everything

What is Nervous System?

It’s a network of cells which has two important functions

1) Collect info from the world and process it

2) Direct body organs and muscles using electric/ chemical signals

It splits into 2 sub-systems (PNS and CNS)

What is Central Nervous System?

1) Controls behaviour

2) Regulates the body’s physiological processes

What is brain (CNS)?

-It’s divided into two hemispheres

-Centre of all conscious awareness

-Has an outer layer cerebral cortex (3 mm thick) and only found in mammals

What is spinal cord (CNS)?

-Passes messages between brain and body

-Connects brain to the peripheral nervous system (PNS) via spinal nerves

-Controls reflexes (fast, automatic responses)

What is Peripheral Nervous System (PNS)?

A body wide network of neurones that transmits info to and from CNS to the rest of the body.

-Sensory Neurones carry info from receptor TO the CNS

-Motor Neurones transmit signals AWAY from CNS to muscles/glands

What is Autonomic Nervous System (PNS)?

-Controls internal organs and glands (breathing, heart rate). Therefore is involuntary system(not under control).

-Only has motor pathways

-Controls smooth muscles and glands

What is Somatic Nervous System (PNS)?

-Controls skeletal muscles for movement

-Has motor pathways (carry signals from brain to skeletal muscles). Therefore is under conscious control

-Has sensory pathways (transmits info from sensory receptor to brain/CNS)

What is Sympathetic Nervous System (ANS)?

-Activates a stress response (fight or flight) and releases adrenaline and noradrenaline (heart rate increases, breathing rate increases)

What is Parasympathetic Nervous System (ANS)?

-Activates in rest (rest and digest), decreases body activities (heart rate decreases, breathing rate decreases)

What is endocrine system?

A system of glands which release hormones into the bloodstream. Hormones act as a chemical messengers- circulate in the bloodstream and affect target organs. It regulates processes such as growth, metabolism and mood.

What is the main gland?

Pituitary gland.

-Located in the brain

-Controls the release of hormones from all other endocrine glands in the body

-Controlled by hypothalamus

-Releases hormones like Luteinising Hormone and Follicle Stimulating Hormone

-Stimulates ovaries to produce oestrogen; testes to produce testosterone and sperm

Pineal gland

Releases melatonin, responsible for important biological rhythms, including control of sleep/wake cycle

Adrenal gland

Releases adrenaline and noradrenaline, controls sympathetic division, important in flight or fight response

Ovaries

Releases oestrogen, controls female reproductive system + menstrual cycle

Testes

Releases testosterone, controls male sex characteristics + sperm production

How fight or flight works

1) Stressor is perceived

2) Hypothalamus activates the sympathetic NS

3) ANS switches from parasympathetic (rest) —> sympathetic (aroused)

4) Sympathetic NS activates adrenal medulla, which releases adrenaline to the bloodstream

5) Physiological changes happen (high heart rate, breathing and blood pressure; digestion stops). Body is ready for fight or flight. ( this response is automatic, happens really quickly)

After the danger

6) Parasympathetic NS takes over, brings body back to normal ( hear rate decrease, blood pressure drops). “Rest and digest” response, returns body to homeostasis.

Sympathetic vs Parasympathetic (Fight and flight)

Sympathetic state (fight or flight)	Parasympathetic state (rest and digest)
Increases heart rate	Decreases heart rate
Increases breathing rate	Decreases breathing rate
Dilates pupils	Constricts pupils
Inhibits digestion	Stimulates digestion
Inhibits saliva production	Stimulates saliva production
Contracts rectum	Relaxes rectum

Evaluations for fight or flight

Gender bias

Ev: Researcher found that fight or flight is a typical male response, when females are more likely to show a “tend and befriend” response. Ex: Woman tend to protect offspring “tend” and seek social support “befriend” rather than fight or flight. So original theory is based on mainly male behaviour and ignores female responses. L: Low generalisability, as theory can’t be applied to females.

