Option A: Neurobiology

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Created on: 14-04-18 14:11

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Option A Neurobiology
- A.1 Neural Development
  - Neurulation
    - Development of the dorsal nerve chord in chordates
    - Top layer is ectoderm, middle layer is mesoderm, bottom layer is endoderm
    - First month of gestation
    - A region of the dorsal surface/ ectoderm develops differently into neuro-ectodermal cells and forms the neural plate of ectoderm cells. Cells in the neural plate change shape to fold in and form a neural groove due to signals from the notochord
      - Lateral edges of the neural plate fuse together and separate from the dorsal surface
    - Neural tube elongates as the embryo grows
    - Use a xenopus embryo (African clawed frog) to demonstrate neurulation because is transparent
  - Neuron Development
    - Cells in the neural tube divide by mitosis to produce many cells allowing the neural tube to grow and they differentiate into neurons
      - Proliferation occurs in the brain and spinal cord (CNS)
    - Neuron migration
      - 3-4 weeks after conception
      - Cytoplasm and organelles at trailing end (back) of neuron are moved to leading end (front) by contractile actin filaments
        Actin and myosin used for elongation
        
        Amoeboid movement
      - Mature neurons do not move! But dendrites might change if damaged
      - Glia provide a scaffold for ushering neurons along
      - Neurons that arrive in the brain first and are therefore older form inner layers, neurons that arrive last and are younger form outer layers
      - Neurons produced in one part of the brain might migrate to a final position elsewhere
    - Development of Axons
      - Axon: A long narrow outgrowth from the cell body that carries signals to other neurons
      - Immature neuron = Cell body with cytoplasm and a nucleus
      - Always only one axon but can have many dendrites
      - Chemical stimuli determine neuron differentiation and direction of axon development
        Sight, smell etc
        
        Sometimes, axons grow very long out of the neural tube to other parts of the embryo to form sensory and motor neurons by attaching to neurons or cells of effectors (glands or muscles)
      - Axons grow at tips
      - If the cell body stays intact, an axon can regrow as much as 5mm a day if damaged
        Providing a correct connection is established between axon and cells it should be communicating with
    - Development of synapses
      - Synapse: The junction between nerve cells where a neuron transmits a signal to another cell
      - Motor neuron axons form synapses with striated muscle fibres or gland cells
      - Minimum number of synapses a neuron could have is 2 but many form multiple synapses for more complex patterns of communication
      - Elimination and neural pruning
        Synapses formed in early development but new ones can be formed throughout life
        
        When a synapse is used, a chemical marker is left to strengthen it. When not used, no markers so synapse is weaker and gets eliminated
        
        More neurons in some parts of a baby's brain than adults so some lost in childhood
        
        Removal of dendrites and axon branches
        
        Neurons destroy themselves by apoptosis
        
        Neural pruning: Elimination of part of a neuron or a whole cell
      - Plasticity
        Ability for the nervous system to rewire its connections
        
        Throughout life but more up to age 6
        
        Important in repairing brain and spinal chord damage!!
        
        Basis of forming new memories and certain forms of reasoning
        
        Neural pruning of axons, dendrites or whole cells, growth of axons and dendrites, new synapses and elimination of synapses
        
        Occurs based on a person's experiences
    - Strokes
      - Ischemic stroke: Disruption of blood supply to a part of the brain by a blood clot or bleeding
      - Part of brain deprived of glucose and oxygen. If cell respiration cannot occur in neurons, they are irreparably damaged and die
      - In recovery, brain takes on new functions to supplement damaged areas - for 6 months after major stroke
    - Spina Bifida
      - Centrum issue caused by embryonic neural tube not closing completely in lower back from neural groove
      - Each vertebra has a centrum that supports the spinal chord and is on ventral side, tissue migrates from either side around the spinal chord and joins to form vertebral arch in front of neural tube to enclose and protect spinal chord
        Two parts of the arch never fuse
- A.2 The Human Brain
  - Development of the brain
    - Cephalisation: Development of the head
    - Forms from anterior of the spinal cord
    - Brain is control centre for body, receiving messages from spinal cord, cranial nerves and signal molecules in the blood
    - Brain allows more rapid communication between neurons
    - Major sensory organs at the anterior of the body
  - Parts
    - Cerebral hemispheres
      - Nucleus accumbens
        In both cerebral hemispheres secretes dopamine and serotonin for pleasure, reward, willpower, addictions and memory
      - Broca's area
        Left cerebral hemisphere
        
