Biopsychology

Which four parts is the brain divided into?

cerebrum, cerebellum, diencephalon and brain stem

Which four lobes is the cerebrum divided into?

frontal, temporal, parietal and occipital

Frontal lobe function

thought and production of speech

occipital lobe function

processes visual info.

temporal lobe function

processes auditory info.

parietal lobe function

processes sensory info. and plays an important role in spatial navigation

cerebellum function

motor skills and balance

which two structures is the diencephalon split into

the thalamus and the hypothalamus

thalamus function

relays nerve impulses from senses to appropriate parts of the brain where they can be processed

hypothalamus function

homeostasis and controls the release of hormones from the pituitary gland

brain stem function

regulates automatic functions

which NS is split into the Sympathetic NS and Parasympathetic NS

autonomic

somatic NS function

responsible for voluntary actions. maintains communication between CNS AND PNS using 12 pairs of cranial nerves and 31 pairs of spinal nerves

autonomic NS function

important in regulating actions over which you have no conscious control (like homeostasis)

sympathetic NS function

prepares the body for fight or flight via the use of the stimulating transmitter, noradrenaline

parasympathetic NS function

returns the body to its resting state after the fight or flight response via the use of the neurotransmitter, acetylcholine

evaluate theories of the “fight or flight” response

• gender bias (androcentrism) - Early research into stress used only male animals and found the “fight or flight” response. Later research showed that females often respond with “tend and befriend” — showing that gender differences were overlooked. This is beta bias.

  • If our understanding of 'normal' behaviour comes from research involving all-male samples, then any behaviour that deviates from this standard is classed as 'abnormal' or 'inferior'.

  • This leads to female behaviour being misunderstood and even pathologised (taken as a sign of illness).

• Von Dawans found that men can also respond with friendly and cooperative behaviour (e.g during 9/11)

sensory neurons (what they look like and function)

they are attached to a receptor cell and they are responsible for carrying impulses to CNS

relay neurons (what they look like and function)

they don't have a myelin sheath and they allow sensory and motor neurons to communicate. They lie within the CNS

motor neurons (what they look like and function)

they control muscles and they release neurotransmitters that bind to the receptors on muscles to trigger a muscle contraction.

Muscle relaxation is caused by inhibition of the motor neuron

dendrites function

receive signals from other neurons

axon function

a long fibre that carries impulses also known as an action potential

myelin sheath function

insulates the axon so that impulses travel faster

synaptic vesicles function and location (in neuron)

these are located at the end of the axon and they contain neurotransmitters

the action potential reaches vesicles and causes them to release neurotransmitters through a process called exocytosis

axon terminal function

connects the neuron to others using a process called synaptic transmission

when does excitation in the postsynaptic neuron occur?

receptor stimulation results in an increase in the positive charge of the postsynaptic neuron and increases the likelihood of the neuron passing on the impulse

when does inhibition occur in the postsynaptic neuron?

receptor stimulation results in the increase in the negative charge of the postsynaptic neuron and decreases the likelihood of the neuron passing on the impulse

what is ‘re-uptake’ in synaptic transmission?

the remaining neurotransmitters after transmission are broken down and reabsorbed by the presynaptic neuron and stored for later use

types of neurotransmitters

• Dopamine - attention, learning

• Acetylcholine - memory, learning

• Noradrenaline - ‘fight or flight’

• Serotonin - emotion, sleeping

• GABA - fear, anxiety

what is summation?

the addition of EPSPs and IPSPs

how is a synapse unidirectional?

receptors only on postsynaptic neuron and neurotransmitters only released from presynaptic

what is spatial summation?

several presynaptic neurons can combine to cause an action potential in a postsynaptic neuron

what is temporal summation?

several action potentials produce synaptic transmissions in order to produce a postsynaptic action potential

what is divergence? (synaptic transmission)

impulses from one presynaptic neuron can be passed to several postsynaptic neurons

the entire process of synaptic transmission

action potential → axon terminal + vesicles → exocytosis → diffuse and bind to specific receptors → summation → reuptake (An ATV Enters DuBai So Rapidly)

As the action potential reaches the synaptic vesicles and the axon terminal, it causes the vesicles to release neurotransmitters as part of a process called exocytosis. These neurotransmitters diffuse across the synaptic gap (down a concentration gradient) where they bind to SPECIFIC receptors on the dendrite of the post-synaptic neuron.