Maladaptive in Modern day Society

Ev: Modern stressors (work, exams) repeatedly trigger fight and flight response, which can have a negative impact on our health- including blood pressure and risk of heart disease. Ex: Unlike our ancestors facing real threats, today’s stress is constant and not life-threatening, so the repeated activation harms health instead of helping survival. L: Low external validity, as responses don’t reflect how people typically deal either stress in modern everyday situations.

Freeze Response

Ev: Researcher suggested that our first response to danger is to avoid confrontation altogether, shown as a freeze response. Ex: It allows individuals to become hyper-vigilant and assess the situation before deciding whether to fight or flight. L: Low internal validity, as theory doesn’t fully explain the true sequence of responses to threat.

1. Structure of neuron

A neuron is specialised cell that transmits electrical impulses.

1.The cell body (soma)- process info, contains nucleus

2.Nucleus- controls cell activity(genetic material)

3.Dendrites- carry nerve impulses from neighbouring neurons towards body cell, down the length of the neuron

4.Axon- carries electrical impulse away from the cell body

5.Myelin Sheath- fatty layer that protects axon, speeds up transmission

6.Nodes of Ranvier- gap between the myelin sheath, help speed transmission (impulses have to “jump” the gap)

7.Terminal button- at the end of the axon where neurotransmitter are released (communicate with a next neurone in the neurone chain, across the synapse)

8.Synapse- gap between neurons

Types of neurone

Sensory Neuron:

-carries impulses from receptor—> CNS

-located in PNS (cell body in ganglia)

-long dendrites, short axon

Relay Neuron:

-connects neurons with CNS(middleman doing decision-making)

-found in brain and spinal cord

-short dendrites, short axon

Motor Neuron:

-carries impulses from CNS—> effector (muscles/glands)

-located in CNS( brain, spinal cord), but long axons form part in PNS

-short dendrites, long axon

The Reflect Arc

It’s a rapid, automatic response to a stimulus.

Stimulus(hammer hits the knee) → detected by sense organs in PNS →which convey message along a sensory neuron → message reaches CNS (where it connects with relay neurone) → this then transfers message to a motor neuron → carries message to effector(muscle, which causes it to contract) → response(knee has moved)

Electrical Activity in a Neuron (firing)

1) At rest, neuron is negatively charged

2) When stimulated—> becomes positively charged (depolarisation), which causes action potential(electrical impulses) to occur

3) Impulses travel along the axon toward the end of the neurone where synaptic transmission occurs

Synaptic Transmission

1.Action potential occurs-causing depolarisation as the electric impulses travel along the presynaptic neuron

2.Presynaptic Neuron- electrical impulses reach the terminal button, where voltage-gated calcium ion channel open

3.Synaptic vesicles- vesicles containing neurotransmitters move toward the presynaptic membrane

4.Action potential reaches vesicles- vesicles fuse with membrane and release neurotransmitters by exocytosis

5.Neurotransmitters- diffuse across the synaptic gap (cleft)

6.Binding to a postsynaptic receptor- once neurotransmitters crossed the gap, they bind to specific receptor on postsynaptic neuron (lock-and-key)

7.Conversion- that caused depolarisation of the postsynaptic neuron, generating new action potential if threshold is reached

8.Reuptake- neurotransmitters are removed by reuptake or enzymatic breakdown

One way transmission

Info only travels in one direction because:

-Neurotransmitters are released only from presynaptic neuron

-Receptors are only on postsynaptic neuron

Excitation neurotransmitters

Excitation (adrenaline)

→ they increase the positive charge of the post-synaptic neuron → this makes it MORE likely that this neuron will pass on the electrical impulse.

Inhibition neurotransmitters

Inhibition (serotonin)

→ they increase the negative charge of the post-synaptic neuron → this makes it LESS likely that this neuron will pass on the electrical impulse

Summation process

Summation decides whether the postsynaptic neuron is going to pass on the electrical impulses.

