biopsychology

What is the nervous system

• A specialised network of cells in the human body

• Consists of the central and peripheral

• Communicates using electrical signals

• To collect, process and respond to information in the environment

• To coordinate the working of different organs and cells in the body

The CNS

• the brain

• The spinal cord

Peripheral nervous system

• Transmits messages to and from cns

• Autonomic nervous system

• Somatic nervous system

Autonomic nervous system

• Governs vital functions in the body such as breathing and heart rate

• Sympathetic NS- fight or flight

• Parasympathetic- relax the body after

Somatic NS

Governs muscle movement and receives information from sensory receptors

Endocrine system

• instructs glands to release hormones into bloodstream

• The hormones are carried towards target organs in the body

• Communicate via chemicals

Fight or flight response

• the way an animal responds when stressed

• The body becomes physiologically aroused in readiness to fight or flee

• For example being chased by a bear

Adrenaline

• a hormone produced by the adrenal gland

• Responsible for fight or flight

What is a neuron

• the basic building blocks of the nervous system

• They are nerve cells that process and transmit messages through electrical and chemical signals

3 types of neuron

• Sensory- carry messages from PNS to CNS, long dentrites, short axons

• Relay-connect the sensory neurons to the motor or other relay neurons- short dentrites and axons

• Motor- connect CNS to effectors such as muscles- short dentrites, long axons

Structure of neuron

What is synaptic transmission

The process by which neighbouring neurons communicate with each other by sending chemical messages across the gap (synapse)

neurotransmitter

• Brain chemicals released from synaptic vessels that relay signals across the synapse from one neuron to another

Excitation

• when a neuro transmitter such as adrenaline increases the positive charge of the postsynaptic neuron

• this increases the likelihood that the person synaptic neuron will pass on the electric impulse

Inhibition

• when a neuro transmitter such as serotonin increases the negative charge of the postsynaptic neuron

• this decreases the likelihood that the person synaptic neuron will pass on the electric impulse

what is localisation

The theory that different areas of the brain are responsible for different behaviours in the body

Brockas area

an area of the frontal lobe in the left hemisphere responsible for speech production

Wernickes area

an area of the temporal lobe in the left hemisphere responsible for language comprehension

Strengths of Localisation

+EVIDENCE FROM NEUROSURGERY- damage to the brain has been linked to mental disorders- neuro surgery is a last resort for treating mental disorders by targeting specific areas of the brain which may be involved- E.G cingulotomy involves isolating a region called cingulate gurus which has been implicated with OCD- 44% of people it was successful for - this suggests the behaviours associated with serous mental disorders maybe be localised

+EVIDENCE FROM BAIN SCAN- Petersen used brain scans to demonstrate how Wernicke’s area was active during a listening task and Broca’s area was active during a reading task- these studies confirm localised areas for everyday behaviours- therefore objective methods for measuring brain activity have provided sound scientific evidence that many brain functions are localised

Weaknesses of localisation

• Language may not be localised to just Broca’s and Wernicke’s area

• Tremblay and Dick found that only 2% of modern researchers think that language in the brain is completely controlled by Broca’s and Wernicke’s area

• Advances in brain imaging techniques such as fMRI mean that neural processes in the brain can be studied with more clarity than ever before. It seems that language function is distributed far more holistically then first thought

• This suggests that, rather than being confined to a couple of key areas, language may be organised more holistically which contradicts localisation

What is hemispheric lateralisation

The idea that the 2 halves of the brain are functionally different and certain mental processes and behaviours are mainly controlled by one hemisphere rather than the other

Split brain research

A series of studies involving people with epilepsy who had experienced a surgical separation of the two hemispheres of the brain to reduce the severity.

