Cognition I: Mood and Affect Flashcards
Mood
Moods are the conscious perceptions of emotional responses.
Mood and emotion are related and are sometimes mistakenly used interchangeably. There are distinct differences between mood and emotion as highlighted in the table shown on the slide.
Mood
- Longer lasting
- Gradual and continuous
- Weaker
- General (positive and negative)
- Cognitive
Emotion
emotions are unconscious responses that are triggered when the brain detects a specific significant stimulus (Principles of Neural Science) Short term Rapid, Phasic Stronger Specific (sad, happy, angry, surprised) Action orientated
Theories on moods and. Emotions
The James-Lange Theory was the first theory into emotion. It proposes that we experience emotion in responses to bodily changes in our body. Feeling arise when the bodily expression of emotional response enters the consciousness.
Although the James-Lange Theory became popular it came under attack by Walter Cannon proposing emotions can be experiences even if physiology changes cannot be sensed. A new theory was proposed called The Cannon-Bard Theory conducted experiments and found that eliminating sensations did not eliminate emotions proposing that emotional experiences can experienced independent of emotional expression.
The Cannon-Bard Theory focused on emotion centred around the hypothalamus and thalamus. According to the theory, the nature of emotion is determined by the pattern of activation to the thalamus regardless of the physiological responses to the sensory input.
Limbic System: Structures
The Papez circuit was mainly composed of the hippocampus, thalamus and cingulate gyrus.
Papez proposed that there is an emotion system, lying on the medial wall of the brain that links the cortex and the hypothalamus.
Papez believed that the experience of emotion was determined by activity in the cingulate cortex and, less directly, other cortical areas.
Papez expanded the neural circuitry of feeling considerably Beyond the Cannon-Bard theory by interposing a new set of structures between the hypothalamus and and the cerebral cortex.
Not all limbic system structures are in the Papez circuit
Limbic System: Emotive Processing
In the circuit, the cingulate cortex projects emotional experience signals to the hippocampus via the cingulum bundle.
Signals from the hippocampus make connections with the mammillary body of the hypothalamus via the fornix (a bundle of axons).
Papez believed that the hypothalamus governs the behavioural expression of emotion.
Signals from the hypothalamus are sent to sent to the cingulate cortex via a relay in the anterior thalamic nuclei, thus completing the loop.
The loop is arranged so that the hypothalamus and the neocortex can influence each other therefore, linking the experience and expression of emotions.
Papez believed that the cortex is critically involved in the experience of emotion and the activity evoked in other neocortical areas by projections from the cingulate cortex add emotional colouring to the emotional experiences.
Where there is damage to the certain cortical areas, it is also found that there are profound changes in emotional expression, however with little change in perception or intelligence. In addition, tumours located near the cingulate cortex are associated with certain emotional disturbances including fear and depression.
Limbic System: Summary
Although the term limbic system is still used to define a single system for emotion, it has become clear that there is not a single emotion system.
There are an assortment of emotions that is experienced everyday and there are different brain activity associated with each. It is hard to believe that there is only one system as there are structures that are involved in emotion are involved in other functions.
The forebrain structures that process emotional signals participate in a variety of complex brain functions including the interpretation and expression of social behaviour and rational decision- making for example.
In addition, damage to most of the limbic system like the hippocampus does not have effects on the emotional behaviour predicted by the papez circuit, one limbic area- the amygdala was consistently shown to be involved in emotion like fear.
Most structures of the limbic system are involved in other cognitive processes, but it is crucial to emotional processing
Associative learning
Learning the cues that signify reward
Incentive salience
The motivation to seek out the reward, “wanting”
Hedonia
The emotional “hedonic” experience of pleasure after achieving the reward
Dopamine pathways -Functions
Reward ( motivation) Pleasure, euphoria •Motor function (fine tuning) •Compulsion •Perseveration
Serotonin pathways Functions
Mood
•Memory processing •Sleep
•Cognition
Motivation and reward Dopamine
- Ventral tegmental area (VTA) is located in the midbrain
- VTA is the reward “learning centre”
- Dopaminergic cell bodies reside in the VTA
- Projections to the nucleus accumbens
- Mesolimbic pathway
- Projections to the cortex
- Mesocortical pathway
• Tonic firing of dopamine neurons
• Baseline spike activity • Not sufficient to evoke a response in the postsynaptic neuron
Phasic firing of dopamine neurons
- Burst spike activity
* Leads to release of dopamine at the presynaptic neuron and activation of dopamine receptors on postsynaptic neurone
Dopamine firing in the VTA coincides with reward prediction error…
- If reward outcome is correct, no firing occurs as no learning is necessary
- If reward outcome is incorrect, dopamine fires and codes new cues to predict reward
- VTA is involved in learning cues for reward