The excitatory and inhibitory effects are summed:

• if the net effect on the postsynaptic neuron is inhibitory, it is less likely to fire.

• If the net effect is excitatory then it is more likely to fire (passes on the electrical impulse down the neuron)

fMRI (Functional Magnetic Resonance Imaging)

It’s a method used to measure brain activity while person is performing a task.

Measures: changes in blood oxygenation and blood flow.

Works: when a brain area becomes active, it requires more oxygen, which creates a haemodynamic response, where blood flow increases to the active brain area. The scanner detects these changes in blood oxygenation and blood flow.

Produces: 3D images (brain maps) showing which brain areas are involved in a particular mental process.

EEG (Electroencephalogram)

A method used to record electrical, activity in the brain.

Measures: Brainwave patterns produced by the activity of thousands of neurons.

Works: Electrodes are attached to the scalp. The electrodes record electrical activity generated by the brain.

Used for: can identify patterns of activity associated with epilepsy, sleep disorders

ERP (Event related potentials)

A technique derived from EEG recordings.

Measures: specific brain responses linked to a particular sensory, cognitive or motor event.

Works: researchers use statistical averaging to isolate responses related to a specific stimulus or task. This removes background brain activity and leaves only the neural response to the event.

Used for: to investigate cognitive processes.

Postmortem

Examinations of the brain after death.

Investigating: the relationship between brain structure and behaviour.

Works: researchers analyse the brains of individuals who experience cognitive, behavioural or neurological abnormalities during their lifetime. Areas of damage or abnormality are identified and linked to observed behaviour.

Useful: as allows researchers to investigate brain structures that can’t be examined in living pp.

Spatial resolution (evaluation)

-accuracy of identifying the exact location of neural activity within the brain

fMRI: +, as it has spatial resolution of approximately 1-2 mm and can detect activity in very small brain regions. So psychologists can accurately identify which specific brain areas are active during a task or behaviour, leading to more accurate conclusions about localisation of function.

EEG/ERP: -, as records activity from superficial/general regions of the brain through electrodes attached to the scalp. This means that the scanner only measures activity from the outer layer of the brain and can’t accurately identify the precise sources of neural activity, so conclusions about localisation of function are less accurate.

Temporal resolution (evaluation)

-refers to the accuracy of identifying the timing of neural activity.

fMRI: -, as scans produce an image approximately every 1-4 sec, which means that there is a delay between neural activity and image produced. So psychologists are less ble to identify the precise timing of neural activity, reducing the accuracy of conclusions about when brain processes occur.

EEG/ERP: +, as records every 1-10 seconds, which allows psychologists to measure brain activity in real time, rather than looking at a passive brain. So more accurate conclusions can be drawn about the timing of neural processes.

Invasive vs Non-Invasive (evaluation)

fMRI: +, as non-invasive and doesn’t require instruments to be inserted into the brain. Pp experience very little physical risk or discomfort, which makes procedure safer and more ethical than invasive techniques.

EGG/ERP: +, as electrodes are attached to the scalp rather than inserted into the brain, so non-invasive. The procedure is virtually risk-free and can be used safely with a wide range of pp.

Causation (evidence)

fMRI: -, as doesn’t directly measure neural activity, instead, it measures changes in blood oxygenation and blood flow. Because blood flow is only associated with neural activity, psychologists can’t be certain that observed brain activity caused a particular behav. So cause and effect conclusions can’t be established.

EGG: -, as electrical activity is often detected across several brain regions simultaneously. Researchers can’t always identify the exact region responsible for the activity, so it’s is difficult to establish cause and effect relationship between a specific brain area and behav.

ERP: +, as involves presenting a specific stimulus and statistically averaging responses to remove background noise. As neural responses can be linked directly to a known stimulus, psychologists can’t make stronger causal inferences about how particular cognitive processes are affected by experimental manipulations.

Postmortem: -, as researchers identify abnormalities after death and attempt to link them to behav shown during life. The observer deficit may not have been caused by the damaged area. Other illnesses, trauma may also have contributed, so causation can’t be firmly established.

