Topic 3 Bio - Content

Question 1

What’s the Central Nervous System (CNS)?

Answer 1

Brain & Spinal Cord

Question 2

What’s the Brain, Spinal Cord & Neurons?

Answer 2

Brain:
- Processes incoming info from all senses

Spinal Cord:

• Connects brain to rest of the body
• Allows messages to be passed, body->brain brain->body

Neurons:

• Cells within CNS
• Communicate with lots of other cells in huge networks

Question 3

Describe & Explain the structure of the Neuron

Answer 3

Cell Body:
- Contains Nucleus: contains genetic material & mitochondria -> provides energy
Dendrite:
- Receives chemical message from another neuron, which triggers an electrical impulse (action potential)
Axon Hillock:
- Where the nerve impulse is triggered from
Axon:
- Electrical impulse travels through the axon (from the cell body to the axon terminal)
Myelin Sheath:
- Fatty insulating layer -> speeds up rate of transmission
Node of Ranvier:
- Gaps between Myelin Sheath
Axon Terminals:
- End of axon - Sends the electrical impulse from the cell body to parts of the body
Terminal Buttons:
- Electrical impulse converts to chemical message; Neurotransmitter -> are released & stored

Question 4

What’s Action Potential?

Answer 4

• Process where electrical impulse passes down the axon to stimulate the release of neurotransmitters
• Tiny electrical impulse that is triggered by a change in the electrical potential of the neuron

Resting Membrane Potential:
- Slight negative charge

When a neuron receives a message - can either stimulate:

• excitatory postsynaptic potential: depolarise neuron -> reducing charge (less negative charge)
• Inhibitory postsynaptic potential: hyperpolarise neuron -> increasing charge (more negative charge)

When it has received more excitatory than inhibitory -> action potential triggered (sends impulse along axon of neuron)

FULL PROCESS:

1. When the neuron is at rest, the inside is negatively charged
2. When the neuron is stimulated, positively charged particles enter. The action potential is initiated - neuron is depolarised.
3. After a brief period - some positive particles are pushed out of the neuron - thus the neuron moves back to its polarised state
4. Neuron has finally returned to its initial polarised resting state

Question 5

What is Synaptic Transmission?

Answer 5

• When electrical message reaches the terminal button -> turns to a chemical message
• Neurons can then pass its message to other neurons across the synaptic gap (space between 2 neurons)

PROCESS:

• Action potential reaches axon terminal
• Calcium channels open
• Calcium ions flood the terminal buttons
• Vesicles contain neurotransmitters which are released & travel to the outer membrane of the terminal button
• Casing of the vesicle fuses with the outer membrane
• Neurotransmitters (which are released from the vesicles) travel to the synaptic gap
• Receptors on postsynaptic neuron are designed to bind to a specific neurotransmitter - once detected, it will be absorbed
• Unabsorbed molecules left in the synaptic gap will be destroyed by enzymes or absorbed again by the presynaptic neuron (reuptake)

Question 6

What are the examples of neurotransmitters & what do they mean or do?

Answer 6

Dopamine:

• Related to emotion & cognitive function
• Posture + control of movement
• Reinforcement in learning
• Dependency (e.g. addiction)
• Hormonal regulation

Serotonin:

• Mood control (esp in limbic system)
• Pain
• Sleep
• Hunger
• Regulating body temperature

Acetylcholine:

• Stimulates muscle contractions
• Necessary for memory + other cognitive functions
• Involved in expression of some emotions (e.g. anger & sexuality)

Noradrenaline:

• Associated with emotion, esp in mood control
• Sleeping
• Dreaming
• Learning

Question 7

What are Recreational Drugs?

Answer 7

• Chemicals taken by personal enjoyment

- Alter brain functions changing mood, perception or conscious experience

Question 8

What’s a Reward Pathway?

