Biopsychology AQA

The nervous system

Consists of CNA, peripheral nervous system + somatic

2 main functions of the nervous system

1. Collect, process + respond to info in environ
2. Coordinate working of dif organs + cells in bnody

CNS

The brain, spinal cord and origin of all complex commands + decision

The brain

The centre of all conscious awareness
Cerebral cortex covers brain
Highly dev in humans + distinguishes higher mental functions from other animals

Spinal cord

Extension of brain
Passes messages to + from brain + connect nerves to PNS
Responsible for reflex actions eg pulling hand away from hot plate

peripheral nervous system

Sends info to CNS from outside world + transmits messages from CNA to muscles + glands in body
Subdivisions: SOmatic + Autonomic

Somatic NS

Transmits info from receptor cells in sense organs to CNS and receives info from CNS that directs muscles to act
Maintains connections between CNS + outside world
governs musc movement + receives info from sensory receptor

Autonomic NS

Transmits info to + from internal bodily organs. System operates involuntarily.
Divided to: Sympathetic + parasympathetic
Important in homeostasis
Governs vital functions in body eg breathing

Endocrine system

one of bodys major info systems that instruct glands to release hormones directly to bloodstream. Hormones carried to organs communicate via chem
It works alongside nervous system to control vital functions - more slow

Gland

Organ in body synthesises substances eg hormones

Hormones

Chem substance circulate in bloodstream + only affect target organs. Produced in large quantities but disappear quick

Adrenaline

Released from adrenal gland (medulla)
Key for fight or flight

Thyroxine

Released from Thyroid
Regulates metabolism

Melatonin

Released from Pineal gland
Important for biological rhythms

Cortisol

Released from Adrenal gland
Stimulates release of glucose to provide body w/ energy while suppressing immune system

Fight or Flight

How animal responds when stressed. Body physiologically aroused in readiness to fight an aggressor or flee

Explain process of fight or flight

Endocrine + ANS work in parallel
1. When stressor perceived the hypothalamus activates pituitary glands + triggers activity in sympathetic branch
2. ANS changes from normal resting state (Parasympathetic state) to physiological aroused (Sympathetic state) back when threat has passed
3. Process is immediate + automatic

Neuron

basic building block of the nervous system, nerve cell process + transmit messages through electrical + chemical signals
100 bil in humans 80% located in brain

Explain the 3 types of neurons

1. Sensory -- carry messages from PNS to CNS where they translate impulses to sensory
2. Relay -- connect sensory to motor or relay
3. Motor -- connect CNS to effectors. Control muscle movement by releasing neurotransmitters that bind to receptors on musc leads to movement

Structure of neuron

1. Cell body (Soma) -\> contains genetic material of cell
2. Nodes of Ranvier -\> gaps in myelin sheath - elec impulse speeds up transmission down axon
3. Dendrites -\> branch-like structures protrude from cell body + carry impulses from other neurone to cell body
4. Axon -\> carries impulses away from cell body down length of neuron
5. Myelin sheath -\> layer fat covers axon protecting + speeding up transmission of elec impulses

Electrical transmission

Neuron is resting in cell - negatively charged
Neuron activated by stimulus -\> inside positive for few sec causing action potential - creates elec impulse that travels down axon to end of neuron

synaptic transmission

Process neighbouring neuron communicate w/ each other by sending them messages across synapse

Synaptic transmission process

1. Electrical impulse reaches end of neuron triggers release of neurotransmitter
2. Neurotransmitter travel across synapse (in form chem signals)
3. Neurotransmitter bind to receptor site of post-synaptic neuron
4. Chemical messages converted back to elec signal, travels down neuron

Neurotransmitter

Brain them released from synaptic vesicle that relay signals across synapse from 1 neuron to other

process of neurotransmission

Carry signal across synaptic gap it binds to receptor site on post-synaptic cell then becomes activated
When neurotransmitter is taken up by post-synaptic receptor cell, the messages r converted to elec impulse + travels down axon to next neuron
Has own molec structure that fits in post-synaptic receptor site
Eg. ACh is found at each point where motor neuron meets muscle + when released cause muscle contract
Travels one way -- neurotransmitter released from presynaptic neuron terminal + received by postsynaptic