What is Localisation?

the theory that specific areas of the brain are associated with particular physical and psychological functions.

(If an areas of the brain is damaged through illness or injury, the function associated with that area is also affected)

What is Lateralisation?

The dominance of one hemisphere of the brain for particular physical and psychological functions.

(Brocas and Wernickes ares, that are only found in the LH)

5 areas of brain that are localised?

• Visual cortex

• Auditory cortex

• Motor cortex

• Somatosensory cortex

• Language areas (Brocas and Wernickes)

Motor cortex

Location: at the back of the frontal lobe, in both LH and RH

Function: controls voluntary movement and regulates mood (left side of the body is controlled by right frontal lobe and vice versa)

Damage: loss of movement, paralysis (if damage RH, loss of movement in the left side of the body and vice versa), damage to specifically Left frontal lobe→ Brocas aphasia (difficulty with speech production)

Somatosensory cortex

Location: at the front of the parietal lobe, separated from the motor area by the central sulcus

Functions: processes sensory info from the skin(touch, heat, pressure

Additional: the amount of somatosensory ares devoted to a body part reflects its sensitivity. Hands and face occupy a large proportion because they contain many sensory receptors.

Visual cortex

Location: occipital lobe

Functions: processes visual info (each eye sends info from the RVF to the left visual cortex and vice versa)

Damage: damage to the LH can produce blindness in part of the RVF in both eyes

Auditory cortex

Location: temporal lobe

Functions: analyses speech-based info

Damage: may produce partial hearing loss( depends how extensive the damage is), damage to the left temporal lobe causes Wernickes aphasia (fluent, but nonsense speech)

Broca’s area (language area)

Location: localised to the Left frontal lobe, therefore lateralised (only left frontal lobe is responsible for this function)

Functions: responsible for speech production and enables speech to be fluent

Damage: damage to the Left frontal lobe can lead to Brocas aphasia (slow speech, difficulty with producing speech, especially with connecting words “it” and “the”)

Wernicke’s area (language area)

Location: localised to the left temporal lobe, therefore lateralised (only left temporal lobe responsible for this function)

Functions: responsible for language comprehension and enables speech to be meaningful

Damage: damage leads to Wernickes aphasia (people produce nonsensical speech and nonsense words)

Evaluations (Localisation of function in the brain)

Support from case study

Ev: The case of Phineas Gage showed that damage to the frontal lobe changed his personality from calm to someone who was rude and aggressive. Ex: shows that certain functions can be localised to particular areas of the brain. Damage to frontal lobe showed changes in personality, suggests that personality and behaviour are associated with specific areas of the brain, particularly the frontal lobe. L: High internal validity, as supports the idea that specific functions are localised to particular brain areas.

Cognitive functions are distributed more holistically across the brain

Ev: Research has removed between 10% and 50% of the prefrontal cortex in rats that were learning route through maze. No area was shown to be more important in terms of the rats LTM ability to learn the route. Ex: suggests that memory may not be localised to one specific brain area and instead may involve several regions working together. L: questions internal validity, as functions may not be controlled by a single localised area.

Contradictory research

Ev: Research scanned the brain of Brocas patients with MRI scanning. He found that other areas of the brain could have also contributed to the patients reduced speech abilities. Ex: Suggests that language production may involve several interconnected brain regions, rather than just Broca’s area. Damage to one area doesn’t always produce the same symptoms in every patient. L: low reliability, as findings don’t consistently show that one specific brain area is solely responsible for a particular function

Motor areas are contralateral

Contralateral= cross-wired

-LH controls the right side of the body

-RH controls the left side of the body

Visual fields are also contralateral

Info from the left side of both eyes travels to the RH.—> LVF is processed by the RH.

Info from the right side of both eyes travels to the LH.—> RVF is processed by the LH

Why can’t we say that visual fields are lateralised?