        Speech, language processing, writing and comprehension
      - Visual cortex
        Region in the occipital lobe receiving impulses from eyes
        
        Impulses from left side of field of vision in both eyes hit right side of retina and are passed to right hemisphere and vice versa
        Integration allows judging of distance and perception and size
        
        Pattern recognition and judging speed and direction of moving objects
      - Somatosensory cortex
        In the parietal lobe
        
        Sensory impulses from right side of body go to left hemisphere and vice versa
        
        Left ear impulses go to left hemisphere and vice versa
      - Motor cortex
        Left motor cortex controls striated muscles on right side and vice versa (hence a stroke causes paralysis)
        
        Posterior of frontal lobe is primary motor cortex
      - Highly complex functions like learning, memory and emotions
      - Only mammals. Reptiles and birds have a region with a cluster of cells performing similar functions
      - Frontal and prefrontal cortex
        Decision-making, planning, reasoning, morals
    - Medulla oblongata
      - Autonomic and homeostatic activities
      - Swallowing, breathing, heart rate, gut movement, vomiting, blood vessels
      - Movement of food from mouth cavity to pharynx is voluntary and controlled by cerebral cortex but down oesophagus to the stomach is controlled unconsciously
      - Chemoreceptors in blood vessels and medulla monitor blood pH. 2 regions of medulla control rate and depth of breath
        Blood pressure also monitored by receptors
      - Cardiovascular centre controls heart rate. Sends impulses to sinoatrial node
        Sympathetic nerve fibres = Speed up heart rate but decrease blood flow to gut
        
        Parasympathetic nerve fibres = Slow heart rate down using vagus nerve but increase blood flow to gut
    - Cerebellum
      - Coordinates unconscious functions
      - Balance and posture
    - Hypothalamus
      - Interface between brain and pituitary gland releasing factors to control anterior pituitary gland secretion and synthesise hormones secreted by posterior pituitary gland
    - Pituitary gland
      - Posterior lobe stores and releases hormones synthesised by the hypothalamus and the anterior lobe synthesises and releases hormones to control body functions
    - Homunculi
      - Sensory homunculus shows area of somatosensory cortex that receives inputs from that area
      - Motor homunculus shows area of motor cortex that controls muscles in that part of the body
      - Hands look huge because lots of sensory receptors and small muscles
  - Evolution of cerebral hemispheres
    - 2-4mm thick but 6 layers of neurons
    - Increase in total area leads to folds to accomodate area of the cranium
    - 0.18m squared
    - Rats have smooth cortex, cats have a few folds and elephants and dolphins have more folds. Those evolutionary closer to humans have more folds
    - Positive correlation between body mass and brain size but not directly proportional
      - Most but not all primates have a larger brain in relation to their body mass
  - Brain research
    - Lesions: Damaged areas or injury to an organ seen by autopsies or CT scans
      - Tumours, strokes or accidental damage
      - Hard to determine function because controlled by multiple areas and brain can rewire
    - Autopsies
      - Compare healthy and unhealthy brains
      - Observe behaviour / changes when they were alive to match to brain structure and position of lesions
    - Animal research
      - Local stimulation or surgery on animals' brains to see effects on the brain or behaviour
      - Ethical considerations because animals often sacrificed afterwards and suffering caused
      - Argued it has helped with discoveries into epilepsy, Parkinson's disease and multiple sclerosis
    - fMRI scans
      - Inject harmless dye and fMRI records areas of increased blood flow and therefore activity
        Oxygenated areas respond differently under scanner compared to deoxygenated areas so differences shown
      - A high resolution scan is initially taken than patients are given a stimulus and they see brain activity in response to the stimulus and multiple areas responding to it using low resolution scans
      - Diagnose ADHD, dyslexia and monitor recovery from strokes
  - Energy and the brain
    - Energy from cell respiration needed to maintain resting potential in neurons and return them to it after an action potential. Also to make neurotransmitters and other signal molecules
    - Lots of glucose and oxygen needed for the many neurons!
    - Most vertebrates use 10% energy from basal metabolism for brain. Adult humans is 20% and young children and infants is higher
- A.3 Perception to Stimuli
  - Eye
    - Rods
      - Group connections to a bipolar cell so less light needed and high sensitivity in dim light
      - High sensitivity in dim light due to many connections and summation leading to lots of action potentials
      - No colour vision and temporarily bleached in very bright light so do not work
      - Periphery
      - Wide range of wavelengths
    - Cones
      - Single connections to a bipolar cell so need a lot more light - hence low sensitivity in dim light
      - Low sensitivity in dim light due to no adding of action potentials
      - Colour vision
      - Mainly in the fovea but a small layer on the periphery
      - Colour blindness is an absence or defect in photoreceptor gene for red or green cone pigments
    - Cells
      - Retina
        Ganglion cells, bipolar cells, rods and cones, choroid, sclera
        
