Biopsych

What are endogenous pacemakers

• internal biological clocks

What are exogenous zeitgebers

• factors in the sleep-wake cycle which act as external cues

• reset the biological clock of an organism

Explain circadian rhythms

• pattern of behaviour that occurs every 24h

• set and reset by environmental light levels

• influenced by internal body clocks and environmental changes

EPs and EZs work together

• Campbell & Murphy (‘98)

• found shining light at the back of ppts knees was enough to change sleep/wake cycle by 3hrs

EPs and EZs work together

• Infants

• Infant sleep wake cycle starts off random and circadian rhythms only come into effect at 6w

• schedules imposed by parents help determine sleep/wake cycle

Suprachiasmatic Nucleus (SCN)

• endogenous pacemaker located in hypothalamus and influences sleep/wake cycle as it senses light

How do we know what the SCN does?

• Ralph et al (‘90)

• Took SCN cells from mutant hamsters and put them into regular hamsters

• Sleep/wake cycle changed to 20 hours

What is the pineal gland

• produces melatonin at night which helps us sleep

AO3: Application

• Burgess et al (03)

• when travelling east to an earlier time zone, exposing skin to morning light can beat jet leg

• when travelling west to a later time zone, exposing skin to low evening light can beat jet lag

AO3: Research Support

• Morgan (‘95)

• Hamsters have SCN in forebrain

• When removed, nocturnal pattern ceased

• New fetal SCN cells implanted, regained circadian rhythm

AO3: Contradicting evidence

• studies of ppl who live in artic regions, show normal sleeping patterns despite prolonged exposure to light

Siffre’s cave study

• Circadian rhythms

• spent 61 days without seeing any daylight

• no exogenous zeitgebers

• effects of dark and loneliness were severe,  he was depressed due to his lack of freedom, became desperate for companionship.

• began to think about suicide.

• His STM was affected. He did not get the days and nights right. His periods of sleep-wake cycle were longer than 24 hours and varied from 18-52

AO3: application

• research shown that there are peak times during a circadian rhythm where drugs are better absorbed aka pharmacokinetics

• led to development of guidelines for dosage and timing of meds

Infradian rhythms

• Takes 24h to complete: menstrual, hibernation, migration, seasonal affective disorder

Infradian rhythms - monthly

Cycles of other woman can affect regularity/duration of period

• Stern & McClintock (‘98): 29 women with irregular periods, half wore pad under arms to soak up pheromones, treated and put on upper lip of other ppts

• 68% cycles affected

Infradian rhythms - evolutionary advantages

• Stern & McClintock (‘98): may be beneficial for all woman to fall pregnant at the same time bc new-borns can be raised at the same time = efficient

What is neuroplasticity

• brain’s ability to adapt to change due to illness or changes brought about due to learning and experience

What is structural plasticity

• The brain physically changes its structure based on experience.

• Neurons can form new connections or strengthen/weaken existing ones.

• Happens with learning, practice, or after injury.

AO3: Research support for neuroplasicity

Maguire et al. (2000)

• London black cab drivers spent years navigating and learning routes

• Their brains adapt by increasing grey matter in the posterior hippococampus

AO3: Research support from animal studies

Hubel & Wiesel (‘63): learnt that from sewing a kitten's eye shut, the visual cortex in the brain from the closed eye didn't stop processing visual information. Instead, it continued to process information from the closed eye

AO3: Negative plasticity

Medina et al (07): brain can sometimes rewire itself in a maladaptive way.

• e.g; drug users have poorer cognitive functioning and an increased risk of dementia in later life

What is functional recovery

• brain’s ability to replace lost or damaged functions by using existing brain regions in their place

List what happens during brains recovery

• Axonal sprouting

• Reformation of blood vessels

• Recruitment of homologous areas

• Synaptic pruning

Explain axonal sprouting

• growth of new neuron endings which connect and form new pathways

Explain recruitment of homologous areas

• Regions in the opposite hemisphere adopt functions of injured zones

Explain synaptic pruning

• The brain removes unused or weak connections between neurons to become more efficient.

• Gopnik et al (‘99): By age 2–3, a child’s brain has around 15,000 connections per neuron

• Important connections are kept and strengthened, unused ones are pruned.

Nature

• our ability to sprout new axons or create new pathways is innate. Through rehabilitation most people can recover functions in parts of their brain.

Deterministic

• neuronal change occurs as a necessity

Reductionist

• Explains changes in the brain and therefore behaviour, through physical structure only.

• It doesn't take into account the whole person or how recoveries can be different for each person, at different rates.

