Biological Psychology Flashcards
Lecture 1 and 2 TMS
Where is the strongest effect for tms
In the centre with a radius of 3-4mm
Lecture 1 and 2 TMS
basis of what occurs during TMS
It puts artificial currents in the brain which depolarises neurons in a small area of cortex. As neurons fire randomly this creates neural noise
- this process was created by fritsch and hitzig
lecture 1 and 2 TMS
What is rTMS
Repeated TMS with fast sequences of pulses (100-200)
Lecture 1 and 2 TMS
4 approaches of TMS
- Injection of neural noise = single pulses to show us causality which is really good and unmasking is used between 60-140ms which informs us about time course processing
- Virtual lesion approach = using rTMS which lowers the strength of stimulation but allows more pulses to enter the cortex
- Probing excitability = single pulses looking at the activation of the motor cortex which can be measured by recording MEPS and will display mental rotation
- Paired pulse which involves 2 brief pulses. This is often used for patients with schizophrenia
Lecture 3 and 4- EEG
What’s the basis of an EEG
Electrodes on scalp will detect electrical activity/neural as they receive electrical signals
.64 cap holes in the hat which is non invasive
.spatial resolution is not good
.temporal resolution is good
Lecture 3+4 EEG
when did Berger say we would see an alpha rhythm?
Occurs when relaxed at 8-13Hz
Lecture 3+4 EEG
EEG signals and the clean up
Signals are tiny at 10uv-100uv so they must be amplified to be observed but they also must be cleaned to eliminate sweating, blinking etc.
.the better signals are found in the gyri
Lecture 3+4
EEG
What’s an ERP
The measured brain response that is the direct result of a specific sensory neuron or event and reflect brain activity that is related to a kind of stimulus
.the good thing about ERPs is that there is no noise and they are good AT looking at cognitive processes
Lecture 3+4
EEG
What is an ERN?
A negative deflection of up to 10uv
.gering found that the greater the ERN the lower the response force and the higher the probability to get it right on the next trial by the slower the response
.only observed on EEGs after errors are committed during choice tasks
Lecture 5 - data analysis
how do we find the variance of our sample?
SS(sum of squares)/degrees of freedom
lecture 5 - data
how do we find the standard deviation
square root of our variance
lecture 5 - data
what is the standard error?
the standard deviation of the mean of the distribution of individuals
lecture 5 - data
what does a t test stat represent?
how much greater or less the sample mean is than the hypothetical mean relative to the standard error
lecture 5 - data
when can we reject the null hypothesis?
when the t -statistic is larger than the standard error
.if the t stat is less than the Se we cannot reject the null
lecture 5 - data
what is a type 1 error?
saying the null is false when it is actually true
lecture 5 - data
what is a significance level
this indicates how probable it is that you might reject the null and if you do how likely it is that you have made a mistake (thus making a type 1 error)
lecture 5 - data
as the critical value goes up what does down?
the degree of freedom
lecture 5 - data
effect size - what constitutes as a small or big effect size?
- 01 = small
- 13 = middle
- 25 = large
lecture 5 - data
when do you do a one tailed test?
.if the alternative hypothesis states that the mean will be either greater or less
.you do a two tailed if you think the mean will just make a difference (no direction just one assumption)
lecture 7 - fMRI
what is a BOLD fMRI
looks at the blood flow when the subject performs a task and then is compared when the subject does nothing
.It looks at the neural activity which when this increases the oxygen level increases making the magnetic field more homogenous making the fMRI slower but stronger
lecture 7 - fMRI
what happens when we only want to see a slice of the brain?
we use an RF pulse (radiofrequency) - which will excite only a slice of the brain where the resonance frequency of the protons match the frequency of that RF pulse allowing a 3D image to be created
lecture 7 - fMRI
how do we locate where the BOLD is originating?
.where we excite using the radio frequency pulse we know is z-coordinate
.we then phase encode by measuring the RF pulse to find the x coordinate
lecture 7 - fMRI
what does the frequency RF pulse show us when we are phase encoding?
the y-coordinate which occurs during readout
lecture 7
fMRI
does fMRI involve radiation?
no - its non invasive
however, uses a very strong magnet field
lecture 7
fMRI
what is the radioactive isotope that is administered to the patient during an fMRI
an oxygen-15
lecture 7
fMRI
what is BOLD fMRI
blood oxygen level dependent fMRI that looks at blood oxygen levels that get increased due to an increase of blood in the brain and neural activity
lecture 7
fMRI - how does it work?
the nuceli of the hydrogen atoms act as bar magnets. Put into a magnetic field they are wanting to align to that magnet however sometimes they cannot align perfectly so they precess around the magnetic field.