        Light passes through the ganglion and bipolar cells (transparent) and hits the pigments on the rods and cones. This creates an action potential which passes through bipolar and ganglion cells towards the blind spot and optic nerve
      - Bipolar cells
        If rod and cone cells are not stimulated, they depolarise and release an inhibitory neurotrasnmitter onto the bipolar cells
        Bipolar cells become hyperpolarised and do not transmit impulses to their respective ganglion cells
        
        If light is detected by the rods and cone cells, they depolarise and stop releasing an inhibitory neurotransmitter to the bipolar cells.The bipolar cell can depolarise and activate the adjacent ganglion cell
        
        Rod cells have multiple cells connected to the same bipolar cell so the brain cannot distinguish between individual rod cells so lower resolution (more grainy) image
        
        Each individual cone cell sends signals to a bipolar cell so the brain can distinguish between individual cone cells
        Higher resolution, clearer images
      - Ganglion cells
        Very long axons that pass to the brain
        
        Impulses at low frequency when no stimulation but higher frequency when bipolar cells are stimulated
        
        Ganglion cells pass across front of retina and form a bundle of ganglion cell axons forms blind spot and gap between rod and cone cells as they pass into the optic nerve and to the optic chiasma in the brain
  - Ear
    - Eardrum separates middle ear from outer ear
    - Round and oval windows separate middle ear from inner ear
    - Middle Ear
      - Eardrum and malleus, incus and stapes attached to oval window bones (ossicles)
        Articulates with each other to form a connection to the oval window to trasnmits. Oval window has a smaller surface area to amplifies sound there
        In very loud sounds, muscles contract to weakening connections between ossicles so vibrations are dampened
    - Inner ear
      - Semi-circular canals and cochlea fluid-filled
      - Cochlea transmits vibrations into neural signals
        On the membranes, there are sensory cells with bundles of hairs attached from one membrane to another. Vibrations resonate with hair cells and selective activation gives different pitches
        Hairs further in cause higher pitch which more resonance leads to greater volume
        Width and thickness of membrane gradually changes to allow different frequencies to be detected
      - Fluid is incompressible so when oval window goes in, the round window moves out and vice versa to allo oval window trnsmitsvibrtions into the cochlea
      - Hair cells are depolarised by vibrations and release a neurotransmitter which pass impulses and create to a sensory neuron and to the auditory nerve
      - Cochlear Implants
        Hair cells are defective but auditory nerve still functioning
        
        Although hearing is not fullly restored, it allows recognition of speech
        
        Outside
        Microphone to detect sounds
        
        Speech processor to select frequencies related to speechj and to filter out other frequencies
        
