Emotion

Introduction to Emotion

• affect: emotional states can be long orr short in duration

• mood: long-lasting, diffuse affective state without a clear trigger

  • physiological basis is poorly understood

• emotion: discrete, short duration affective srates that change in response to the environment, positive or negative reactions to particular situations

  • purpose: survival and reproduction
  • psychologists do not agree on what produces emotions
  • 3 components:
  1. physiological reaction
  2. behavioral. response
  3. feeling

Physiological Basis of Fear-Hormonal

• amygdala and other fear related brain regions control 2 pathways that produce stress hormones

  1. sympathetic adrenal medullary system (SAM system)

     1. produces catecholamine stress hormones
     2. fast

  2. hypothalamic-pituitary adrenal system (HPA axis)

     1. produces glucocorticoid stress hormones
     2. slower

• both systems produce fear related physiological responses

• SAM System

  1. Hypothalamus and hindbrain activate sympathetic nervous system neurons

  2. CNS neurons synapse directly on the adrenal medulla: inner region of the adrenal gland

  3. Adrenal medulla releases epinepherine and norepinephrine

  4. sympathetic nervous system activation

     1. activates skeletal muscles bia increased heart rare and increased glucose metabolism

     2. brain response and arousal

        

• HPA Axis

  1. Paraventricular nucleus (PVN) of the hypothalamus releases corticotropin releasing horomone (CRH) into the blood stream

  2. CRH targets the anterior pituitary gland

  3. anterior pituitary releases adrenocorticotropic hormone (ACTH) into the blood stream

  4. ACTH targets adrenal glands located on top of the kidneys

  5. Adrenal cortex: outside layers of the adrenal glands produce glucocorticoids

  6. gluticocorticoids (cortisol) and other corticosteroids:

     1. increase glucose break down
     2. increase blood pressure
     3. decrease inflamatory response

  7. fight or flight response can last minutes or hours

  8. negative feedback restores homeostasis after stressors are gone

Physiological Basis of Fear-Neural

• the limbic system is the highly conserved emotional region of the brain

• includes the:

  • hippocampus

  • amygdala

  • cingulate gyrus

  • hypothalamus

    

• amygdala: limbic system region within temporal lobes, responds ro environmental stimuli of biological significance

  • integrates behavioral, autonomic and hormonal components of fear

  • composed of 3 divisions:

  • lateral nucleus

  • basal nucleus

  • central nucleus: most important region for expression of negative emotion

    • neurons are activated by aversive/threatening stimuli
    • innately aversive: height, large animals, specific sounds or odors
    • learned via fear conditioning

    

Neural Basis of Fear and Learning

• emotions play a major role in learning

• implicit learning: non-declarative (fear conditioning)

• explicit learning: declarative, episodic, or instructed

• lateral amygdala undergoes physical changes to neurons when neutral stimulus repeatedly paired with unconditioned stimulus. and response

  

• contextual fear conditioning: aversive stimulus presented in one environment

• signaled fear conditioning: aversive stimulus presented with tone

• evidence: fear conditioning is amygdala. dependent

• amygdala. lesion impairs conditioning in animals

• patient SP with amygdala lesion

  • reports knowing that cue precedes a chock (explicit)
  • no physiological response to cue (implicit)

• extinction: emotional response is extinguished when conditioned stimulus nolinger paired with aversive stimulus

  • ventromedial prefrontal cortex (vmPFC) inhibits production of conditioned response

• amygdala modulates encoding and consolidation in hippocampus

• emotion enhances explicit memories

  • emotional episodic memories and instructed fear
  • more easily encoded recalled and retained

• amygdala lesion impairs

  • expression of instructed fear
  • enhancement of emotional memory

• central AMY: expression of fear response

• Lateral AMY: learned conditioned response

• vmPFC: extinction of learned conditioned response

• hippocampus and amygdala: explicit fear learning

Neural Basis of Aggression

• aggression: species typical threar or attack behaviors
  • linked to waiting→ access mates defend tertitory or offspring
  • self defense
• aggressive behaviors:
  • threat behavior
  • defensive behavior
  • submissive behaviors