Depending on the neurotransmitter, there is either an excitatory or inhibitory effect on the firing of the next action potential. The effects are then terminated by a process called re-uptake, where the remaining neurotransmitters are broken down and reabsorbed by the presynaptic neuron.

what is something that stimulates ‘fight or flight’ called?

a stressor

fight or flight process (6 steps)

1. person enters a stressful situation

2. the amygdala sends a distress signal to the hypothalamus

3. hypothalamus activates SAM pathway

4. the sympathetic NS stimulates the adrenal medulla

5. adrenal medulla secretes adrenaline + noradrenaline into bloodstream

6. physiological changes occur to prepare body

why might females have a “tend and befriend” response instead? what causes it?

this might be due to a need to protect offspring from predators.

females have oestrogen, which increases oxytocin levels, resulting in a reduced stress response

pituitary gland function

it stimulates the release of hormones from other glands

what is the pituitary gland divided into?

anterior and posterior lobes

what does the anterior lobe in the pituitary gland release? what is this hormone for?

ACTH, which stimulates the adrenal cortex and the release of cortisol. cortisol manages long-term stress

what does the posterior lobe in the pituitary gland release? what is this hormone for?

oxytocin - responsible for uterus contractions during childbirth

what does the pineal gland release? what is this hormone for?

melatonin - responsible for biological rhythms

what does the thyroid gland release? what is this hormone for?

thyroxine - responsible for regulating metabolism

what is hyperthyroidism?

too much thyroxine (skinny)

what is hypothyroidism?

too little thyroxine (fat)

what is the adrenal gland divided into? what do they do?

adrenal medulla - releases adrenaline and noradrenaline which are used in fight or flight

adrenal cortex - releases cortisol which stimulates glucose release

what do the testes release? what is this hormone for?

testosterone - responsible for development of secondary male sex characteristics during puberty

what do the ovaries release? what is this hormone for?

oestrogen - involved in the regulation of the menstrual cycle and development of secondary female sexual characteristics

what are the SAM and HPA systems?

SAM pathway - immediate shock response

HPA axis - countershock response

where is the motor centre located and what does it do?

it is located in the frontal lobe and is responsible for voluntary movements by sending signals to muscles

where is the somatosensory centre located and what does it do?

it is located in the parietal lobe and receieves incoming sensory info from the skin to produce sensations.

where is the visual centre located, what does it do and how does it work?

it is located in the occipital lobe and processes colour, shape and movement.

processing starts in the retina →optic nerve → thalamus → visual cortex

where is the auditory centre located, what does it do and how does it work?

it is located in the temporal lobe and it processes acoustic information like volume, tempo and pitch.

pathways begin at the cochlea (soundwaves converted to nerve impulses) and then the brain stem (basic decoding e.g. intensity/duration) before reaching the auditory cortex where a response is initiated.

where is broca's area and what does it do?

it is located in the left frontal lobe and is responsible for speech production

where is wernicke's area and what does it do?

it is located in the left temporal lobe and is responsible for language comprehension

support for localisation of function from case studies

Phineas Gage suffered damage to the frontal lobe and as a result his mood + personality changed.

indicates that frontal lobe is responsible for these

support for localisation of function from brain scanning studies

Peterson used brain scans to show how Wernicke's area was active during a listening task and how Broca's was active during a reading task.

brain scans are an objective and scientific way of showing localisation of function

support for localisation of function from neurosurgery procedures

Dougherty showed that procedures like the cingulotomy is successful with OCD patients. this involves damaging the cingulate gyrus

evidence against localisation of function due to no localisation of higher order functions

Lashley showed that learning was not localised to one specific area.

this suggests that higher order functions are dealt with more holistically.

evidence against localisation of function in the plasticity of the brain

stroke victimes can recover lost abilities over time.

this suggests that localisation of function is not set and determined

what is hemispheric lateralisation?

the idea that the brain’s two halves are functionally different and that each hemisphere has functional specialisations.

what is each side of the brain responsible for?

left - language

right - visual motor tasks

how are the two hemispheres connected?

the corpus callosum are nerve fibres which facilitate interhemispheric communication

what were the dynamics of the hemispheric lateralisation study?

Sperry and Gazzaniga investigated patients that had undergone a commissurotomy (they had lost interhemispheric communication)

they conducted 3 different tests:

1. describe what is seen

2. tactile test (sensory)

3. drawing task

which hemisphere of the brain processes the left visual field?

right side (and vice versa)

what was found in the “describe what you see” task of the hemispheric lateralisation experiment?

when the picture was processed by the right hemisphere, patients were unable to describe the picture.

this demonstrated the superiority of the left hemisphere in terms of language

what was found in the tactile test of the hemispheric lateralisation experiment?

when an object was placed in their left hand (processed right hemisphere), they were unable to describe what they felt.

however they could identify it by selecting a similar object from a series of alternate objects

what was found in the drawing task of the hemispheric lateralisation experiment?

their left hand (controlled by the right hemisphere) would consistently draw better pictures (even though the participants were all right-handed)

evaluation of sperry and gazzaniga’s hemispheric lateralisation experiment.

• highly controlled + scientific

  • causation could be established between stimuli and responses

• small sample size

  • low population validity makes the findings less generalisable

what is brain plasticity?

the brain’s ability to change and adapt because of experience

what is functional recovery?

the transfer of functions from a damaged area → undamaged area

study for brain plasticity

Maguire et al. used MRI scans to analyse the sizes of the hippocampus in London taxi drivers and a control group.