Sperry’s research procedure

• A study on how to separated, hemispheres deal with speech and vision

• Procedure = 11. People who had a split brain operation was studied using a special set up in which an image could be projected to the participants RVF, and the same or different image could be projected to the LVF, In a normal brain, the corpus callosum would immediately share the information, however, presenting the image to one hemisphere of a split brain Participants meant that information could not be conveyed from one hemisphere to the other

Sperry’s research findings

• when a picture were sent to the participants RVF the participant could describe what they saw but they could not do this. If the picture was showing to the LVF

• This is because messages from the RHI relate to the language centres in the LH, but it is not possible in the split brain

• Although participants could not give verbal labels to object projected to the LVF, they could select a matching object out of sight is on the left hand, which is linked to the right hemisphere

• These observations show have certain functions are lateralised in the brain and support the view that LH is verbal and right hemisphere is emotional

Strengths of split brain reasearch

+EVEN IN CONNECTED BRAINS THE TWO HEMISPHERES PROCESS INFORMATION DIFFERENTLY

• Fink used PET scans to identify which areas were active during visual processing tasks when participants with connected brains were asked to look at pictures that RH was more active

• This suggests that hemispheric lateralisation is a feature of the connected brain as well as split brain

+SUPPORT FROM MORE RECENT RESEACH

• Gazzinga showed that split brain participants actually perform better than connected controls on certain tasks. This is because they were faster at identifying the odd one out in an array of similar objects than normal controls.

• In a normal brain, the LH is better cognitive strategies are watered down by the inferior RH

• This supports berries earlier findings that the left brain and Right brain are distinct.

Weaknesses of hemispheric lateralisation

-the idea that the LH as analyser and RH as synthesiser might be wrong

• research suggests people do not have a dominant side of their brain which creates a different personality. This is shown by a study that analysed brain scans from over 1000 people aged 7 to 29 years old and did not find people used certain hemispheres for certain tasks, but there was no evidence of a dominant side.

• This suggests that the notion of right or left brain people is wrong

-CASUAL RELATIONSHIPS ARE HARD TO ESTABLISH

• The behaviour of Sperry’s split brain participants was compared to a Neurotypical control group

• An issue though is that none of the participants in the control group had epilepsy. This is a major confounding variable.

• Any differences that were observed between the two groups may be the result of the epilepsy rather than split brain

• This means that due to some of the unique features of the split brain participants cognitive abilities might have been due to their epilepsy

Brain plasticity

This describes the brain’s tendency to change and adapt as a result of experience and new learning, which generally involves the growth of new connections

Functional recovery

• form of plasticity

• Following damage through trauma, the brain’s ability to redistribute or transfer functions, usually performed by a damaged area to other and damaged areas

Maguire research into plasticity

• Studied the brains of London, taxi drivers, and found significantly more volume of grey matter in the posterior hippocampus than matched control group

• This part of the brain is associated with the development of spatial and navigation skills in humans and other animals

• As part of their training, London cabbies must take a complex test called the knowledge which assesses the recall of city streets and possible routes

• Maguire found that this learning experience alters the structure of taxi drivers brains. They also found that the longer the taxi drivers had been in the job. The more pronounced was the structural difference.

Axonal sprouting

The growth of new nerve endings which connect with other and damaged nerve cells to form new neural pathways

Denervation supersensitivity

This occurs when axons that is a similar job become aroused to a higher level to compensate for the ones that are lost

Recruitment of a homogenous areas

Similar areas on the opposite side of the brain which are damaged can be performed

Evaluation of plasticity

-MAY HAVE NEGATIVE BEHAVIOURAL CONSEQUENCES

• evidence has shown that the brain is adaption to prolonged drug use leads to Paul at cognitive functioning in later life, as well as an increased risk of dementia

• This suggests that the brains ability to adapt to damage is not always beneficial

+PLASTICITY MAY BE A LIFE LONG ABILITY

• Bezzola demonstrated have 40 hours of golf training produced changes in the neural representations of movement In participants age 40 to 60

• Using fMRI The researchers observed increased motor cortex activity in golfers, compared to a control group, suggesting more efficient, neural representations after training

• This shows that Neuroplasticity can continue throughout the lifespan

Evaluation of functional recovery

+RWA

• understanding the processes involved in plasticity has contributed to the field of neuro rehabilitation

• By simply understanding the accident, no growth is possible, encourages new therapies to be tried. E.g constraint induced movement therapy used for those who have suffered with a stroke

• This shows that research into functional recovery is useful as it helps medical professionals know when interventions need to be made

-LEVEL OF EDUCATION MAY INFLUENCE RECOVERY RATES

• Schneider revealed that the more time people with a brain injury had spent in education, the greater the chance of disability free recovery

• 40% of those who achieved DFR had more than 16 years education compared to about 10% of those who had less than 12 years education