1. cortex: percoeves approaching animal

2. limbic system: integrates innate and learned responses

   1. hypothalamus and amygdala promote sympathetic response and control PAG

3. Periaqueductal gray matter (PAG): midbrain rehion surrounding cerebral aqueduct

   1. stimulation drives aggressive attack or predation behaviors

      

• serotonin inhibits risk taking behaviors including aggression

  • antagonism increases aggressive attack

    

• testosterone: androgen gonadal hormone

  • omcrerses aggressive behavior in females and males

  • aggressiona nd T linked to reproductive behaviors

  • incresed aggression in females with high T

  • increased aggression in males with earlt T

  • T during development→ aggression

  • pubertal T→aggression

    

Neural Basis of Impulse Control

• impulsive violence may be causef by faulty emottional regulation
• ventromedial prefrontal cortex: controls emotional behavior
  • integrates automatic emotional responses and complex behaviors
  • drives. emotionally guided decisions
  • controls emotional reactions
• serotonin: serotonergic inpitts to the prefrontal cortex (PFC) regulate impulsive behavior
• emotional and impulsive violent murderers have reduced serotonin transporters in the PFC and reduced brain activity in the PFC and increased activity in the AMY
• Development: PFC is not fully developed until adulthood
  • adolescents can lack inhibition and impuls control
  • moral deciision making requires vmPFC

Communication of Emotions

• production of facial expressions- automatic conserved among humans and animals

• recognition of facial expression is automatic, rapid and accurate

• verbal expression of emotion alre also universally produced and recognized

  • emotional content of songs assessed on the 300-400ms

• lateralizatio: rihjt hemisphere more involves in the left in the comprehension of emotion

  

• amygdala activation required for recognition of fearful facial expression

• AMY inputs from:

  • cortical regions→ sloe more accurate
  • subcortical (thalamus) regions → fast

• affective blindsight: visual cortex damage but can mimic others facial expressions

• simulationist hypothesis: we percieve others expressions by imagining makin them or actually mimicking them

• right somatosensory corted activates in repsonse to facial expression

  • disruption or famage imparis the recognition of emotion

• mirror neurons activated

  • facial paralysis impairs recognition of expressions due to impaired production of own expressions?

• adinovisual mirrot neurons produce facial expressions in response to sounds

• 2 facial expression pathways: automatic and voluntary

  • damage to voluntary1 vs involuntary2:

  1. volitonal facieal paresis: damage to primary motor cortex

     1. can produce spontaneous not instructed expressions

  2. emotional facial paresis: damage to frontal lobe area

     1. can produce voluntary non emotional facial expressions

• right hemispjere is more involved than the left in production of facial expression

  • left side of the face is more expressive
  • right hemisphere lesions impair expression of emotion

Cognitive Theories of Emotion

• theories of emotion generation explain the casual link between physiological reaction, behavioral reactions subjective experiential feeling

• James Lange theory

  1. emotion producing situation

  2. physiological response: autonomic system

  3. behavioral response: skeletal. and facial muscles

  4. cognition: brain interprets

  5. subjective emotional feeling

     

     

• evidence: difficulty to measure feelings of emotion

• spinal cord damage: higher (close to brain) injuries→ less feedback from muscles and less intense feelings of anger or fear

• botox paralysis facial muscles, reduces frowning→ significantly less negative mood compared to those with other cosmetic treatments

• making fearful angry and happy faces→ physiological responses associated with these emotions

• explanations:

  1. classical conditioning: learned association between facial response and emotional response
  2. inner: inborn ability via mirror neurons, somatosensory association regions

• cannon bard theory:

  1. emotion producing situation

  2. simultaneous: subjective emotional feeling and physiological responses (autonomic and behavioral)

     

• evidence:

  • severed cat brain→ separated cortex from brain stem
  • emotional reactions occurred despite severed brain stem
  • behavior was produces however did the cat feel subjective feelings of emotion?