Biopsychology

What does the CNS do?

Controls all thoughts, body movements and allows us to interpret our external environment

What does the PNS do?

Connects the CNS to the limbs and organs in the body by sending messages back and forth

What are the two components of the CNS?

Brain & spinal cord

What are the two components of the PNS?

Somatic & autonomic nervous system

What are the two components of the autonomic nervous system?

Sympathetic & parasympathetic nervous system

Role of the somatic nervous system

To transmit information to and from the senses and to and from the CNS

Role of the autonomic nervous system

Monitors and controls the activities of the internal organs to sustain life processes

Sympathetic nervous system

Becomes more active when we are doing anything which requires the use of energy; involved in the fight or flight response that occurs when a person feels threatened

Parasympathetic nervous system

Responsible for maintaining and decreasing bodily activities; helps to control homeostasis and ensure that we conserve energy; becomes less active when the sympathetic nervous system becomes more active

What are the three types of neuron?

Sensory, relay and motor

What kind of neuron is this?

Sensory

What kind of neuron is this?

Relay

What kind of neuron is this?

Motor

Synaptic transmission

The process for transmitting messages from one neuron to the next

Excitatory neurotransmitters

Nervous system’s ‘on switches’ and increase the likelihood of post-synaptic neuron firing e.g. dopamine

Inhibitory neurotransmitters

Nervous system’s ‘off switches’ and decrease the likelihood of the post-synaptic neuron firing e.g. serotonin

Summation

If the sum of the neurotransmitters entering the post-synaptic neuron are excitatory the neuron will fire, however if the sum of the neurotransmitters entering are inhibitory the neuron will be less likely to fire

Endocrine system

A network of glands in the body that produces and releases hormone to regulate a large range of biological processes e.g. reproduction and mood

What are the three major glands?

Pituitary, adrenal and reproductive

What is released by the anterior pituitary gland?

ACTH which stimulates the adrenal glands to produce cortisol

What is released by the posterior pituitary gland?

Oxytocin which is important for mother-infant bonding

What is the pituitary gland controlled by?

Hypothalamus

What is the pituitary gland also known as and why?

The master gland because it releases hormones that influence other glands to release further hormones

Where are the adrenal glands situated?

Just above the kidneys

What is released by the adrenal cortex (outer part of adrenal gland)?

Cortisol

What is released by the adrenal medulla (inner part of adrenal gland)?

Adrenaline and noradrenaline

What is released by the ovaries?

Oestrogen and progesterone, which allows egg to mature and prepares the uterus for implantation

What is released by the testes?

Testosterone, which causes the development of male characteristics such as facial hair

Components of the HPA axis

1. Hypothalamus - releases CRF
2. Pituitary gland - releases ACTH
3. Adrenal cortex - releases cortisol

Components of the SAM pathway

1. Hypothalamus - activates the sympathetic nervous system
2. Adrenal medulla - releases adrenaline

Effects of cortisol (short-term vs long-term)

Short-term = increases blood clotting agents

Long-term = suppresses immune system

What controls the fight of flight response?

Amygdala - associates sensory signals with emotions

Effects of adrenaline (short-term vs long-term)

Short-term = increases blood pressure, HR, breathing rate, supply of oxygen to muscles, triggers the release of glucose and fats, limits non-emergency processes e.g. digestion

Long-term = increased blood pressure and heart rate are likely to cause CHD

Which part of the nervous system calms the body down after fight or flight?

Parasympathetic

Localisation of function

The capacity to carry out different functions/abilities is localised in particular areas of the cerebral cortex

Cerebral cortex

Outer layer of the brain composed of highly folded grey matter, which is responsible for higher cognitive processes, e.g. vision, movement and consciousness

What are the two hemispheres connected by?

Corpus callosum

Corpus callosum

A dense pathway of around 300 million neural fibres

What can the central sulcus and lateral fissure be used for?

To identify the location of particular brain functions and lobes

Responsibility of the motor cortex

Planning and execution of voluntary motor movement through the control of all skeletal muscles

Responsibility of the auditory cortex

Auditory perception - receives input from the ear via the auditory nerve and a sub-cortical structure called the thalamus

Responsibility of the somatosensory cortex

Skin sensation, including touch, pressure, temperature and aspects of pain; uses upside-down contralateral representation

Responsibility of the visual cortex

Visual perception

Where is the motor cortex located?

Frontal lobe, anterior to central sulcus

Where is the auditory cortex located?

Temporal lobe, posterior to lateral fissure

Where is the somatosensory cortex located?

Parietal lobe, posterior to central sulcus

Where is the visual cortex located?

Occipital lobe, posterior to lateral fissure

What is Broca’s area responsible for?

Production of spoken language, including plans for motor movement required to speak each word, which are then passed to the motor cortex

Which hemisphere is language localised to?

Left

What is Wernicke’s area responsible for?

Comprehension of spoken language

Where is Broca’s area located?

In the frontal lobe, near the motor area, anterior to the central sulcus

Where is Wernicke’s area located?

In the temporal lobe, near the auditory area, posterior to the central sulcus

What does Broca’s aphasia support (speech comprehension but impaired speech production, as a result of damage to the left frontal lobe)?

The idea that language production is localised to one specific area, as localisation of function would predict

How does Phineas Gage’s change in temperament after damaging his left frontal lobe support localisation of function?

It suggests that the frontal lobe may be responsible for mood regulation

Who re-examined the preserved brains of two Broca’s aphasic patients using MRI imaging and found that other areas of the brain besides Broca’s area were also damaged?

Dronkers et al (2007)

Who described a case in which the loss of ability to read resulted from damage to the connection between the visual cortex and Wernicke’s area, rather than the areas themselves?