Answer 8

• group of brain structures
• When activated -> gives a pleasant & rewarding feeling
• Feeling encourages to repeat behaviour

Question 9

Why are some drugs called ‘psychoactive’?

Answer 9

affect mental processes, e.g. perception, consciousness, cognition or mood and emotions
- Not always used as recreational drugs
(medical cannabis & marijuana)

Question 10

What is the Dopamine system & why is it important when trying to understand recreational drugs?

Answer 10

• Pathway in the brain, operates on the neurotransmitter dopamine, release of which leads to feelings of reward
• All recreational drugs increase dopamine release
• Stimulate the ventral tegmental area (VTA) & nucleus membrane: nucleus accumbens creates a sense of pleasure when activated, produces more dopamine

Question 11

How does heroin (recreational drug) effect the dopamine system?

Answer 11

• Heroin increases amount of dopamine in reward pathways of the brain (the nucleus accumbens & VTA) by boosting the activation of dopaminergic synapses -> pleasurable experience/euphoria
• Heroin is an opioid -> depressant effect on CNS -> slows down CNS activity
• When heroin for injected, morphine binds with a specific receptor at the synapse found in cerebral cortex, lambic system & hypothalamus
• Endorphins & enkephalins are produced by the body as natural painkillers; Heroin taps into this system by binding with the receptors of the natural opioid system -> enhance the natural response
• Is an agonist drug as it mimics the action of another natural biochemical
• Repeated use of heroin -> opioid receptors on postsynaptic neutrons are constantly with morphine molecules -> desensitises them to the effect of the drug

Question 12

What is brains natural response to a sudden increase in dopamine & what is the consequence of the sudden increase in dopamine from the brain?

Answer 12

• Brain reacts to sudden increase of dopamine & reduces natural production so when the drugs wear off they have less dopamine than normal (unpleasant experience/dysphoria)
• Motivates ppl to take more of the drug to feel euphoria (dopamine)

Question 13

What do we mean by withdrawal?

Answer 13

• ## Symptoms a person experiences when not using a substance, due to the body reacting to no longer having the substance.

Question 14

What is meant by tolerance?

Answer 14

• When the user takes greater doses of the drug to get the same effect as on the previous occasions when they took it because the brain adapts to high lvls of dopamine caused by the drug & down-regulates it’s own natural production

Question 15

What are the mode of action of recreational drugs?

Answer 15

• Nicotine

- Cocaine

Question 16

How does Nicotine work? (what is its mode of action)

Answer 16

• Targets parts of the dopamine pathway & increases the amount & transmission of dopamine
• Mimics Acetylcholine
• Binds to the Nicotinic receptors

Question 17

How does cocaine work? (what is it’s mode of action?)

Answer 17

• Increases activity in dopamine pathways

- Blocks reuptake of dopamine

Question 18

How do the Mode of action drugs (Nicotine, Cocaine) lead to addiction?

Answer 18

• Withdrawal occurs when drug is no longer active in our nervous system
• Brain adapts to the changes caused by the drug so no longer operates normally without the drug

Question 19

What is the historical view of brain structure?

Answer 19

• Trepanning used in connection of migraines & epilepsy

- Hippocrates (Greek Physician) said each hemisphere have a diff function

Question 20

What are case studies that indicated aggression in the brain?

Answer 20

Phineas Gage
- Accident -> Iron rod through Gage’s skull -> Damage to Frontal Cortex (involved in personality & behaviour) -> Caused personality change; became irresponsible & aggressive

Paul Broca (neuroscientist) 
- Studied stroke patients -> One patient known as 'Tan' lost the ability to speak but only knew how to say Tan -> examination shown damaged in the lower part of the left frontal lobe (responsible for speech production)

Charles Whitman

• Murdered family & strangers then committed suicide
• Autopsy carried out -> Brain tumour pressing on his amygdala (decision making, emotional reaction & memory processing)

Question 21

What are the 4 lobe of the brain?

