biology-of-fear (1).pdf

lOMoARcPSD|28762649 Biology of Fear Biological and Learning Psychology (University of South Australia) Scan to open on Studocu Studocu is not sponsored or endorsed by any colleg...

lOMoARcPSD|28762649 Biology of Fear Biological and Learning Psychology (University of South Australia) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Alexia Jones ([email protected])  lOMoARcPSD|28762649 BALP WK 6- BIOLOGY OF FEAR AMYGDALA Biology of Fear Most of the time the amygdala is quiet Amygdala is designed to detect predators A strong stimulus can result in: ADAPTIVE FUNCTIONS OF EMOTIONS - Piloerection: hair standing on end FEAR: alerts us to escape from danger - Heart racing ANGER: directs us to attack an intruder - Fight/flight hormones flooding body DISGUST: tells us to avoid things that may cause Example- RATS: illness - If rats are threatened they emit very high Emotions provide useful guide in: frequency screams - Making quick decisions and - If another rat hears this scream, a signal - Understanding/communicating needs & goes from auditory cortex (where sounds probable actions are processed) directly to amygdala - When these soundwaves penetrate rat FEAR SYSTEM OF THE BRAIN brain: amygdala is instantly activated even Pathways connecting the AMYGDALA (emotional though the rat does not ‘know’ the sound is processing system of fear) with the NEOCORTEX coming from another rat (thinking brain) are not symmetrical Connections from neocortex  amygdala are much ULTRASONIC RAT VOCALISATIONS >ABOVE 20KHS weaker than those from amygdala  neocortex INFANT DISTRESS CALLS: infants cannot regulate this may be why once an emotion is aroused, it is their own body temp and when they are cold they hard for us to turn it off at will. emit high pitched (40 kHz) distress calls The asymmetry of connections between the LONG DISTRESS CALLS: (20 kHz) when unhappy or amygdala & neocortex may help explain why stressed- e.g. defeated socially, see a predator, psychotherapy is a difficult and lengthy process experience/anticipate pain Relies on imperfect channels of communication SHORT, CHIRPING CALLS: higher pitched (50 kHz) & between brain systems involved in cognition & thought to be positive- e.g. play, courtship, feeding emotion. HUMAN AMYGDALA EFFECTS OF FACIAL EXPRESSIONS ON AMYGDALA In humans, a visual stimulus (e.g. snake) travels to Response pattern of intracranial event-related the amygdala in a few thousandths of a second potentials (ERPs) are recorded from depth- Contains cells that fire in response to electrodes in the human amygdala - Expressions of fear on faces of other Amygdala presented a preferential response to eyes humans expressing fear and joy- especially fear - Objects of fear (snakes) Special role of the amygdala in processing emotions conveyed by the eye region of the face. Downloaded by Alexia Jones ([email protected])  lOMoARcPSD|28762649 BALP WK 6- BIOLOGY OF FEAR - Interacting mental functions mediated by - Conscious memory of the accident & separate but interacting brain systems physiological responses elicited reflect 2 separate memory systems operating in EMOTION VS FEELING OF ‘FEAR’ parallel Amygdala is specialised for reacting to stimuli and PROBLEMS CONTROLLING EMOTIONS triggering a physiological response i.e. emotion of This ‘double wiring’ creates problems in humans fear Neural connections down from cortex  amygdala This is different to the conscious feeling of fear are less well developed than connections us from CLASSICAL FEAR CONDITIONING TO STUDY which arises from slower 2nd pathway (ear amygdala  cortex EMOTION amygdala  higher cortex) Amygdala exerts greater influence on cortex than Fear conditioning is used as a behavioural measure HIGHER CORTEX: analyses frightening stimulus in vice versa: once an emotion is ‘turned on’ it is of ‘fear’ that humans experience detain (using info from many parts of brain) & difficult for the cortex to ‘turn it off’ Studies using lab rats & other mammals have message is sent back down to amygdala helped map how the fear system of the brain works AMYGDALA & OTHER EMOTIONS Results in all mammal species lead to the same PHYSIOLOGY VS FEELING OF ‘FEAR’ Fear is just ONE emotion conclusion Fear is used scientifically in 2 ways: Amygdala has 12-15 distinct regions (only 2 clearly Learning & responding to stimuli warning of danger - Conscious feelings implicated in fear) involves: Neural pathways sending info about the - Behavioural & physiological responses Other emotions might be related in similar circuits outside  amygdala Joseph LeDoux suggests that: but this has not been traced yet: sexual Amygdala then determines significance of the - ‘Fear’ should denote feelings and arousal/love stimulus & triggers: emotional responses (e.g. - ‘Threat induced defensive reactions’ should freezing or fleeing) & changes in inner workings of be used for responses HUMAN EMOTION OF FEAR body organs and glands - For traumatic memory 2 memory systems are FEELINGS OF ‘FEAR’ important AMYGDALA & FEAR RESPONSES ACROSS SPECIES If fear message is a false alarm i.e. Stick not a snake EXPLICIT (CONSCIOUS) MEMORIES Amygdala of reptiles & birds similar functions: - The cortex tries to abort amygdala’s alarm - Mediated by hippocampus and other parts - Humans with damage to amygdala signals but person will have a jolt of fear, of temporal love memory system (neurological disease or surgery to control because of initial arousal of amygdala - Blood pressure & heart rate rise, begin to epilepsy) show our brains work in the same sweat and muscles tighten up way TRACING FEAR RESPONSES IMPLICIT (UNCONSCIOUS) MEMORIES Early in evolution: When fear circuit is actually traced, the - Mediated by amygdala and neural - Brain wired to produce responses to keep hippocampus and other limbic structures do not connections organism alive in dangerous situations play a big role If returning to scene of accident you remember Stimuli that trigger fear in rats and humans may be - Amygdala alone sits at centre - Where you were going, who you were with very different, but the brain’s responses to danger - Sensory info comes in and motor - Memories may cause your body to respond appear similar commands are sent out with ‘fear’ as a result of the accident In humans, once fear system detects & responds to - Emotion and cognition are separate danger our complex brain assesses what is going on Downloaded by Alexia Jones ([email protected])  lOMoARcPSD|28762649 BALP WK 6- BIOLOGY OF FEAR and tries to figure out a response which is when fear may result - To be consciously fearful you need a complex brain- aware of its own activities ANANDAMINE: the bliss molecule: messenger molecule, which influences appetite, memory, memory, pain, depression and even fertility Downloaded by Alexia Jones ([email protected])