Joseph Dejerine (1892)

Commissurotomy

A surgical procedure where the corpus callosum is severed as a treatment for severe epilepsy, resulting in a divided visual field

Who studied the effects of commissurotomy in split brain patients?

Sperry (1961)

Why does Sperry’s research have high individual differences?

The disconnection between hemispheres was greater in some patients than others before their commissurotomy

Why does Sperry’s research have low external validity?

Only using 11 patients with brain damage makes it hard to generalise to NT participants, who make up most of the wider population

Why does Sperry’s research have high extraneous variables?

Some patients had experienced drug therapies to reduce epileptic symptoms for much longer than other patients

Who found that hemispheric lateralisation allowed chickens to perform two tasks simultaneously (finding food and being vigilant for predators)?

Rogers et al (2004)

Who identified patient JW who even after damage to his left hemisphere and language centres recovered by developing the ability to speak from the right hemisphere?

Turk et al (2002)

Who found that 5% of right-handed participants showed a right hemispheric lateralisation for language and 75% of left-handed participants showed a bilateral representation for language?

Beaumont (1988)

Who found that language is lateralised in the left hemisphere in children and adolescents, but after the age of 25, lateralisation decreased with each decade of life?

Szaflarski et al (2006)

Neuroplasticity

The brain’s ability to constantly change to adapt to new experiences and information

Myelination

Strengthening existing pathways by wrapping more myelin sheath round the axon which electrically insulates the axon to increase its speed of activation

Synaptic pruning

Neural pathways are deleted if they remained unused, though a process of progressive weakening of pathways until they are deleted altogether

Brain trauma

Lesioning to the cerebral cortex through injury or illness which prevents normal brain functioning

Functional recovery

A type of plasticity where the brain rewires and reorganises itself during the recovery process

Recruitment of homologous areas

Recruiting similar undamaged areas in the opposite hemisphere to take over the functions that have been lost due to injury

Axonal sprouting

New nerve endings connect with undamaged neurons to form new neural pathways, creating links that were broken during the trauma

What is a practical application of research into neuroplasticity and functional recovery?

It has led to the development of neuro-rehabilitation, which aids recovery from trauma through intense physical therapy and electrical stimulation of the brain, to counteract the problems in functioning that may be experienced following trauma

Who used MRI scans to show that London taxi drivers had a significantly larger posterior hippocampus than a matched control group, which positively correlated with the amount of time spent as a taxi driver, supporting plasticity?

Maguire et al (2000)

Who found that the brain has a greater tendency for reorganisation in childhood compared to adulthood, as demonstrated by the extended practice that adults require in order to produce changes?

Elbert et al (2001)

fMRI imaging

A technique that measures changes in brain activity while a task is performed by measuring changes in blood flow as when a brain area is active more oxygen is needed and hence there is a greater blood flow - this has helped develop our understanding of localisation of function

EEG

A technique that measures general brain activity using electrodes, which record and plot brain wave patterns, providing an overall account of brain activity - arrhythmic patterns may indicate neurological abnormalities

ERP

A technique that detects very small electrical changes in the brain triggered by a specific event or stimuli - event-related potentials are always present, and other general brain activity is inconsistent, so the computer filters it out using averaging

Post-mortem

Analysing the brain after death to determine whether certain observed behaviours can be linked to structural abnormalities in the brain

Why is fMRI non-invasive with low risks?

It uses no radiation, unlike CAT and PET scans

How do fMRIs have excellent spatial resolution?

They can provide very clear and highly accurate images of within 1-2mm when identifying changes in brain activity

How do fMRIs have poor temporal resolution?

There is a five second time lag, so it can be difficult to establish which areas of the brain are responding to certain tasks

Why do fMRIs rely fully on patient co-operation?

They only work if the patient lies completely still

How do EEGs have excellent temporal resolution?

They can detect brain activity within one millisecond of it occurring

How have EEGs proven invaluable in the diagnosis of epilepsy?

They clearly present the random bursts of activity that characterise epilepsy on screen, making it easier to diagnose

Why do EEGs have poor spatial resolution?

They provide a generalised picture from thousands of neurons, so the exact source of the activity can be difficult to localise

How do ERPs have excellent temporal resolution?

They can match a stimulus to a response because they occur close together in time

What is an example of an ERP whose precise role has been described in cognitive functioning?

The P100 wave - thought to be involved in maintenance of working memory

How do ERPs have poor spatial resolution?

They don’t exactly identify where the activity is occurring and it is often difficult to eliminate general activity

How is there a lack of standardisation in ERP methodology?

Different research studies use different procedures to identify the ERP

How did post-mortems provide early knowledge and understanding of the effects of brain trauma?

They were the only way for hypotheses to be developed before scanning techniques

Why can post-mortems not establish cause and effect?

It is possible that other factors could contribute to the development of specific abnormal behaviours

Biological rhythms

Regular patterns of psychological or biological activity over a given period of time, which affect how the body works

Ultradian rhythms

Occur multiple times during a 24-hour period e.g. sleep cycles

Circadian rhythms

Occur once in a 24-hour period e.g. sleep-wake cycle

Infradian rhythms

Occur less than once in a 24-hour period e.g. SAD

Endogenous pacemakers

The body’s internal clock: biological structures in the brain affect circadian rhythms

Suprachiasmatic nucleus (SCN)

A group of neurons which regulate the actions of the pineal gland, which is responsive to light and convert serotonin to melatonin when it is dark

Exogenous zeitgebers

External cues / environmental factors that affect circadian rhythms e.g. light and social cues

What did Michael Siffre find when deprived of natural daylight for 61 days in an underground cave?

His biological rhythm remained regular but extended to just over 24 hours