Methods Slides Flashcards
the brain works through __
neuronal signaling
neurons that ___
fire together wire together
associations can be ____
spatial or temporal
all neuronal change is ultimately caused by the ___
environment (including the body
what is a mental representation?
a pattern of neural activation that is affected by weighting
weighting is based on ___
prior experience and context (aka present experience)
weighting can be changed by
context
what are the 3 levels of representations
visual, sound, category
vascular disorders (cause of neurological dysfunction)
brain needs a continuous supply of oxygen - vascular disorder disrupts this
angiography (cause of neurological dysfunction)
visualize distribution of blood
4 types of cerebral vascular accidents (strokes)
occlusion
ischemia
cerebral hemorrhage
aneurism
occlusion
atherosclerosis embolism
ischemia
can be caused by blockage or drop in blood pressure
cerebral hemorrhage
bleeding in brain due to burst blood vessels - sudden rise in blood pressure
aneurism
weak spot or distension in a blood vessel - can expand or burst
tumors
a mass of tissue that grows abnormally and has no function
difference between benign and malignant tumor
benign tumors do not grow back
malignant tumors likely to return and distribute
most tumors form from…
glia - but other grey matter tumors also form
closed traumatic brain injury
mechanical forces damage the brain
5 causes of neurological dysfunction
- cerebral vascular accident
- tumors
- degenerative or infection diseases
- traumatic brain injury (TBI)
- Epilepsy
epilepsy
excessive and abnormally patterned activity in the brain
-can range in severity and frequency
coup TBI
injury in which the brain damage occurs on the same side as the site of impact
contre coup TBI
injury in which the brain damage occurs on the opposite side as the site of impact
single dissociation
one patient group shows impairment on a task relative to controls
double dissociation
two patient groups show impairments on two different tasks
problems with double dissociation
cannot claim due to general effects of brain damage because both groups have brain damage
-cannot claim difficulty, concentration, attention
ways to go around problems with double dissociation
- choose patients with same damage and study behaviour
- choose patients with same behavioural deficit
downsides of using lesioned patients
variability among patients
lesion can affect more than one structure
input/output from site also damaged
brain = massively interconnected. what does a small lesion tell us?
significant plasticity
methods to disrupt neural function (2)
- use of drugs
- brain stimulation
benefit of using pharmacology
can gain insights into NT actions by administering drugs that are known to affect function
4 types of brain stimulation
- electroconvulsive shock therapy (ECT)
- transcranial magnetic stimulation (TMS)
- Deep brain stimulation (DBS)
- Transcranial direct current stimulation (tDCS)
ECT
electroconvulsive shock therapy
-electrical currents are passed through the brain causing brief seizures
main use of ECT
treatment for depression - though researchers are not quite sure how it works
TMS
transcranial magnetic stimulation
- use rapidly changing magnetic field to induce electrical impulses
- single pulse or repetitive
- current flows in opposite directions and converges on the center where the current summates
uses of TMS
virtual lesions
therapy
single pulse
“virtual lesions”
- short monophasic electrical pulse to the brain that lasts .2 seconds
- effective area of stimulation is not focual
inference with function
- prevent activity by silencing neurons
2. add noise to ongoing activity
rTMS
- repetitive pulses
- effects can last 30-60 minutes
- can also increase motor reaction times
therapeutic uses of rTMS
treatment for major depression
- more effective than drugs, less than ECT
- not very common
tDCS
- transcranial direct current stimulation
- changes cortical excitability by constant, weak electrical current
- can excite or inhibit depending on polarity of current
- changes can last for hours
- portable
when tDCS is applied to stroke patients…
they have an increased use of limbs and increased activity in damaged cortex
DBS
deep brain stimulation
-stimulator is implanted in regions known to affect behaviours
treatment uses of DBS
- parkinsons (tremors, motor disabilities)
- testing for treatment of depression and schizophrenia
structural imaging techniques
x-ray
MRI
CT (computerized tomography)
how does xray work
pass xrays through skull to be absorbed by diff tissues to dif degrees
CT
computerized tomography
produces 3d image of brain
similar process to xray but more specific
EEG
electroencphalography
- way to measure neuronal firing patterns
- continuous recording of overall brain activity
MRI
non invasive neuroimaging technique
uses radio waves in a magnetic field
completely safe
good spatial resolution, no temporal resolution
RF pulse
used in MRI to mess with the protons which creates a signal that can be measured
what is measured in the MRI?
the different relaxation rates of protons in different tissues
diffusion tensor imaging
measures axon tracts - same set up as MRI
uses diffusion characteristics of water
ERP
event-related potentials -measures brain activity during a particular task average signal during stimulus event poor spatial localization good temporal resolution
MEG
Magnetoencephalography
- uses magnetic signals instead of electrical signals
- better spatial resolution than EEG
- can only localize signals parallel to skull surface
electrocortigram
similar to EEG but electrodes are placed directly on brain
Positron Emission Tomography
PET
measures local variation in cerebral blood flow
-measures radioactive tracer
BOLD
blood oxygenation level dependent signal
-what is measured in fMRI
limitations of PET and fMRI
poor temporal resolution
correlations not causations
neural systems not areas
