| the brain | the main coordinating centre for neural activity
it receives info from sense organs, interprets it then transmitts info to effectors |
| regions of the brain | frontal lobe
parietal lobe
temporal lobe
occipital lobe
cerebellum
hypothalamus
hippocampus
medulla oblongata
white matter
grey matter
cortex |
| frontal lobe | found at the front of the brain
concerned with decision making, reasoning, planning and consciousness of emotions
also involved in forming associations and ideas
involves primary motor cortex which stores info about how to carry out different movements |
| parietal lobe | found at the top of the brain
concerned with orientation, movement, sensation, calculation and some types of recognition and memory |
| temporal lobe | found at the bottom of the brain
concerned with processing auditory info like hearing, sound recognition and speech |
| occipital lobe | found at the back of the brain
processes info from the eyes like vision, colour, shape and perception |
| cerebellum | responsible for balance
coordinates movement
recieves info from the primary motor cortex
constantly checks is the motor programme being used is the right one
located near the brain stem |
| hypothalamus | controls temp, sleep, hunger and thirst
monitors and controls via hormones
connected to the pituitary gland
located between the thalamus and pituitary gland |
| hippocampus | involved in long term memory
located deep in the temporal lobe
also involved in learning and emotional responses |
| medulla oblongata | control of subconscious heart rate, breathing and blood pressure
located in the lowest part of the brain stem |
| white matter | corpus callosum
composed mainly of axons
white myelin sheaths give it its characteristic appearance
connects the hippocampus, hypothalamus, and other brain structures to the cortex
also connects the two hemispheres of the cortex |
| grey matter | composed of unmyelinated axons and neuronal cell bodies |
| cortex | surface of the brain
made up of grey matter
has left and right hemispheres
made up of nerve cell bodies, dendrites and synapses |
| how do doctors detect problems with the brain? | PET
CT
MRI
fMRI |
| PET | positron emission tomography
used to produce detailed images so the brain's structure and function can be evaluated
2D image but can be built up into 3D
drawbacks: exposure to radiation, expensive
benefits: no risk of X-rays |
| how do PET help diagnose brain disorders | uses isotopes C11,N13 and O15 which are incorported in molecules like glucose or water
they are radiotracers
patient ingected with radiotracers which decay then emit positrons
when the brain is active more O2 and glucose is needed
so more blood flows in that region of the brain
increases in blood flow are detected by PET as radiotracers are present in that area |
| CT | computed tomography
uses thousands of narrow beam x-rays rotated around the patient
observe structures instead of functions of the brain
drawbacks: poor resolution, exposure to x-rays may cause cancer |
| MRI | magnetic resonance imaging
uses magnetic field and radio waves to detect soft tissues
can diagnose tumors, strokes, brain injuries and infections to the brain and spine
excellent resolution 3D
benefits: no risk of x-rays,
drawbacks: magnetic field may affect pacemaker, takes only a snapshot in time |
| how do MRI detect problems with the brain? | high frequency waves and magnetic field cause the direction and frequency of hydrogen nuclei spin to change
this takes energy from the radio waves
radio waves are turned off and the hydrogen nuclei return to their original alignment releasing the energy they absorbed
this energy is detected then a signal is sent to the computer which analyses it to produce an image |
| fMRI | functional magnetic resonance imaging
provides imaging of the brain whilst in action
follows the uptake of oxygen in active brain areas
this is possible as deoxyhaemoglobin absorbs the radio wave whilst oxyhaemoglobin does not
benefits: no x-rays
drawbacks: expensive, patient must be conscious |
| how does fMRI work? | when a part of the brain is used that means there is more blood flow
therefore more blood flow means more oxygen so more oxyhaemoglabin
this means there is less absorption of the radio waves
the less absorption of radio waves means that part of the brain is really active and this will show up on the screen |
| define ethics | refer to the rules provided by an external source |
| define morals | refer to an individuals own principles regarding right and wrong |
| what are the four ethical frameworks? | rights and duties
maximising the amount of good in the world
making decisions for yourself
leading a virtuous life |
| what are the conditions on using animals in research? | consider the animal's welfare for normal behaviour, health, food and water
only use as few animals as possible
use invertebrates as much as possible
the animal cannot be endangered like the great ape or orangutan |
| abolitionist vs utilitarianism | abolitionist argue that animals can't give consent so it is never ok to use them
utilitarians argue that if it is for the greater good then it is fine to use them as long as they follow the conditions for using animals in research |
| habituation | a type of learning
gives animals the ability to ignore unimportant repetitive stimuli so that the limited sensory, attention and memory resources can be concentrated on more rewarding or threatening stimuli
does not alter the sensory system |
| how do animals become habituated to stimuli? | stimulus is applied
impulse passes along the sensory neurone which synapses with the motor neurone
the motor neurone passes the impulse to the effector causing a muscle to contract or gland to secrete
with repeated stimulus the Ca2+ channels of the sensory neurone become less responsive to changes in voltage
so less neurotransmitters are released so less Na+ enter the motor neurone
no action potential generated in motor neurone and no impulse is passed on to the effectors
the animal has become habituated to the stimulus |
| investigate habituation to a stimulus in snails | dampen a cotton bud with water
firmly touch the snail between the eye stalks with the dampened cotton bud and immediately start the stopwatch
measure the length of time it takes for the snails eye stalks to reemerge
repeat this until the snails eye stalks stop retracting
record the results and carry out repeats to get a mean |
| what is dopamine? | neurotransmitter secreted by hormones
promotes reward motivated behaviour
when dopamine levels are too low it can cause Parkinson's disease
when dopamine levels are too high it can cause schizophrenia |
| symptoms of Parkinson's disease | stiffness of muscles
tremor of muscles
slow movement
poor balance
walking problems |
| treatments of Parkinson's disease | selegiline - MAO inhibitor - stops MAO enzyme breaking down dopamine
L-dopa - dopamine precursor that can enter the brain via the bloodstream
dopamine agonist - mimic dopamine by binding to its receptors, reduces risk of side effects of high dopamine levels
DBS - deep brain stimulation, surgery which treats the symptoms reduces risk of side effects of high dopamine levels |
| what is serotonin? | neurotransmitter involved in determining someone's mood |
| symptoms of depression | feelings of sadness, anxiety and hopelessness
can go on for weeks and months
loss of interest in probable activities, reduced energy levels, insomnia, thoughts of death |
| treatments for depression | MAOI's - they break down serotonin so they are rarely used due to adverse side effects
SSRI - selective serotonin reuptake inhibitors, increases serotonin level blocks the reuptake of serotonin from the synaptic cleft |
| why can't dopamine be given exogenously? | dopamine can't enter the brain via the bloodstream |