What is localisation of the brain

specific functions are localised and can be found in certain locations in the brain

Motor area

• located in the frontal lobe

• voluntary movements by sending signals

• motor area on one side of the brain controls movements on the opposite side of the body

Somatosensory Area

• located in parietal lobe

• receives incoming sensory information from the skin to produce sensations related to pressure, pain, temperature

Visual Area

• located in the optical lobe in the visual area

• receives and processes visual information

• info from the right-hand side visual field is processed in the left hemisphere (visa versa)

Auditory area

• located in temporal lobe

• analysing and processing acoustic information

• info from the left ear goes primarily to the right hemisphere (visa versa)

How can LOF be measured

sing brain-imaging techniques such as:

• MRI

• fMRI

• PET

Draw and label the brain

Left brain functions

• logic

• science and maths

• language

Right brain functions

• intuition

• creativity

• art and music

Where is the broca’s area located and it’s function

• left frontal lobe

• speech production

Where is the Wernicke’s area located and it’s function

• temporal lobe

• language comprehension

AO3: Supporting evidence for Broca’s area

• Broca studied a patient, could only say one word: “Tan.” but understood others

• Damage found in left frontal lobe after death 

• Evidence that specific brain regions control specific functions—in this case, language production

AO3: Research support

• Peterson et al (88)

• PET scans showed that Broca's area is active when reading; Wernicke's area is active when listening

AO3: Supporting Evidence

• Phineas Gage (1848)

• Had personality changes bc of damage in the frontal lobe caused by an iron rod piercing through his skull

AO3: Cognitive functions are shared across brain holistically rather than being localised

Lashley (‘50):

• removed rats’ cortex when they was learning to run mazes

• didn’t inhibit their ability to learn the maze

(anthropomorphism)

AO3: Gender differences

• localisation research was conducted primarily on male patients, yet findings are often generalised to women = creating beta bias bias

• assuming all brains are the same ignores potential gender differences and shows androcentrism

AO3: Individual differences

• In most right-handed people, language is mainly localised in the left hemisphere.

• However, left-handed individuals often show more bilateral or even right-hemisphere dominance for language (Knecht et al., 2000).

• so localisation cannot be assumed to be fixed

What are neurotransmitters

• chemicals that are transported via electrical impulses from the presynaptic neuron to the post synaptic neuron across the synaptic cleft

Explain the process of synaptic transmission

• electrical impulses reach the presynaptic terminal

• trigger release of neurotransmitters from synapse vesicles

• diffuse across the synaptic cleft

• bind to receptors on the postsynaptic membrane

What is action potential

• A fast electrical change in a neuron that travels down the axon to send a message.

• At rest, inside is negatively charged

• When activated, inside becomes positively charged

label a neuron

Excitatory

• receiving neuron becomes positively charged and more likely to fire

Inhibition

• receiving neuron becomes negatively charged and less likely to fire

Examples of neurotransmitters

1. dopamine

2. serotonin

What is dopamine and what effects does it have on behaviour?

A neurotransmitter known as monoamines which helps control pleasure, motivation, reward, and addiction.

• irregular levels linked to schizophrenia

• related to parkinson’s disease

What is serotonin and what effects does it have on behaviour?

A neurotransmitter known as monoamines (5-HT) which helps regulate sleep, mood and body temp

• lower levels linked to depression and anxiety

• SSRIs help prevent reuptake of serotonin

Fisher et al. (2005)

• found the link between romantic love and dopaminergic activity in the brain

Describe the divisions of the nervous system

nervous system divided into the central and peripheral nervous systems

• CNS comprises the brain and spinal cord

• the peripheral nervous system is further divided into the somatic nervous system and the autonomic nervous system (ANS)

• somatic nervous system consists of sensory and motor neurons to carry sensory and motor information to and from the CNS and also enables reflex actions

• ANS acts largely unconsciously/involuntary and divided into the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS)

• SNS prepares us for flight or fight

• PNS balances the sympathetic nervous system providing ‘rest and digest’ functions.

Describe the structure and function of a neuron.

• Neurons enable communication within the nervous system

• the cell body contains the genetic material

• dendrites extend from the cell body: carry info towards the cell body and can recieve info

• axons carry messages away from the cell body

• axon terminals contain neurotransmitters.

How did split brain patients come about

• treatment for severe epilepsy where a surgeon would cut through the corpus callosum

• This was to prevent the violent electrical activity that accompanies the seizure crossing from one hemisphere to the other.

Sperry (‘68) - procedure

• 4 diff tasks - objects, word and facial recognition tasks

• Patients were all split-brain

• Separated patients visual field into left and right

Sperry (‘68)

• Describe what you see

• Picture in right visual field = see and describe

• Picture in left visual field = unable to describe

• This is bc lang is processed in left hemisphere

Sperry (‘68)

• Recognition by touch 

• In both visual fields patients were able to select a matching item from a bag of diff objs

Sperry (‘68)

• Composite words

• Words presented on opposite sides = say the word on the right and write the word on the left

Sperry (‘68)

• Matching words

• Pictures of faces on the left were consistently selected and pictures on the right were ignored

• When a face was presented split between the visual fields, the RHS was described better

AO3: Validity

• Sperry used fixation points and presented images for 1/10th of a second

• Procedures were standardised so ppts were only able to use one hemisphere at a time = internal validity

AO3: Generalisation

• 11 ppts took part in every variation and all had epilepsy

• Argued that epilepsy causes unique changes in the brain and it’s not the exact same for all

• The study lack generalisability to the rest of the population

AO3: Contradicting research

• Kim peek exp split brain due to natural causes

• Was able to simultaneously read books 2 pages at a time

• Had fully developed lang centres in both hemispheres

• Contrasts Sperry’s findings as both hemispheres can process lang at the same time