• This would imply that people with brain damage who have insufficient DF are less likely to achieve a full recovery

fMRI

• A method used to measure brain activity while a person is performing a task

• It detects which regions of the brain are rich in oxygen and thus active

Strengths of fMRI

• Non invasive as it doesn’t rely on the use of radiation

• Produces images that have very high spatial resolution

Weaknesses of fMRI

• it is very expensive compared to other techniques

• Paul temporal resolution as there is a five second time lag

EEG

A record of the tiny electrical impulses produced by the brain’s activity

Strengths of EEG

• has been useful in studying the stages of sleep and diagnosis of conditions, such as epilepsy

• Hi, temporal resolution with the single millisecond

Weaknesses of EEG

EEG doesn’t pinpoint exactly source of neural activity

ERP

Records different types of brain waves are triggered by particular events

Strength of ERP

• More specificity to the measurement of neural processes, then could ever be achieved using raw EEG data

• ERP frequently used to measure, cognitive functions and deficits

Weakness of ERP

lack of standardisation, making it difficult to confirm findings

Post-mortem examinations

The brain is analysed after death, to determine where the satin absorbs behaviours during the persons lifetime can be linked to structural abnormalities in the brain

Prince of post-mortem examinations

Vital in providing foundation for early understanding of key processes in the brain

Weaknesses of PME

Raise ethical issues of consent from the individual before death

Biological rhythms

• Distinct patterns of changes in the body activity that conform to cyclical time period

• They are influenced by the internal body clock (endogenous pacemakers) and external changes to the environment ( exogenous pacemakers)

Circadian rhythms

Biological rhythms, subject to 24 hour cycle, which regulate a number of body processes such as the sleep wake cycle

Siffre’s cave study

• spent several months underground to study the effects of his own biological rhythms

• He was deprived of exposure to natural light and sound, but with access to adequate food and drink

• Found his body clock was around 25 hours

Evaluation of circadian rhythms

+Provides an understanding of the consequences that occur during shift work

• For example, night workers engaged in shiftwork, expensive period of reduced concentration at six in the morning mean the stakes are more likely

• This shows that research into the sleep, wake cycle have a real world economic implications in terms of how best to manage worker productivity

-however, studies investigating the effects of shiftwork tend to use correlation methods, meaning it is difficult to establish whether the synchronisation of the sleep wake cycle is actually a cause of negative effects

+Improve medical treatments

• circadian rhythms, coordinate a number of The bodies, basic processes, such as heart rate

• These rise and fall during the course of a day, which has led to the fieldwork of how medical treatment can be administrated in a way that corresponds to a persons, biological rhythms

• For example, aspirin produces blood platelet activity, and this can reduce the risk of heart attacks

• This shows that the rhythms research can help increase the effectiveness of drug treatments

-individual differences are ignored

• Studies are based a very small samples and are mainly men

• This means it is not generalisable and is difficult to use research to discuss anything more than averages, which may mean it’s meaningless

Infradian rhythm

The type of biological rhythm, with a frequency of less than one cycle in 24 hours, such as menstruation

Evaluation of infradian rhythms

+ May be explained by natural selection

• synchronisation of the menstrual cycle is thought to have some evolutionary value

• for our distant ancestors, it may have been an advantage for women to men straight together, and become pregnant at the same time, as it would allow babies to have lost their mother to have access to breastmilk, which improves their chances of survival

• This suggests that synchronisation is an adaptive strategy

-Methodological limitations

• there are many factors that may affect change to the menstrual cycle, including diet

• These may act as confounding variables, meaning that any suppose the pattern of synchronisation is no more than what we would’ve expected to occur by chance

• This suggests that the menstrual synchrony studies are flawed

UltradIndian rhythms

Type of biological rhythm with the frequency of more than one cycle in 24 hours, such as the sleep cycle

Evaluation of Ultradian rhythms

+improved understanding of age related changes in sleep

• sleep scientists have observed that SWS reduces with age

• The growth hormone is mostly produced during SWS therefore this is reduced in older people

• The resulting sleep deficit may explain various issues in old age

• This suggests that knowledge of the rhythms have practical value

-individual differences are ignored

• small sample, studies differences are likely to be biologically, determined

• This difficult to describe enormously in any meaningful way