Results:

1. increased grey matter was found in the posterior hippocampus of the taxi drivers

2. A positive correlation was found netween time spent as a taxi driver and volume of the posterior hippocampus

problem with Maguire’s taxi driver study

It only recorded snapshot data, meaning that it only recorded data of that specific time:

• Doesn’t show us the hippocampi grew over time

• Maybe people with bigger hippocampi become taxi drivers - not the other way around

what is neuronal pruning

the removal of redundant or otherwise unnecessary synaptic connections. it occurs between childhood and adulthood.

what are the mechanisms for recovery?

1. axonal sprouting

2. recruitment of homologous areas

3. neuronal unmasking

what is axonal sprouting?

the growth of new nerves which connect to undamaged nerves to form new pathways

what is recruitment of homologous areas?

when an area on the opposite hemisphere compensates if an area is damaged on one side

what is neuronal unmasking?

this is when secondary neural pathways are activated to enable functioning to continue.

what are the three possible views on how stem cell implantation into the brain can repair it?

1. they directly replace dead/dying cells

2. they secrete growth factors in order to ‘rescue’ the injured cells

3. an uninjured brain site is linked to the damaged region via a neural network

study on stem cells

Taijiri et al. provided stem cells to rats after brain trauma and found development of new neurons in the area of injury

study on neuron activity (plasticity)

Davidson et al. compared the neuronal activity of Tibetan monks with controls as they meditated

Bigger gamma waves were found in monks

study on recruitment of homologous areas

Danelli et al. examined a patient who had his left hemisphere removed at the age of 2. By the age of 17, his language performance was practically the same as the control group (after an intense rehabilitation programme)

evalutation of Danielli’s study on recruitment of homologous areas

Strengths:

• Application - intense rehabilitation programmes help → get used

• Brain scans v. objective

Weaknesses:

• Can't be generalised - esp. to old people (plasticity declines with age)

• Correlational data, not causational (how do we know the rehab programme really led to the recovery?)

4 ways to evaluate the ways of studying the brain

• Spatial resolution (smallest detectable feature)

• Temporal resolution (speed of the scanner’s detectors to detect change)

• Invasive vs. non invasive (insertion)

• Causation (between activity and function)

how does an fMRI scan work

They detect changes in blood oxygenation that occurs due to activity in specific parts of the brain that are active during certain processes that are completing physical demands (therefore demonstrates localisation).

strengths of fMRI scans

• safe - no radiation like PET scans

• high spatial resolution (detail) compared to EEGs + ERPs

• non-invasive

weaknesses of fMRI scans

• expensive

• poor temporal resolution compared to EEGs + ERPs

• only measures blood flow, not neuronal activity, making it difficult to tell which kind of activity is being measured. Therefore causation is problematic.

how does an EEG work

measures electrical activity via electrodes attached to the scalp.

provides a general state of the brain’s activity to indicate neurological issues.

strengths of EEGs

• useful in clinical diagnosis

• high temporal resolution compared to fMRI

• non-invasive

weaknesses of EEGs

can’t detect activity in deep region of the brain. Only superficial regions → poor spatial resolution (compared to fMRI) → problematic causation

how do ERPs work

measures electrical activity in brain with electrodes on scalp like EEGs, but with these, a stimulus is presented many times and an average response is graphed (‘averaging’).

strengths of ERPs

• more specific than EEGs

• higher temporal resolution, compared to fMRI

• non-invasive

• cheaper than fMRI scans

weaknesses of ERPs

• poor spatial resolution compared to fMRI as only superficial regions

• some stimuli are unable to be presented multiple times

  • e.g. startling sounds like a scream or loud bang. These will lose their psychological impact over time due to habituation

• time consuming for both researchers and participants

how do post mortems work

areas of damage in a person’s brain can be studied after their death and related to differences in their behaviour prior to their death

strengths of post mortems

• patient is dead, so they won't have discomfort

• fundamental in understanding the brain and localisation of function

weaknesses of post mortems

• difficult to acquire informed consent

  • acquiring retrospective consent is difficult as family members may not reflect the participants true wishes

  • post-mortems may be conducted on individuals with impaired cognitive capacity - they may not have understood when they agreed to do the procedure

• brain could have been affected during death, affecting results

length of the circadian rhythm and what resets it

The circadian rhythm lasts 24 hours and is reset by light.

how does the circadian rhythm work

1. Light is detected by the eye, which sends messages (related to brightness) to the suprachiasmatic nuclei (SCN)

2. The SCN then uses this info. to coordinate activity of the entire circadian rhythm

3. Sleeping and wakefulness are determined by homeostasis

what is an endogenous pacemaker

our body’s internal biological clocks that regulate our rhythms (e.g. SCN)