        Transmitter to send those processed sounds to the internal parts
        
        Inside
        Receiver picks up sound signals from transmitter
        
        Stimulator converts sound signals to electrical signals
        
        Electrodes send impulses to the cochlea and into direct contact with the auditory nerve to bypass non-functioning cochlea
        
        Implanted in the mastoid bone behind the ear
  - Receptors
    - Mechaoreceptors
      - Detects mechanical forces and movement
    - Chemoreceptors
      - Responds to chemical substances
    - Thermoreceptors
      - Detects heat
    - Photoreceptors
      - Detects light
      - Rods and cones
        Rods = One photosensitive protein/ pigment for monotone
        Nocturnal animals
        
        Cone cells = 3 types of pigments (1 blue, 1 red and 1 green)
        
        Detect image focused on retina and convert to neural signals
  - Balance
    - Semi-circular canals are fluid-filled and are at right angles to each other at a different plane
      - Detect movements of the head in any direction
    - Each semi-circular canal has a swelling at one end where it contains sensory hair cells in a gel to form a structure called a cupula
    - When the head moves in a plane the stiff wall of the canal moves too but there is a delay and inertia means the fluid lags behind. It moves the sensory hair cells and the flow of fluid triggers an impulse to the brain
    - Amount of stimulation of sensory hair cells in the different semi-circular canals determines direction of movement
  - Olfactory Responses
    - Olfactory receptor cells are in the epithelium lining the upper nose which contains cilia to move air in front of the receptors
      - Membrane is lined with only one specific receptor for a specific olfactory receptor protein
    - Olfactory receptor proteins are coded by specific genes and bind to a specific receptor (only for specific volatile chemicals)
    - Using this mechanism, animals can detect a large variety of smells usually at low concentrations, although humans have low sensitivity and precision compared to other animals
- A.5 Neuropharmacology
  - Excitation and Inhibition
    - Excitation
      - Glutamate
      - Binds to receptors on postsynaptic neuron allowing positive ion channels to open to allow Na+ and K+ to diffuse into the post-synaptic neuron
        Increases resting potential closer to threshold potential
      - -70 to -50mV
    - Inhibition
      - GABA or gamma-aminobutyric acid
      - Inhibit the formation of action potentials
      - Binds to receptors on the postsynaptic neuron allowing channels to open letting Cl- ions in or opening channels to let Na+ or K+ ions out of postsynaptic membrane
        Causes hyperpolarisation due to a lowering of resting potential and a decreased chance of depolarisation
      - -70 to -80 or more mV
    - Fast acting neurotransmitters
      - Effect a few milliseconds after release
  - Summation
    - Summation: The additive effect from multiple releases of excitatory neurotransmitter
    - Temporal summation: Threee excitatory impulses released from the same neuron
    - Spatial summation: Three excitatory impulses in succession released from different neurons
    - Excitatory + inhibitory neurotransmitters = Cancellation (a very slight increase from resting potential)
  - Slow acting Neurotransmitters
    - Noradrenaline/ norepinephrine, serotonin and dopamine
    - Hundreds of milliseconds to have an effect
    - Diffuse through surrounding fluid and affect groups of neurons
    - Binds to G protein-coupled receptor to cause release of secondary messengers inside postsynaptic neuron
      - Increase time channels are open for
      - Increase or decrease number of dendritic receptors in postsynaptic membrane
      - Protein synthesis to make enzymes, receptors and channel proteins which helps to increase number of vesicles
      - Increase number of synapses or enlarge synaptic connections
      - Chemical modification to increase rate of ion movement when neurotransmitter binds
    - Regulate fast-synaptic transmission (for relatively long periods of time)
  - Learning and Memory
    - Long-term potentiation: Repeated use of a synapse by slow-acting neurotransmitters strengthens that synaptic pathway
      - Synaptic plasticity for memory and learning
        Ability for synapses to strengthen or weaken over time due to increases or decreases in their activity
    - Long-term depression: Synaptic pathway is used less so has vesicles and receptors removed to make space for components to strengthen another pathway
    - New skills = Formation of new synapses in hippocampus
    - Longer term memories = Remodelling synaptic connections between neurons
      - More repeats of information = Stronger memory = Stronger synaptic pathway
  - Endorphins
    - Nocireceptors at the end of sensory neurons detect chemical stimuli like bee stings, needles or heat
      - When these impulses are detected by CNS cerebral cortesx, we feel pain
    - Ogliopeptides bind (block) to opioid receptors in presynaptic membranes on peripheral nervous system pathways transmitting pain
      - Natural painkiller preventing synaptic transmission and release of protein P which transmits pain
    - Secreted by anterior pituitary gland, spinal cord and hypothalamus
  - Anaesthetics
    - Produces reversible loss of sensation to part or all of the body
    - Affect sense organs and inhibit signals to motor neurons and other parts of the nervous system
    - Local
      - Prevents opening of voltage-gated sodium channels in post-synaptic membrane to prevent action potentials when pain receptors are stimulated
      - Lidocaine for dental procedures
    - General
      - Prevents uptake of Ca2+ ions into presynaptic neuron to prevent vesicle fusion with presynaptic membrane
      - Increases Cl- ion influx into post-synaptic neuron for hyperpolarisation
      - Increases K+ ion efflux out of post-synaptic neuron for hyperpolarisation
      - Causes unconsciousness by interferring with neural transmission in the brain
      - Major or delicate surgery where patients must not move
      - E.g. Propofol
    - Epidural
      - Injected into epidural space between vertebrae and spinal cord
      - Blocks sensory nerves entering the spinal cord
  - Psychoactive drugs
    - Affect personality and brain by altering functioning of some synapses
    - Excitatory drugs
      - Increase post-synaptic transmission
      - CAN!
      - Cocaine
        From leaves of Cocoa Bush grown in the Andes
        