Inhibition

Neurotransmitter increases neg charge of postsynaptic neuron. Decreases likelihood postsynaptic pass on elec impulse eg serotonin

Excitation

Neurotransmitter increases positive charge of postsynaptic increasing likelihood it passes on elec impulse eg adrenaline

Summation

Whether a postsynaptic neuron fires decided by summation
Excretory + inhibitory influences are summed - Action potential of postsynaptic neuron
Only triggered if sum of excitory + inhibitory signals at one time exceed threshold value

What is the theory of holistic brain function?

Argues that all parts of the brain are responsible for processing and functioning with no one part solely responsible for one function.

What is the theory of localised function?

Specific areas of the brain are responsible for specific processes.

What is hemispheric lateralisation?

The brain is divided into two hemispheres and each hemisphere has a specialised function. The left hemisphere controls the right side of the body and vice versa. Both composed of grey matter.

FRONTAL LOBE structure

- Contains the motor cortex, which is separated from the parietal lobe via the central sulcus (deep cleft).
- Contains Broca's area

FRONTAL LOBE function

Motor cortex is responsible for the planning and execution of movement.

FRONTAL LOBE damage

- Loss of mobility & poor motor functioning (contralateral)
- Broca's aphasia - slurred, laborious speech, lacks frequency

PARIETAL LOBE structure

Contains somatosensory cortex (at the front of the parietal lobe, just behind motor cortex)

PARIETAL LOBE function

- Somatosensory area receives sensory info from the body.
- The amount of sensory area devoted to a particular body part determines its sensitivity.
- Responsible for: touch/pressure, temperature, nociception (pain)

PARIETAL LOBE damage

Impaired sensation (contralateral)

OCCIPITAL LOBE structure

Contains visual cortex

OCCIPITAL LOBE function

Information entering eyes from left visual field is processed by right hemisphere visual cortex and vice versa.

OCCIPITAL LOBE damage

Damage to left hemisphere visual cortex will impair vision of right visual field and vice versa.

TEMPORAL LOBE structure

- Contains Wernicke's area

TEMPORAL LOBE function

- Auditory areas (analysis of speech and language).
- Left temporal lobe is dominant in language comprehension.

TEMPORAL LOBE damage

- Hearing/comprehension impairment
- Wernicke's aphasia- can speak but it is nonsensical. Introduction of unintended words or syllables

Broca's area

Small area in left frontal lobe responsible for speech (had a patient that could only say 'tan')

Wernicke's area

In the left temporal lobe; involved in language comprehension and expression

EVAL FOR THEORY OF LOCALISATION - Mental Disorder

44 people with OCD had undergone surgery, isolating an areas of the brain. After 32 weeks, 30% had had a successful response to the surgery, and 14% had a partial response. This success suggests that behaviours of certain mental disorders may be localised.

EVAL OF THEORY OF LOCALISATION- Petersen

Found that Wernicke's area was active during listening (comprehension) whereas Broca's area was active during reading (production of language). Used brain scanning. Therefore, objective methods of measuring have provided sound scientific evidence that many functions are localised.

EVAL OF THEORY OF LOCALISATION- Phineas Gage

Case study from 1823-1860. Experienced damage to left frontal lobe after a metal pole went through his head. His memory and motor function was unaffected, whereas his personality changed. Became inpatient, aggressive and selfish. Suggests that different areas of the brain are responsible for memory, motor function and aggression.

EVAL OF THEORY OF LOCALISATION- Lashley

Destroyed 10%-50% of the cerebral cortex of rats who were learning a maze. Found that no one area affected learning of the maze more than another. Suggests brain works holistically, so acts as evidence against localisation.

EVAL OF THEORY OF LOCALISATION- Trembly

Trembly found 2% of modern researchers think that language in the brain is completely controlled by Broca's area and Wernicke's area. Advances in technology have allowed the brain to be studied in more detail. Suggests, that rather than being confined to a couple of key areas, language may be organised more holistically in the brain.