This precessing changes the magnetic axes further changing the frequency
.the magnet attracts a radio frequency pulse BUT only if the resonance frequency of that proton found matches the frequency of the pulse of that proton
.this proton will only absorb the energy when it has the right match of resonance frequency
.the computer picks up the radio frequency pulses when all is turned off creating an image of the brain
lecture 7
fMRI - how can we measure how homogenous the magnetic field is?
by measuring the rate at which the strength of the RF signals emitted by the tissue decreases
lecture 7
fMRI
Higher the BOLD the more homogenous the magnetic field…
…the slower the radio frequency emitted from the brain
lecture 7
fMRI
stronger the signal in an fMRI…
…the greater the neural activity
lecture 8
fMRI
common criticisms…
- Multiple comparison problem - because you have to perform so many t-tests (50,000) and the more t tests you perform the greater the possibility of a false positive or a type 1 error
- THIS CAN BE AVOIDED WITH THE BONFERRONI CORRECTION WHERE YOU CAN PERFORM EACH T TEST AT THE 0.01/N LEVEL
…another way to avoid this is to find a region of interest (one big voxel) and you do a t-test on this ROI comparing its activity in the 2 conditions and because you are not doing several t-tests you are less likely to miss a significant result
…but for ROI to work you must only use different scanning sessions for the identification if you dont this is all called the non-independent sampling confound (Baker et al. looked into this finding that those you do not use one scanning session end up making over half the amount of errors)
…final criticism is that if there is a null result it is hard to conclude much which is called an over interpretation of null results
lecture 7
fmri - how do we find the y-axis during phase encoding?
at readout - by listening only to one frequency we can determine the y-coordinate which is known as frequency encoding
lecture 7
fMRI - spatial vs temporal resolution
poor temporal
good spatial - we scan at 3x3x3mm cubed
lecture 8
fMRI
what did Kanwisher find on his expoloration with fMRI?
that there is a specific part of our brain that processes faces
- to do this they found that an area of the fusiform gyrus responded more strongly to faces than objects in several conditions
lecture 8
fMRI
common criticisms…
- Multiple comparison problem - because you have to perform so many t-tests (50,000) and the more t tests you perform the greater the possibility of a false positive or a type 1 error
- THIS CAN BE AVOIDED WITH THE BONFERRONI CORRECTION WHERE YOU CAN PERFORM EACH T TEST AT THE 0.01/N LEVEL
…another way to avoid this is to find a region of interest (one big voxel) and you do a t-test on this ROI comparing its activity in the 2 conditions and because you are not doing several t-tests you are less likely to miss a significant result
…but for ROI to work you must only use different scanning sessions for the identification if you dont this is all called the non-independent sampling confound (Baker et al. looked into this finding that those you do not use one scanning session end up making over half the amount of errors)
…final criticism is that if there is a null result it is hard to conclude much which is called an over interpretation of null results
lecture 9 - anatomy and makeup of our memory
long term potentiation/depression
LTP - lots of excitability of a neuron to a synaptic input causes repeated high frequency activity of that input (this is known as Hebbs rule) learning occurs through this
LTP occurs in the hippocampus, PC, motor cortex, VC, thalamus and amygdala
LTD = low frequency stimulation at synapse decreases synapse strength
lecture 9 - anatomy and make up of memory
2nd region - Frontal lobes
involved with motor programming and performance
…lesions to frontal lobes impact memory such that the individual will not remember contextual details and chronological order of events which leads to an error called confabulation
lecture 9 - anatomy and make up of our memory
Habituation and sensitisation
H - lots of stimulation reduces the strength of synapse response
S - single noxious stimulus makes synaptic response to repeat presentation of noxious stimulus
lecture 9 - anatomoy and makeup of our memory
synaptic plasticity
learning involves this and the synapses change to alter the effect on post synaptic neuron
lecture 9 - anatomy and makeup of our memory
long term potentiation/depression
LTP - lots of excitability of a neuron to a synaptic input causes repeated high frequency activity of that input (this is known as Hebbs rule)
LTP occurs in the hippocampus, PC, motor cortex, VC, thalamus and amygdala
LTD = low frequency stimulation at synapse decreases synapse strength
lecture 9 - anatomy and make up of our memory
Hebbs rule
causes synaptic changes as new receptors are inverted into post synaptic membrane
lecture 9 - anatomy and make up of our memory
Habituation and sensitisation
H - lots of stimulation reduces the strength of synapse response
S - single noxious stimulus makes synaptic response to repeat presentation of noxious stimulus
lecture 10
cognitive theories of memory
1st memory mode (Atkinson-Shiffrin model)
2nd levels of processing
3rd Tulvings Model of memory
4th: parallel distributed processing
sensory memory to working memory to long term memory
2nd memory model - information is retained according to the level of processing it has undergone
3rd - Long term memory branches to either declarative memory (semantic or episodic) or procedural memory
4th - memory is activation of connections in different areas simultaneously and learning depends on the strength of these connections
lecture 10
cognitive theories of memory
what is semantic and episodic memory?
S = word meanings. This type of memory is not parallel with episodic memory but squire and zola argued that they might be as damage to hippocampal systems results in equal impariment to both S and E E = your last birthday/where you went for summer last year and this works by autonoetic (being able to put yourself in the past future and present) awareness and does depend on your semantic memory
lecture 10
cognitive theories of memory
Tulvings SPI hypothesis
Tulving stated that
- encoding into episodic memory relies on the semantic system
- and encoding into semantic memory relies on the semantic system
- and episodic memory is an extension of the semantic memory
Vargha-Khadem et al. collected findings that supported Tulvings hypothesis as they saw episodic memory relies on semantic memory but not the other way round by looking at patients with abnormally small bilateral hippocampi but intact extra-hippocampal temporal lobes