        Blocks removal of dopamine in dopimanergic synapses by binding to reuptake transporters so more remains in the synaptic gap
        
        Highly addictive as body gradually produces less doopamine so become dependent on cocaine
        Feelings of euphoria
      - Amphetamines
        Artificially synthesised compounds
        
        Ritalin and Ecstasy
        
        Prevents removal of dopamine from dopaminergic synapses so more remains in synaptic gap
      - Nicotine
        Mimics acetylcholine neurotransmitter at cholinergic synapses
        
        Stimulates transmission and is highly addictive
        
        In cigarettes and other parts of tobacco (tobacco leaves)
        
        Increases dopamine release
        
        Pramipexole in early stages of Parkinson's disease to reduce effects of insufficient dopamine secretion. Also used as an anti-depressant
      - Mimics effect of sympathetic nervous system
      - Clinical depression or narcolepsy help
      - Caffeine and theobromine in chocolate
    - Inhibitory drugs
      - Decrease post-synaptic transmission
      - BAT!
      - Benzodiazepines
        Binds to an allosteric site on GABA receptors on post-synaptic neuron to enhance strength of GABA binding
        More Cl- ions flow in for hyperpolarisation
        
        Valium and Librion artificially synthesised as anti-anxiety drugs - also Diazepam
        
        Psychological dependence
      - Alcohol
        Same way as benzodiazepines, it enhances the strength of GABA binding
        
        Can result in addiction
        
        Fermentation of yeast to produce ethanol
      - Tetrahydrocannabinol (THC)
        Prevents uptake of Ca2+ by presynaptic neuron to prevent fusion of vesicles with presynaptic membrane
        
        Can lead to dependence
        
        Produced from leaves of cannabis plant
        
        Binds to cannabinoid receptors in the cerebellum, hippocampus and cerebral hemispheres
        
