cues, such as frightening faces, in the best-documented studies using the dot probe paradigm. Anxious people react faster to congruent trials, which could reflect heightened attentiveness to threats and/or a failure to dissociate attention from hazardous stimuli. Individuals attending selectively to risks linked to their disorder have been observed to have a specificity impact of attention. People with social phobia, for example, pay attention to social hazards but not to physical threats. This specificity, though, could be considerably more nuanced. Participants with obsessive-compulsive disorder symptoms initially display attentional bias to compulsive threat, but due to habituation to the threat stimuli, this bias is decreased in later trials.
Fear potentiated startle
In both animals and humans, fear-potentiated startle (FPS) has been used as a psychophysiological indicator of fear reaction.The magnitude of the eyeblink startle reflex, which may be evaluated by electromyography, is the most common way to estimate FPS. This eyeblink reflex is an objective sign of anxiety since it is an innate protective reaction to an abrupt elicitor. Bursts of noise or rapid flashes of light are commonly used in FPS paradigms when an individual is paying attention to a collection of stimuli. Emotion has been found to influence startle responses. While compared to neutral images, healthy people have increased startle reactions when seeing negatively valenced images and decreased startle responses when viewing positively valenced images.
Under threat, the startle reaction to a particular stimuli is enhanced. A popular example given to demonstrate this effect is that one's startle response to a flash of light is larger when strolling in a risky neighbourhood late at night than when walking in safer surroundings. Even without any real shock, the threat of receiving a shock was enough to enhance startle in laboratory tests.
Fear learning and extinction in people with post-traumatic stress disorder (PTSD) and other anxiety disorders are frequently studied using fear potentiated startle paradigms. In fear training experiments, a neutral stimulus is repeatedly paired with an aversive stimulus, as in classical conditioning. When compared to healthy participants, PTSD patients show increased startle responses under both threat and neutral/safety cues, according to FPS research.
Learning
During the learning process, affect plays a variety of roles. Learning occurs and lasts when a person has a strong emotional attachment to a subject area. This enables for a deeper knowledge of the information and, as a result, learning occurs and lasts. Comprehension is influenced by the emotions felt when reading in relation to the emotions depicted in the text. Someone who is sad has a better understanding of a sad passage than someone who is pleased. As a result, a student's emotional state is crucial during the learning process.
Words read on a page or a facial expression can embody or perceived as emotion. The same part of the brain that is activated when feeling disgust is activated when viewing another's disgust, according to neuroimaging research employing fMRI. In a traditional learning setting, the teacher's facial expression can have a significant impact on language learning. When reading texts with terrifying tones, students can acquire the meaning of key vocabulary items and gain a better understanding of the passage by using a fearful facial expression.
Models
Emotion's neurological origin is still debated. The presence of basic emotions and their distinguishing characteristics is a long-standing and unresolved psychological question. Based on the present evidence, the neurobiological presence of basic emotions is still plausible and heuristically seminal, pending reformulation.
Basic Emotions
Psychological constructionist approaches
Happiness, sorrow, fear, rage, and contempt (among other emotions) are thought to be created mental states that emerge when brain systems interact together, according to this theory. According to this theory, psychological activities (such as language, attention, and so on) are underpinned by networks of brain regions that interact to produce emotion, perception, and cognition. The network of brain regions that underpin valence (pleasant/unpleasant feelings) and arousal is one psychological operation necessary for emotion (feeling activated and energized).
Emotions are formed when neural systems supporting several psychological activities (not simply valence and arousal) interact, resulting in dispersed patterns of activation across the brain. Because emotions are made up of more fundamental components, heterogeneity affects each emotion category. For example, a person can have many different varieties of dread, each of which feels different and corresponds to different neural patterns in the brain.
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