Hemispheric lateralisation

Idea 2 hemispheres of brain are functionally different and certain mental processes + behaviours are mainly controlled by 1 hemisphere not the other

Outline hemispheric lateralisation

Some func appear in both hemispheres eg visual area in left and right occipital lobe in LH/RH
Language can be lateralised as its performed in LH - analyser
Visuospatial functions is RH - synthiser

What functions are not lateralised

Motor areas - cross-wired as RH controls left sides movements
Vision - contralateral + ipsilateral (same-sided) - each eye receives LVF + RVF. LVF both eyes connected to RH to enable visual areas to compare slightly dif perspective from each eye + aids depth perception

Is language lateralised in the brain?

Yes - there a two main centres in the left hemisphere, Broca's area and Wernicke's area

EVAL hemispheric lateralisation -- FINK

Used PET scans identify which brain areas active during visual processing, 'Normal' ppts asked to look at image. As a whole, RH more active, but when focussing on finer detail, LH dominated
This suggests that hemispheric lat occurs in both normal + split-brain ppl

EVAL hemispheric lateralisation -- NIELSON

Conflicting evidence on LH being analyser + RH synthesiser -- research suggests ppl dont have dominant side of brain.
Analysed brain scans from +1000 ppl ages 7-29 found ppl used certain hemispheres for certain tasks
No dominance. This suggests that the notion of right- or left-brained people is wrong.

Split-brain research

Studies involving ppl w/ epilepsy who'd experienced surgical separation of hemispheres in brain to reduce severity of symptoms
Electrical signals cannot pass over hemispheres

Sperry's research into lateralisation- 'Describe what you see'

(Corpous collosum was severed in 11 epileptic patients)
1) A word was flashed to the ppts right visual field (would be processed by left visual area)
2) Because left hemisphere is dominant in verbal processing, the patient recognises and repeats the word
3) Word is flashed to participants left visual field. Processed by right hemispehere
4) Right hemisphere cannot share info to the left for verbal processing, so patient cannot say the word they saw, but can draw with left hand, as right hemisphere controls left side of body.
5) LANGUAGE MUST BE LATERALISED TO THE LEFT HEMISPHERE

Sperry's research into lateralisation- Recognition by touch

1) Ppt is separated from a group of objects by a division.
2) An image is presented to the left visual field, so is processed by right hemisphere.
3) Info cannot cross into left hemisphere for verbalisation, so ppt cannot say what they see
4) However, they can select the object that was presented to them with their left hand, as the right hemisphere processed the information and recognised the object but couldn't verbalise it.

EVAL OF SPERRY'S RESEARCH - different degrees of disconnection

Disconnection between the hemispheres was greater in some patients than in others. This means info still could have been transmitted between hemispheres due to corpus callosum not being severed completely. Suggests that some transfer between hemispheres may have occurred as the confounding variable is introduced, reducing the internal validity of plot-brain research.

EVAL OF SPERRY'S RESEARCH- drug therapy

All participants had undergone drug therapy at some point in their lives to help treat their epilepsy. Different drug therapies and different amounts act as a confounding variable, as they may have inadvertently altered brain structure and thus affected lateralisation.
Suggests that ppts brain structures were already altered, reducing internal validity of split-brain research.

EVAL OF SPERRY'S RESEARCH- small sample size

Research relates to small sample size with unique condition. No guarantee that lateralisation in those without epilepsy works in the same way. People without epilepsy were used as a control, this acted as a major confounding variable.
Decreased population validity and meant that the unique features may have been due to epilepsy, not split brain.

How age affects functional recovery - Knoflach (2013)

A: To analyse association between age and functional recovery after stroke.
P: 14,000 patients. 2,000 were 55 y/o or younger. Analysed effect of age on functional outcome 3 months after stroke.
f: Good outcome was achieved in 88% of young stroke patients. Age emerged as strongest predictor of recovery, independent of sex, risk factors etc.

What is functional recovery?

A form of plasticity. Following damage through trauma, the brain's ability to redistribute or transfer functions usually performed by a damaged area(s) to other, undamaged area(s).

What happens in the brain during functional recovery?