        Psychomotor behaviour, appeitie increase, intoxication and short-term memory impairment
  - Drug addiction
    - Chronically relapsing disorder characterised by 3 or more elements: Compulsion to seek and take the drug, no limit on intake and negative emotional state when access to the drug is prevented
    - Genetic make-up
      - Desensitisation, metabolism and intensity of effect determined
      - Polygenic inheritance, family members and personality could cause
    - Social factors
      - Neglect, personal trauma, poverty or social deprivation use it as an escape
      - Some cultures more prevalent due to religious contexts
      - Those in gangs more likely due to peer pressure
    - Long-term abuse leads to down-regulation of dopamine receptors meaning more dopamine needed for pleasure effect
      - Prolonged high dopamine levels make abstaining hard
- A.6 Ethology
  - Synchronised oestrus in lionesses
    - A new dominant male will kill suckling cubs so females come into oestrus quicker and at the same time and he can father cubs himself
    - All lactating at the same time so when hunting, can suckle any cub to increase chance of survival
    - All male cubs will leave the pride at 3 years and can then fight together for dominance of another group to increase chance of reprodction if they are fighting one dominant male
  - Foraging in shore crabs
    - Foraging: Searching for food
    - Choose mussels of intermediate size because energy yield greater per second of time spent breaking open the shells
    - What food to look for (optimal prey choice) and how to find it
  - Breeding strategies of salmon
    - Two types of Coho salmon; the jacks and the hooknoses
      - Jacks sneak up on females laying eggs and shed sperm over eggs
      - Hooknoses fight with each other for the females and who wins sheds sperm over the eggs
    - Breed in rivers that discharge into the North Pacific Ocean and West cost of North America
    - Jacks return to river two years after spawning and grow rapidly. Smaller so can sneak up on females
    - Hooknoses return 3 years after spawning and grow slower. Big hooknoses cannot sneak up on females so have to fight
  - Feeding on cream by blue ****
    - Peck through foil cap nd drink cream of milk
    - Less milk delivered as supermarket milk is cheaper and more skimmed milk with no cream more popular so no pecking blue **** observed recently
    - Rapid spread over Britan, Germany and Netherlands showed learned behaviour
  - Blood sharing in vampire bats
    - A vampire bat that has not fed for 2-3 consecutive nights on 25ml vertebrae blood risks death but other members regurgitate blood
      - Not kin-selection
    - Altruism: Unselfish concern or devotion for the welfare of others
    - Altruism not normally favoured as results in a cost of survival, reproduction and passing on of genes of altruisti animalbut means the donator bat could get food from recipient bat at a later time (reciprocal altruism)
      - Aids chance of survival and reproduction for all members of colony
  - Courtship of birds of paradise
    - Females favour males with more exaggerated plumage and courtship dances. Elongated tail feathers no use for flying
      - Physical fitness grow and to maintain plumage and sustain dances
    - Adapted in other ways to survive not being camoflaged
    - Gather at a site called a Lek and dances allow recognition of species to prevent interspecific hybridisation
    - Mate selection: Females with showy plumage and rigorous and spectacular courtship dances have offspring fathered by males with greater fitness. Females prefer to mate with males that have exaggerated traits
  - Migration of Blackcaps
    - Those in central Europe (Germany) used to migrate to Portugal and Spain for winter but 10% now migrate to Britain and Ireland
    - Global warming means winters are warmer in Britain so they don't have to travel as far NATURAL SELECTION because migration is genetic
    - Feed wild birds in winter so more food and greater chance of survival
    - Shortest day shorter in Britain than Spain in winter so prompts earlier migration for best territories
  - Study of actions and habits of animals in their natural environment
    - Not same stimuli so behave differently in artificial environment
  - Natural selection when individuals best-adapted and best responses to the environment are most likely to survive and produce offspring
    - House finches in California a few were released in New York and migratory behaviour observed aftger previously they stayed in the same place
    - Great **** live in woodlands and feed young on caterpillars. Peak availability is in spring but due to global warming, peak is earlier and those who lay eggs a few days earlier than mean date (narrow window of mating) have more success at rearing young
- A.4 Behaviour
  - Innate behaviour
    - Not affected by external influence
    - Genetically programmed so can inherited and can evolve with natural selection but is slower than learned behaviour
    - Palmar grasp reflex in babies up to 6 months old, spider making a web, dolphin leaping out of water, bird building a nest. REFLEXES (Withdrawal)