Answer 21

• Frontal lobe
• Temporal lobe
• Parietal lobe
• Occipital lobe

Question 22

What are the types of aggression activated when there’s lesion/stimulation to the different areas of the brain?

Answer 22

• Medial Hypothalamus = Offensive Behaviour
• Dorsal Hypothalamus = Defensive Behaviour
• Lateral Hypothalamus = Predatory Behaviour

Question 23

Which Brain structures are involved with aggression?

Answer 23

Midbrain:
- contains an area called periaqueductal grey matter (PAG) -> pain, threat & defensive behaviour
- links amygdala, hypothalamus with prefrontal cortex
Limbic System:
- Includes hippocampus, amygdala & hypothalamus
- Behaviours needed for survival (eating, fight & flight response)
Hypothalamus:
- Maintains homeostasis -> regulates hormones
- Linked to aggression in males (testosterone)
Amygdala:
- Centre for emotional & aggressive behaviour
- Damage -> problems emotional reactions, decision making
- Connected to Prefrontal cortex (this linkage may lead to aggression)
Prefrontal cortex:
- Controls social interaction, regulation of behaviour & emotions
- Left regulates positive emotions & right negative emotions
- Damage leads to anger management, irritability & impulse control

Question 24

What are the strengths for brain structure involved with aggression?

Answer 24

Support/Evidence from Case Studies:

• Phineas Gage - Charles Whitman
• Raine et al - Paul Broca

Animal comparison to humans:
- Even though there are differences, some may argue that the basics are the same -> so animal exps are beneficial

Narabyashi (1972) -> 43/51 patients had aggression reduced -> had their amygdala removed

Question 25

What are the weaknesses for brain structure involved with aggression?

Answer 25

Ethical concerns for animals: - Research is immoral as the animals are harmed Comparing animals to humans : - Differences between animals & humans -> diff genotypes to humans -> human brain more complex Support/Evidence from case studies: - 1 sample -> unrepresentative -> Cannot generalise findings to all brain patients -> lacks external validity

Question 26

What is evolution?

Answer 26

- Gradual development of organisms - Happens by Natural Selection (organisms better adapted to their environment reproduce more, passing on genes) - Variation is due to mutations - Psychologists argue mind evolves like the body (and behaviour)

Question 27

How is Evolution linked to Behaviour?

Answer 27

- Brain built due to inherited genes - Structure + function of brain evolved to serve an adaptive function in the Environment of evolutionary adaptation (EEA) - EEA unique to each species as ancestors faced different conditions - In EEA, successful humans were those that suited the env -> parental investment, mate choice, etc.

Question 28

How is Evolution linked to Aggression?

Answer 28

- Males naturally more aggressive when resources threatened/hunted -> adaptive advantage -> more prepared to attack & provide for their families -> ALSO advantage on mate choice, females chose mates who were strong & big as are more likely to provide better for them (food & protection) -> aggressive traits favoured - Females less physically aggressive (evolutionary disadvantage) -> at risk in conflict & hunting. Females more verbal & emotional -> chose mates by degrading other females to potential mates to make these women appear less attractive

Question 29

What are the strengths for Evolution linking to Aggression?

Answer 29

- Males & Females have different brain structures due to high lvl of testosterones -> linked to males being aggressive & females being nurturing & caring - Supports idea of adaptive advantage Chester et al (2015) -> males with low activity in MAOA gene linked to increase lvls of aggression - deficits of MAOA gene -> inability to regulate aggression

Question 30

What are the weaknesses for Evolution linking to Aggression?

Answer 30

Aggression leading to risk: - if males are aggressive to ensure protection of mates/offspring -> males are at risk -> fighting another human may lead to death -> cannot pass genes Evolution theory is developed to fit facts - difficult to prove these ideas -> cannot be scientifically tested - limited fossil records for behaviour -> although theory makes sense, cannot be empirically tested

Question 31

What is Freud's Psychodynamic Explanation?

