Lecture 5: Biopsychology of Emotion, Stress and Health

Darwin’s theory (biopsychology of emotion)

-help build social connections to aid survival

-help avoid certain situations

-allows more effective communication

-emotions are observed in all species and lots of similarities in how we express our emotions

animals and emotion (biopsychology of emotion)

-evolved to express and process emotions

-must serve an important function if it has evolved

-can connect with people who don’t have the same language (humans + animals)

-animal expressions indicate what they are likely to so next

-opposite messages are often signalled by opposite movement and postures

physiology of emotions

-associated with the autonomic nervous system

-have biological response which leads to a range of physiological reactions as well as, the emotional response too

James-Lange theory (physiological theories of emotion)

-suggests any emotion induced sensory stimuli are received and interpreted by the cortex

-this triggers changes in the visceral organs via the autonomic nervous system and in the skeletal muscles via the somatic nervous system

• stimuli → physiological arousal → emotion

Cannon-Bard theory (physiological theories of emotion)

-emotional stimuli have two independent excitatory effects

-excite both the feeling of emotion in the brain and expression of emotion in the autonomic and somatic nervous systems

-parallel process that have no direct causal relation

physiological arousal

• stimuli →

  emotion

two-factor theory (physiological theories of emotion)

-each of the three principal factors in an emotional response can influence the other two:

• perception of emotion inducing stimulus

• autonomic and somatic responses

• experience of the emotion

-propose that all the aspects interact

-all three principles are relevant and do not act independently

emotions and the autonomic nervous system

-not all emotions are associated with the same pattern of ANS system

-no evidence to say that each particular emotion is characterised by a distinct pattern

behavioural characteristics of fear

-protecting others

-submission

-wide eyes

-using hands to protect

fear

-emotional reaction to a threat

-easiest emotion to infer from behaviour

-way species express fear is very similar

-plays an important adaptive function in motivating the avoidance of threatening situations

-chronic fear is a source of stress and is no longer adaptive

fear conditioning: animals

-establishing of fear in response to a previously neutral stimulus (CS) by presenting it before the delivery of an aversive stimulus (US)

fear conditioning process (animals)

-rat hears a tone (CS) and receives a mild electric shock (US)

-after several pairings of the tone and the shock, the rat responds to the tone with a variety of defensive behaviours (CR)

-now associates tone with electric shock

before fear conditioning (humans)

-neutral stimulus is a white rat

-Albert shows curiosity (NR)

-unconditioned stimulus is a loud noise → naturally fearful of loud noises and leads to Albert being upset (UCR)

during fear conditioning (humans)

-the neutral stimulus of the rat is paired with the unconditioned stimulus of the loud noise

-leads to a response of Albert crying

after fear conditioning (humans)

-the rat is now a conditioned stimulus

-when Albert is exposed to the conditioned stimulus he shows the conditioned response of fear and crying without the loud noise

-associate the rat with the loud banging

amygdala (fear conditioning)

-receives input from all sensory systems and retains and learns the emotional significance of sensory signals

-several pathways carry signals from the amygdala to brainstem structures that control the various emotional responses

-damage/lesions of the amygdala can affect fear conditioning

PAG region (fear conditioning)

-pathway that receives signals from amygdala and elicits a behavioural response

hypothalamus (fear conditioning)

-communicates with amygdala

-hypothalamus elicits sympathetic nervous system response → increases arousal

Kluver-Bucy syndrome (fear and amygdala)

-observed in monkeys whose anterior temporal lobes were removed

-consume almost anything that is edible, increase in sexual activity aimed at inappropriate objects

-lacked fear

patient S.M (fear and amygdala)

-bilateral amygdala destruction

-compared to brain damage controls

-had to show a range of emotions

-no difference in other emotions across conditions

-patient S.M showed a very low fear response compared to controls

limbic system and emotion (brain mechanisms involved in human emotion)

-Papez proposed emotional expression is controlled by several interconnected nuclei and tracts that ring the thalamus

-emotional states are expressed through the action of the other structures of the circuit on the hypothalamus and that they are experienced through their action on the cortex → which causes the behavioural response

brain mechanisms involved in human emotion

-medial portions of prefrontal lobes are the sites of emotion-cognition interaction

-functional brain imaging studies have found evidence of activity in medial prefrontal lobes when emotional reactions are being cognitively suppressed or re-evaluated

-hippocampus plays a role in remembering experiences and this influences how we behave and respond in the future

cortex and emotion (brain mechanisms involved in human emotion)

-brain receives input from sensory cortex, which feeds into emotion processing

-motor cortex involved in output

-similar patterns of brain activity in motor and sensory cortices tend to be recorded when a person experiences an emotion, imagines that emotion or sees somebody else experience that emotion

right hemisphere model (brain mechanisms involved in human emotion)

-proposes the right hemisphere is specialised for all aspects of emotional processing

-simplistic

valence model (brain mechanisms involved in human emotion)

-proposes the right hemisphere is specialised for processing negative emotions

-left hemisphere is specialised for processing positive emotion

current perspectives (brain mechanisms involved in human emotion)

-emotional situations produce widespread increases in cerebral activity

-all brain areas activated by emotional stimuli are activated during other psychological processes

-no brain structure linked to a specific emotion

-same emotional stimuli can activate different areas in different people

stress

-mental, physical, emotional and behavioural reactions to any perceived demands or threats

stressors

-anything that places an unusual demand on us

-can be:

• physical

• personal

• social

mechanisms of stress

-historically stress was physical → needed to survive physical attacks

short term: stress response

-stress produces adaptive changes that help animal respond to stressor

• stress response → activation of anterior pituitary adrenal-cortex system

• stressors → activate sympathetic nervous system, increasing the amount of adrenaline and noradrenaline released from the adrenal medulla

positive stress (types of stress)

-brief increase in heart rate

-mild elevations in the stress hormone

tolerable stress (types of stress)

-serious, temporary stress responses

-buffered by supportive relationships

toxic stress (types of stress)

-prolonged activation of stress response systems in the absence of protective relationships

-can trigger autoimmune and other health conditions

adaptive immune response (stress and the immune system)

-presence of an antigen

-recognition of the antigen

-immune system defence response

-antigen defeated

-immune system has specific antibodies

• slower reaction

innate immune response (stress and the immune system)

-anatomic barrier

-reacts quickly near to the point of entry

-phagocytes

-causes inflammation

• response is faster and not specific to any antigen

sympathetic division (arousal)

-pupils dilate

-salvation decreases

-skin perspires

-respiration increases

-heart accelerates

-digestion inhibits

-adrenal glands secrete stress hormones

-immune system function is reduced

parasympathetic division (calming)

-pupils contract

-salvation increases

-skin dries

-respiration decreases

-heart slows

-digestion activates

-adrenal gland decreases secretion of stress hormone

-immune system function is enhanced

stress, fear and anxiety

• stress → physiological and psychological response to demands

• fear → emotional response to perceived or actual threat

• anxiety → anticipatory response to unknown threat