We can’t say “motor areas are lateralised”, as both hemispheres have motor cortices. However, we can say “processing of the LVF is lateralised to the RH, as only the RH processes info from the LVF.

What is Corpus Callosum?

A thin piece of tissue connecting the two hemispheres. (Function: allows L and R hemispheres to communicate)

What is Split brain patients?

A person whose corpus callosum has been cut, so two hemispheres can’t communicate with each other. Done to reduce epileptic fits.

Sperry Split-Brain Research: Speech

Procedure: 11 split brain individuals were studied. Image was projected to the LVF (processed by RH), patients were asked to verbalise what they saw. Procedure repeated for the RVF.

Findings: When object was shown to their LVF (processed by RH), they couldn’t name object.

When object was shown to their RVF (processed by the LH), they could verbally describe object

Explanation: because info in LVF is processed by RH, where there is no language centres. And as corpus callosum is cut, info can’t reach LH language centres, so patients can’t verbalise what they saw. And info in RVF is processed by the LH where the language centres are, so they can verbalise what they saw.

Sperry split-brain research: Tactile/touch/draw

Procedure: objects show to the LVF (processed by the RH), pp were asked to verbalise what objects were shown and also asked to select a matching object using left hand or draw the object with left hand.

Findings: pp could name them (as processed by RH which doesn’t have language centres), but could select a matching object using left hand/could draw object using left hand.

Explanation: cause info shown in LVF is going to RH which controls left side of the body, RH can “understand” what the object was and select/ draw it with left hand. (RH just can’t verbalise it)

Evaluations ( split brain reader h into hemispheric lateralisation)

Research support

Ev: research carried out further investigation with split-brain patients and found that the two hemispheres have different but complementary functions. LH was better at language processing, whereas the RH was better at visual-spatial tasks. Ex: findings replicate the Sperrys original research, demonstrating consistency across studies. L: high reliability, as similar findings have been repeatedly obtained.

Confounding variables

Ev: Sperrys split-brain patients were compared to a neurotypical control group, but all of the patients had severe epilepsy and had undergone surgery to sever the corpus callosum. Ex: makes it difficult to determine whether the differences found were caused by severing the corpus callosum or by the long-term effects of epilepsy itself. L: cause and effect relationships cannot be established, reducing the internal validity.

Lacks mundane realism

Ev: pp were required to stare at a fixed point while images were flashed briefly to one visual field, which is not how people normally process info in everyday life. Ex: the tasks were highly artificial and don’t reflect how the hemispheres operate during normal behaviour. L: findings may not generalise to real-world situations, reducing the external validity.

Plasticity

The brain ability to adapt both its function and structure due to changes in the environment. Changes in the environment include:

-learning new skills

-developmental changes

-brain injury (direct=to a specific area of the brain, indirect=damage such as brain bleeding from a stroke)

AO1 Plasticity

Neurones and Synapses

Brain is made up of neurones, they are connected by synapses, so info travels between neurones across synapses. As info passes through the brain, new neuronal pathways are formed.

Synaptic Connection in Childhood

During infancy, the number of synaptic connections increases rapidly, peaking at about 15,000 per neurone at 2-3 years old (twice as many as in adult brain).

Synaptic Pruning

As we go older, we go through the process called synaptic pruning. During it: weak and rarely used connections are deleted, strong and frequently used connections become stronger.

Maguire (2000) London Taxi Drivers

Aim: to investigate whether experience changes brain structure.

Procedure: Maguire used brain scans to compare post hippocampus of London taxi drivers and a controlled group of non taxi drivers. Taxi drivers have to learn large amounts of route info.

Findings: taxi drivers had a larger post hippocampus, in comparison to the controlled group.

Explanation: the positive correlation of the structure difference show plasticity, as the brain is able to adapt and change to the environment, in this case to improve memory formation.

