brain learning and motivation: cognitive neuroscience Flashcards
**cortex
wheremost o the higher function takes place
size of brains
male brains are usually around 200g heavier than female brains
humans don’t have the heaviest brains i the world
the longitudinal issuer
divides the brain into its right and left hemispheres
though the two sides are still connected
**Corpus Callosum
the connection tissue between the right and left hemispheres of brain
Pia Mater layer and the Arachnoid layer
the brain is protected by many layers of tissue these are two of them between which there is cerebral fluid
stroe
occurs when blood supply to the brain is cut off/ not getting to the right place
Ventricles in brain
primarily contain cerebral fluid, produced by the brain
the Broca area and Wernicke areas
respectively responsible for language production and language comprehension
lesions in these areas can lead to aphasia as they are on left hemisphere
The Penfield & Rasmusen experiment, in 1950
involved stimulating parts of a patient brain to determine which areas were responsible for what function
the size of corresponding brain areas
depends on the importance of the body part they represent e.g. the hand has a large area because it is very sensitive
can carry out a number of different functions
and is packed with receptors
techniques used in cognitive neuroscience: single cell recording
a technique used in research to observe changes in voltage or current in a neuron.
n this technique an animal, usually anesthetized, has a microelectrode inserted into its skull and into a neuron in the area of the brain that is of interest
the electrode measures the change in charge as the neuron reaches its action potential ( the voltage at which the neuron is active)
… in response to cerain stimuli
single cell recording : found
different cells react to different stimuli e.g. a light moving in a line would stimulate different cells to one situated in a different orientation
visual cortex and central vision (fovea
in monkeys it was found during a single cell recording that 40% of cells in the visual cortex were stimulated by the central vision because this is the most detailed point of vision
primary visual cortex
receives all visual input from the retina
techniques used in cognitive neuroscience: lesion studies
lesions on the brain caused by stroke i.e. loss of blood supply to certain areas, brain damage and trauma
some patients could have one lesion , some could have several and some could have one large lesion… therefore its impotent that tests are carried out to understand which lesions cause which conditions i.e.. which part of the brain being damaged is responsible
lesion studies: Aphasia
caused by lesion of the left hemisphere of the brain
effects of aphasia
sufferers may have difficulty speaking, reading, writing, recognizing the names of objects, or understanding what other people have said
hemispatial neglect
caused by a lesion on the right hemisphere of the brain
hemispatial neglect effects
causes sufferers to ignore the left side e.g. eat dinner only off the right side of the plate
tests for hemispatial neglect
patients would be given a sheet with something on it and be asked to copy it withou moving the sheet,
if a sufferer they would only copy the right hand side
another test is to give them a sheet with big stars and little stars and ask ten to cross out all small stars… sufferers would not cross out small stars on left
techniques used in cognitive neuroscience: transcranial magnetic stimulation (TMS)
uses n electrically charged coil which is placed against the scap.
this creates a magnetic fied that interferes with brainwaves in the desired area that the coil is positioned at
use to create artificial lesions this helps in determining which lesions cause what behaviour in specific areas in the brain
TMS advantages
can be done on healthy undamaged brains and subjects
wider range of subjects
rules out interference of other lesions
TMS disadvantages
patients participating often move around when having the hlmrt put on discharging the magnetic field
depending on which part of the brain you want to test you need to know exactly where to place the coil this can be difficult in small areas
coil position must be guided and monitored
since the magnetic field is weak it cannot reach deeper areas in the brain
brain imaging techniques
can be broken into 2 categories:
Structural techniques
functional techniques
structure brain imaging techniques
used to to observe the oxmposition and interrelated parts of the brain
functional techniques
used to observe what a part of the brain does and how it works
structural imaging techniquesL examples
photo
CT scan
MRI scan
staining
functional imaging techniques- electrical activity (electromagnetic): examples
single cell recording
EEG
MEG
structural scanner: computer tomography (CT)
X-ray scanner rotates, taking images at different angles and planes (depths)
• Different tissues absorb different amounts of radia
structural scanner: magnetic resonance imaging (MRI)
Magnet: Very strong magnetic field (3T = 60000x earth magnetic field) Gradient Coils: Enables spatial encoding Radio Frequency Coil: Receives and transmits radio frequency waves (absorbed and released by hydrogen atoms) 
CT: advantages
short scan time
cheaper than MRI
good for bone images
CT disadvantages
not suitable for pregnant women or children
could cause irradiation
uses X-rays
less detailed imaged than MRI
MRI advantages
detailed images of soft tissues
MRI disadvantages
expensive
nor ideal for large people/cjlostrophobic people
no ferromagnetic objects can be worm inside people with coloured tattoos etc
long scan time
functional scanner: Functional Magnet Resonance Imaging (fMRI)
observes blood flow in the brain… since active brain tissue uses more blood and blood contains oxygen that has magnetic properties this is how its observed
funtional scanner: positron emisson tomography; PET
Radioactive water injected into subject
Radioactive positrons follow blood flow to active sites Positrons set off detectors that measure their position
fmri advantages
magnetic field so no likelihood of radiation
good spatial resolution
fmri disadvantages
expensive
no feromagnetic objects
not suitable for very large or chlostrophovic people
poor temporal resolution
pet advantages
can image biological processes
good spatial resolution
pet disadvantages
poor temporal resolution
not suitable for pregnant women or children
possibility of iradiation since it uses X-rays
very expensive
involves a radioactive which people can be uncomfortable about
techniques used in cognitive neuroscience
Single Cell Recording
Lesion studies
Magnetic Stimulation (TMS)
Brain Imaging Technique
making neutrons visible
can be done through golgi stain and neisil stain
Electroencephalogram (EEG(
electrodes attatched to scalp surface measures electrical activity generated by the brain
many electrodes
fixed in spacific places
each line of wave represents each electrode
EEG waves
beta 13-30 hz very awake
alpha 8-13 hz relaxed
theta 4-8 hz sleepy
delta 0.5-4hz deep sleep
event related potential (ERP)
EEG during a task to measure brain activity during specific task
reference point to note when stimulus was presented to calculate average of meaningful data
peaks in waves will appear for when stimulus was presented
n and p refer to negativie and positive changes in voltage
Magnetoencephalogram (MEG)
measures the magnetic field surrounding brain
superconducting quantum interferance devices inside machine at specific points all over the head but not attached likee EEg
very sensitive to magnetic field
done in isolated room to avoid interference of other magnetic fields
brain magnetic field
smaller than earths magnetic field
MEG output
curve of mean output from device
shows changes in magnetic field
EEG advantages
measures electric current
good temporal resolution
cheap
EEG disadvantages
affected by conductivity of scalp
poor spatial resolution
MEG advantages
unaffected by scalp
measures magnetic field
good temporal resolution
MEG disadvantages
needs shielding from other magnetic fields
spatial resolution depends on depth
expensive
brain imaging techniques: good spatial resolution
PET
fmri
sometimes MEG dependant on depth
brain imaging techniques: poor spatial resolution
EEG
ERP
sometimes MEG dependant on depth
brain imaging techniques: good temporal resolution
MEG
EEG
ERP
brain imaging techniques: poor temporal resolution
pet
fmri
