Psychobiology of emotion Flashcards
What are emotions
Emotions are transient events, produced in response to external or internal events of significance to the individual, characterised by attention to the evoking stimulus and changes in physiological arousal, motor behaviour and feelings and endanger a biasing of behaviour.
Emotion triad
Physiological responses
a readiness to act in specific ways and
feelings
Relevance of emotions to psychiatric disorders
Almost all psychiatric disorders involve emotional disturbance
- affective disorder
- personality disorder
- psychosis eg schizophrenia
- autism
- forensic psychiatry ie psychopathy, violence
- addiction- cues, craving and pleasure
Relevance of emotions to medicine
Visiting a doctor/hospital evokes powerful emotions (fear, sadness, anger, surprise, disgust, happiness)
Emotions can profoundly influence treatment compliance:
- fear: delay presentation/treatment compliance
- disgust: disease avoidance and stigma
- anger: engagement with the clinical team
- sadness: poorer outcomes (diabetes, heart attack, surgery)
Plutchiks theory
There are 8 basic emotions arranged in pairs of opposites ie joy and sadness trust and disgust fear and anger surprise and anticipation
Frijdas theory
Classification of emotions based on predisposition to specific actions eg approach/avoidance etc
James Lange Theory
Perceiving frightening situation–> run away or freeze and heart sweating dry mouth etc–> FEEL fear
Cannon Bard theory
percieve frightening situation–> feel fear–> heart, sweatingand dry mouth ect which also facilitates run away or freeze
Schachter and singer theory
2 factor theory of emotion: cognitive interpretation of physiological response
Suproxin experiment–> actually given either adrenaline or placebo–> informed, misinformed or ignorant –> then either exposed to euphoria condition or anger condition
Clinical relevance of S and S theory: Panic disorder
Bodily sensations are wrongly appraised as evidence of impending catastrophic illness
Interpretations of whats happening induce anxiety which exacerbates the physiological effects, which leads to false interpretation which… ie positive feedback
Patients with panic disorder attend to cues suggestive of sudden severe illness more readily than neutral cues. unlike normals or other types of anxious patient
Learning from the visual system
Dorsal stream–> where
Ventral stream–> what
Evolution of the limbis system concept
Reverberating circuit supporting emotion
Motivation, emotion, memory, bias
Originally: cingulate, hippocampus,, amygdala and septal region
Expanded to include:
1) Prefrontal cortex (dense interconnections)
2) Hypothalamus- peripheral interace , viscero-endocrine effector, homeostasis
3) Paralimbic cortices eg insula
4) Ventral striatum (NuAcc and mesolimbic dopaminergic system)- reward and motivation
Convergence in limbic system
external sensory state sensed by sensory processing sent to cortex
Internal sensory state sense by interoceptive (incl visceral, hormonal and autonomic) stimuli sent to the hypothalamus
Hippocampus
Memory
- encoding and recall
- long term storage
- episodic, declaratice
- not procedural/implicit
Other parts of memory circuit
- anterior thalamus, mamillary bodies, fornx
- amnestic syndromes eg korsakoffs psychosis
Spatial processing and navigation
- place cells in rats
- taxi drivers
- context
The amygdala
Complex collection of nuclei located in the medial temporal lobe, dividable into two basic areas (these areas receive extensive inputs from sensory areas of cortex):
- Corticomedial (nuclei project directly to hypothalamus)
- Basolateral (nuclei have more extensive and diffuse sets of projections including frontal cortex)
Function:
- extensive evidence that amygdala is involved in emotional processing including recognition of emotions in others and emotional learning. Clinical obervations eg loss of normal emotional responses after amygdala damage
Amygdala and fear conditioning
Conditioning a tone to a shock results in the tone coming to elicit fear reactions.
Prior to conditioning, the amygdala does not fire in response to tones
After conditioning it responds to tones paired with shock, but not to tones unpaired with shock
Heart rate increases in response to the tone are abolished by amygdala lesions
Amygdala: Emotional memory
Level of amygdala activity during encoding of an emotional image predicts whether you subsequently remember it (not true for non-emotional images)
Benzodiazepines and amygdala
Benzodiazepines (eg diazepam) are a common treatment for anxiert
High density of benzodiazepine binding sites in amygdala
Injection of benzodiazepines into the amygdala reduces anxiety in rats
Injection of a BZ antagonist into the amygdala abolishes the anxiety reducing effect of benzodiazepines
BUT even after amygdala destruction, BZ still have some anxiety reducing effect
Cingulate
Pain/contextual arousal
Rest/relaxation/depression
Associated areas: Orbitofrontal cortex
Anatomical connectivity- closely connected with amygdala
Functional consequences
- impulsivity (acquired sociopathy)- phineas gage
- impaired smell, taste, flavour, reward, satiety
-impairement- flexible relearning
Early PFC damage
common deficits:
- severely impaired social behaviour
- insensitive to future consequences of actions
- impaired autonimic response to punishment
- normal basic cognitive function
Early damage
- impaired social and moral reasoning (psychopathy)
- impaired decision making and autonomic response
Insula
1) representation of internal bodily state and integration of bodily feedback into awareness
2) Involved in normal response to aversive stimuli especially disgust
What about positive emotions?
Ventral tegmental area–> Nucleus Accumbens
- mesolimbic dopiminergic pathway
- reward prediction error signals
- wanting
- electrical stimulation of the medial forebrain bundle (VTA to NA) result in rats returning to the place where they receive the stimulation
- orbitoprefrontal cortex (reward value, olfactory satiety)
Dopamine
abundant in NuAcc, VTA, Striatum. PFC Dopamine apparently modulates many kinds of nerve activity in the brain Antipsychotic drugs Drugs of abuse eg amphetamines Drugs for ADHD
Dopamine: wanting or liking
Suppression of dopamine neurotransmission in humans who take a pleasurable drug does NOT suppress their reported drug pleasure even when it reduces their drug craving
Opioid NTs do appear to mediate hedonic affect or LIKING for a drug or sugar reward
thus reward does not equate Pleasure