    - Most behaviour in invertebrates is innate
    - Quick to appear but long time to modify because needs variation and changes in allele frequencies
  - Reflexes
    - A rapid, unconscious response to a stimulus
    - Pupil reflex where radial muscles contract in iris in response to bright light to constrict the pupil
    - Involuntary response: A response without conscious thought
      - Automatic nervous system
    - Stimulus: A change in the environment. Internal or external that is detected by a receptor and elicits a response
    - Normally one or more relay neurons which are motor neurons in the grey matter of spinal cord
    - Thre are cell bodies of sensory neurons in dorsal root ganglions
  - Learned Behaviour
    - As a result of experience, offspring can acquire new patterns of behaviour during their life
    - Parents, people they are with or environment
    - Learning a language as a child. The language spoken is learned but the ability to understand is innate
    - Reflex Conditioning
      - Ivan Pavlov with the salivation reflex in dogs
      - Unconditioned stimulus = Meat powder Unconditioned response = Salivation
      - Bell = Neutral stimulus and then conditioned stimulus once association is made
      - Conditioned response = Salivation before food (unconditioned stimulus) is presented but when bell (conditioned stimulus) is rung
      - Alteration in behaviour as a result of new associations formed
      - Environment posing stimulus
    - Investigation Behaviour
      - Lab experiments allow more control and rigorous investigation but field investigations see behaviour in natural environment for validity
      - Taxis: Movement towards or away from directional stimulus
        Woodlice move away from ight
      - Kinesis: Movement as a response but not influenced by stimullus
        Speed or number of turns
      - Ensure other factors are controlled e.g. light
      - Need quantitative data for statistical tests e.g. chi squared
      - Woodlice or slaters in a choice chamber
  - Operant Conditioning
    - Burrhus Frederic Skinner created the Skinner box
    - Learning through trial and error by animal initiating it
    - Rat placed in box and explores, accidentally presses lever (operant response) and gets food reward (reinforcement)
    - Reinforcement after operant response = Quicker operant response
    - Quicker reinforcement is given, quicker operant response is developed
    - Lamb touching electric fence
  - Imprinting
    - Particular stage in life
    - Indeligible (impossible to remove) establishment of a preference or stimulus that elicits behaviour patterns but is not always trusty or recognised
    - Independent of consequences of behaviour - does not improve survival
    - At 13-16 hours, chicks attach themselves to the first moving object if they are hatched without a mother e.g. boots, another bird
      - Konrad Lorenz did this with greylag geese and they followed him and tried to mate with humans when older after he was the first moving object when they hatched
    - Learning a response to a stimulus during a sensitive period
    - Innate releasing mechanism to filter stimuli they receive
    - Sign stimulus is the stimulus that is significant that animals respond to
  - Learning and Memory
    - Learning: A higher order function of the brain involving the acquisition of skill or knowledge
    - Memory: The process of encoding, storing and accessing information
      - Short-term memory = 1 minute but long-term memory is indefinite
    - Learned behaviour: Behaviour that develops as a result of experience
      - Depends on experiences, genes to allow capacity, longevity and neural capacity
        Social animals more likely to learn from each other
      - Takes longer to appear, quick to spread, quick to disappear
    - Some behaviours are lost (palmar grasp reflex), some are modified through learning, some are acquired and others change due to growth and maturation (puberty in humans)
    - Encoding = converting information into a form that can be stored by the brain
    - Accessing = Recalling information so it can be used actively in thought processes in the brain
    - Study of HM shows the role of the hippocampus in memory
    - Through experience, large numbers of synapses are made which are gradually pruned to refine memory so that when relevant, information can be recalled
  - Birdsong Development
    - Partly innate, partly learned
    - Innate aspects of song allowing their recognition of other members of the species
    - Learn mating calls from their father and this creates differences allowing females to choose a mate based on the quality of their singing
      - Distinguish between individuals and recognise them for their song
    - Measure frequencies of sound of chaffinches normally when reared hearing other chaffinches and song of male reared in isolation in a soundproof box
      - Isolation chaffinch had same note lengths and number of notes but a narrower range and less distinctive phrases
      - Passerines

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Option A: Neurobiology

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