1) the Brain forms new synaptic connections close to the area of damage
2) secondary neural pathways that wouldn't usually be used are activated taking over the functions of damaged areas
- Axonal sprouting
- Denervation super sensitivity
- Recruitment of homologous areas

What is axonal sprouting?

growth of new nerve endings to form new neurol pathways

What is denervation super sensitivity?

when axons that do similar jobs become aroused to a higher level to compensate for ones that are lost
- however, this can have a negative consequence of over sensitivity of messages such as pain.

What is the recruitment of homologous areas?

Regions on opposite sides of the brain take on functions of damaged areas.

What is brain plasticity?

The brain's tendency to change and adapt as a result of learning and experience, involves the growth of new connections

Maguire et al (2000) (brain plasticity)

P: conducted MRI scans of black cab drivers. 16 male London taxi drivers were included. Control of 50 healthy males were included for comparison.
F: A) Increased grey matter was found in brains of taxi drivers in both left and right hippocampi
B) Correlation (+0.6) was found between amount of time spent as taxi drivers and the volume in right posterior hippocampus. Hippocampus is involved in spatial memory.

EVAL OF MAGUIRE - predisposition

Retrospective study. May be that individuals with larger hippocampi have naturally better memory, so are predisposed to be in that type of job (taxi drivers)

EVAL OF MAGUIRE- evidence against predispostition

The volume of the drivers' posterior hippocampus increased (learning), so volume of anterior hippocampus decreased (synaptic pruning). Supports brain plasticity as brain adapts as new information is learned.

EVAL OF BRAIN PLASTICITY- negative plasticity

Plasticity can have maladaptive behavioural consequences. eg. phantom leg syndrome in 60-80% of amputees due to cortical reorganisation in somatosensory cortex. Plasticity is not always beneficial after injury and further research needs to be collated.

EVAL OF BRAIN PLASTICITY - age and plasticity

It may be a lifelong ability, in general it reduces with age, but (Bezzola) found that after 40 hours of golf training the neural representations of movement in ppts aged 40-60 had changed. Using fMRI.
Suggests plasticity can continue throughout the lifespan.

EVAL functional recovery -- Schneider, cognitive reserve

Socially sensitive - Schneider said levels of education can influence recovery rate.
More time in education \= greater chance of disability free recovery. 40% achieved this had spent +16 yrs in education + 10% had spent less than 12 yrs
Large disadvantage to ppl who cannot access education

What are the four ways of studying the brain?

fMRI, EEG, ERP, post-mortem

Post-mortem description

- Brain is studied after death. Involved dissection
-Individuals who suffered rare disorders or atypical disorders often undergo post-mortem
-Areas of the 'neuroatypical' brain are compared to a neurotypical brain. Helps with localisation of function.
- Correlate structural abilities to behavioural change

strengths of post-mortem examinations

-Anatomical structures can be studied in depth using microscopy- not possible with brain scans.
-Can study deeper regions of the brain such as hypothalamus- not possible with brain scans
-Real world application as Broca and Wernicke both relied on post-mortem to establish links within the brain
-Also used to study HM's brain and identify areas of damage

Weaknesses of post-mortem

- Lack of external validity due to small sample sizes. Issues with generalisation.
- Issues of causation- impairment suffered may not originate from the brain. Cannot establish the brain as a cause of abnormal behaviour as unable to test after death.
-Ethical issues, consent must be obtained from ppt before death

fMRI description

- Detects changes in blood flow in the brain. When performing functions the area of the brain responsible required more oxygen, so increased blood flow (haemodynamic response)
- Activation maps are created. Helps with localisation of function.
- Creates a 3D, moving image of brain
- Activity in regions can be compared between specific activity + baseline tasks

Strengths of fMRI

- non-invasive unlike other techniques, as does not use radiation or inserting instruments.
- Greater sample size due to lack of risk. Aids gathering of further detail on functioning of human brain.
-Produces images with very high spatial resolution, providing clear pictures of localisation

Weaknesses of fMRI

- Poor temporal resolution. This because there is a long process before oxygen is detected (stimulus detected, activation, blood flow increase). (approx 4 secs compared to EEG)
-Can show localisation of function but not communication, which could be crucial to neural functioning.
-It is expensive in comparison with other neuroimaging techniques