Evaluations (Plasticity)

Age and Plasticity(plasticity is a lifelong ability rather than something that only occurs in childhood)

Ev: Research found that 40 hours of golf training, pp age 40-60 showed increased activation in the motor cortex, demonstrating that the brain continued to modify its neural connections and adapt in response to experience, despite the pp being well beyond childhood. Ex: shows that brain remains capable of reorganising itself and forming neural pathways throughout the lifespan, so plasticity is not limited to early development and can occur in adulthood when individuals learn new skills.

Negative plasticity (brains ability to adapt in not always beneficial)

Ev: Brain adapts to the environment, which means it adapts to prolonged drug use. Research found that the brain adaptation to drug use leads to poorer cognitive function and an increased risk of dementia. Ex: challenges the view that plasticity is always advantageous because the changes that occur may have negative consequences for cognitive functioning.

Research support (experience can physically alter the structure of the brain)

Ev: Maguire used MRI scans to compare the brains of London taxi drivers with non taxi drivers. They found that taxi drivers had a larger posterior hippocampus and that the size of this ares positively correlated with a number of years spent working as a taxi driver. Ex: demonstrates that repeated experience and environmental demands can lead to structural changes in the brain. So brain is capable of adapting and recognising itself in response to learning and experience.

Functional Recovery (AO1)

-It’s the brain ability to redistribute or transfer functions that were previously carried out by damaged brain areas to other undamaged areas (functional reorganisation). Functions that were performed by the damaged area are taken over by healthier areas of the brain.

-Function recovery happens quickly after trauma (spontaneous recovery) and then slows down after several weeks or months. During this period, the brain reorganises and rewires itself to compensate for damaged areas.

Mechanisms of Functional Recovery:

1. Atonal sprouting- the growth of new nerve endings which connect with other undamaged neurons to form new neural pathways. When an injury damages an existing neural pathway, new connections grow from surviving neurones. These pathways allow communication to continue despite the damage.

2. Denervation Supersensitivity- when neurons lose some of their incoming connections, the remaining axons become more sensitive. The surviving neurones become more likely to fire in response to stimulation, which compensates for the loss of neurons in the damaged pathways. (negative consequences= oversensitivity to messages such as pain)

3. Recruitment of homologous areas- the opposite hemisphere takes over functions previously performed by the damaged area. A homologous area on the other side of the brain carries out the lost function. (If Broca’s area in the LH is damaged, the RH equivalent may take over speech production. After recovery, functioning may gradually shift back to the original hemisphere).

Factors that make functional recovery more likely (AO1)

-Age. Children show the greatest ability to recover. Adults can recover too, but generally less effectively.

-Gender. Women appear to recover more successfully from brain damage than men.

-Rehabilitation Therapy. Focused rehabilitation and practice improvement recovery outcomes. Recovery is more successful when patients actively engage in therapy

Evaluations (Functional Recovery)

Supporting evidence

Ev: Patient EB underwent a LH at the age of 2,5 which involved the removal of both language areas (Broca and Wernickes). Despite this, over a two year recovery period regained almost full language functioning. fMRI scans showed that language functions had been transferred to the RH. Ex: supports functional recovery, as it shows the recruitment of homologous areas. The RH equivalent of the language areas took over the functions previously carried out by the damaged LH. So findings support the idea that the brain can reorganise itself and redistribute functions following trauma.

Real world example

Ev: research has improved psychologists understanding of how the brain recovers following injury and has led to the development of rehabilitation programmes designed to promote recovery. Ex: knowledge can be applied to help patients recover from strokes, brain injuries. Understanding processes like functional recovery and atonal sprouting allows therapists to develop more effective rehabilitation techniques, improving patients quality of life and increasing the practical value of the research.

Evidence that recovery is influenced by age

Ev: research suggests that children show the greatest capacity for functional recovery following brain injury, whereas recovery become less effects with increasing age. Ex: demonstrates that brain retains the ability to reorganise itself after damage. The greater recovery shown by younger individuals suggests that neural plasticity and functional reorganisation are particularly effective early in life. Findings provide support for the brains ability to adapt following trauma.