Answer 31

- Aggression begins with 2 innate drivers -> motivation for all human behaviour - Eros -> life instinct (enjoyment & preservation) - Thanatos -> death instinct - Both have to balance each other out -> prevent us from hurting ourselves Id: made up of the 2 drives (Eros & Thanatos) - ENTIRELY Unconscious - From birth - 2 yrs old - Pleasure principle -> demanding urges to be satisfied Ego: Appears around 2 yrs old - Conscious - Reality principle - Urges of id controlled/delayed (still doesn't know right from wrong) - Norms/rules of society learned Superego: 3-6 yrs old - Unconscious - Morality Principle - Develops understanding of right & wrong - Pride/guilt - Aggressive urges well controlled when superego well developed

Question 32

What is the evaluation for Freud

Answer 32

Strength: Can explain different types of aggression: - 'hot-blooded' = impulsive, no purpose other than its own satisfaction -> id fully taken over - ego can't control id - 'cold-blooded' = purpose behind the anger, deliberate -> outcome of the ego control of id impulses Catharsis beneficial to society/life - helping reduce aggression - feature in therapy Weaknesses: Releasing anger is not cathartic but only causes more aggression - Bushman (2002) -> Made students angry criticising their essays they wrote -> a group vent anger by hitting a punchbag whilst thinking about confederate -> this group more aggressive compared to the other group that didn't vent (release catharsis)

Question 33

What is Catharsis?

Answer 33

Thanatos is mainly directed at ourselves but due to interacting with others, it's redirected to others in the form of aggression. BUT not always aggressive due to catharsis -> satisfying urges without violence by watching violence or partaking in minor violence (video games/sports)

Question 34

What are Hormones?

Answer 34

Chemical messengers that transmit info around the body - Carried in the blood & operate all around the body (not just in the CNS like neurotransmitters) - Produced by glands in endocrine system

Question 35

What is Testosterone?

Answer 35

- An Androgen -> develops/maintains male characteristics

Question 36

What does Antenatal exposure do to testosterone?

Answer 36

- Organising effect on developing brain - Increased spatial ability - Competitiveness aggression

Question 37

What happens after birth in terms of testosterone?

Answer 37

- Testosterone sensitises certain neural circuits - Stimulates cell growth in areas of the hypothalamus & amygdala -> later as an adult sets up the action of testosterone to effect aggression

Question 38

What are the animal studies to back up info on testosterone?

Answer 38

Castrated Male Rodents -> castration stops production of testosterone -> showing no aggressive behaviour but if injected back -> shows aggressive behaviour - there's a different effect depending on age - newborn -> no effect - 10 days old -> injection brings back normal lvls Young et al (1959) -> injected pregnant monkeys w/ testosterone - offspring (m+f) more aggressive Adelson (2004) -> rats - aggression control centres in the brain electrically stimulated -> raising stimulation of aggression

Question 39

What are human studies that back up info on testosterone?

Answer 39

Mazur (1983) -> test, early teens - levels increase in early teens & there's a strong positive correlation with aggressive behaviour & inter-male fighting Dabbs (1988) -> looked at female prisoners & test - higher in unprovoked violence - lowest where aggression was defensive Barzman (1978) -> looked at 17 children in a hospital -> aimed to find hormones in saliva related to aggressive behaviour -> recorded aggression using rating scales (observing & answering Q's) - Higher aggression score of those boys noted as aggressive than for boys called "not aggressive"

Question 40

What is the evaluation of study findings of humans & animals?

Answer 40

STRENGTHS: - Trainor (2009) -> rodents & humans have similar hypothalamus & limbic system for both to be able to generalise - WEAKNESSES: - Although mice & humans share 90% dna -> differences between both -> findings on mice can't be generalised to humans -> social behaviour difference - Experimental research carried out on animals -> can't be carried on humans (injecting in rodents)

Question 41

Individual Differences