EEG description

- detects electrical activity from neurons in the brain
- Electrodes are placed on scalp, and electrical charges are detected and graphed over a period of time detect activity directly below
- Amplitude \= intensity of activity, Frequency\= the speed/quantity of activity.
- Diagnose epilepsy/ tumours/ sleep disorders

Strengths of EEG

- Good temporal resolution- detects changes in electrical activity up to a millisecond.
- Direct measure of brain activity as detects electrical signal (unlike fMRI, which is an indirect measurement)
-Been useful in studying the stages of sleep and for disease diagnosis

Weaknesses of EEG

- Poor spatial resolution - each electrode can only detect electrical impulses under its surface. Poor localisation of cortical function. Generalised nature of the information received.
- Only detects brain activity in outer brain regions so not very useful for study of internal brain activity.

ERP description

- uses EEG equipment but key difference is that stimulus is presented, and researcher looks for activity related to that stimulus. - allows researcher to isolate responses
- All extraneous brain activity is filtered out leaving only neuronal activity present at the time of the production of the stimulus.
- Response to stimulus from researcher

Strength ERP

- Specific measurement of neural activity - precise reading of localisation
- Excellent temporal resolution

Limitations ERP

- Lack standardisation in ERP methodology
- Establish pure data - background noise + extraneous materials eliminated - not easy to achieve

What is a circadian rhythm?

- Occurs once every 24 hours
- Regulated by endogenous pacemakes and exogenous zeitgebers
- regulates body processes such as the sleep/wake cycle and changes in body temperature

What is an endogenous pacemaker?

An internal biological clock. Each cell has its own biological clock but they are all kept in sync by the suprachiasmatic nucleus

What is an exogenous zeitgeber?

External cues that regulate a circadian rhythm (eg. light, social cues)

Example of circadian rhythm

Sleep/wake cycle (daylight \= exogenous zeitgeber)

Research into sleep/wake cycle - SIFFRE'S CAVE STUDY PROCEDURE

A: To study the effects of lack of exogenous zeitgebers on endogenous pacemaker and sleep/wake cycle

P: Isolated himself within a cave for 2 months. No natural light or sounds so no clues as to what time it was (exogenous zeitgeber)

Research into sleep/wake cycle; SIFFRE'S CAVE STUDY FINDINGS

F: 'Free-running biological rhythm settled down to one that was just beyond the usual 24 hours (25 hrs). Continued to wake up and fall asleep on a regular schedule.

Eval- SIFFRE'S CAVE STUDY

- one ppt study - lacks population validity and difficult to generalise to the rest of the population
- poor control- turned light on each time he woke up until he went to bed. Assumes artificial light had no affect on 'free-running' biological clock. H/e, Czeisler managed to alter the sleep/wake cycle of ppts from 22hrs to 28hrs using dim lighting.

Research into sleep/wake cycle- ASCHOFF'S BUNKER STUDY PROCEDURE

P: group of ppts spent 4 weeks in underground bunker. All were students and were allowed to study for exams. Deprived of natural lights

Research into sleep/wake cycle- ASCHOFF'S BUNKER STUDY FINDINGS

F: All but one ppt displayed sleep/ wake cycle between 24-25 hrs. (His extended to 29h)
Suggests natural sleep/wake cycle is slightly longer than 24 hours, influenced by EZ

Eval of Aschoff's bunker study

- \= low mundane realism- spent most of time revising resulting in a low sleep load. May explain short sleep/wake cycle
+ large sample size

Research into sleep/wake cycle- FOLKARD'S CLOCK EXPERIMENT PROCEDURE

P: studied a group of 12 people who stayed in a dark cave for 3 weeks. Went to be at 11:45 pm and woke at 7:45am. Over the course of the study, the researchers gradually speeded up the clock to a 22hr cycle

Research into slee/wake cycle- FOLKARD'S CLOCK EXPERIMENT FINDINGS

F: Only one of the ppts adapted to new schedule. Suggests existence of a free-running circadian rhythm that cannot easily be overriden by exogenous zeitgebers.